Capacitance Transducer Through-Hole Electrode Connection
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Solution Overview
Problem
Manufacturing broadband capacitance type transducers with high-output acoustic pressure is challenging due to limitations in withstand voltage and fluctuations in vibrating film thickness, which affect both transmitting/receiving sensitivity and reliability.
Innovation Solution
A method involving forming a sacrificial layer, a vibrating film, and a sealing film, with a conductor film electrically connecting the second electrode through a through hole in the insulating film, allowing for independent adjustment of electrode distances and enhancing withstand voltage without compromising sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the distance between electrodes is set to be small to achieve high-efficiency and high-output acoustic pressure, then the acoustic pressure output is improved, but the withstand voltage is reduced, which limits the applicable voltage range
Solution Approach 1:
The patent introduces a through-hole structure that extends vertically through the upper electrode and insulating film, creating a new dimensional path for electrical connection. This allows the electrode distance in the horizontal gap region to be minimized for high acoustic pressure, while the vertical through-hole provides an alternative electrical pathway that maintains withstand voltage capability independently of the horizontal electrode spacing
Solution Approach 2:
The through-hole acts as an intermediary structure that decouples the relationship between electrode spacing and withstand voltage. By providing a separate vertical conduction path through the insulating film, it mediates between the conflicting requirements of small electrode distance (for power) and high withstand voltage (for reliability)
2Adaptability or versatility
If a thin membrane is used as the vibrating film to reduce mass and achieve broadband characteristics, then the broadband performance is improved, but the thickness fluctuation and warping increase, making it difficult to manufacture high-performance devices
Solution Approach 1:
The patent changes the structural parameters of the membrane system by adding the through-hole and modifying the electrode configuration. This allows the use of thin membranes for broadband performance while the through-hole structure provides stress relief and electrical stability that compensates for thickness variations, enabling manufacturing of high-performance devices
3Reliability
If through wiring is formed in the membrane to reduce fatigue from upper electrode stress, then the fatigue resistance is improved, but it becomes difficult to form thin films and the bandwidth is likely to be narrow
Solution Approach 1:
The patent moves the wiring approach from the horizontal plane (through the membrane) to the vertical dimension (through-holes in the insulating film above the membrane). This vertical through-hole configuration provides stress relief for fatigue resistance while maintaining the membrane's thin-film structure intact, preserving broadband characteristics
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 the production of capacitance type transducers with improved withstand voltage and sensitivity, facilitating the creation of high-performance devices capable of transmitting and receiving ultrasound waves effectively.
Implementation Method 1
forming a conductor film on the insulating film including the through hole to electrically connect a conductor in the through hole and the second electrode to each other
Implementation Method 2
forming an etching hole to remove the sacrificial layer
Implementation Method 3
forming a sealing film configured to seal the etching hole
Implementation Method 4
a capacitance type transducer using such technology is being researched as an alternative to a piezoelectric element. With such a capacitance type transducer, an acoustic wave such as an ultrasound wave may be transmitted and received using vibrations of a vibrating film
Data Source
AI summary
A capacitance type transducer includes a plurality of cells each having a structure in which a vibrating film is supposed so as to be vibrated. The vibrating film includes: a second electrode formed so that a gap is interposed between the second electrode and a first electrode; and an insulating film formed on the second electrode. The capacitance transducer manufacturing method includes: forming a sacrificial layer on the first electrode; forming a layer including a vibrating film on the sacrificial layer; forming an etching hole to remove the sacrificial layer; and forming a sealing film for sealing the etching hole. Before forming the etching hole to remove the sacrificial layer, a through hole is formed in an insulating film on the second electrode, and a conductor film is formed on the insulating film having the through hole to electrically connect a conductor in the through hole and the second electrode.