The correlation of shear stress and metal shift: a modeling approach [packaging]

This paper uses three dimensional finite element methods to determine the thermo-mechanically induced encapsulation stress in a 160 lead plastic quad flat pack. Comparisons are made between the effects of different leadframe materials on die stress. The degree of discretisation of the leadframe necessary to accurately model its effect on die stress is determined. A strong correlation between metal shift and out of plane shear stress is proposed following comparisons of FE package modeling and experimentally measured metal shift patterns on specially developed test die.<
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