Thermal fatigue properties and grain boundary character distribution of lead-free Sn-1.2Ag-0.5Cu solder interconnects on WLP

Shinichi Terashima, Takayuki Kobayashi, Shinji Ishikawa, Tsutomu Sasaki, Kohei Tatsumi, Masamoto Tanakaupu

Research output: Contribution to conferencePaper

Abstract

Both drop reliability and thermal fatigue properties of modified-LF35, a commercial low-silver type solder, and Sn-xAg-0.5mass%Cu (x: 1 and 3 mass%) lead-free solders on Casio's wafer level packages were discussed. LF35 had superior drop reliability than SAC105 or SAC305. However, LF35 of a standard type and SAC105 showed the shorterr thermal fatigue life than SAC305. Hence, thermal fatigue properties of LF35 was improved by modifying its chemical composition. Both cracks, which were initiated by thermal strain, and grain-boundary damage due to grain-boundary sliding degraded the thermal fatigue lives. From a microstructural observation using orientation imaging microscopy (OIM), both modified-LF35 and SAC305 suppressed coarsening of tin grains due to thermal strain as compared with SAC105. Moreover, both modified-LF35 and SAC305 showed a larger amount of coincidence site lattice (CSL) boundaries than SAC105. It is suggested that not only smaller tin grains but also larger amount of CSL boundaries observed in modified-LF35 and for SAC305 suppressed crack propagation and grain-boundary damage.

Original languageEnglish
Pages73-78
Number of pages6
Publication statusPublished - 2008 Dec 1
Externally publishedYes
EventIMAPS International Conference and Exhibition on Device Packaging - In Conjunction with the Spring Conference on Global Business Council, GBC 2008 - Scottsdale, AZ, United States
Duration: 2008 Mar 172008 Mar 17

Conference

ConferenceIMAPS International Conference and Exhibition on Device Packaging - In Conjunction with the Spring Conference on Global Business Council, GBC 2008
CountryUnited States
CityScottsdale, AZ
Period08/3/1708/3/17

Keywords

  • Drop reliability
  • Grain boundary character distribution
  • Lead-free solder
  • Orientation imaging microscopy
  • Sn-Ag-Cu
  • Thermal fatigue

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

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    Terashima, S., Kobayashi, T., Ishikawa, S., Sasaki, T., Tatsumi, K., & Tanakaupu, M. (2008). Thermal fatigue properties and grain boundary character distribution of lead-free Sn-1.2Ag-0.5Cu solder interconnects on WLP. 73-78. Paper presented at IMAPS International Conference and Exhibition on Device Packaging - In Conjunction with the Spring Conference on Global Business Council, GBC 2008, Scottsdale, AZ, United States.