| 摘要 |
A mask mark is irradiated by an ultra-violet light source, thereby the image of the mark is passed through a lens and a half-mirror, then reflected by a mirror, thereafter further passed through a beam splitter and a lens, forming an image on a CCD. Then the center coordinate of the image is measured by a device, next, a board mark is illuminated by an infrared light source, and its image is passed through the mirror, the half-mirror, the beam splitter, a reflector, a lens, and a beam splitter, forming an image on a CCD. The positional alignment is implemented by moving the mobile stage in the XYtheta directions based on the board mark on the infrared CCD and the mask mark on the ultra-violet CCD.
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