FINITE ELEMENT ANALYSIS FOR TRANSIENT THERMAL CHARACTERISTICS OF DIE-ATTACH ADHESIVE GRAPHENE CONDUCTIVE PASTE

Abstract

With the increase of operating temperature of high-temperature power electronics applications, a new requirement has emerged, which requires appropriate materials that meet the new specifications. In this context, the die-attach layer (attached substance between the semiconductor device and substrate) is one of the most significant components of power electronics modules, and choosing the right die-attach material is one of the most difficult challenges. Using transient thermal analysis, this study determines the best die-attach materials for conductive ink performance in thermal conductivity. It was carried out with the use of finite element analysis (FEA) modelling approaches. For FEA analysis, four different die-attach materials of conductive ink straight line patterns were developed: Au/Sn (80/20) braze, nanoscale silver, SAC alloy solder paste, and Epo-Tek P1011 epoxy. By evaluating the maximum temperature and total heat flux, FEA modelling can be utilised to identify which die-attach materials have more effect on thermal conductivity to the graphene conductive ink circuits on copper substrate. For the varying die-attach materials’ effect of thermal conductivity, a modelling approach of conductive ink patterns with silicon carbide (SiC) diodes attached to the directly bonded graphene with die-attach materials was proposed to be used. The temperature and total heat flux time-dependent during heating within 1.5 s was optimised by using temperature load of 90.3 °C on the dies (diode) in the circuit. The epoxy achieved the best results in terms of the least maximum temperature and total heat flux with the values of 90.3 °C and 0.8073 x 107 W/m2 respectively. As a result, epoxy types of die-attach materials have the best potential to be effective heat conductors. This is due to the results that epoxy die-attach materials have the highest thermal resistance and lowest thermal conductivity.
Keywords: Die-attach materials; graphene conductive inks; finite element analysis (FEA); transient thermal; thermal conductivity.

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