Method of manufacturing multilayer printed wiring board

A method of manufacturing a multilayer printed wiring board including an internal wiring circuit formed on a board, an insulating resin layer formed on the internal wiring circuit, a blind hole formed in the insulating resin layer and communicating with the internal wiring circuit, and a conductive portion formed on an inner wall of the blind hole and connected to the internal wiring circuit, the method comprising the steps of:

• forming the blind hole by using a short-pulse CO.sub.2 laser;
• preparing at least two internal wiring circuits which are isolated from each other by an insulating layer in a direction of thickness;
• forming one land portion, which has a hole formed in correspondence with the blind hole, on one of the two internal wiring circuits which is on an upper surface side;
• forming the other land portion on the other internal wiring circuit on a lower surface side in correspondence with a bottom portion of the blind hole so as to have a diameter larger than that of the hole of said one land portion;
• forming the blind hole by using a laser beam from a short-pulse CO.sub.2 laser which has a diameter smaller than the diameters of the two land portions and larger than the diameter of the hole of said one land portion;
• and,
• performing through hole plating.