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Indexed by:会议论文

Date of Publication:2017-01-01

Included Journals:SCIE、EI、CPCI-S、Scopus

Page Number:1087-1091

Key Words:high pressure air; synchrotron radiation; microstructure; Ag concentration; growth activity energy; mechanism

Abstract:High pressure air blowing liquid solder and synchrotron radiation x-ray real-time imaging technology were used to study the interface reactions of Sn-XAg/Cu (X=0,1,3) joints during reflow with various soldering time under temperature of 250/275/300 degrees C. This experiment allows us in-situ observe the interfacial IMCs growth and completely avoids Cu6Sn5 precipitation from the solder in cooling stage to affect the morphology and thickness of interfacial IMCs. The study results show that the IMC morphologies are scalloped during the heat preservation stage at all three solders/Cu interfaces and the IMC grains are thinner but higher with containing Ag solder. With the Ag concentration increasing, the phenomenon is more obvious. Comparing with pure Sn solders, the Sn-Ag solders are observed with interfacial IMC of greater thickness. In addition, it is confirmed that Ag3Sn grains don't exist on the surface of existing Cu6Sn5 grains but in Sn-Ag solder at the heat preservation stage. It is also confirmed that the grain boundary diffusion determines the interfacial reaction. By calculating, the values of Q for Sn1.0Ag and Sn3.0Ag are 34.753kJ/mol and 29.884 kJ/mol, both smaller than Sn(35.141 kJ/mol). Namely, the Ag addition decreases the growth activity energy of IMC. The mechanism of Ag addition to affect interfacial reaction by changing the mirostructure of solder matrix and growth activity energy are also clarified, and then the morphology and thickness of interfacial IMCs can be controlled by alloy elements addition to improve the soldering reliability of electronic packaging.