Ultrasound Transducer Acoustic Stack with Integral Electrical Connections

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Solution Overview

Problem

Conventional methods for making electrical connections in ultrasound transducers are difficult and expensive, compromising acoustic isolation and requiring high-cost, high-precision techniques.

Innovation Solution

A method involving a flex circuit with conductive traces and a piezoelectric block bonded to it, where the block is diced to create individual transducer elements electrically isolated from each other, allowing for direct bonding to the conductive traces, thereby establishing an electrical interface without compromising acoustic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrical connection methods (edge bonding, wire bonding, ceramic fingers) are used to maintain acoustic isolation, then acoustic performance is preserved, but manufacturing complexity and cost increase significantly

Engineering Contradiction:
Improveacoustic isolationVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the electrical connection function and acoustic isolation function into a single integrated layer. The PTFE-coated flexible circuit board serves simultaneously as the electrical interconnection medium and as the acoustic isolation layer, eliminating the need for separate components and complex assembly processes while maintaining both electrical connectivity and acoustic performance

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flexible circuit board with PTFE coating performs multiple functions: it provides electrical connections between piezoelectric elements, serves as an acoustic isolation layer, and acts as a structural support substrate. This multi-functional design simplifies the overall device architecture and manufacturing process

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If conventional electrical connection methods are used, then acoustic isolation is maintained, but manufacturing cost increases due to high-precision requirements

Engineering Contradiction:
Improveacoustic isolationVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the electrical connection function and acoustic isolation function into a single integrated layer. The PTFE-coated flexible circuit board serves simultaneously as the electrical interconnection medium and as the acoustic isolation layer, eliminating the need for separate components and complex assembly processes while maintaining both electrical connectivity and acoustic performance

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a cost-effective flexible circuit board with PTFE coating that can be manufactured using standard PCB fabrication processes. This approach replaces expensive, precision-critical components with more affordable, easily manufacturable materials that achieve the same functional requirements

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If very fine wire attachments are used to go through backing layers, then acoustic stack is not affected, but alignment precision and manufacturing difficulty increase

Engineering Contradiction:
Improveacoustic stack integrityVSAvoidalignment precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent extracts the wire bonding step entirely from the manufacturing process. Instead of inserting fine wires through the acoustic stack, the electrical connections are established through the PTFE-coated flexible circuit board that bonds directly to the piezoelectric elements, eliminating the need for precision wire alignment and insertion

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The electrical connection pattern is pre-established on the flexible circuit board before assembly. The conductive traces are fabricated in advance on the PTFE-coated substrate, eliminating the need for precision alignment during the assembly process and simplifying manufacturing

Inventive Principle:
Principle #10Preliminary action

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 approach enables cost-effective manufacturing of ultrasound transducers with improved acoustic performance by simplifying the electrical interface process while maintaining acoustic isolation.

Implementation Method 1

a core of piezoelectric material

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a conductive coating disposed beneath the core... a plurality of conductive traces disposed on top of the insulating layer

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

The flexible substrate also acts as an acoustic matching layer between the piezo-electric ceramic transducer elements and human tissues or blood of the patient

Methodology Applied
Scientific EffectAcoustic transmission: Acoustics

Data Source

PatentEP2459322B1Ultrasound imaging transducer acoustic stack with integral electrical connections
Publication Date: 2014.11.05 IMACOR INC
  • EP2459322B1 patent drawingFigure 1~2
  • EP2459322B1 patent drawingFigure 3A~4
  • EP2459322B1 patent drawingFigure 5A~5B

AI summary

An ultrasound transducer that includes a backing layer 11, an insulating layer 15a disposed on top of the backing layer, and a plurality of conductive traces 15b disposed on top of the insulating layer are disclosed. Each of the conductive traces has an upper face. A plurality of transducer elements 20, each having (a) a core of piezoelectric material and (b) a conductive coating disposed beneath the core, are bonded directly to the upper face of a respective one of the plurality of conductive traces. Methods for fabricating ultrasound transducers are also disclosed.