Ultrasonic Transducer Wire Bonding and Bending Reliability
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Solution Overview
Problem
Ultrasonic array transducers face challenges in maintaining strong electrical connections between transducer elements and cables, particularly when bending wires 90 degrees, due to weak bonding methods like ultrasonic bonding and wedge bonding, which can lead to disconnection and affect acoustic performance.
Innovation Solution
A method involving a transducer element with a piezoelectric ceramic material partially covered by metal plating, where conductors are ultrasonically bonded and sandwiched between the backing material and the transducer element, allowing for bending without disconnection, and connected to an ultrasound system via a cable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wires are bent 90 degrees to connect transducer elements to cables, then electrical connection is achieved, but bond strength is insufficient and connections fail
Solution Approach 1:
The wire is attached to the transducer element before the backing material is applied. This preliminary attachment allows the wire to be positioned and secured in a location that can withstand bending forces, rather than attempting to bond the wire after the rigid backing material is in place. The wire is bonded to the front surface of the transducer element, then the backing material is applied over the entire assembly, encapsulating the wire attachment point and providing structural support during bending operations.
2Strength
If hand soldering is used to connect wires to transducer elements, then strong electrical connection is achieved, but piezoelectric ceramic material is depolarized and performance degrades
Solution Approach 1:
The patent replaces the thermal process of soldering with a mechanical bonding process using ultrasonic bonding or other cold-welding techniques. This mechanical bonding method achieves strong electrical and mechanical connections without applying the high temperatures that would depolarize the piezoelectric ceramic material, thereby maintaining transducer performance while ensuring reliable wire connections.
3Ease of operation
If flexible circuits are used to connect transducer elements, then electrical connection is achieved, but additional layers interfere with acoustic performance
Solution Approach 1:
The patent extracts the electrical connection function from the acoustic path by attaching wires directly to the front surface of the transducer element, away from the acoustic path. The wires are positioned on the front surface and secured there, allowing electrical connections to be made without placing any additional layers or components in the acoustic path between the piezoelectric element and the medium being imaged.
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 method maintains operative connections during bending, enhances structural integrity, and avoids degrading the transducer performance, while keeping additional components out of the acoustic path, thus improving the reliability and efficiency of ultrasonic array transducers.
Implementation Method 1
Each transducer element operates as an independent point source... piezoelectric ceramic material of the transducer elements
Implementation Method 2
The electrical connection between the individual transducer elements and the cable is typically made using a wire... Bonds formed by such methods include ultrasonic bonding
Data Source
AI summary
In a method of making an ultrasonic transducer, a piezoelectric ceramic material that is at least partially covered by metal plating is provided. A plurality of substantially parallel cuts is formed in the plating so as to define a plurality of transducer elements and a ground element. A plurality of conductors is provided. An end portion of each conductor is operatively connected, such as by ultrasonic bonding, to a respective one of the transducer elements or the ground element. Next, a backing material is bonded to the plurality of transducer elements and the ground element such that the end portion of each conductor is sandwiched between the backing material and a respective one of the transducer elements or the ground element. The conductors are bent to allow for operative connection to an ultrasound system. The operative connection between the conductors and the transducer elements is maintained during the bending step.