Wiring Substrate Conductor Pad Surface Roughness Design
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Solution Overview
Problem
Existing wiring substrates face issues with interface peeling between metal wiring layers and insulating layers due to stress during manufacturing and use, leading to deterioration in quality and transmission characteristics, especially for high-frequency signals.
Innovation Solution
A wiring substrate design featuring a first conductor layer with a conductor pad having distinct surface regions of different roughness, where the coating film covers one region and the connection conductor covers the other, enhancing adhesion and preventing peeling, while maintaining low surface roughness for improved transmission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the surface of the conductor pad is roughened to enhance adhesion between the coating film and the conductor layer, then adhesion strength is improved, but surface roughness increases leading to deterioration in high-frequency transmission characteristics
Solution Approach 1:
The conductor pad surface is divided into two regions with different roughness: a first region with higher surface roughness for enhanced adhesion where the coating film is formed, and a second region with lower surface roughness for maintaining good transmission characteristics. This local differentiation allows each region to optimize its function independently.
Solution Approach 2:
The conductor pad surface is segmented into multiple functional zones (first region and second region) with distinct surface properties. The first region serves the adhesion function while the second region serves the transmission function, resolving the contradiction by separating these conflicting requirements into different spatial zones.
2Stability of the object's composition
If a coating film is formed on the entire conductor layer surface to improve adhesion, then interface peeling is suppressed, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The conductor pad surface is prepared in advance with differentiated roughness regions before coating film formation. This preliminary surface preparation enables selective coating adhesion without requiring complex masking or patterning processes during the coating step, thereby reducing overall manufacturing complexity while maintaining interface stability.
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
The solution effectively suppresses peeling and ensures desired characteristics for wiring patterns and adhesion, maintaining high-frequency transmission quality and preventing conductor pad temperature rises during manufacturing.
Implementation Method 1
a coating film formed on a surface of the first conductor layer such that the coating film is adhering the first conductor layer and the insulating layer
Data Source
AI summary
A wiring substrate includes a first conductor layer, an insulating layer formed on the first conductor layer, a second conductor layer formed on the insulating layer, a connection conductor penetrating through the insulating layer and connecting the first and second conductor layers, and a coating film formed on a surface of the first conductor layer and adhering the first conductor layer and the insulating layer. The first conductor layer includes a conductor pad in contact with the connection conductor such that the conductor pad has a surface having a first region and a second region on second conductor layer side and that surface roughness of the first region is different from surface roughness of the second region, and the conductor pad of the first conductor layer is formed such that the first region is covered by the coating film and that the second region is covered by the connection conductor.