The electrode pad 4 includes a base layer and a coat layer. The base layer is made of metal such as W, Mo, Mn, Cu, Ag, and alloy of these metals. The coat layer is made of metal such as nickel (Ni) and gold (Au). For example, the electrode pad 4 may be formed by coating an electrode of Cu with Ni and Au.

The through holes 4A can be formed by semi-additive method, for example. This is specifically implemented by: applying masks corresponding to the through holes 4A onto the base layer of the electrode pad 4; forming the coat layer on the base layer by plating; and removing portions of the base layer which correspond to the through holes 4A, by etching.

The wiring board 1 according to the above embodiment serves to produce the following beneficial effects.

(1a) The electrode pad 4 including the through holes 4A allows the gas produced by the vaporization of residue in the void V, to be discharged via one of the through holes 4A overlapping with the void V. This serves to suppress the electrode pad 4 from undergoing the bulge through the heating process, and thereby improve the wiring board 1 in reliability of connection involving the electrode pad 4.

(1b) The electrode pad 4 including the central part 41 and the peripheral part 42 serves to suppress the bulge from occurring in the central part 41 contributing to the connection between the electrode pad 4 and the conductor 3, and simultaneously improve the electrode pad 4 in strength of joint with the insulator layer 21 in the peripheral part 42.

[Other Embodiments] The present disclosure is not limited to the embodiment described above, but may be implemented by various embodiments.