AU-AL SOLID-PHASE DIFFUSION FLIP-CHIP BONDING

A new flip chip bonding technique using An-Al solid phase bonding was developed. In this technique layer of Au and Al is formed by connectin g a driver IC with au bumps to an Al wiring board. In the conventional flip chip mounting method, the solder bumps formed on the LSI electro de are connected to the board by the reflow method. This method is dif ficult to apply to metal with weak solder wettability such as Al wirin g. Furthermore, the reflow method is difficult to apply to electronic equipment constructed with material that has low heat resistance such as liquid crystal display (LCD) modules. Therefore, assuming the appli cation to LCD panels with Al wiring, an investigation of connection co nditions, analysis of heat transmission, and identification of the Au- Al intermetallic compounds were performed. The results show that conne ction is mechanically and electronically stable, the LCD panel is not affected by the connection conditions such as temperature, the interme tallic compounds are Au5Al2 and Au4Al, and the final product is Au4Al. Furthermore, an LCD module was fabricated by bonding a driver IC with 80 mu m connection pitch to an LCD panel using Au-Al solid phase diff usion bonding. (C) 1997 Scripta Technica, Inc.