Staggered Shield Tabs for PCB EMI Reduction
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Solution Overview
Problem
There is a need to maintain electromagnetic shielding in compact electronic devices like mobile computing devices while reducing the size of circuit board assemblies and increasing component density, as existing shielding methods do not efficiently utilize the space on both sides of the printed circuit board.
Innovation Solution
The implementation of a dual-shield system where conductive tabs on a first shield are staggered with those on a second shield, allowing for efficient electromagnetic interference (EMI) and radio frequency (RF) shielding by positioning shields on both sides of the circuit board and coupling them to the side surfaces, thereby increasing component density without compromising shielding effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shields are mounted on both sides of the circuit board with tabs coupled to side surfaces, then electromagnetic shielding effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent transitions from traditional top-bottom shield mounting to utilizing the side surfaces of the circuit board for tab attachment. This dimensional change allows shields to be positioned on both sides of the board while anchoring tabs to the vertical side surfaces, creating a three-dimensional mounting configuration that improves shielding effectiveness without proportionally increasing complexity
Solution Approach 2:
The patent employs asymmetric tab positioning where tabs on opposite shields are staggered rather than aligned. This asymmetric arrangement prevents tab overlap and simplifies the mounting process while maintaining effective electromagnetic shielding, resolving the contradiction between shielding performance and structural complexity
2Quantity of substance
If component density is increased on the circuit board, then device size is reduced, but electromagnetic shielding effectiveness deteriorates
Solution Approach 1:
By mounting shield tabs to the side surfaces of the circuit board rather than consuming top or bottom surface area, the patent enables increased component density on the board surfaces while maintaining effective shielding. This utilizes the vertical dimension for shielding attachment, freeing up horizontal space for additional components
3Manufacturing precision
If shields are coupled to side surfaces with staggered tabs, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The staggered asymmetric tab arrangement simplifies manufacturing by preventing tab overlap and interference during the assembly process. While the tabs are positioned asymmetrically, this actually improves ease of manufacture by allowing sequential placement without complex alignment requirements, while still achieving precise final positioning
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 approach allows for increased component density and reduced manufacturing costs by utilizing side surfaces of the circuit board for shielding, minimizing the risk of short circuits and excess solder volume, while maintaining effective EMI and RF shielding.
Implementation Method 1
Conductive shields may be used to provide electromagnetic interference (EMI) and radio frequency (RF) shielding to reduce the coupling of radio waves, electromagnetic fields and electrostatic fields generated by the various components in the device
Data Source
AI summary
A circuit board assembly includes a first shield positioned over a top surface of a printed circuit board and a second shield positioned over a bottom surface. The first and second shields include conductive tabs which are coupled to a first side surface of the circuit board, wherein the tabs of the first shield are generally interposed or staggered with the tabs of the second shield.