Boron nitride (BN) and tungsten are 2 of the most commonly used and popular materials for industrial evaporation boats. With different mechanical, chemical and thermal properties, both of them fit different manufacturing processes.
In this guide, we discuss their differences, pros and cons, and suitable applications. You will get clear guidance to pick the ideal evaporation boat for your specific production line.
Overview of BN & Tungsten Evaporation Boat
Evaporation boats are indispensable consumables for vacuum thermal evaporation and PVD coating processes. BN and tungsten materials bring different performance. Let’s see!
Boron Nitride (BN) Evaporation Boat
BN ceramic boats are made of high-purity hexagonal BN composites. Most industrial-quality BN boats contain a little TiB2 that exhibits low vapor pressure and good chemical inertness. It can help to balance the conductivity and stability of BN boats.
BN boats show stable performance under 1,800℃ high temperatures. It also does not wet molten metals like aluminum, silver and gold, making it perfect for high-precision coating production to meet its strict purity requirements.
Pure Tungsten Evaporation Boat
Tungsten boats are forged from high-purity tungsten metal,[1] which holds the highest melting point of 3,422℃ among all industrial metals. It also boasts excellent high-temperature mechanical strength and thermal conductivity.
Tungsten boats utilize its metal conductivity to heat and evaporate. They feature a simple structure and strong pressure resistance, widely used in traditional high-temperature evaporation processes.
Further Reading: What is an Evaporation Boat? Guide to Ceramic Evaporation Boats for Industrial Coating & Metallization
BN & Tungsten Evaporation BoatPerformance of BN & Tungsten Evaporation Boat in Industrial Applications
We compare across 6 dimensions that matter most to your manufacturing. Read to learn their performance gaps and select the most suitable one!
High-Temperature Stability
Temperature changes are common in cyclic vacuum production. As a result, you need evaporation boats that can keep shapes under repeated cycles of heating and cooling.
BN ceramic boats excel in thermal shock resistance. They resist deformation and cracking even under frequent temperature cycling.
Although tungsten boats have a higher melting point, continuous heating makes tungsten brittle and prone to warping, causing deformation. You need frequent replacement to avoid unevenness.
Chemical Stability
Coating contamination is one of the top causes of defective products. A stable chemical property ensures film layer purity.
BN evaporation boats feature high chemical stability. They do not react with molten metals or metal vapor in vacuum environments, leaving 0 impurity to pollute your coating.
Tungsten boats have moderate corrosion resistance. They will react with active metals under long-term high heat and only work stably for common metal evaporation. Even tiny tungsten compounds can cause changes in film color and impurity.
Metal Adhesion
Material adhesion on boat walls will disrupt uniform evaporation and increase your maintenance workload.
BN ceramic surfaces are non-wetting for almost all molten evaporants. Metal materials barely stick to the boat inner wall. Its anti-adhesion performance saves your time and labor costs.
Tungsten surfaces have weak metal adhesion resistance, so molten metals gradually adhere and accumulate on the inner wall, causing uneven heating.[2] You have to stop production regularly for cleaning, and this will increase your time and labor costs.
Service Life & Cost
Long-lasting durability effectively reduces your downtime and replacement frequency.
BN evaporation boats possess anti-corrosion and anti-adhesion properties to slow down wear, providing a longer average service life in precision coating. They support continuous mass production with low comprehensive consumption.
In contrast, tungsten boats have lower single-piece purchase costs. But their deformation and metal corrosion lead to frequent replacements. Your long-term operating cost will be higher, especially for high-frequency production.
Vacuum Adaptability
High-vacuum conditions need low-outgassing consumables; otherwise, excessive gas release can ruin vacuum degree and coating quality.
High-density BN ceramic boats release almost no gas during heating. They perfectly adapt to high-precision high-vacuum evaporation processes.
Tungsten metal may release trace absorbed gas at extremely high heat. It fails to meet ultra-high-vacuum process standards, only fitting conventional medium-vacuum production.
Customization Flexibility
Different production lines need customized boat sizes and groove shapes.
BN ceramics are hard and brittle. Custom shapes require mature ceramic sintering technology. They suit standardized fixed-size production.
Tungsten boats have good machinability. You can customize special grooves, thicknesses and sizes easily. They adapt to diverse non-standard evaporation equipment.
Suitable Application for BN & Tungsten Evaporation Boat
Here, we sort their most applicable industrial uses. You can make an accurate selection by matching their traits with your production requirements.
When to Choose Boron Nitride Evaporation Boats?
If your production requires long-term continuous operation and zero coating contamination, BN boats are your priority choice.
BN ceramic boats are ideal for all high-precision, high-purity coating processes.
They deliver stable quality and low maintenance, working best for optical film coating, semiconductor wafer evaporation and precious metal evaporation. They also fit reactive evaporation and PECVD processes with strict purity demands.
When to Choose Tungsten Evaporation Boats?
If you need custom boats with special shapes, and have strict budget control,[3] tungsten boats are more suitable.
Tungsten boats are ideal for conventional high-temperature evaporation with ordinary purity requirements.
They offer high cost performance for standard processes, suiting common metal evaporation, decorative coating and low-to-medium precision industrial film production. Their excellent high-temperature strength fits ultra-high temperature evaporation processes beyond BN’s tolerance.[1]
FAQs
Can boron nitride evaporation boats replace tungsten boats completely?
No. BN boats cannot withstand temperatures above 1,800℃. Tungsten boats are still irreplaceable for ultra-high-temperature evaporation.
Why do precision optical coatings prefer BN ceramic boats?
BN boats have zero metal precipitation and low outgassing. They avoid tiny impurity spots on optical films and ensure high light transmittance.
Do tungsten boats need pre-treatment before use?
Yes. You need high-temperature degassing to remove absorbed gas. This prevents vacuum degree drop and coating bubbles during production.
What causes BN boat damage in production?
Most comes from violent thermal shock and mechanical collision. Slow temperature rise and stable operation extend its service life greatly.
Which boat saves more cost for mass continuous production?
BN boats. Their long service life and low maintenance offset their higher single-piece price, providing lower comprehensive costs.
Can BN boats evaporate high-melting-point metals?
They work for most conventional metals. For metals needing over 1,800℃, tungsten boats are the viable option.
How to store evaporation boats to extend their shelf life?
Store both boats in dry, dust-free environments. Keep tungsten boats away from moisture and oxidation, and avoid surface scratches.
Conclusion
You only need to match the evaporation boat to your process precision, temperature and scale. A targeted choice will effectively optimize your product quality and overall production costs.
Newthink New Materials is a professional ceramic evaporation boat manufacturer and provider. Contact us for detailed information.
Thanks for your reading. Hope this article will be helpful.
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