A Novel Flip Chip Bonding Technology Using Au Stud Bump And Lead-Free Solder

摘要

A cost-effective Au-solder flip-chip bonding technology working with unique designs of bondign pads and solder resist on organic substrate has been developed. The increasing demand for smaller and lighter system module, and the design requirements for electrical and thermal enhancement drive the deployment of flip chip technologies. Existing flip chip technologies are briefly reviewed and compared; the key design techniques and solder selection to drive the process improvement are explained in details the process improvements include: 1. Excellent void control over underfill resin; 2. Formation of uniform solder humps on the bonding pads of the substrate; 3. Selection of non-lead solder to enhance interconnection reliability. An 5-chip MCM design example is shown for the improvement of bonding time; a test vehicle used for reliability tests is described, the result of reliability tests confirms Au-solder flip chip bonding technique is a sound bonding process.