An experimental technique for the strain measurement of small structures using pattern recognition

For an accurate measurement of the material behavior of small structures, an optical experimental technique is proposed. The test method uses a dual field of view microscope and the pattern matching algorithm. The dual field of view microscope can separately magnify the images of two adjacent regions to enhance the measurement resolution. The magnified views of the dual field of view microscope are captured by CCD cameras and the relative deformation is measured by tracing patterns in the images. A pattern matching and tracing algorithm was adapted to measure the movement of region of interests (ROI) in real time. Using the movement information of the patterns, the strain of a specimen can be obtained. This technique is non-contact as well as easy to apply to a specimen. It can be also applied in various types of specimens without any specimen preparation. Using this experimental technique, the deformation of solder joints in electronic packaging and the strain of the nickel thin film are successfully measured.