Noise Diagnostics of Climatically Treated Joints Formed from Conductive Adhesive

The noise measurement was used for monitoring the changes of the joints made from electrically conductive adhesive caused by mechanical and climatic treatment. A total of five types of isotropic adhesives were tested. Three types were from one and two from another manufacturer. Four types were based on a bis-phenol epoxy matrix and one type on an acrylate resin. All were filled with silver flakes. The concentration of the filler was in the range of 65 – 75 wt %. Joints loaded with the mechanical stress and joints without this load were aged at the temperature of 120 °C and the RH 64 % for 1000 hours. The total time of heat treatment was divided into five stages. The relative changes in the noise voltage between stages were monitored. It was found that the mechanical load accelerates the changes caused by climatic treatment of the joints and that some adhesives were not fully cured.