Conformal Shield for Circuit Board EMI Reduction
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Solution Overview
Problem
Conventional box-type RFI/EMI shields are bulky, consume space, and are difficult to re-test or rework, as they are soldered onto circuit boards, making redesigns and repairs challenging, especially in compact electronic devices like cellular phones.
Innovation Solution
A conformal shield is formed by applying a dielectric coating to a circuit board, creating openings over contact pads, and depositing metallic layers to provide electrical connections, allowing for efficient RF and EM shielding without the bulk of traditional shields, enabling easy removal and reworking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If box-type shields are used for RFI/EMI shielding, then shielding performance is achieved, but device volume and weight increase significantly
Solution Approach 1:
The patent applies a thin conformal coating layer (dielectric material) directly onto the circuit board surface to provide RFI/EMI shielding. This thin-film approach replaces bulky box-type shields, achieving the required shielding performance while minimizing the increase in device volume. The coating conformally follows the board contours and provides effective shielding without adding significant thickness.
Solution Approach 2:
The invention extracts only the essential shielding function from the traditional box-type shield structure. Instead of using a complete enclosed metal box, the patent applies a thin conformal coating that provides the necessary electromagnetic shielding while eliminating the excess volume occupied by the box structure's walls and air gaps.
2Strength
If box-type shields are soldered onto the circuit board, then mechanical attachment is achieved, but re-testing and rework become extremely difficult
Solution Approach 1:
The patent replaces the mechanical soldering attachment system with a chemical/conformal coating attachment system. The dielectric coating is applied conformally over the circuit board and components, providing mechanical attachment through adhesion rather than solder joints. This allows the shielding to be removed and reapplied without the difficulty of desoldering, enabling easy re-testing and rework.
Solution Approach 2:
The conformal coating provides a dynamic, flexible attachment method that allows for removal and reapplication. Unlike rigid soldered connections, the coating can be peeled or removed to access underlying components for rework, then reapplied to restore shielding, providing operational flexibility throughout the product lifecycle.
3Object-affected harmful factors
If conformal coating is applied to circuit board, then shielding performance is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent merges the RFI/EMI shielding function with the conformal coating process. By applying a dielectric conformal coating that provides both environmental protection and electromagnetic shielding in a single layer, the manufacturing process achieves multiple functions simultaneously. This integration reduces the number of separate manufacturing steps compared to applying shielding as a separate operation.
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 conformal shield effectively reduces RF and EM interference while allowing for post-assembly testing and easy repair of circuit boards, contributing to product miniaturization and cost reduction by eliminating the need for bulky metal shields and soldering.
Implementation Method 1
depositing a first metallic layer over the insulating coating
Implementation Method 2
depositing a first and second metallic layers over the insulating coating
Implementation Method 3
depositing a first metallic layer over the insulating coating and in each of the plurality of openings
Data Source
AI summary
A system and method for providing shielding to an electrical system is disclosed. A conformal shield is formed by applying a conformal insulating coating to an electrical system. A plurality of openings are formed in the insulating coating at desired locations and a first metallic layer is deposited over the insulating coating and in each of the plurality of openings, the first metallic layer being electrically connected with the circuit board at the desired locations. A second metallic layer is then deposited onto the first metallic layer to increase a thickness of the metallic layers.