Building a Delamination-free Electronic Package Using Thermal Analysis Data

Package delamination is a product of chemical, mechanical and thermal incompatibilities. Thermal analysis methods are used to study these factors along with other techniques. One thermomechanical analysis (TMA) data that can be maximized in order to get a delamination-free combination of materials is the glass transition temperature (Tg) measurement. The thermograph produced contains information on Tg, coefficient of thermal expansion (CTE) and total expansion (dimension change). The technique shown in this paper is to combine different Tg thermographs of adhesives, encapsulants and metal parts in order to create a “package”. To keep the unit from “delaminating”, the thermographs have to be as uniform as possible when overlayed. At the very least, the graphs should be able to show which interfaces are at risk of delamination during certain assembly processes. The same concept is used if one intends to improve an existing process condition. Thermographs of copper leadframe (Cu LF), die attach (DA) adhesive and epoxy mold compound (EMC) samples are generated using cure profiles (for the polymers only) and a standard heating rate of 10°C/min. The resulting thermographs are overlayed and the best combination is chosen by visual comparison. The beauty of the technique is that it is simple, rich in technical basis and individual results can be easily stored in a database.