Multi-layer EMI Shield on PCB Reduces Z-height
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Solution Overview
Problem
Printed circuit boards (PCBs) face challenges in electromagnetic interference (EMI) shielding, requiring additional routing layers that increase cost and Z-height, and existing shielding solutions are costly, add manual processing steps, and are not 100% leakage proof.
Innovation Solution
A multi-layer EMI shield with a thin metallic layer, conductive adhesive, and electrically insulating base layer is applied pre-SMT, reducing Z-height and providing high-performance shielding up to 99% by being mechanically and electrically coupled to ground pads through the solder resist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional metal shield soldering is used for EMI shielding, then EMI shielding performance is improved, but manufacturing cost and processing complexity increase
Solution Approach 1:
The EMI shield is integrated into the PCB structure during the fabrication process itself, rather than being added as a separate post-SMT component. The shield is formed as part of the multilayer board structure, eliminating the need for separate metal shield soldering operations and reducing manufacturing complexity while maintaining effective EMI shielding.
Solution Approach 2:
The EMI shielding function is merged with the PCB ground planes and routing layers. By integrating the shield into the multilayer structure using existing conductive layers and ground planes, the patent combines multiple functions (signal routing, grounding, and EMI shielding) into a single integrated structure, reducing additional manufacturing steps and costs.
2Object-affected harmful factors
If additional shielding layers are added to provide grounding to outer EMI layers, then EMI shielding performance is improved, but Z-height of the system increases
Solution Approach 1:
The outer routing layers of the PCB are designed to serve multiple functions simultaneously: signal routing, EMI shielding, and grounding. By making the routing layers universal rather than dedicated to single functions, the patent eliminates the need for separate shielding layers, thereby reducing Z-height while maintaining effective EMI shielding performance.
Solution Approach 2:
The EMI shielding capability is distributed locally across the multilayer structure rather than requiring a separate dedicated shield layer. Each routing layer and ground plane is designed with local EMI shielding properties, allowing the system to achieve overall shielding effectiveness without increasing Z-height through additional centralized shielding layers.
3Object-affected harmful factors
If post surface mount technology processes are used for EMI shielding, then EMI shielding can be implemented, but manufacturing cost and manual processing steps increase
Solution Approach 1:
The EMI shield is formed during the preliminary PCB fabrication process rather than being added as a post-SMT component. The multilayer structure is built with EMI shielding capabilities integrated into the board fabrication sequence, eliminating the need for separate post-SMT shielding applications and associated manual processing steps.
Solution Approach 2:
The PCB structure itself provides the EMI shielding function through its multilayer design, rather than requiring separate shielding components to be applied. The routing layers and ground planes serve self-contained EMI shielding roles, making the system self-sufficient and eliminating the need for additional manual shielding processing steps.
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 significantly reduces the Z-height of PCBs, eliminates additional processing steps, and achieves high EMI shielding effectiveness, allowing for routing of high-speed signals and high-switching power shapes on outer layers with reduced material costs.
Implementation Method 1
a conductive adhesive over the first surface of the metallic layer... the conductive adhesive electrically couples the metallic layer to one or more electrically grounded conductive features
Implementation Method 2
A multi-layer EMI shield with a thin metallic layer, conductive adhesive, and electrically insulating base layer is applied pre-SMT, reducing Z-height and providing high-performance shielding up to 99%
Data Source
AI summary
Embodiments disclosed herein include a printed circuit board (PCB). In an embodiment, the PCB comprises a core and routing layers over and under the core. In an embodiment, a multi-layer shield is over at least one of the routing layers. In an embodiment, the multi-layer shield comprises a metallic layer with a first surface and a second surface opposite from the first surface, and a conductive adhesive over the first surface of the metallic layer. In an embodiment, a base layer is over the second surface of the metallic layer, where the base layer is electrically insulating.