High-Purity Quartz Glass Products for Da Nang Facilities
Direct-from-factory fused silica components manufactured from Donghai crystal raw materials. Every item features tight geometric tolerances, ultra-low trace element contamination, and verified high-temperature resilience.
High Temperature Transparent UV Quartz Glass Plate
Transparent U-Bent Quartz Glass Tube Bending Services
Chemisorption BET High-Pressure Quartz Twin Tube
Custom Medical Grade Quartz Glass Ampoules
Circular Fused Quartz XRD Sample Holder
Customized High-Pressure Clear Quartz Glass Tube
High Precision Fused Silica Quartz Glass Wafer
Factory Custom High-Pressure Pure Quartz Tube
Engineering High-Purity Thermal Barrier Solutions for Da Nang's Tech Sector
As Central Vietnam accelerates its strategic evolution toward advanced electronics, semiconductor packaging, and green technology, the local demand for pristine thermal-processing hardware has reached an unprecedented turning point.
Strategic Supply Chain Assessment: In accordance with the Da Nang Master Plan toward 2030 (Vision 2045), the city is aggressively scaling infrastructure at the Da Nang Hi-Tech Park (DHTP), Lien Chieu Industrial Zone, and Hoa Khanh Industrial Cluster. The influx of international investments in microelectronics assembly, test, and packaging (ATP), advanced photovoltaic cell manufacturing, and high-temperature specialty material syntheses requires an uncompromising standard of consumable hardware. Among these, the fused quartz furnace tube represents the primary thermal containment vessel in which high-budget chemical and metallurgical processes occur.
Purity & Contamination Immunity
Trace alkali metals such as Sodium (Na), Potassium (K), and Lithium (Li), along with transition elements like Iron (Fe) and Copper (Cu), compromise semiconductor junction integrity. Zelvo's natural fused silica tubes guarantee total metallic impurity levels below 15–20 ppm, safeguarding epitaxial wafer lots in cleanroom diffusion operations.
- SiO₂ Purity: ≥ 99.99% (4N Grade)
- OH Content: Standard < 20 ppm / De-hydroxylated < 5 ppm
- Zero Heavy Metal Outgassing
Extreme Thermal Shock Resilience
Thermal fatigue remains the leading cause of tube collapse during rapid ramp-down cycles. With an extraordinarily low linear coefficient of thermal expansion (5.5 × 10⁻⁷ /°C), our tubes sustain instantaneous thermal shocks from 1100°C down to 20°C ambient water quench without micro-crack propagation or structural shearing.
- Continuous Service: 1100°C to 1150°C
- Peak Excursion Point: 1300°C (Short Duration)
- Softening Point Threshold: 1683°C
Geometric Precision & Vacuum Integrity
Modern automated horizontal and vertical furnace sleds demand rigid ovality and camber limits to avert vacuum seal blowouts. Zelvo employs continuous laser gauging during drawing, maintaining outer diameter (OD) and wall thickness concentricity within tight tolerances (±0.15 mm), ensuring hermetic mating with KF, ISO, and ConFlat flange assemblies.
- Diameter Span: OD 3 mm up to OD 450 mm
- Wall Uniformity: Symmetrical concentric draw
- End Fabrication: Flame fire-cut or optical ground
Fused Quartz Material Characteristics & International Standards
Before sourcing process equipment for Da Nang cleanrooms or university research labs, process engineers must verify key mechanical, thermal, and electrical metrics against operating tolerances.
