Physical Quantity Sensor Noise Reduction via Segmented Wiring Layout

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Solution Overview

Problem

Physical quantity sensors, such as acceleration or angular velocity sensors, face issues with residual noise due to electrical interference between the sensor element and the semiconductor circuit, particularly caused by serial communication wirings and electrical connections within the package.

Innovation Solution

The physical quantity sensor design includes a configuration where the electrical connection between the sensor element and the semiconductor circuit is positioned on the opposite side of the virtual central line to the serial communication wirings, with a GND wiring placed between them, and uses flip chip packaging to minimize interference, and includes a GND solid pattern to block radiation noise. Additionally, the sensor elements are stacked with multiple substrates to allow for complex wiring without increasing size and are sealed within a closed space to protect from external influences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the sensor element and semiconductor circuit are mounted on a bottom surface of a depression of a package, then the sensor can be compactly integrated, but residual noise is mixed into the signal output due to electrical interference between the wire connecting the sensor element and the SPI wiring inside the package

Engineering Contradiction:

Improvepackage sizeVSAvoidsignal output accuracy

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The package bottom surface is divided into distinct regions: a sensor element mounting region and a wiring region. The SPI wirings are routed through a via hole in the substrate to connect to the semiconductor circuit, separating them spatially from the sensor element's electrical connection portion. This segmentation reduces electrical interference while maintaining compact integration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A substrate acts as an intermediary between the sensor element and the external environment. The substrate includes a via hole that provides a dedicated pathway for SPI wirings to reach the semiconductor circuit without interfering with the sensor element's electrical connections. This intermediary structure enables compact mounting while preventing noise coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If the electrical connection portion is positioned close to the serial communication wirings for compact layout, then the device size is reduced, but electrical interference increases causing residual noise in the sensor signal

Engineering Contradiction:

Improvepackage footprintVSAvoidelectrical interference

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The SPI wirings are routed vertically through a via hole in the substrate rather than horizontally across the bottom surface. This dimensional transition allows the wirings to pass through the substrate thickness, enabling compact planar layout while maintaining spatial separation between the sensor element and communication wirings to minimize interference.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If lead wires are used to connect the sensor element to the semiconductor circuit, then flexibility in wiring is improved, but the device size increases and noise susceptibility increases

Engineering Contradiction:

Improvewiring flexibilityVSAvoiddevice size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

Lead wires are extracted from the package structure entirely. Instead of using flexible lead wires to connect the sensor element to the semiconductor circuit, the design employs direct mounting of the sensor element and semiconductor circuit on the substrate with connections through via holes. This eliminates the need for lead wires, reducing device size and noise susceptibility while maintaining sufficient wiring flexibility through the via hole routing.

Inventive Principle:

Principle #2Taking out (Extraction)

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 significantly reduces residual noise, enhancing the measurement characteristics and accuracy of the sensor, and allows for miniaturization while maintaining high performance by minimizing electrical interference and external noise sources.

Implementation Method 1

a GND wiring is provided on a side on which the electrical connection portion is disposed... a GND solid pattern to block radiation noise

Methodology Applied

Scientific EffectElectromagnetic radiation blocking: Faraday Cage

Implementation Method 2

an electrostatic capacitance type physical quantity sensor (dynamic quantity sensor) which includes a sensor element having movable electrodes and fixed electrodes disposed to face each other in a comb shape. The sensor measures a physical quantity on the basis of electrostatic capacitance generated between both the electrodes.

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Data Source

PatentUS10919758B2Physical quantity sensor, inertial measurement unit, electronic apparatus, portable electronic apparatus, and vehicle

Publication Date: 2021.02.16 SEIKO EPSON CORP

AI summary

A physical quantity sensor includes a substrate, an acceleration sensor mounted on the substrate, an integrated circuit mounted on the substrate and stacked with the acceleration sensor, and serial communication wirings provided to the substrate. In a plan view of the acceleration sensor element, a bonding wire connecting the acceleration sensor element to the integrated circuit is disposed on an opposite side to the serial communication wirings with respect to a virtual central line of the acceleration sensor element.