EXPERIMENTAL INVESTIGATION OF THE FORMATION OF SURFACE-MOUNT SOLDER JOINTS

As part of a major project to develop a computer-based model to suppor t the product and process design activity for reflow soldered assembli es, it has been found necessary to carry out fundamental investigation s of the processes occurring as solder pastes approach and pass the re flow temperature. This paper presents the results and our interpretati on of the observed physical phenomena arising from recent high-speed v ideo microscopy studies of the reflow of bulk deposits of solder paste and also of the formation of solder joints during infrared reflow sol dering. These studies have provided insights into the physical phenome nology of reflowing solder paste, the interpretation of wetting curves and the mechanisms behind the formation of manufacturing driven defec ts.