Homebrew PCBs

--- Adam Seychell <adam_seychell@...> wrote:

> Then in that case most of the retailers have got the
> 
> labeling wrong. If they call polyester resin "Epoxy"
> then 
> what do they call polyester resin ?
> A shop I went to made distinct differences between
> the epoxy 
> resins and polyester resins they sold. If I buy a
> two part 
> resin which part A is labeled "contains %100 epoxy"
> and part 
> B is labeled "contains: > %70 aliphatic amines",
> then is 
> that  polyester or epoxy ? , it doesn't need
> autoclaving
> 
> 
Any resins that are mixed with an amine are epoxies.
Bisphenol-A is an amine. If your not having to
autoclave it, then the 70% aliphatic amines are mixed
with 30% (Or maybe less...) of something that causes
an exothermic reaction. Epoxy has got to have heat to
cure. The strength of the non autoclaved, but cured
expoxy would, in my opinion, not have the strength
(But it would still be stronger than polyester resin)
that epoxy that was cured in an autoclave would have.
The stuff sold in places like home depot say epoxy,
but are polyester resins according to the ingredients
listed on the packaging. You are obviously purchasing
your resins from a company that sells a lot of these
types of composite materials (A specialty store of
some type?)


 All of the epoxy resins I have had experience with
(Back when Lockheed-Grumman was Grumman Aerospace...)
require autoclaving. Basically, we had a mold, put the
electronics in the mold and poured the resin in with
the electronics. Then, we hooked up a vacum to it
(Around 60 psi) to remove any air bubbles in the resin
and sent it to the autoclave. When we would get the
device back from the autoclave we would pull it out of
the mold. It would have a nice, smooth conformal
finish on all sides. 


Best regards


Marvin Dickens
Alpharetta, Georgia  USA

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