Electret Microphone Direct Contact Substrate Elimination Bonding Wire
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Solution Overview
Problem
Conventional electret condenser microphones face challenges in miniaturization due to electric losses from bonding wires and degraded high-frequency characteristics resulting from reduced back air chamber size.
Innovation Solution
An electret condenser microphone design that establishes mechanical contact between the substrate and electret condenser, eliminating the need for bonding wires, and utilizes the internal case region as a back air chamber to enhance high-frequency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding wire is used to connect condenser and drive circuit element, then electrical connection is established, but electric loss occurs and high-frequency characteristic degrades
Solution Approach 1:
The patent extracts and eliminates the bonding wire from the system by establishing direct mechanical contact between the electret condenser and substrate. The electret condenser is mounted directly on the substrate with its lower electrode forming electrical contact with the substrate, removing the intermediate bonding wire that causes energy loss and high-frequency degradation.
Solution Approach 2:
The patent merges the electrical connection function with the mechanical mounting structure. The substrate serves dual purposes: as the mechanical support for the electret condenser and as the electrical connection path to the drive circuit element, eliminating the need for separate bonding wire connections.
2Volume of moving object
If condenser size is reduced for miniaturization, then device size decreases, but back air chamber size is also reduced causing high-frequency characteristic degradation
Solution Approach 1:
The patent extends the back air chamber into the vertical dimension by utilizing the case depth. The back air chamber is formed by the cavity in the substrate and the internal region of the case, creating a three-dimensional air volume that maintains adequate size even when the horizontal dimensions are reduced for miniaturization.
Solution Approach 2:
The case serves multiple functions: it provides mechanical protection for the electret condenser and drive circuit element, and simultaneously forms part of the back air chamber structure. The internal region of the case contributes to the back air chamber volume, allowing the case to serve both structural and acoustic functions.
3Loss of energy
If mechanical contact is used to connect substrate and electret condenser, then electrical connection is established without bonding wire, but manufacturing precision requirements increase
Solution Approach 1:
The electret condenser structure itself provides the mechanical contact and electrical connection function. The lower electrode of the electret condenser is designed to directly contact the substrate, using the condenser's own structure to establish both mechanical support and electrical connection without requiring separate alignment procedures or additional components.
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 design suppresses parasitic capacitance and noise, improving high-frequency characteristics while allowing for miniaturization without compromising performance.
Implementation Method 1
an electret condenser connected to one face of the substrate so as to close the opening
Data Source
AI summary
An electret condenser microphone includes: a substrate 13 in which an opening 25 is formed; an electret condenser 50 connected to one face of the substrate 13 so as to close the opening 25 and having an acoustic hole 12 and a cavity 2; a drive circuit element 15 connected to the one face of the substrate 13; and a case 17 mounted over the substrate 13 so as to cover the electret condenser 50 and the drive circuit element 15. Electric contact is established at a joint part between the electret condenser 50 and the substrate 13. The acoustic hole 12 communicates with an external space through the opening 25. The cavity 2 and an internal region of the case 17 serve as a back air chamber for the electret condenser 50.