That awful yellow glue on circuit boards...

[James Jones]

Why are manufacturers still using that crappy yellow glue on circuit
boards? You often see it securing large components such as
electrolytics, board mounted transformers, and coils. When the glue
turns from yellow to brown it becomes conductive. I don't know if heat
or current or the combination of both cause it to change, but I've had
computer monitors and VCR's malfunction because of it.

My latest experience is with a set of computer speakers--Boston
Acoustics BA735. When I got them the volume was very low and there was a
fairly loud 60hz hum coming from the subwoofer. The amplifier pc board
inside the subwoofer has all the jacks mounted on one edge--power, din
socket for the satellites, digital in, analog in, and a bass level pot.
All these jacks had a liberal amount of this yellow glue poured between
and behind them. Unfortunately this stuff was covering many surface
mounted devices as well as a couple of electrolytics. Parts of it had
turned dark brown and brittle. I scraped a lot of it using a serrated
plastic knife (McDonald's) and carefully pryed away smaller bits using a
dental pick. I had to desolder the din socket, digital in jack and caps
to get some of it. After putting it all back together, the speakers
sound perfect!

I guess the only reason the manufacturers still use this glue is because
it's dirt cheap. They don't seem to care that it will cause the device
to malfunction 5 years down the road. Silicon RTV would work so much better.

 

[Ken Weitzel]

Why are manufacturers still using that crappy yellow glue on circuit
boards? You often see it securing large components such as
electrolytics, board mounted transformers, and coils. When the glue
turns from yellow to brown it becomes conductive. I don't know if heat
or current or the combination of both cause it to change, but I've had
computer monitors and VCR's malfunction because of it.

My latest experience is with a set of computer speakers--Boston
Acoustics BA735. When I got them the volume was very low and there was a
fairly loud 60hz hum coming from the subwoofer. The amplifier pc board
inside the subwoofer has all the jacks mounted on one edge--power, din
socket for the satellites, digital in, analog in, and a bass level pot.
All these jacks had a liberal amount of this yellow glue poured between
and behind them. Unfortunately this stuff was covering many surface
mounted devices as well as a couple of electrolytics. Parts of it had
turned dark brown and brittle. I scraped a lot of it using a serrated
plastic knife (McDonald's) and carefully pryed away smaller bits using a
dental pick. I had to desolder the din socket, digital in jack and caps
to get some of it. After putting it all back together, the speakers
sound perfect!

I guess the only reason the manufacturers still use this glue is because
it's dirt cheap. They don't seem to care that it will cause the device
to malfunction 5 years down the road. Silicon RTV would work so much
better.

Hi...

I suspect that they _do_ care that it's going to contribute to premature
failure.

Ken

 

[JANA]

The low cost consumer electronics is designed for a 2 to 3 year lifespan.
The glue they use is a low cost fast drying adhesive that assists in holding
the components in place during the automated soldering procedure. If they
didn't use this type of glue, the cost of the end product would be higher.

Your solution is to buy better quality electronic equipment, where there is
more hand assembly, and where they use more expensive procedures to do the
assembly.

--

JANA
_____


Why are manufacturers still using that crappy yellow glue on circuit
boards? You often see it securing large components such as
electrolytics, board mounted transformers, and coils. When the glue
turns from yellow to brown it becomes conductive. I don't know if heat
or current or the combination of both cause it to change, but I've had
computer monitors and VCR's malfunction because of it.

My latest experience is with a set of computer speakers--Boston
Acoustics BA735. When I got them the volume was very low and there was a
fairly loud 60hz hum coming from the subwoofer. The amplifier pc board
inside the subwoofer has all the jacks mounted on one edge--power, din
socket for the satellites, digital in, analog in, and a bass level pot.
All these jacks had a liberal amount of this yellow glue poured between
and behind them. Unfortunately this stuff was covering many surface
mounted devices as well as a couple of electrolytics. Parts of it had
turned dark brown and brittle. I scraped a lot of it using a serrated
plastic knife (McDonald's) and carefully pryed away smaller bits using a
dental pick. I had to desolder the din socket, digital in jack and caps
to get some of it. After putting it all back together, the speakers
sound perfect!

I guess the only reason the manufacturers still use this glue is because
it's dirt cheap. They don't seem to care that it will cause the device
to malfunction 5 years down the road. Silicon RTV would work so much better.

 

[Sam Goldwasser]

The low cost consumer electronics is designed for a 2 to 3 year lifespan.
The glue they use is a low cost fast drying adhesive that assists in holding
the components in place during the automated soldering procedure. If they
didn't use this type of glue, the cost of the end product would be higher.

