Joining characteristics of various high temperature lead-free interconnection materials

The degradation mechanism of the interface between Agepoxy conductive adhesives (CAs) and Sn plating under a humid condition was examined. As the results of TEM analyses, two different types of oxide layers, SnO and SnO₂ phases, were found to be formed at the interface. These Snoxides at the interface is the root cause of the interfacial degradation. A pendulum impact testing system was proposed as the standard method of the CAs joint evaluation. The potential of newly-designed Zn-Sn alloys as high temperature lead-free solders was also evaluated, with particular focus on the interface stability. Zn-Sn alloys can maintain interconnection between a Si die and a DBC substrates coated with Au/TiN thin layer until 2000 cycles of thermal cycling test (-40degC~125degC). Zn-Sn possesses a great potential as lead-free high temperature solder alternatives.