EMI Shielding Membrane Keyboard for Enclosure Openings
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Solution Overview
Problem
Existing solutions for electromagnetic interference (EMI) containment in enclosures, such as server racks and cabinets, often require separate shielding components and lack functional integration, posing design challenges and increased costs.
Innovation Solution
A functional EMI containment assembly combining a membrane with a printed circuit board, featuring a metal foil layer and conductive adhesive, which acts as both an EMI shield and a tactile switch interface, allowing for seamless integration and enhanced visibility of LEDs through a domed lens element design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If separate shielding components are used for EMI containment, then EMI shielding effectiveness is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple functions into a single membrane assembly: the membrane includes both EMI shielding layers (conductive adhesive, foil layer) and operational elements (tactile switches, LED indicators, translucent overlay) integrated into one unified structure that can be applied over the enclosure opening, eliminating the need for separate shielding components
Solution Approach 2:
The membrane assembly serves multiple functions simultaneously: it provides EMI containment through conductive and foil layers, enables user input through tactile switches, provides visual feedback through LEDs with domed lenses for enhanced visibility, and maintains enclosure integrity - all within a single multi-functional component
2Ease of manufacture
If functional elements are integrated into the EMI shield, then ease of manufacture is improved, but EMI containment effectiveness may worsen
Solution Approach 1:
The membrane employs different materials and structures in different regions: conductive adhesive and foil layers for EMI shielding in areas requiring containment, while incorporating translucent material and domed lenses only in areas where LED visibility is needed, and tactile switches only where user input is required - each region optimized for its specific function without compromising overall EMI performance
Solution Approach 2:
The membrane is constructed as a composite structure with multiple layers including conductive adhesive, foil layer, switch elements, and translucent material - each layer contributes specific properties (EMI shielding, mechanical support, user interaction, light transmission) while working together to maintain overall EMI containment effectiveness
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 assembly provides effective EMI containment while functioning as a membrane keyboard, reducing the need for additional shielding components and enhancing visibility of indicators, thus addressing the need for cost-effective and functional EMI management in electronic enclosures.
Implementation Method 1
The materials chosen for the layers of the membrane also allow the membrane to act as an EMI shield and/or to provide EMI containment. In one embodiment, the membrane includes a metal foil layer that lays behind or abuts an adjacent layer that is formed of a conductive material such as a conductive adhesive. The combination of the foil and conductive layers of the membrane acts to provide a shield or plug for EMI.
Implementation Method 2
This may include providing an air gap between the LEDs on the circuit board (e.g., a PCA) and the first layer of the membrane because this air gap provides more uniform spreading of the emitted light onto the membrane's first layer
Implementation Method 3
One or more of the switches may take the form of a dome switch that has collapsing action (e.g., amount of travel), and the thickness of the layers of the membrane placed on top of the front of the circuit board is matched to the chosen dome switch to allow a proper amount of travel.
Data Source
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AI summary
A functional EMI containment plug or assembly useful to block an opening or hole in an electronics cabinet or enclosure to provide EMI containment. Functionality is achieved by combining a membrane with a circuit board. The EMC assembly functions as a circuit board-based membrane keyboard, which includes tactile switches a user can press to actuate a circuit board function. The switches may be a dome switch with collapsing action (e.g., amount of travel), and the thickness of the membrane layers placed on top of the front of the circuit board is matched to the chosen dome switch to allow a proper amount of travel. The layers of the membrane act as an EMI shield. In one embodiment, the membrane includes a metal foil layer and a conductive material layer, and the combination of foil and conductive layers of the membrane provide a shield for EMI.