Residual stress distribution of the soldered structure with Kovar alloy and Al2O3 ceramics

Residual stress distribution in soldered structure of Kovar alloy and Al2O3 ceramics was determined using XRD analyses. In order to measure the residual stress, position of the characteristic diffraction peak and stress constant were obtained using several versatile/advanced techniques after calibration. Residual stress of soldered structure was measured based on the diffraction patterns obtained for the distribution of residual stress in the soldered joint. Only diffraction peak at 149° for Kovar alloy and two diffraction peaks ranging from 140–170° for Al2O3 ceramics were found to be appropriate for the residual stress determination. It was also confirmed that for Al2O3 ceramics the XRD peak at 152° reflects the changes of stress more precisely than the one at 146°. The stress constant K of Kovar alloy and Al2O3 ceramics was found to be −197 MPa/° and −654 MPa/°, respectively. After soldering, the maximum residual stress of the soldered joint of both materials developed at 1 mm from the soldering seam, and the values within 3 mm from the soldering seam are generally significant. Thus, it is important to pay attention to the area of 3 mm from the soldering seam in practical application.