Printed Wiring Board Conductor Roughness for Low Transmission Loss
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Solution Overview
Problem
Existing printed wiring boards face challenges in minimizing transmission losses, particularly due to the presence of recesses with depths of 2.0 μm or more and bottom diameters larger than the opening diameters, which increase the roughness and adhesion issues.
Innovation Solution
The printed wiring board incorporates resin insulating layers and conductor layers with a specific structure, where the conductor layers feature a conductor circuit with a limited number of recesses (10 or less per 100 μm length) that meet the depth and diameter criteria, thereby reducing transmission losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the conductor layers have many deep recesses (depth ≥ 2.0 μm with bottom diameter larger than opening diameter), then the surface area increases for better adhesion, but the transmission loss increases due to increased roughness
Solution Approach 1:
The patent changes the parameter of recess depth from unlimited to specifically controlled (depth ≥ 2.0 μm but with limited quantity), transforming the surface structure to achieve both good adhesion and low transmission loss by limiting the number of deep recesses to 10 or less per 100 μm length
2Loss of energy
If the conductor layers are formed with smooth surfaces (low roughness), then the transmission loss is reduced, but the adhesion to resin insulating layers deteriorates
Solution Approach 1:
The patent applies local quality by creating specific deep recesses (with depth ≥ 2.0 μm and bottom diameter larger than opening diameter) in localized areas of the conductor layer, rather than uniformly roughening the entire surface. This localized structuring provides adhesion points while maintaining overall surface smoothness for low transmission loss
Data Source
AI summary
A printed wiring board includes resin insulating layers, and conductor layers laminated on the resin insulating layers, respectively. The conductor layers includes a conductor layer including a conductor circuit formed such that the conductor circuit has recesses each having a depth of 2.0 μm or more and a bottom whose diameter is larger than a diameter of an opening part of a respective one of the recesses.