PCB-Based MEMS Package with Electro-Plated Diaphragm
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Solution Overview
Problem
The high manufacture cost of conventional MEMS packages due to photo-mask, photolithography, and etching processes, and the need for a smaller gap between metallic diaphragm and electrode for improved performance.
Innovation Solution
A MEMS package design incorporating a first board, a second board, and a laminate material, with metallic diaphragm and electrode formed using electro-plating processes, and a third board acting as an electromagnetic shield, all manufactured using PCB processes to reduce costs and achieve a smaller gap between the diaphragm and electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photo-mask, photolithography and etching processes are used to form the capacitor and operation element on the silicon substrate, then the MEMS package can be manufactured with precise component placement, but the manufacture cost becomes high
Solution Approach 1:
The patent merges the capacitor and operation element fabrication into a single PCB manufacturing process. The capacitor is formed by electro-plating metallic layers directly on the PCB substrate, while the operation element is created by drilling and plating through-holes, eliminating the need for separate photolithography and etching steps. This integration maintains manufacturing precision while significantly reducing manufacture cost.
Solution Approach 2:
The patent replaces the photo-mask and photolithography system with an electro-plating system. Instead of using optical methods to deposit and pattern metallic layers, the invention uses electro-plating to directly form the capacitor metallic layers and through-hole plating on the PCB substrate, substituting complex optical-mechanical systems with a simpler electrochemical process.
2Manufacturing precision
If the electro-plating layers of the metallic diaphragm and metallic electrode are made thicker, then the gap between the metallic diaphragm and the metallic electrode becomes smaller, but the manufacturing complexity increases
Solution Approach 1:
The patent controls the gap between the metallic diaphragm and metallic electrode by adjusting the electro-plating parameters, specifically the plating thickness. By precisely controlling the electro-plating process parameters (current density, plating time, electrolyte composition), the invention achieves accurate gap control without increasing device complexity. The thicker electro-plating layers directly result in smaller gaps, providing a simple parameter-based control mechanism.
3Object-affected harmful factors
If the third board is designed with upper and lower metallic layers on its surfaces, then the electro-magnetic shielding performance is improved, but the device complexity increases
Solution Approach 1:
The third PCB board serves multiple functions: it provides structural support as part of the package assembly, offers electrical connectivity through its metallic layers and via-holes, and provides electro-magnetic shielding through its upper and lower metallic layers. By integrating these multiple functions into a single component, the invention improves electro-magnetic shielding performance without significantly increasing 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 PCB-manufactured MEMS package reduces production costs and achieves a smaller gap between the metallic diaphragm and electrode, enhancing performance and allowing for effective calculation of vibration signals through capacitance variation.
Implementation Method 1
metallic diaphragm and electrode formed using electro-plating processes
Implementation Method 2
a sensing unit is formed by the metallic diaphragm, the hollow portion and the metallic electrode... allowing for effective calculation of vibration signals through capacitance variation
Data Source
AI summary
A MEMS package includes a first board, a second board and a laminate material. The first board includes a lower metallic trace, a metallic diaphragm and a through opening. The lower metallic trace is located on the lower surface of the first board, and the metallic diaphragm is disposed on the lower metallic trace. The second board includes an upper metallic trace and a metallic electrode. The upper metallic trace is located on the upper surface of the second board, the metallic electrode is disposed on the upper metallic trace, and the metallic electrode is corresponding to the metallic diaphragm. The laminate material is disposed between the lower and upper metallic traces, and includes a hollow portion for accommodating the metallic electrode and metallic diaphragm, wherein a sensing unit is formed by the metallic electrode, the hollow portion and the metallic diaphragm, and is corresponding to the through opening.