Gas Sensor Intermediate Layer Design for Connection Reliability
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Solution Overview
Problem
Conventional gas sensors with platinum-based heater sections have high manufacturing costs and suffer from reliability issues due to material incompatibilities and thermal expansion differences, leading to decreased detection accuracy and potential disconnection of the wiring layer.
Innovation Solution
A gas sensor element design where the electrode terminal and wiring layer are composed of different metal materials, with the intermediate layer made of the material with the lower melting point, reducing void formation and increasing connection reliability and detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wiring layer is formed from palladium to reduce manufacturing cost, then manufacturing cost decreases, but voids form in the wiring layer during firing causing disconnection and increased electrical resistance
Solution Approach 1:
A third metal layer is introduced as an intermediary between the palladium wiring layer and the platinum intermediate layer. This third layer has higher affinity for both palladium and platinum, acting as a mediator that prevents direct alloying between these two materials during firing. The third metal layer absorbs the incompatibility between Pd and Pt, eliminating void formation while maintaining the cost advantage of using palladium.
2Adaptability or versatility
If different metal materials are used for the electrode terminal and wiring layer, then manufacturing flexibility increases, but thermal expansion differences cause stress and disconnection
Solution Approach 1:
The third metal layer serves as a thermal expansion buffer between materials with different coefficients of thermal expansion. During temperature cycling, this intermediary layer accommodates the differential expansion and contraction, preventing stress concentration and disconnection at the interfaces between materials with mismatched thermal expansion properties.
3Ease of manufacture
If the intermediate layer and wiring layer are composed of different metal materials, then material optimization is possible, but alloying during firing causes metal movement and void formation
Solution Approach 1:
The third metal layer prevents direct contact and alloying between the intermediate layer and wiring layer during the firing process. By introducing this intermediary barrier, the patent maintains the benefits of material optimization while preventing the harmful alloying reaction that would compromise interface integrity.
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 solution enhances connection reliability and detection accuracy by minimizing electrical resistance increases and preventing disconnection, while maintaining high-temperature performance at a lower manufacturing cost.
Implementation Method 1
the intermediate layer is composed of whichever of the first metal material and the second metal material has the lower melting point
Implementation Method 2
a heater section 980 for heating the solid electrolyte body 97. The heater section 980 includes the wiring layer 92
Data Source
AI summary
A gas sensor element of the present invention detects concentration of a specific gas within a measured gas. The gas sensor element comprises: a wiring layer formed inside a sensor; an insulating layer covering a front surface of the wiring layer; an electrode terminal provided on a main surface of the insulating layer on an opposite side of the insulating layer from the wiring layer, and electrically connected to the wiring layer; and an intermediate layer interposed between the electrode terminal and the wiring layer, and electrically connecting the electrode terminal and the wiring layer. The electrode terminal is composed of a first metal material. The wiring layer is composed of a second metal material. The intermediate layer is composed of whichever of the first metal material and the second metal material has the lower melting point.