Masters Abstracts (1999)

CHENG, LINYUN
(December 1999), PhD., SUNY, Universal Instruments, Binghamton, NY

Email: bf80961@binghamton.edu

Evaluation of Underfill Materials for DCA Applications

An initial evaluation of underfill materials was performed to study their flow characteristics. Two of the encapsulants that were tested (Encapsulant D and Encapsulant G) performed the best. However, these studies were done using glass slides to simulate flow between the die and the surface of the board. This research focused on evaluating underfill materials through actual flip chip assembly. Two commercial underfill materials (Encapsulant D and Encapsulant G) were selected based upon the results obtained from initial evaluation. Encapsulant D is a conventional underfill material while Encapsulant G is a fast-flow, snap-cure underfill. The Taguchi Orthogonal Arrays (L4) method was used to study the important factors in DCA assembly. The results of this study suggest that the encapsulant type, the solder mask opening shape, and their interaction are all statistically significant at a confidence level of 95%. Hence, they are all important factors for the underfill dispensing process. During the experiments, the effects of voiding, solder mask openings, fillet shape, and filler settling were also studied. The results of the initial flow study were found to be applicable to actual flip chip assembly. Encapsulant D and Encapsulant G are good candidates for use in a contract manufacturing environment for the underfill of flip chip devices.