Research On Vision System For MEMS Microphone Automatic Die Bonding

MEMS microphone has been widely used in Microelectronic devices due to its micro-size, resistance to interference and heat. Because of huge demand of market, MEMS microphone needs to be manufactured heavily and automatically. However, domestic MEMS microphone is assembled by operators with assistant microscope, and this manufacture style is low efficiency, poor reliability and becomes a bottleneck. So the rearch on the high-speed, high-precision and automatic MEMS placement has great significance.Firstly, aim at the MEMS chip die bonding process, the function module of MEMS placement system is analyzed, considering the technical requirement of MEMS placement system, and the function of vision system is defined, then the vision system for MEMS automatic die bonding is designed and established. At last, vision location principle is illuminated to provide a theoretical basis for the high-precision positioning.Aim at high-speed requirement of MEMS placement system, flying vision is introduced to vision system. After the analysis of typical flying vision program, a flying vision system based on the rotated reflection mirror is proposed, then some images successfully captured by the flying vision is evaluated about image sharpness by evaluation function based on image gradient, acquired experimental data shows the program is feasible.Aim at high speed and accuracy requirements of the placement, the image processing algorithms is researched. Image edge is detection robustly by self-adaptive canny algorithm; the MEMS chip position and rotated angle is calculated by Hough algorithm based on coarse-fine idea; a improved circle detection algorithm is proposed based on Hough, the circle is detected at sub-pixel accuracy by Hough and the least square circle (LSC) algorithm combination; the MEMS quality is rapidly detection by a proposed algorithm based on combined projection; at last, the algorithms proposed are tested, and high speed and precision requirements are meet.At last, the software for MEMS microphone is programmed by Visual C++, vision location and detection is tested in MEMS microphone system, the experimental result can satisfy the MEMS microphone system specifications. The successful atuo die bonding expenriment plays a positive role in MEMS microphone assembly region.