| Physical / Chemical Property | Typical Metric Value | Test Methodology / Standard | Relevance to Da Nang Fab Processes |
|---|---|---|---|
| Chemical Purity (SiO₂ Content) | ≥ 99.99% (4N) | ICP-MS Spectrometry | Prevents donor/acceptor drift in semiconductor silicon |
| Density | 2.20 × 10³ kg/m³ | ASTM C693 | Determines structural weight load on cantilever furnace paddles |
| Coefficient of Thermal Expansion (CTE) | 5.5 × 10⁻⁷ K⁻¹ (20°C – 320°C) | Dilatometry (ASTM E228) | Maintains dimensional stability during cyclic heat steps |
| Annealing Point | 1215°C ± 10°C | Beam Bending (ASTM C598) | Relieves residual fabrication stress before assembly delivery |
| Strain Point | 1120°C ± 10°C | ASTM C598 | Defines upper limit for creep deformation under mechanical load |
| Softening Point | 1683°C | ASTM C338 | Protects structural wall integrity under localized plasma heating |
| Refractive Index (nD at 589.3 nm) | 1.4585 | Optical Interferometry | Vital for inline optical pyrometry and UV window transmission |
| Dielectric Strength (20°C, 1 MHz) | 25 – 40 kV/mm | Dielectric Breakdown | High-voltage insulation inside RF plasma and CVD reactor systems |
| Hydroxyl (OH⁻) Ion Concentration | ≤ 20 ppm (Standard) / ≤ 2 ppm (Treated) | FTIR Spectroscopy (2.73 μm) | Prevents devitrification acceleration in Central Vietnam's high humidity |
Devitrification Phenomenon in Humid Climates: Natural fused quartz resides in a meta-stable amorphous phase. In equatorial and tropical coastal climates like Da Nang, surface atmospheric moisture combined with trace airborne alkaline dust (Ca, Na) accelerates high-temperature crystallization into alpha-cristobalite above 1150°C. Zelvo Quartz implements high-purity chemical etching (HF/HNO₃) followed by 1000°C oxygen-purged bake-out to eliminate surface micro-contaminants, extending service life by over 35% in tropical coastal environments.
Application Scenarios Across Central Vietnam's Industrial Parks
Zelvo Quartz delivers custom-machined fused silica solutions configured for the unique operational environments of Da Nang's expanding high-technology manufacturing base.
1. Da Nang Hi-Tech Park: Semiconductor LPCVD & Thermal Oxidation
Inside the microelectronics fabrication and packaging facilities within the Da Nang Hi-Tech Park (Hoa Lien Commune, Hoa Vang District), fused quartz furnace tubes serve as the cleanroom process vessel for Low-Pressure Chemical Vapor Deposition (LPCVD), thermal drive-in, and dry/wet silicon wafer oxidation.
Operating alongside major automated diffusion furnaces, our tubes integrate custom flame-welded quartz injector nozzles, thermocouple wells, and nitrogen/argon gas purge manifolds. High geometric concentricity ensures vacuum-tight sealing with stainless steel water-cooled endcaps, eliminating atmospheric oxygen back-streaming during sub-torr processing.
- Silicon Wafer Processing Sizes: 4-inch, 6-inch, 8-inch, and 12-inch boats
- Low Bow Tolerances: Camber deviation ≤ 1.0 mm per 1,000 mm span
- Leak Integrity: Helium mass spectrometer verified (< 1 × 10⁻⁹ mbar·l/s)
2. Photovoltaic Wafer Diffusion & Annealing (Central Vietnam Solar Hub)
Central Vietnam's renewable energy corridor—stretching from Da Nang through Quang Nam and Quang Ngai—hosts Tier-1 solar cell and module production lines. In Phosphorus Oxychloride (POCl₃) liquid-source diffusion and Boron diffusion for advanced TOPCon and Heterojunction (HJT) N-type solar cells, large-bore quartz furnace tubes (outer diameters ranging from 250 mm to 380 mm) operate 24/7.
Zelvo's heavy-wall fused quartz tubes resist mechanical sagging under dynamic payloads exceeding 400 silicon wafers per batch cycle. Our specialized flame-polishing technique vitrifies the inner bore, resisting corrosive phosphorus-silicate glass (PSG) etching during production runs.
