Process for producing wiring substrate

[0180]In a case where the wiring substrate 1 is produced by the process (i), a laminate 1A having a layer structure of first conductor layer 12 / layer (A) 10 / second conductor layer 14 / adhesive layer 16 / layer (B) 18 as shown in FIG. 1A is used. As shown in FIG. 1B, a hole 20 which penetrates from the first conductor layer 12 through the layer (B) 18 is formed in the laminate 1A e.g. by a drill or laser. Then, either one or both of a treatment with a permanganic acid solution and a plasma treatment is applied to an inner wall surface 20a of the hole 20 formed without conducting an etching treatment using metal sodium, and then as shown in FIG. 1C, e.g. electroless plating is applied to the inner wall surface 20a of the hole 20 to form a plating layer 22.

[0181]In a case where a wiring substrate 2 is produced by the process (i), a laminate 2A having a layer structure of first conductor layer 12 / layer (A) 10 / second conductor layer 14 / adhesive layer 16 / third conductor layer 24 / layer (B) 18 / fourth conductor layer 26, as shown in FIG. 2A, is used. In the same manner as in the case of the wiring substrate 1, as shown in FIG. 2B, a hole 20 which penetrates from the first conductor layer 12 through the fourth conductor layer 26 is formed in the laminate 2A. Then, either one or both of a treatment with a permanganic acid solution and a plasma treatment is applied to an inner wall surface 20a of the hole 20 formed without conducting an etching treatment using metal sodium, and then as shown in FIG. 2C, a plating layer 22 is formed on the inner wall surface 20a of the hole 20.

[0182]In a case where a wiring substrate 3 is produced by the process (i), a laminate 3A having a layer structure of first conductor layer 12 / layer (A) 10 / layer (B) 18 / second conductor layer 14, as shown in FIG. 3A, is used. In the same manner as in the case of the wiring substrate 1, as shown in FIG. 3B, a hole 20 which penetrates from the first conductor layer 12 through the second conductor layer 14 is formed in the laminate 2A. Then, either one or both of a treatment with a permanganic acid solution and a plasma treatment is applied to an inner wall surface 20a of the hole 20 formed without conducting an etching treatment using metal sodium, and then as shown in FIG. 3C, a plating layer 22 is formed on the inner wall surface of the hole 20.