Research On Reliability Of Au80Sn20 Solder Joint For Laser Diode Packages

Every country has worked out the corresponding decree to forbid using the solder containing lead in electronic industry because of the reinforce of demand on environmental protection, so it is very urgent to study a few late-model solders which are lead-free and replace the SnPb solder. In high-power electronics and optoelectronics packaging, Au80Sn20 eutectic solder is often used as hermetic sealing and die attachment material. But there is not a perfect conclusion on the mechanical property of Au80Sn20 solder, especially creep property under high temperature. The paper studied the mechanical property of Au80Sn20 solder by the indentation test and creep tension test at first, and inferred the constitutive equations of Au80Sn20 solder.Au80Sn20(AuSn) solder and Sn95.5-Ag3.8-Cu0.7-0.01CNT(SnAgCu) solder were chosen in the LD packaging. There were two kinds of bonding configurations: face-up and face-down about LD chip during the packaging process. The soft ANSYS was used to carry out temperature cycling test on the MCM assembly parts, and the impact under the different bonding configurations on the reliability of AuSn solder joint was studied. Conclusion is as follows:The marginal corners of AuSn solder joint are the most dangerous for the face-up and the face-down bonding configurations. Face-down bonding configuration is better from the reliability of solder joint point of the view; Face-up bonding configuration is better from the reliability of LDs point of the view, but the face-down bonding configuration should be chosen from the heat transfer and electrical characteristic of LDs point of the view. It is found from the analysis of MCM that the site of peak stress lay in the marginal corner of the Ni barrier layer which is under the AuSn solder joint under the low temperature state; lay in the edge of the Ni barrier layer which was above the SnAgCu solder joint under the high temperature state, they are the most dangerous in MCM assembly parts. The creep curve and strain curve of maximal creep point in AuSn solder joint and the SnAgCu solder joint are contrasted, it is found that AuSn solder have the higher strength and creep resistance.