Abstract
Sintering of nanosilver paste has been extensively studied as a lead-free die-attach solution for bonding semiconductor power chips, such as the power insulated gated bipolar transistor (IGBT). However, for the traditional method of bonding IGBT chips, an external pressure of a few MPa is reported necessary for the sintering time of ~1 h. In order to shorten the processing duration time, we developed a rapid way to sinter nanosilver paste for bonding IGBT chips in less than 5 min using pulsed current. In this way, we firstly dried as-printed paste at about 100 °C to get rid of many volatile solvents because they may result in defects or voids during the out-gassing from the paste. Then, the pre-dried paste was further heated by pulse current ranging from 1.2 kA to 2.4 kA for several seconds. The whole procedure was less than 3 min and did not require any gas protection. We could obtain robust sintered joint with shear strength of 30–35 MPa for bonding 1200-V, 25-A IGBT and superior thermal properties. Static and dynamic electrical performance of the as-bonded IGBT assemblies was also characterized to verify the feasibility of this rapid sintering method. The results indicate that the electrical performance is comparable or even partially better than that of commercial IGBT modules. The microstructure evolution of the rapid sintered joints was also studied by scanning electron microscopy (SEM). This work may benefit the wide usage of nanosilver paste for rapid bonding IGBT chips in the future.
Highlights
Insulated gated bipolar transistors (IGBTs) have become important Device for power systems applications such as high-voltage direct current transmission, lamp circuit and variable speed drives, and traction [1,2]
This work may benefit the wide usage of nanosilver paste for rapid bonding IGBT chips in the future
More and more attention has been paid to using nanosilver paste in power electronic industry, especially for high temperature applications [7,8,9,10]
Summary
Insulated gated bipolar transistors (IGBTs) have become important Device for power systems applications such as high-voltage direct current transmission, lamp circuit and variable speed drives, and traction [1,2]. In order to reduce the junction temperature of silicon-based IGBT modules, more and more attention has been paid to packaging technologies and materials [4]. In order to avoid the effects of lead, people proposed many lead-free solders, i.e., Ag-Sn or Au-Sn solder [5,6]. These modules can work at the high temperature of 200 ̋ C, the short lifetime or high cost still restrict their application. More and more attention has been paid to using nanosilver paste in power electronic industry, especially for high temperature applications [7,8,9,10].
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