Leadless Semiconductor Package Shielding With Grounded Full Enclosure
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Solution Overview
Problem
Existing semiconductor devices, particularly leadless designs like QFN packages, face challenges in achieving complete electromagnetic (EM) shielding, especially for high-sensitivity applications, with current solutions providing only partial shielding and high costs.
Innovation Solution
A full-enclosure EM shielding is achieved by combining a plated shield with a modified leadframe peripheral ring structure and grounding arrangement, involving cuts and metal plating to form a complete enclosure around the module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional partial shielding solutions are used, then manufacturing cost is reduced and device complexity is lowered, but electromagnetic shielding performance remains insufficient (maximum 30 dB)
Solution Approach 1:
The patent combines multiple shielding elements (peripheral ring, signal leads, ground leads, and top plate) into an integrated full-enclosure shielding structure. The peripheral ring is electrically connected to ground leads, while signal leads are isolated from the peripheral ring through cutting, creating a unified shielding system that achieves complete EM protection rather than partial shielding.
Solution Approach 2:
The shielding structure is divided into distinct functional segments: the peripheral ring forming the base enclosure, ground leads providing electrical connection to ground, signal leads that are cut and isolated to prevent interference, and a top plate completing the enclosure. This segmentation allows each component to be optimized for its specific shielding function while working together as a complete system.
2Object-affected harmful factors
If custom-designed shielding plates and casings are used for specific PCB layouts, then EM shielding effectiveness is improved, but manufacturing cost increases significantly and reproducibility decreases
Solution Approach 1:
The patent creates a universal shielding structure where the peripheral ring, ground leads, and top plate form a standardized full-enclosure design that can be applied to various QFN packages and PCB layouts. The modular nature of the shielding elements allows them to be adapted to different applications without requiring custom-designed shielding plates for each specific layout, thereby reducing manufacturing cost and improving reproducibility while maintaining shielding effectiveness.
3Object-affected harmful factors
If the peripheral ring is cut to expose contact surfaces for plating, then complete EM shielding enclosure is achieved, but the structural integrity and electrical connection complexity increase
Solution Approach 1:
The peripheral ring is pre-cut to expose contact surfaces before the metal plating process is applied. This preliminary action ensures that the plating can make proper electrical contact with the peripheral ring, establishing reliable electrical connections for the shielding system before final assembly and testing.
Solution Approach 2:
Metal plating is introduced as an intermediary material that bridges the electrical connection between the peripheral ring and the shielding structure. The plating is applied to the exposed contact surfaces of the peripheral ring, creating a conductive pathway that ensures proper electrical grounding and shielding effectiveness without compromising the structural integrity of the leadframe.
4Object-affected harmful factors
If signal leads are severed from the peripheral ring, then EM shielding completeness is improved, but manufacturing process complexity and the number of processing steps increase
Solution Approach 1:
Signal leads are selectively cut and separated from the peripheral ring to extract and isolate the signal pathways from the grounding structure. This extraction prevents electromagnetic interference between signal and ground paths, ensuring complete shielding effectiveness. The cutting process is integrated into the manufacturing flow, allowing for automated processing despite the additional step.
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 provides significantly improved EM shielding performance, ensuring complete protection for high-frequency and high-speed applications, including health-related sensitive products.
Implementation Method 1
controlled metal plating or other shielding is applied over the module, into contact with the exposed peripheral ring
Implementation Method 2
these materials absorb or reflect unwanted EM energy, preventing the energy from reaching the sensitive parts of the device
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2C
AI summary
Structures and methods for full-enclosure electromagnetic shielding of leadless semiconductor packages provide complete module-level electromagnetic shielding by combining plated shielding with proposed modified leadframe peripheral structure and ground pad grounding. A first cut into an overmolded leadless module exposes the peripheral ring of the leadframe; then, with controlled metal plating a full shielding enclosure is formed over the top of the package into contact with the exposed peripheral ring. The proposed approach provides complete electromagnetic shielding for the module with significantly improved electromagnetic shielding performance. The full enclosure shielding solution is especially important for high frequency and high-speed application and sensing products with high sensitivity to electromagnetic interference.