SSD and computer casing.

Bob_S wrote:
"Paul" wrote in message news

Bob_S wrote:
"Paul" wrote in message news
Peter Jason wrote:
On Sat, 14 Apr 2018 22:25:50 -0400, Paul
wrote:

Peter Jason wrote:
My computer case is of Aluminium and earthed to a domestic copper
water pipe. , the casing of the Samsungs SSDs seem to be anodized
aluminium. Since my computer case is old it has no provision for
2.5"
SSDs I have them resting on an aluminium surface. Is this a
problem?
I assume the SSDs have internal insulation.
I just measured a couple SSDs here, and son of a bitch,
there's a hard connection between SSD casing and logic ground!

That's not supposed to be good for ESD handling.

I was expecting to find a 1 megohm connection between
aluminum SSD casing and the logic ground on the SSD.

But it's a hard short.

*******

The chassis of your computer case, runs at logic ground
potential.

The casing of your SSD, runs at logic ground potential.

This means you can safely rest the SSD on the bottom of
the computer case, without any "thru" current flowing.

Just don't touch a 3.3V, 5V, or 12V pin from some
Molex connector, to the chassis of the SSD. Since
it's a hard ground, we can't be carelessly resting
a Molex power pin in contact (somehow) with the chassis.

While the pins on Molex are flush or
slightly recessed, there might be some conceivable
way for something to touch. And my finding a
hard ground on the SSD chassis, is not a good
thing.

I'll be extra careful in future, to keep Molex
away from it.

I was really expecting to find a 1Megohm (high resistance)
drain between shiny aluminum SSD casing and the logic
ground next to the data pins of the SSD.

GND GND GND === logic ground pins are longer
tx+ tx- rx+ rx- on the SSD connector. The
data
pins on the 7 pin data are
recessed. Check with the
ohmmeter,
between GND and chassis,
and you'll
see the hard short I
measured.

Summary:

1) Safe to rest SSD on bottom of computer case, no matter
what the casing is made of.

2) Don't touch any "hot" Molex pins, to the SSD housing.
Just like you would not touch any "hot" Molex pins,
to the computer case metal posts. The motherboard has a hard
short to the chassis, through the standoffs. Most everything
in the computer, has a hard ground. The only poorly designed
feature, is "plastic fascia" on the front of the computer,
around front USB ports, which is a poor way to handle ESD issues.

3) Don't scuff across the carpet and pick up your
SSD by the aluminum casing. Keep unused SSDs in an ESD bag,
scuff across the carpet if you must, pick up the
SSD by the ESD bag, touch the ESD bag plastic on
the inside of the bag, to bring yourself and the bag contents
to the same potential. With your other hand, touch
the computer chassis. Now, everything is "drained" to
the same electrostatic potential, you can remove the
SSD from the ESD bag, and connect it to SATA power
and SATA data.

By using the series resistance of the ESD bag, to limit
ESD current flow, you're *safely* bringing the SSD up
to the same electrostatic potential as the thing you
wish to connect it to.

Note: I just changed my handling procedure! as a result
of this ohmmeter measurement. I'd assumed SSD chassis
were drain connected, not "hard" connected. Now I
will have to start using ESD bags for them, just as
I do for hard drives.

Paul


Thanks Paul. I have put my SSDs in plastic sleeves, and rested this
combination on cardboard. I thought this might be the cause of my
computer restarts. Also I have disabled all "fast startups" via the
registry.

I wouldn't entirely insulate the thing. Some SSDs have
high peak power usage (SandForce compression), and they
get a little warm.

Put a cardboard underneath if you like. Leave
at least one metal surface for cooling.

In this review, you can see (and it's mentioned in the text),
that thermal pads were used on all the NAND chips. That means
both metal surfaces are used for their slight cooling advantage.

http://www.thessdreview.com/our-revi...-review-512gb/


Paul

Paul,

Have no idea why you would expect the SSD to be isolated from case
ground. Everything in the computer and the case itself is tied to the
grid ground. Mount a motherboard and the mounting screws screw into
the case as well as the screw heads tighten down on ground pads on
the motherboard. SSD's are also grounded when placed in a mounting
tray to case ground.

As for the longer pins on power and data connectors, the pins that
are designated as ground pins are longer to insure a ground
connection is made before any data pins mate to prevent static
discharges. This pin design also accommodates "hot swap" capable
devices such as hard drives and SSD's.

While it's always good practice to use measures to prevent ESD when
mounting a device such as a SSD, do not isolate it from the mounting
mechanisms such as placing an insulator between it and a metal case.
Depending on the SSD (some cases are plastic), the metal case is the
heat sink as shown in the link you included in your post. Please
note that the logic board is held in-place by a screw in the back
that fastens to the SSD case and tightens against a ground pad on the
SSD logic board.

There are two ground philosophies for protecting assemblies
from ESD.

Neither was followed in this case.

Paul

Paul,

Not sure I follow your logic on this. The OP said he had his case
grounded to a copper pipe. What wasn't stated is how his power supply
is grounded or if it was even plugged in. In the US, the 3rd lug on a
plug is the green (safety) ground and in a typical home wiring setup,
the white wire and green are tied to a single bus bar in the
distribution panel so as to prevent ground loops / current loops.

So while his setup using a ground from the case to a copper water pipe
could potentially create a ground loop if there were other wiring
problems, it still is ground as long as there's no interruption to earth
ground in that copper pipe and in his wiring and would dissipate any ESD
charge.

Potential for ESD would be from him picking up the SSD and then plugging
it in before he touched the case (grounding himself) and creating a arc
between his hand holding the SSD and getting the data or power
connectors close enough so the static potential went from him to the
ground pins on the cable or the case.

That’s' why the manufactures include warnings about using ground straps
and/or touching the case before working on it. What people don't
realize is that usually, they unplug the power cord from the wall or the
power supply and that’s when their case is no longer grounded. But in
the OP's situation, he had an additional ground to a water pipe. That
may or may not be a good situation depending on his house wiring and
I've never seen a power supply plug without a polarized plug. Now if
the wall socket (old house wiring) does not have a safety ground, then
his water pipe ground is a good idea.

I've worked at radar sites and on some of the largest computer
installations in the world and worked worked with power engineers that
specialize in how "all things" need to be grounded and why. It is a
complicated field of study and ESD can create havoc on computer
components when you have thousands of volts jumping between you and the
computer.

So I'm not trying to argue with you but saying "Neither was followed in
this case" didn't make sense to me. Perhaps you could expand on the
"Neither" a bit. I'm not sure if you are referring to the OP or to your
own situation. If it's your own, then I'll shut up and sit down cause I
don't know what or how you were doing your measurements.

1) There's no such thing as "ground". The earth is an insulated
ball floating in the vacuum of space. The earth is merely
a "reference point". It has no special properties as such.
"Standing on dirt is not magic." But since we are in frequent
contact with dirt though, it's in our best interest to not
touch potentials higher or lower than that potential. We could
get a shock.

2) To avoid ESD, bring all assemblies to "equipotential".
That's the trick.

If I unplug a PC from the wall, remove all cabling,
I can still *safely* install hardware in it, as long
as I follow equipotential rules. This means opening
the ESD bag but not removing the new hardware. Touch the
inside of the bag while touching the chassis. It helps
if you wear short pants and lay the metal-bodied PC flat
on your lap while working (that's if you don't own an ESD strap).

By bringing the PC, the new hardware item, and you to the
same electrostatic potential, there is no danger of ESD
damage.

And notice in that picture, there is *no* connection to
earth ground, safety ground, cold water pipes or anything.
You make an "electrostatic island" of yourself, then ensure
that all entities are "charged to the same level".

I could place my work chair on glass blocks, charge
myself to 50kV ESD level, and as long as I followed
the rules about touching the inside of the ESD bag to
bring the bag to the same potential as the other
kit, I can actually install something without damage.

The usage of ESD straps (where the ESD strap is fastened
to the case via a 10meg series resistor), is for a similar
purpose. It's not ground - it's a way to bring the
computer chassis and any other objects used in the
operation, to the same electrostatic potential. The
series resistor inside the strap, performs the same
function as the "resistive" surface inside the
ESD bag. It's a dissipative path, that limits the
ESD peak current flow level.

