Method for forming a via hole, flexible wiring board using the method, and method for producing the flexible wiring board
AssigneeNitto Denko Corporation
InventorsKanji Nishida, Hitoshi Ishizaka, Atsushi Hino
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Abstract
An ultraviolet beam with high energy density is applied for forming an opening in an electric conductor layer 1 in a flexible wiring board whereas an ultraviolet beam with low energy density is applied for forming an opening in an electrically insulating layer 2 in the flexible wiring board. As a result, excessive heat energy applied for forming a via hole can be reduced, so that the problems can be reduced. In this manner, high quality of the via hole and delicate and accurate processability due to use of the ultraviolet laser beam can be combined to achieve formation of fine patterns densely in the flexible wiring board.
Claims7
A method of forming a via hole in a flexible wiring board having at least two electric conductor layers and at least one electrically insulating layer for insulating said two electric conductor layers from each other, said method comprising:
- irradiating one of said electric conductor layers with a first ultraviolet laser beam;
- and
- irradiating said electrically insulating layer with a second ultraviolet laser beam;
- wherein energy density of said first ultraviolet laser beam is higher than energy density of said second ultraviolet laser beam.
Dependencies are inferred from the claim text.