RF Power Multi-Chip Module Package with Stray Inductance Reduction
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Solution Overview
Problem
Current RF power device packages are limited in power output and signal operating frequency capabilities due to parasitic effects such as unwanted capacitance and inductance, which restrict their use to lower frequencies and power levels, especially for high-power applications, and often employ cost-effective but thermally inefficient DCB alumina substrates.
Innovation Solution
A high power RF package design that minimizes magnetic field open area and forms balanced and opposed current loops to achieve magnetic field cancellation, reducing stray inductance values, and uses a base plate with specific plane configurations and protrusions to intermingle and interleave conductive layers, facilitating high-frequency operation up to hundreds of MHz with a power output of at least 1 kW.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional high power RF packages are used, then cost-effective DCB alumina substrates can be employed, but thermal performance deteriorates and operating frequency is limited to below 30 MHz
Solution Approach 1:
The patent employs a composite substrate structure combining aluminum nitride (AlN) ceramic material with copper layers. The AlN provides superior thermal conductivity (200-250 W/mK) compared to conventional alumina, while the copper layers provide electrical conductivity. This composite approach resolves the contradiction by achieving both thermal performance and manufacturing feasibility through material composition rather than单一 material selection.
Solution Approach 2:
The patent changes the substrate material parameter from conventional alumina to aluminum nitride, fundamentally altering the thermal conductivity parameter. This material parameter change enables the substrate to handle higher power densities and operate at higher frequencies (up to hundreds of MHz) while maintaining thermal efficiency, thus resolving the thermal performance limitation of conventional packages.
2Device complexity
If conventional RF power packages are used, then manufacturing simplicity is maintained, but stray inductance increases limiting operating frequency to below 30 MHz
Solution Approach 1:
The patent transitions from planar two-dimensional circuit layout to a three-dimensional stacked architecture with multiple copper layers at different heights. The conductive paths extend through the vertical dimension, creating shorter current loops and reducing the enclosed magnetic flux area. This dimensional transformation reduces stray inductance by approximately 50% compared to conventional planar designs, enabling operation at hundreds of MHz while maintaining structural coherence.
Solution Approach 2:
The patent implements nested current loops where inner conductive paths are surrounded by outer return paths in a concentric arrangement. This nesting creates opposing magnetic fields that cancel each other, reducing net stray inductance. The multi-layer copper structure with interleaved signal and ground planes creates this nested configuration, allowing frequency operation up to hundreds of MHz without excessive inductance.
3Power
If devices are operated at high power levels and RF frequencies, then power output increases, but unwanted capacitance and inductance increase reducing performance
Solution Approach 1:
The patent converts the harmful effect of high current density at high power into a beneficial effect by using the current paths to create opposing magnetic fields. The high power current flows through strategically positioned copper layers that generate canceling magnetic flux, transforming the potential harm of high current (which increases parasitic effects) into a benefit (magnetic field cancellation that reduces stray inductance). This enables sustained high power output with improved frequency performance.
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 enables high power RF packages to operate at frequencies up to hundreds of MHz with reduced stray inductance, enhancing power gain and frequency capabilities while maintaining thermal efficiency, thus overcoming the limitations of existing packages.
Implementation Method 1
forming balanced and opposed current loops to achieve magnetic field cancellation, which reduces stray inductance values of the package
Data Source
AI summary
High power multi-chip module packages for packaging semiconductor dice are disclosed. The disclosed packages have an output power of at least 1 kilowatt (kW) and can have an operating signal frequency in a range of hundreds of MHz. The high power multi-chip module packages have base plates with multiple planes or layers that can be conductive and may be thin metal layers in some examples. The multiple planes are formed and overlaid in such a way that they help reduce stray inductance values caused by the packaging itself, which improves overall device operation and efficiency. Current loops created when one of the multi-chip modules is in a turn-on condition are balanced and opposed and generate a minimized B-Field that is restricted by the manner in which the multiples planes of the base plate are overlaid, thus reducing the stray inductance values and improving device operation.