Thursday, April 14, 2011

US Patent 7923289 - Exothermically active nanoparticle paste

Nanoparticle materials often have a lower melting temperature than the equivalent material in bulk form due to a much higher available surface area. This patent from International Rectifier Corporation takes advantage of this property to bond electronic components at lower temperature. Claim 1 reads:

1. A process for fabricating a power semiconductor device, comprising:

disposing a mass of electrically conductive and exothermically active nanoparticle paste between an electrically conductive electrode of a semiconductor die and an electrically conductive support body;

applying energy to a portion of said mass of electrically conductive nanoparticle paste long enough to initiate an exothermic reaction to melt said mass, wherein said applying is discontinued before the completion of said exothermic reaction; and

cooling said molten mass to join said electrically conductive electrode to said electrically conductive support body.