coming unglued

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I just wanted to pass this on, maybe save someone
else similar trouble with respect to using
HOT GLUE to hold components and loose wires to
circuit boards. In short: don't.

I wanted to improve the mechanical strength of
wires and some standing components on a board so
I thought hot glue would do the job.
After testing good for function, I glued the board up
only to find later many malfunctions, ignored
inputs, missing outputs, and sporatic resets
(on an atmel avr design using SSOP chips if that matters).
Yes, I glued over traces
on the copper side... but I did test the glue for
resistive value (too high for my meter) so I
thought I was safe. I had to pick the glue off from
around wires and devices and lo and behold things
worked better again. This was run-of-the-mill dollar
store hot glue sticks.

OK.. my guess is glue was acting as a dialectric and I
had "created capacitors" between I/O pins and
power lines and reset.. that caused erratic charges
to jump about creating havoc. I can't think of what
else it could be. Of course, this is probably documented
in some FAQ of do's and dont's.. anybody got a
pointer to that FAQ ;-)

Regards,
Scott

Regards,
Scott

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I don't think your problem is the glue. The change in dialectric contant from air is not going to be so great to cause so drastic changes in your circuit.

However by glueing wires together or to the PCB you may be experiencing crosstalk due to the close proximity of the wires. (you should almways try to avoid signal with fast edges traveling off board).
Alternatively you may have some dry solder joints that thave been disturned by the expantion and contaction of the glue as it dries.

Incidently I once used double-sided sticky pad on a pcb and years later found that the adhiesive had disolved the copper tracks!

Colin

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Hi,

in wire production adhesives are well known for increasing the attenuation dramatically.
( I could ask for the reason if someone is interested ... )
The glue should be full of it.
And the dielectric constant is somewhat of 2.3 So i.m.h.o. this might very well have an influence.

You could possibly try a two-component-resin. Though that is very hard to remove..

good luck

Klaus

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