Directional Coupler Thermal Management via Backside Sensor Line
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Solution Overview
Problem
In plasma processing systems, directional couplers face challenges in maintaining geometric stability and a stable electromagnetic field to achieve accurate RF power measurements, especially due to high power levels and the need for reliable thermal interfacing with an external heat sink.
Innovation Solution
A directional coupler system comprising a substrate with parallel power line traces on the top surface and a sensor line on the backside surface, coupled to a thermo-conductive base platform, which allows for accurate power level determination by inducing a signal in the sensor line proportional to the power signal, while maintaining thermal stability through a thermal interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power levels are passed through the directional coupler to enable plasma processing, then the power handling capability is improved, but thermal stability deteriorates due to heat generation
Solution Approach 1:
The patent extracts the thermal management function by providing a dedicated thermal interface structure that couples the directional coupler to an external heat sink. This separates the power handling function (in the coupler) from the thermal dissipation function (in the heat sink), allowing high power operation while maintaining thermal stability through the extracted thermal path.
Solution Approach 2:
The directional coupler structure is designed to serve multiple functions simultaneously: it handles high power RF signals, provides accurate power measurements through its sensor lines, and interfaces thermally with external heat sinks. The parallel power line traces and sensor lines are integrated into a single structure that performs both power transmission and measurement functions while managing thermal loads.
2Measurement precision
If geometric stability is maintained to ensure accurate RF power measurements, then measurement precision is improved, but device complexity increases due to the need for stable surrounding electromagnetic field
Solution Approach 1:
The patent moves the sensor line to the backside surface of the substrate, creating a spatial separation between the power transmission path (top surface) and the sensing path (backside surface). This dimensional arrangement reduces electromagnetic interference between power lines and sensor lines, simplifying the electromagnetic field environment while maintaining measurement accuracy through the coupled signal induction.
Solution Approach 2:
The substrate acts as an intermediary structure that couples the power lines and sensor lines while providing geometric stability. The substrate's rigid structure maintains precise geometric relationships between traces, ensuring accurate measurements without requiring complex external electromagnetic field control mechanisms.
3Loss of energy
If parallel power line traces are used to draw power from input to output, then power transmission efficiency is improved, but electromagnetic interference increases between the parallel traces
Solution Approach 1:
By placing sensor lines on the backside surface while power lines remain on the top surface, the patent creates spatial separation that reduces electromagnetic coupling between power transmission elements and sensing elements. This dimensional arrangement allows efficient power transmission through parallel traces while minimizing harmful electromagnetic interference through physical separation in the third dimension.
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
This design enhances geometric stability and thermal interfacing, enabling accurate RF power measurements with minimal adjustments required even with displacement offsets, and maintains stable power readings across varying thermal conditions.
Implementation Method 1
A signal is then induced in a sensor line coupled to a substrate backside surface
Implementation Method 2
the need for reliable thermal interfacing with an external heat sink
Data Source
AI summary
One embodiment comprises a directional coupler system comprising a substrate having a top surface and a backside surface, with the backside surface comprising a metalization ground portion and an unmetalized portion. A power line is coupled to the top surface, with the power line having an input adapted to receive a power signal, a first trace coupled to the input, a second trace in parallel with the first trace and coupled to the input, and an output coupled to the first and second traces and adapted to emit the power signal. A sensor line is coupled to the backside surface unmetalized portion, with the sensor line adapted to emit a sensor line signal having a sensor line signal level generally proportional to the power signal. Finally, a thermo-conductive base platform coupled to the metalized portion of the backside surface.