PCB EMI Shield Thru-Hole Latching Mechanism
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Solution Overview
Problem
Existing board-level shields face challenges in achieving adequate contact and good solder joints on printed circuit boards due to issues like part flatness, twist, and dynamic movement during solder reflow, especially in applications with thermal interface materials, making it difficult to fixture the shields effectively.
Innovation Solution
The introduction of thru-hole locking or latching mechanisms in single-piece or frame portions of board-level shields, which include protruding legs or latching members that align with PCB holes and pivot to engage the substrate, ensuring mechanical attachment and improved co-planarity for better solder joint formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional shielding methods are used without latching mechanisms, then the shielding structure is simple, but the contact adequacy and solder joint quality are insufficient
Solution Approach 1:
The latching members are designed to pivot from an initial position to a latched position, transforming from a static structure to a dynamic one. This movement allows the shielding apparatus to adapt to PCB variations and achieve adequate contact, resolving the contradiction between structural simplicity and contact quality.
Solution Approach 2:
The shielding apparatus is divided into separate functional components: the shield body and the latching members. This segmentation allows the latching mechanism to independently address contact adequacy while keeping the overall design manageable, resolving the contradiction between manufacturing precision and device complexity.
2Strength
If shields are mechanically attached to PCBs without latching mechanisms, then the attachment method is simple, but the retention force and secure attachment are insufficient
Solution Approach 1:
The latching members pivot to engage with the PCB, creating a mechanical lock that provides strong retention force. This dynamic action transforms a simple attachment concept into a secure mechanical connection, resolving the contradiction between retention strength and mechanism complexity.
Solution Approach 2:
The latching members act as intermediary elements between the shielding apparatus and the PCB. They provide the mechanical interface that achieves secure attachment, resolving the contradiction by introducing a specialized component that handles the retention function separately from the shield body.
3Ease of manufacture
If shields are attached during solder reflow, then the manufacturing process is simple, but the dynamic movement during reflow prevents adequate contact
Solution Approach 1:
The latching mechanism is designed to remain in the latched position during solder reflow, maintaining adequate contact despite thermal expansion and dynamic movement. This dynamic capability allows the shield to adapt to reflow conditions while preserving contact quality, resolving the contradiction between manufacturing simplicity and contact precision.
4Manufacturing precision
If thicker solder paste is used to compensate for poor contact, then the contact issue is masked, but the solder paste thickness cannot be reduced
Solution Approach 1:
The latching members establish adequate contact and co-planarity before the soldering process begins. This preliminary action ensures that the shielding apparatus is properly positioned and secured, allowing for reduced solder paste thickness since the mechanical attachment provides the necessary contact rather than relying on thick solder paste to compensate for positioning issues.
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 provides a reliable method for mechanically attaching shields to PCBs, ensuring good contact and co-planarity, allowing for reduced solder paste thickness and improved manufacturing simplicity, while also acting as an electrical conductive path, with high retention force for secure attachment.
Implementation Method 1
the latching members are configured to be insertable into the corresponding one or more holes in the substrate... the latching members may be engaged with the substrate to mechanically attach the EMI shielding apparatus to the substrate
Implementation Method 2
electrically conducting (and sometimes magnetically conducting) material is interposed between the two portions of the electronic circuitry for absorbing and/or reflecting EMI energy
Data Source
AI summary
Disclosed herein are exemplary embodiments of EMI shielding apparatus (e.g., one-piece shields, multi-piece shields, frames, etc.) having one or more latching members insertable into openings or holes in a substrate (e.g., printed circuit board, etc.) and engagable to the substrate. The engagement of the latching members with the substrate mechanically attaches the EMI shielding apparatus to the substrate.