Multilayer printed wiring board and method for manufacturing multilayer printed wiring board

A method for manufacturing a multilayer printed wiring board, comprising:

• forming a first interlayer resin insulation layer;
• forming a first conductive circuit on the first interlayer resin insulation layer;
• forming on the first conductive circuit a coating layer which comprises a metal layer and a coating film, the metal layer being formed on a surface of the first conductive circuit, the coating film being formed on the metal layer;
• forming a second interlayer resin insulation layer on the first interlayer resin insulation layer and the first conductive circuit;
• forming an opening portion in the second interlayer resin insulation layer such that the opening portion exposes a portion of the coating layer formed on the first conductive circuit;
• removing the portion of the coating layer exposed by the opening portion of the second interlayer resin insulation layer such that the opening portion penetrates through the second interlayer resin insulation layer and the coating layer and exposes a portion of the first conductive circuit;
• forming a second conductive circuit on the second interlayer resin insulation layer;
• and
• forming a via conductor in the opening portion of the second interlayer resin insulation layer such that the via conductor penetrates through the second interlayer resin insulation layer and the coating layer and connects the first conductive circuit and the second conductive circuit,
• wherein the forming of the coating layer comprises plating Sn such that the metal layer comprising Sn plating is formed on a surface of the first conductive circuit and forming the metal layer on an entire surface of the first conductive circuit over the first interlayer resin insulation layer, and the removing of the coating layer comprises applying a permanganic acid solution to the portion of the coating layer such that the portion of the first conductive circuit is exposed and removing a resin residue resulting from the forming of the opening portion.

A method for manufacturing a multilayer printed wiring board, comprising:

• forming a first interlayer resin insulation layer;
• forming a first conductive circuit on the first interlayer resin insulation layer;
• forming on the first conductive circuit a coating layer which comprises a metal layer and a coating film, the metal layer being formed on a surface of the first conductive circuit, the coating film being formed on the metal layer;
• forming a second interlayer resin insulation layer on the first interlayer resin insulation layer and the first conductive circuit;
• forming an opening portion in the second interlayer resin insulation layer such that the opening portion exposes a portion of the coating layer formed on the first conductive circuit;
• removing the portion of the coating layer exposed by the opening portion of the second interlayer resin insulation layer such that the opening portion penetrates through the second interlayer resin insulation layer and the coating layer and exposes a portion of the first conductive circuit;
• forming a second conductive circuit on the second interlayer resin insulation layer;
• and
• forming a via conductor in the opening portion of the second interlayer resin insulation layer such that the via conductor penetrates through the second interlayer resin insulation layer and the coating layer and connects the first conductive circuit and the second conductive circuit,
• wherein the forming of the coating layer comprises plating Sn such that the metal layer comprising Sn plating is formed on a surface of the first conductive circuit, the removing of the coating layer comprises applying a permanganic acid solution to the portion of the coating layer such that the portion of the first conductive circuit is exposed and removing a resin residue resulting from the forming of the opening portion, and the forming of the via conductor comprises forming a via conductor having a bottom portion which is entirely positioned on the first conductive circuit and which is directly connected to the first conductive circuit.