Transient liquid phase sintering conductive adhesives as solder replacements

New transient liquid phase sintering conductive adhesives, which have an interpenetrating polymer/metal network, have been developed to mitigate some of the deficiencies of standard particle-filled conductive adhesives. The metal network is formed in situ by a process known as transient liquid phase sintering (TLPS) and is mutually reinforcing with the polymer network. Bulk as well as interface electrical connections are metallurgically alloyed providing stable electrical and thermal conduction. These new conductive adhesive compositions are compatible with bare copper as well as alloy finishes. The TLPS conductive adhesives utilize conventional surface mount technology dispensing and processing equipment. In testing this type of adhesive for surface mount component attach, boards were subjected to 7-foot drop tests. All components, including J-lead, gull wing and leadless, survived this test, as would be expected of typical solder joints; most traditional conductive adhesives did not. Electrical conductivity results also indicate values closer to those of traditional solder alloys. Furthermore, reliability testing including humidity followed by air-to-air thermal shock (-55 degrees C to +125 degrees C) has demonstrated that this type of adhesive performs substantially better than standard, passive filler loaded conductive adhesives.