Microelectronics Reliability, 87, pp. 232-237. (2018) DOI: 10.1016/j.microrel.2018.06.010

Novel Silver Die Attach Technology on Silver Pre-Sintered DBA Substrates for High Temperature Applications


S. Nishimotoab, S.A. Moeinib, T. Ohashia, Y. Nagatomoa, and P. McCluskeyb
aCentral Research Institute, Mitsubishi Materials Corporation, 1-600, Kitabukuro-cho, Omiya-Ku, Saitama 330-8508, Japan
bCenter for Advan.ced Life Cycle Engineering (CALCE), Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, United States

Abstract:

Currently, Ag die-attach techniques, using nano-silver particles, are of high interest for manufacturing of wideband-gap(WBG) power module due to their high-temperature operation capability. However, the high cost of silver and complicated processing requirements are the main driving force in the search for simpler and more cost-effective attached technologies. In this study, a new die-attach technique based on silver die-attach, without conventional Ag-paste, for high-temperature applications is developed. Glass containing Ag paste was pre-sin­tered on the OBA substrates, and later on, semiconductor dies were simply placed on this pre-sintered Ag layer and attached under heat and pressure. The samples were tested under shear and thermal cycling loadings ( -45 oC/250 oC) to evaluate the quality and reliability. Destructive and non-destructive analysis methods, such as Scanning Acoustic Tomography and cross-section observation, were used to identify fracture modes. The samples demonstrated sufficient shear strength and high thermal reliability. Furthermore, the effects of Ag re­crystallization, grain growth and rearrangement of the voids are considered to be the main fracture factor of conventional Ag die-attach joints based on sample's cross-sections.

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