Detection Process on the Degree of Fillet Formation at Heel in the Soldered Joint of Gull Wing Type

Detection Process on the Defect in the Micro Joints by Infrared Thermal Imaging with Laser Irradiation (3rd report)

Abstract

Detection process on the degree of fillet formation at the micro soldered joints of QFP lead has been researched and developed. The shape of the joints is expressed by three parameters (fillet length, average thickness of solder, angle of flat part of lead). The fillet length can be detected by temperature of three part on the surface of lead (toe part, center part, bend part), furthermore both average thickness of solder, and angle of flat part of lead can be detected by them. This detection process is investigated by the computer simulation on thermal model of the joint of QFP between copper alloy lead with 150μm thickness and glass epoxy substrates (1.6 mm thickness).