By placing a hard connection between the metal chassis
of the SSD and logic ground, now we have to resort
to ESD bags again, as there is no dissipative path
to logic ground. I can't really afford to scuff across
the carpet, and discharge 50kV into the SSD chassis,
because the result will now be unknown (I won't know
whether I could have damaged it or not, and it
could depend on the way the PCB and mount points are
designed). If the connection between SSD chassis
and PCB was dissipative, then I'd know there was
no possibility of a high "peak" current flow during
equalization. If the SSD chassis was plastic, I would
be using the second philosophy, which says "don't allow
static to dissipate into the item at all". Then the
advanced ground contacts take the brunt of the
equalization current flow.

And things like this aren't left to chance in the lab.
If I wanted to be sure my decision about the hard
ground on the SSD wasn't a mistake, I do this
kind of testing. We test for upset level. We
test for damage level (which is actually pretty
hard to determine, what constitutes "damage").
The bad thing about ESD, is you can "weaken" a
piece of silicon, which weeks later, decides to
completely fail. And then it's hard to trace back
exactly when you "broke it".

https://en.wikipedia.org/wiki/Human-body_model

These have changed, since the last time I tried this stuff.
We had a nasty gadget for doing up to 15kV tests on
our products. This is so much more "refined" looking.

https://transientspecialists.com/pro...contact-mode-1

There are two ways to damage things with ESD. One is
via direct discharge. The other is via "induction". When
usage of an improperly designed front USB solution blows
out the pad I/O, it's just as likely the transient
traveling down the black wire, "induces" a potential
in D+ and D-, and blows out the driver pad. When you do ESD
analysis, the danger isn't always from the direct path.

I will be switching to ESD bags from now on, for my
SSDs, and bringing myself to the same potential as the
chassis. (The same kind of gymnastics you do, when you
don't have an ESD strap handy.) It's not because I know
for a fact the SSD will fail. It's because I don't really
know, for any individual SSD, whether it has a particular
vulnerability or not. If I had a pile of these in the lab,
and an HBM-type tester, I could take a shot at finding out.

Paul

On Sun, 15 Apr 2018 22:32:36 -0400, "Bob_S" wrote:

"Paul" wrote in message news

Bob_S wrote:
"Paul" wrote in message news
Peter Jason wrote:
On Sat, 14 Apr 2018 22:25:50 -0400, Paul
wrote:

Peter Jason wrote:
My computer case is of Aluminium and earthed to a domestic copper
water pipe. , the casing of the Samsungs SSDs seem to be anodized
aluminium. Since my computer case is old it has no provision for
2.5"
SSDs I have them resting on an aluminium surface. Is this a
problem?
I assume the SSDs have internal insulation.
I just measured a couple SSDs here, and son of a bitch,
there's a hard connection between SSD casing and logic ground!

That's not supposed to be good for ESD handling.

I was expecting to find a 1 megohm connection between
aluminum SSD casing and the logic ground on the SSD.

But it's a hard short.

*******

The chassis of your computer case, runs at logic ground
potential.

The casing of your SSD, runs at logic ground potential.

This means you can safely rest the SSD on the bottom of
the computer case, without any "thru" current flowing.

Just don't touch a 3.3V, 5V, or 12V pin from some
Molex connector, to the chassis of the SSD. Since
it's a hard ground, we can't be carelessly resting
a Molex power pin in contact (somehow) with the chassis.

While the pins on Molex are flush or
slightly recessed, there might be some conceivable
way for something to touch. And my finding a
hard ground on the SSD chassis, is not a good
thing.

I'll be extra careful in future, to keep Molex
away from it.

I was really expecting to find a 1Megohm (high resistance)
drain between shiny aluminum SSD casing and the logic
ground next to the data pins of the SSD.

GND GND GND === logic ground pins are longer
tx+ tx- rx+ rx- on the SSD connector. The data
pins on the 7 pin data are
recessed. Check with the
ohmmeter,
between GND and chassis, and
you'll
see the hard short I measured.

Summary:

1) Safe to rest SSD on bottom of computer case, no matter
what the casing is made of.

2) Don't touch any "hot" Molex pins, to the SSD housing.
Just like you would not touch any "hot" Molex pins,
to the computer case metal posts. The motherboard has a hard
short to the chassis, through the standoffs. Most everything
in the computer, has a hard ground. The only poorly designed
feature, is "plastic fascia" on the front of the computer,
around front USB ports, which is a poor way to handle ESD issues.

3) Don't scuff across the carpet and pick up your
SSD by the aluminum casing. Keep unused SSDs in an ESD bag,
scuff across the carpet if you must, pick up the
SSD by the ESD bag, touch the ESD bag plastic on
the inside of the bag, to bring yourself and the bag contents
to the same potential. With your other hand, touch
the computer chassis. Now, everything is "drained" to
the same electrostatic potential, you can remove the
SSD from the ESD bag, and connect it to SATA power
and SATA data.

By using the series resistance of the ESD bag, to limit
ESD current flow, you're *safely* bringing the SSD up
to the same electrostatic potential as the thing you
wish to connect it to.

Note: I just changed my handling procedure! as a result
of this ohmmeter measurement. I'd assumed SSD chassis
were drain connected, not "hard" connected. Now I
will have to start using ESD bags for them, just as
I do for hard drives.

Paul


Thanks Paul. I have put my SSDs in plastic sleeves, and rested this
combination on cardboard. I thought this might be the cause of my
computer restarts. Also I have disabled all "fast startups" via the
registry.

I wouldn't entirely insulate the thing. Some SSDs have
high peak power usage (SandForce compression), and they
get a little warm.

Put a cardboard underneath if you like. Leave
at least one metal surface for cooling.

In this review, you can see (and it's mentioned in the text),
that thermal pads were used on all the NAND chips. That means
both metal surfaces are used for their slight cooling advantage.

http://www.thessdreview.com/our-revi...-review-512gb/

Paul

Paul,

Have no idea why you would expect the SSD to be isolated from case
ground. Everything in the computer and the case itself is tied to the
grid ground. Mount a motherboard and the mounting screws screw into the
case as well as the screw heads tighten down on ground pads on the
motherboard. SSD's are also grounded when placed in a mounting tray to
case ground.

As for the longer pins on power and data connectors, the pins that are
designated as ground pins are longer to insure a ground connection is
made before any data pins mate to prevent static discharges. This pin
design also accommodates "hot swap" capable devices such as hard drives
and SSD's.

While it's always good practice to use measures to prevent ESD when
mounting a device such as a SSD, do not isolate it from the mounting
mechanisms such as placing an insulator between it and a metal case.
Depending on the SSD (some cases are plastic), the metal case is the heat
sink as shown in the link you included in your post. Please note that
the logic board is held in-place by a screw in the back that fastens to
the SSD case and tightens against a ground pad on the SSD logic board.

There are two ground philosophies for protecting assemblies
from ESD.

Neither was followed in this case.

Paul

Paul,

Not sure I follow your logic on this. The OP said he had his case grounded
to a copper pipe. What wasn't stated is how his power supply is grounded or
if it was even plugged in. In the US, the 3rd lug on a plug is the green
(safety) ground and in a typical home wiring setup, the white wire and green
are tied to a single bus bar in the distribution panel so as to prevent
ground loops / current loops.

So while his setup using a ground from the case to a copper water pipe could
potentially create a ground loop if there were other wiring problems, it
still is ground as long as there's no interruption to earth ground in that
copper pipe and in his wiring and would dissipate any ESD charge.

Potential for ESD would be from him picking up the SSD and then plugging it
in before he touched the case (grounding himself) and creating a arc between
his hand holding the SSD and getting the data or power connectors close
enough so the static potential went from him to the ground pins on the cable
or the case.

That’s' why the manufactures include warnings about using ground straps
and/or touching the case before working on it. What people don't realize is
that usually, they unplug the power cord from the wall or the power supply
and that’s when their case is no longer grounded. But in the OP's situation,
he had an additional ground to a water pipe. That may or may not be a good
situation depending on his house wiring and I've never seen a power supply
plug without a polarized plug. Now if the wall socket (old house wiring)
does not have a safety ground, then his water pipe ground is a good idea.

I've worked at radar sites and on some of the largest computer installations
in the world and worked worked with power engineers that specialize in how
"all things" need to be grounded and why. It is a complicated field of
study and ESD can create havoc on computer components when you have
thousands of volts jumping between you and the computer.

So I'm not trying to argue with you but saying "Neither was followed in this
case" didn't make sense to me. Perhaps you could expand on the "Neither" a
bit. I'm not sure if you are referring to the OP or to your own situation.
If it's your own, then I'll shut up and sit down cause I don't know what or
how you were doing your measurements.

