| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit forming substrate which does not contain a harmful substance such as halogen and has superior adhesive strength, heat resistance, and fire resistance as a circuit forming substrate having metal foils on both its surfaces. SOLUTION: Desired characteristics are obtained by incorporating 3 to 30 wt.% nitrogen, phosphor us or silicon in the impregnated resin structure of a porous base material 41 for a circuit board obtained by connecting metal foils 45 with conductivity by conductive compositions 44 charged in through holes 43 bored in the porous base material 41, compressing the porous base material, and making the conductive compositions dense. |
