PBNvalues describe: PBN
Semiconductor equipment & lithographyBig science (accelerators, light sources, public fusion)
Why it wins
The crucible of epitaxy: CVD-grown, binder-free, nothing to outgas into an MBE melt. Effusion cells, coating boats, high purity liners.
Why not the alternative
Graphite crucibles shed carbon into III-V melts; alumina reacts with aggressive charges.
Watch out
Anisotropic: strong in plane, cleaves between layers.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated.
Provisional provenance: CoorsTek, CeramTec, Kyocera technical ceramic data.
Wet cleaning
| Recipe | solvent wipe and dry only |
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| Forbidden | aqueous cleaning of a heater assembly: any trapped moisture is fatal at power |
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| Limit | the CVD deposit is pore-free, so cleaning is a wipe, not a process |
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Vacuum and outgassing
| Outgassing, unbaked (10 h) | 5e-10 mbar·L/s/cm² |
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| Outgassing, baked | 5e-13 mbar·L/s/cm² |
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| Vapour pressure | none |
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Temperature
| Bake, assembled | 450 °C |
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| Vacuum degas | 1400 °C |
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| Braze / H2 firing | 1600 °C |
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| Metallurgical limit | stable to 2000 °C in vacuum or inert |
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Thermal
| CTE | 1.0 in-plane, 20 through ppm/K |
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| Thermal conductivity | 60 in-plane, 2 through W/m·K |
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| Specific heat | 800 J/kg·K |
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| Emissivity | 0.9 |
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| Melting / softening | 2973 sub. °C |
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Mechanical
| Strength | 150–200 flex MPa |
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| Elongation | nil |
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| Young's modulus | 25–50 GPa |
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| Density | 2.15 g/cm3 |
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Electrical and magnetic
| Relative permeability | 1.0 |
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| Resistivity | >1e14 Ω·cm |
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| Dielectric strength | 50–100 kV/mm |
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Engineering
| Corrosion | inert; unlike hot-pressed BN it is not hygroscopic |
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| Joining | clamped or CVD-integrated with graphite heaters |
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| Process notes | the pore-free crystalline form; do not confuse it with hot-pressed BN |
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| Availability and cost | Momentive, to drawing |
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Grades
| PBN (CVD) | effusion cells and liners |
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| PBN/PG composite heaters | integrated heater-crucible stacks |
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Sources · 1
- Momentive PBN data
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