Layered Ceramic Thermistor Structure for High R25 Without Reworking
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Solution Overview
Problem
Conventional thermistors based on sintered ceramic materials lack improved properties for temperature measurement and surge protection, particularly in achieving high R25 values without mechanical reworking, which can risk the ceramic main body.
Innovation Solution
A thermistor with a ceramic main body incorporating an electrically insulating layer of different composition, applied during the production process, which reduces the conducting cross-sectional area to enhance the R25 value without mechanical reworking, using materials like varistor ceramics and capacitor ceramics with spinel structure, and configuring the insulating layer to define the conducting cross-sectional area precisely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conducting cross-sectional area of the ceramic main body is reduced to achieve high R25 values, then the R25 value increases, but the mechanical strength and reliability of the ceramic main body deteriorate
Solution Approach 1:
The invention divides the ceramic main body into multiple functional regions by inserting electrically insulating layers at specific positions. These layers segment the conducting cross-section without reducing the overall physical dimensions of the ceramic main body, thereby maintaining mechanical strength while achieving high R25 values through reduced effective conducting area.
Solution Approach 2:
The invention applies local quality by creating regions with different electrical properties within the ceramic main body. The electrically insulating layers are strategically positioned to reduce conducting cross-sectional area only where needed for R25 adjustment, while other regions maintain full conducting capability and structural integrity.
2Measurement precision
If mechanical reworking is used to reduce the ceramic main body's cross-sectional area to increase R25 value, then the R25 value increases, but the reliability and risk of damage to the ceramic main body worsen
Solution Approach 1:
The invention applies preliminary action by incorporating electrically insulating layers during the green sheet stacking stage, before sintering and final processing. This allows the conducting cross-sectional area to be reduced without mechanical reworking of the sintered ceramic, eliminating the risks of damage while achieving the desired R25 value.
Solution Approach 2:
The invention replaces mechanical reworking (cutting, grinding, or machining of the ceramic main body) with a chemical/compositional approach by inserting electrically insulating layers during green sheet assembly. This substitution eliminates mechanical stress and damage risks while achieving the same electrical effect of reducing conducting cross-sectional area.
3Measurement precision
If the conducting cross-sectional area is reduced to achieve high R25 values, then the R25 value increases, but the production complexity increases due to additional processing steps
Solution Approach 1:
The invention merges the R25 adjustment function with the existing green sheet stacking manufacturing process. By applying electrically insulating layers to green sheets before assembly, the process integrates seamlessly with standard multilayer ceramic production techniques, avoiding the need for separate, complex post-sintering modification steps.
Solution Approach 2:
The electrically insulating layers serve multiple functions: they reduce the conducting cross-sectional area to achieve high R25 values, provide electrical insulation between conductive paths, and can be integrated with existing green sheet processing infrastructure. This multi-functionality reduces overall production complexity despite the added functional capability.
Data Source
AI summary
A thermistor having a ceramic main body, which contains a ceramic material as the main constituent. The ceramic main body has at least one electrically insulating layer. The electrically insulating layer is arranged within the ceramic main body and contains a main component which has a composition different from the ceramic material.