Sapphire / Quartz / Borosilicate CF Vacuum Viewport | UHV High Precision Vacuum Window
Nanjing Kovar Precision: Professional industrial vacuum viewport manufacturer specializing in high-end sapphire vacuum window, quartz vacuum viewport and borosilicate sight glass. Full CF flange sizes CF10~CF400, ultra-low helium leak rate, high pressure & temperature resistance, custom solutions for global semiconductor, aerospace & lab UHV vacuum systems.
Three Series CF Vacuum Viewport
Nanjing Kovar Precision provide three mainstream vacuum window materials to cover low, medium, ultra-high vacuum and extreme working conditions, all standard CF flange sizes CF10 to CF400 in stock
Ultra-high-temperature Sapphire Vacuum Viewport
Top-grade extreme condition vacuum window, highest performance series for ultra high temperature & cryogenic UHV equipment.
- Ultra-high pressure & impact resistance
- Working temp: -196℃ ~ 1200℃, max baking 610℃
- Excellent full UV & infrared transmittance ≥99%
- Mohs 9 hardness, scratch & corrosion resistant
- Leak rate: 1×10⁻⁹ Pa, max positive pressure 0.05MPa
Application: Aerospace space simulation, high temp laser, ultra-high vacuum semiconductor, cryogenic vacuum test
High-pressure Quartz Vacuum Viewport
High-performance universal UHV vacuum window, mainstream choice for laboratory & industrial optical vacuum equipment.
- Visible light transmittance ≥98%, good UV penetration
- Continuous working temperature up to 250℃
- Strong pressure resistance, max positive pressure 0.2MPa
- Vacuum degree up to 1×10⁻⁸ Pa
- Low thermal expansion, stable optical performance
Application: Lab vacuum chamber, semiconductor etching & deposition, optical laser vacuum equipment, vacuum coating
High-temperature Borosilicate Vacuum Glass Viewport
Economical industrial vacuum window, cost-effective for medium vacuum general industrial equipment.
- Cost competitive, mass production short lead time
- Max baking temperature up to 550℃
- Vacuum leak rate 1×10⁻⁹ Pa, positive pressure 0.05MPa
- Stable performance under medium high temperature
- Complete CF flange size from CF16 to CF400
Application: Ordinary industrial vacuum chamber, PVD/CVD coating machine, new energy vacuum production equipment
About us
Professional Vacuum Viewport & Vacuum Component Manufacturer in China
Nanjing Kovar Precision Technology Co., Ltd.
Nanjing Kovar Precision specializes in high-precision vacuum optical components, mainly CF flange vacuum viewports, kovar alloy sealing parts, vacuum flanges and optical windows. We integrate R&D, production and export service, serving vacuum equipment manufacturers, university labs, semiconductor factories and aerospace research institutions all over the world.
- Our factory owns complete CNC machining workshop, high-precision optical polishing production line and helium mass spectrometer leak detection lab. All sapphire, quartz and borosilicate vacuum viewports are strictly inspected before shipment to meet international ultra-high vacuum standards. We support drawings customization, small batch sample order and mass export orders with complete test certificates.
Professional Manufacturing Advantages
Strict production standards and precision CNC processing ensure every CF vacuum viewport meets international UHV industrial standards
Ultra-Low Helium Leak Rate
Precision flat grinding + integral metal compression sealing, all finished CF viewports pass helium mass spectrometer full inspection. Leakage reaches 1×10⁻⁹~1×10⁻⁸ Pa, fully compliant with UHV ultra-high vacuum system requirements.
Wide Temperature Adaptability
Sapphire series supports cryogenic -196℃ and high temp baking up to 610℃. Quartz withstands 250℃ continuous work, borosilicate up to 550℃. No fogging, crack or air leakage under thermal cycling.
High Optical Transmittance
High purity raw material + double-sided precision polishing. Optional anti-reflection coating for laser systems. Sapphire full-spectrum transmittance over 99%, quartz ≥98%, borosilicate ≥92% visible light.
