Study on fatigue strength characteristics for solder joints

Daisuke Kaneko, Hirotsugu Inoue, Kikuo Kishimoto, Masaki Omiya, Masazumi Amagai

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Recently, preventing environmental pollutions, Pb-free solders are about to replace Sn-Pb eutectic solders. Sn-Ag-Cu alloys are leading candidates for Pb-free solders. However, Sn-Ag-Cu alloys were not enough to meet severe board level reliability requirements. In particular, thermal fatigue failure still has the problem. The interfacial strength decreases with intermetallic compounds (IMC) formation between solders and electric pads. Because IMC is brittle, the growth of IMC strongly affects the reliability of solder joints. However, for lead-free solder joints, the effects of IMC layer development on fatigue strength have not been studied well. In this study, in order to inhibit the IMC formation, 6 kinds of nano particles of metal (Cu, Ni, Co, Pt, In, Sb) were added to the solders based on Sn-Ag. We carried out board level fatigue tests and observed and conducted elemental analysis of cross-section surface of solders. And then we considered the relation of the fatigue life of several lead free solder joints and the change of the IMC layer by thermal aging. We aged the specimens in the isothermal chamber under 150°C for 0 to 20 days. As a result of the fatigue tests, about the solder including nickel, the fatigue life after aging is longer and fatigue strength reduction after aging is more lowered than the other solders. And the results of observation showed that IMC layers grow grained and the irregularity of interface between the IMC layers and the solder layers is smaller about the solder including nickel. So we consider that that improves resistance to crack advance, and then the solder showed the higher fatigue strength.

Original languageEnglish
Title of host publicationEMAP 2007- International Conference on Electronic Materials and Packaging 2007
Publication statusPublished - 2007 Dec 1
EventInternational Conference on Electronic Materials and Packaging 2007, EMAP 2007 - Daejeon, Korea, Republic of
Duration: 2007 Nov 192007 Nov 22

Publication series

NameEMAP 2007 - International Conference on Electronic Materials and Packaging 2007


OtherInternational Conference on Electronic Materials and Packaging 2007, EMAP 2007
Country/TerritoryKorea, Republic of

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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