Propensity of Copper Dendrite Growth on Subassembly Package Components Used in Quad Flat Package

Abstract

Cu dendrite growth of quad flat package linked to epoxy molding compound (EMC), leadframe, and leadframe adhesive tape is comprehensively investigated. Cu dendrite grows particularly in the lead pitch smaller than ≤ 130 µm covering with a leadframe tape, and in turn, it results in a resistive short. Such an appearance is attributed to test procedure of the precondition (30 • C/60% relative humidity with 260-• C reflow) followed by biased stress test (125 • C/1.95 V), which not only allows moisture condensation in the tape and but also provides bias between the leads. The influences of impurity in EMC and adhesive tape on dendrite formation are quantified with SEM-EDX, Auger electron spectrometry (AES), inductively coupled plasma-mass spectrometry (ICP-MS), and ICP-AES. As a result, the usage of nonhalide EMC can provide more reliable margin than that of larger lead spacing against Cu dendrite growth.Index Terms-Cu migration, dendrite, epoxy molding compound (EMC), high-temperature operating life (HTOL) test, leadframe, leadframe tape, precondition, quad flat package (QFP).