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Thermal and mechanical properties of sintered Ag layers for power module assembly

Marcin Myśliwiec (Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Warsaw, Poland and Institute of Electron Technology, Warsaw, Poland)
Ryszard Kisiel (Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Warsaw, Poland)

Microelectronics International

ISSN: 1356-5362

Article publication date: 5 January 2015

Abstract

Purpose

The purpose of our paper is to investigate thermal and mechanical properties of Ag sintered layers used for assembly of SiC diode to Direct Bonding Copper (DBC) interposer. How SiC devices are assembled to ceramic package defines efficiency of heat transfer and mechanical support.

Design/methodology/approach

Ag microparticles, sized 2-4 μm and flake shaped, were used as joining material. The parameters of sintering process were as follows: temperature 400°C, pressure 10 MPa and time 40 min. It was found that after sintering and long-term aging in air at 350°C the adhesion is in the range of 10 MPa, which is enough from a practical point of view. The thermal properties of the SiC die assembled into a ceramic package were also investigated. In the first step, the calibration of the temperature-sensitive parameter VF (IF = 2 mA) was done and the relation between VF and temperature was found. In the next step, the thermal resistance between junction and case was determined knowing junction and case temperature.

Findings

For SiC diode with Au bottom metallization joined to the DBC interposer by Ni/Au metallization by Ag microparticle layer, Rth j-c is in the range of 2-3.5°C/W, and for SiC diode with Ag bottom metallization joined to DBC interposer with Ag metallization by Ag microparticle layer, Rth j-c is in the range of 4.5-5.5°C/W.

Research limitations/implications

In the future, research on thermal resistance of SiC diodes assembled onto the DBC interposer with Au and Ag metallization in the temperature range up to 350°C needs to be carried out. To do this, it necessary to find a solution for the attaches that leads to ceramic package able to work at such high temperature.

Originality/value

Obtained results are comparable with results mentioned by other studies for eutectic Au/Sn or SAC solder joints; however, the solution proposed by us can properly work at significantly higher temperatures.

Keywords

Acknowledgements

The work was supported by The National Science Centre, NCN, Poland (Grant no N N515 499240).

Citation

Myśliwiec, M. and Kisiel, R. (2015), "Thermal and mechanical properties of sintered Ag layers for power module assembly", Microelectronics International, Vol. 32 No. 1, pp. 37-42. https://doi.org/10.1108/MI-10-2013-0050

Publisher

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Emerald Group Publishing Limited

Copyright © 2015, Emerald Group Publishing Limited