Ceramic Heater Via Conductor Adhesion via Surface Inversion
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Solution Overview
Problem
The existing method of forming a ceramic heater by covering a core material with a ceramic sheet often results in stress-induced cracks at the through hole and its periphery due to weak adhesive forces between the via conductor and the inner peripheral surface of the ceramic sheet, leading to exfoliation and crack generation.
Innovation Solution
The method involves punching the ceramic sheet from one surface to the other to create a diametrically enlarged through hole, filling it with an electrically conductive paste, and covering the core material with the ceramic sheet such that the initial punching surface faces outward, enhancing the adhesive force and reducing stress on the via conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the core member is covered with the ceramic sheet with the reverse surface side set as the outer surface, then the heating element can be formed, but stress is applied in a direction that stretches the inner peripheral surface of the through hole and the via conductor, causing the via conductor to exfoliate and cracks to generate
Solution Approach 1:
The patent inverts the orientation relationship between the ceramic sheet surfaces and the via conductor embedding surface. By punching from the reverse surface and making the reverse surface the outer surface, the smooth surface (which provides strong adhesion) is positioned on the outer surface where the via conductor embeds, while the rough surface becomes the inner surface. This inversion resolves the contradiction by ensuring strong adhesive force while maintaining manufacturability.
2Productivity
If the via conductor is embedded in the through hole with weak adhesive force, then the manufacturing process can be completed, but the via conductor is likely to exfoliate from the inner peripheral surface under stress, inducing crack generation
Solution Approach 1:
The patent applies inversion to the punching direction and surface orientation, which fundamentally changes the adhesion characteristics. By punching from the reverse surface and making it the outer surface, the via conductor embeds into a smooth surface with strong adhesive force. This inversion simultaneously improves reliability (preventing exfoliation and cracks) and maintains productivity, as the manufacturing process remains efficient while producing a more reliable product.
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 approach significantly reduces the occurrence of cracks in the through hole and its periphery, particularly in small-diameter heaters, by increasing the adhesive force and distributing stress in a way that suppresses displacement between the via conductor and the through hole.
Implementation Method 1
The lead portion is connected to an electrode pad formed on the outer peripheral side in the cylindrical ceramic sheet through a via conductor in a through hole formed in the ceramic sheet, thereby realizing electrical conduction to the heating element
Data Source
AI summary
A ceramic heater includes a core material and a ceramic sheet covering the core material, and wherein a side of the ceramic sheet opposite the core material is an outer side of the ceramic heater. A method for manufacturing the ceramic heater includes forming a through hole in a ceramic sheet which is diametrically enlarged from a first surface toward a second surface of the ceramic sheet, forming a via conductor, forming on the second surface a heating portion and lead portion for connecting the heating portion and the via conductor, and covering a core material with the ceramic sheet such that the first surface faces an outer side of the ceramic heater.