Optimal Detection Condition and Minimum Defect Size for Detection by Computer Simulation

Detection Process on the Defect in the Micro Joints by Infrared Thermal Imaging with Laser Irradiation (2nd report)

Abstract

The position and size of internal defect, optimal detection condition and minimum defect size on the inspection are investigated on the computer simulation on thermal model of the joint.
The size and position of internal defect can be determined by the area of temperature above T_c on the joint surface, and then optimal detection condition (laser power, taking time of thermal image) are decided by the relation between temperature behavior of the joint under laser irradiation and characteristics of thermography.
Furthermore, minimum defect size on the inspection is influenced by kinds, thickness of the lead and thermal transfer coefficient at the interface of the joint, and is nearly 50, urn in the case of the micro joint between cepper alloy lead with 150μm thickness and glass epoxy substrates (1.6 mm thickness).