Liquid Crystal Polymer X-Ray Window Mounting for Hermetic Low-Leak Seals
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Solution Overview
Problem
X-ray windows face challenges with hermetic seals that allow light penetration, interfere with signals, are not suitable for high temperatures, and have high outgassing and leakage issues, which can lead to device malfunction.
Innovation Solution
A hermetic seal using a liquid crystal polymer adhesive layer sandwiched between the x-ray window thin film and housing, providing opacity, high temperature resistance, low outgassing, and low leak rates, while accommodating various materials and relieving thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the hermetic seal is made opaque to block light penetration, then light interference with x-ray signals is reduced, but the material selection becomes more restricted and bonding capability may be compromised
Solution Approach 1:
The hermetic seal uses a composite structure combining a polymer adhesive layer with opaque pigments or fillers (such as metal oxides or carbon-based materials). This composite approach allows the seal to block light while maintaining bonding capability to various materials including thin films and housing components.
2Object-affected harmful factors
If low atomic number elements are used in the hermetic seal to reduce x-ray fluorescence interference, then signal quality improves, but the mechanical strength and temperature resistance may be reduced
Solution Approach 1:
The hermetic seal employs local quality by using low atomic number elements (such as carbon, hydrogen, oxygen, nitrogen) in the polymer matrix to minimize x-ray fluorescence, while incorporating high strength additives or fillers (such as glass fibers, aramid fibers, or ceramic particles) in specific regions or concentrations to maintain mechanical strength without significantly increasing atomic number.
3Productivity
If the hermetic seal can withstand high temperatures for quick getter activation, then vacuum pump-down time is reduced, but thermal stress and potential degradation of the seal material increase
Solution Approach 1:
The hermetic seal uses parameter changes by selecting polymer materials with high glass transition temperatures (Tg) and thermal stability (such as polyimides, polyetheretherketone, or other high-performance polymers). These materials can withstand elevated temperatures (above 200°C) required for getter activation without degrading, while their thermal expansion coefficients are matched to adjacent components to minimize thermal stress.
4Reliability
If the hermetic seal has low outgassing to maintain vacuum integrity, then vacuum stability improves, but the material options and bonding versatility are limited
Solution Approach 1:
The hermetic seal acts as an intermediary layer with low outgassing properties (using materials like polyimide or other vacuum-compatible polymers) that bonds to both the thin film and housing. This intermediary seal material is specifically selected to have compatible surface chemistry for bonding to diverse materials while maintaining low vapor pressure and minimal outgassing in vacuum conditions.
5Reliability
If the hermetic seal relieves thermal stress from coefficient of thermal expansion mismatch, then device reliability improves, but the seal structure becomes more complex
Solution Approach 1:
The hermetic seal utilizes thermal expansion principles by selecting polymer materials with coefficients of thermal expansion (CTE) that fall between those of the thin film and housing materials. This intermediate CTE allows the seal to flex and accommodate differential thermal expansion during temperature cycling, relieving stress at the bonding interfaces without requiring complex compensation structures.
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 effectively reduces signal interference, maintains vacuum integrity, and ensures reliable operation of x-ray devices by providing a strong, versatile, and stress-relieving seal with low leakage and high temperature stability.
Implementation Method 1
light penetration through the hermetic seal into an interior of an x-ray detection device can result in interference with a signal from a sample
Implementation Method 2
an adhesive layer sandwiched between and providing a hermetic seal between the thin film and the housing
Data Source
AI summary
An x-ray window can include an adhesive layer sandwiched between and providing a hermetic seal between a thin film and a housing. The adhesive layer can include liquid crystal polymer. The liquid crystal polymer can be opaque, gas-tight, made of low atomic number elements, able to withstand high temperature, low outgassing, low leakage, able to relieve stress in the x-ray window thin film, capable of bonding to many different materials, or combinations thereof.