Full Standard CF Flange Series
Complete CF flange stock: CF10, CF16, CF20, CF25m, CF25, CF25b, CF32, CF35, CF40, CF50, CF63, CF75, CF80, CF100, CF125, CF150, CF160, CF200, CF250, CF275, CF300, CF350, CF400. All flanges 304 stainless steel.
Full Customization Support
Custom window diameter, thickness, rectangular/oval special shape, AR coating, non-standard flange. Provide drawing design, sample production and OEM/ODM one-stop service according to client technical drawings.
Strict Multi-Stage Quality Inspection
100% inspection before delivery: dimensional tolerance test, surface optical inspection, helium leak test, pressure resistance test. Formal test reports available for bulk export orders.
Complete CF Vacuum Viewport Technical Specifications
All dimension data strictly follow our factory drawing standard, 304 stainless steel flange as standard material
1. Ultra-high-temperature Sapphire CF Vacuum Viewports
| Ultra-high-temperature sapphire vacuum Viewports | A/mm | B/mm | D/mm | H/mm | n-φd/mm | Material | Temperature | Vacuum Degree | Positive Pressure |
|---|---|---|---|---|---|---|---|---|---|
| CF16 | 34 (1.33") | 27 | 14 | 8 | 6-φ4.3 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF20 | 54 (2.12") | 41.3 | 14 | 10.5 | 6-φ6 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF25m | 54 (2.12") | 41.3 | 22 | 11.5 | 4-φ6.8 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF25 | 54 (2.12") | 43 | 22 | 11 | 6-φ6 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF25b | 60 (2.36") | 47 | 22 | 10.5 | 6-φ6.6 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF32 | 70 (2.75") | 54 | 22 | 12 | 6-φ6.6 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF35 | 70 (2.75") | 58.7 | 34 | 16.5 | 6-φ6 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF40 | 70 (2.75") | 58.7 | 34 | 13 | 6-φ6.6 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF50 | 86 (3.38") | 72.4 | 47 | 18 | 8-φ8 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF63 | 114 (4.50") | 92.2 | 64 | 20 | 8-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF75 | 117.4 (4.62") | 102.3 | 64 | 17.5 | 10-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF80 | 130 (5.12") | 110 | 82 | 20 | 16-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF100 | 152 (6.00") | 130.3 | 104 | 20 | 16-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF125 | 171.5 (6.75") | 151.6 | 104 | 21 | 18-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF150 | 202 (8.00") | 181 | 155 | 22 | 20-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF160 | 203.2 (8.00") | 181 | 155 | 21 | 20-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF200 | 253 (10.00") | 231.8 | 190 | 27 | 24-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF250 | 305 (12.00") | 284 | 155 | 26 | 32-φ8.4 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF275 | 336.6 (13.25") | 306.3 | 155 | 28 | 30-φ10.8 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF300 | 368.3 (14.50") | 338.1 | 155 | 28 | 32-φ10.8 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF350 | 419.1 (16.50") | 388.9 | 155 | 28 | 36-φ10.8 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF400 | 469.9 (18.50") | 437.9 | 155 | 28 | 40-φ10.8 | 304 | 610℃ ↓ | 1*10E-9pa | 0.05mpa |
2. High-pressure Quartz CF Vacuum Viewports
| High-pressure quartz vacuum Viewports | A/mm | B/mm | D/mm | H/mm | n-φd/mm | Material | Temperature | Vacuum Degree | Positive Pressure |
|---|---|---|---|---|---|---|---|---|---|
| CF10 | 25 (1.0") | 17.5 | 10 | 6 | 6-φ3.3 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF16 | 34 (1.33") | 27 | 16 | 7.3 | 6-φ4.3 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF20 | 54 (2.12") | 41.3 | 20 | 10.5 | 6-φ6 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF25m | 54 (2.12") | 41.3 | 25 | 11.5 | 4-φ6.8 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF25 | 54 (2.12") | 43 | 25 | 10.5 | 6-φ6 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF25b | 60 (2.36") | 47 | 25 | 10.5 | 6-φ6.6 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF32 | 70 (2.75") | 54 | 32 | 12 | 6-φ6.6 