RELIABILITY STUDY AND SOLDER JOINT MICROSTRUCTURE OF VARIOUS SnAgCu CERAMIC BALL GRID ARRAY (CBGA) GEOMETRIES AND ALLOYSAuthors: Marie Cole, Matthew Kelly, Mario Interrante, Grego
Company: IBM Corporation
Date Published: 9/24/2006 Conference: SMTA International
Additional studies were completed on another PCB test vehicle using a water soluble Sn3.8Ag0.7Cu (SAC 405) solder paste. Geometry factors such as ball, package pad and card pad diameters were evaluated. Package ball alloys SAC 305 and SAC 405 were compared. Mixed assembly performance under slightly different conditions was compared to the results from the above assembly matrix. Solder joints formed were examined “as assembled” and also after accelerated thermal cycling (ATC) using optical and Scanning Electron microscopy, EDX and X-ray methods.
This paper contains references to "lead free" solder alloys. Lead free has become an industry standard term meaning that the solder alloy should contain less than the RoHS Directive limit (1,000 ppm) for lead. It does not mean that the solder alloy will necessarily contain no lead at all.
Key words: SAC CBGA, SnAgCu CBGA, mixed assembly
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