iNEMI Project on Process Development of Bisn-Based Low Temperature Solder Pastes - Part IV: Comprehensive Mechanical Shock Tests on Pop Components Having Mixed BGA Bisn-Sac Solder Joints
Authors: Haley Fu, Jagadeesh Radhakrishnan, Morgana Ribas, Raiyo Aspandiar, Babak Arfaei, Kevin Byrd, Jimmy Chen, Shunfeng Cheng, Qin Chen, Richard Coyle, Derek Daily, Sophia Feng, Mark Krmpotich, Scott Mokler, Brook Sandy-Smith, Kok Kwan Tang, Greg Wu, Anny Company: iNEMI, Intel Corporation, Alpha Assembly Solutions, Physics Department, Binghamton University, Flex, Eunow, Nokia, Senju Comtek Corp, Celestica, Microsoft Corporation, Indium Corporation and Lenovo Date Published: 10/14/2018
Abstract: Development of low temperature soldering of handheld and mobile computer board products is burgeoning because the lowering of peak reflow temperatures from the current 240oC+ level for SnAgCu (SAC) solder paste to below 200oC for BiSn based solder pastes has a triad of benefits -economic, environmental and technical. The inherent brittleness of the bismuth phase in the BiSn solder is its major drawback and has stunted its growth for use in many electronic products. Recently, solder suppliers have developed ductile Bi-Sn metallurgical and resin reinforced formulations of solder pastes to overcome this drawback. In this study, many of these newly developed solder pastes systems were evaluated. Using these solder pastes, SAC ball Package-on-Package (POP) components were assembled on B111A JEDEC Standard design boards, which were subjected to mechanical drops until failure. Results show that though there was some improvement in the mechanical shock resistance of the mixed alloy solder joints formed using the ductile metallurgy solder pastes and even significant improvement for the resin reinforced formulations over those formed with the baseline eutectic Bi-Sn formulations, this improvement was still not up to par with that of SAC solder joints.