- Large Diameter Capabilities: Standard sizes OD 290mm, 330mm, 350mm
- Resistance to Heavy Chemical Corrosives: POCl₃, BBr₃, HCl, HF vapor
- Thermal Uniformity: Enables ±1.5°C zone consistency along furnace length
3. University & Materials R&D Laboratories (DUT & Research Centers)
Institutions such as the University of Science and Technology – The University of Danang (DUT), together with regional government quality-assurance testing laboratories, rely on precision quartz vessels for advanced chemisorption, X-ray diffraction (XRD), BET specific surface area analysis, and high-pressure chemical synthesis.
Custom twin-bore BET analysis tubes, zero-background XRD cavity sample plates, and high-pressure quartz ampoules provide analytical clarity. The materials exhibit near-zero background interference, enabling accurate characterization of porous catalytic materials, graphene powders, and battery anodes.
- Quantachrome & Micromeritics Port Compatibility
- Zero-Background Diffraction: Oriented optical quartz plates
- Flexible Prototyping: 1-piece custom drawing fabrication
4. Industrial Heating & Optoelectronic Device Curing
Within the Hoa Khanh and Lien Chieu Industrial Parks, manufacturing plants focused on surface-mount technology (SMT), LED encapsulation, and optical fiber patch assemblies utilize infrared quartz heating elements, twin-bore quartz guide tubes, and UV quartz protection sleeves.
High optical transmission (over 92% through the deep ultraviolet from 254 nm and across the near-infrared spectrum to 2500 nm) allows efficient thermal transfer while shielding sensitive heating alloys and UV lamps from corrosive flux vapors and harsh washouts.
- UV Transmission Efficiency: ≥ 90% at 254 nm
- Boring Options: Single bore, Twin bore, and Triple bore designs
- Surface Options: Clear fire-polished or diffused sandblasted
Central Vietnam's High-Tech Evolution & Quartz Sourcing Demands
Strategic economic factors driving modern supply-chain decisions for quartz glass furnace consumables across Da Nang and adjacent technology zones.
The "China+1" Transition & Near-Shore Supply
Global semiconductor giants and tier-2 assembly suppliers are diversifying physical plants into Central Vietnam. However, local supply ecosystems for high-purity quartz melting and machining remain limited within Vietnam. By establishing a direct, reliable logistics channel with Zelvo in Donghai (China's quartz capital), Da Nang plants bypass intermediary trader markups while securing rapid factory-level drawing turnaround.
Lien Chieu Port & Air Freight Integration
With the rapid expansion of Da Nang International Airport (DAD) and the progression of the new Lien Chieu Deep-Sea Port, transit times for sensitive quartzware have dropped substantially. Standard express consignments arrive within 3–5 working days, while bulk sea containers clear Tien Sa Port smoothly under ASEAN-China Free Trade Agreement (ACFTA) Form E preferential tariffs.
Sub-Fab Cleanroom Customization Needs
Standard off-the-shelf catalog tubes rarely integrate seamlessly into retrofitted diffusion stacks or specialized Japanese and European OEM furnace racks (e.g., Koyo Thermo, ASM, TEL). Da Nang engineers increasingly demand customized drawing revisions—integrating ground joint tapers, welded spiral gas coolers, and reinforced flanged bases—achievable only through agile manufacturers offering low MOQs.
End-to-End Processing: From High-Purity Silica Sand to Finished Tubes
Combining traditional artisan flame working with CNC 5-axis ultrasonic machining and laser cutting to meet the most exacting semiconductor tolerances.
1. Electric Arc & Gas Fusion
Donghai natural quartz sand is purified via acid leaching, flotation, and magnetic separation before melting in continuous electric vacuum furnaces at over 2000°C. This guarantees minimal bubble counts and micro-inclusion density.
2. Cold Mechanical Machining
High-speed water-cooled diamond saws, CNC ultrasonic milling centers, and optical core drills produce laser-precise slotting, wafer carrier notches, precision chamfers, and through-holes without micro-chipping or subsurface micro-fissures.
3. Hot Flame Glassblowing
Our senior master glassblowers—with over a decade of hands-on specialty experience—perform oxy-hydrogen lathe welding, quartz dome caps, flange fusion, and U-bends under temperature-monitored pyrometric control.
