Gas permeability of adhesives and their application for hermetic packaging of microcomponents

The use of adhesives with low gas permeability in packaging microcomponents provides a simple, low-cost alternative to the standard techniques for hermetic packaging. The permeability to helium of various epoxy resin adhesives was determined by means of a mass spectrometer in reference specimens of defined dimensions. The adhesive with the lowest permeability to helium was chosen to bond an evacuated LIGA gyrometer package (flatpack, volume = 1.4 cm(3)). For comparison, a few packages were closed by laser welding. Subsequently, the pressure rise in the sealed packages due to gas permeation and desorption from the walls was measured by the integrated microsensor, and the permeation rate was determined. The permeation rates of as low as 10(-17) m(3)/s achieved in bonded packages are comparable to those measured in laser welded packages.