Chemical and physical characterization techniques in highlighting intermetallic compound (IMC) formation

Abstract

Evaluations and qualifications on ball attach process for bump packages, studies on solderability between lead to PCB on leaded packages, wire bond integrity evaluations, these are studies that involves thorough characterization on bonds and intermetallic compound (IMC) layers for different interfaces. For ball attach process in bumped packages, we focus on intermetallic formation between solder ball to the under bump metal (UBM). For solder integrity, studies focus on the lead post to solder to PCB interface. Intermetallic Compound (IMC) formations between interfaces, is valuable in characterizations. The formation of intermetallics not just cause good integrity on the interface or bond, but can also cause assembly related problems. Example, intermetallics of gold and aluminum are a significant cause of wire bond failures in semiconductor devices and other microelectronic devices. In analyzing intermetallic compound formations, there is a need for the IMC layer to be highlighted, for interface layer difference, for measurement on the thickness, and to merely highlight. This paper aims to present a study on the manual techniques in highlighting intermetallics. Chemical etching, delayering, and immersion on chemical solutions, done on different types of samples to highlight intermetallic compound (IMC).