Die bonding in embedded substrates

In advanced packaging processes the chips are molded after placement and the chip bonding pads need to be opened by laser drilling. In order to avoid post bond measurements and any correction of individual drilling location it is important to establish a process of high precision die bonding. We investigated the die bonding of 50 μm thin silicon chips on Cu leadframe using thin layers of Au/Sn solder and studied the assembly with respect to solder joint formation, metallurgy, mechanical strength and finally the post bond accuracy achieved.