USB stick leaking

VanguardLH wrote:
Linea Recta wrote:

"VanguardLH" schreef in bericht
...
Linea Recta wrote:

"Linea Recta" ...

I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
The stick looks like this one:

https://www.amazon.com/Lexar-JumpDri.../dp/B0021AFWL4

but I took a magnifying glass to read what's exactly on mine:

lexar LJDTT4GB-000-1001AC
333074GBGA
N12610

product of China
http://www.lexar.com/products/usb-fl...ash-Drive.html

Those are not listed as waterproof/resistant so there should be no
silicone filling to ooze out (but shouldn't anyway since, when it set,
silicone is not going to ooze but burn from an overheated chip).

Is what oozed out soft or hard? Is it like paste that you can smoosh
between your fingers, like toothpaste? Is it rubbery, like silicone
caulking? It is hard, like the plastic shell itself?
It is sticky and quite soft. Colour: transparent yellowish.
I tried to clean it, but it seems the red colour of the case comes off
now...
BTW I'm not aware the stick ran hot.

"transparent yellowish" had me first think it was solder rosin (aka
resin aka flux); however, the chips, connector, and other components are
wave soldered onto the PCB. If rosin were oozing out

Well, maybe. Some of the USB flash sticks are double sided, and would
use double-IR reflow, with water soluble flux (used with the new solders).
The flux is washed off after the soldering steps. (Gone are the days when
the washing machine was filled with trike, and the fluid was filthy and
left a film.) I worked early enough in the industry, to receive boards
that were improperly washed with the old solvent.

I worked early enough, to see our own blank PCB manufacturing facility.
With tanks of vile dark fluids (etchant and plate-up), the press for
laminating the boards, and so on. Later, all that work was farmed out,
and the PCB plant removed. The plant for that was poorly lit, and it
looked like a medieval torture chamber of some sort.

*******

The USB connector would be a different matter, as some of those
are thru-hole. So the entire manufacturing process may require
three steps. With the USB keys done in large sheets, and sawed
up afterwards. You could not run a item like that through a
standard manufacturing line, because it's too small. The boards
usually have a keepout zone on the edges, so the board can ride on
rails as it goes through the IR oven. I'm not aware of the
details of how they're sawed and milled later. At one time,
a cruder technique (tiny boards snapped off along a perforation
line) was the technique of the day. But professionally prepared
product today seems to be milled on all edges. I didn't see
any kind of milling, sawing, or cleaving equipment at my work.

I didn't live at the factory, and only got to visit. We didn't
have a "tightly integrated" manufacturing organization, so I
was spared frequent, long drives, to the factory. One other
company in town, the "factory" is only a hundred feet from
your desk. And you'd never get a moments peace.

*******

I can't think of a material that's a good match for "transparent yellowish"
and belongs on an electronics board. And is chemically strong
enough to remove a finish on the chassis. Normally, any chemicals
are precisely applied, and the curing steps are finished well
before the product leaves the factory.

If BGA chips are used on the PCB, the ball count is low enough
that "underfill" is not required. The material that is used
for underfill, may fit that description. Underfill is used
on things like GPUs or maybe a Northbridge or Southbridge.
Maybe around 1500 balls or so, could use some underfill,
especially if diurnal temperature variation has a wide
enough swing (GPUs that get burning hot). Underfill is used
for stress relief, so the solder balls don't crack or shear off.

If you want to learn more about underfill materials, most have
patents, so you can track down the chemistry that way.

Paul

On 04/20/2017 10:30 AM, Wolf K wrote:
On 2017-04-20 13:13, Linea Recta wrote:
I used a Lexar USB stick yesterday to boot a computer. I haven't used the
stick intensively, but now I noticed that it is leaking sticky stuff from
the seam on the sides. Any idea what the stuff is? Is it toxic? Can I
keep
using the stick normally?

Probably glue, reacting with the plastic's filler. Or filler itself.
Filler is used to control hardness, colour, flexibility, etc. In cheap
plastics, it will react with air (oxygen), water, etc.

I'd copy everything off it, maybe try to fix it, more likely trash it.
Lexar is a good brand, I wonder if you purchased a fake.


1+

Kanguru and Kingston are also good brands

[]
"Linea Recta" schreef in bericht
news I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
[]
An AMAZING amount of analysis from everybody!

Since nobody seems to think it _really_ is coming out (or at least
no-one can think of anything there'd be enough of to be oozing as
described), could it be that you - or someone in your household - has
dropped it in something, or dropped something on it (possibly from
something leaking above it), such that it just _looks_ as if it's coming
out?

[Does it smell or taste funny/good/bad? No responsibility taken if you
try, mind (-:!]
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Sometimes you win, sometimes you learn.

