MECHANICAL AND ENVIRONMENTAL TESTS OF BRAZED CERAMIC MULTILAYER PACKAGES

Kovar pins were attached to tungsten-metallized, alumina ceramic packa ges with Ag-Cu alloys using a wide range of brazing process parameters that were systematically varied in a designed experiment. The impact of the brazing thermal process, furnace atmosphere, brazing filler met al composition, and brazing filler metal quantity on the performance o f ceramic pin-grid arrays was assessed through mechanical and environm ental tests. Metallographic analyses revealed that a wide range of bra zement microstructure, macrostructure, and base metal interaction were produced. Nevertheless it was found that these divergent conditions h ad no detrimental effect on the cofired ceramic performance as judged by the results of pin-pull tests after exposure to vibrational fatigue , thermal shock, salt-spray corrosion, and temperature-humidity cyclin g. The lack of ceramic degradation, despite exposure to more severe br azing conditions than previously reported in the literature, is attrib uted to the combined quality of the package design, the materials set, and the fabrication processes.