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF35 | 70 (2.75") | 58.7 | 35 | 13 | 6-φ6 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF40 | 70 (2.75") | 58.7 | 40 | 13 | 6-φ6.6 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF50 | 86 (3.38") | 72.4 | 50 | 16 | 8-φ8 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF63 | 114 (4.50") | 92.2 | 63 | 17.5 | 8-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF75 | 117.4 (4.62") | 102.3 | 75 | 17.5 | 10-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF80 | 130 (5.12") | 110 | 80 | 18 | 16-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF100 | 152 (6.00") | 130.3 | 100 | 20 | 16-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF125 | 171.5 (6.75") | 151.6 | 125 | 21 | 18-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF150 | 202 (8.00") | 181 | 150 | 22 | 20-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF160 | 203.2 (8.00") | 181 | 160 | 21 | 20-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF200 | 253 (10.00") | 231.8 | 200 | 24.5 | 24-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF250 | 305 (12.00") | 284 | 250 | 26 | 32-φ8.4 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF275 | 336.6 (13.25") | 306.3 | 275 | 28 | 30-φ10.8 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF300 | 368.3 (14.50") | 338.1 | 300 | 28 | 32-φ10.8 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF350 | 419.1 (16.50") | 388.9 | 350 | 28 | 36-φ10.8 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
| CF400 | 469.9 (18.50") | 437.9 | 400 | 28 | 40-φ10.8 | 304 | 250℃ ↓ | 1*10E-8pa | 0.2mpa |
3. High-temperature Borosilicate CF Vacuum Glass Viewports
| High-temperature vacuum glass Viewports | A/mm | B/mm | D/mm | H/mm | n-φd/mm | Material | Temperature | Vacuum Degree | Positive Pressure |
|---|---|---|---|---|---|---|---|---|---|
| CF16 | 34 (1.33") | 27 | 14 | 8 | 6-φ4.3 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF20 | 54 (2.12") | 41.3 | 14 | 10.5 | 6-φ6 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF25m | 54 (2.12") | 41.3 | 22 | 11.5 | 4-φ6.8 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF25 | 54 (2.12") | 43 | 22 | 11 | 6-φ6 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF25b | 60 (2.36") | 47 | 22 | 10.5 | 6-φ6.6 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF32 | 70 (2.75") | 54 | 22 | 12 | 6-φ6.6 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF35 | 70 (2.75") | 58.7 | 34 | 16.5 | 6-φ6 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF40 | 70 (2.75") | 58.7 | 34 | 13 | 6-φ6.6 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF50 | 86 (3.38") | 72.4 | 47 | 18 | 8-φ8 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF63 | 114 (4.50") | 92.2 | 64 | 20 | 8-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF75 | 117.4 (4.62") | 102.3 | 64 | 17.5 | 10-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF80 | 130 (5.12") | 110 | 82 | 20 | 16-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF100 | 152 (6.00") | 130.3 | 104 | 20 | 16-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF125 | 171.5 (6.75") | 151.6 | 104 | 21 | 18-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF150 | 202 (8.00") | 181 | 155 | 22 | 20-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF160 | 203.2 (8.00") | 181 | 155 | 21 | 20-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF200 | 253 (10.00") | 231.8 | 190 | 27 | 24-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF250 | 305 (12.00") | 284 | 155 | 26 | 32-φ8.4 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF275 | 336.6 (13.25") | 306.3 | 155 | 28 | 30-φ10.8 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF300 | 368.3 (14.50") | 338.1 | 155 | 28 | 32-φ10.8 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF350 | 419.1 (16.50") | 388.9 | 155 | 28 | 36-φ10.8 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
| CF400 | 469.9 (18.50") | 437.9 | 155 | 28 | 40-φ10.8 | 304 | 550℃ ↓ | 1*10E-9pa | 0.05mpa |
Sapphire / Quartz / Borosilicate Material Performance Comparison
Professional comparison chart to help engineers select the correct vacuum viewport material for your vacuum system
