Low-Ag and No-Ag Lead-Free Solders Highlighted

Published:2011/12/30 0:43:00 Author:Amy From:SeekIC

Nihon Superior, a supplier of advanced soldering materials, has presents the effectiveness of Cu and Ni as the crucial elements in constructing a stable IMC layer in lead-free soldering.

As the micrographs below, the fluxed copper/OSP test boards were exposed to the solders for five seconds in a mini-wave machine with a pot temperature of 255°C. It was found that after 528 hours at 150°C, the intermetallic compound on the board soldered with Sn-0.7Cu-0.05Ni was smoother with slower growth of Cu3Sn and no cracking. By contrast, the IMC layer in Sn-0.7Cu-0.3Ag and Sn-0.7Cu-0.3Ag-0.1B with additions of 0.3 Ag and 0.3 Ag+0.1Bi was uneven with growth of Cu3Sn and cracking (Figure 2).



Based on Sn-0.7Cu-0.05Ni, Nihon Superior’s SN100C solder also integrates a Ge addition as an antioxidant and flow promoter.

Silver-free, lead-free solder, SN100C now has a track record of more than 12 years of successful delivery of high productivity and high reliability. The first of the new SN100C Advantage Series, SN99CN, builds on the strengths of the Sn-Cu-Ni formulation of SN100C with a controlled addition of silver. Both SN100C and SN99CN include Cu and Ni to form the stable IMC (Cu,Ni)6Sn5.

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