Ceramic Heater Recessed Lead for Crack Prevention
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Solution Overview
Problem
Ceramic heaters face issues with misalignment and thermal stress-induced cracks due to bumps formed between the heat-generating resistor and leads during manufacturing and usage, which affects their durability and reliability.
Innovation Solution
A ceramic heater design featuring a recessed portion in the lead to house the connecting portion of the heat-generating resistor, reducing thermal stress concentration and preventing cracks, with specific dimensions and shapes for the connecting and main heat-generating portions to enhance adhesion and printing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the heat-generating resistor and leads are separately formed and arranged to partly overlap, then the manufacturing process is simplified, but misalignment occurs and bumps form causing cracks
Solution Approach 1:
The connecting portion of the heat-generating resistor is nested within the recessed portion of the lead, creating a hierarchical structure where one component is partially contained within another. This nesting arrangement ensures precise alignment while maintaining manufacturing simplicity, as the recessed portion acts as a built-in positioning feature that guides the connecting portion into correct placement during the firing process.
Solution Approach 2:
The recessed portion is pre-formed in the lead before the heat-generating resistor is applied. This preliminary action creates a predetermined positioning feature that prevents misalignment during subsequent manufacturing steps. The recessed portion serves as a pre-prepared receptacle that ensures the connecting portion will be correctly positioned when the components are fired together, eliminating alignment issues without requiring complex manufacturing processes.
2Ease of manufacture
If the connecting portion has the same width as the lead, then manufacturing is easier, but thermal stress concentrates causing cracks during rapid heating or cooling
Solution Approach 1:
The connecting portion is designed with different dimensions than the main body of the heat-generating resistor, creating a local variation in geometry. Specifically, the connecting portion has a smaller width and is positioned within the recessed portion of the lead, while the main heat-generating portion maintains its original dimensions. This local quality change reduces thermal stress concentration at the junction area during rapid heating or cooling, preventing cracks while maintaining overall manufacturing simplicity.
3Strength
If the heat-generating resistor is fully embedded in the lead, then adhesion is improved, but thermal stress cannot be effectively distributed
Solution Approach 1:
The connecting portion is partially nested within the recessed portion of the lead, creating an optimized integration where the heat-generating resistor is embedded to the appropriate extent. This nesting arrangement provides sufficient adhesion strength by ensuring close contact between the connecting portion and the lead, while simultaneously allowing thermal stress to be distributed more effectively compared to full embedding, as the recessed portion geometry facilitates stress distribution.
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 design effectively reduces the formation of cracks and enhances the durability and reliability of ceramic heaters by controlling thermal stress and improving adhesion between components, leading to improved manufacturing efficiency and performance.
Implementation Method 1
a heat-generating resistor 3, lead 5 for supplying power to the heat-generating resistor 3
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A ceramic heater comprises a heat-generating resistor, configured for supplying power to the heat-generating resistor, a ceramic body containing the heat-generating resistor and the lead therein. The heat-generating resistor comprises a connecting portion being connected to the lead and having a width less than the width of the lead, and a main heat-generating portion other than the connecting portion. The lead comprises a recessed portion being located at end portion of the lead, being connected to the connecting portion, and being open at an only one side of the longitudinal direction of the lead and an only one side of the thickness direction of the lead. At least a part of the connecting portion is located inside the recessed portion.