Heat resistant substrate incorporated circuit wiring board

A circuit wiring board comprising:

• a wiring substrate comprising an interlayer insulating layer and a conductive layer;
• and
• a heat resistant substrate incorporated inside the wiring substrate and comprising a core substrate having a front surface and a rear surface, a plurality of through hole conductors connecting the front surface and rear surface of the core substrate, and at least one built-up wiring layer formed on the core substrate, the built-up wiring layer comprising an interlayer resin insulation layer and a conductive layer,
• wherein the through hole conductors are formed at a pitch of between 30 μm to 200 μm, wherein
• the at least one built-up wiring layer includes a front face built-up layer formed on the front surface of the core substrate and a rear face built-up layer formed on the rear surface of the core substrate, the heat resistant substrate further comprises a plurality of loading pads to be connected to an electrode of a first electronic component formed on a surface of the front face built-up layer and a plurality of connecting pads for connecting electrically an electrode of a second electronic component formed on a surface of the rear face built-up layer, and a pitch of the loading pads, a pitch of the through hole conductors, and a pitch of the connecting pads are increased in an order of the loading pads, the through hole conductors and the connecting pads.