Characterizations of Rapid Sintered Nanosilver Joint for Attaching Power Chips

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.

Three‐dimensional damage morphologies of thermomechanically deformed sintered nanosilver die attachments for power electronics modules

“…Although the use of this X-ray CT has been prevalent within other scientific fields for a number of decades, its emergence within power electronics packaging reliability studies is relatively recent (Xiao et al, 2011;Padilla et al, 2012;Agyakwa et al, 2014;Li et al, 2014;Agyakwa et al, 2016;Feng et al, 2016;Regalado et al, 2019). There are a number of reasons for this.…”

Recent Progress in Rapid Sintering of Nanosilver for Electronics Applications

“…Therefore, new processes need to be developed to shorten the sintering time, simplify the sintering process, and improve the sintering properties of the joints. Recently, extensive studies on the rapid sintering processes for nanosilver have been carried out [ 34 , 115 , 116 , 117 ]. Processes such as discharge plasma assisted sintering, laser sintering, and current assisted sintering cannot only enhance the efficiency of sintering, but also improve the properties of the sintered joints.…”

Does plasma jet sintering follow an Arrhenius‐type expression?

“…Traditional sintering methods rely on a combination of high temperature, high pressure, or fast energy deposition requiring well‐isolated furnaces, robust pressurizing strokes, or collimated lasers. [ 11–15 ] New methods are required to meet electrical, thermal, and mechanical property requirements, while also being compatible with roll‐to‐roll and high‐throughput additive manufacturing. [ 16 ] Atmospheric pressure, ambient temperature nonthermal plasmas can effectively deliver energetic plasma species, including electrons and ions, to a surface and have recently emerged as an alternative to conventional sintering methods.…”