What is a crucible? N large selection of key experts will tell you

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The crucible is a cup-shaped vessel used in the laboratory. It is used to hold liquid or solid for high-temperature heating, because it does not react with most molten gold and compounds. OLED evaporation is a coating technology that uses resistance or electron beam heating to reach the melting temperature of the material to be evaporated under high vacuum conditions, so that atoms evaporate and reach and adhere to the surface of the substrate. In the OLED manufacturing process, evaporation is a necessary equipment, which is absolutely no stranger to the OLED industry, but do you know that there are many materials for crucibles? Today, I will introduce to you the advantages and disadvantages of the three common materials, and share the tips to know when choosing a crucible to help you find the most suitable crucible!
 

What is a crucible? What are the uses of crucibles?

Crucible is an evaporation process used in the manufacture of OLED panels. The evaporation process is an important key technology of the OLED process. The evaporation equipment is difficult to obtain and has become a threshold. In a vacuum chamber, the material to be vaporized is placed in a crucible, heated until it vaporizes and sublimates, and the gas adheres to the surface of the substrate placed nearby to form a thin film. The quality of the crucible has also become an important key to the process yield. Choosing an unsuitable crucible will cause the material in the crucible to be incompletely vaporized, fail to reach the boiling point required by the equipment, and fail to adhere to the surface of the substrate. In this case, it not only wastes time and manpower, but also the evaporation materials cannot be effectively used, which not only wastes materials, but also causes the process yield to deteriorate. Sometimes it must be done again, which increases the company’s raw material cost burden, so it has excellent quality The crucible is half the battle.
 

What materials are available for the crucible?

Ta (tantalum)

Tantalum is a hard blue-gray rare transition metal. It has high ductility, high temperature resistance, high chemical stability, and does not react with other compounds. It is resistant to hydrochloric acid, nitric acid, and has excellent acid resistance. It can resist acid corrosion and has strong anti-corrosion ability. It can even resist the erosion of aqua regia below 150 °C. It is a refractory metal and is often used as a minor component of alloys. Its chemical activity is low, tantalum has a high melting point, and can resist oxidation, so it can be used as a crucible material for vacuum evaporation parts. Many anti-corrosion parts require tantalum
 

Graphite Special Graphite

Graphite is a kind of crystalline carbon. The color is dark black, iron ink to dark gray. The melting point is 3652°C and the boiling point is 4827°C. It is soft, with fine bones on the surface, and conductive. It is chemically inactive, resistant to corrosion, and hard to react with acids and alkalis. It is often used to make crucibles. Graphite crucibles can prevent liquid and gas penetration, can withstand high temperatures, inhibit dust generation, and improve wear resistance.
 

PBN Pyrolytic Boron Nitride

Pyrolytic Boron Nitride (PBN) belongs to the hexagonal crystal system. The color of the product is ivory white, non-toxic. It is an advanced ceramic material with a purity of 99.999%, acid and alkali resistance, oxidation resistance, good thermal conductivity, good surface density and high temperature. No porosity and easy processing. It is formed by chemical vapor deposition (CVD) of ammonia and boron halides under high temperature and high vacuum conditions. It can be used to prepare PBN plates or crucibles directly.
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Comparison table of crucible material difference 

Crucible material Advantages Disadvantages Recommended temperature Standard large capacity
Graphite Inactive chemical properties Fragile 1500 ℃ 1000 cc
PBN acid and alkali resistant
Good surface density
Fragile 1500 ℃ 500 cc
Tantalum
(Ta)
resistant to hydrochloric acid and nitric acid Sturdy 1500 ℃ 500 cc


Crucible selection key points

Here are a few key points for choosing a crucible, which will affect the material usage rate in the crucible. How to make the material actually used on the OLED substrate is what every user cares about the most. The following is an introduction for you:
 

Key 1: The capacity, size and shape of the crucible

OLED crucibles are mostly cylindrical in shape, some are like rectangular boxes, and their sizes are different depending on the capacity. The capacity of OLED crucible is from 100ml to 500ml. We can customize it according to customer requirements. The most common encounter is to increase the capacity of the existing crucible, which can put more materials for evaporation, and sometimes change the shape. Improve the eruption port of the crucible to prevent the leakage of the evaporation material under high temperature conditions.
 

Key 2: Melted organic materials, specific metals

Depending on the vapor deposition process, the vapor deposition materials used are different. Generally, organic materials and metal materials are used in the OLED vapor deposition process.
 

Key 3: Operating temperature, vacuum degree

Depending on the evaporation material, the crucible that can be matched is different, because it needs to be heated to the boiling point required by the material. Not every material of the crucible can be matched. Choose the appropriate crucible according to the material characteristics, and the material can be fully evaporated. , And attached to the surface of the substrate, which is half the battle.


Key 4: Density and thermal conductivity of the crucible material

In the evaporation process, even if the appropriate material is selected, the crucible of the same material can be subdivided into many materials. Therefore, different manufacturers use different materials, even if the crucible of the same shape, the density and thermal conductivity of It is not the same. This also affects whether the material can be fully evaporated. It is important to choose a good crucible. The OLED evaporation process is half the success. The common materials and selection methods of the crucible will help you better choose the suitable one. Crucible, we provide Ti (titanium), graphite crucible, PBN three materials to choose from, can be customized according to your needs, we have rich experience and performance, and Japan ULVAC, Tokki, South Korea SUNIC, SELCO equipment can be Used together, and cooperated with many big brand customers, our business philosophy: focus on quality, optimize the surface of the substrate.


Conclusion

The insiders know that crucibles are very important. If you choose a good crucible, the OLED evaporation process is half the success. The common materials and selection methods of crucibles help you to better choose the suitable crucible. We provide Ti (titanium) and graphite. Crucible and PBN three materials can be selected, and can be customized according to your needs. We have rich experience and performance, and can be used with Japanese ULVAC, Tokki, South Korean SUNIC, SELCO equipment, and cooperate with many major brand customers , Our business philosophy: focus on quality, optimize the performance of customers' existing products, localized instant service, and provide PBN crucibles, Ti (titanium) crucibles, graphite crucibles, and OLED crucibles if available in the OLED field. If necessary, please contact us.
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