Physical Quantity Detector Circuit Board Stress Reduction
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Solution Overview
Problem
In typical physical quantity detectors for internal combustion engines, the circuit board is prone to damage during mounting due to stress from the adhering process of protective partitions, particularly when using ceramic substrates with glass protection, which can lead to damage of the wiring pattern on the uppermost surface.
Innovation Solution
A physical quantity detector design that integrates the circuit board within the housing using insert molding with a synthetic resin material, reducing stress and damage by forming the circuit board and housing as a single unit, and utilizing inner layer conductors to connect the flow rate detecting portion to the circuit chamber, avoiding surface layer wiring that could be damaged during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a partition is added to protect and seal the circuit portion, then the circuit is protected from damage, but the circuit board receives stress during adhering process which may damage the wiring pattern
Solution Approach 1:
The harmful partition structure is completely removed from the design. Instead of adding a protective partition that causes stress, the invention extracts this unnecessary component and achieves circuit protection through the housing structure itself, eliminating the source of the problem while maintaining the protective function.
Solution Approach 2:
The protective function previously separated into a distinct partition structure is merged into the housing design. The housing now directly provides both structural support and circuit protection, consolidating functions to eliminate the stress-inducing partition while maintaining protection.
2Reliability
If a partition is adhered to the circuit board to seal the circuit chamber, then the circuit chamber is sealed, but the circuit board receives stress which may damage the glass protection layer
Solution Approach 1:
The harmful partition structure is completely removed from the design. Instead of adding a protective partition that causes stress, the invention extracts this unnecessary component and achieves circuit protection through the housing structure itself, eliminating the source of the problem while maintaining the protective function.
Solution Approach 2:
The protective function previously separated into a distinct partition structure is merged into the housing design. The housing now directly provides both structural support and circuit protection, consolidating functions to eliminate the stress-inducing partition while maintaining protection.
3Device complexity
If the flow rate sensor element and electronic components are mounted on the same substrate, then the structure is simplified, but the wiring pattern on the uppermost surface is vulnerable to damage during assembly
Solution Approach 1:
The invention transitions from a two-dimensional surface mounting approach to a three-dimensional integrated structure. By forming the circuit board and housing as a single integrated unit with the circuit chamber formed within the housing, the wiring is protected in the third dimension, eliminating exposure to surface-level damage while maintaining structural simplicity.
Data Source
Figure 1
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AI summary
To prevent a circuit board and circuit board wiring from being damaged at the time of assembling a physical quantity detection device. A physical quantity detection device 300 of the present invention is characterized by having, on a circuit board 400, a sensor unit wherein a flow rate detection unit 602 is disposed, a circuit unit wherein a circuit element is disposed, and a partitioning wall 355 that partitions the sensor unit and the circuit unit from each other. The physical quantity detection device is also characterized in that an internal layer conductor 801 for electrically connecting the flow rate detection unit 602 and the circuit unit to each other is provided on a circuit board 400 internal layer where the partitioning wall 355 is positioned.