The whole idea behind baking of standard FR4 or tetrafunctional laminates
after oxide is merely to dry the cores. The is no curing or functional
purpose other than just drying of the reduced oxide and laminate.

Typically, the cores are baked in the oxide racks in a drop in oven. The
temperature needs to be slightly over 100C and typical times are 15 to 20
minutes. The reduced cores are very suseptible to staining and or
reoxidization if they are not 100% dry.

Excessive bake times and or temperatures will lead to reoxidation and loss of
acid resistance. This in turn can contribute to pink ring and or micro
delamination. The standard acid resistance test will allow you to see if you
have any significant loss of acid resistance. I would suggest any thing above
0.125mg/cm2 to be not acceptable.
I hope this helps.

Regards,
Chris McGary
Dexter Electronic Materials

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