Your solution is to buy better quality electronic equipment, where there is
more hand assembly, and where they use more expensive procedures to do the
assembly.

--

JANA
_____


Why are manufacturers still using that crappy yellow glue on circuit
boards? You often see it securing large components such as
electrolytics, board mounted transformers, and coils. When the glue
turns from yellow to brown it becomes conductive. I don't know if heat
or current or the combination of both cause it to change, but I've had
computer monitors and VCR's malfunction because of it.

My latest experience is with a set of computer speakers--Boston
Acoustics BA735. When I got them the volume was very low and there was a
fairly loud 60hz hum coming from the subwoofer. The amplifier pc board
inside the subwoofer has all the jacks mounted on one edge--power, din
socket for the satellites, digital in, analog in, and a bass level pot.
All these jacks had a liberal amount of this yellow glue poured between
and behind them. Unfortunately this stuff was covering many surface
mounted devices as well as a couple of electrolytics. Parts of it had
turned dark brown and brittle. I scraped a lot of it using a serrated
plastic knife (McDonald's) and carefully pryed away smaller bits using a
dental pick. I had to desolder the din socket, digital in jack and caps
to get some of it. After putting it all back together, the speakers
sound perfect!

I guess the only reason the manufacturers still use this glue is because
it's dirt cheap. They don't seem to care that it will cause the device
to malfunction 5 years down the road. Silicon RTV would work so much better.

I've seen it in the past on top-of-the-line equipment. I doubt they
use it to provide timed decay. Manufacturing is probably just not aware
of the effects 10 years down the line.

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[Dave D]

I've seen it in the past on top-of-the-line equipment.

So have I, notably on expensive, portable, two way radio equipment.

Dave

 

[Bob Parker]

The stuff is also humidity-sensitive. The first time I ever
encountered it was in a car radio which broke into audio oscillation
in wet weather.
I've seen it cause electrolysis between PCB tracks with a
significant DC voltage difference, actually corroding right through
them. And that was despite the fact that there was a layer of green
solder resist between the tracks and the glue!
You'd think that equipment manufacturers would have been fully
aware years ago, of what that dreadful glue does as it ages. The fact
that they still persist in using it implies that they know it's going
to cause equipment failures a few years down the track.

Bob

 

[Dave D]

The stuff is also humidity-sensitive. The first time I ever
encountered it was in a car radio which broke into audio oscillation
in wet weather.
I've seen it cause electrolysis between PCB tracks with a
significant DC voltage difference, actually corroding right through
them. And that was despite the fact that there was a layer of green
solder resist between the tracks and the glue!
You'd think that equipment manufacturers would have been fully
aware years ago, of what that dreadful glue does as it ages. The fact
that they still persist in using it implies that they know it's going
to cause equipment failures a few years down the track.

I wonder if hot melt adhesive is a viable alternative? That's what I use
when I have to replace that awful glue and it has yet to come back to bite
me- it seems fairly neutral.

Dave

 

[Jason D.]

I wonder if hot melt adhesive is a viable alternative? That's what I use
when I have to replace that awful glue and it has yet to come back to bite
me- it seems fairly neutral.

Dave

Till late 2003, RCA was using hot glue to secure heavy parts and got
bitten back because the heat and vibration (even 15.7KHz will) made
hot melt glue slide through the lead and the solder breaking the
solder bond.

Was used from before CTC169 all the way to few ATC113 then RCA
smartened up and quit using it.

Sneaky.

Only, and only two ways: Do nothing with glue anything using good
design practices or use silicone glue.

Cheers, Wizard

 

[Ray]

Why are manufacturers still using that crappy yellow glue on circuit

boards? You often see it securing large components such as
electrolytics, board mounted transformers, and coils. When the glue
turns from yellow to brown it becomes conductive. I don't know if heat
or current or the combination of both cause it to change, but I've had
computer monitors and VCR's malfunction because of it.

<snip experiences we've all seen before, unfortunately>

Heat degrades the glue and it then becomes hygroscopic, absorbs moisture
out of the air. It's then conductive and corrosive. That glue has been around a
-long- time... more than long enough for manufacturers to know better. You can't
get it off until it starts discoloring. I've tried. I first saw the effects on
tube color TV yokes. Older techs will remember the brown stuff that when peeled
away revealed green corrosion and open (vertical) or burned (horizontal) coils.
I've seen old JVC and Mitsubishi VCRs with whole boards covered with glue. It's
like a Stephen King horror story.

Ray