I, and our board suppliers, have looked through IPC-6011, 6012, 600, 610 and
most of the other pertinent standards and cannot find an answer to this
question:

How long should multi-layer printed circuit boards be left out in a
controlled ambient environment (standard factory temp/humidity) before
pre-baking the boards becomes necessary to dry out any accumulated moisture
in them? We would like to minimize potential board delamination due to
trapped moisture in the FR4 or polyamide layers (which can expand rapidly
when the board is placed through a reflow oven or solder wave).

Does anyone want to wade in on this one? We have identified a standard for
pre-baking IC components before use in this type of high-heat environment,
but cannot find any standard or specification pertaining directly to PCBs
themselves. I suspect it will have to take into account the material used,
number of layers, the definition of "standard factory temp/humidity" and
other things related to the board and the environment it is stored in prior
to use.

Any help in this regard would be appreciated.

Thanks!
Dale Ritzen
Quality Manager
Austin Manufacturing Services
9715A Burnet Road,  Suite 500
Austin, TX  78758

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