A new method using energy release elements for evaluating bonding strength [packaging]

We have developed a new method, based on the concept of energy release rate, for evaluating bonding strength. This method uses a finite element approach and places "energy release elements (EREs)" (which mathematically represent the energy release due to debonding) between the interface of two materials. The characteristic of EREs is represented by the stress-elongation relationship of the elements. This relation is defined by two parameters: maximum stress and elongation before fracture. The two parameters are determined by two measurements. By using this method, we estimated the bonding strength of photoresist patterns on Cu substrates and the debonding temperature of joints made from resin and steel. The estimated values of debonding forces and debonding temperatures closely agree with the measured ones. This close agreement shows that the new method can consistently estimate bonding strength over a wide range of shapes and load conditions.