Ultrasonic Probe Interconnect Resistance Reduction
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Solution Overview
Problem
Increasing the layout density of ultrasonic transducer elements in ultrasonic devices leads to increased interconnect resistance, causing variations in operation timing between elements.
Innovation Solution
A laminated structure is formed with a base layer, an insulating film, and an interconnect layer acting as a conductor, which reduces interconnect resistance by allowing the conductor to function as a bus interconnect for piezoelectric elements, and the interconnect layer is formed by an unpatterned film of conductive material connected to all elements in common, enabling reduced resistance and increased layout density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the layout density of ultrasonic transducer elements is increased, then the resolution of ultrasonic images is improved, but the interconnect resistance increases causing variation in operation timing
Solution Approach 1:
The patent moves the bus interconnect from the same plane as piezoelectric elements to a different layer (interconnect layer) beneath the insulating film. This spatial reorganization in the vertical dimension allows the bus interconnect to extend continuously without being interrupted by electrode patterns, reducing interconnect resistance while enabling higher layout density of transducer elements on the surface.
Solution Approach 2:
The patent introduces an insulating film as an intermediary layer between the bus interconnect and the piezoelectric elements. This insulating film enables the bus interconnect to function effectively by providing electrical isolation, allowing the conductor to spread continuously beneath the elements without direct contact, thereby reducing resistance while maintaining element independence.
2Quantity of substance
If the interconnect width is reduced to increase layout density, then more elements can be arranged, but the interconnect resistance increases
Solution Approach 1:
The bus interconnect is relocated to an interconnect layer beneath the insulating film, allowing it to extend in a different spatial dimension. This enables the conductor to achieve sufficient width and continuous spread without competing for surface space with piezoelectric elements, thus maintaining low resistance while supporting high element density.
Solution Approach 2:
The patent separates the bus interconnect function from the piezoelectric element structure by placing them in different layers. The bus interconnect operates in the interconnect layer while piezoelectric elements occupy the surface layer, allowing independent optimization of each component's dimensions and functions without mutual interference.
3Reliability
If the bus interconnect is laid out between piezoelectric elements, then elements can be connected, but the layout density is reduced
Solution Approach 1:
The bus interconnect is positioned in an interconnect layer beneath the insulating film, creating a three-dimensional arrangement where connectivity functions occur below the active element plane. This allows continuous conductor spread for reliable connectivity while maximizing surface space availability for high-density element placement.
Solution Approach 2:
The insulating film serves multiple functions: it provides electrical isolation between the bus interconnect and piezoelectric elements, supports the interconnect layer structure, and enables the bus interconnect to function as a continuous conductor beneath the elements without disrupting element layout or connectivity.
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 solution effectively reduces interconnect resistance and increases the layout density of ultrasonic transducer elements, preventing contamination by unwanted noise during ultrasonic wave transmission and improving the resolution of ultrasonic images.
Implementation Method 1
A piezoelectric element is mounted on a vibrating film in each ultrasonic transducer element. The piezoelectric element is configured by a piezoelectric film sandwiched between an upper electrode and a lower electrode. A drive voltage is applied to the piezoelectric film from the upper electrode and the lower electrode when ultrasonic vibration is generated. The vibrating film ultrasonically vibrates.
Implementation Method 2
an interconnect layer, which is a conductor, formed on the base layer... The conductor constituting the interconnect layer extends in a layer that is different from the first electrode and the second electrode of the piezoelectric element. Accordingly, the conductor can have a spread not interrupted by the first electrode and the second electrode. The conductor can function as a bus interconnect for the piezoelectric elements. Interconnect resistance can be reduced.
Data Source
AI summary
An ultrasonic device includes a base in which a base layer of a vibrating film is formed in every opening that is disposed in an array; an interconnect layer, which is a conductor, formed on the base layer; an insulating film that is formed on the interconnect layer, and forms a laminated structure with respect to the base layer; a plurality of piezoelectric elements that are separated from the interconnect layer by the insulating film, the piezoelectric elements each including a first electrode and a second electrode that sandwich a piezoelectric film on the insulating film; and a through conductor that passes through the insulating film, and connects at least one of the first electrode and the second electrode to the conductor constituting the interconnect layer.