Wiring substrate

A wiring substrate, comprising:

• a first wiring layer;
• an insulation layer covering a side surface of the first wiring layer and exposing at least part of an upper surface of the first wiring layer;
• and
• a second wiring layer formed on the first wiring layer that is exposed from the insulation layer, wherein
• the insulation layer includes a resin and a filler,
• the insulation layer includes an upper surface having a structure in which the filler is exposed from the resin,
• the second wiring layer includes a first metal film and a metal layer, the first metal film covering the upper surface of the insulation layer and the upper surface of the first wiring layer that is exposed from the insulation layer, and the metal layer being formed above the first metal film,
• the first metal film is formed from a CuNiTi alloy,
• a content rate of Ni in the first metal film is 5 wt % or greater and 30 wt % or less, and
• a content rate of Ti in the first metal film is 5 wt % or greater and 15 wt % or less.