Date of Award

Fall 1995

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

First Advisor

Heinrich, Stephen M.

Second Advisor

Nigro, N. J.

Abstract

The differential thermal expansion of a Column Grid Array (CGA) electronic assembly results in lateral end displacements of circular solder columns. To estimate the fatigue life of a CGA assembly requires calculation of the imposed end displacement of the columns and calculation of the maximum shear strain associated with this displacement. A simple equation to estimate the thermally-induced end displacement of a column within a CGA assembly is reviewed, which assumes the columns offer negligible resistance to thermal expansion of the assembly. A dimensionless maximum shear strain/solder column end displacement relationship has been obtained using an analytical approach. The lateral force/solder column end displacement characteristics have also been obtained, for use in a more refined FEA-based displacement analysis of an entire CGA assembly where the solder column density is high and their resistance to thermal expansion of the assembly cannot be neglected. The maximum shear strain and lateral force/column end displacement analysis includes transverse shear deformation, and the displacements range from those causing fully-elastic conditions to partially-plastic conditions. These results are valid up to the end displacement at which secondary yield occurs in the columns, and the secondary yield results are included in this thesis.

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