Yellow Glue strikes again

P

Phil Allison

Guest
** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
still with us.

Most of you will have seen it holding parts down to PCBs on Asian made
equipment and many of those will have seen what happens if the parts
involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor ( M1
Active, Chinese made) ) which has blown up big time because of the damn
Yellow Glue used to secure a ferrite toroidal coil. All the glue used had
gone brown or back ( ie carbonised ) on this coil and arced across nearby
tracks taking out the main switching MOSFET, its drive IC and associated
transistors, high speed diodes and even the AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The same glue
was attacking parts elsewhere on the board too ( it corrodes copper) and had
to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs NEVER going
to wake up ??



...... Phil
 
On Wed, 31 Aug 2011 10:59:58 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
still with us.

Most of you will have seen it holding parts down to PCBs on Asian made
equipment and many of those will have seen what happens if the parts
involved get hot.
Click to expand...
Is that hot melt glue or something else?
Hot melt should, umm... melt, not burn.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
 
On 8/30/2011 8:28 PM, Jeff Liebermann wrote:
Is that hot melt glue or something else?
Hot melt should, umm... melt, not burn.
Click to expand...
No, this crap looks like 3M weather strip adhesive.
Sometimes it looks like it's applied sparingly, other times
it looks like it was put on with a caulking gun.

Jeff


--
"Everything from Crackers to Coffins"
 
"Jeffrey Angus"
No, this crap looks like 3M weather strip adhesive.
Sometimes it looks like it's applied sparingly, other times
it looks like it was put on with a caulking gun.
Click to expand...
** I've always wanted to know just WFT it really is !!

At first impression, it looks like ordinary contact adhesive - but it is
quick setting and dries to a hard surface. With time and heat it become tan
coloured and brittle. Then it goes toast brown and becomes corrosive and
conductive.

If coating the pins of an op-amp, the leakage current causes DC offsets and
crackling noises.

If coating small diodes and resistors etc - it will slowly eat the leads
right off.

If coating PCB tracks with hundreds of volts between them, the conduction
heats the glue directly until there is an explosion.

IME , a local ambient temp of about 55C is enough to set it off on its
pathway to hell.



..... Phil
 
On Wed, 31 Aug 2011 11:34:43 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

"Jeff Liebermann"

Is that hot melt glue or something else?

** So you do no repair work at all ?
Click to expand...
Just answer the question. I've seen plenty of hot melt glue being
used. It comes in clear, yellow, and brown. I've never noticed
anything else. Maybe it's a pro-audio only thing? I don't do any
pro-audio as what little audio repair work I do usually doesn't
involve incinerated parts and carbonized yellow glue.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
 
On 8/30/2011 8:50 PM, Phil Allison wrote:
** I've always wanted to know just WFT it really is !!
Click to expand...
It's probably related to that crap rubber they love to use
for drive belts and such that turns to extremely sticky goo
that's next to impossible to clean off of everything it
touches.

Jeff

--
"Everything from Crackers to Coffins"
 
On Wed, 31 Aug 2011 11:50:53 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

** I've always wanted to know just WFT it really is !!
Click to expand...
This description seems to fit:
<http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant_flame_retardant.html>
"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"

Note the photos. Is that it? I'll do some more Googling later. Gotta
seperate my customers from their money.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
 
"Jeff Liebermann"
Is that hot melt glue or something else?

** So you do no repair work at all ?

Just answer the question.
Click to expand...

** You are not a repair tech, or you would have seen it many times.

Always Asian made gear, from about the 1980s onwards.

TV sets, VCRs, SMPSs anything where the maker felt it was a good idea to
glue things to the PCB.

Do a Google search on this NG under " yellow glue".



