Glassy carbon (glassy carbon)

This page introduces precision processing of glassy carbon (glass-like carbon) performed at TDC.

What is glassy carbon?

Glassy carbon (glass-like carbon) is a black glass-like carbon material, and refers to a material that is carbonized by applying heat to resin.

It is widely used mainly in the semiconductor field due to its excellent stability even in vacuum at 3000°C and in air at 500°C, as well as excellent electrical conductivity.

Features of glassy carbon

Glassy carbon has the following characteristics.

• lightweight
• Has electrical and thermal conductivity
• Low coefficient of thermal expansion, excellent heat resistance, and high strength
• Excellent chemical resistance and corrosion resistance
• Highly airtight and impermeable to gases and liquids. gas impermeable
• high purity
• Does not generate dust such as carbon powder
• Degassing free
• Molten glass and molten metal do not adhere easily
• Dense isotropic structure without pores
• Smooth surface like glass

Advantages and disadvantages of glassy carbon

Glassy carbon has the following advantages and disadvantages.

Characteristics	Advantages	Diasdvantages(notes)
Corrosion resistance	It has high corrosion resistance against many chemicals.	In the atmosphere above 500°C, oxidation may occur.
Heat-resistant	It can withstand temperatures up to about 3,000°C in a vacuum.	If the material is stressed, plastic deformation begins in the region above 2,500°C. If heat is applied locally, it may lead to material damage.
Contamination prevention	Contamination by metal elements is almost non-existent.	Precision cleaning is essential as the material surface may become contaminated during processing and handling.
Prevention of dust generation	Because it is highly airtight and hard, it is possible to suppress dust generation compared to general carbon materials.	Not suitable for mechanical sliding parts as it is not self-lubricating.

Difference from quartz glass

Glassy carbon is often compared to silica glass because of its use in the semiconductor field and its properties.

When comparing quartz glass and glassy carbon in terms of physical properties, the following differences can be seen.

Characteristics	Glassy Carbon (glass-like carbon)	Quartz glass
Bulk density（kg/m3）	1,530	2,200
Flexural strength（MPa）	150	50
Young’s modulus（GPa）	23	73
Coefficient of thermal expansion（×10-6/℃）	3.7	0.5
Specific heat（J/gK）	0.75	0.8
Thermal conductivity（W/mK）	7	1.3
Heat resistance	great	ok
Electrical conductivity	high	none
Dust generation	none	none
gas permeability	none	none

Applications and industries of glassy carbon

Glassy carbon has excellent chemical resistance, electrical conductivity, and low gas permeability, so it is commonly used in the semiconductor field.

In addition, it is mainly used in the following industries and fields.

• Materials for semiconductor devices
• Liquid crystal parts
• Heat treatment jig
• Glass molding parts/parts
• substrate holder
• Heat shield plate
• Susceptor
• guide ring
• Etcher electrode
• cleaning material
• Dummy wafer (~400mm)
• glass molding member
• Crucible
• fuel cell electrode
• protective tube

For precision processing of glassy carbon (glass-like carbon), please contact TDC

TDC can handle precision processing of all types of glassy carbon using the polishing technology we have cultivated so far.

We also accept processing with precision that other companies refused. If you have any questions about glassy carbon processing, please feel free to contact TDC.

Example of precision processing of TDC’s glassy carbon (glass-like carbon)

Examples of precision processing of glassy carbon (glass-like carbon) at TDC are as follows. With our processing know-how according to the material and our accumulated polishing processing technology, we can handle any precision. Please feel free to consult with TDC for glassy carbon processing projects that have been rejected by other companies.

Precision machining example

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