Hybrid Shielding Structure for Overmolded PCBs
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Solution Overview
Problem
Existing electromagnetic shielding techniques for overmolded printed circuit boards (PCBs) face challenges in balancing electromagnetic shielding with the need for molding compound flow, often requiring expensive and time-consuming processes, and can cause PCB warping or cracking due to long conductive trenches.
Innovation Solution
A hybrid electromagnetic shielding structure combining conductive fences and trenches, where conductive fences with optimized openings allow for mold flow while providing shielding, and are applied using surface mount technology to reduce manufacturing time and prevent warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If long conductive trenches are used for electromagnetic shielding, then shielding effectiveness is improved, but PCB warping and cracking occur during overmolding
Solution Approach 1:
The patent divides the continuous conductive trench into discrete conductive fence segments spaced apart from each other. Each fence is a separate conductive element that provides electromagnetic shielding locally, but the spacing between fences prevents stress accumulation across the entire PCB, thereby preventing warping and cracking during overmolding while maintaining shielding effectiveness.
2Object-affected harmful factors
If conductive trenches are used for electromagnetic shielding, then shielding effectiveness is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent replaces the traditional mechanical process of filling trenches with conductive material (which requires precise trench formation, material deposition, and curing) with a simpler approach of using pre-formed conductive fence elements that can be directly positioned and secured on the PCB. This substitution eliminates the time-consuming trench filling process while achieving equivalent shielding effectiveness.
3Object-affected harmful factors
If solid conductive fences are used without openings, then electromagnetic shielding is improved, but molding compound flow is restricted
Solution Approach 1:
The patent applies different properties to different parts of the conductive fence structure. The fences are designed with openings or gaps at specific locations that allow molding compound to flow through, while maintaining continuous conductive paths in other areas for electromagnetic shielding. This local variation in structure enables both functions to coexist effectively.
4Ease of manufacture
If conductive fences with openings are used, then mold flow is optimized, but shielding effectiveness may be reduced
Solution Approach 1:
The patent uses conductive fences with openings that provide sufficient shielding for the application requirements while maintaining adequate openings for mold flow. The fence structures are designed to provide partial shielding (not complete blocking) which is sufficient for protecting sensitive components while allowing the molding process to proceed effectively. This partial action approach balances both competing requirements.
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 hybrid structure effectively shields electronic components from electromagnetic radiation, optimizes mold flow, and reduces manufacturing time and costs by using conductive fences instead of trenches, maintaining PCB flatness and improving shielding effectiveness.
Implementation Method 1
the conductive trenches and the conductive fences provide an electromagnetic shield for at least a portion of the electronic components of the PCB
Data Source
AI summary
The disclosed hybrid shielding structure may include a printed circuit board (PCB) that is to be overmolded with at least a portion of molding compound. The PCB may include various electronic components disposed thereon. The hybrid shielding structure may also include conductive trenches and conductive fences that are disposed on the PCB. The conductive trenches and the conductive fences may provide an electromagnetic shield for at least a portion of the electronic components of the PCB. The hybrid shielding structure may further include a conformal shielding and a PCB ground flood and ground layers. Various other systems, electronic devices, apparatuses, and methods of manufacturing are also disclosed.