...... Phil
 
On Tue, 30 Aug 2011 18:56:39 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Wed, 31 Aug 2011 11:50:53 +1000, "Phil Allison" <phil_a@tpg.com.au
wrote:

** I've always wanted to know just WFT it really is !!

This description seems to fit:
http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant_flame_retardant.html
"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"

Note the photos. Is that it? I'll do some more Googling later. Gotta
seperate my customers from their money.
Click to expand...
More:
<http://www.aliexpress.com/store/906248/210638773-439369255/accept-sample-order-wholesale-flame-retardant-yellow-adhesive-free-shipping-for-you.html>
The page says it's an "acrylic".

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
 
On 8/30/2011 8:56 PM, Jeff Liebermann wrote:
"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"
Click to expand...
Odd, I read this: "Usage: Construction, Fiber & Garment, Footwear "

Jeff, but yeah, that sure looks like it.
Some of the stuff looks almost porous.

Jeff

--
"Everything from Crackers to Coffins"
 
"Jeff Liebermann"
** I've always wanted to know just WFT it really is !!

This description seems to fit:

http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant_flame_retardant.html

"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"

Note the photos. Is that it?
Click to expand...

** Sure as heck looks like the vile stuff.

But the stuff has been in use for decades, firstly with Taiwanese made gear.

The specs quoted do not mention aging or the effects of temperature - so the
marketing is dishonest.

BTW:

the pics show the glue in its liquid state, when dry the surface is quite
dull.

To me, the pics are cringe worthy.

Like looking at pics of child abuse.



..... Phil
 
On Tue, 30 Aug 2011 21:04:46 -0500, Jeffrey Angus <grendelair@aim.com>
wrote:

On 8/30/2011 8:56 PM, Jeff Liebermann wrote:
"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"

Odd, I read this: "Usage: Construction, Fiber & Garment, Footwear "
Click to expand...
Sure. Haven't you seen PCB shoes and underwear?
<http://blogs.discovermagazine.com/discoblog/2010/04/07/circuit-board-chic-motherboards-recycled-into-shoes-and-boxers/>
<http://boingboing.net/2010/04/06/circuit-board-shoes.html>
<http://www.zazzle.com/circuit_board_shoes-167287736986690214>
<http://www.xactstudios.com/pcbcreations/>
<http://www.zazzle.com/computer_circuit_board_shoes-167535214684590497>
<https://plus.google.com/103033413691031223989/posts/Kq6qgFDULaj>

Jeff, but yeah, that sure looks like it.
Some of the stuff looks almost porous.
Click to expand...
Agressive hardener action causing gas bubbles. It's acrylic, but I'm
not familiar with the chemistry. I'll dig it out, later...

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
 
"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:9c5fb1FhtrU1@mid.individual.net...
** I had hoped that the dreaded Yellow Glue peril had gone away - but it
is still with us.

Most of you will have seen it holding parts down to PCBs on Asian made
equipment and many of those will have seen what happens if the parts
involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor ( M1
Active, Chinese made) ) which has blown up big time because of the damn
Yellow Glue used to secure a ferrite toroidal coil. All the glue used had
gone brown or back ( ie carbonised ) on this coil and arced across nearby
tracks taking out the main switching MOSFET, its drive IC and associated
transistors, high speed diodes and even the AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The same
glue was attacking parts elsewhere on the board too ( it corrodes copper)
and had to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs NEVER
going to wake up ??



..... Phil
Click to expand...

I had an M1 with exactly the same problem. Conductive gak all over the
place, very messy, but fortunately didn't blow anything up.



Gareth.
 
Jeff Liebermann <jeffl@cruzio.com> wrote in message
news:835r57pbgh3vv5jcj855s221u912u1fu0c@4ax.com...
On Wed, 31 Aug 2011 11:50:53 +1000, "Phil Allison" <phil_a@tpg.com.au
wrote:

** I've always wanted to know just WFT it really is !!

This description seems to fit:

http://www.alibaba.com/product-gs/482344777/One_component_solvent_resistant
Click to expand...
_flame_retardant.html>
"One component solvent resistant flame-retardant waterproof yellow
fixing adhesive glue for electronic components"

Note the photos. Is that it? I'll do some more Googling later. Gotta
seperate my customers from their money.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS
Click to expand...


