The use of flip chip bonding technology is having a growingimportance in the construction of novel hybrid microelectronic devicesand is of increasing interest for the application in consumer orientedproducts. Especially fluxless processes are demanded for thecompatibility with underfill materials and for an improved reliabilityperformance. This paper describes the development of a fluxless flipchip mounting process by use of Au/Sn solder bumps on different thickfilm metallizations of green tape ceramic substrates. The results of theinvestigations show, that fluxless flip chip bonding is possibledirectly on Au as well as Ag and Pd/Ag thick film pattern and viametallizations. The flip chip assembly process is performed by singlechip bonding and requires substrates with narrow planarity tolerances.For the different substrate metallizations the range of optimal bondingparameters are determined. Best mechanical and electrical results areachieved with Au/Sn bumps on Pd/Ag thick film metallizations. For thissystem the investigations are performed, to show the influence of thechip size and bump height on reliability. The fatigue life of solderjoints, which is limited by the thermal expansion mismatch between chipand substrate could be significantly increased by an adequateencapsulation process. The reliability results of the fluxless flip chipjoints after thermal cycling, temperature storage, temperature-humidityand pressure cooker tests are presented
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