| 摘要 |
PROBLEM TO BE SOLVED: To provide a printed wiring board having less dispersion of interlayer insulating resin thickness, which becomes a problem, and having an insulating layer without glass cloth. SOLUTION: In a build-up material for multilayer wiring board, two or more types of insulating resin components different in molecular weights are mixed, so that heat time flow property becomes different, and the component whose mixing ratio is changed is coated on a carrier film as the insulating resin layers of two or above layers. The softening point of at least one layer in the insulating resin layer of two or above layers is 50 deg.C to 90 deg.C, projecting and recessing parts such as the wiring circuit of a core substrate laminated at the time of press-laminating are filled with materials and inter-insulating layer thickness is secured to be constant and it can be smoothed. |
