Title :
Effect of geometric surface features on void formation: application to the underfill process
Author :
Davidson, D. ; Lehmann, G.L. ; Cotts, E.J.
Author_Institution :
Dept. of Mech. Eng., State Univ. of New York, Binghamton, NY, USA
fDate :
6/24/1905 12:00:00 AM
Abstract :
A study of the capillary flow process used to place underfill material in a chip-to-substrate gap is reported. The motion of an advancing liquid front has been recorded in an experimental study on the role of geometric surface features and gap spacing characteristic of flip-chip applications. A gallery of images is presented to characterize the hydrodynamic void formation that can occur during the underfill flow process. Patterns of trace lines and solder bump cutouts have been used to construct model surfaces. The motion of the liquid front and the probability of void formation is a complex function of the surface pattern geometry. For example, at small gap spacing fluid fingers advance on trace peaks. Reconnection of finger tips creates air voids in the trough between the parallel traces. Additional examples of void formation are reported here.
Keywords :
assembling; confined flow; flip-chip devices; printed circuit manufacture; voids (solid); advancing liquid front motion; capillary flow process; chip-to-substrate gap; flip-chip applications; gap spacing characteristic; geometric surface features; hydrodynamic void formation; surface pattern geometry; underfill material placement; underfill process; void formation probability; Circuit testing; Filling; Fingers; Geometry; Glass; Hydrodynamics; Manufacturing processes; Mechanical engineering; Printed circuits; Vehicles;
Conference_Titel :
Electronic Components and Technology Conference, 2002. Proceedings. 52nd
Print_ISBN :
0-7803-7430-4
DOI :
10.1109/ECTC.2002.1008291
