Gas Sensor Lead Portions Insulating Layer Recess
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Solution Overview
Problem
Conventional gas sensors experience cracks in the lead portions that extend over the insulating layer during manufacturing, leading to incomplete signal pickup from electrode portions due to insufficient conductive paste application and concentrated tensile stress on thin lead patterns.
Innovation Solution
The gas sensor design incorporates an insulating layer with recessed, raised, or recessed and raised end portions to increase the thickness of lead portions extending over the insulating layer, allowing for more even conductive paste application and reducing the likelihood of cracks during drying and baking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lead portion extends over and across the end portion of the insulating layer to suppress catalytic reaction, then the sensing accuracy is improved, but a crack generates in the lead portion during manufacture
Solution Approach 1:
The insulating layer's end portion is designed with a recessed shape to create local variation in thickness. This allows the lead portion to have different thicknesses at different locations: thinner over the recessed area for catalytic activity and thicker at the edges for mechanical strength, thus resolving the contradiction between sensing accuracy and crack prevention
Solution Approach 2:
The solution moves from a two-dimensional planar view to a three-dimensional perspective by creating a recessed structure in the insulating layer. This dimensional change allows the lead portion to extend over the recessed area while maintaining adequate thickness at critical locations, preventing cracks during manufacturing
2Ease of manufacture
If the conductive paste is printed on the end portion of the insulating layer, then the lead portion is formed, but the paste is not sufficiently printed on the corner portion due to surface level difference
Solution Approach 1:
The recessed shape at the end portion of the insulating layer creates local variation in surface height. This allows the conductive paste to be sufficiently printed on the corner portions during the screen printing process, ensuring uniform thickness and preventing cracks during drying and baking
Solution Approach 2:
The insulating layer is pre-formed with a recessed shape before the conductive paste is applied. This preliminary structural preparation ensures that the conductive paste can be uniformly distributed across the corner portions, eliminating the need for additional processing steps
3Object-generated harmful factors
If the lead pattern is made thin to extend over the insulating layer, then the catalytic reaction is suppressed, but the tensile stress is concentrated during drying or baking
Solution Approach 1:
The lead portion is designed with non-uniform thickness: thinner over the recessed insulating layer area to suppress catalytic reactions and thicker at the edges to withstand tensile stress during manufacturing. This local quality variation resolves the contradiction between catalytic suppression and stress resistance
Solution Approach 2:
The recessed shape in the insulating layer acts as a cushioning structure that distributes the tensile stress during drying and baking. This beforehand structural preparation prevents stress concentration in the lead portion, eliminating cracks while maintaining catalytic suppression
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 suppresses crack generation in the lead portions, ensuring accurate gas concentration sensing by maintaining the integrity of the lead patterns and preventing unnecessary catalytic reactions.
Implementation Method 1
a solid electrolyte layer mainly made of, for example, zirconia
Implementation Method 2
a heater arranged to activate the element body by the heating
Implementation Method 3
suppressing catalytic reaction (catalysis)
Data Source
AI summary
A gas sensor includes a substantially cylindrical metal shell; a laminated sensor element held within the metal shell, and including a plate-shaped solid electrolyte layer extending in a longitudinal direction; an electrode portion provided on the solid electrolyte layer; an insulating layer; and a lead portion connected with the electrode portion, extending in the longitudinal direction, and having a front end portion laminated on the solid electrolyte layer, and a rear end portion laminated through the insulating layer on the solid electrolyte layer. The insulating layer has an end portion over and across which the lead portion extends, and which has a recessed shape, a raised shape, or a recessed and raised shape in the longitudinal direction as viewed in the lamination direction.