The evaluation of flowability and wire sweep by epoxy molding compound for power module packages using Moldflow™

Abstract

Customers demand various functions from their applications and, in order to satisfy these demands, module packages must be multifunctional. This applies to power module packages that include power devices, components and control ICs. The modules must also have substrates in order dissipate heat from operating power chips as well as a PCB to create multifunctional circuits. Occasionally, specific clips are used instead of wire interconnections and the inner structures of the power module packages become complicated by a customer's design requests. When those power module packages accept epoxy molding compound (EMC), it may become difficult to achieve good `flowability,' perfect molded packages, and stable wire sweep index and it may also be hard to avoid wire sagging risk. Finite element analysis (FEA) for semiconductor encapsulation early in the design phase is now essential to finding out target designs and proper quality of flow. FEA also helps to recommend proper runner systems, gate design, and the number of gates, which also helps to save time and money when producing the initial mold die. This paper will compare and discuss the limitations of the flow pattern, wire sweep, air vent effect, and air trap between the result of commercial FEA software, Moldflow™ and the real samples.