| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 96 === The binary Cu/Sn soldering system is the most important joint system in the current IC packaging and assembly industry. Although, the simple Sn/Cu reaction has been studied for a very long history, still, there are lots of research going on to understand it more. The scallop-type Cu-Sn compound grains formed at the Sn/Cu joint interface have reported by numerous researchers. Yet, none of them describe the relationship between the properties of Cu substrate and interfacial reaction. Also, the Cu consumption is a typical issue for Pb-free solders jointed with Cu-based bond pad. In this thesis, we will study the correlation between the microstructure of Cu substrate and the interfacial reaction.
In this investigation, the Cu foils were performed by metallurgical examination and XRD analysis to examine the grain size morphology and preferred orientation distribution. In Cu consumption experiments, 350 μm Sn solder balls were placed on the pre-fluxed Cu foils and reflowed on the hot plate at 250 °C for 1, 5, 10, and 15 minutes. We found that the Cu consumption of Cu substrate with the (200) plane is larger than that with the (220) plane, and it is also decreasing with increasing grain size of Cu. In IMC morphology experiments, 0.1 g pure Sn were placed on the pre-fluxed Cu foils and reflowed on the hot plate at 250 °C for 30 minutes. From the observation, the IMC morphologies would be different due to the grain size and preferred orientation of Cu substrate.
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