A material of the insulating layers 17 is not particularly limited. For example, an insulating material such as a thermosetting resin such as an epoxy resin, a thermoplastic resin such as a polyimide resin, or a resin in which the thermosetting resin or the thermoplastic resin is impregnated in a core material such as a glass fiber (glass cloth or glass fabric) along with an inorganic filler, such as prepreg, an Ajinomoto build-up film (ABF), FR-4, bismaleimide triazine (BT), or the like, may be used for the insulating layers 17.

The wiring layers 16 may be electrically connected to the electronic device 1, which will be described below.

A conductive material such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), or alloys of Al, Ag, Sn, Au, Ni, Pb, and Ti, may be used as a material of the wiring layers 16.

Interlayer connection conductors 15 for connecting the layered wiring layers 16 to each other may be disposed in the insulating layer 17.

Further, an insulating protective layer may be disposed on a surface of the substrate 10. The insulating protective layer may be formed of solder resist and may be disposed to cover both an upper surface of an uppermost insulating layer 17 and a lower surface of a lowermost insulating layer 17, such that the insulating protective layer may protect an uppermost wiring layer 16 disposed on the upper surface of the uppermost insulating layer 17 and a lowermost wiring layer 16 disposed on the lower surface of the lowermost insulating layer.