Wiring board

A first substrate (10), a surface conductor layer (12), and a second substrate (20) of the wiring substrate are laminated in this order. The second substrate (20) uses an organic material as an insulating base material. The surface conductor layer (12) is located on the surface of the first substrate (20), and the second substrate (20) has a plurality of interlayer connection conductors (22). The insulating base material of the second substrate (20) has a first region (211) and a second region (212). The first region (211) is located on the surface conductor layer. The second region (212) is located on the surface of the first substrate. The first region (211) has a smaller ratio of voids and pores than the second region (212). 布线基板的第1基板(10)、表面导体层(12)和第2基板(20)被依次层叠。第2基板(20)将有机材料作为绝缘基材。表面导体层(12)位于第1基板(20)的表面上，第2基板(20)具有多个层间连接导体(22)。第2基板(20)的绝缘基材具有第1区域(211)和第2区域(212)。第1区域(211)位于表面导体层上。第2区域(212)位于第1基板的表面上。第1区域(211)与第2区域(212)相比而空洞、气孔的比例更少。