Parametric dependence of fatigue of electronic adhesives

Abstract

Adhesives used in electronic applications are subject to high cyclic shear stresses resulting from differential thermal expansion of the bonded materials.In this study, an attempt has been made to experimentally determine the dependence of the fatigue life of two packaging epoxy adhesives on: temperature, peak cycling stress as a fraction of adhesion strength, and cyclic frequency. Both epoxies were used to bond surfaces of aluminum and silicon. Tensile lap-shear specimens were used.

Chip Warpage Damage Model for ACA Film Type Electronic Packages

“…Connection deterioration mechanism for an ACF connection had not been clarified, thus, predicting life of an ACF connection was difficult [11]. To cope with these problems, there have been efforts to study the bonding quality and reliability of ACA flip-chips by conducting various environmental [1,[4][5][6][7][8][9][11][12][13][14][15][16] and mechanical tests [6,13,[17][18][19] and discussing its major failure mechanisms [6, 7, 11-13, 19, 20] and suggesting several processing control parameters [1, 3-6, 11, 12, 14, 16] to enhance the reliability.…”

Mechanical stress reduction in heat sink bond layers-a numerical feasibility study

“…As a consequence of the reduction in the stress level, the bond layer would cycle between relatively modest messes at the room temperature and the room temperature stresses. To examine the impact of this stress reduction on the bond fatigue life, equation I was utilized, with a value of 15 for the coefficient B as indicated in [3]. In this equation the room temperature stresses were used to evaluate the number of cycles to failure of the epoxy.…”

“…This pseudoexpansion coefficient was calculated according to equation 3, where AI' is the desired edge displacement of the heat sink base. ci ' = (Al'/l) I AT (3) The silicon and epoxy stresses generated during cool-down to 20C were then computed for a tri-material structure, involving a pseudoaluminum with an expansion coefficient determined by equation 3, epoxy, and silicon, all at a zero stress state of 150C First, a zero displacement constraint was applied at the edge of the plate. This run yielded the upper limit on the stresses that would develop in the aluminum plate at the curing temperature (150 C).…”

“…A recent experimental study [ 3 ] sheds light on the relationship between failure of the adhesive layer and the induced thermal stresses. This study detesmiued the dependence of the fatigue life of two epoxy adhesives on several test parameters: temperature, peak cyclic stress as a fraction of adhesion strength, and cyclic frequency, surfaces of aluminum and silicon is described in [3].…”

“…This study detesmiued the dependence of the fatigue life of two epoxy adhesives on several test parameters: temperature, peak cyclic stress as a fraction of adhesion strength, and cyclic frequency, surfaces of aluminum and silicon is described in [3]. Based on the experimental results it was found possible to develop an empirical correlation for the number of cycles to failure of such bond joints, according to equation (1) where A, B and n depend on the particular material-adhesive combination.…”