PCB Waveguide Launch With Integrated Backshort Hermetic Sealing
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Solution Overview
Problem
Current waveguide launch systems face challenges in manufacturing cost, alignment tolerances, and environmental protection of sensitive integrated circuit units, particularly at high frequencies, due to the use of mechanical backshorts and open air channels, which affect RF performance and increase costs.
Innovation Solution
A waveguide launch system utilizing a separate waveguide channel with integrated electrically conductive backshorts formed by printed circuit boards, where the backshorts are integrated into the PCB structure, providing hermeticity and wideband RF performance, eliminating the need for labor-intensive mechanical backshorts and maintaining compatibility with thin RF circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical backshorts are used with two-part assembly, then environmental protection of integrated circuit units is achieved, but manufacturing cost increases due to small alignment tolerances at high frequencies
Solution Approach 1:
The patent merges the backshort function with the PCB structure by integrating an electrically conductive layer into the PCB lamina. This eliminates the need for separate mechanical backshort components and their complex two-part assembly, thereby reducing manufacturing cost while maintaining the required alignment tolerances through direct integration into the PCB manufacturing process.
Solution Approach 2:
The patent replaces the mechanical backshort system with an electrically conductive structure integrated into the PCB. Instead of using mechanical components that require precise alignment and assembly, the solution uses a conductive layer patterned on the PCB that provides the same electromagnetic function, substituting mechanical complexity with electrical functionality.
2Reliability
If mechanical backshorts with precise alignment are used, then RF performance is maintained, but device complexity increases due to multiple assembled parts
Solution Approach 1:
The backshort function is merged with the PCB structure itself. The electrically conductive layer is integrated into the PCB lamina, creating a unified structure that eliminates multiple separate parts. This reduces device complexity while maintaining the precise geometric relationships needed for RF performance through direct PCB fabrication processes.
3Device complexity
If open air channel is used from waveguide to integrated circuit unit, then structural simplicity is achieved, but hermeticity is compromised exposing integrated circuit units to humidity
Solution Approach 1:
The patent uses a dielectric lid as a thin film structure that closes the waveguide cavity while allowing RF signals to pass through. This dielectric lid provides hermetic sealing to protect the integrated circuit unit from humidity and environmental contaminants, while maintaining the relatively simple overall structure of the waveguide launch system.
4Reliability
If PCB lamina thickness is reduced to match chip thickness, then bond wire length is minimized improving RF performance, but wideband patch antenna design becomes impossible
Solution Approach 1:
The patent compensates for the thin PCB lamina by utilizing the third dimension (vertical spacing) between the patch antenna elements. By adjusting the spacing and positioning in the vertical dimension, the design achieves wideband performance despite the limited thickness available in the lateral dimensions. This dimensional approach allows wideband operation without requiring excessive bond wire lengths.
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 system achieves cost-effective manufacturing, hermetic protection, and wideband RF performance suitable for mm-wave frequencies, while being compatible with standard low-cost PCB technologies and providing structural robustness.
Implementation Method 1
an electrically conductive backshort cover configured to reflect the radio frequency signal waves
Implementation Method 2
where a waveguide mode is excited and transmit the radio frequency signal waves
Implementation Method 3
the electrically conductive barrier arrangement and the electrically conductive backshort cover form an integrated electrically conductive backshort volume
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~4
AI summary
The present invention concerns a waveguide launch system (1 ) configured for translating radio frequency (RF) signal waves. The system (1 ) comprises a first printed circuit board lamina (5) comprising an electrically conductive ground member (7) and configured for attachment of a separate waveguide element (4), having a first cross-section area (A1 ), thereto. A second printed circuit board lamina (9) comprising an electrically conductive backshort cover (1 1 ) configured to reflect the RF signal waves is bonded to the a first printed circuit board lamina (5). An electrically conductive barrier arrangement (19) extends through the second printed circuit board lamina (9). The electrically conductive barrier arrangement (19) and the electrically conductive backshort cover (1 1 ) form an integrated electrically conductive backshort volume (21 ) of an integrated backshort (22) having a second cross-section area (A2). The second cross-section area (A2) is smaller than the first cross-section area (A1 ).