J. P. Gilliver (John) wrote:
[]
"Linea Recta" schreef in bericht
news I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
[]
An AMAZING amount of analysis from everybody!

Since nobody seems to think it _really_ is coming out (or at least
no-one can think of anything there'd be enough of to be oozing as
described), could it be that you - or someone in your household - has
dropped it in something, or dropped something on it (possibly from
something leaking above it), such that it just _looks_ as if it's coming
out?

[Does it smell or taste funny/good/bad? No responsibility taken if you
try, mind (-:!]

We were taught in chem class, not to do that :-) Naughty.

And the reason for the warning, is early chemists did this,
and some died of cancer. And the cancer type, correlated with
the sampling method (cancer of the tongue, mouth, etc).

Even the scientists who worked on radioactive elements,
had the misfortune to succumb to the stuff they were
working on.

Learning is hard.

Hindsight is perfect.

*******

I would think, if the compound had a smell, if would have
been mentioned by now :-)

When I took chem, one of the things you have to do, is you're
given an unknown organic compound, and you have to identify it.
You spend an entire term, one lab a week, trying various
instrumentation methods on it.

Now, being a clever noob, I immediately did a melting point
determination on mine. That reduced the set of possible compounds
to around 200 of them or so. (Using the CRC Chem tables which
are sorted by melting point.) And it's a good thing I did that
right away. Because soon after, the compound started to break
down on its own. And the byproducts smelled like... ****. Every
time I had to open the sample bottle, to get a little bit of
the stuff to place in some test instrument (NRM, Mass Spec, CHN),
I had to put up with that stink. No, we don't go out of our way
to sniff stuff like that :-) I'm sure the staff member in the
chem department who selected that compound, knew what they were
doing. Every student was given a unique compound, so you could
not compare notes and cheat. And the compounds seemed to be
pure when we received them. You grabbed a numbered sample bottle,
and off you went. And no, none of the compounds were "easy"
like something from this page.

http://www.chm.bris.ac.uk/motm/ethylacetate/smells.htm

During open house at the university chem lab, one lab
used to synthesize some of those for... sniffing :-)

Probably by the time you've taken high school chem,
you've made something from that web page. Maybe
methyl salicylate ? That one is pretty easy.

Paul

In message , Paul
writes:
J. P. Gilliver (John) wrote:
[]
"Linea Recta" schreef in bericht
news I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
[]
An AMAZING amount of analysis from everybody!
Since nobody seems to think it _really_ is coming out (or at least
no-one can think of anything there'd be enough of to be oozing as
described), could it be that you - or someone in your household - has
dropped it in something, or dropped something on it (possibly from
something leaking above it), such that it just _looks_ as if it's coming out?
[Does it smell or taste funny/good/bad? No responsibility taken if
you try, mind (-:!]

We were taught in chem class, not to do that :-) Naughty.

Hence my final few words!

So far (I'm nearly 57) I've survived having such an enquiring mind ...

And the reason for the warning, is early chemists did this,
and some died of cancer. And the cancer type, correlated with
the sampling method (cancer of the tongue, mouth, etc).

Certainly, those who made luminous instruments (for aircraft for use in
the dark, certain wris****ches, etc.), which used to be made with
radium-laden paint, suffered because they tended to lick their
paintbrushes to get a good point on them ...
[]
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

After I'm dead I'd rather have people ask why I have no monument than why I
have one. -Cato the Elder, statesman, soldier, and writer (234-149 BCE)

On 04/22/2017 10:35 AM, J. P. Gilliver (John) wrote:

I used a Lexar USB stick yesterday to boot a computer. I haven't
used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
[]
An AMAZING amount of analysis from everybody!
Since nobody seems to think it _really_ is coming out (or at least
no-one can think of anything there'd be enough of to be oozing as
described), could it be that you - or someone in your household - has
dropped it in something, or dropped something on it (possibly from
something leaking above it), such that it just _looks_ as if it's
coming out?
[Does it smell or taste funny/good/bad? No responsibility taken if
you try, mind (-:!]

We were taught in chem class, not to do that :-) Naughty.

Hence my final few words!

So far (I'm nearly 57) I've survived having such an enquiring mind ...

And the reason for the warning, is early chemists did this,
and some died of cancer. And the cancer type, correlated with
the sampling method (cancer of the tongue, mouth, etc).

Certainly, those who made luminous instruments (for aircraft for use in
the dark, certain wris****ches, etc.), which used to be made with
radium-laden paint, suffered because they tended to lick their
paintbrushes to get a good point on them ...

I just heard an interview with the author of a book about those young
women, the radium painters. The author claims that they were *told to*
lick their paintbrushes.

Perce

On 04/21/2017 07:09 PM, T wrote:

I used a Lexar USB stick yesterday to boot a computer. I haven't used
the
stick intensively, but now I noticed that it is leaking sticky stuff
from
the seam on the sides. Any idea what the stuff is? Is it toxic? Can I
keep
using the stick normally?

