Russell McMahon wrote:

> Hot melt is a bad choice for most things, ultimately. Its quick and
> easy to use and sets quite quickly but it doesn't last as a glue.
> Many people use it in electronic assemblies and my universal
> experience is that it deteriorates in a year or two. If the glue is
> load bearing the glued object drops off and does whatever the glue
> was initially meant to stop it doing. (Its excellent for use in
> products with a one year warranty :-)).
>
> A much nicer adhesive which lasts longer than I have been using it
> (the manufacturer of some versions says it will last 20 years out in
> the weather) is "Silicon Rubber" (RTV etc). This sets in hours rather
> than minutes but doesn't let go. Messier, gap filling and slowish
> setting. You MUST use "neutral cure" versions - MOST versions use
> acetic acid cure which is potentially corrosive, bad on eyes etc and
> unnecessary. I use a neutral cure "marine" version which is marvelous
> for secondary anchoring of components which will be subject to
> mechanical shock. The glue sets to a "rubber" with excellent adhesion
> and a some flexibility which stops shock fracturing.

Silicon rubber attack any plastic close to it. It can also
cause headaches with 'nowash' solder fluxes after some
time. It's use is dissallowed in all automobile electronics
for this very reason. We even specify our injection
mould release agent to contain no silicon.

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za

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