The new copper water pipe is near the computer, so I just clipped to
it a wire connected to the computer case. Insurance, that's all.

On 4/16/2018 9:00 AM, Wolf K wrote:
On 2018-04-16 02:32, Peter Jason wrote:
[...]
The new copper water pipe is near the computer, so I just clipped to
it a wire connected to the computer case.Â*Â* Insurance, that's all.

As others have pointed out, that's like grounding the case after you've
unplugged the power cord, which has a ground wire, and grounds the case
as ;long as the cord is connected. Nowadays, house wiring is no longer
grounded to the water lines: IIRC, the grounding is done at the entry
point, at the meter.

Thus, the house wiring is grounded via the grid. Since there can be
inadvertent grounding, we have ground-fault detector-equipped wall
plugs. Code here requires all external and bathroom/kitchen pugs to be
ground-fault detectors. These detect a grounded current leak that
bypasses the whole-house grounding, and disconnect the plug internally.
That's why I'm uncertain about whether your "insurance" is a good idea.

I'd like to know. :-)

PS: First house we owned grounded the panel to the waterline. But the
wiring was two-wire, no ground. Unpolarised, too.

Having equipment grounded to differ ground points can be as dangerous as
having no ground at all.

As stated in previous post, modern house is grounded to a point common
to all outlets in the house.

With different ground points you can actually have a potential
difference between the ground points which can cause currents where the
two grounds come together, ie your computer.

When we installed the LAN at a company I worked at, we spent a
considerable amount of money insuring there was zero potential between
the points where the all computers were attached to the LAN.

With the shrinking power needs for modern electronics, I have often
wonder if the potential difference could be used to run some small
electronic devices, and do away with the need for batteries



--
2018: The year we learn to play the great game of Euchre

On 04/15/2018 11:12 PM, Paul wrote:
Bob_S wrote:
"Paul"Â* wrote in message news

Bob_S wrote:
"Paul"Â* wrote in message news
Peter Jason wrote:
On Sat, 14 Apr 2018 22:25:50 -0400, Paul
wrote:

Peter Jason wrote:
My computer case is of Aluminium and earthed to a domestic copper
water pipe. , the casing of the Samsungs SSDs seem to be anodized
aluminium.Â* Since my computer case is old it has no provision
for 2.5"
SSDs I have them resting on an aluminium surface.Â*Â* Is this a
problem?
I assume the SSDs have internal insulation.
I just measured a couple SSDs here, and son of a bitch,
there's a hard connection between SSD casing and logic ground!

That's not supposed to be good for ESD handling.

I was expecting to find a 1 megohm connection between
aluminum SSD casing and the logic ground on the SSD.

But it's a hard short.

*******

The chassis of your computer case, runs at logic ground
potential.

The casing of your SSD, runs at logic ground potential.

This means you can safely rest the SSD on the bottom of
the computer case, without any "thru" current flowing.

Just don't touch a 3.3V, 5V, or 12V pin from some
Molex connector, to the chassis of the SSD. Since
it's a hard ground, we can't be carelessly resting
a Molex power pin in contact (somehow) with the chassis.

While the pins on Molex are flush or
slightly recessed, there might be some conceivable
way for something to touch. And my finding a
hard ground on the SSD chassis, is not a good
thing.

I'll be extra careful in future, to keep Molex
away from it.

I was really expecting to find a 1Megohm (high resistance)
drain between shiny aluminum SSD casing and the logic
ground next to the data pins of the SSD.

Â*Â*Â* GNDÂ*Â*Â*Â*Â*Â*Â*Â* GNDÂ*Â*Â*Â*Â*Â*Â*Â* GNDÂ*Â*Â* === logic ground pins are longer
Â*Â*Â*Â*Â*Â*Â* tx+ tx-Â*Â*Â*Â* rx+ rx-Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* on the SSD connector. The
data
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* pins on the 7 pin data are
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* recessed. Check with the
ohmmeter,
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* between GND and chassis,
and you'll
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* see the hard short I
measured.

Summary:

1) Safe to rest SSD on bottom of computer case, no matter
Â*Â* what the casing is made of.

2) Don't touch any "hot" Molex pins, to the SSD housing.
Â*Â* Just like you would not touch any "hot" Molex pins,
Â*Â* to the computer case metal posts. The motherboard has a hard
Â*Â* short to the chassis, through the standoffs. Most everything
Â*Â* in the computer, has a hard ground. The only poorly designed
Â*Â* feature, is "plastic fascia" on the front of the computer,
Â*Â* around front USB ports, which is a poor way to handle ESD issues.

3) Don't scuff across the carpet and pick up your
Â*Â* SSD by the aluminum casing. Keep unused SSDs in an ESD bag,
Â*Â* scuff across the carpet if you must, pick up the
Â*Â* SSD by the ESD bag, touch the ESD bag plastic on
Â*Â* the inside of the bag, to bring yourself and the bag contents
Â*Â* to the same potential. With your other hand, touch
Â*Â* the computer chassis. Now, everything is "drained" to
Â*Â* the same electrostatic potential, you can remove the
Â*Â* SSD from the ESD bag, and connect it to SATA power
Â*Â* and SATA data.

Â*Â* By using the series resistance of the ESD bag, to limit
Â*Â* ESD current flow, you're *safely* bringing the SSD up
Â*Â* to the same electrostatic potential as the thing you
Â*Â* wish to connect it to.

Note: I just changed my handling procedure! as a result
Â*Â*Â*Â*Â* of this ohmmeter measurement. I'd assumed SSD chassis
Â*Â*Â*Â*Â* were drain connected, not "hard" connected. Now I
Â*Â*Â*Â*Â* will have to start using ESD bags for them, just as
Â*Â*Â*Â*Â* I do for hard drives.

Â*Â* Paul


Thanks Paul.Â* I have put my SSDs in plastic sleeves, and rested this
combination on cardboard.Â*Â* I thought this might be the cause of my
computer restarts.Â*Â* Also I have disabled all "fast startups" via the
registry.

I wouldn't entirely insulate the thing. Some SSDs have
high peak power usage (SandForce compression), and they
get a little warm.

Put a cardboard underneath if you like. Leave
at least one metal surface for cooling.

In this review, you can see (and it's mentioned in the text),
that thermal pads were used on all the NAND chips. That means
both metal surfaces are used for their slight cooling advantage.

http://www.thessdreview.com/our-revi...-review-512gb/


Â*Â* Paul

Paul,

Have no idea why you would expect the SSD to be isolated from case
ground. Everything in the computer and the case itself is tied to
the grid ground. Mount a motherboard and the mounting screws screw
into the case as well as the screw heads tighten down on ground pads
on the motherboard.Â* SSD's are also grounded when placed in a
mounting tray to case ground.

As for the longer pins on power and data connectors, the pins that
are designated as ground pins are longer to insure a ground
connection is made before any data pins mate to prevent static
discharges.Â* This pin design also accommodates "hot swap" capable
devices such as hard drives and SSD's.

While it's always good practice to use measures to prevent ESD when
mounting a device such as a SSD, do not isolate it from the mounting
mechanisms such as placing an insulator between it and a metal case.
Depending on the SSD (some cases are plastic), the metal case is the
heat sink as shown in the link you included in your post.Â* Please
note that the logic board is held in-place by a screw in the back
that fastens to the SSD case and tightens against a ground pad on
the SSD logic board.

There are two ground philosophies for protecting assemblies
from ESD.

Neither was followed in this case.

Â*Â* Paul

Paul,

Not sure I follow your logic on this. The OP said he had his case
grounded to a copper pipe.Â* What wasn't stated is how his power supply
is grounded or if it was even plugged in.Â* In the US, the 3rd lug on a
plug is the green (safety) ground and in a typical home wiring setup,
the white wire and green are tied to a single bus bar in the
distribution panel so as to prevent ground loops / current loops.

So while his setup using a ground from the case to a copper water pipe
could potentially create a ground loop if there were other wiring
problems, it still is ground as long as there's no interruption to
earth ground in that copper pipe and in his wiring and would dissipate
any ESD charge.

Potential for ESD would be from him picking up the SSD and then
plugging it in before he touched the case (grounding himself) and
creating a arc between his hand holding the SSD and getting the data
or power connectors close enough so the static potential went from him
to the ground pins on the cable or the case.

