EMI Shielding via Exposed Ground Structures
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Solution Overview
Problem
Conventional EMI shielding methods face challenges in ensuring a reliable electrical connection with exposed ground wires in reduced thickness package substrates, leading to ineffective EMI shielding.
Innovation Solution
The implementation of thicker and/or wider electrically conductive ground structures, such as wire bonds, pillars, or solder balls, which are bonded to ground pads and exposed during the molding process, allowing for a more reliable connection with an EMI shield layer on both the top and side surfaces of the molding compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate thickness is reduced to achieve thinner packages, then the package size is reduced, but the reliability of electrical connection between the EMI shielding layer and ground wire deteriorates
Solution Approach 1:
The ground structure is extended vertically from the substrate surface to create a three-dimensional configuration. This vertical extension allows the ground structure to protrude through the molding compound, providing an accessible surface for the EMI shielding layer to contact without requiring thicker substrate, thus resolving the contradiction between thin package size and reliable electrical connection.
2Reliability
If the ground wire exposure is increased to improve EMI shielding connection, then the electrical connection reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The ground structure is formed as a pre-configured three-dimensional feature on the substrate before molding. This preliminary formation of the ground structure with its vertical extension ensures that the exposure and contact surface are already prepared, simplifying subsequent molding and EMI shielding layer application processes, thereby improving reliability without significantly increasing manufacturing complexity.
Data Source
AI summary
Packages and packaging techniques for providing EMI shielding are described. In an embodiment, a package includes an electrically conductive ground structure on a ground pad at a periphery of a package substrate. The electrically conductive ground structure is encapsulated in a molding compound, and a surface of the electrically conductive ground structure is exposed at a side surface of the molding compound. An electrically conductive shield layer is on top and side surfaces of the molding compound, and in physical contact with the surface of the exposed electrically conductive ground structure.