| 摘要 |
PURPOSE:To form a blind hole in which an excellent conductive layer can be formed by radiating the inside of a hole with a laser pulse for cleaning having relatively short oscillating time after the hole is bored to a depth at which the hole can reach copper foil below an opening with a laser pulse for boring having relative long oscillating time. CONSTITUTION:A window hole 4 is formed through the outer-layer copper foil 1 of a printed board with a drill. Then, by setting a laser pulse 5a for boring having relatively long oscillating time and another laser pulse 5b for cleaning having relatively short oscillating time, a hole 6 is formed by removing an insulating material 2 between the copper foil 1 and inner-layer copper foil 1 by radiating the material 2 with the pulse 5a through the hole 4. Finally, an epoxy resin remaining on the inner-layer copper foil 1 is removed by radiating the resin with the pulse 5b. Since no epoxy resin remains on the bottom of the hole 6, a conductive layer formed in the succeeding process can be surely connected to the inner-layer copper foil 1. |
