Ferrite-Dielectric EMI Shield for Hybrid IC-Inductor Packages
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Solution Overview
Problem
The integration of semiconductor chips and inductors in a single package is hindered by electromagnetic interference (EMI) from the inductor coil, which can damage the chip and requires large packages to prevent interference, making it unsuitable for area and cost-constrained applications like IoT devices.
Innovation Solution
A semiconductor package with an air-core inductor coil surrounded by ferrite-dielectric shields, which increases the inductance and shields the chip from EMI by limiting the electromagnetic field to a small region between the ferrite layers, reducing interference and allowing for a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the package size is increased to space the chip and inductor apart, then EMI harm to the semiconductor chip is reduced, but the package becomes many times larger than desirable and takes up too much area on the PCB
Solution Approach 1:
A ferrite-dielectric shield is introduced as an intermediary component between the inductor coil and the semiconductor chip. The ferrite layer absorbs and redirects electromagnetic fields, while the dielectric laminate provides electrical isolation. This mediator structure blocks EMI paths without requiring increased spacing, thus protecting the chip while maintaining a compact package footprint.
Solution Approach 2:
The ferrite-dielectric shield is nested within the existing package structure, positioned between the inductor coil and the chip. This nested configuration allows the EMI shielding function to be integrated into the existing package volume without requiring additional external space, effectively protecting the chip while maintaining compact dimensions.
2Ease of manufacture
If an air-core inductor is used, then the inductor is easier to make and has lower energy loss, but the inductance value is too low for power converter applications
Solution Approach 1:
The inductor structure is enhanced by introducing ferrite material as a composite element surrounding the air-core coil. The ferrite layer increases the magnetic permeability of the structure, thereby boosting the inductance value without requiring a change to the air-core construction or additional winding complexity. This composite approach maintains ease of manufacture while achieving the required inductance for power converter applications.
3Area of stationary object
If the inductor coil is placed near the semiconductor chip, then the package size is reduced, but the electromagnetic field induces unwanted currents in metal traces that can damage the chip
Solution Approach 1:
The ferrite-dielectric shield serves as a protective intermediary positioned between the inductor coil and the semiconductor chip. The ferrite material absorbs electromagnetic energy and redirects it away from the chip, while the dielectric layer provides electrical isolation. This mediator structure enables close spacing for compact packaging while preventing EMI-induced currents that would compromise chip reliability.
Solution Approach 2:
The ferrite material converts the harmful electromagnetic field into a beneficial effect by absorbing and redirecting the energy away from the chip. The electromagnetic energy that would otherwise induce damaging currents is instead captured and dissipated by the ferrite shield, transforming a harmful interaction into a protective mechanism that enables close component spacing.
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 ferrite-dielectric shields effectively reduce EMI by 2000 times, allowing for a compact and cost-effective integration of semiconductor chips and inductors, achieving respectable inductance values comparable to magnetic-core inductors while preventing chip damage.
Implementation Method 1
ferrite-dielectric shields, which increases the inductance and shields the chip from EMI by limiting the electromagnetic field to a small region between the ferrite layers
Implementation Method 2
A semiconductor package with an air-core inductor coil surrounded by ferrite-dielectric shields, which increases the inductance
Data Source
AI summary
An Integrated Circuit (IC) package has a ferrite-dielectric shield between a planar inductor coil and a semiconductor chip. The shield blocks Electro-Magnetic Interference (EMI) generated by currents in the inductor coil from reaching the semiconductor chip. The shield has a ferrite layer surrounded by upper and lower dielectric laminate layers to prevent electrical shorts. The center end of the inductor coil connects to the semiconductor chip through a center post that fits through an opening in the shield that is over the air core center of the inductor coil. The center post can connect to a die attach pad that the semiconductor chip is mounted to. Bonding wires connect pads on the semiconductor chip to lead-frame pads on lead-frame risers that end at external package connectors. The outer end of the inductor coil connects to lead-frame outer risers also having external package connectors such as pins or bonding balls.