If you are talking outer space you are probably talking polyimide boards and
other special materials, not the standard FR4. When we deal with the
polyimide for space application, we do bake the boards just before assembly.
This is treated as a special case, but polyimide is far from having the same
chemistry as Ye old epoxy based FR4.

Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
e-mail: [log in to unmask]

-----Original Message-----
From: Dieselberg, Ron [mailto:[log in to unmask]]

We have been vacuum baking PWB's for about 15 or more years. There has never
been a documented failure or problem with baking on our products many of
which go into outer space. We normally bake before assembly, conformal
coating and staking. When not in process the boards are stored in a dry
nitrogen atmosphere. Baking has improved the quality of our vapor phase
reflow operation and has reduced soldering and board defects. I suppose that
if you "toast" the boards you could suffer some problems, but for us it has
been nothing but improvements. Some of our customers have specified that the
boards be pre-baked and the manufacturers of our conformal coatings have
highly recommended it to prevent moisture entrapment. Until we encounter a
problem or failure we will continue to bake as we have done in the past.

Ron Dieselberg

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