PCB007 Magazine

PCB-Jan2014

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f e at u r e by Shigeo Hashimoto, et al.[1] As previously published by SMTA in the proceedings of SMTA International 2013. Abstract The ability to plate fine patterns, the solder joint reliability (SJR) and the wire bonding reliability (WBR) of the electroless Pd/Au (EPIG) deposit were compared with the electroless Ni-P/Pd/Au (ENEPIG) deposit. SJR was evaluated by high-speed shear test (HSS) when comparing Sn-3.0Ag-0.5Cu with Sn-1.2Ag-0.5Cu-0.05Ni as the composition of the solder ball. When using Sn-1.2Ag-0.5Cu0.05Ni as the solder ball for EPIG film, the uniform alloy layer was formed and SJR became excellent. 12 The PCB Magazine • January 2014 EPIG deposits with thicker Pd had good WBR because the Pd layer prevented Cu diffusion to the top of Au surface after heat treatment. And when Au thickness of EPIG deposit was thicker, WBR became better because the ratio of Pd on the top surface was kept lower after heat treatment. On the other hand, WBR after heat treatment was improved by applying plasma treatment on Au surface. Introduction In recent years, the electronic devices, such as a smartphone and a tablet PC, have been miniaturized. Therefore, CSP (chip size package) used inside the electronic devices have also been miniaturized, and the space of the wiring lines have become narrower every year. Some of latest packages have the space of the wiring line of 15 µm or less. At that time, if electroless Ni-P

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