This paper provides a novel rigid composite substrate consisting of epoxy resin and hollow microspheres. Vertical curing method was applied to avoid separation of hollow microspheres from matrix resin. It was found that the substrate obtained has as low permittivity as that of polytetrafluoroethylene/glass substrate and also possesses other properties needed for printed circuit boards.

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New techniques have been developed and applied to the automatic inspection of the plated through holes of printed wiring boards (PWBs) . The new methods, called leakage light detection and self strobing, can be used to detect defects in the plating of the through holes with diametor of 0.2 mmφ and aspect ratios as large as fifteen.
The methods can detect cracks that are not revealed by a electrical conductivity tester, and can inspect any PWB without having to refer to the design data of the through hole positions. Research has shown that the smallest detectable defects is 70μm in diameter.
An inspection system was built which used these techniques. This can inspect a PWB in four minutes, and has been applied to a production line.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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