Wiring Board Insulation Layer with Varying Roughness Regions
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Solution Overview
Problem
Conventional wiring boards with roughened insulation layers to improve adhesion of fine wiring patterns suffer from deteriorated electrical characteristics, leading to poor reliability and peeling issues.
Innovation Solution
A wiring board configuration featuring an insulation layer with alternating regions of different arithmetic mean roughness, where the first wiring conductor is located from a region with a small roughness to a region with a larger roughness, enhancing adhesion and reducing electrical characteristic deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface of the insulation layer is roughened to improve adhesion of fine wiring patterns, then adhesion between wiring pattern and insulation layer is improved, but electrical characteristics deteriorate
Solution Approach 1:
The insulation layer is divided into multiple regions with different arithmetic mean roughness values. Regions with higher roughness (e.g., 0.5-2.0 μm) are positioned where wiring patterns require strong adhesion, while regions with lower roughness (e.g., 0.1-0.5 μm) are positioned where electrical characteristics must be maintained. This spatial variation in surface quality allows simultaneous optimization of both adhesion and electrical performance.
Solution Approach 2:
The insulation layer surface is segmented into distinct regions with different roughness characteristics. This segmentation enables different functional zones: high-roughness zones for enhanced wiring adhesion and low-roughness zones for preserved signal transmission. The segmented approach resolves the contradiction by assigning different surface qualities to different functional requirements within the same insulation layer.
2Volume of moving object
If fine wiring patterns are formed at high density for downsizing, then device size is reduced, but wiring patterns become easily peeled off
Solution Approach 1:
High-roughness regions are strategically positioned in areas where fine wiring patterns are formed to provide enhanced adhesion. The localized increase in surface roughness creates mechanical interlocking and increased surface area for bonding, preventing peeling of densely packed fine wirings while allowing device downsizing to continue.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces the deterioration of electrical characteristics and improves the adhesion of the wiring conductor, making it less likely to peel off while maintaining excellent electrical performance.
Implementation Method 1
a first surface of the insulation layer includes a first region having a first arithmetic mean roughness and a second region having a second arithmetic mean roughness, the second arithmetic mean roughness being larger than the first arithmetic mean roughness
Data Source
AI summary
A wiring board according to the present disclosure includes an insulation layer having a first surface and a second surface opposite to the first surface, and a first wiring conductor located on the first surface. The first surface of the insulation layer includes a first region having a first arithmetic mean roughness and a second region having a second arithmetic mean roughness. The second arithmetic mean roughness is larger than the first arithmetic mean roughness, and the first wiring conductor is located from the first region to the second region.