Ultrasonic Sensor Flexible Substrate Connection

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Solution Overview

Problem

Existing ultrasonic sensors are prone to electrical disconnection between pin terminals and piezoelectric elements due to repeated external forces, leading to fractures in connection portions and potential disconnection, especially when subjected to pulling forces.

Innovation Solution

The use of a flexible substrate instead of traditional lead wires, which is elastically deformed and bent to distribute stress evenly, reducing the likelihood of fracture and maintaining electrical connection, and increasing the contact area with a damping member to prevent resin fracture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lead wires are used to connect pin terminals to piezoelectric elements, then electrical connection is achieved, but the connection is prone to fracture and disconnection when subjected to external forces

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidresistance to external force
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent replaces rigid lead wires with a flexible substrate that can elastically deform under external forces. The flexible substrate maintains electrical connection while accommodating mechanical stress through elastic deformation, preventing fracture and disconnection when the sensor is subjected to pulling or tilting forces.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the mechanical properties of the connection component from rigid (lead wire) to flexible (flexible substrate). This parameter change allows the connection to adapt to external forces through elastic deformation, improving both reliability and strength under mechanical stress.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If pin terminals are rigidly fixed in the case opening, then electrical connection is stable, but the structure becomes vulnerable to fracture under pulling forces

Engineering Contradiction:
Improveelectrical connection stabilityVSAvoidvulnerability to pulling force
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces dynamic flexibility to the connection structure through the flexible substrate. Instead of a rigid fixed connection, the flexible substrate can deform dynamically under external forces while maintaining electrical connection, allowing the structure to adapt to pulling and tilting forces without fracturing.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The flexible substrate acts as a cushioning element that absorbs and distributes mechanical stress before it can cause fracture. By elastically deforming under external forces, the flexible substrate protects the rigid pin terminals and connection portions from damage, preventing fracture before it occurs.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If traditional lead wires are used for connection, then manufacturing is simple, but repeated deformation leads to fracture and disconnection

Engineering Contradiction:
Improveconnection simplicityVSAvoidconnection durability under repeated stress
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The flexible substrate maintains ease of manufacture while significantly improving durability. The substrate can be integrated into the sensor structure and maintains electrical connection through elastic deformation, preventing the fracture that occurs with lead wires under repeated stress cycles.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent replaces the mechanical lead wire system with a flexible substrate system that uses elastic deformation instead of rigid mechanical connection. This substitution allows the connection to withstand repeated stress cycles without fracturing, improving duration of action while maintaining manufacturing simplicity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 flexible substrate design enhances the reliability of the connection between pin terminals and piezoelectric elements, preventing electrical disconnection and reducing the risk of fracture under various external forces, including pulling and tilting, thereby improving the sensor's resistance to mechanical stress.

Implementation Method 1

The flexible substrate is elastically deformed and bent to distribute stress evenly

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The piezoelectric element is formed of piezoelectric ceramics, and includes a disc-shaped piezoelectric substrate and a pair of electrodes

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

The damping member seals the one of the end portions of the pin terminal and the flexible substrate in the case

Methodology Applied
Scientific EffectDamping: Damping

Data Source

PatentEP2765789B1Ultrasonic sensor
Publication Date: 2022.10.05 MURATA MFG CO LTD
  • EP2765789B1 patent drawingFigure 1(A)~1(B)
  • EP2765789B1 patent drawingFigure 2(A)~2(B)
  • EP2765789B1 patent drawingFigure 3(A)~3(C)

AI summary

An ultrasonic sensor (1) includes a cylindrical case (2) having a bottom, which includes a bottom plate (2B) and a side wall (2A); a piezoelectric element (3) that is disposed at the bottom plate (2B) in the case (2); a pin terminal (11A, 11B), one of end portions thereof being disposed in an opening of the case (2) and the other end portion thereof being disposed outside of the case (2); a strip-shaped flexible substrate (9) including a first end and a second end, the first end being connected to the one of the end portions of the pin terminal (11A, 11B), the second end being connected to the piezoelectric element (3); and a damping member (8) that seals the one of the end portions of the pin terminal (11A, 11B) and the flexible substrate (9) in the case (2). The flexible substrate (9) is bent and disposed in the opening of the case (2) so that the first end extends in a same direction as the one of the end portions of the pin terminal (11A, 11B) and so that the flexible substrate (9) bends from the first end, extends towards the side wall (2A) of the case (2), and terminates in the second end.