Thermistor Element Thin Underlayer Corners
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chip-type thermistor elements face challenges in reducing size and height while maintaining reliability in wire bonding, with issues of electrode peeling and cracking, and insufficient adhesion to wire.
Innovation Solution
The thermistor element design features ceramic construction with thin underlayer corner portions and edge portions that absorb internal stress, preventing peeling and cracking, and includes arcuate recesses to prevent short circuits, with specific dimensions and shapes of external electrodes to ensure non-contact and increased adhesion during wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size and height of thermistor elements are reduced, then the demand for miniaturization is met, but electrode peeling and cracking occur reducing reliability
Solution Approach 1:
The patent applies local quality by creating thin corner portions at specific locations of the external electrodes (at the four corners of the upper surface and lower surface). These localized thin regions serve as stress absorption zones that prevent peeling and cracking, while the rest of the electrode maintains sufficient thickness for reliable wire bonding. This resolves the contradiction by enabling miniaturization without compromising overall electrode integrity.
Solution Approach 2:
The external electrodes are segmented into different thickness regions - thin corner portions and thicker central portions. This segmentation allows the electrode to simultaneously achieve small overall size (through thin corners reducing total material and enabling compact design) while maintaining reliability (through thicker central regions providing structural strength and wire bonding surface).
2Ease of manufacture
If conventional electrode structures are used in miniaturized thermistors, then manufacturing is simple, but electrode peeling and cracking reduce reliability
Solution Approach 1:
The patent changes the geometric parameters of the electrode, specifically creating thin corner portions with controlled dimensions (width of 10-50 μm, length of 50-100 μm). This parameter modification allows the electrode to absorb stress effectively while maintaining compatibility with conventional manufacturing processes like screen printing or thick film deposition, thus improving reliability without sacrificing ease of manufacture.
3Volume of moving object
If external electrodes are made thinner to reduce size, then miniaturization is achieved, but adhesion to wire bonding deteriorates
Solution Approach 1:
The electrode design implements local quality by maintaining thin thickness only at corner portions (10-50 μm width) while keeping the central bonding areas sufficiently thick. This localized thinning achieves miniaturization and stress absorption without compromising the adhesion quality at wire bonding locations, as the central regions retain adequate thickness for reliable wire attachment.
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 design effectively reduces the size and height of thermistor elements while significantly enhancing wire bonding reliability by preventing electrode peeling, cracking, and short circuits, allowing for smaller sizes like the 0603 size while maintaining flatness and adhesion.
Implementation Method 1
thin portions of the underlayers absorb internal stress of the metal plating layers, thus significantly reducing or preventing the external electrodes from peeling off and significantly reducing or preventing cracks from being generated
Data Source
AI summary
A thermistor element includes an element body made of ceramic and including first and second end surfaces opposite to each other and a peripheral surface located between the first end surface and the second end surface, first and second external electrodes respectively covering the first and second end surfaces and portion of the peripheral surface adjacent to the respective first and second end surfaces. The first and second external electrodes include electrode layers including an underlayer and a metal plating layer, the underlayer of the first external electrode includes, adjacent to or in a vicinity of the second external electrode, two second external electrode side corner portions that are thin and adjacent to each other, and the underlayer of the second external electrode includes, adjacent to or in a vicinity of the first external electrode, two first external electrode side corner portions that are thin and adjacent to each other.