Silicon Microphone EMI Shielding via Conductive Via Holes
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Solution Overview
Problem
Existing silicon-based microphone structures face challenges in providing effective electromagnetic interference shielding, maintaining low costs, and achieving minimized package size, as they often suffer from acoustic resonance and inadequate compactness in modern electronic devices.
Innovation Solution
A silicon-based microphone structure with a conductive layer covering the backside and via holes, combined with a solder ring or metal bump for electromagnetic interference shielding, and flip-chip mounting to reduce size and enhance shielding effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a cover with outer cup and inner cup is used for electromagnetic interference shielding, then electromagnetic interference shielding is improved, but acoustic resonance is generated in the chamber so that the operating frequency band becomes narrow
Solution Approach 1:
The patent removes the complex multi-cup cover structure and extracts only the essential shielding function. Instead of using a cover with outer cup and inner cup, the invention forms a conductive layer directly on the substrate and uses via holes to connect it to a ground plane, thereby eliminating the chamber that causes acoustic resonance while maintaining electromagnetic interference shielding effectiveness.
Solution Approach 2:
The patent introduces via holes as intermediary conductive pathways between the conductive layer on the substrate and the ground plane. These via holes serve as mediators that provide electromagnetic interference shielding without requiring a enclosed chamber structure, thus avoiding acoustic resonance issues while maintaining shielding effectiveness.
2Object-affected harmful factors
If a cover with outer cup and inner cup is used for electromagnetic interference shielding, then electromagnetic interference shielding is improved, but the size of the package cannot meet modern electronic device requirements for extreme compactness
Solution Approach 1:
The patent extracts the essential shielding function from the bulky cover structure and integrates it directly into the substrate through a conductive layer and via holes. This eliminates the need for a separate enclosed chamber, dramatically reducing package size while maintaining electromagnetic interference shielding capability.
Solution Approach 2:
The patent merges the electromagnetic interference shielding function with the substrate structure itself. By forming a conductive layer on the substrate and connecting it to ground through via holes, the shielding function is combined with the existing substrate, eliminating the need for additional cover structures and reducing overall package volume.
3Object-affected harmful factors
If lid and EMI shield are formed during assembly rather than in advance, then electromagnetic interference shielding is provided, but the production process becomes difficult and inconvenient
Solution Approach 1:
The patent performs preliminary actions by forming the conductive layer and via holes in the substrate before assembly. The conductive layer is patterned on the substrate and via holes are created and filled with conductive material in advance, so that when components are assembled, the electromagnetic interference shielding structure is already in place, simplifying the overall production process.
Solution Approach 2:
The substrate serves itself by having the conductive layer and via holes formed directly on it during substrate fabrication. This self-service approach integrates the EMI shielding structure creation into the substrate manufacturing process itself, eliminating the need for separate shielding formation steps during assembly.
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 electromagnetic interference and acoustic impedance, allowing for a broader operating frequency band while minimizing package size, thus meeting modern electronic device requirements for compactness and ease of production.
Implementation Method 1
a conductive layer 231, and a solder ring 130. The silicon-based microphone structure 200 has a backside and a via hole formed on the backside. The conductive layer 231 covers the backside and inner walls of the via hole 240. The solder ring 130 is attached to the silicon-based microphone structure 200 and electrically connected to the conductive layer 231.
Implementation Method 2
The via hole 240 is formed by dry etching. The via hole 240 is dimple-shaped. The conductive layer 231 is formed by sputtering, evaporation, or electroplating.
Data Source
AI summary
A silicon-based microphone structure, flip-chip mounted a substrate, has a backside and a via hole formed on the backside. A conductive layer covers the backside and the inner walls of the via hole. A solder ring is attached to the silicon-based microphone structure and electrically connected to the conductive layer.