That’s' why the manufactures include warnings about using ground
straps and/or touching the case before working on it.Â* What people
don't realize is that usually, they unplug the power cord from the
wall or the power supply and that’s when their case is no longer
grounded. But in the OP's situation, he had an additional ground to a
water pipe.Â* That may or may not be a good situation depending on his
house wiring and I've never seen a power supply plug without a
polarized plug.Â*Â* Now if the wall socket (old house wiring) does not
have a safety ground, then his water pipe ground is a good idea.

I've worked at radar sites and on some of the largest computer
installations in the world and worked worked with power engineers that
specialize in how "all things" need to be grounded and why.Â* It is a
complicated field of study and ESD can create havoc on computer
components when you have thousands of volts jumping between you and
the computer.

So I'm not trying to argue with you but saying "Neither was followed
in this case" didn't make sense to me.Â* Perhaps you could expand on
the "Neither" a bit.Â* I'm not sure if you are referring to the OP or
to your own situation. If it's your own, then I'll shut up and sit
down cause I don't know what or how you were doing your measurements.

1) There's no such thing as "ground". The earth is an insulated
Â*Â* ball floating in the vacuum of space. The earth is merely
Â*Â* a "reference point". It has no special properties as such.
Â*Â* "Standing on dirt is not magic." But since we are in frequent
Â*Â* contact with dirt though, it's in our best interest to not
Â*Â* touch potentials higher or lower than that potential. We could
Â*Â* get a shock.

2) To avoid ESD, bring all assemblies to "equipotential".
Â*Â* That's the trick.

If I unplug a PC from the wall, remove all cabling,
I can still *safely* install hardware in it, as long
as I follow equipotential rules. This means opening
the ESD bag but not removing the new hardware. Touch the
inside of the bag while touching the chassis. It helps
if you wear short pants and lay the metal-bodied PC flat
on your lap while working (that's if you don't own an ESD strap).

By bringing the PC, the new hardware item, and you to the
same electrostatic potential, there is no danger of ESD
damage.

And notice in that picture, there is *no* connection to
earth ground, safety ground, cold water pipes or anything.
You make an "electrostatic island" of yourself, then ensure
that all entities are "charged to the same level".

I could place my work chair on glass blocks, charge
myself to 50kV ESD level, and as long as I followed
the rules about touching the inside of the ESD bag to
bring the bag to the same potential as the other
kit, I can actually install something without damage.

The usage of ESD straps (where the ESD strap is fastened
to the case via a 10meg series resistor), is for a similar
purpose. It's not ground - it's a way to bring the
computer chassis and any other objects used in the
operation, to the same electrostatic potential. The
series resistor inside the strap, performs the same
function as the "resistive" surface inside the
ESD bag. It's a dissipative path, that limits the
ESD peak current flow level.

By placing a hard connection between the metal chassis
of the SSD and logic ground, now we have to resort
to ESD bags again, as there is no dissipative path
to logic ground. I can't really afford to scuff across
the carpet, and discharge 50kV into the SSD chassis,
because the result will now be unknown (I won't know
whether I could have damaged it or not, and it
could depend on the way the PCB and mount points are
designed). If the connection between SSD chassis
and PCB was dissipative, then I'd know there was
no possibility of a high "peak" current flow during
equalization. If the SSD chassis was plastic, I would
be using the second philosophy, which says "don't allow
static to dissipate into the item at all". Then the
advanced ground contacts take the brunt of the
equalization current flow.

And things like this aren't left to chance in the lab.
If I wanted to be sure my decision about the hard
ground on the SSD wasn't a mistake, I do this
kind of testing. We test for upset level. We
test for damage level (which is actually pretty
hard to determine, what constitutes "damage").
The bad thing about ESD, is you can "weaken" a
piece of silicon, which weeks later, decides to
completely fail. And then it's hard to trace back
exactly when you "broke it".

https://en.wikipedia.org/wiki/Human-body_model

These have changed, since the last time I tried this stuff.
We had a nasty gadget for doing up to 15kV tests on
our products. This is so much more "refined" looking.

https://transientspecialists.com/pro...contact-mode-1


There are two ways to damage things with ESD. One is
via direct discharge. The other is via "induction". When
usage of an improperly designed front USB solution blows
out the pad I/O, it's just as likely the transient
traveling down the black wire, "induces" a potential
in D+ and D-, and blows out the driver pad. When you do ESD
analysis, the danger isn't always from the direct path.

I will be switching to ESD bags from now on, for my
SSDs, and bringing myself to the same potential as the
chassis. (The same kind of gymnastics you do, when you
don't have an ESD strap handy.) It's not because I know
for a fact the SSD will fail. It's because I don't really
know, for any individual SSD, whether it has a particular
vulnerability or not. If I had a pile of these in the lab,
and an HBM-type tester, I could take a shot at finding out.

Â*Â* Paul

Here's an extreme example.

Rene

Wolf K wrote:
On 2018-04-16 02:32, Peter Jason wrote:
[...]
The new copper water pipe is near the computer, so I just clipped to
it a wire connected to the computer case. Insurance, that's all.

As others have pointed out, that's like grounding the case after you've
unplugged the power cord, which has a ground wire, and grounds the case
as ;long as the cord is connected. Nowadays, house wiring is no longer
grounded to the water lines: IIRC, the grounding is done at the entry
point, at the meter.

Thus, the house wiring is grounded via the grid. Since there can be
inadvertent grounding, we have ground-fault detector-equipped wall
plugs. Code here requires all external and bathroom/kitchen pugs to be
ground-fault detectors. These detect a grounded current leak that
bypasses the whole-house grounding, and disconnect the plug internally.
That's why I'm uncertain about whether your "insurance" is a good idea.

I'd like to know. :-)

PS: First house we owned grounded the panel to the waterline. But the
wiring was two-wire, no ground. Unpolarised, too.


I'm not an electrician, but I don't think Safety Ground
comes from the grid.

In the diagram here, the House near the guys name "Gene",
you can see a ground rod just outside the house. I think
that's Safety Ground, which is not exactly the same thing
as Neutral. Neutral and Safety Ground should be close
in potential (~1V say), but aren't always exactly the
same thing. And under fault conditions, Neutral could
end up at just about any potential. That's why you don't
necessarily want to use Neutral as a "cheap chassis ground".

http://indexxit.com/wp-content/uploa...ru-970x912.jpg

And some distribution systems, don't use the Neutral idea.
They actually have the whole return current flow through Earth.
What happens to your Safety Ground, on a system like this ?
Must depend on where exactly, you drive the rod.

https://en.wikipedia.org/wiki/Single-wire_earth_return

And when it comes to "rods", the practice isn't the same
all over the continent. Some areas have poor soil conditions,
and multiple rods are required. Only a local electrician
will know the "local rules". And nobody actually wants
grounding rods that require "maintenance", because nobody
would tell the owner about that. Who would suspect they're
expected to look after their ground ?

Paul

On 04/16/2018 9:57 AM, Paul wrote:
Wolf K wrote:
On 2018-04-16 02:32, Peter Jason wrote:
[...]
The new copper water pipe is near the computer, so I just clipped to
it a wire connected to the computer case.Â*Â* Insurance, that's all.

As others have pointed out, that's like grounding the case after
you've unplugged the power cord, which has a ground wire, and grounds
the case as ;long as the cord is connected. Nowadays, house wiring is
no longer grounded to the water lines: IIRC, the grounding is done at
the entry point, at the meter.

Thus, the house wiring is grounded via the grid. Since there can be
inadvertent grounding, we have ground-fault detector-equipped wall
plugs. Code here requires all external and bathroom/kitchen pugs to be
ground-fault detectors. These detect a grounded current leak that
bypasses the whole-house grounding, and disconnect the plug
internally. That's why I'm uncertain about whether your "insurance" is
a good idea.

I'd like to know. :-)

PS: First house we owned grounded the panel to the waterline. But the
wiring was two-wire, no ground. Unpolarised, too.


I'm not an electrician, but I don't think Safety Ground
comes from the grid.

In the diagram here, the House near the guys name "Gene",
you can see a ground rod just outside the house. I think
that's Safety Ground, which is not exactly the same thing
as Neutral. Neutral and Safety Ground should be close
in potential (~1V say), but aren't always exactly the
same thing. And under fault conditions, Neutral could
end up at just about any potential. That's why you don't
necessarily want to use Neutral as a "cheap chassis ground".

http://indexxit.com/wp-content/uploa...ru-970x912.jpg


And some distribution systems, don't use the Neutral idea.
They actually have the whole return current flow through Earth.
What happens to your Safety Ground, on a system like this ?
Must depend on where exactly, you drive the rod.

https://en.wikipedia.org/wiki/Single-wire_earth_return

And when it comes to "rods", the practice isn't the same
all over the continent. Some areas have poor soil conditions,
and multiple rods are required. Only a local electrician
will know the "local rules". And nobody actually wants
grounding rods that require "maintenance", because nobody
would tell the owner about that. Who would suspect they're
expected to look after their ground ?

