What solder-ability risks are there from uncontrolled storage and only baking before use, particularly in a high humidity environment?

What solder-ability risks are there from uncontrolled storage and only baking before use, particularly in a high humidity environment?

  • If products are stored outside dry-packs in a high humidity environment, they can absorb moisture between the leads and the package.   If the devices are not completely baked out according to industry standards, that moisture can boil during solder re-flow and pop the package open.   Also, if the packages are left exposed for an extended period, the leads on the package may oxidize, which will result in unreliable solder joints in assembly.   Lead oxidation will not be reversed by bake-out.   Lead oxidization can be removed with flux, but this is a tedious procedure not suitable for volume assembly.