Hitachi Techno Engineering Co., Ltd.

Masami Iwakura

Akimi Miyashita

Mutsumasa Fujii

Kenichi Takahashi

Makoto Kato

In a hot press according to the present invention, a control panel detects the fact that the viscosity of bonding resin of multilayer circuit board materials is minimized by taking thereinto at least one of the values measured by a speed sensor of a lower bolster, a measuring portion for measuring a control current of an electromagnetic proportional relief valve and a relief amount detector for detecting the relief amount of the electromagnetic proportional relief valve, and gives an instruction of an optimum air pressure addition timing. Accordingly, even if the multilayer circuit board materials and the like are varied, it is always possible to change over from a vacuum condition to an air pressure added condition at the best timing, thereby making it possible to obtain a multilayer circuit board of a uniform thickness without causing generation of void.

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Shimodate, Japan

Masami Iwakura