Vacuum Heater O-Ring Shielding for Annealing
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Solution Overview
Problem
Conventional vacuum heating apparatuses using O ring seals for high-temperature annealing of silicon carbide substrates face deterioration due to radiation heating, leading to reduced vacuum properties and substrate surface roughness.
Innovation Solution
The vacuum heating apparatus incorporates bonding steps on the joint surfaces between the heating means and the O ring, preventing radiation heating from reaching the O ring, thereby maintaining vacuum integrity and allowing stable high-temperature annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an O ring seal is used in the vacuum chamber for high-temperature annealing, then vacuum sealing is achieved, but the O ring deteriorates due to radiation heating from the heater, reducing vacuum properties
Solution Approach 1:
A shielding plate is introduced as an intermediary component between the heater and the O ring seal. This plate blocks thermal radiation from reaching the O ring, preventing its deterioration while allowing the heater to maintain high annealing temperatures. The shielding plate acts as a mediator that protects the vulnerable seal component from the harmful thermal environment.
Solution Approach 2:
The vacuum chamber structure is modified with localized shielding features around the O ring seal area. Instead of uniformly cooling or protecting the entire chamber, the shielding is specifically applied to the region where the O ring is located, providing targeted protection against radiation heating while maintaining high temperature conditions in the annealing zone.
2Temperature
If an O ring seal is used in the vacuum chamber, then vacuum sealing is achieved, but substrate surface flatness deteriorates due to O ring gas release
Solution Approach 1:
The shielding plate serves as a protective intermediary that prevents thermal radiation from degrading the O ring seal. By blocking the radiation path, the shield maintains the O ring's structural integrity and sealing performance, preventing gas leakage that would otherwise contaminate the substrate surface and reduce flatness.
Solution Approach 2:
The shielding plate is installed in advance to prevent O ring deterioration before it occurs. This proactive protection measures prevents the chain reaction of O ring degradation → gas release → substrate contamination → surface roughness, thereby maintaining manufacturing precision throughout the annealing process.
3Productivity
If radiation heating is used for high-temperature annealing, then heating efficiency is improved, but O ring deterioration accelerates
Solution Approach 1:
The shielding plate is positioned to selectively block radiation paths to the O ring while allowing radiation to reach the substrate and heater. This directional shielding maintains high heating efficiency for the workpiece while protecting the seal component, effectively decoupling the heating function from the degradation of the sealing system.
Solution Approach 2:
The radiation field is locally differentiated: the substrate and heater receive full radiation heating for efficient high-temperature processing, while the O ring region is locally shielded to prevent deterioration. This spatially selective approach maintains productivity while extending component service life.
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 solution enables stable high-temperature annealing of silicon carbide substrates with maintained vacuum properties and surface flatness, even after repeated cycles, by shielding the O ring from radiation heating.
Implementation Method 1
an electron impact (collision) heating device in which a thermo-electron emitted from a filament by an acceleration voltage is caused to collide with a heater to generate heat
Implementation Method 2
a thermo-electron emitted from a filament by an acceleration voltage is caused to collide with a heater to generate heat
Implementation Method 3
an amount of thermo-radiation to the vacuum chamber is significantly increased as compared with in an annealing process with thermo-radiation from a heater of about 1000° C.
Data Source
AI summary
Deterioration of an O ring due to radiation heating in a vacuum heating apparatus is prevented to allow heat treatment of a substrate with good annealing properties. The vacuum heating apparatus 1 includes a vacuum chamber 2 constituted by flanges 11 and 12 having an opening portion 9 and joined together, a turbo molecular pump 17 for exhausting gas from the vacuum chamber 2, and a heater base 3 for heating a substrate 5 placed in the vacuum chamber 2. Joint surfaces of the flanges 11 and 12 are sealed by an O ring 10. Further, bonding steps 13 are formed between the heater base 3 and the O ring 10 on the joint surfaces of the flanges 11 and 12, thereby preventing thermo-radiation from the heater base 3 from reaching the O ring 10 through the joint surfaces of the flanges 11 and 12.