PRINTED CIRCUIT BOARD AND EVALUATION AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To improve resistance for heat cycle by conducting analysis by specifying the electron irradiating condition using an electron micro-analyzer (EPMA) after polishing the cross section of a circuit board and then measuring the thickness of the layer indicating the particular value of the Ag strength and setting this thickness as the thickness of the Ag layer. SOLUTION: Thickness of Ag layer which is solid-dispersed to a copper circuit is set as the thickness of the layer in which Ag strength IA is in the range of 20<=IA<=40 40 by conducting the analysis, after polishing the cross section of the circuit substrate, under the condition that IPMA is used and electron irradiating condition per 1μm is 15.0kV, 1.06×10<-7> A, 30msec. The region of the Ag strength exceeding 40 includes a large amount of active metal element and the region including Ag strength under 20 does not allow solid- dispersion of Ag. Therefore, it is inadequate for this region to evaluate thickness of the Ag layer. Resistance for heat cycle of the circuit substrate can be improved depending on the value of IA. It is preferable that average thickness of Ag layer measured at the positions larger than the five positions of the circuit substrate is ranged from about. 5 to 40μm.