Guard Ring RF Radiation Suppression in Multilayer Semiconductor Packages
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Solution Overview
Problem
In semiconductor devices with multilayer boards, the electromagnetic coupling between power source and GND planes leads to unnecessary RF radiation, which is difficult to prevent without increasing manufacturing costs, as existing methods require modifying or replacing manufacturing apparatuses.
Innovation Solution
A semiconductor device design featuring a guard ring in the same conductor layer as the power source plane, connected to a GND plane through a via, with a clearance smaller than the insulator thickness, to suppress RF radiation by creating a potential difference that terminates electromagnetic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a closed area conductor is used to wrap the power source plane to prevent RF radiation, then RF radiation leakage is reduced, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The closed area conductor is divided into multiple segments distributed across different layers. Instead of requiring a single continuous conductor wrapping the power source plane, the patent uses multiple conductor segments on different layers that collectively form the closed area, making the structure manufacturable with existing equipment.
Solution Approach 2:
The closed area conductor is implemented across multiple layers in the vertical dimension rather than as a single planar structure. This dimensional approach allows the closed area to be formed using standard multilayer PCB manufacturing processes, avoiding the need for complex 3D conductor structures.
2Object-affected harmful factors
If a closed area conductor is used to wrap the power source plane to prevent RF radiation, then RF radiation leakage is reduced, but manufacturing cost increases
Solution Approach 1:
The closed area conductor is segmented across multiple layers, allowing each segment to be manufactured using standard PCB processes. This eliminates the need for expensive custom manufacturing equipment while achieving the same EMI shielding effect.
Solution Approach 2:
The conductor segments serve dual purposes: they provide electrical connectivity for power or signal distribution and simultaneously form the closed area structure for EMI shielding. This multi-functionality eliminates the need for separate shielding structures, reducing manufacturing cost.
3Reliability
If the power source plane and GND plane are opposed in the same area, then electromagnetic coupling occurs, but this causes needless RF radiation to be generated
Solution Approach 1:
An insulator layer is introduced between the power source plane and GND plane to mediate their electromagnetic interaction. This insulator controls the coupling between the planes, maintaining necessary electrical relationships while reducing parasitic effects that lead to RF radiation.
Solution Approach 2:
A thin insulator film is used between the conductive planes to provide electrical isolation while maintaining close proximity for controlled coupling. This thin film structure allows the planes to remain opposed for connectivity while preventing excessive electromagnetic coupling that would generate RF 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
Effectively prevents RF radiation from leaking outside the package without significantly increasing manufacturing costs, as the guard ring and vias can be easily manufactured using common semiconductor device manufacturing equipment.
Implementation Method 1
a via connecting the first conductive plane and the guard ring through the insulator
Implementation Method 2
the electromagnetic coupling between power source and GND planes leads to unnecessary RF radiation
Data Source
AI summary
In a lamination type semiconductor device, in the case where a power source plane is wrapped by a closed area to prevent the needless radiation from being leaked to the outside of the semiconductor package, a planar conductor for shield having an area intersecting with the respective layers is required. However, in a device for manufacturing the lamination type semiconductor device, a process for manufacturing the above-mentioned conductor cannot be realized ordinarily. In order to make the process possible, it is required to modify or replace a manufacturing apparatus of the semiconductor device, and accordingly a manufacturing cost will be considerably increased. In the present invention, a guard ring is arranged in an surrounding area of a power source plane. The guard ring is connected to a GND plane of another layer through a via. Consequently, the RF radiation occurs between the power source plane and the guard ring.