Physical Quantity Sensor Stress Isolation via Segmented Beam Structure

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Solution Overview

Problem

Physical quantity sensors, such as angular velocity and acceleration sensors, experience variations in sensor characteristics due to stress transmission from substrates or packages, leading to inconsistencies in measurement.

Innovation Solution

A physical quantity sensor design featuring a substrate, anchor portion, surrounding portion, detecting element, and beam portion, where the beam portions connect the anchor and surrounding portions, reducing stress transmission and improving temperature stability by creating a space that minimizes bonding area between the supporting portions and the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the moving portion is directly connected to the substrate via the anchor portion, then the structural support is strong, but stress is transmitted from the substrate to the moving portion causing sensor characteristic variation

Engineering Contradiction:

Improvestructural supportVSAvoidsensor characteristic stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The supporting structure is divided into multiple independent portions (first supporting portion, second supporting portion, third supporting portion) that are spaced apart from each other. This segmentation reduces stress transmission while maintaining structural support, as the stress from the substrate is distributed across multiple isolated connection points rather than being concentrated in a single continuous structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first beam portion acts as an intermediary element connecting the first supporting portion to the surrounding portion. This intermediate structure allows controlled stress isolation, where the beam portion can absorb or decouple stress transmissions from the substrate while maintaining the structural connection needed for support.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the bonding area between the supporting portions and substrate is large, then the structural stability is high, but stress transmission to the moving portion increases causing temperature sensitivity

Engineering Contradiction:

Improvestructural stabilityVSAvoidstress transmission

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The bonding interface is segmented into multiple discrete bonding regions corresponding to the first, second, and third supporting portions. Each portion bonds to the substrate at separate locations, creating a distributed bonding pattern that reduces continuous stress transmission paths while maintaining overall structural stability through the combined effect of multiple bonding points.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor structure have different bonding characteristics. The first, second, and third supporting portions are positioned at specific locations on the substrate where they provide localized support and bonding. This local quality approach allows the structure to have strong bonding where needed while maintaining stress isolation in other regions, particularly protecting the moving portion from stress transmission.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If the anchor portion is fixed directly to the substrate, then the positioning is precise, but temperature-induced stress from coefficient of linear expansion difference affects sensor characteristics

Engineering Contradiction:

Improvepositioning precisionVSAvoidtemperature stability

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The fixed support structure is segmented into multiple discrete supporting portions rather than a continuous anchor. This segmentation creates thermal isolation zones where temperature-induced expansion and contraction of the substrate do not uniformly transmit stress to the moving portion. Each segmented support can accommodate thermal variations independently, reducing the cumulative thermal stress effect on sensor characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The beam portions serve as intermediary elements between the supporting portions and the surrounding portion. These intermediaries can accommodate differential thermal expansion between the substrate and the sensor structure, acting as a buffer that prevents temperature-induced stress from being directly transmitted to the moving portion while maintaining positional precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11680797B2Physical quantity sensor

Publication Date: 2023.06.20 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A physical quantity sensor includes a substrate, an anchor portion, a surrounding portion, a detecting element, a moving portion, and a beam portion. The anchor portion is formed on the same side as a principal surface of the substrate and fixed to the substrate. The surrounding portion is formed on the same side as the principal surface of the substrate and surrounds the anchor portion. The detecting element detects a physical quantity as a target of detection. The moving portion is provided with at least a part of the detecting element, formed on the same side as the principal surface of the substrate, and connected to the surrounding portion. The beam portion is formed on the same side as the principal surface of the substrate and connects the anchor portion and the surrounding portion together.