Ultrasonic Probe Vibrator Array Bonding and Filling

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Solution Overview

Problem

The existing manufacturing methods for ultrasonic transducer arrays face issues with vibrations in the width direction, which destabilize the vibration action of piezoelectric elements and negatively impact acoustic characteristics, and previous solutions like thermal deformation and using polishing powder increase costs.

Innovation Solution

The solution involves bonding the bottom of each vibrator to the base plate with a conductive bond material, such as silver paste, and using a multilayer filling material with different rigidity to restrain width-direction vibrations, while improving manufacturing workability and product reliability without additional costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If piezoelectric elements are bonded to the backing material with adhesive and dicing grooves are made to reach the backing material, then the piezoelectric elements can be separated into individual vibrators, but width-directional vibrations occur that destabilize the vibration action in the thickness direction

Engineering Contradiction:

Improvemanufacturing processVSAvoidvibration stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The bond material is applied selectively to surround only the lower part of the side faces of the piezoelectric elements, creating localized mechanical constraint at the critical region where width-directional vibrations originate. This local bonding approach restrains lateral vibrations without affecting the overall vibration action in the thickness direction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bonding structure is segmented to surround each piezoelectric element individually rather than using a continuous bonding layer. This segmentation allows each element to be independently constrained, preventing width-directional vibrations while maintaining the ability of each element to vibrate freely in the thickness direction.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If polishing powder such as alumina powder is mixed in the backing material to prevent thermal deformation during dicing, then thermal deformation is reduced, but manufacturing cost increases

Engineering Contradiction:

Improvethermal deformation controlVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The invention extracts and removes the expensive polishing powder additive from the backing material formulation. Instead of relying on alumina powder mixed in the backing material to prevent thermal deformation, the patent uses the bond material surrounding the piezoelectric elements to provide mechanical constraint, thereby eliminating the need for costly additives while maintaining manufacturing precision.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the piezoelectric elements are formed in an almost trapezoid shape to gradually increase width toward the backing material, then width-directional vibrations are restrained, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvevibration restraintVSAvoidelement geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of modifying the piezoelectric element geometry to trapezoidal shape to restrain vibrations, the invention inverts the approach by modifying the bond material configuration. The bond material is applied to surround the lower part of the side faces, providing vibration restraint through the bonding structure rather than through element shape, thereby simplifying the piezoelectric element geometry while maintaining vibration control.

Inventive Principle:

Principle #13The other way round (Inversion)

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 effectively stabilizes the vibration action of piezoelectric elements in the thickness direction, enhances acoustic characteristics, and improves manufacturing workability and product reliability by restraining width-direction vibrations without increasing costs.

Implementation Method 1

piezoelectric elements as vibrators, an electrode... each piezoelectric element vibrates at high speed in the thickness direction to generate ultrasounds

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the bottom of each vibrator is bonded to the base plate in a manner that lower part of a side face of each vibrator is surrounded by a bond material

Methodology Applied

Scientific EffectMechanical constraint through bonding: Adhesive

Data Source

PatentUS7530151B2Vibrator array, manufacturing method thereof, and ultrasonic probe

Publication Date: 2009.05.12 FUJIFILM CORP

AI summary

In an ultrasonic transducer array, a plurality of vibrators arranged in an array is bonded to a base plate by bond material. The bond material bonds the bottom of the each vibrator to the base plate in a manner to surround lower part of the side face of the vibrator. A filling material is filled in between the vibrators. The filling material has a multi-layer structure of different rigidity. In a double layer structure of the filling material, it is preferable that thickness ratio of layer of filling material at the base plate side (lower side) to the other layer of the filling material is 1:1 to 1:3. Preferably, a beam is provided for connecting the side faces of the adjacent vibrators.