Blind Via Hole in Multi-layer AFRP Printed Wiring Boards by Build Up Process. Quality of Drilled Hole by Small Power Laser.

Abstract

In the printed wiring board manufacturing sector, methods are developed to improve the circuit packaging density. The multi-layer printed wiring board manufacturing process is receiving particular attension. In the current manufacture of these boards, the method frequently used is to laminate the core with insulating resin. Photo-etching is generally used to form the holes connecting the circuits of these boards. However, a problem has emerged in that the strength of the substrate decreases due to the insulating resin part as the multi-layers are progressively formed. Thus, it becomes necessary to use FRP for the insulation layer part. Since it is very difficult to etch composites, lasers have been proposed for a new way to drill holes in such materials. By appropriate adjustment of the laser panetration energy, the holes are drilled only in the insulation part, and a technique is proposed to stop the holes using the copper foil forming the circuit. AFRP has been considered a suitable FRP for such laser processing. In the present study, attempts were made to experimentally produce multi-layer boards using AFRP and GFRP for the insulation layer, and the characteristics of blind via holes drilling with a small power laser were investigated.