4. De-Stressing & Chemical Polish
Finished components undergo full thermal annealing at 1150°C in programmed programmable kilns to eliminate structural strain, followed by cleanroom HF etching, DI water rinsing, and cleanroom vacuum poly-bagging.
Procurement & Technical FAQ for Da Nang Industrial Buyers
Everything procurement officers, factory maintenance heads, and process engineers need to know about sourcing, importing, and operating fused quartz hardware in Vietnam.
What are the lead times and shipping routes for custom quartz furnace tubes delivered to Da Nang?
Standard dimensional tubes (OD 50 mm – 200 mm) without intricate flanging ship from our facility within 3 to 5 business days. Custom-engineered configurations—such as tubes with welded KF/ISO flanges, thermocouple access wells, or slotted wafer carriers—require 7 to 12 business days for precision machining and post-weld annealing.
For urgent cleanroom replacements in Da Nang Hi-Tech Park, we utilize prioritized air express (DHL/FedEx/SF International) direct to Da Nang International Airport (DAD), offering 2 to 4 days transit time including airport customs handling. For routine bulk procurement (e.g., complete horizontal furnace rebuild lots), sea freight is consolidated and routed to Tien Sa Port / Lien Chieu Port, typically arriving within 7 to 10 days from Lianyungang/Qingdao ports.
How does 99.99% SiO₂ fused quartz withstand devitrification under Central Vietnam's humid conditions?
Devitrification (the transformation from amorphous fused silica to white, crystalline cristobalite) occurs when surface impurities interact with ambient moisture at operating temperatures above 1150°C. Central Vietnam experiences high relative humidity year-round (averaging 75% to 85%), which can accelerate crystal nucleation if bare hands touch tube surfaces or if cooling air contains unconditioned particulate matter.
Zelvo addresses this through strict cleanroom hot-acid decontamination and ultra-smooth flame polishing, which minimizes surface micro-pores where airborne salts can settle. We provide comprehensive cleanroom SOPs for Da Nang fab operators, advising periodic 5% HF solution acid washes followed by high-purity ethanol drying to sustain optical clarity and structural resilience for thousands of heating hours.
Can Zelvo manufacture replica replacement quartz tubes for Japanese, European, or US furnace OEMs?
Yes. Many semiconductor assembly and photovoltaic plants operating in Vietnam face long OEM lead times (frequently 16–26 weeks) and high replacement costs when procuring from legacy furnace makers such as Tokyo Electron (TEL), ASM International, Koyo Thermo Systems, Bruce Technologies, or Centrotherm.
Clients simply provide a 2D PDF drawing, 3D STEP file, or an intact physical sample. Our engineering team measures critical dimensions (OD, wall thickness, camber, flange pitch, ground taper angles) using optical comparators and CMM equipment. We then fabricate drop-in replacement quartz furnace tubes that match or exceed original OEM specifications at a fraction of the cost and with turnaround times under two weeks.
What customs documentation and import certifications are provided for Vietnam import clearance?
We provide full export documentation to ensure immediate, zero-delay customs clearance through Vietnamese Customs (Cục Hải quan Thành phố Đà Nẵng). Key shipping packages include:
1. Certificate of Origin (Form E): Issued under the ASEAN-China Free Trade Agreement, allowing buyers to benefit from preferential 0% or reduced import tariff schedules.
2. Commercial Invoice & Detailed Packing List: Correctly harmonized under HS Code 7002.31.00 (Tubes of fused quartz or other fused silica) or 7017.10.00 (Laboratory, hygienic or pharmaceutical glassware of fused quartz).
3. Certificate of Analysis (CoA): Detailing ICP-MS trace metal impurity limits, dimensional tolerance verification, and thermal annealing certification.
What packaging methods are utilized to eliminate micro-fractures during maritime or air transit?
