Side Wiring Board Structure for Stable Corner Conduction
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Solution Overview
Problem
Existing wiring boards for high-density displays, such as micro-LED displays, face challenges in achieving stable conduction and high connectivity due to issues with conductive paste flow and bonding to non-flat surfaces like glass substrates.
Innovation Solution
A wiring board design featuring a substrate with a main surface, side surfaces, and inclined surfaces, where the wiring has a higher content of conductive particles than insulating components and is applied with a conductive paste that has higher apparent viscosity, reducing flow and ensuring firm bonding at corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive paste is applied to corners of a substrate with conventional composition, then wiring can be formed, but the paste flows downward along the inclined surface and side surface, causing discontinuity and poor conduction stability
Solution Approach 1:
The conductive paste is formulated with high apparent viscosity by adjusting the ratio of conductive particles to insulating component (curable resin) to be greater than 1:1. This parameter change in composition and viscosity prevents the paste from flowing downward along the inclined surface and side surface during application, ensuring continuous wiring formation in corner regions and improving conduction stability.
2Productivity
If wiring thickness is reduced for high-density wiring, then connectivity improves, but conduction stability deteriorates due to thinner wiring
Solution Approach 1:
The wiring is formed as a composite structure containing conductive particles (metal or carbon) dispersed in a curable resin matrix. The insulating component serves dual functions: providing structural support to maintain wiring integrity at reduced thickness, and binding conductive particles together to ensure continuous conduction paths. This composite material approach enables thin wiring with both high density and stable conduction.
3Reliability
If the content of conductive particles is increased to improve conductivity, then the paste becomes too fluid and flows excessively, but if the content is decreased, then conductivity is insufficient
Solution Approach 1:
The conductive paste is designed with a specific composition ratio where conductive particles exceed insulating component content (greater than 1:1 ratio). The high apparent viscosity is achieved by optimizing particle size distribution, particle shape, and resin selection. This parameter optimization allows high conductive particle content for good conductivity while maintaining composition stability and preventing excessive flow during application.
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 results in high-density wiring with stable conduction and improved connectivity, reducing the likelihood of wire breakage and the amount of conductive paste required, while maintaining firm bonding to the substrate surfaces.
Implementation Method 1
A conductive paste for forming wiring has the content of conductive particles greater than the content of an uncured insulating component and thus has higher apparent viscosity and less fluidity
Implementation Method 2
The wiring contains the insulating component of, for example, a curable resin filling fine irregularities on the surfaces of the substrate and improves the bonding force of the wiring
Implementation Method 3
The wiring has a content of conductive particles greater than a content of an insulating component, thus causing the conductive particles to at least easily contact or fuse with one another. Numerous conductive particles are connected to one another with contact portions, fusion portions, or both portions to form a conductive path network, thus providing high conductivity
Data Source
AI summary
A wiring board includes a substrate including a first main surface, a second main surface, a side surface, and an inclined surface connecting the first main surface and the side surface, and side wiring on the first main surface, the inclined surface, and the side surface. The side wiring has a content of conductive particles greater than a content of an insulating component, and the wiring has a thickness equal to a thickness of at least one of the conductive particles in a first corner between the first main surface and the inclined surface and in a second corner between the inclined surface and the side surface.