Sensor Housing Adhesive Bead Sealing
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Solution Overview
Problem
Current pressure sensor designs face challenges in achieving media tightness and preventing corrosion, especially when separating sensor elements and electronic components, which are essential for enhanced exhaust gas resistance and variable customer-specific configurations.
Innovation Solution
The solution involves using MID technology to create a conductor track on a plastic base plate with gold metallization, where the conductor track is elevated in depressions and connected to the sensor element and electronic component with bonding wires, and an adhesive bead is applied between the bonding points to form a robust and media-tight seal, ensuring the electronic component remains isolated from the medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor element and electronic component are housed in separate chambers to improve exhaust gas resistance, then the electronic component is protected from media exposure, but achieving media-tight separation becomes difficult
Solution Approach 1:
An adhesive bead is introduced as an intermediary sealing element between the conductor comb and the housing wall. This adhesive bead fills the gap and creates a media-tight seal, preventing exhaust gases and moisture from penetrating into the electronic component chamber while maintaining reliable separation between the sensor element and electronic component chambers
Solution Approach 2:
The housing structure employs composite material construction with different material properties for different functional regions. The conductor comb is made of corrosion-resistant material (gold-plated or stainless steel) while the housing is made of plastic or metal, creating a composite structure that combines electrical conductivity, corrosion resistance, and sealing capabilities
2Reliability
If a leadframe is injection-molded into the housing with tight overmolding to prevent moisture ingress, then media tightness is improved, but the bonding process attacks the gold surface promoting corrosion
Solution Approach 1:
The conductor comb is extracted from the traditional leadframe structure and redesigned as a separate, corrosion-resistant component. By removing the vulnerable gold-plated leadframe and replacing it with a corrosion-resistant conductor comb made of stainless steel or gold-plated material that is mechanically integrated into the housing, the solution eliminates the corrosion problem while maintaining electrical functionality
Solution Approach 2:
The conductor comb is designed as a sacrificial or replaceable component with extended service life. By using corrosion-resistant materials and optimized geometry, the conductor comb can withstand the bonding process and long-term exposure to exhaust gases, eliminating the need for frequent replacement and reducing lifecycle costs
3Device complexity
If the sensor element and electronic component are integrated into the same silicon chip or housing area to reduce complexity, then device complexity is reduced, but exhaust gas resistance of the electronic component cannot be ensured
Solution Approach 1:
The sensor housing is segmented into distinct functional chambers: a first chamber housing the sensor element exposed to the medium, and a second chamber housing the electronic component protected from the medium. The conductor comb acts as a shared interface element that electrically connects both chambers while being mechanically integrated into the housing, achieving spatial separation without excessive complexity
Solution Approach 2:
The conductor comb serves multiple functions simultaneously: it provides electrical connection between the sensor element and electronic component, acts as a structural support element, and functions as a sealing reference surface for the adhesive bead. This multi-functionality reduces the number of separate components needed while maintaining reliable media separation
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 approach results in a more robust, cost-effective, and electromagnetically compatible pressure sensor with improved exhaust gas resistance by maintaining a media-tight connection between the sensor element and electronic component, reducing mechanical stress on bonding points and enhancing assembly efficiency.
Implementation Method 1
an adhesive bead is applied between the bonding points to form a robust and media-tight seal
Implementation Method 2
a gel can be applied to the medium-exposed side of the base plate, which preferably covers the bonding points and the bonding wires
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to a sensor (10) having a sensor housing (12), an electronic component (16), and a sensor element (18). The electronic component (16) and the sensor element (18) are interconnected in a media-tight manner. An adhesive (28) serving as a seal is placed between bonding sites (22, 24) of a bonding wire (26) of the at least one electrical connection (24).