Vacuum Components
PBN (Monentive Performance Material)
Thin Film Deposition Thickness Rate...
Vacuum Measurement (THYRACONT)
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Crucible
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Pyrolytic Boron Nitride (PBN) is an anisotropic, high-temperature ceramic which exhibits a unique combination of high electrical resistance and good thermal conductivity. This non-toxic, non-porous compound is exceptionally pure by virtue of the synthesis process (high temperature/low pressure chemical vapor deposition). It can be deposited or easily machined into a limitless number of shapes, including:
- crucibles
- boats
- tubes
- bottles
- machined plate products
| PBN's directional thermal conductivity provides excellent "heat spreading" capability for improved temperature uniformity. The combination of high strength, good thermal conductivity, and a low coefficient of thermal expansion make the material extremely resistant to thermal shock.
PBN has found wide acceptance in the semiconductor, electronics, metallurgical, thin film, and pharmaceutical industries. |
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Applications include:
- Crucibles and boats for single crystal growth of compound semiconductors
- Crucibles and hardware for high temperature vacuum processes, e.g. MBE, aluminum evaporation, etc.
- Insulators in high temperature vacuum tubes
- Heating elements for silicon wafer processing equipment
- PBN-coated graphite susceptors, heat shields, nozzles and evaporation boats for military and industrial applications.
PBN's unique combination of chemical, electrical, thermal, and mechanical properties provide engineers an alternative material when designing hardware requiring the highest performance level.
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12 Reasons why PBN Belongs on Your Next Job
- Non-toxic
- High purity
- Low density
- Chemically inert
- Non-porous
- Highest dielectric strength known
- Good thermal conductivity
- Tensile strength increases with temperature
- Excellent thermal shock resistance
- High oxidation resistance
- Negligible outgassing
- Advantageous anisotropy (electrical, mechanical, and thermal)
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Typical Properties (R.T.)
| Property |
PBN |
| Apparent density, gm/cc |
1.95 ?2.22 |
| Tensile Strength, MPa (psi) |
40 (6,000) |
| Flexural Strenght, MPa (psi) |
80 (12,000) |
| Thermal Conductivity, W/m°C |
"ab" 60
"c" 2 |
| CTE, mm/mm/°C (1000°C) "ab" |
2x10-6 |
| Resistivity, ohm-cmc |
1015 |
| Dielectric Strength, D.C. volts/mmc |
2x105 |
| Dielectric Constant |
"ab" 5.2
"c" 3.4 |
| Total Metallic Impurities, ppm |
<10 |
| Outgassing |
Negligible |
| Max. suggested use (°C) |
2,500° |
Mechanical Properties
The tensile strength of PBN increases from 41 MPa at room temperature to 103 MPa at 2,200°C. The bend strength across the basal planes in the "a" direction is 83 MPa at room temperature.
The modulus of elasticity, or Young's modulus, value is 22 GPa at room temperature. Poisson's ratio is 0.25. The ultimate compressive strength is approximately 234 MPa.
Chemical Properties
PBN is inert to all reagents at room temperature and to a large number of reagents, metals, and compounds at temperatures from 1000°C to 2000° C. It is stable with graphite at 2200°C, most molten metals at their melting points, and can be exposed to oxygen indefinitely at temperatures up to 750°C.
Principal Bulk Impurities in PBN
| Impurity |
Measurement
Method |
ppm |
| Na |
SSMS (Spark Source Mass. Spec.) |
< 2 |
| Al |
SSMS (Spark Source Mass. Spec.) |
0.4 |
| Si |
SSMS (Spark Source Mass. Spec.) |
3 |
| Ca |
SSMS (Spark Source Mass. Spec.) |
3 |
| Fe |
SSMS (Spark Source Mass. Spec.) |
0.2 |
Click to view the structure of Pyrolytic BN
Thermal Properties
An excellent refractory material, PBN also exhibits excellent thermal conductivity in the deposition plane (ab) and is a thermal insulator through its thickness (c). This high degree of anisotropy (about 50:1) is found only in one other pure, solid material: pyrolytic graphite.
PBN is unmatched for thermal shock resistance. Plates can be heated to 2000°C and then plunged into cold water with no visible damage.
Electrical Properties
PBN exhibits extremely high electrical resistivity (yet is uniquely combined with good directional thermal conductivity) and the highest dielectric strength of any commercially available material. Its superior dielectric properties remain constant as temperatures increase ?even above 1000°C.
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