Protective Layer Copper Clad Laminate for Split Through Hole Co-Planarity
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Solution Overview
Problem
The manufacturing process of multilayered printed wiring boards requires multiple lamination steps and additional plating processes, leading to increased costs and cycle times, and existing methods for forming conduction isolation portions in through holes result in plating resist adhesion and damage to the copper layer.
Innovation Solution
A copper clad laminate with a protective resin layer is used, which improves drill edge biting performance, prevents copper layer damage, and allows for easy removal of the plating resist, enabling the formation of split through holes with reduced level differences and improved co-planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lamination steps and additional plating processes are used to manufacture multilayered printed wiring boards, then the manufacturing precision and structure complexity can be achieved, but the manufacturing cost and cycle time increase
Solution Approach 1:
The through hole is segmented into multiple electrically isolated portions by introducing plating resist materials at specific locations within the through hole structure. This segmentation allows the through hole to function as multiple independent conduction isolation portions, achieving complex electrical isolation patterns without requiring multiple separate manufacturing steps for each isolation region.
Solution Approach 2:
The plating resist materials are positioned and fixed within the through holes before the actual plating process. This preliminary placement of resist materials defines the precise locations where plating will be blocked, allowing the entire multilayered structure to be manufactured in a single lamination step without subsequent adjustment or additional processing for conduction isolation.
2Manufacturing precision
If plating resist is filled into through holes to form conduction isolation portions, then electrical isolation is achieved, but plating resist adheres and remains around the opening of through holes, preventing desired wiring formation
Solution Approach 1:
The protective layer is completely removed from the surface of the copper clad laminate after the plating process. This extraction of the protective layer eliminates any residual material that would otherwise interfere with subsequent wiring formation, ensuring clean surfaces for pattern formation while maintaining the conduction isolation portions formed by the plating resist.
Solution Approach 2:
The protective layer serves as an intermediary barrier during the plating process, preventing plating resist from adhering to the copper layer surface. This intermediary layer allows the plating resist to be filled into through holes without contaminating the copper surface, and can be completely removed afterward to leave clean surfaces for wiring formation.
3Ease of manufacture
If through holes are formed by drilling to create conduction isolation portions, then the through hole structure is created, but the copper layer surface is damaged
Solution Approach 1:
The protective layer is applied to the copper clad laminate surface before drilling to form through holes. This protective layer acts as a cushioning layer that absorbs the mechanical stress and friction of the drilling process, preventing direct contact between the drill bit and the copper layer. The protective layer is subsequently removed after hole formation, leaving the copper layer intact and undamaged.
Data Source
AI summary
An object of the present invention is to provide a multilayered printed wiring board provided with split through holes excellent in through-hole formability and co-planarity in inner layer wirings around through holes for providing of a conduction isolation portion. To achieve the object, “a copper clad laminate provided with a protective layer for manufacturing of a printed wiring board having a conduction isolation portion electrically isolating a through hole, the copper clad laminate is characterized in that the copper clad laminate is provided with a protective layer on the surface that can be released after forming of the through holes for providing of a conduction isolation portion and filling of the through holes for providing of a conduction isolation portion by a plating resist” is employed.