Wiring substrate

A wiring substrate, comprising:

• a core substrate;
• and a build-up part formed on the core substrate and comprising a plurality of insulating layers and a plurality of conductor layers, wherein the plurality of conductor layers includes at least one conductor layer having a first wiring and a second wiring such that the second wiring has a conductor thickness smaller than a conductor thickness of the first wiring and that a minimum value of a line width of a wiring pattern of the second wiring is smaller than a minimum value of a line width of a wiring pattern of the first wiring, A wiring substrate, comprising:
• a core substrate;
• and a build-up part formed on the core substrate and comprising a plurality of insulating layers and a plurality of conductor layers, wherein the plurality of conductor layers includes at least one conductor layer having a first wiring and a second wiring such that the second wiring has a conductor thickness smaller than a conductor thickness of the first wiring and that a minimum value of a line width of a wiring pattern of the second wiring is smaller than a minimum value of a line width of a wiring pattern of the first wiring, the plurality of conductor layers includes a plurality of conductor layers each having the first wiring and the second wiring, and the plurality of insulating layers in the build-up part includes a plurality of insulating layers each having a dielectric loss tangent of 0.005 or less and a relative permittivity of 3.5 or less at a frequency of 1 GHz such that the conductor layers having the first wiring and the second wiring are formed on surfaces of the insulating layers having the dielectric loss tangent and the relative permittivity, respectively.