Â*Â* Paul

Where I was brought up on my dads farm in Saskatchewan about 1952,
Electric power was installed to the local farms with a single conductor
to the yard pole and 2 copper rods about ten feet long where driven into
the ground at the pole to use the earth as the neutral conductor.

Rene

Rene Lamontagne wrote:
On 04/16/2018 9:57 AM, Paul wrote:
Wolf K wrote:
On 2018-04-16 02:32, Peter Jason wrote:
[...]
The new copper water pipe is near the computer, so I just clipped to
it a wire connected to the computer case. Insurance, that's all.

As others have pointed out, that's like grounding the case after
you've unplugged the power cord, which has a ground wire, and grounds
the case as ;long as the cord is connected. Nowadays, house wiring is
no longer grounded to the water lines: IIRC, the grounding is done at
the entry point, at the meter.

Thus, the house wiring is grounded via the grid. Since there can be
inadvertent grounding, we have ground-fault detector-equipped wall
plugs. Code here requires all external and bathroom/kitchen pugs to
be ground-fault detectors. These detect a grounded current leak that
bypasses the whole-house grounding, and disconnect the plug
internally. That's why I'm uncertain about whether your "insurance"
is a good idea.

I'd like to know. :-)

PS: First house we owned grounded the panel to the waterline. But the
wiring was two-wire, no ground. Unpolarised, too.


I'm not an electrician, but I don't think Safety Ground
comes from the grid.

In the diagram here, the House near the guys name "Gene",
you can see a ground rod just outside the house. I think
that's Safety Ground, which is not exactly the same thing
as Neutral. Neutral and Safety Ground should be close
in potential (~1V say), but aren't always exactly the
same thing. And under fault conditions, Neutral could
end up at just about any potential. That's why you don't
necessarily want to use Neutral as a "cheap chassis ground".

http://indexxit.com/wp-content/uploa...ru-970x912.jpg


And some distribution systems, don't use the Neutral idea.
They actually have the whole return current flow through Earth.
What happens to your Safety Ground, on a system like this ?
Must depend on where exactly, you drive the rod.

https://en.wikipedia.org/wiki/Single-wire_earth_return

And when it comes to "rods", the practice isn't the same
all over the continent. Some areas have poor soil conditions,
and multiple rods are required. Only a local electrician
will know the "local rules". And nobody actually wants
grounding rods that require "maintenance", because nobody
would tell the owner about that. Who would suspect they're
expected to look after their ground ?

Paul

Where I was brought up on my dads farm in Saskatchewan about 1952,
Electric power was installed to the local farms with a single conductor
to the yard pole and 2 copper rods about ten feet long where driven into
the ground at the pole to use the earth as the neutral conductor.

Rene

Were there ever any surprised ?

Unhappy cows in the milking parlor ?

Apparently cows don't like receiving an electric shock through
the udder, from the milking machine :-) And apparently a tiny
potential difference is enough to do it (1V level).

Paul

On 04/16/2018 10:26 AM, Paul wrote:
Rene Lamontagne wrote:
On 04/16/2018 9:57 AM, Paul wrote:
Wolf K wrote:
On 2018-04-16 02:32, Peter Jason wrote:
[...]
The new copper water pipe is near the computer, so I just clipped to
it a wire connected to the computer case.Â*Â* Insurance, that's all.

As others have pointed out, that's like grounding the case after
you've unplugged the power cord, which has a ground wire, and
grounds the case as ;long as the cord is connected. Nowadays, house
wiring is no longer grounded to the water lines: IIRC, the grounding
is done at the entry point, at the meter.

Thus, the house wiring is grounded via the grid. Since there can be
inadvertent grounding, we have ground-fault detector-equipped wall
plugs. Code here requires all external and bathroom/kitchen pugs to
be ground-fault detectors. These detect a grounded current leak that
bypasses the whole-house grounding, and disconnect the plug
internally. That's why I'm uncertain about whether your "insurance"
is a good idea.

I'd like to know. :-)

PS: First house we owned grounded the panel to the waterline. But
the wiring was two-wire, no ground. Unpolarised, too.


I'm not an electrician, but I don't think Safety Ground
comes from the grid.

In the diagram here, the House near the guys name "Gene",
you can see a ground rod just outside the house. I think
that's Safety Ground, which is not exactly the same thing
as Neutral. Neutral and Safety Ground should be close
in potential (~1V say), but aren't always exactly the
same thing. And under fault conditions, Neutral could
end up at just about any potential. That's why you don't
necessarily want to use Neutral as a "cheap chassis ground".

http://indexxit.com/wp-content/uploa...ru-970x912.jpg


And some distribution systems, don't use the Neutral idea.
They actually have the whole return current flow through Earth.
What happens to your Safety Ground, on a system like this ?
Must depend on where exactly, you drive the rod.

https://en.wikipedia.org/wiki/Single-wire_earth_return

And when it comes to "rods", the practice isn't the same
all over the continent. Some areas have poor soil conditions,
and multiple rods are required. Only a local electrician
will know the "local rules". And nobody actually wants
grounding rods that require "maintenance", because nobody
would tell the owner about that. Who would suspect they're
expected to look after their ground ?

Â*Â*Â* Paul

Where I was brought up on my dads farm in Saskatchewan about 1952,
Electric power was installed to the local farms with a single
conductor to the yard pole and 2 copper rods about ten feet long where
driven into the ground at the pole to use the earth as the neutral
conductor.

Rene

Were there ever any surprised ?

Unhappy cows in the milking parlor ?

Apparently cows don't like receiving an electric shock through
the udder, from the milking machine :-) And apparently a tiny
potential difference is enough to do it (1V level).

Â*Â* Paul


No, no surprises, everything worked as expected.
The cows were all happy as we hand milked them, no electric milking
machines like nowadays. to this day I remember squirting milk into the
cats faces and ****ing them off... :-)

Rene

On Sun, 15 Apr 2018 10:50:46 -0600, ken1943
wrote:

On Sun, 15 Apr 2018 08:32:03 -0700, Ken Blake
wrote:

On Sun, 15 Apr 2018 09:25:01 -0600, ken1943
wrote:


Go to Amazon.com and buy an SSD tray or mounting bracket for each SSD
you have. They are only a few dollars each and will let you install
the SSDs in 3.5" drive bays.

I wrapped one in bubble wrap and stuck in a 3.5 bay.



Do they get hot? I don't know for sure, but if they do, what you did
could start a fire.

They run cool. Check specs. on one, they only draw under 2-4 watts for
the size I use. Probably depends on how many chips/capacity one has.



I would still worry about fires. Even if they run cool, something else
near them may run hot.

As far as I'm concerned, putting anything flammable inside the case is
a bad idea.

"Paul" wrote in message news

Bob_S wrote:
"Paul" wrote in message news

Bob_S wrote:
"Paul" wrote in message news
Peter Jason wrote:
On Sat, 14 Apr 2018 22:25:50 -0400, Paul
wrote:

Peter Jason wrote:
My computer case is of Aluminium and earthed to a domestic copper
water pipe. , the casing of the Samsungs SSDs seem to be anodized
aluminium. Since my computer case is old it has no provision for
2.5"
SSDs I have them resting on an aluminium surface. Is this a
problem?
I assume the SSDs have internal insulation.
I just measured a couple SSDs here, and son of a bitch,
there's a hard connection between SSD casing and logic ground!

That's not supposed to be good for ESD handling.

I was expecting to find a 1 megohm connection between
aluminum SSD casing and the logic ground on the SSD.

But it's a hard short.

*******

The chassis of your computer case, runs at logic ground
potential.

The casing of your SSD, runs at logic ground potential.

This means you can safely rest the SSD on the bottom of
the computer case, without any "thru" current flowing.

Just don't touch a 3.3V, 5V, or 12V pin from some
Molex connector, to the chassis of the SSD. Since
it's a hard ground, we can't be carelessly resting
a Molex power pin in contact (somehow) with the chassis.

While the pins on Molex are flush or
slightly recessed, there might be some conceivable
way for something to touch. And my finding a
hard ground on the SSD chassis, is not a good
thing.

I'll be extra careful in future, to keep Molex
away from it.

