Optical Sensor Module EMI Shield Grounding for Low Leakage
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Solution Overview
Problem
Conventional EMI shielding methods for optical sensors, such as metal can shielding, increase the footprint of circuit boards, allow EM leakage, and fail to prevent internal crosstalk, while being costly and requiring complex assembly processes.
Innovation Solution
The method involves using an EMI shield with discrete or elongated grounding pads on the module substrate, conductive vias, and conductive coatings to create a robust connection with the module substrate, preventing EM leakage and crosstalk, and employing multi-part shields for comprehensive coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional metal can shielding is used, then EMI shielding coverage is provided, but the footprint of the circuit board increases
Solution Approach 1:
The EMI shield is divided into multiple discrete components (first EMI shield component, second EMI shield component, third EMI shield component) that can be selectively applied to different portions of the circuit board. This segmentation allows comprehensive EMI coverage while minimizing the overall footprint by only shielding specific areas rather than the entire board.
Solution Approach 2:
Instead of providing uniform EMI shielding across the entire circuit board, the patent applies shielding components locally to specific areas where EMI protection is most needed. The first EMI shield component covers the optical sensor, the second shields the circuit board edge, and the third shields specific circuit components, optimizing protection while reducing material usage and footprint.
2Object-affected harmful factors
If stamped metal sheet cans are used, then EMI shielding is provided, but the corner radius increases the footprint
Solution Approach 1:
The shield is segmented into multiple components with different geometries suited to specific locations. The first component is a substantially planar sheet for general coverage, the second is an L-shaped component for edge coverage, and the third is a substantially spherical component for rounded corners. This segmentation eliminates the need for large corner radii in stamped cans.
Solution Approach 2:
The patent employs a composite shielding approach using multiple materials and geometries: planar metal sheets, L-shaped metal components, and spherical metal components. This composite structure provides effective EMI shielding while adapting to the circuit board's geometry without requiring excessive material or increased footprint.
3Object-affected harmful factors
If multiple metal cans are used to cover irregularly shaped components, then comprehensive coverage is provided, but EM leakage points are introduced
Solution Approach 1:
The patent merges multiple shielding functions into an integrated multi-component system where the first, second, and third EMI shield components work together to provide continuous coverage. The components are positioned and configured to eliminate gaps and leakage points that would occur with separate, disconnected shields.
Solution Approach 2:
The use of substantially planar, L-shaped, and spherical components allows the shielding system to flexibly adapt to irregularly shaped circuit board areas. These thin-walled metal components can be configured to closely follow the contours of the circuit board and components, ensuring continuous coverage without rigid geometric constraints.
4Object-affected harmful factors
If circuit board level metal can shielding is used, then EMI shielding is provided, but internal EMI crosstalk between components is not prevented
Solution Approach 1:
The shielding system is segmented into multiple components that can be strategically positioned between different circuit components. The second EMI shield component specifically addresses circuit board edge emissions, while the third component shields specific high-frequency circuit areas, preventing internal crosstalk while maintaining external shielding.
Solution Approach 2:
The patent applies shielding with local quality by positioning specific EMI shield components at locations where internal crosstalk is most problematic. The L-shaped component shields edge circuits, the spherical component shields specific component areas, and the planar component provides general coverage, creating localized protection zones that prevent crosstalk between adjacent components.
5Object-affected harmful factors
If circuit board level shielding is used, then EMI protection is provided, but quality assurance costs and assembly complexity increase
Solution Approach 1:
The EMI shield is segmented into multiple discrete components that can be applied independently to different areas of the circuit board. This segmentation simplifies assembly by allowing each component to be installed separately using standard techniques, reducing the complexity of ensuring proper alignment and grounding of a single large shield.
Solution Approach 2:
The patent employs different geometric parameters for different shield components (planar, L-shaped, spherical) that are optimized for their specific locations. This parameter variation allows each component to be manufactured using standard processes and assembled using conventional techniques, reducing overall assembly complexity while maintaining effective EMI protection.
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 reduces EM leakage and crosstalk, minimizes footprint, and simplifies assembly, while maintaining effective EMI shielding without increasing costs.
Implementation Method 1
applying an adhesive to the module for adhering the EMI shield to the module
Implementation Method 2
applying conductive adhesive to the one elongated grounding pad to create a conductive connection between the module substrate and the EMI shield
Implementation Method 3
applying solder paste to the one elongated grounding pad to create a conductive connection between the module substrate and the EMI shield
Implementation Method 4
Electromagnetic interference shielding creates a Faraday cage effect which attenuates radiation of electromagnetic (EM) waves and/or prevents EM emissions from circuit components
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
Methods and systems for grounding of integrated external electromagnetic interference (EMI) shields are provided. A portion of a module substrate 102 protrudes on at least one side of the module 100A. The protruding portion of the module substrate comprises one or more grounding pads 103a...N to which the EMI shield 101 is grounded. The EMI shield may cover at least a portion of the thickness of the module substrate. The EMI shield may be comprised of one or more parts, which may be coupled to one another. The module substrate may include conductive vias. The EMI shield may include a sprayed and/or printed coating. The EMI shield may include a darkened coating.