Thermal fatigue life assessment method and that device null of the oolder joint

摘要

PROBLEM TO BE SOLVED: To nondestructively estimate the thermal fatigue life of a solder weld part with high precision.;SOLUTION: This method comprises a process 12 for preliminarily determining a plastic strain (Δεp) resulted from a repeated thermal stress generated in a solder connection part 3 of an electric circuit by a finite element two-dimensional elastoplastic analysis; a process 18 for determining a crack extension rate equation showing the relation between a crack extension rate (da/dn) determined by observing the solder weld part after executing a temperature cycle test for the electric circuit and the plastic strain (Δεp); a process 20 for determining a life evaluation reference equation showing the relation among the plastic strain, the crack extension rate, the joint length of the solder weld part, and the life cycle number to penetration; and a process 20 for determining the life cycle number of a designated diagnostic object, corresponding to the joint length of the solder weld part of the electric circuit by use of the life evaluation reference equation.;COPYRIGHT: (C)2005,JPO&NCIPI