I was really expecting to find a 1Megohm (high resistance)
drain between shiny aluminum SSD casing and the logic
ground next to the data pins of the SSD.

GND GND GND === logic ground pins are longer
tx+ tx- rx+ rx- on the SSD connector. The
data
pins on the 7 pin data are
recessed. Check with the
ohmmeter,
between GND and chassis, and
you'll
see the hard short I
measured.

Summary:

1) Safe to rest SSD on bottom of computer case, no matter
what the casing is made of.

2) Don't touch any "hot" Molex pins, to the SSD housing.
Just like you would not touch any "hot" Molex pins,
to the computer case metal posts. The motherboard has a hard
short to the chassis, through the standoffs. Most everything
in the computer, has a hard ground. The only poorly designed
feature, is "plastic fascia" on the front of the computer,
around front USB ports, which is a poor way to handle ESD issues.

3) Don't scuff across the carpet and pick up your
SSD by the aluminum casing. Keep unused SSDs in an ESD bag,
scuff across the carpet if you must, pick up the
SSD by the ESD bag, touch the ESD bag plastic on
the inside of the bag, to bring yourself and the bag contents
to the same potential. With your other hand, touch
the computer chassis. Now, everything is "drained" to
the same electrostatic potential, you can remove the
SSD from the ESD bag, and connect it to SATA power
and SATA data.

By using the series resistance of the ESD bag, to limit
ESD current flow, you're *safely* bringing the SSD up
to the same electrostatic potential as the thing you
wish to connect it to.

Note: I just changed my handling procedure! as a result
of this ohmmeter measurement. I'd assumed SSD chassis
were drain connected, not "hard" connected. Now I
will have to start using ESD bags for them, just as
I do for hard drives.

Paul


Thanks Paul. I have put my SSDs in plastic sleeves, and rested this
combination on cardboard. I thought this might be the cause of my
computer restarts. Also I have disabled all "fast startups" via the
registry.

I wouldn't entirely insulate the thing. Some SSDs have
high peak power usage (SandForce compression), and they
get a little warm.

Put a cardboard underneath if you like. Leave
at least one metal surface for cooling.

In this review, you can see (and it's mentioned in the text),
that thermal pads were used on all the NAND chips. That means
both metal surfaces are used for their slight cooling advantage.

http://www.thessdreview.com/our-revi...-review-512gb/

Paul

Paul,

Have no idea why you would expect the SSD to be isolated from case
ground. Everything in the computer and the case itself is tied to the
grid ground. Mount a motherboard and the mounting screws screw into the
case as well as the screw heads tighten down on ground pads on the
motherboard. SSD's are also grounded when placed in a mounting tray to
case ground.

As for the longer pins on power and data connectors, the pins that are
designated as ground pins are longer to insure a ground connection is
made before any data pins mate to prevent static discharges. This pin
design also accommodates "hot swap" capable devices such as hard drives
and SSD's.

While it's always good practice to use measures to prevent ESD when
mounting a device such as a SSD, do not isolate it from the mounting
mechanisms such as placing an insulator between it and a metal case.
Depending on the SSD (some cases are plastic), the metal case is the
heat sink as shown in the link you included in your post. Please note
that the logic board is held in-place by a screw in the back that
fastens to the SSD case and tightens against a ground pad on the SSD
logic board.

There are two ground philosophies for protecting assemblies
from ESD.

Neither was followed in this case.

Paul

Paul,

Not sure I follow your logic on this. The OP said he had his case
grounded to a copper pipe. What wasn't stated is how his power supply is
grounded or if it was even plugged in. In the US, the 3rd lug on a plug
is the green (safety) ground and in a typical home wiring setup, the
white wire and green are tied to a single bus bar in the distribution
panel so as to prevent ground loops / current loops.

So while his setup using a ground from the case to a copper water pipe
could potentially create a ground loop if there were other wiring
problems, it still is ground as long as there's no interruption to earth
ground in that copper pipe and in his wiring and would dissipate any ESD
charge.

Potential for ESD would be from him picking up the SSD and then plugging
it in before he touched the case (grounding himself) and creating a arc
between his hand holding the SSD and getting the data or power connectors
close enough so the static potential went from him to the ground pins on
the cable or the case.

That’s' why the manufactures include warnings about using ground straps
and/or touching the case before working on it. What people don't realize
is that usually, they unplug the power cord from the wall or the power
supply and that’s when their case is no longer grounded. But in the OP's
situation, he had an additional ground to a water pipe. That may or may
not be a good situation depending on his house wiring and I've never seen
a power supply plug without a polarized plug. Now if the wall socket
(old house wiring) does not have a safety ground, then his water pipe
ground is a good idea.

I've worked at radar sites and on some of the largest computer
installations in the world and worked worked with power engineers that
specialize in how "all things" need to be grounded and why. It is a
complicated field of study and ESD can create havoc on computer
components when you have thousands of volts jumping between you and the
computer.

So I'm not trying to argue with you but saying "Neither was followed in
this case" didn't make sense to me. Perhaps you could expand on the
"Neither" a bit. I'm not sure if you are referring to the OP or to your
own situation. If it's your own, then I'll shut up and sit down cause I
don't know what or how you were doing your measurements.

1) There's no such thing as "ground". The earth is an insulated
ball floating in the vacuum of space. The earth is merely
a "reference point". It has no special properties as such.
"Standing on dirt is not magic." But since we are in frequent
contact with dirt though, it's in our best interest to not
touch potentials higher or lower than that potential. We could
get a shock.

2) To avoid ESD, bring all assemblies to "equipotential".
That's the trick.

If I unplug a PC from the wall, remove all cabling,
I can still *safely* install hardware in it, as long
as I follow equipotential rules. This means opening
the ESD bag but not removing the new hardware. Touch the
inside of the bag while touching the chassis. It helps
if you wear short pants and lay the metal-bodied PC flat
on your lap while working (that's if you don't own an ESD strap).

By bringing the PC, the new hardware item, and you to the
same electrostatic potential, there is no danger of ESD
damage.

And notice in that picture, there is *no* connection to
earth ground, safety ground, cold water pipes or anything.
You make an "electrostatic island" of yourself, then ensure
that all entities are "charged to the same level".

I could place my work chair on glass blocks, charge
myself to 50kV ESD level, and as long as I followed
the rules about touching the inside of the ESD bag to
bring the bag to the same potential as the other
kit, I can actually install something without damage.

The usage of ESD straps (where the ESD strap is fastened
to the case via a 10meg series resistor), is for a similar
purpose. It's not ground - it's a way to bring the
computer chassis and any other objects used in the
operation, to the same electrostatic potential. The
series resistor inside the strap, performs the same
function as the "resistive" surface inside the
ESD bag. It's a dissipative path, that limits the
ESD peak current flow level.

By placing a hard connection between the metal chassis
of the SSD and logic ground, now we have to resort
to ESD bags again, as there is no dissipative path
to logic ground. I can't really afford to scuff across
the carpet, and discharge 50kV into the SSD chassis,
because the result will now be unknown (I won't know
whether I could have damaged it or not, and it
could depend on the way the PCB and mount points are
designed). If the connection between SSD chassis
and PCB was dissipative, then I'd know there was
no possibility of a high "peak" current flow during
equalization. If the SSD chassis was plastic, I would
be using the second philosophy, which says "don't allow
static to dissipate into the item at all". Then the
advanced ground contacts take the brunt of the
equalization current flow.

And things like this aren't left to chance in the lab.
If I wanted to be sure my decision about the hard
ground on the SSD wasn't a mistake, I do this
kind of testing. We test for upset level. We
test for damage level (which is actually pretty
hard to determine, what constitutes "damage").
The bad thing about ESD, is you can "weaken" a
piece of silicon, which weeks later, decides to
completely fail. And then it's hard to trace back
exactly when you "broke it".

https://en.wikipedia.org/wiki/Human-body_model

These have changed, since the last time I tried this stuff.
We had a nasty gadget for doing up to 15kV tests on
our products. This is so much more "refined" looking.

https://transientspecialists.com/pro...contact-mode-1

There are two ways to damage things with ESD. One is
via direct discharge. The other is via "induction". When
usage of an improperly designed front USB solution blows
out the pad I/O, it's just as likely the transient
traveling down the black wire, "induces" a potential
in D+ and D-, and blows out the driver pad. When you do ESD
analysis, the danger isn't always from the direct path.

