I'd go with silicon Les ;
when in open outdoor elements ; anything else is struggling to meet it's
resilience .
I've have a various profiles, shapes and application prototypes being truly
life tested
anchored in cliff rock in pounding surf for a couple of years on one of my
locations :
everything else (epoxy, metals, urethanes, cements, socalledsuperglues,
etc.)
gave up within months in waves, salt, sand, and UV.
Even crabs don't like it ; human's ain't around (need to absail to it) ;
so silicon lives well in most applications ;
(unless misdesigned by Dow)
Your's is obviously design dependent as well : experiment .
Paul Klasek
ResMed
PS
CLEAR moisture fav is definitely Si.
But you have to have design consideration on application :
For example lip inwards to hold the silicon plug = passive mechanics needed
;
silicon is a sealant , not adhesive .
I'd distrust adhesives in general anyhow (aging)
-----Original Message-----
From: Les Hughson [mailto:[log in to unmask]]
Sent: Wednesday, 22 September 1999 10:42
To: [log in to unmask]
Subject: [TN] Moisture Proof Encapsulation
I have a small temperature sensor pcb which is to be sealed into an
enclosure, one side of which is in contact with warm water and may leak
slightly, the other side is in air, probably encountering condensation.
My problem is how to get impartial advice on what is the best type of
encapsulation compound to use. e.g. Silicone Rubber, Epoxy Resin,
Polyurethane Resin etc. Various manufacturers all have their own range of
products and will recommend one from there range but I have not found a
single source which manufactures the various different types of compound
listed above and can tell me which would be best.
So. Does anyone have any experience of comparing these different types of
materials...
Silicone Rubber.
Epoxy Resin.
Polyurethane resin.
Others?
Is there a clear favourite for moisture protection?
Any advice would be much appreciated. :-)
Les Hughson, BEng.
Product/Software Engineer
Spa-Quip Ltd
Tel (+649) 415 8622
Fax (+649) 415 8621
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