Internal Wire Fence Shielding for PCB EMI Isolation
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Solution Overview
Problem
Conventional external shields in electronic modules fail to provide effective shielding against internally generated electromagnetic interference (EMI), which can exacerbate noise issues due to their inability to shield individual components within the module, and existing internal shielding methods are inefficient and difficult to fabricate.
Innovation Solution
The implementation of internal wire fence shielding, where multiple wire loops are connected to wire pads on a printed circuit board (PCB) and filled with conductive material, providing lateral shielding and protection from both internal and external electromagnetic radiation, along with a top conductive layer and side conductive layers for enhanced shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If external shields are used to protect against external electromagnetic radiation, then protection against external electromagnetic radiation is improved, but shielding against internally generated electromagnetic radiation deteriorates
Solution Approach 1:
The shield is divided into two distinct parts: an external shield for protecting against external electromagnetic radiation and an internal wire fence for shielding against internally generated electromagnetic radiation. This segmentation allows each component to be optimized for its specific function, resolving the contradiction between external and internal shielding capabilities.
Solution Approach 2:
The internal wire fence acts as an intermediary shielding structure positioned between the electronic components and the external shield. It mediates the electromagnetic interference by blocking internal radiation before it can interact with the external shield, thereby solving the problem of internal electromagnetic radiation shielding.
2Object-generated harmful factors
If conventional internal shields are implemented, then internal electromagnetic shielding is improved, but fabrication efficiency and cost deteriorate
Solution Approach 1:
The patent replaces complex mechanical shielding structures with a simplified wire fence configuration that can be easily integrated into the PCB fabrication process. The wire fence is formed using standard PCB manufacturing techniques, eliminating the need for separate, complex shielding fabrication steps and thereby improving production efficiency.
Solution Approach 2:
The internal shield is implemented as a wire fence with specific geometric parameters (wire diameter, spacing, height) that can be easily controlled during PCB fabrication. By optimizing these parameters, the shield provides effective electromagnetic protection while being cost-effective and easy to manufacture using existing fabrication processes.
3Object-generated harmful factors
If wire fences are used for internal shielding, then internal electromagnetic shielding is improved, but contact error between wire and PCB surface increases
Solution Approach 1:
The wire fence is positioned and secured to the PCB surface in advance during the PCB fabrication process, before the module assembly is completed. This preliminary action ensures proper contact and positioning, minimizing contact errors while maintaining effective shielding performance.
Solution Approach 2:
A conductive adhesive or mounting structure serves as an intermediary between the wire fence and the PCB surface. This intermediary element ensures reliable electrical contact and mechanical attachment, reducing contact errors while allowing the wire fence to maintain its shielding function.
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 solution effectively reduces electromagnetic interference by providing efficient internal shielding, allowing for closer component placement, reducing module size, and improving fabrication efficiency and cost-effectiveness compared to conventional methods.
Implementation Method 1
wire fence including multiple wire loops respectively connected to each of the at least one wire pad; a mold compound disposed over the PCB, the SMT component and the first wire fence, the mold compound defining multiple holes extending partially through the mold compound, from a top surface of the mold compound to top-edges of the multiple wire loops, respectively, where a conductive material fills the multiple holes
Implementation Method 2
a top conductive layer disposed over the top surface of the mold compound, and in electrical contact with the conductive material filling the holes
Data Source
AI summary
A module includes a PCB including a substrate, a component pad and at least one wire pad, an SMT component mounted to a component pad, a wire fence, a mold compound and a top conductive layer. Each wire pad is connected to ground by a corresponding via extending through the substrate, and the wire fence includes wire loops connected to each wire pad. The mold compound is disposed over the PCB, the SMT component and the wire fence, and defines multiple holes extending partially through the mold compound to top-edges of the wire loops, respectively, where a conductive material fills the holes. The top conductive layer is disposed over the mold compound, and is in electrical contact with the conductive material filling the holes. The wire fence, the conductive material, and the top conductive layer provide shielding of the SMT component from electromagnetic radiation.