Mapping the Mechanical Properties of Solder with Nanoindentation
Publication Number: 5991-3686EN
Publication Date: 2015.01.28
Language: English
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Mapping the Mechanical Properties of Solder with Nanoindentation

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Electronic packaging reliability depends largely on the mechanical integrity of soldered interconnects. Thus, the purpose of this work was to use a new nano-indentation technique, Express Test, to map the hardness of a SAC 305 solder joint with gold plating. In this study after extended aging, the solder joint comprised three constituents: a tin-rich matrix, a bulk intermetallic AuSn4, and an interfacial intermetallic (Cu, Ni, Au)6Sn51. The softest material was the tin-rich matrix, which had a hardness of 0.51 ±0.07 GPa. The hardness of the bulk intermetallic was 2.12 ±0.18 GPa. The interfacial intermetallic had extraordinary hardness— greater than 8 GPa. Under uniform plastic strain, the mismatch in hardness between the interfacial intermetallic and surrounding material may increase the local stress intensity factor which drives interfacial fracture.