Holographic pattern testing of printed circuit board (PCB) deformation due to thermal stress

A holographic pattern measuring system (HPMS) is used to measure the deformation of a PCB (printed circuit board) due to thermal stress. A quantitative displacement of the PCB surface can be measured by analyzing the holographic pattern. The HPMS combines holography and graphic image processing. The distribution of the microscopic displacement of the PCB surface due to thermal stress can be visualized, and a 3-D graphic image of the deformation can be obtained automatically. Experiments were carried out to the temperature on the PCB surface, the fringe pattern, and the relationship between the deformation and with the width of copper foil on the PCB through which the current flows