| 摘要 |
PURPOSE:To prevent a generation of undesirable film holes of a polyimide film and to improve a manufacturing yield of a printed wiring board made of a multilayer ceramic by filling a pore produced on a copper body (filling conductor) in a via hole with a low-viscosity polyimide at the time of a first polyimide coating on a ceramic substrate. CONSTITUTION:Ceramic green sheets in which a via hole is filled with a copper powder and also a copper paste is printed on a wiring pattern are laminated to form a layer and it is sintered so as to obtain a ceramic substrate 1. In a filling conductor 3 of said ceramic substrate 1, there is a pore (hole) 4 produced. Next, a low-viscosity photosensitive polyimide of 100 poises is dropped down to the ceramic substrate 1 for 30 sec. so as to form a polyimide layer of 1mum thick. Then, pre-baking is done. After that, a photosensitive polyimide of 4000-5500 poises is dropped onto the ceramic substrate to form a polyimide upper layer 12, followed by pre-baking. Next, a pattern covering a via hole 2 forms an insulating polyimide layer 13. |
