Interdigitated RF Filter on Glass-Ceramic for Low Insertion Loss
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Solution Overview
Problem
Existing RF devices face challenges in achieving compact, low-loss impedance matching due to mechanical and dimensional instability, leading to high insertion losses and limited use in commercial markets.
Innovation Solution
A method involving a photosensitive glass substrate is used to create a mechanically stabilized RF coupled interdigitated resonate device, where the substrate is masked, exposed to an activating energy source, heated above its glass transition temperature, and etched to form a glass-crystalline substrate with metal coatings, resulting in a compact, low-loss RF filter with reduced mechanical and thermal stabilization structure contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional RF devices are used for impedance matching, then the device structure is simple, but mechanical and dimensional instability leads to high insertion losses
Solution Approach 1:
The patent employs a composite substrate structure combining glass-ceramic material with metal layers (copper, aluminum, or silver) to create a mechanically stable RF device. The glass-ceramic substrate provides dimensional stability and mechanical strength, while the metal layers provide electrical conductivity for RF signal transmission, thereby reducing insertion losses while maintaining structural integrity
Solution Approach 2:
The patent modifies physical parameters of the substrate by controlling the glass transition temperature range (Tg-50°C to Tg+50°C) and adjusting the composition of the glass-ceramic material to achieve optimal mechanical stability. The etching process also changes the physical structure by creating air gaps and removing excess material to improve dimensional stability and reduce parasitic effects
2Stability of the object's composition
If the stabilization structure contact area is increased, then mechanical stability is improved, but RF loss increases due to greater interaction between stabilization structure and RF fields
Solution Approach 1:
The patent applies local quality by providing mechanical stabilization only where absolutely necessary - through minimal contact points or small-area stabilization structures rather than extensive coverage. The stabilization structure is strategically positioned to provide mechanical support while minimizing its footprint to reduce interaction with RF fields and associated losses
3Manufacturing precision
If photosensitive glass substrate processing is used, then manufacturing precision is improved, but device complexity increases due to multiple processing steps
Solution Approach 1:
The patent combines multiple functions into integrated processing steps: the glass-ceramic substrate fabrication integrates photo-patterning, crystallization, and etching in a unified process flow. The metal layers are deposited and patterned in combination with the substrate processing, and the stabilization structures are formed simultaneously with the RF signal paths, thereby achieving high precision while managing complexity through integration
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 approach enables the production of compact, low-loss RF filters with insertion losses less than 10 dB, suitable for commercial applications, by utilizing a glass-ceramic substrate and metal coatings to achieve mechanical and thermal stability while minimizing the stabilization structure's contact area.
Implementation Method 1
heating the photosensitive glass substrate for at least ten minutes above its glass transition temperature
Implementation Method 2
cooling the photosensitive glass substrate to transform at least part of the exposed glass to a crystalline material
Data Source
AI summary
The present invention includes a method of creating electrical air gap low loss low cost RF mechanically and thermally stabilized interdigitated resonate filter in photo definable glass ceramic substrate. Where a ground plane may be used to adjacent to or below the RF filter in order to prevent parasitic electronic signals, RF signals, differential voltage build up and floating grounds from disrupting and degrading the performance of isolated electronic devices by the fabrication of electrical isolation and ground plane structures on a photo-definable glass substrate.