Metallurgical Bonding Systems for HighTemperature Electronics

The chip-to-package metallurgical interconnections that may be used in high-temperature electronic environments are described. These interconnections are primarily wire bonded, but include TAB(tape-automated bonding) where appropriate. Details of the most studied bonding system (Au-Al), with emphasis on its failure modes and mechanisms, are given FIRST for an understanding of the problems that may occur in interconnection metallurgies. Later, these failures are compared to many other possible metallurgical bonding systems that may be considered for hightemperature environments such as Al-Cu, Au-Cu, Ag-Au, Al-Ni, Au-Pd, Al-Pd, Al-Ag,and mono-metallic interconnections. The reliability considerations are discussed in terms of maximum temperatures and times in various high-temperature environments. Bond reliability at high temperatures is often dependent on any impurities in the weld interface as well as completeness of the weld. Therefore, these problems are discussed in context.