| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 97 === The formation of intermetallic compounds (IMCs) helps to provide good metallurgical bonding between solders and substrate in the microelectronic packing applications. Previous reports pointed out that the tensile stress is a main cause induces the fracture of solder joints during the Ball Pull tests. Owing to the above-mentioned reasons, this study attempts to find out an optimal interfacial IMCs growing condition between SAC305 and copper substrate through performing the solid-state bonding process with 210�薡 IMCs growth treatments and different time (5, 7.5, 9, 10, 15, 20 hrs). The variation of interfacial adhesion strength, bonding reliability and failure behaviors were examined. Tensile tests were applied to measure the interfacial adhesive strength of SAC305/Cu bonding.
The tensile test results have obvious difference with different IMCs growth treatment time. With 7.5~10 hrs IMCs growth treatment, average adhesive strength are around 20MPa and much higher than others. Besides, the results of Weibull analysis of 7.5, 9, 10 hrs show the adhesive strength and the bonding reliability are decreased with increasing heating time, and 7.5 hrs specimens has the highest characteristic strength of SAC305/Cu interfacial bonding, less data fluctuation and a left-shift wear-out failure model of increasing failure rate (IFR). As the result, the optimal IMCs growing condition is 7.5 hrs.
From the cross-sectional observation of SEM and Weibull model, the cracks propagate through the Cu6Sn5 IMCs layer can help reliability and adhesive strength increase. Besides, according to the results of EPMA analysis, the forming of Ag3Sn at the interface of SAC305/Cu is propagate with IMCs growth treatment time and it may be one of the reasons that average adhesive strength is decease with IMCs growth treatment time.
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