Air-Core Transformer Package With Ferrite Shielding for IC Chip EMI
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Solution Overview
Problem
The integration of a transformer with a semiconductor chip in a package is hindered by Electro-Magnetic Interference (EMI) generated by the transformer coil, which can damage the chip and prevent effective signal transmission.
Innovation Solution
A semiconductor package design that incorporates a ferrite-dielectric shield to shield the semiconductor chip from the EMI generated by the transformer coil, while also increasing the inductance of the transformer by using a ferrite layer sandwiched between dielectric laminate layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the transformer coil is placed near the semiconductor chip to achieve integration, then the package size is reduced, but the electromagnetic field from the coil induces unwanted currents in the chip that can damage it
Solution Approach 1:
A ferrite-dielectric shield is introduced as an intermediary component between the transformer coil and the semiconductor chip. The ferrite layer absorbs and redirects electromagnetic fields, while the dielectric laminate provides electrical isolation. This mediator allows the coil and chip to be in close proximity for integration while preventing direct harmful electromagnetic coupling that would damage the chip.
Solution Approach 2:
The shielding structure is segmented into multiple functional layers: a ferrite layer for magnetic field management and dielectric laminate layers for electrical isolation. This segmentation allows each layer to perform its specific function optimally - the ferrite handles electromagnetic interference while the dielectric layers provide electrical separation - enabling close integration without direct harmful interaction.
2Object-affected harmful factors
If the package size is increased to space the chip and transformer apart, then electromagnetic interference is reduced, but the package becomes many times larger than desirable for area and cost-constrained applications
Solution Approach 1:
The ferrite-dielectric shield acts as a localized intermediary that provides EMI protection without requiring large spacing. The ferrite material's magnetic properties allow it to absorb and redirect electromagnetic energy, while the dielectric layers provide electrical isolation. This enables the coil and chip to remain in close proximity (maintaining small package size) while the shield prevents harmful electromagnetic coupling.
Solution Approach 2:
The invention changes the electromagnetic parameters of the space between coil and chip by introducing ferrite material with specific magnetic permeability and dielectric layers with specific electrical properties. These parameter changes allow the electromagnetic field to be managed locally, providing protection without requiring increased physical distance between components.
3Ease of manufacture
If an air-core transformer is used for ease of manufacture, then the transformer can be easily integrated, but the inductance is too low for power converter applications
Solution Approach 1:
The transformer structure uses a composite of air-core simplicity and ferrite-enhanced inductance. The ferrite-dielectric shield layers are positioned to couple with the air-core transformer's magnetic field, providing inductance boosting without requiring complex wound cores. This composite approach maintains the ease of manufacturing planar air-core transformers while achieving the higher inductance values needed for power converter applications through the ferrite material's magnetic properties.
Solution Approach 2:
The invention changes the magnetic parameter (inductance) of the transformer by introducing ferrite material near the air-core coil. The ferrite's high magnetic permeability concentrates and enhances the magnetic flux, significantly increasing the inductance value without changing the basic air-core structure or winding process. This allows the same easy-to-manufacture planar transformer geometry to achieve power-converter-level inductance.
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 shield effectively reduces EMI at the semiconductor chip by approximately 90%, while the ferrite layer increases the transformer's inductance, allowing for a more compact and efficient package that can be used in area and cost-constrained applications.
Implementation Method 1
A semiconductor package design that incorporates a ferrite-dielectric shield to shield the semiconductor chip from the EMI generated by the transformer coil
Implementation Method 2
A semiconductor package design that incorporates a ferrite-dielectric shield to shield the semiconductor chip from the EMI generated by the transformer coil
Implementation Method 3
the ferrite layer increases the transformer's inductance, allowing for a more compact and efficient package
Implementation Method 4
A semiconductor package design that incorporates a ferrite-dielectric shield to shield the semiconductor chip from the EMI generated by the transformer coil, while also increasing the inductance of the transformer by using a ferrite layer
Data Source
AI summary
An Integrated Circuit (IC) package has a ferrite-dielectric shield between planar transformer coils and a semiconductor chip. The shield blocks Electro-Magnetic Interference (EMI) generated by currents in transformer coils from reaching the semiconductor chip. Multiple layers of planar transformer coils serve as primary or secondary coils and can be connected together in series or parallel using center posts and coil extensions from outer coil windings to lead-frame risers that also have external package connectors such as pins or bonding balls. The center winding of an upper transformer coil connects to the semiconductor chip on a die attach pad through a center post that fits through an opening in the shield that is over the air core center of the transformer coil. Bonding wires connect pads on the semiconductor chip to lead-frame pads on lead-frame risers that end at external package connectors.