Stress Singularities and Discontinuities on the Free Surface of a Thermo-Elastoplastic Bimaterial Body

1990 ◽  
pp. 36-45
Author(s):  
H. D. Bui ◽  
S. Taheri
Keyword(s):  
Free Surface ◽  
Stress Singularities

Stress singularities at the free surface of an axisymmetric two-material creep test specimen

1997 ◽  
Vol 32 (2) ◽  
pp. 107-117 ◽  
Author(s):  
T H Hyde ◽  
W Sun
Keyword(s):  
Free Surface ◽  
Steady State ◽  
Creep Test ◽  
Test Specimen ◽  
Stress Singularity ◽  
Finite Element Analyses ◽  
Stress Singularities ◽  
Material Creep ◽  
Power Law Creep ◽  
Relative Creep

The nature of the stress singularity that occurs at the surface of an axisymmetric, two-material creep test specimen has been investigated. Steady state finite element analyses were obtained for this purpose, using Norton's power law creep equations having the same stress exponent for each material. The strength of the singularity was found to be strongly dependent upon the relative creep strengths of the two materials, but was surprisingly insensitive to the relative dimensions of the two materials. The implications of the results for practical situations are discussed.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

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