Assembly of planar array components using anisotropic conducting adhesives-a benchmark study: pt.I. Experiment

This paper presents new results from an experimental and theoretical program to evaluate relevant process parameters in the assembly of a 500 μm pitch area array component using anisotropic conductive adhesive (ACA) materials. This experimental configuration has features of micro ball grid array (μBGA), chip scale packaging (CSP), and also flip-chip and conventional ball grid array (BGA) package structures. A range of materials combinations have been evaluated, including (random filled) adhesive materials based on both thermoplastic and thermosetting resin systems, combined with both organic and thick-film on ceramic substrate materials. The ACAs used have all been applied as films, and hence are also known as anisotropic conducting films (ACF). The test assemblies have been constructed using a specially developed instrumented assembly system which allows the measurement of the process temperatures and pressures and the consequent bondline thickness reduction and conductivity development. The effects of the process parameters on the resulting properties, particularly conductivity and yield, are reported, A complementary paper indicates the results of computational fluid dynamics (CFD) models of the early stages of the assembly process which allow the extrapolation of the present results to finer pitch geometries