Title :
On the effect of cure-residual stress on flip chip failure prediction
Author :
Ernst, L.J. ; Yang, D.G. ; Jansen, K.M.B. ; van´t Hof, C. ; Zhang, G.Q. ; van Driel, W.D.
Author_Institution :
Delft Univ. of Technol., Netherlands
Abstract :
Filled thermo-setting polymers are widely used as underfill- and encapsulate materials within electronic packages to improve the reliability. In the design phase, the influence of the curing of these polymers on package reliability can be judged through simulations of the curing process (including the cooling down phase) and subsequent thermal cycling. Simulations of the curing phase require an appropriate cure-constitutive model. The phenomenological model can adequately be applied for this purpose. The experimental investigation of the cure-dependent material parameters of this model was performed through intermittent Dynamic Mechanical Analyses (DMA) during the curing procedure only. It was discussed that the continuing change of material properties during cure could affect the accuracy of the model parameters thus obtained. This in turn could affect the accuracy of simulations of the curing phase in a package. In the present paper the cure-dependent material parameters, originally obtained through intermittent DMA measurements are modified using experimental data of unit-step relaxation tests being performed during cure. With the improved curing model the stress/strain state during cure of a flip chip configuration is simulated, finally leading to the residual stress- and strain fields just after cure. Subsequent cooling down and thermal cycling simulations are performed for the established residual stress/strain state as well as for an assumed "stress free" state as starting points.
Keywords :
curing; encapsulation; failure analysis; filled polymers; flip-chip devices; integrated circuit packaging; internal stresses; reliability; constitutive model; cooling down phase; curing process; dynamic mechanical analysis; electronic package; encapsulation material; filled thermosetting polymer; flip-chip failure analysis; reliability; residual stress; step relaxation; thermal cycling; underfill material; Capacitive sensors; Curing; Electronic packaging thermal management; Electronics cooling; Flip chip; Materials reliability; Phase change materials; Polymers; Residual stresses; Thermal stresses;
Conference_Titel :
Electronics Packaging Technology Conference, 2002. 4th
Print_ISBN :
0-7803-7435-5
DOI :
10.1109/EPTC.2002.1185705