Wiring Substrate Curved Insulation Layer Prevents Short-Circuits
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Solution Overview
Problem
The existing wiring substrates face challenges in increasing wiring density due to short-circuiting issues caused by conductive material remaining in recesses formed during desmear processing, which hinders throughput yield and reliability, especially when high-density wiring layers are involved.
Innovation Solution
A wiring substrate design featuring a first insulation layer with a curved surface and a second resin layer of lower filler content, where the via wiring layer's end surface is flush with the insulation layer's surface, and the second resin layer is polished to ensure electrical insulation and prevent short-circuits, combined with a method that includes specific resin layer formation and polishing steps to address the desmear processing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If desmear processing is performed to remove insulation layer residues from via hole surfaces, then wiring connection reliability is improved, but conductive material remains in surface recesses causing short-circuit risks
Solution Approach 1:
The patent performs preliminary actions by forming a curved surface on the insulation layer before via hole formation, and subsequently filling surface recesses with resin after desmear processing. This preliminary preparation prevents conductive material from remaining in recesses that would cause short-circuits, while still allowing desmear processing to improve wiring connection reliability by removing insulation residues from via hole surfaces.
Solution Approach 2:
The patent converts the harmful effect of surface recesses (which cause short-circuits) into a beneficial structure by intentionally forming a curved surface design. The curved surface creates controlled recesses that are then filled with insulating resin, transforming potential short-circuit hazards into reliable insulation structures that support high-density wiring.
2Productivity
If wiring density is increased to meet electronic component integration requirements, then device functionality is improved, but short-circuit risks increase due to conductive material in recesses
Solution Approach 1:
The patent performs preliminary actions by forming a curved surface on the insulation layer before via hole formation, and subsequently filling surface recesses with resin after desmear processing. This preliminary preparation prevents conductive material from remaining in recesses that would cause short-circuits, while still allowing desmear processing to improve wiring connection reliability by removing insulation residues from via hole surfaces.
Solution Approach 2:
The patent applies local quality by creating a curved surface with specific geometric properties in localized areas where via holes are formed. The curved surface design with controlled radius of curvature addresses the specific problem of conductive material accumulation in recesses, while maintaining flat surfaces in other areas for high-density wiring placement.
3Productivity
If a flat insulation layer surface is used to support high-density wiring, then wiring density is improved, but conductive material in recesses causes short-circuits
Solution Approach 1:
The patent performs preliminary actions by forming a curved surface on the insulation layer before via hole formation, and subsequently filling surface recesses with resin after desmear processing. This preliminary preparation prevents conductive material from remaining in recesses that would cause short-circuits, while still allowing desmear processing to improve wiring connection reliability by removing insulation residues from via hole surfaces.
Solution Approach 2:
The patent applies local quality by creating a curved surface with specific geometric properties in localized areas where via holes are formed. The curved surface design with controlled radius of curvature addresses the specific problem of conductive material accumulation in recesses, while maintaining flat surfaces in other areas for high-density wiring placement.
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 design enhances the throughput yield by preventing short-circuits and ensuring reliable electrical connections between high-density wiring layers, improving the manufacturing efficiency and reliability of the wiring substrate.
Implementation Method 1
The step of forming the via holes includes laser processing performed on the first insulation layer
Implementation Method 2
The polishing process removes the deposited conductive material from the surface of the first insulation layer to form an end surface of the via wiring layer that is flush with the surface of the first insulation layer
Data Source
AI summary
A wiring substrate includes a first wiring layer, an insulative resin first insulation layer covering the first wiring layer, and a second wiring layer located on an upper surface of the first insulation layer. A via wiring layer, which extends through the first insulation layer to connect the first and second wiring layers, includes an upper end surface connected to the second wiring layer and flush with the upper surface of the first insulation layer. The second wiring layer has a higher wiring density than the first wiring layer. The first insulation layer includes a first resin layer and a second resin layer located on an upper surface of the first resin layer and having a lower filler content rate than the first resin layer. The upper surface of the first resin layer is a curved surface upwardly curved toward the upper end surface of the via wiring layer.