AEM investigations of interphases of electrically conductive adhesive joints

For an electrically conductive joining of surface assembled components on substrates besides soft solders metal filled adhesives are used to an increasing extent. These adhesives mainly are based on epoxide resins and are filled with silver flakes of approx. 70 - 80 wt. %. The dimensions of the silver flakes are in the mym-range. Thereby a specific electrical resistance of approx. 10 high -4 Ohm cm can be achieved which is tenfold that of soft solders but acceptable f or technical application. In no case the 36-hours PC-test led to an adhesional failure of the adhesive joints. However the test occasionally caused a functional failure of the components because of excessive total resistance which could not be explained by the resistance of the chips.