Method for manufacturing multilayer printed circuit board

A method for manufacturing a multilayer printed circuit board, comprising the following steps:

• S1) preparing a first wiring substrate having a first insulating resin film having a first main surface and a second main surface opposite to the first main surface, a first circuit pattern formed on the first main surface, and a first protective film releasably bonded to the second main surface;
• S2) partially removing the first protective film and the first insulating resin film to form a bottomed via hole having the first circuit pattern exposed on a bottom surface;
• S3) filling the bottomed via hole with a conductive paste;
• S4) disposing a second protective film on the first protective film to cover the bottomed via hole filled with the conductive paste;
• S5) removing an unnecessary portion of the first wiring substrate after the second protective film is disposed on the first protective film;
• S6) peeling off the first protective film and the second protective film from the first wiring substrate after the unnecessary portion is removed;
• S7) preparing a second wiring substrate having a second insulating resin film having a third main surface and a fourth main surface opposite to the third main surface, and a second circuit pattern formed on the third main surface;
• and
• S8) aligning and laminating the first wiring substrate after the first protective film and the second protective film are peeled off, on the second wiring substrate so that the second main surface and the third main surface face each other, a part of the second circuit pattern is exposed through the removed portion of the unnecessary portion, and the conductive paste contacts the second circuit pattern.