| 摘要 |
PURPOSE:To improve reliability of a multilayer printed circuit board by irradiating a processing surface separated by 0.1mm or larger from a mask with a laser beam, using the mirror mask of dielectric material selectively forming dielectric multilayer film on a substrate. CONSTITUTION:In a multilayer printed circuit board, an insulating film 22 and a wiring layer 23 are alternately laminated on a substrate 21 and a wiring layer 23 is alternately connected through via holes 24 formed on the insulating film 22. Here, the via holes 24 are formed as described below. A dielectric material mirror mask 7 selectively forming a dielectric material multilayer film 5 on a transparent substrate 1 is fixed on the insulating film 22 formed on the substrate 21 with separation of at least 0.1mm or larger. This mirror mask is irradiated with parallel laser beam for the purpose of abrasion of the insulating film 22. The abrasion is conducted for the entire region of the insulating film 22 while the dielectric material mirror mask 7 and the substrate 21 are moved simultaneously to form via holes on the insulating film 22. Thereby, reliability of multilayer printed circuit board can be improved. |
