Compact Physical Quantity Sensor with Flexible Support Member
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Physical quantity sensors face challenges in maintaining measurement characteristics due to thermal stress caused by differences in thermal expansion coefficients between the package and the mounting substrate, leading to size constraints and instability in measurement accuracy.
Innovation Solution
A physical quantity sensor design featuring a support member with a smaller surface area than the sensor unit, which alleviates thermal stress by reducing the transmission of strain to the measurement unit, and includes signal terminals positioned outside the support member to minimize interference noise, while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a package is mounted on a mounting substrate via a relay substrate with a constricted portion to absorb thermal expansion, then thermal stress is reduced, but the device size increases
Solution Approach 1:
The invention extracts the strain-absorbing function from a separate constricted portion structure and integrates it into the support member itself. The support member's flexible portion provides the necessary elastic deformation capability without requiring additional projecting portions, thereby reducing device size while maintaining thermal stress compensation.
Solution Approach 2:
The invention merges the support function and the thermal expansion compensation function into a single support member structure. The flexible portion of the support member simultaneously provides mechanical support and absorbs strain through elastic deformation, eliminating the need for separate strain-absorbing components.
2Volume of moving object
If the support member surface area is reduced to minimize device size, then device size decreases, but thermal stress transmission to the sensor unit increases
Solution Approach 1:
The invention applies local quality by creating a flexible portion with specific material properties or structural characteristics in a localized region of the support member. This flexible portion has different mechanical properties (higher flexibility) compared to other parts, allowing it to concentrate strain absorption while keeping the overall support member compact.
Solution Approach 2:
The invention changes physical parameters of the support member, specifically making the surface area of the first surface smaller than the container outer edge area (S2 < S1). This parameter change, combined with creating a flexible portion, enables the support member to absorb thermal expansion strain effectively while maintaining a compact size.
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 effectively reduces the impact of thermal stress on measurement characteristics, allowing for a compact and stable physical quantity sensor with improved accuracy and reduced noise interference.
Implementation Method 1
the flexible portion of the support member has a function of reducing stress to be applied to the sensor unit when undergoing a temperature cycle
Implementation Method 2
it is possible to alleviate strain caused by thermal stress due to the difference in the thermal expansion coefficients between the support member and the substrate
Data Source
AI summary
A physical quantity sensor includes an acceleration sensor having an acceleration sensor element and a package accommodating the acceleration sensor element, a support member having a first surface and supporting the acceleration sensor on the first surface, and an IC chip to which a second surface facing the first surface of the support member is attached, in which, in a plan view from a stacking direction of the acceleration sensor and the support member, in a case where an area of a region surrounded by an outer edge of the package is S1 and an area of the first surface is S2, S1≥S2 is satisfied.