PCB never expire, they just become more difficult to solder. [Many shops impose �shelf life� periods for their boards, but they aren�t going to discard the boards if the exceed the limits, unlike they would with some other process materials.]
IDENTIFYING THE OPTIMAL BAKING PARAMETERS. The optimal baking parameters are dependant on: * Type of materials from which the board is fabricated. <= FR-4 is baked differently / has different baking requirements than flex. * Amount of moisture that your boards have absorbed. * Loss of solderability on the pads. * Thickness of PTH / via plating [and maybe other board construction issues].
In determining these parameters, try this: * Weigh your boards. * Search the fine SMTnet Archives for guidelines and opinions on baking boards. * Bake the boards for maybe half the expected time. * Weigh your boards, partially toasted. * Solder the [unloaded] board. * Assess the solder connections on the board. * Plot data. * Repeat until bored.
RELIABILITY ISSUES. If you don�t get �crazy�, there are no reliability issues with baking. A wild a crazy board baker would do things like: * Running the oven too hot. * Ramping the temperature to quickly. * Allowing BIG temperature swings.
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