Effect of Solder Mixture on Joint Reliability of Repaired Components

摘要

There have been numerous recent reports of research projects concerning the development of joint aspects of lead-free solders in mass production technology. In contrast, little research has been published on manual soldering. Especially, information is lacking on the effect of solder mixture on joint reliability, which can be problematic in the case of component repair, when lead-free solders are introduced. This paper describes component joint reliability under temperature cycling test (-40°C～125°C:1h/cycle). The components tested were joined using wire solder of such composition as Sn-3Ag-0.5Cu or Sn-40Pb to substrates that had first undergone reflow process using solder paste of various compositions, such as Sn-3Ag-0.5Cu, Sn-2.5Ag-0.5Cu-lBi, Sn-8Zn-3Bi, and Sn-36.8Pb-0.4Ag. Sample components used were chip resistors of several dimensions, and TSOPs(Thin Small Outline Packages). The parameters of our investigation comprised type of solder, surface treatment of substrate electrodes and plating of component electrodes. The results indicate that some combinations of these parameters show a tendency toward weakening joints. On basis of these results, we will investigate the cause of this weakened tendency by observing metallic structure.