Ultrasonic Transducer Electrode with Needle-Like Structures
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Solution Overview
Problem
Small and smoothed piezoelectric elements in ultrasonic transducers face issues with insufficient adhesive strength and conductivity, leading to potential collapse during dicing and electrical conduction failures, which can be exacerbated by the introduction of conductive fillers that deteriorate frequency characteristics.
Innovation Solution
The ultrasonic transducer element incorporates metal needle-like structures on at least one surface of adjacent layers, enhancing adhesive strength through anchor effects and maintaining conductivity without the need for conductive fillers, thereby ensuring reliable electrical connections while preserving frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If piezoelectric elements are made smaller and surfaces are smoothed to enhance image quality and frequency characteristics, then adhesive strength and conductivity between layers become insufficient, causing element collapse during dicing and electrical conduction failures
Solution Approach 1:
The electrode surface is given locally differentiated properties: smooth regions for maintaining frequency characteristics and needle-like protrusions for enhancing adhesive strength and conductivity. This local quality variation allows the same surface to simultaneously achieve both smoothness and high bonding performance.
Solution Approach 2:
The electrode is constructed as a composite structure combining smooth metal surface with needle-like protrusions, creating a multi-functional surface that integrates both adhesive enhancement and electrical conduction capabilities without requiring separate conductive filler materials.
2Reliability
If conductive filler is inserted between layers to prevent electrical conduction failure, then conductivity is improved but film thickness of adhesive layer increases and frequency characteristics deteriorate
Solution Approach 1:
The conductive filler material is completely removed from the adhesive layer. Instead, conductivity is achieved through the needle-like protrusions that directly contact between layers, eliminating the need for conductive fillers and their associated negative effects on frequency characteristics.
Solution Approach 2:
The needle-like protrusions serve as intermediary structures that bridge the gap between layers, providing both mechanical anchoring and electrical conduction pathways without requiring additional conductive filler materials in the adhesive layer.
3Measurement precision
If piezoelectric elements are made smaller to enhance image quality, then resolution is improved but adhesive strength becomes insufficient leading to element collapse during dicing
Solution Approach 1:
The electrode surface is given locally differentiated properties: smooth regions for maintaining frequency characteristics and needle-like protrusions for enhancing adhesive strength and conductivity. This local quality variation allows the same surface to simultaneously achieve both smoothness and high bonding performance.
Solution Approach 2:
The electrode surface transitions from a two-dimensional smooth plane to a three-dimensional structure with needle-like protrusions extending outward. This dimensional change increases the effective bonding area and mechanical interlocking without significantly increasing the lateral footprint of the element.
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 configuration maintains high adhesive strength and conductivity between layers, preventing collapse during processing and ensuring optimal frequency characteristics, even in smaller transducer sizes, with improved reliability and performance.
Implementation Method 1
metal needle-like structures, the pair of adjacent layers being made of a conductive material and facing each other
Implementation Method 2
the conductivity between the individual layers of the ultrasonic transducer element may be insufficient... the needle-like structures... maintaining conductivity without the need for conductive fillers
Data Source
AI summary
An ultrasonic transducer element according to an embodiment includes a plurality of layers including a piezoelectric element layer. At least one surface of electrodes that forms a pair of adjacent layers among the plurality of layers is made of metal including a plurality of needle-like structures, the pair of adjacent layers being made of conductive material and facing each other.