Sinterconnects: All-Copper Top-Side Interconnects Based on Copper Sinter Paste for Power Module Packaging

Abstract

Copper sinter paste has been recently established as a robust die-attach material for high -power electronic packaging. This paper proposes and studies the implementation of copper sinter paste materials to create top-side interconnects, which can substitute wire bonds in power packages. Here, copper sinter paste was exploited as a fully printed interconnect and, additionally, as a copper clip-attach. The electrical and thermal performances of the copper-sinter paste interconnections (“sinterconnects”) were compared to a system with wire bonds. The results indicate comparable characteristics of the sinterconnect structures to the wire-bonded ones. Moreover, the performance of copper sinterconnects in a power module was further quantified at higher load currents via finite element analysis. It was identified that the full-area thermal and electrical contact facilitated by the planar sinterconnects can reduce ohmic losses and enhance the thermal management of the power packages.

Evaluating Cu Printed Interconnects “Sinterconnects” versus Wire Bonds for Switching Converters

“…In addition, the electrical resistance has been investigated for the "clip-attach" Sinterconnect system as a function of the thickness of the Cu-clip. As expected, since the resistance is proportional to the length of the of Cu clip and it is inversely proportional to its cross section, this analysis shows that the resistance of the "clip-attach" system can be further decreased by increasing the thickness of the Cu-clip [24].…”

“…In this study, printed Cu front-side interconnect "Sinterconnects" were benchmarked versus Al thick wire bonds as DC-DC converters. Building upon [24], this paper has carefully analyzed Sinterconnect geometries to estimate parasitic inductance parameters and measured the efficiency of a switch-mode, DC-DC converter employing Sinterconnected IGBT power modules. These Sinterconnects can easily be fabricated at any back-end (power packaging) facility by using a dispensing or jetting unit.…”

“…The graphical representation of the above-mentioned interconnects is shown in Figure 1. A detailed explanation of the manufacturing process of the Cu Sinterconnects can be found in [24].…”

“…In comparison to analytical modeling, FE analysis is able to process physical specimen details and provide high-resolution response data. It is especially suitable for considering power electronic package details in thermal domain analysis [27], as was done for the Sinterconnects in [24]. Now, in order to expand upon the results from Section 3.1, electromagnetic FE simulation has been performed.…”

“…A recent invention in this area of research uses printed Cu paste ("Sinterconnects") instead of solder paste for attaching Cu clips to a DBC substrate. Furthermore, another type of Sinterconnects was introduced by our group, in which the clip was substituted with a fully printed Cu paste [24]. It is noteworthy to mention that since the interconnects are made via sintering of the Cu paste materials, the term "Sinterconnects" were proposed to distinguish them from conventional interconnects.…”