I will be switching to ESD bags from now on, for my
SSDs, and bringing myself to the same potential as the
chassis. (The same kind of gymnastics you do, when you
don't have an ESD strap handy.) It's not because I know
for a fact the SSD will fail. It's because I don't really
know, for any individual SSD, whether it has a particular
vulnerability or not. If I had a pile of these in the lab,
and an HBM-type tester, I could take a shot at finding out.

Paul


Paul - now you're being an ass who thinks he knows everything. Here's a clue
for you - you don't, so stop acting like it.

We come here to share knowledge - not to boost your friggin ego.


--


Bob S.

Bob_S wrote:

Paul - now you're being an ass who thinks he knows everything. Here's a
clue for you - you don't, so stop acting like it.

We come here to share knowledge - not to boost your friggin ego.

But there is a lesson here. For ESD protection, there is the
concept of equipotential. If two assemblies have exactly the
same potential, no damaging currents flow into semiconductors.

This is how and why ESD-protected labs are designed the way they
are. There are high-resistance paths everything in the lab, so
that everything is brought to the same potential safelt. If I
lay my SSD on the ESD mat on the benchtop, or on the ESD flooring,
they're all charged to the same potential. I snap on my ESD
strap, to bring myself to the same potential as the mat, before
I start work on something.

Ground is just a reference point. Nothing more. It's used
as a return path for power systems (a conductor-of-convenience).
Similar in a way, to how the metalwork in your car, forms the
second wire for DC power distribution inside the car.

And I gave a practical example. To work safely, wear short pants
with exposed leg skin. Put the desktop PC on its side on your lap.
Now, touch the inside of the ESD bag first, then pull out an item,
install. It's like your own ESD-proof lab, in miniature. You can
do a whole build that way.

Paul

On 04/16/2018 9:39 PM, Paul wrote:
Bob_S wrote:

Paul - now you're being an ass who thinks he knows everything. Here's
a clue for you - you don't, so stop acting like it.

We come here to share knowledge - not to boost your friggin ego.

But there is a lesson here. For ESD protection, there is the
concept of equipotential. If two assemblies have exactly the
same potential, no damaging currents flow into semiconductors.

This is how and why ESD-protected labs are designed the way they
are. There are high-resistance paths everything in the lab, so
that everything is brought to the same potential safelt. If I
lay my SSD on the ESD mat on the benchtop, or on the ESD flooring,
they're all charged to the same potential. I snap on my ESD
strap, to bring myself to the same potential as the mat, before
I start work on something.

Ground is just a reference point. Nothing more. It's used
as a return path for power systems (a conductor-of-convenience).
Similar in a way, to how the metalwork in your car, forms the
second wire for DC power distribution inside the car.

And I gave a practical example. To work safely, wear short pants
with exposed leg skin. Put the desktop PC on its side on your lap.
Now, touch the inside of the ESD bag first, then pull out an item,
install. It's like your own ESD-proof lab, in miniature. You can
do a whole build that way.

Â*Â* Paul

Thanks Paul for the Great ESD tips, My earlier post was screwed up with
the extreme example, I somehow lost the link I was trying to include.

I'll try again.

https://www.youtube.com/watch?v=x94BH9TUiHM

hope that one hangs in there.

Rene

Rene Lamontagne wrote:
On 04/16/2018 9:39 PM, Paul wrote:
Bob_S wrote:

Paul - now you're being an ass who thinks he knows everything. Here's
a clue for you - you don't, so stop acting like it.

We come here to share knowledge - not to boost your friggin ego.

But there is a lesson here. For ESD protection, there is the
concept of equipotential. If two assemblies have exactly the
same potential, no damaging currents flow into semiconductors.

This is how and why ESD-protected labs are designed the way they
are. There are high-resistance paths everything in the lab, so
that everything is brought to the same potential safelt. If I
lay my SSD on the ESD mat on the benchtop, or on the ESD flooring,
they're all charged to the same potential. I snap on my ESD
strap, to bring myself to the same potential as the mat, before
I start work on something.

Ground is just a reference point. Nothing more. It's used
as a return path for power systems (a conductor-of-convenience).
Similar in a way, to how the metalwork in your car, forms the
second wire for DC power distribution inside the car.

And I gave a practical example. To work safely, wear short pants
with exposed leg skin. Put the desktop PC on its side on your lap.
Now, touch the inside of the ESD bag first, then pull out an item,
install. It's like your own ESD-proof lab, in miniature. You can
do a whole build that way.

Paul

Thanks Paul for the Great ESD tips, My earlier post was screwed up with
the extreme example, I somehow lost the link I was trying to include.

I'll try again.

https://www.youtube.com/watch?v=x94BH9TUiHM

hope that one hangs in there.

Rene


That looks like fun. I hope it pays well :-)

And in that movie, "every day is a sunny day".
Must be fun if there's a little weather. Sooner
or later, the boss is going to make you work, when
you shouldn't be working.

Paul

On 04/16/2018 8:38 PM, Bob_S wrote:
"Paul"Â* wrote in message news

Bob_S wrote:
"Paul"Â* wrote in message news
Bob_S wrote:
"Paul"Â* wrote in message news
Peter Jason wrote:
On Sat, 14 Apr 2018 22:25:50 -0400, Paul
wrote:

Peter Jason wrote:
My computer case is of Aluminium and earthed to a domestic copper
water pipe. , the casing of the Samsungs SSDs seem to be anodized
aluminium.Â* Since my computer case is old it has no provision
for 2.5"
SSDs I have them resting on an aluminium surface.Â*Â* Is this a
problem?
I assume the SSDs have internal insulation.
I just measured a couple SSDs here, and son of a bitch,
there's a hard connection between SSD casing and logic ground!

That's not supposed to be good for ESD handling.

I was expecting to find a 1 megohm connection between
aluminum SSD casing and the logic ground on the SSD.

But it's a hard short.

*******

The chassis of your computer case, runs at logic ground
potential.

The casing of your SSD, runs at logic ground potential.

This means you can safely rest the SSD on the bottom of
the computer case, without any "thru" current flowing.

Just don't touch a 3.3V, 5V, or 12V pin from some
Molex connector, to the chassis of the SSD. Since
it's a hard ground, we can't be carelessly resting
a Molex power pin in contact (somehow) with the chassis.

While the pins on Molex are flush or
slightly recessed, there might be some conceivable
way for something to touch. And my finding a
hard ground on the SSD chassis, is not a good
thing.

I'll be extra careful in future, to keep Molex
away from it.

I was really expecting to find a 1Megohm (high resistance)
drain between shiny aluminum SSD casing and the logic
ground next to the data pins of the SSD.

Â*Â*Â* GNDÂ*Â*Â*Â*Â*Â*Â*Â* GNDÂ*Â*Â*Â*Â*Â*Â*Â* GNDÂ*Â*Â* === logic ground pins are
longer
Â*Â*Â*Â*Â*Â*Â* tx+ tx-Â*Â*Â*Â* rx+ rx-Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* on the SSD connector.
The data
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* pins on the 7 pin data are
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* recessed. Check with the
ohmmeter,
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* between GND and chassis,
and you'll
Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â*Â* see the hard short I
measured.

Summary:

1) Safe to rest SSD on bottom of computer case, no matter
Â*Â* what the casing is made of.

2) Don't touch any "hot" Molex pins, to the SSD housing.
Â*Â* Just like you would not touch any "hot" Molex pins,
Â*Â* to the computer case metal posts. The motherboard has a hard
Â*Â* short to the chassis, through the standoffs. Most everything
Â*Â* in the computer, has a hard ground. The only poorly designed
Â*Â* feature, is "plastic fascia" on the front of the computer,
Â*Â* around front USB ports, which is a poor way to handle ESD
issues.

3) Don't scuff across the carpet and pick up your
Â*Â* SSD by the aluminum casing. Keep unused SSDs in an ESD bag,
Â*Â* scuff across the carpet if you must, pick up the
Â*Â* SSD by the ESD bag, touch the ESD bag plastic on
Â*Â* the inside of the bag, to bring yourself and the bag contents
Â*Â* to the same potential. With your other hand, touch
Â*Â* the computer chassis. Now, everything is "drained" to
Â*Â* the same electrostatic potential, you can remove the
Â*Â* SSD from the ESD bag, and connect it to SATA power
Â*Â* and SATA data.

Â*Â* By using the series resistance of the ESD bag, to limit
Â*Â* ESD current flow, you're *safely* bringing the SSD up
Â*Â* to the same electrostatic potential as the thing you
Â*Â* wish to connect it to.

