The heat expansion of the solder joint on a PCB board has been investigated using speckle interferometry. Set-ups for measuring in-plane and out-of-plane displacements have been separately used. The component was stepwise heated by increasing the working current. During the heating the temperature was measured by a thermocouple. For each step, the heating was halted until thermal equilibrium occurred, then four phase-shifted interferograms were recorded for each temperature T$-n$/. In this way the deformation between two temperatures T$-n$PLU@1$/ and T$-n$/ were evaluated. The deformation was measured in different directions and the joint solder's strains were calculated.
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