Development of solderless joining technologies using conductive adhesives

A solderless joining technique using a new Ni-type conductive adhesive was developed. First, the electrical performance was evaluated using a practical module. The delay time and output voltage of a hybrid IC (HIC) module assembled using the conductive adhesive were equivalent to that using standard eutectic solder. Secondly, the joining reliability was examined using an area array package. No electromigration was observed at any joint in the temperature-humidity bias (THB) test (85/spl deg/C, 85%RH, DC 5 V, 1000 hr). A ceramic chip scale package (CSP-C) mounted on an FR-4 motherboard using this conductive adhesive showed 5 times longer lifetime than that using standard eutectic solder in temperature cycling tests (-40 to 125/spl deg/C). Additional lifetime extension was attained through change in the packaging structure.