Hello fellow designers,

One of our products uses 3 PCBA's made on our internal surface mount line. After the PCBA's are created, they are hand soldered together with through hole components and then put into a housing which is then filled with an Epoxy resin (Stycast 2075).

We are wondering about moisture update on the PCBA's between the surface mount process and our hand soldering process. There is some concern that any moisture absorbed would be trapped by the resin and therefore lead to premature electrical failure in harsh applications. Our factory is located in Ontario and is air conditioned in the warm months.

Option 1 (best case)
We would like to avoid any special drying or baking process on the PCBA's.
*       Does anyone think there would be a risk in doing this?

Option 2
We could put them in a dry cabinet. The one we have is a Dr. Storage T40W-600. It runs at 40C and <=5%RH.
*       Is this temperature of 40C enough to dry out the PCBA's?
*       How long should they be stored in there before use?

Option 3
We could buy a baking oven similar to what is used for components prior to re-flow.
*       What temperature and duration would be suitable?

I have some IPC standards (J-STD-033D, 1601A) but I'm not sure how to relate our PCBA's to the tables of drying/baking conditions.

With Best Regards,
Mike Messenger, P.Eng, PMP

Siemens Canada Limited
Manufacturing Engineer
PD PA PI LWT IE
1954 Technology Drive
Peterborough, ON K9J 7B1
705-740-7025
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