That "Japanese" brown gloop made a comeback also, from my trepair briefs

Sherwood RD6106 tuner amp, may 2000 from front panel moulding
I though that hygroscopic brown glue stuff went out in the 70s. Used to
secure 12.288M crystal for the digital interface processor YSS912C-F , was
around its
pin and had rusted through at the epoxy bond.
 
If the brown hard-glue is the same as the yellow stuff. Is the progress to
destruction that it becomes hygroscopic going from yellow to brown and so
becomes conductive for CMOSSy sort of stuff but if HV around then conducts
enough to then carbonise and become ever more conductive?
 
On Wed, 31 Aug 2011 10:59:58 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
still with us.

Most of you will have seen it holding parts down to PCBs on Asian made
equipment and many of those will have seen what happens if the parts
involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor ( M1
Active, Chinese made) ) which has blown up big time because of the damn
Yellow Glue used to secure a ferrite toroidal coil. All the glue used had
gone brown or back ( ie carbonised ) on this coil and arced across nearby
tracks taking out the main switching MOSFET, its drive IC and associated
transistors, high speed diodes and even the AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The same glue
was attacking parts elsewhere on the board too ( it corrodes copper) and had
to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs NEVER going
to wake up ??



..... Phil
Click to expand...

The rumor among techs in the U.S. when this stuff first showed up was
it was originally manufactured by Sony and it was known as "Sony
glue". Don't know if there was any truth to this or not. As Phil
said, it was in widespread use, for example: Mitsubishi televisions,
Adcom preamps and tuners, Yamaha receivers, Extron products and many
others which I can't recall off the top of my head. Chuck
 
Phil Allison <phil_a@tpg.com.au> wrote:
"Jeff Liebermann"

Is that hot melt glue or something else?

** So you do no repair work at all ?

Just answer the question.


** You are not a repair tech, or you would have seen it many times.

Always Asian made gear, from about the 1980s onwards.

TV sets, VCRs, SMPSs anything where the maker felt it was a good idea to
glue things to the PCB.

Do a Google search on this NG under " yellow glue".
Click to expand...
that stuff is pure shit.
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:j3kvss$l47$1@dont-email.me...
If the brown hard-glue is the same as the yellow stuff. Is the progress to
destruction that it becomes hygroscopic going from yellow to brown and so
becomes conductive for CMOSSy sort of stuff but if HV around then conducts
enough to then carbonise and become ever more conductive?
Click to expand...
The brown brittle stuff I scraped off the M1 PCB was around the low voltage
audio pre-amp and Power Amp IC.
It was conductive enough to render the circuit useless, no HV necessary.



Gareth.
 
"Gareth Magennis" <sound.service@btconnect.com> wrote in
news:Ixl7q.182412$2I6.127551@newsfe27.ams2:

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:9c5fb1FhtrU1@mid.individual.net...

** I had hoped that the dreaded Yellow Glue peril had gone away - but
it is still with us.

Most of you will have seen it holding parts down to PCBs on Asian
made equipment and many of those will have seen what happens if the
parts involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor (
M1 Active, Chinese made) ) which has blown up big time because of the
damn Yellow Glue used to secure a ferrite toroidal coil. All the
glue used had gone brown or back ( ie carbonised ) on this coil and
arced across nearby tracks taking out the main switching MOSFET, its
drive IC and associated transistors, high speed diodes and even the
AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The
same glue was attacking parts elsewhere on the board too ( it
corrodes copper) and had to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs NEVER
going to wake up ??



..... Phil
Click to expand...
the manufacturers probably don't get the products back(due to their age)
for failure analysis,and thus are unaware it happens.
No "closed-loop action process".

OR,it's planned "obsolesence".
or both. ;-)
I had an M1 with exactly the same problem. Conductive gak all over
the place, very messy, but fortunately didn't blow anything up.



Gareth.
Click to expand...


--
Jim Yanik
jyanik
at
localnet
dot com
 
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