| Performance Parameter | Sapphire CF Viewport | Quartz CF Viewport | Borosilicate CF Viewport |
|---|---|---|---|
| Continuous Working Temperature | -196℃ ~ 610℃, short term 1200℃ | -70℃ ~ 250℃, max 900℃ short baking | -40℃ ~ 550℃ |
| Max Positive Pressure Resistance | 0.05MPa | 0.2MPa | 0.05MPa |
| Ultimate Vacuum Degree | 1×10⁻⁹ Pa UHV | 1×10⁻⁸ Pa HV | 1×10⁻⁹ Pa UHV |
| Visible Light Transmittance | ≥99% Full spectrum UV-IR | ≥98% Visible + UV band | ≥92% Visible light only |
| Hardness & Wear Resistance | Mohs 9, excellent scratch resistant | Mohs 7, good anti-scratch | Mohs 6, general wear performance |
| Chemical Corrosion Resistance | Super strong, acid & alkali resistant | Strong chemical stability | Medium resistance to weak acid |
| Best Application Scenarios | Aerospace simulation, cryogenic vacuum, high power laser, ultra high temp UHV chamber | Semiconductor etching/deposition, optical lab vacuum, medium pressure vacuum coating | General industrial vacuum equipment, cost-sensitive mass production coating machine |
| Product Cost Grade | High-end premium | Mid-high grade | Economical standard grade |
Global Application Fields of CF Vacuum Viewport
Our three series CF vacuum windows are widely supplied to vacuum equipment manufacturers, research institutes and semiconductor factories worldwide
Aerospace Space Simulation
High & low temperature vacuum environmental test tank
Semiconductor Wafer Fabrication
Etching, PVD, CVD, thin film deposition vacuum chamber
Laser & Optical Vacuum Systems
Laser transmission, optical measurement vacuum equipment
University & Lab Research
Material science, surface physics vacuum experiment devices
PVD/CVD Vacuum Coating Line
Decorative coating, optical coating, hard film coating machine
Lithium Battery New Energy
Battery vacuum encapsulation, electrode coating equipment
Cryogenic Low-Temp Vacuum
Cryostat, liquid nitrogen low temperature vacuum test device
Industrial High-Temp Vacuum Furnace
High temperature sintering, annealing vacuum furnace sight window
Technical FAQ For CF Vacuum Viewport Buyers
Answers for engineers, procurement and equipment manufacturers about material selection, flange size, vacuum grade and customization
1. How to choose between sapphire, quartz and borosilicate CF vacuum viewport?
If your system requires long term high temperature baking more than 550℃, cryogenic environment or laser optical transmission, sapphire CF viewport should be chosen. For the medium pressure resistance and UV light transmission for semiconductor lab equipment, quartz CF window is the right choice. Borosilicate CF sight glass is the best cost choice for common low-medium vacuum coating machines with budget control.
2. What is the difference between CF metal seal and KF rubber seal vacuum window?
All our listed viewports use CF knife-edge copper metal sealing. It can reach ultra-high vacuum 1*10-9 Pa, suitable for long time high temperature baking without air leakage. KF rubber sealing is only suitable for medium vacuum above 10^(-3) Pa and cannot bear high temperature baking.
3. Can you supply non-standard custom CF vacuum viewport sizes?
Yes. Besides standard CF10~CF400 sizes in the spec table, we can customize special diameter, rectangular/oval window, thicker optical substrate, anti-reflection coating, modified flange hole layout according to client drawings or technical parameters.
4. Why sapphire vacuum viewport has higher temperature resistance than quartz?
Sapphire single crystal material has extremely stable crystal structure, softening temperature over 2000℃, continuous baking up to 610℃ without deformation. Quartz glass softens around 1700℃ but long-term continuous working limited to 250℃ to avoid creep deformation under vacuum pressure difference.
5. Do you provide helium leak test report for CF vacuum viewports?
Every finished CF vacuum viewport passes helium mass spectrometer full inspection before delivery. For bulk export orders, we can provide formal factory inspection report including leak rate, dimension tolerance and appearance optical test data.
