Stacked Gas Sensor Through-Hole Conductor Crack Prevention
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Solution Overview
Problem
Conventional gas detecting elements face issues with crack formation in the filled through-hole conductor and connecting layers during sintering, leading to unreliable electrical connections due to differential shrinkage among ceramic, insulating, and conductor layers, which affects the reliability of conductor connections.
Innovation Solution
A gas sensor design with a stacked-type gas detecting element featuring a first ceramic layer with a third through hole, a second ceramic layer with a larger second through hole connected to the third through hole, and connecting layers to enhance electrical connection reliability, along with a connection terminal configuration that offsets the connection pad position to improve mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filled through-hole conductor is used to connect connecting layers in a stacked gas detecting element, then electrical connection is achieved, but cracks occur during sintering due to differential shrinkage, reducing reliability
Solution Approach 1:
The patent introduces an intermediary structure (the insulating layer with through-hole) between the ceramic layers and the filled conductor. This intermediary provides a buffer zone that accommodates differential shrinkage during sintering, preventing direct stress transmission to the filled conductor and thus preventing cracks while maintaining electrical connection reliability.
Solution Approach 2:
The patent applies beforehand cushioning by pre-designing the through-hole structure in the insulating layer before sintering. This pre-configured hole provides advance cushioning space that absorbs the shrinkage stress during the sintering process, protecting the filled conductor from crack formation before the stress can cause damage.
2Adaptability or versatility
If multiple ceramic layers are stacked to form the gas detecting element, then functional integration is improved, but differential shrinkage during sintering causes stress and cracks
Solution Approach 1:
The patent segments the gas detecting element into multiple functional ceramic layers (solid electrolyte layer, insulating layer, etc.), each with its own through-hole structure. This segmentation allows each layer to be optimized independently while the overall structure maintains stability through the coordinated design of through-holes that accommodate differential shrinkage across layers.
Solution Approach 2:
The patent applies local quality by giving different regions of the structure different properties - the insulating layer has through-holes with specific dimensions and positions that differ from the ceramic layers. This local differentiation allows each region to handle shrinkage stress appropriately, with the insulating layer's through-holes providing localized stress relief zones that maintain overall structural stability.
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 significantly enhances the reliability of electrical connections and mechanical strength by ensuring stable conductor connections and preventing crack formation during sintering, resulting in a more reliable gas detecting element and sensor.
Implementation Method 1
upon sintering, the stacked body of the unsintered ceramic, the gas detecting element 900 is formed
Implementation Method 2
since the amount of shrinkage upon sintering differs among the unsintered solid electrolyte layer, the unsintered insulating layer (first unsintered insulating layer) and the unsintered conductor, a large stress is applied
Data Source
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AI summary
A gas sensor comprises a gas detecting element (200) extending in a longitudinal direction and in which a plurality of ceramic layers are stacked, and wherein a detecting portion is provided at a leading end side of the gas detecting element (200). The gas detecting element (200) comprises a first ceramic layer (211) having a first surface (211a) and a second surface (211b); a third ceramic layer (221) having a first surface (211a) and a second surface (211b) and having a third through hole (221h1) penetrating therethrough; a second ceramic layer (231) provided between the first surface (211a) of the first ceramic layer (211) and the second surface (221b) of the third ceramic layer (221) and having a second through hole (231h1) connected to the third through hole (221h1), the second through hole (231h1) having an opening area larger than that of the third through hole (221h1); a first connecting layer (213c) provided on the first surface (211a) of the first ceramic layer (211) and exposed in the second through hole (231h1); a second through-hole conductor (235d) provided on an inner peripheral surface of the second through hole (231h1); a second connecting layer (235f) having one end disposed on the first connecting layer (213c) and another end connected to the second through-hole conductor (235d); a third through-hole conductor (227) provided on an inner peripheral surface of the third through hole (221h1); and a third connecting layer (225c) provided on the second surface (221b) of the third ceramic layer (221) and connecting the second through-hole conductor (235d) and the third through-hole conductor (227).