SMTA International Conference Proceedings

The Quantitative Assessment of Mixed BGA Joint with the Elimination of Low-Melting Point Alloy Re-Melting Process

Authors: Hongqin Wang, Guanghui He and Daojun Luo
Company: China Electronic Product Reliability and Environmental Testing Institute
Date Published: 9/27/2015   Conference: SMTA International

Abstract: A careful experimental investigation was undertaken to evaluate the soldering process and the reliability of solder joints of SnAgCu PBGA components formed using the Sn- Pb solder paste. Initially, a series of the reflow soldering profiles were developed to assure the complete mixing of the SAC ball and Sn-Pb solder. Analysis of as-assembled solder joints revealed that the degree of mixing between the BGA SAC ball alloy and the Sn-Pb solder paste varied with the different reflow soldering profile. The peak reflow temperature was observed to have a significant impact on the solder joint microstructural homogeneity.

Serious crack defects of the complete mixed solder joints happened after the waving soldering process. Then a series of the reflow soldering profiles and tests were developed to solve the crack phenomenon and the mechanism of the crack phenomenon was illustrated with the quantitative assessment of mixed solder joints.

The reliability of mixed solder joints after optimazaiton was studied with an accelerated thermal cycling(ATC) test in the temperature range of -40C to 125C for a maximum of 3000 cycles in accordance with IPC 9701A standard.

Key Words: 

backward process, lead-free PBGA, mixed solder alloy, reliability

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