Effects of Thermal Aging on the Interfacial Reaction between Zn-25Sn-xTi Solder and Cu Ni Substrates

  • 劉 季銘

Student thesis: Doctoral Thesis


This study investigated the effects of minor addition of Ti on the interfacial reactions and microstructure variation of Ni/25Sn-xTi/Ni Cu/Zn-25Sn-xTi/Cu solder joints during thermal aging IMC formed between Zn-25Sn-xTi solder and Ni substrate was identified as Ni5Zn21 The interfacial Ni5Zn21 growth was controlled by the chemical reaction at first After the addition of Ti the activation energy of Ni5Zn21 growth decreased from 63 24 kJ/mol to 37 74 kJ/mol and the rate-controlling step changed to the volume diffusion According to the grain morphology Ni5Zn21 could be divided into three different zones: nucleation zone columnar zone and mixed zone Ni5Zn21 grains in columnar zone grew significantly after aging treatment The interfacial IMCs formed between Zn-25Sn and Cu substrates were CuZn5 and Cu5Zn8 CuZn5 phase transformed to Cu5Zn8 after aging at 250℃ for 36h in this study The activation energy of Cu5Zn8 and total IMC (CuZn5 + Cu5Zn8) growth changed from 39 74 to 35 91 kJ/mol and 48 91 to 44 92 kJ/mol respectively Ti addition slightly lowered the activation energy of Cu-Zn IMC growth CuZn5 consisted of extremely fine grains while Cu5Zn8 was comprised of coarser grains The total IMC growth during aging processes was mainly ascribed to the increase in the number of the newly-formed finer Cu5Zn8 grains between the original Cu5Zn8 IMC and Cu substrate
Date of Award2020
Original languageEnglish
SupervisorKwang-Lung Lin (Supervisor)

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