Hot-stage Temperature Imaging And Alignment Accuracy Of The Bonding Process

The influence on the bonding imaging and the alignment precision of chips and substrates caused by the effects of turbulence during bonding was analyzed. By collecting a large number of images at different temperatures and adopting many different image movement computing methods with different accuracy levels, the image distortion and the image dithering rule under the influence of turbulence were analyzed. A number of valuable experimental results has been deduced which may play an important role in the improvement of alignment accuracy. This paper mainly included:1. The parameters' distribution regulation of translation, scale and rotation of sequence images at different temperatures are respectively studied by phase correlation algorithm and 6-parameter affine model hierarchical search algorithm. It was found that the most obvious motion is image dithering. At the working temperature, the error caused by turbulence can not meet the requirement of precision alignment.2.The model of image dithering based on the gray-center of image was built by two parameters of the Weibull distribution, which found that the image dithering caused by turbulence could be described by the Weibull distribution very well.3. To discover the difference affected by the turbulence between the interior regions of the chip images, we adopted the improved Lucas-Kanade optical flow method to compute the optical flow of the images.4. A set of pneumatic device was designed. By contrasting these experiments, it was found the image blurring and the integral pixel image dithering were disappeared, which can meet the requirement of precision alignment of chip and substrate and proposed a valuable reference for the technology of thermosonic flip-chip bonding.The above research provided some new ideas and possibilities for the acquisition and processing of turbulence- degraded images.