Probably glue, reacting with the plastic's filler. Or filler itself.
Filler is used to control hardness, colour, flexibility, etc. In cheap
plastics, it will react with air (oxygen), water, etc.

I'd copy everything off it, maybe try to fix it, more likely trash it.
Lexar is a good brand, I wonder if you purchased a fake.


1+

Kanguru and Kingston are also good brands

For a long time I bought Kingston RAM almost exclusively. Then a few
days after I bought the RAM that they recommended for my motherboard,
they took it off their recommended list, and just a few days later again
discontinued its production. Then there are the reports of Kingston
having submitted SSD samples for testing, then shipping out modules with
the same Model# but with inferior and slower components.

Perce

"J. P. Gilliver (John)" wrote in message
...
[]
"Linea Recta" schreef in bericht
news I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
[]
An AMAZING amount of analysis from everybody!

Since nobody seems to think it _really_ is coming out (or at least no-one
can think of anything there'd be enough of to be oozing as described),
could it be that you - or someone in your household - has dropped it in
something, or dropped something on it (possibly from something leaking
above it), such that it just _looks_ as if it's coming out?

Is it data leaking out of the drive? Has the "sticky bit" been set? :-)

VanguardLH wrote:
Linea Recta wrote:

"VanguardLH" schreef in bericht
...
Linea Recta wrote:

"Linea Recta" ...

I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
The stick looks like this one:

https://www.amazon.com/Lexar-JumpDri.../dp/B0021AFWL4

but I took a magnifying glass to read what's exactly on mine:

lexar LJDTT4GB-000-1001AC
333074GBGA
N12610

product of China
http://www.lexar.com/products/usb-fl...ash-Drive.html

Those are not listed as waterproof/resistant so there should be no
silicone filling to ooze out (but shouldn't anyway since, when it set,
silicone is not going to ooze but burn from an overheated chip).

Is what oozed out soft or hard? Is it like paste that you can smoosh
between your fingers, like toothpaste? Is it rubbery, like silicone
caulking? It is hard, like the plastic shell itself?
It is sticky and quite soft. Colour: transparent yellowish.
I tried to clean it, but it seems the red colour of the case comes off
now...
BTW I'm not aware the stick ran hot.

"transparent yellowish" had me first think it was solder rosin (aka
resin aka flux); however, the chips, connector, and other components are
wave soldered onto the PCB. If rosin were oozing out, I'd suspect
someone refurbished the device by, for example, replacing the memory
chip and they had to use a rework station that employed rosin to assist
in removing the chip, dewicking the solder off the chip, and later when
soldering the new chip onto the pads on the PCB. When using rosin, and
in a rework lab, there is usually a bath where the parts are dipped or
sprayed to remove the excess rosin. Another possibility is excessive
application of rosin during original manufacturer.

https://www.youtube.com/watch?v=CalydGKwEy8

That shows a guy removing a memory chip and noticed there was excessive
rosin left behind. Rosin doesn't flow at room temperature. That's why
it stays in the core of solder thread that incorporates solder inside of
it. It does flow when heated. Just because it doesn't feel hot to you
does not mean the chip(s) was not hot. All USB flash drives generate
heat. A plastic case has a slower transfer rate than metal. That means
a plastic cased USB flash drive will dissipate heat more slowly and it
also means you won't feel as much heat. A metal cased drive will feel
hotter to the touch than with the same PCB and components on it inside
of a plastic case.

The shell is typically 2 halves made of plastic that are snapped
together. Maybe the soft stuff was a sealant. I'm guessing rosin.
Original manufacture would leave almost no rosin behind. Little, if
any, would be used during original manufacture and if any were used then
the PCB goes through a bath to remove the rosin. Maybe you got a
remanufactured device. Refurbished usually means just testing and
passing the device on if testing is successful. Most times, refurbish
has nothing physically done to the device. Remanufacture means
rebuilding some of it.

I don't have any of those so I cannot pop one apart to look inside.
Haven't found a Youtube video about USB drive disassembly that looks at
that specific brand and model. The above video is for a Lexar JumpDrive
but a different model. The video author noticed excess rosin on the
memory chip at timemark 5:50. He uses a hot air desoldering station
which does not apply any flux. What he noted on the memory chip was
already there. The flux was on the underside of the chip (between chip
and PCB). So the manufacture process used flux (rosin) but did not do a
good job at washing it off. It is a tight fit between chip and board
but the flux was all over the bottomside of the chip. Seems Lexar's
manufacture process is sloppy with rosin since it only needs to be
applied for soldering the pins on the chip and nowhere as much on the
pins as what is shown sticking to the bottomside of this chip in this
video. Sloppy manufacture.

