| 摘要 |
PURPOSE:To make the material of a resin inductive layer solventless, as a printing method for a circuit board provided with a step, so as to prevent generation of bubbles thereby preventing the withstand voltage from decreasing by forming a resin conductives layer out of thermosetting material so that it may cover the upper surface and the side face of the resin inductive layer extensively and that the ends may reach the surface of a resin insulating plate. CONSTITUTION:The hardening of a resin conductive layer is done by thermosetting, and the thermosetting temperature is in the range not exceeding Tg of a resin insulating plate and lower than Tg by 20 deg.C or less and the hardening of a resin inductive layer is done by thermosetting before hardening of the resin conductive layer, and the hardening temperature is lower than Tg of the resin insulating plate by 20 deg.C or more, and further, a second resin insulating layer is provided at the upper layer of the resin conductive layer, and the hardening is done by thermosetting. The conductive resin layer is surely printed astride the face of the resin insulating plate 1 so that the circuit-board conductor pattern 2 and the resin inductive layer may not be exposed. As a printing method for the resin inductive layer 3, stencil printing is more advantageous than screen printing since it does not engulf bubbles. As material of the resin inductive layer 3, epoxy resin is made a basis. |
