Low-Profile Package Shielding Using Magnetic and Conductive Layers
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Solution Overview
Problem
Integrated switching voltage regulators (VRs) generate significant switching harmonic noise, leading to electromagnetic interference (EMI) and radio frequency interference (RFI) issues, which cause regulatory violations and degrade data throughput, and conventional shielding solutions increase the z-height of semiconductor packages, limiting small form factor designs.
Innovation Solution
A low-profile inductor shield is implemented using a magnetic layer and a conductive layer formed between the inductor and the foundation layer, reducing EMI/RFI noise without increasing the z-height or number of discrete components, and eliminating the need for on-board Faraday cages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an on-board Faraday cage is used to shield the VR inductor, then EMI and RFI noise is suppressed, but the z-height of the package significantly increases
Solution Approach 1:
The shielding function is segmented into multiple thin layers (conductive layer and magnetic layer) distributed across different planes within the foundation layer, replacing the single thick Faraday cage structure. This segmentation allows EMI/RFI suppression while maintaining a low z-height profile.
Solution Approach 2:
The shielding approach transitions from a vertical dimension solution (thick Faraday cage increasing z-height) to a horizontal dimension solution (distributed conductive and magnetic layers within the foundation layer plane). This dimensional shift achieves shielding effectiveness without compromising the low-profile requirement.
2Object-affected harmful factors
If an on-board Faraday cage is used to shield the VR inductor, then EMI and RFI noise is suppressed, but the keep-out-zone distance increases reducing PCB area utilization
Solution Approach 1:
The shielding layers are merged with the foundation layer structure itself, eliminating the need for separate shielding enclosures and large keep-out zones. The conductive and magnetic layers are integrated directly into the foundation layer, maximizing PCB area utilization while maintaining shielding effectiveness.
Solution Approach 2:
Instead of creating a large external enclosure around the inductor (traditional approach), the shielding is inverted by placing thin layers directly beneath and within the foundation layer, effectively shielding the inductor from below and the sides without requiring lateral keep-out zones.
3Object-affected harmful factors
If conventional shielding solutions are used, then EMI and RFI noise is suppressed, but the number of discrete components and manufacturing complexity increase
Solution Approach 1:
The foundation layer serves multiple functions simultaneously: it provides mechanical support, electrical connectivity, and EMI/RFI shielding through the integrated conductive and magnetic layers. This multi-functionality eliminates the need for separate discrete shielding components, reducing overall device complexity.
Solution Approach 2:
The shielding structure uses composite material construction with both conductive material (for EMI shielding) and magnetic material (for RFI shielding and flux guidance) integrated within the foundation layer. This composite approach achieves superior shielding effectiveness while maintaining a unified low-profile structure that simplifies manufacturing compared to assembling multiple discrete components.
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
The solution effectively suppresses VR harmonic noise, reduces EMI/RFI risks, and enables smaller form factor designs by minimizing the keep-out-zone distance and maintaining inductor characteristics, thus reducing manufacturing complexity and regulatory violations.
Implementation Method 1
packaging solutions typically shield the VR inductors with an on-board Faraday cage (or an EMI shield enclosure) in SOC packages to suppress the EMI and RFI of the integrated VRs
Implementation Method 2
A low-profile inductor shield is implemented using a magnetic layer and a conductive layer formed between the inductor and the foundation layer
Data Source
AI summary
Semiconductor packages and a method of forming a semiconductor package are described. The semiconductor package has a foundation layer, a conductive layer formed in the foundation layer, and a magnetic layer formed between the conductive and the foundation layer. The conductive layer and the magnetic layer are coupled to form a low-profile inductor shield. The semiconductor package also has a dielectric layer formed between the magnetic and foundation layer. The foundation layer is mounted between a motherboard and a semiconductor die, where the foundation layer is attached to the motherboard with solder balls. Accordingly, the low-profile inductor shield may include a z-height that is less than a z-height of the solder balls. The low-profile inductor shield may have solder pads that are coupled to the conductive layer. The foundation layer may include at least one of voltage regulator and inductor, where the inductor is located above the low-profile inductor shield.