| 摘要 |
A method and material are provided for checking the location of holes drilled in copper-coated printed circuit boards. The material is a translucent, dimensionally stable plastic sheet having a blue-green or yellow-green color and a light transmissivity in the range from about 25 to 40%. The use of this particular material has been found to provide optimum contrast between a dark background created when the material overlays the copper printed circuit board, and transmitted light and light reflected from the copper surface when the holes on the printed circuit board are misaligned.
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