Thin die bonding techniques

Picking and bonding 50-micron thick chips presents new challenges to the die bonder industry. Extensive development efforts have identified a number of process challenges and solutions. This paper summarizes Esec\´s most recent learning\´s pertaining to the thin die bonding process. Problems with standard die bonding chip pick up and epoxy-dispensing techniques are discussed and solutions identified. Two novel pick solutions for thin die applications are also presented. The pick process is actually composed of two separate actions, peeling the foil from the chip and picking the chip from above with a vacuum tool. A "peel first, pick second" method for separating chips from the wafer is presented, however, newly developed die attach films applied directly to the backside of the wafer are shown to increase the adhesion of the foil to the chip, hindering this peeling process. A second process, utilizing a ramp to assist the peeling process, is also presented. This method offers the benefits of low cycle time; extreme thin die capability and a more robust peeling process, which is capable of handling the increased adhesion of the die attach films.