Wiring Substrate with Selective Surface Roughness
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Solution Overview
Problem
Miniaturization of wiring layers leads to increased voids and surface roughness, resulting in higher resistance and reduced reliability of electrical properties due to the roughening process used to enhance adhesion between wiring and insulating layers.
Innovation Solution
A wiring substrate design with a first and second wiring structure, where the second wiring structure has a higher density and a roughened surface with smaller surface roughness than the first, and a method for manufacturing involving selective roughening of specific surfaces to maintain planar shape and adhesion without increasing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a roughening process is performed on miniaturized wiring layers to increase adhesion, then adhesion between wiring layer and insulating layer is improved, but the wiring layer develops excessive surface roughness and voids, increasing resistance and reducing electrical reliability
Solution Approach 1:
The patent applies different surface treatments to different wiring layers based on their specific requirements. The first wiring layer undergoes a roughening process to enhance adhesion, while the second miniaturized wiring layer maintains a smoother surface to avoid excessive roughness and void formation. This local differentiation allows each layer to have optimal surface properties for its function.
Solution Approach 2:
The patent changes the surface roughness parameter differently for different wiring layers. The first wiring layer is given a larger surface roughness through roughening treatment, while the second wiring layer is kept with smaller surface roughness. This parameter optimization resolves the contradiction between adhesion requirements and electrical reliability for miniaturized wiring.
2Productivity
If wiring layers are miniaturized to increase wiring density, then wiring density is improved, but the roughening process creates more voids and increases surface roughness, leading to higher resistance
Solution Approach 1:
The patent implements selective surface treatment where only the first wiring layer undergoes roughening, while the second miniaturized wiring layer maintains a smoother surface. This local quality differentiation allows the second wiring layer to achieve high wiring density while preserving planar shape precision and minimizing void formation.
Solution Approach 2:
Instead of applying roughening treatment uniformly to all wiring layers, the patent applies it partially only to the first wiring layer. This partial action approach prevents excessive roughness in the second miniaturized wiring layer, maintaining both high wiring density and manufacturing precision.
3Strength
If roughening process is applied to increase adhesion, then adhesion is improved, but the desired planar shape of wiring layer is compromised
Solution Approach 1:
The patent applies roughening treatment locally only to the first wiring layer where adhesion enhancement is most needed, while the second wiring layer maintains a smoother surface to preserve its planar shape. This localized approach allows adhesion improvement without compromising the planar geometry of miniaturized wiring patterns.
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 increases adhesion between wiring and insulating layers while maintaining desired planar shape and minimizing resistance, enhancing the reliability and performance of miniaturized wiring layers.
Implementation Method 1
a roughening process is performed on the wiring layer to increase the adhesion between a wiring layer and an insulating layer that covers the wiring layer
Data Source
AI summary
A wiring substrate includes a first wiring structure and a second wiring structure. The first wiring structure includes a first insulating layer, which covers a first wiring layer, and a via wiring. A first through hole of the first insulating layer is filled with the via wiring. The second wiring structure includes a second wiring layer and a second insulating layer. The second wiring layer is formed on an upper surface of the first insulating layer and an upper end surface of the via wiring. The second wiring layer partially includes a roughened surface. The second insulating layer is stacked on the upper surface of the first insulating layer and covers the second wiring layer. The second wiring structure has a higher wiring density than the first wiring structure. The roughened surface of the second wiring layer has a smaller surface roughness than the first wiring layer.