| 摘要 |
PROBLEM TO BE SOLVED: To reduce generation of problems which are caused by the thickness of a wiring layer by performing thickness reduction process reducing the thickness of a conductor foil stuck on a base layer, and patterning the conductor foil after the above process. SOLUTION: A single-sided copper clad board is put in a state where a copper foil 3 is stuck on an insulating resin layer 2 as a base layer. A thickness reduction process reducing the thickness of the copper foil 3 is performed to the single-sided copper clad board. After that, the copper foil 3 is patterned by photoetching, and a wiring layer is formed. These layers are pressed and planarized, and a wiring board 4 is formed. In the wiring board 4, difference between a thickness T1 of an insulating layer 5 on the thin-line type wiring layer 3 and a thickness T2 of the insulating layer 5 on the solid pattern type wiring layer 3 is set to 5-6μm. Thereby generation of problems which are caused by the thickness of the wiring layer of the wiring board 4 can be reduced.
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