Wiring substrate

A wiring substrate, comprising:

• a first insulating layer;
• a conductor layer formed on the first insulating layer and including a wiring pattern;
• an organic coating film formed on the conductor layer such that the organic coating film is formed on the wiring pattern of the conductor layer and covering a side surface of the wiring pattern;
• and
• a second insulating layer formed on the first insulating layer such that the second insulating layer is covering the conductor layer,
• wherein the organic coating film is formed such that a root mean square height of the surface of the organic coating film is in a range of 0.010 μm to 0.100 μm, the conductor layer is formed such that the wiring pattern has a polished surface on an opposite side with respect to the first insulating layer and includes a first wiring and a second wiring formed adjacent to the first wiring, that each of the first wiring and the second wiring has a wiring width of 5 μm or less, and that a distance between the first wiring and the second wiring is 7 μm or less, the organic coating film is formed on the wiring pattern of the conductor layer such that the organic coating film is covering the polished surface of the wiring pattern, and the conductor layer includes a seed layer formed on the first insulating layer, and an electrolytic plating film formed on the seed layer such that the conductor layer is formed by forming a plating resist formed on the seed layer, forming on the seed layer exposed from the plating resist the electrolytic plating film having a thickness larger than a thickness of the plating resist, and reducing the thickness of the electrolytic plating film and the thickness of the plating resist by polishing.