Mark: The maximum service temperature for unfilled optically clear epoxy is
about 180 C. It "may" survive short exposures in the reflow oven of the 250 C
range without yellowing or breaking down but you're pushing it. You may want to
consider a clear silicone system which has better high temperature resistance.

As far as moisture absorption most high temp unfilled epoxies should be less
than 0.5% B.W. Is this good enough to meet your requirement?

The issue of air bubbles is up to you to control. This will probably require a
vacuum de-airing step of the material prior to encapsulation and possibly
another one after, prior to cure.

Contact: Grace Speciality Polymers; Atlanta GA.  404-696-4565
         MasterBond Inc. Hackensack N.J.   201-343-8983
         TRA-CON Inc. Medford MA.  617-381-5550

                                                Regards
                                                        Michael Barmuta
                                                        Staff Engineer
                                                        Fluke Corp.
                                                        Everett Wa.
                                                        425-356-6076


On Tue, 11 Aug 1998 13:20:04 -0700 Mark [log in to unmask] wrote:

> From: Mark [log in to unmask]> Date: Tue, 11 Aug 1998 13:20:04 -0700
> Subject: [TN] Optically transparent epoxy
> To: [log in to unmask]
>
> Technetters,
>
> I am looking for an optically transparent epoxies for use as a potting
> compound that can withstand IR reflow.  This epoxy must be very stable and not
> absorb moisture.  Also air bubble must be kept to a minimum.  Recommendation
> on manufacturers, suppliers, or specific products would be much appreciated.
> Also any information on reliability of these products would be also help.
>
> Thanks for your help,
>
> J. Mark Elliott
> Maxtek Components Corp.
> 503.627.3641
> [log in to unmask]
>
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