| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-density printed wiring board superior in surface smoothness and homogeneity at a hole wall, etc. SOLUTION: A glass fiber nonwoven fabric is used as a base material which comprises flat glass fiber by 90 wt. or more, having flatness of 3.1/1-5/1, a cross-sectional area being 90-98% of the area of the rectangle circumscribing the glass fiber cross section, and a reduced fiber diameter being 5-17μm, while the amount of binder being 3-8 wt.%. A resin composition, where the flat glass fiber powder having those characteristics is blended in a thermo-setting resin composition by 10-80 wt.%, is impregnated and dried to provide a prepreg, which is used by at least one layer, preferred as a surface layer, providing a copper-plated plate comprising a copper layer by at least one layer. At the opening of a small hole of aperture 80-150μm, a drilling assistance layer is formed on a copper foil, which is directly irradiated with high-output carbon dioxide gas laser from above to remove the copper foil, forming a through-hole and/or blind via hole. Thus, a printed wiring board is manufactured which is superior in surface smoothness, drilling characteristics with carbon dioxide gas laser, workability, and reliability in hole connection. |
