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Flip-chip-on-board (FCOB) assembly and reliability

This paper discusses the methods of direct chip attachment (DCA) and the results of interconnect reliability qualification of flip chip assemblies with underfill. The method developed provides a 'dropin' surface mount process to attach bumped silicon devices to laminates utilizing standard surface mount assembly equipment. Assemblies of test vehicles and product modules demonstrated satisfactory results in all of the reliability qualification and product conformance criteria. Results of failure mode analysis (FMA) of assemblies subjected to thermal stress are discussed.