| 摘要 |
PROBLEM TO BE SOLVED: To ensure void free adherence between an insulation layer of resin sheet and an underlying conductor layer by setting the viscosity of a resin material on one side at a first value insusceptible to deformation through press and the viscosity of a resin material on the other side at a second value susceptible to deformation through press. SOLUTION: First and second resin layers 12, 13 are formed sequentially on one side of a copper toil 11. The first resin layers 12 is formed of a thermosetting resin, e.g. epoxy resin or polyimide, exhibiting fluidity insusceptible to deformation through press under normal conditions while the second resin layers 13 is formed of a thermosetting resin exhibiting fluidity susceptible to deformation through press under normal conditions. At the time of hot press to an inner layer board 4, void free adherence can be ensured between the resin material forming the second resin layers 13 and the inner layer board 4 while keeping the distance between conductor layers 2, 3 and the copper foil 11 through the first resin layers 12 in a resin coated copper foil 10. |
