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Indexed by:期刊论文

Date of Publication:2017-02-25

Journal:JOURNAL OF ALLOYS AND COMPOUNDS

Included Journals:SCIE、EI

Volume:695

Page Number:1436-1443

ISSN No.:0925-8388

Key Words:Thermomigration; Synchrotron radiation; Temperature gradient; Interfacial reaction; Zn addition; Dissolution

Abstract:Thermomigration (TM) caused by temperature gradient in micro solder joints is recently recognized as a crucial reliability concern for 3D packaging technologies. In the present study, the interfacial reactions in Cu/Pb-free solder/Cu solder joints have been in situ investigated under a simulated temperature gradient of 508 degrees C/cm by synchrotron radiation real-time imaging technology. Serious TM-induced Cu substrate consumption at hot end and abnormally fast TM-enhanced intermetallic compound (IMC) growth at cold end are clearly observed in pure Sn and Sn-Ag-Cu solder joints. However, significant retardation of the TM-induced Cu substrate consumption and the TM-enhanced IMC growth is realized by introducing Zn into the solders. The dissolution rate of the hot end Cu substrate and the growth rate of the cold end IMCs both decrease about three times as the Zn content increases from 0 wt% to 9.0 wt%. The improvement in TM resistance by Zn addition is attributed to the formation of Cu5Zn8 or Cu-6(Sn, Zn)(5) IMC at the hot end, the weakened diffusion of Cu atoms and the lowered driving force for IMC precipitation at the cold end. The molar heat of transport Q* of Zn is calculated to be 2.31 kJ/mol. (C) 2016 Elsevier B.V. All rights reserved.