SMTA International Conference Proceedings


Production Testing Of Ni-Modified SnCu Solder Paste

Authors: Karl Seelig, Timothy O’Neill, Kevin Pigeon & Mehran Maaleckian; Andy Monson and Walter Machado; and Chrys Shea
Company: AIM Solder, Hayward Industries, HRI (formerly Goldline Controls), Shea Engineering Services
Date Published: 10/13/2013   Conference: SMTA International


Abstract: Low-silver and no-silver lead-free PCB solder alloys represent substantial cost savings over SAC alloys that contain 3% silver. Many wave solder operations use silverfree alloys for through hole soldering, and SMT operations are also beginning to adopt the alloy for surface mount soldering.

This paper reviews two case studies that test Ni-modified SnCu solder paste on mixed technology circuit assemblies which currently use SAC305 in production. The major differentiator between the two cases is the reflow profile: In one case, the SAC profile was considered nearly perfect for the SnCuNi alloy, peaking at 245°C. In the other case, thermally sensitive components constrained the profiles to peaking near 235°C, only 8 degrees above the silver-free alloy’s 227°C melting temperature. This important case is used to explore the lower limit of reflow capability and compare it against the baseline provided by the typical thermal process.

The performance of the solder pastes and joint formation in both cases are evaluated using numerous assembly metrics and reliability tests, including visual and automatic optical inspection, X-ray inspection, in-circuit and functional testing, optical microscopy, thermal aging, thermal cycling and shear testing. The results are presented and discussed.

Key Words: 

Lead-free solder paste, silver-free solder paste, Sn100C, Ni-modified SnCu,



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