We used to bake [100*C for 6 hours] all of our boards, but no longer bake at all.
Before going off, your bake recipe is probaly OK. If anything, it's probably too short. Consider measuring the weight of wet boards, baking for a time, measure, bake, etc. to determine a proper bake time.
Boards are hydroscopic. If barrel plating is below 1 thou, the absorbed moisture vents through the barrels at soldering temperature. This causes voiding and volcanos in the solder. Both are very tough to rework.
Consider changing the situation to stop this non-value added baking [In fact baking is negative value added, because it makes it harder to solder a good board.]: * Suppliers must provide board with a minimum of 1 thou of copper on plated holes. * Buyers must buy no stop greater than three months in advance of production. * Boards must be stored in a controlled environment [ANSI-J-STD-001: 18-30*C, 30-70%RH]
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