Nonhermeticity of Polymeric Lid Sealants

Organic adhesives are useful lid sealants because they are processed at low temperatures, are inexpensive, and are easy to rework. However, there has been concern about the degree of protection organics can provide moisture-sensitive components. Data presented in this paper show that organic adhesives can seal packages which pass gross and fine leak tests but allow water vapor to permeate rapidly. Permeation measurements on hybrid microcircuit packages gave seal permeabilities of 3-7 x 10^-11g/cm-s-torr; these permeabilities agree with those listed for epoxies in the literature. With this permeability range and the package configuration used in this study, the interior humidity of a package will reach 50 percent of the exterior humidity in 6-10 h.