| 摘要 |
PURPOSE:To make it possible to form a circuit board, which is provided with via holes of a small diameter and has a large aspect ratio, without being accompanied by a disconnection of vias by a method wherein metal particles consisting of a metal having a good electrical conductivity are inserted in the via holes for raising the bottoms of the via holes. CONSTITUTION:An insulating layer 2 comprising via holes 1 is formed on an insulating substrate provided with a first conductive layer 3 and metal particles 4 are filled in the via holes 1. 'Then, after an ultrafine particle metal paste is spin coated on the layer 2, the layer 2 is heated to make the metal particles 4 in the holes 1 adhere closely to the layer 3 and at the same time, a metal film 5 is formed on the layer 2. Then, a laminated film consisting of an adhesion reinforcing metal film 6 and a conductive layer formation metal film 7 is formed on the layer 2 formed with the film 5, a resist 9 is applied on the laminated film and after that, window openings are formed at wiring pattern formation positions and conductive layer formation metal films are plated at the window opened positions in a prescribed thickness to form wirings 10. Then, after the resist 9 is removed, the film 5 on the layer 2 excluding wiring formation positions is removed by etching and a second conductive layer 14 is formed. |