Quartz furnace tubes exceeding 1500 mm in length or 200 mm in diameter are vulnerable to resonant vibration during air transit and intermodal container handling. To ensure safe delivery, we employ custom packaging:
Every tube is cleaned, sealed in dust-proof antistatic PE film, and suspended in multi-layered high-density custom-cut Polyethylene (EPE) shock-absorbing foam saddles. The foam core is then floated inside an internal heavy-duty carton, which is packed into a heat-treated, fumigated plywood export crate (ISPM 15 compliant) secured with steel corner brackets. External impact sensors (ShockWatch) and tilt indicators (TiltWatch) are affixed to confirm proper handling throughout transit.
What is the Minimum Order Quantity (MOQ) for non-standard prototype quartz designs?
Our production floor maintains an agile MOQ of 1 piece for all customized quartz furnace tubes, process vessels, bell jars, and specialized laboratory apparatus. We understand that R&D centers, university engineering departments, and pilot testing lines at Da Nang Hi-Tech Park require single-unit proof-of-concept testing before committing to volume fabrication. Small-format consumables like BET twin-bore sample tubes carry a modest MOQ of 10 pieces.
What are the key differences between transparent fused quartz and synthetic fused silica?
Transparent Fused Quartz (Natural): Manufactured by fusing natural high-purity Donghai crystalline silica sands. It offers exceptional mechanical stability, high softening points (1683°C), and resistance to thermal sag, making it ideal for tube furnaces, diffusion barriers, thermocouple sheaths, and standard wafer carriers.
Synthetic Fused Silica: Produced via chemical vapor deposition (CVD) through the flame hydrolysis of silicon halides (SiCl₄). This results in extreme purity (>99.9999% SiO₂) with virtually zero metallic contaminants and deep UV transmission down to 193 nm. However, it exhibits a slightly lower viscosity and softening point compared to natural fused quartz, making synthetic material better suited for excimer laser optical windows and deep-UV photomasks rather than structural furnace tubes.
What is the recommended cleaning protocol before installing a new tube in a diffusion furnace?
Before loading into high-temperature process stacks, tubes must be cleaned to eliminate transit residues and airborne oils:
1. Wipe the exterior and interior with electronic-grade Isopropanol (IPA) or high-purity ethanol using non-linting cleanroom wipes.
2. For semiconductor-grade diffusion, immerse or flush with a 5% to 10% Hydrofluoric Acid (HF) bath for 3 to 5 minutes to strip the surface oxide layer.
3. Rinse thoroughly with ultra-pure deionized (DI) water until resistivity reaches 18 MΩ·cm.
4. Dry under clean nitrogen gas (N₂) purge.
5. Ramp up gradually inside the furnace at a rate of 5°C/min up to 800°C under continuous nitrogen purge before process gas introduction.
Your Direct Manufacturing Partner in High-Purity Quartz Glass
Headquartered in Donghai County—the crystal capital of China—Lianyungang Zelvo Quartz Products Co., Ltd. combines premier raw material reserves with precision fabrication capabilities.
Donghai Raw Material Direct Access
We source raw quartz rock from Donghai, Jiangsu Province, China's foremost quartz deposit. This provides complete supply chain oversight from raw mineral grading to final optical-grade tube drawing, eliminating intermediate broker price inflations.
Rapid 2-Hour Drawing Feasibility Review
Our sales engineering team is composed of seasoned glass technicians who evaluate CAD prints within 120 minutes during work hours. We provide actionable feedback on structural radius limits, wall thicknesses, and tolerance optimizations to simplify fabrication.
Pre-Shipment Quality Inspections
Before any crate departs our facility, components undergo rigorous quality checks: polariscopic stress inspection for residual thermal strains, laser-gauged concentricity profiling, and visual darkroom checks for inclusions. Detailed QA photo dossiers are provided with every shipment.
Plan Your Next Quartz Furnace Build With Zelvo
Whether replacing high-temperature diffusion tubes in Da Nang Hi-Tech Park, sourcing custom twin-bore BET reaction tubes for laboratory analyses, or engineering large-diameter process chambers, our technical engineering team is ready to assist.