There is a video here from a Kingston USB flash plant.

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

What impresses me most, is the degree of robotic handling.

All except the last step, where sticky labels are being
applied by hand! A win for humans.

So maybe the yellow substance, is grease that fell off one
of the machines :-\

In the video, you can see the milling machine that scribes
the product into individual flash drives. It's a kind of
plunge router.

I expected all the handling after scribing, to be done by humans,
but nope, a win for the robots instead. The humans just
stand around and give interviews.

Paul

On 4/22/2017 5:18 PM, Paul wrote:
VanguardLH wrote:
Linea Recta wrote:

"VanguardLH" schreef in bericht
...
Linea Recta wrote:

"Linea Recta" ...

I used a Lexar USB stick yesterday to boot a computer. I haven't used
the stick intensively, but now I noticed that it is leaking sticky
stuff from the seam on the sides. Any idea what the stuff is? Is it
toxic? Can I keep using the stick normally?
The stick looks like this one:

https://www.amazon.com/Lexar-JumpDri.../dp/B0021AFWL4


but I took a magnifying glass to read what's exactly on mine:

lexar LJDTT4GB-000-1001AC
333074GBGA
N12610

product of China
http://www.lexar.com/products/usb-fl...ash-Drive.html


Those are not listed as waterproof/resistant so there should be no
silicone filling to ooze out (but shouldn't anyway since, when it set,
silicone is not going to ooze but burn from an overheated chip).

Is what oozed out soft or hard? Is it like paste that you can smoosh
between your fingers, like toothpaste? Is it rubbery, like silicone
caulking? It is hard, like the plastic shell itself?
It is sticky and quite soft. Colour: transparent yellowish.
I tried to clean it, but it seems the red colour of the case comes
off now...
BTW I'm not aware the stick ran hot.

"transparent yellowish" had me first think it was solder rosin (aka
resin aka flux); however, the chips, connector, and other components are
wave soldered onto the PCB. If rosin were oozing out, I'd suspect
someone refurbished the device by, for example, replacing the memory
chip and they had to use a rework station that employed rosin to assist
in removing the chip, dewicking the solder off the chip, and later when
soldering the new chip onto the pads on the PCB. When using rosin, and
in a rework lab, there is usually a bath where the parts are dipped or
sprayed to remove the excess rosin. Another possibility is excessive
application of rosin during original manufacturer.

https://www.youtube.com/watch?v=CalydGKwEy8

That shows a guy removing a memory chip and noticed there was excessive
rosin left behind. Rosin doesn't flow at room temperature. That's why
it stays in the core of solder thread that incorporates solder inside of
it. It does flow when heated. Just because it doesn't feel hot to you
does not mean the chip(s) was not hot. All USB flash drives generate
heat. A plastic case has a slower transfer rate than metal. That means
a plastic cased USB flash drive will dissipate heat more slowly and it
also means you won't feel as much heat. A metal cased drive will feel
hotter to the touch than with the same PCB and components on it inside
of a plastic case.

The shell is typically 2 halves made of plastic that are snapped
together. Maybe the soft stuff was a sealant. I'm guessing rosin.
Original manufacture would leave almost no rosin behind. Little, if
any, would be used during original manufacture and if any were used then
the PCB goes through a bath to remove the rosin. Maybe you got a
remanufactured device. Refurbished usually means just testing and
passing the device on if testing is successful. Most times, refurbish
has nothing physically done to the device. Remanufacture means
rebuilding some of it.

I don't have any of those so I cannot pop one apart to look inside.
Haven't found a Youtube video about USB drive disassembly that looks at
that specific brand and model. The above video is for a Lexar JumpDrive
but a different model. The video author noticed excess rosin on the
memory chip at timemark 5:50. He uses a hot air desoldering station
which does not apply any flux. What he noted on the memory chip was
already there. The flux was on the underside of the chip (between chip
and PCB). So the manufacture process used flux (rosin) but did not do a
good job at washing it off. It is a tight fit between chip and board
but the flux was all over the bottomside of the chip. Seems Lexar's
manufacture process is sloppy with rosin since it only needs to be
applied for soldering the pins on the chip and nowhere as much on the
pins as what is shown sticking to the bottomside of this chip in this
video. Sloppy manufacture.

There is a video here from a Kingston USB flash plant.

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

What impresses me most, is the degree of robotic handling.

All except the last step, where sticky labels are being
applied by hand! A win for humans.

So maybe the yellow substance, is grease that fell off one
of the machines :-\

In the video, you can see the milling machine that scribes
the product into individual flash drives. It's a kind of
plunge router.

I expected all the handling after scribing, to be done by humans,
but nope, a win for the robots instead. The humans just
stand around and give interviews.

Paul


The complexity of these robotic machines is amazing, Designing and
building these machines must be an art in itself.

Rene