QFN Package Shielding Structure to Prevent Lead Short Circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional QFN packaging structures face issues with electromagnetic interference (EMI) due to direct contact between conductive electromagnetic shielding layers and leads, leading to short circuits and performance degradation.
Innovation Solution
A QFN packaging structure with an insulating layer between leads and an electromagnetic shielding layer, where the shielding layer is grounded via a grounding lead, preventing short circuits and enhancing electromagnetic shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conductive electromagnetic shielding layer directly covers the plastic package, then electromagnetic shielding effectiveness is improved, but short circuit between leads occurs
Solution Approach 1:
An insulating layer is introduced as an intermediary between the conductive electromagnetic shielding layer and the leads. This insulating layer prevents direct electrical contact and potential short circuits while allowing the shielding layer to maintain its electromagnetic shielding function. The insulating layer acts as a mediator that resolves the contradiction between needing conductive shielding and avoiding short circuits.
Solution Approach 2:
The shielding structure is segmented into distinct functional layers: an electromagnetic shielding layer for EMI protection and an insulating layer for electrical isolation. This segmentation allows each layer to perform its specific function independently - the shielding layer provides electromagnetic protection while the insulating layer prevents short circuits, thus resolving the technical contradiction.
2Ease of operation
If leads are exposed on four side surfaces of the plastic package for conventional QFN packaging, then electrical connectivity is improved, but electromagnetic interference to other chips increases
Solution Approach 1:
The insulating layer serves as a mediator that allows the leads to remain exposed for electrical connectivity while preventing them from acting as antennas for electromagnetic interference. The insulating material surrounding the leads isolates their electromagnetic fields, enabling both good electrical connection and reduced EMI radiation.
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
Prevents short circuits and effectively shields against electromagnetic interference while maintaining electrical connectivity, ensuring reliable performance of the QFN packaging structure.
Implementation Method 1
an electromagnetic shielding layer generally directly covers over the plastic package
Implementation Method 2
a high-frequency chip may generate strong electromagnetic waves during the operating process, which may thereby cause interference or noise to other chips in the package
Implementation Method 3
the electromagnetic shielding layer is grounded via the grounding lead
Data Source
AI summary
The present invention provides a QFN packaging structure and QFN packaging method. By providing the insulating layer on the outer side of the leads of the QFN packaging structure, a short circuit between the leads and the electromagnetic shielding layer can be prevented. In addition, the grounding lead is exposed from the insulating layer, such that the electromagnetic shielding layer is grounded via the grounding lead, thereby realizing the electromagnetic shielding design of the QFN packaging structure.