Leadframe Inductor 3D Stacking for High Density and Low EMI
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Solution Overview
Problem
Conventional inductors face challenges in achieving high inductance density and reducing electromagnetic interference (EMI) while maintaining low direct current resistance (DCR) and high saturation current, especially when integrated into compact semiconductor packages.
Innovation Solution
A leadframe inductor is formed with electrically conductive material and a magnetic core, where the magnetic material is strategically placed between the die and the conductive material to enhance inductance and shield against EMI, allowing for three-dimensional stacking and high current capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional inductor designs are used in compact semiconductor packages, then the inductor can be integrated into the package, but the inductance density is low and EMI is high
Solution Approach 1:
The patent transitions from planar inductor layouts to a three-dimensional configuration by stacking the inductor structure vertically above the die. This vertical arrangement increases inductance density by utilizing the third dimension (height) rather than only horizontal space, while the stacked configuration also provides natural EMI shielding between layers
Solution Approach 2:
The patent employs composite material structures combining magnetic materials with conductive materials in a layered configuration. The magnetic material layers enhance the inductance of the conductive windings, achieving higher inductance density in a compact volume. This composite approach also helps contain magnetic fields and reduce EMI radiation
2Area of stationary object
If inductor size is reduced for compact packaging, then area consumption is reduced, but direct current resistance increases
Solution Approach 1:
The patent compensates for reduced planar area by extending the inductor structure vertically. Multiple turns of conductive material are stacked in the vertical dimension, maintaining sufficient current path length and cross-sectional area to keep DCR low, while the overall footprint remains compact. This 3D configuration allows adequate current flow capacity without requiring large horizontal space
Solution Approach 2:
The patent optimizes the local geometry of the inductor windings by varying the cross-sectional dimensions and winding patterns in different regions. Thicker conductive sections are placed where current density is highest to minimize resistive losses, while maintaining compact overall dimensions. The magnetic material is strategically positioned to enhance inductance in critical areas without increasing overall size
3Area of stationary object
If inductor size is reduced for compact packaging, then area consumption is reduced, but saturation current capability decreases
Solution Approach 1:
The patent achieves high saturation current capability in a compact footprint by utilizing vertical stacking. Multiple parallel conductive paths are arranged in the vertical dimension, providing multiple current flow channels that can handle high total current without requiring large horizontal area. The stacked magnetic material layers also help distribute and manage the magnetic flux density, preventing saturation at lower current levels
Solution Approach 2:
The composite structure of magnetic and conductive materials is optimized for high current applications. The magnetic material cores provide high permeability paths that concentrate magnetic flux efficiently, allowing the inductor to handle higher currents before saturation. The conductive windings are designed with sufficient cross-sectional area and appropriate material selection to carry high currents with minimal resistive heating, all within a compact packaged form factor
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 achieves improved inductance density, reduced EMI, and low DCR, enabling efficient power applications in compact integrated circuit packages with reduced area consumption.
Implementation Method 1
Many inductors have a magnetic core made of iron or ferrite inside the coil, which serves to increase the magnetic field and thus the inductance
Implementation Method 2
When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, according to Faraday's law of electromagnetic induction
Implementation Method 3
According to Lenz's law, the direction of induced electromotive force (EMF) opposes the change in current that created it
Data Source
AI summary
One example includes a device that is comprised of a die, a leadframe, and an electrically conductive material. The die includes a circuit therein. The leadframe is coupled with the die and the circuit therein. The electrically conductive material is disposed in a space above the die opposite the leadframe, the electrically conductive material being coupled to the leadframe and configured as one or more turns thereof to form at least one inductor.