Ibiden Company Limited

Takahiro Yamashita

Kiyotaka Tsukada

Hirofumi Futamura

Hiroyuki Watanabe

Michio Ido

Morio Nakao

Akihide Ishihara

Takayoshi Katahira

There are provided a multilayer printed circuit board and a testing piece for the printed circuit board, including a substrate having an inner-layer conductor circuit and one or more outer-layer conductor circuits formed on the substrate with an insulating layer laid between the substrate and outer-layer conductor circuit, wherein a strain gauge having a resistive element held tight between resin films formed from polyimide or thermoplastic resin is buried in the substrate, and electrodes electrically connected to the resistive element are exposed to outside from the resin film and are electrically connected at exposed portions thereof to a viahole. Even if a crack is caused by an impact test to take place in the insulative resin layer, the resin film layers prevent the crack from spreading and thus the resistive element forming the strain gauge will not be ruptured. Also, not only the information on strain in the surface layer of the circuit board but also information on strain in a desired position can be measured accurately, so that an actual stress given to the circuit board can accurately be determined.

Multilayer printed wiring board and test body for printed wiring board

This invention provides a printed wiring board having an intensified drop impact resistance of a joint portion between pad and solder. An electrode pad comprises pad portion loaded with solder ball and a cylindrical portion projecting to the solder ball supporting the pad portion. An outer edge of the pad portion extends sideway from a cylindrical portion so that the outer edge is capable of bending. If the outer edge bends when stress is applied to the solder ball, stress on the outer edge of the pad portion on which stress is concentrated can be relaxed so as to intensify the joint strength between an electrode pad and solder ball.

Printed wiring board having a solder pad and a method for manufacturing the same

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Gifu, Japan

Takahiro Yamashita