Backplateless Silicon Microphone Bonding Wire Impact Protection
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Solution Overview
Problem
Existing silicon microphones without a dedicated backplate face challenges in preventing breakage from strong impacts due to large diaphragm movements, and their fabrication processes are often complicated by stopper components that can cause compatibility issues.
Innovation Solution
A backplateless silicon microphone design featuring a diaphragm suspended over a backside hole with a perforated spring and anchors, where the spring is held by rigid pads on a dielectric layer, allowing for out-plane flexibility and in-plane stress release, and crossed bonding wires are used to restrict diaphragm movement and prevent breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stopper components are added to restrict large diaphragm movements, then impact resistance is improved, but device complexity and fabrication complexity increase
Solution Approach 1:
The patent removes the dedicated backplate component from the microphone structure, extracting the problematic element that caused compatibility issues with silicon membranes. The backplateless design eliminates the need for stopper components while maintaining impact resistance through the bonding wire reinforcement strategy.
Solution Approach 2:
The bonding wires are installed during the fabrication process before final assembly, creating a preliminary reinforcement structure that prevents breakage from large diaphragm movements. This preliminary action ensures impact protection is built into the structure rather than added as a separate component.
2Reliability
If stopper components are added to prevent breakage, then reliability is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the function of movement restriction into the existing bonding wire structure and diaphragm design. Instead of adding separate stopper components, the bonding wires themselves serve to limit excessive diaphragm movement, combining multiple functions into existing elements and simplifying the manufacturing process.
Solution Approach 2:
The bonding wires serve multiple functions: providing electrical connections and simultaneously acting as structural reinforcement to prevent breakage from large movements. This multi-functionality eliminates the need for dedicated stopper components, reducing fabrication complexity while maintaining reliability.
3Stability of the object's composition
If a dedicated backplate is used to support the diaphragm, then structural stability is improved, but device complexity and compatibility issues arise
Solution Approach 1:
The patent extracts and removes the dedicated backplate component from the microphone assembly. The backplateless design achieves structural stability through the spring-loaded diaphragm support and bonding wire reinforcement, eliminating compatibility issues between the backplate and silicon membrane while reducing overall device complexity.
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 design enhances impact resistance without adding complexity to the fabrication process and prevents device breakage by allowing controlled motion of the diaphragm and spring while maintaining acoustic performance.
Implementation Method 1
a spring surrounds the perforated plates and diaphragm. The spring is held to the substrate through a plurality of anchors
Implementation Method 2
crossed bonding wires are used to restrict excessive motion and prevent breakage
Data Source
AI summary
A backplateless silicon microphone and a wire protection method for improved impact resistance are disclosed. A circular diaphragm is surrounded by a circular spring having a plurality of slots and perforations to facilitate air damping reduction, release of in-plane stress, and improve out-plane flexibility. Anchored at a substrate, the circular spring holds the silicon microphone suspended over a backside hole in the substrate but allows the diaphragm to vibrate perpendicular to the substrate. A microphone variable capacitor is formed between the perforated spring and substrate. Slot size is minimized to prevent particles from entering an underlying air gap. A plurality of “n” bonding pads near the outer edge of the circular spring are connected by “n/2” bonding wires that serve as a stopper to restrict an upward motion of the diaphragm. The bonding wires may cross each other to enable lower loop height for more effective resistance to impact.