EMI Shielding Structure With Segmented Dam And Top Layer
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Solution Overview
Problem
Current EMI shielding structures face limitations in miniaturization due to the thickness of shield cans and air gaps, which hinder heat dissipation and reduce EMI shielding effectiveness, especially in high-density electronic component mounting where narrow gaps between components make it difficult to form shielding dams with the required width-to-height ratio.
Innovation Solution
The proposed EMI shielding structure involves forming a conductive shielding dam along the side surface of an insulation molding member with a high width-to-height ratio, using a nozzle to discharge conductive material, and applying a liquid sealant to prevent material leakage between the mold and PCB, allowing for efficient shielding and heat dissipation while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shield can with constant thickness is used to maintain shape and prevent short circuits, then EMI shielding effectiveness is improved, but the height of the shield can cannot be reduced, hindering miniaturization
Solution Approach 1:
The shielding structure is divided into multiple segments: a shielding dam with first shielding layer, an insulation molding member, and a top shielding layer. This segmentation allows each component to perform its specific function optimally while reducing the overall height compared to a single thick shield can.
Solution Approach 2:
The shielding function is extended from a vertical wall structure (shield can) to include horizontal coverage at the top surface. The top shielding layer provides EMI protection in the horizontal dimension, allowing the vertical height to be reduced while maintaining overall shielding effectiveness.
2Temperature
If air vents are formed on the shield can to emit heat smoothly, then heat dissipation is improved, but electromagnetic waves leak through the vents, reducing EMI shielding effect
Solution Approach 1:
The insulation molding member acts as an intermediary between the circuit elements and the external environment. It provides thermal pathways for heat dissipation while maintaining EMI shielding integrity, replacing the need for air vents that would compromise shielding.
Solution Approach 2:
The insulation molding member functions as a flexible shielding structure that can incorporate thermal management features without compromising EMI protection. Unlike rigid shield cans requiring vents, this flexible structure allows integrated heat dissipation pathways.
3Volume of moving object
If circuit elements are high density mounted with narrow gaps, then device miniaturization is improved, but it becomes difficult to manufacture shielding dams with required width to height ratio
Solution Approach 1:
The manual or mechanical formation of shielding dams is replaced with a coating process using a nozzle. This substitution enables precise application of conductive material in narrow gaps between high-density circuit elements, achieving the required width-to-height ratio that is difficult to obtain with traditional mechanical methods.
4Reliability
If insulation material is injected into a mold to form insulation molding member, then EMI shielding and insulation are improved, but material may leak between the mold and PCB
Solution Approach 1:
A liquid sealant is applied to the mold surface before injecting the insulation material. This preliminary sealing action prevents material leakage during injection while allowing complete filling of the mold cavity, ensuring both EMI shielding effectiveness and material efficiency.
Data Source
AI summary
An electromagnetic interference (EMI) shielding structure and a method for manufacturing are provided. The EMI shielding structure includes a printed circuit board (PCB) on which a plurality of elements are mounted, an insulation molding member configured to cover the plurality of elements, a conductive shielding dam formed along a side surface of the insulation molding member, and a conductive shielding member formed on a top surface of the insulation molding member.