| 摘要 |
PURPOSE:To improve the reliability of a printed board, by examining the soldered state of a deep part of an highly integrated IC package, which is mounted on the printed board, by the combination of lighting from the back surface of the printed board and an optical system having a long focal depth. CONSTITUTION:An inspecting apparatus is composed of the following parts: a printed board 2, on which an IC package 1 is mounted; a lighting device 4, which projects light into a narrow gap between the package 1 and the board 2 uniformly through the semi-transparent board 2 from the back side of the printed board 2; a reflecting prism 5, which bends the light from the IC upward at a right angle; and a microscope 6, having a long focal depth. At the time of inspection, the light is projected from the back surface of the board 2. A part of the light is transmitted and another part is diffused. Then a soldered part is uniformly lighted. The transmitted light is bent upward at a right angle by the prism 5, which is provided at the close proximity of the side surface of the package 1. The inspection is performed by a microscope 6. The microscope 6 is composed of an object lens 12 and a small stop 13. A part of the board 2 is lighted as the diffused surface. Therefore, the boundary between the board 2 and the solder fillet can be clearly observed.
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