Note: I just changed my handling procedure! as a result
Â*Â*Â*Â*Â* of this ohmmeter measurement. I'd assumed SSD chassis
Â*Â*Â*Â*Â* were drain connected, not "hard" connected. Now I
Â*Â*Â*Â*Â* will have to start using ESD bags for them, just as
Â*Â*Â*Â*Â* I do for hard drives.

Â*Â* Paul


Thanks Paul.Â* I have put my SSDs in plastic sleeves, and rested this
combination on cardboard.Â*Â* I thought this might be the cause of my
computer restarts.Â*Â* Also I have disabled all "fast startups" via
the
registry.

I wouldn't entirely insulate the thing. Some SSDs have
high peak power usage (SandForce compression), and they
get a little warm.

Put a cardboard underneath if you like. Leave
at least one metal surface for cooling.

In this review, you can see (and it's mentioned in the text),
that thermal pads were used on all the NAND chips. That means
both metal surfaces are used for their slight cooling advantage.

http://www.thessdreview.com/our-revi...-review-512gb/


Â*Â* Paul

Paul,

Have no idea why you would expect the SSD to be isolated from case
ground. Everything in the computer and the case itself is tied to
the grid ground. Mount a motherboard and the mounting screws screw
into the case as well as the screw heads tighten down on ground
pads on the motherboard.Â* SSD's are also grounded when placed in a
mounting tray to case ground.

As for the longer pins on power and data connectors, the pins that
are designated as ground pins are longer to insure a ground
connection is made before any data pins mate to prevent static
discharges.Â* This pin design also accommodates "hot swap" capable
devices such as hard drives and SSD's.

While it's always good practice to use measures to prevent ESD when
mounting a device such as a SSD, do not isolate it from the
mounting mechanisms such as placing an insulator between it and a
metal case. Depending on the SSD (some cases are plastic), the
metal case is the heat sink as shown in the link you included in
your post.Â* Please note that the logic board is held in-place by a
screw in the back that fastens to the SSD case and tightens against
a ground pad on the SSD logic board.

There are two ground philosophies for protecting assemblies
from ESD.

Neither was followed in this case.

Â*Â* Paul

Paul,

Not sure I follow your logic on this. The OP said he had his case
grounded to a copper pipe.Â* What wasn't stated is how his power
supply is grounded or if it was even plugged in.Â* In the US, the 3rd
lug on a plug is the green (safety) ground and in a typical home
wiring setup, the white wire and green are tied to a single bus bar
in the distribution panel so as to prevent ground loops / current loops.

So while his setup using a ground from the case to a copper water
pipe could potentially create a ground loop if there were other
wiring problems, it still is ground as long as there's no
interruption to earth ground in that copper pipe and in his wiring
and would dissipate any ESD charge.

Potential for ESD would be from him picking up the SSD and then
plugging it in before he touched the case (grounding himself) and
creating a arc between his hand holding the SSD and getting the data
or power connectors close enough so the static potential went from
him to the ground pins on the cable or the case.

That’s' why the manufactures include warnings about using ground
straps and/or touching the case before working on it.Â* What people
don't realize is that usually, they unplug the power cord from the
wall or the power supply and that’s when their case is no longer
grounded. But in the OP's situation, he had an additional ground to a
water pipe.Â* That may or may not be a good situation depending on his
house wiring and I've never seen a power supply plug without a
polarized plug.Â*Â* Now if the wall socket (old house wiring) does not
have a safety ground, then his water pipe ground is a good idea.

I've worked at radar sites and on some of the largest computer
installations in the world and worked worked with power engineers
that specialize in how "all things" need to be grounded and why.Â* It
is a complicated field of study and ESD can create havoc on computer
components when you have thousands of volts jumping between you and
the computer.

So I'm not trying to argue with you but saying "Neither was followed
in this case" didn't make sense to me.Â* Perhaps you could expand on
the "Neither" a bit.Â* I'm not sure if you are referring to the OP or
to your own situation. If it's your own, then I'll shut up and sit
down cause I don't know what or how you were doing your measurements.

1) There's no such thing as "ground". The earth is an insulated
Â*Â* ball floating in the vacuum of space. The earth is merely
Â*Â* a "reference point". It has no special properties as such.
Â*Â* "Standing on dirt is not magic." But since we are in frequent
Â*Â* contact with dirt though, it's in our best interest to not
Â*Â* touch potentials higher or lower than that potential. We could
Â*Â* get a shock.

2) To avoid ESD, bring all assemblies to "equipotential".
Â*Â* That's the trick.

If I unplug a PC from the wall, remove all cabling,
I can still *safely* install hardware in it, as long
as I follow equipotential rules. This means opening
the ESD bag but not removing the new hardware. Touch the
inside of the bag while touching the chassis. It helps
if you wear short pants and lay the metal-bodied PC flat
on your lap while working (that's if you don't own an ESD strap).

By bringing the PC, the new hardware item, and you to the
same electrostatic potential, there is no danger of ESD
damage.

And notice in that picture, there is *no* connection to
earth ground, safety ground, cold water pipes or anything.
You make an "electrostatic island" of yourself, then ensure
that all entities are "charged to the same level".

I could place my work chair on glass blocks, charge
myself to 50kV ESD level, and as long as I followed
the rules about touching the inside of the ESD bag to
bring the bag to the same potential as the other
kit, I can actually install something without damage.

The usage of ESD straps (where the ESD strap is fastened
to the case via a 10meg series resistor), is for a similar
purpose. It's not ground - it's a way to bring the
computer chassis and any other objects used in the
operation, to the same electrostatic potential. The
series resistor inside the strap, performs the same
function as the "resistive" surface inside the
ESD bag. It's a dissipative path, that limits the
ESD peak current flow level.

By placing a hard connection between the metal chassis
of the SSD and logic ground, now we have to resort
to ESD bags again, as there is no dissipative path
to logic ground. I can't really afford to scuff across
the carpet, and discharge 50kV into the SSD chassis,
because the result will now be unknown (I won't know
whether I could have damaged it or not, and it
could depend on the way the PCB and mount points are
designed). If the connection between SSD chassis
and PCB was dissipative, then I'd know there was
no possibility of a high "peak" current flow during
equalization. If the SSD chassis was plastic, I would
be using the second philosophy, which says "don't allow
static to dissipate into the item at all". Then the
advanced ground contacts take the brunt of the
equalization current flow.

And things like this aren't left to chance in the lab.
If I wanted to be sure my decision about the hard
ground on the SSD wasn't a mistake, I do this
kind of testing. We test for upset level. We
test for damage level (which is actually pretty
hard to determine, what constitutes "damage").
The bad thing about ESD, is you can "weaken" a
piece of silicon, which weeks later, decides to
completely fail. And then it's hard to trace back
exactly when you "broke it".

https://en.wikipedia.org/wiki/Human-body_model

These have changed, since the last time I tried this stuff.
We had a nasty gadget for doing up to 15kV tests on
our products. This is so much more "refined" looking.

https://transientspecialists.com/pro...contact-mode-1


There are two ways to damage things with ESD. One is
via direct discharge. The other is via "induction". When
usage of an improperly designed front USB solution blows
out the pad I/O, it's just as likely the transient
traveling down the black wire, "induces" a potential
in D+ and D-, and blows out the driver pad. When you do ESD
analysis, the danger isn't always from the direct path.

I will be switching to ESD bags from now on, for my
SSDs, and bringing myself to the same potential as the
chassis. (The same kind of gymnastics you do, when you
don't have an ESD strap handy.) It's not because I know
for a fact the SSD will fail. It's because I don't really
know, for any individual SSD, whether it has a particular
vulnerability or not. If I had a pile of these in the lab,
and an HBM-type tester, I could take a shot at finding out.

Â*Â* Paul


Paul - now you're being an ass who thinks he knows everything. Here's a
clue for you - you don't, so stop acting like it.

We come here to share knowledge - not to boost your friggin ego.



Bob_S, Better cool your irons before you start branding people. :-(

Rene

Bob_S, Better cool your irons before you start branding people. :-(

Rene

The comment was for Paul and he can certainly speak for himself.

This is for you. When someone insults by speaking down to others, I believe
they need to be called out for it.

I question how an individual can answer all questions about computer
hardware and software in such infinite detail. I find that level of
knowledge absolutely amazing. I think he is a great researcher but comes up
shy on the fix actions he's proposed.

My 40 years of experience and credentials in the telecommunications and
computer science fields, makes me question those that have all the answers
all of the time.

And no, I don't have to cool my irons.