Ceramic Lighting Device Glass Coating Fixation Strength
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Solution Overview
Problem
The fixation strength between the surrounding wall member and the board in ceramic-based lighting devices is reduced, leading to potential airtightness issues and performance deterioration due to external stress or thermal impact.
Innovation Solution
Incorporating a coating portion made of glass material between the board and the joining portion, with a center line mean roughness exceeding 0.3 µm, and using a silicone-based adhesive with a higher linear expansion coefficient than the board but lower than the surrounding wall member to enhance adhesion and thermal stress management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a board made of ceramics is used, then heat dissipation and electrical insulation are improved, but fixation strength between the surrounding wall member and the board is reduced
Solution Approach 1:
A coating layer made of glass material is introduced as an intermediary between the ceramic board and the surrounding wall member. This coating layer has a linear expansion coefficient intermediate between the ceramic board and the surrounding wall member, acting as a buffer that reduces thermal stress and improves adhesion. The glass material coating serves as a mediator that resolves the incompatibility between the ceramic board and the surrounding wall member, thereby improving fixation strength while maintaining the heat dissipation and electrical insulation properties of the ceramic board.
Solution Approach 2:
The linear expansion coefficient parameter is optimized by selecting glass material with specific properties. The coating layer's linear expansion coefficient is designed to be between that of the ceramic board and the surrounding wall member, creating a gradient that reduces thermal stress. This parameter optimization allows the system to withstand thermal cycling without compromising fixation strength, thereby resolving the contradiction between using ceramic for heat dissipation and maintaining strong fixation.
2Ease of manufacture
If fixation strength is reduced, then manufacturing simplicity is maintained, but airtightness and reliability deteriorate due to separation under stress
Solution Approach 1:
The glass material coating serves as an intermediary that improves the bonding interface between the surrounding wall member and the ceramic board. By providing a surface with intermediate properties, it enhances adhesion and prevents separation under external stress or thermal impact, thereby maintaining airtightness without complicating the manufacturing process. The coating can be applied using conventional techniques, preserving manufacturing simplicity while significantly improving reliability.
3Strength
If a coating portion with roughness exceeding 0.3 µm is applied, then adhesion strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The surface roughness parameter of the glass material coating is optimized to exceed 0.3 µm center line mean roughness. This controlled roughness increases the surface area and mechanical interlocking between the coating and the surrounding wall member, thereby improving adhesion strength. The glass material coating process can be controlled within standard manufacturing tolerances to achieve the required roughness without imposing excessive precision requirements, balancing adhesion improvement with manufacturing feasibility.
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 configuration improves the fixation strength, prevents tilting of the surrounding wall member, minimizes malfunctions due to pinholes, and enhances the reliability and airtightness of the lighting device.
Implementation Method 1
a coating portion that is provided between the board and the joining portion and contains a glass material... with a center line mean roughness exceeding 0.3 µm
Implementation Method 2
using a silicone-based adhesive with a higher linear expansion coefficient than the board but lower than the surrounding wall member to enhance adhesion and thermal stress management
Data Source
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Figure 5~6
AI summary
A lighting device according to an embodiment includes a board that contains ceramics on at least a surface thereof, a light emitting element that is provided on the surface of the board, a wiring pattern that is provided on the surface of the board and is electrically connected to the light emitting element, a surrounding wall member that is provided to surround the light emitting element, a joining portion that is provided between the board and the surrounding wall member, and a coating portion that is provided between the board and the joining portion and contains a glass material.