Acceleration measurements during reactive bonding processes

In this work, the dynamics of the bonding process using reactive multilayer systems (RMS) is studied by use of acceleration sensors. A piezoelectric accelerometer with a wide dynamic range was selected to measure the vertical acceleration during the reaction process using a Ni/Al RMS foil. This sensor was integrated into a die bonding tool. Then, bonding experiments were performed with dummy plates and substrates by igniting the RMS and measuring the sensor signal simultaneously. It was found that a strong sensor signal occurs at the time when the reaction of the RMS is completed. By additional cross sectional analysis of the bonding area, the correlation between signal height and total volume contraction has been investigated. The obtained results demonstrate that this experimental setup can be used to find materials and process conditions for bonding with significantly reduced shock-wave, lowering the risk of damage to the assembled device.