Sensor Module Thermal Stress Reduction via Resin Bonding
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Solution Overview
Problem
Existing sensor modules face decreased detection accuracy due to stress caused by thermal expansion coefficient differences between metal caps and insulating substrates, which affects inertial sensors mounted on these substrates.
Innovation Solution
A sensor module design featuring a printed circuit board with recessed portions and a metal cap with convex portions bonded using an adhesive, where inertial sensors are positioned outside the stress application regions defined by line segments connecting the recessed portions, reducing the impact of thermal expansion stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal cap is coupled to an insulating substrate using soldering at projecting pieces, then the metal cap covers and protects the electronic component, but stress is applied to the insulating substrate and electronic component due to thermal expansion coefficient difference
Solution Approach 1:
The patent introduces a resin layer as an intermediary substance between the metal cap and the insulating substrate. This resin layer acts as a stress-absorbing medium that compensates for the thermal expansion coefficient difference between the metal cap and substrate, thereby reducing stress transmission to the electronic component while maintaining the protective covering function
Solution Approach 2:
The patent changes the bonding method from direct soldering to adhesive bonding using resin. This parameter change in the bonding material properties allows for better thermal expansion compatibility and stress distribution, reducing the harmful stress effects on the electronic component
2Adaptability or versatility
If inertial sensors are mounted on the insulating substrate, then the sensor module can detect motion and acceleration, but detection accuracy decreases due to applied stress
Solution Approach 1:
The resin layer serves as a mediator that isolates the inertial sensors from thermal expansion stress. By placing the sensors on the insulating substrate away from the metal cap bonding regions and using the resin layer to absorb stress, the sensors maintain their detection accuracy while preserving motion and acceleration sensing functionality
Solution Approach 2:
The patent applies different structural qualities to different regions: the metal cap with resin bonding is used for protection and electrical connection areas, while the sensor mounting regions use insulating substrate areas with reduced stress concentration. This local differentiation allows sensors to maintain high measurement precision in their specific zones
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 stabilizes the detection accuracy of inertial sensors by minimizing stress from thermal expansion, resulting in a high-accuracy sensor module.
Implementation Method 1
a first convex portion bonded to the first recessed portion of the printed circuit board, a second convex portion bonded to the second recessed portion, a third convex portion bonded to the third recessed portion, and a fourth convex portion bonded to the fourth recessed portion
Data Source
AI summary
A sensor module includes: a printed circuit board having a first recessed portion formed at a first side, a second recessed portion formed at a second side facing the first side, a third recessed portion formed at a third side, and a fourth recessed portion formed at a fourth side facing the third side; a metal cap including convex portions each bonded to a respective one of the first to fourth recessed portions; and a first inertial sensor and a second inertial sensor that are provided at a main surface of the printed circuit board. The first inertial sensor and the second inertial sensor are disposed outside a region surrounded by a line connecting both ends of the first recessed portion and the second recessed portion and outside a region surrounded by a line connecting both ends of the third recessed portion and the fourth recessed portion.