Moisture absorption and bakeout characteristics of rigid-flexible multilayer printed wiring boards.

摘要

Moisture absorption and bakeout characteristics of Allied-Signal Inc., Kansas City Division (KCD) rigid-flexible printed wiring boards were determined. It was found that test specimens had absorbed 0.95 weight percent moisture when equilibrated to a 50 percent RH, 25(degree)C environment. Heating those equilibrated specimens in a 120(degree)C static air oven removed 92 percent of this absorbed moisture in 24 h. Heating the samples in a 80(degree)C static air oven removed only 64 percent of the absorbed moisture at the end of 24 h. A 120(degree)C vacuum bake removed moisture at essentially the same rate with parylene slowed the absorption rate by approximately 50 percent but did not appreciably affect the equilibrium moisture content or the drying rate.