| 摘要 |
PROBLEM TO BE SOLVED: To prevent decreasing of the adhesion strength of an insulation layer formed with an insulation film layer on a board to form a multilayer wiring board in a heating process. SOLUTION: The multilayer wiring board has a plurality of organic resin insulation film layers 4 and wiring conductor layers 3 laminated into a multilayer on a board 1 and an overcoat layer 6, formed, extending from the exposed surfaces of the insulation film layers 4 to the board 1 surface. The overcoat layer 6 has a steam permeability of 5 g/(m2.24 h) and the board 1 has a surface roughness (Ra) set in a range of 0.05-10μm at the surface contacted to the overcoat layer 6. This reduces the moisture absorption of the insulation film layers 4, to thereby eliminate the swell of these layers 4 and hence avoid lowering the adhesion strength of the insulation layer. |
