Thermal fatigue of solder flip-chip assemblies

Recently several low cost alternatives to the flip-chip interconnection technology have been investigated. The scope of the paper is a reliability study of flip-chip assemblies on various substrates (mainly FR4). The deterioration (characterised by the electrical resistance) of 63Sn37Pb and of 96.5Sn3.5Ag bumps caused by both thermal cycling and thermal shock will be described. Samples with and without encapsulated flip-chip interconnections have been investigated. It has been found that the relationship, the number of the thermal cycles to destruction of the bumps as a function of chip size, and bump height obeys the Coffin-Manson equation. TV tuner circuits are a potential application of flip-chip technology. It has been experimentally verified that flip-chip contacts exhibit superior high frequency performance compared to those assembled in chip and wire and/or in using SO package.