GD-FHT™
OHARA's GD-FHT™ is a glass disk for use in flying height testers.
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OHARA's GD-FHT™ is a glass disk for use in flying height testers.
Product Introduction
OHARA’s GD-FHT™ is a glass disk for use in flying height testers. It contributes to the decrease of static breaking in the magnetic head, both in manufacturing and R&D. This obvious advantage is due to the superior electrical properties of GD-FHT™ compared to conventional products, such as S-BSL7 and Synthetic Fused Silica. As the glide height of the magnetic head is lowered, we offer our “smooth type” GD-FHT which is an extremely precise, super smooth and ultra-clean disk. OHARA’s GD-FHT™ is transparent with the same mechanical strength as conventional products.
Feature
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01Antistatic Effect
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02Transmittance and mechanical properties equivalent to synthetic quartz glass
Physical properties
| Properties | GD-FHT™ | Conventional Materials | ||
|---|---|---|---|---|
| S-BSL7(BK7) | Synthetic Fused Silica | |||
| Electrical Properties | Volume Resistivity* (Ω·cm) | 1.1×1011 | 1.0×1015 | 1.0×1019 |
| Surface Resistivity*** (Ω·□) | 4.4×1012 | 1.0×1015 | 8.6×1014 | |
| Charging Voltage*** kV | 0.05 | 2.6 | 3.1 | |
| Half Decay Period*** (s) | 8.9 | >30min | >30min | |
| Mechanical Properties | Knoop Hardness** Hk | 590 (6) | 570 (6) | 640 (6) |
| Abrasion** | 53 | 94 | 59 | |
| Young’s Modulus (GPa) | 82 | 80 | 71 | |
| Rigidity Modulus (GPa) | 33 | 33 | 31 | |
| Bending Strength (MPa) | 107 | 64 | 69 | |
| Poisson’s Ratio | 0.22 | 0.21 | 0.17 | |
| Thermal Properties | CTE 10-7/K | 33 | 72 | 5.5 |
| *Measured at 20°C and Humidity of 60% according to JIS K 6911. **Measured according to JOGIS (Japan Optical Glass Industry Association standard) ***Measured referring to JIS L 1094 (OHARA’s original method). ※Half decay period is the time required for the charging voltage of the surface to half of its initial value. |
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| Transmittance (%) | Wavelength nm | 400 | 500 | 600 | 700 |
|---|---|---|---|---|---|
| 2.45mmt | 89.8 | 91.4 | 91.6 | 92.0 | |
| 2.76mmt | 89.8 | 91.3 | 91.6 | 92.0 | |
| 4.35mmt | 88.5 | 90.9 | 91.3 | 91.6 | |
| 6.44mmt | 87.4 | 90.7 | 91.3 | 91.6 | |
| Refractive Indices | 436nm | 1.539 | |||
| 486nm | 1.534 | ||||
| 546nm | 1.530* | ||||
| 588nm | 1.528 | ||||
| 633nm | 1.526* | ||||
| 656nm | 1.525 | ||||
| *Calculated Value n=0.00482/λ2+1.51362 n: Refractive Index λ: Wavelength(μm) | |||||
| Specifications | Outer Diameter mm | 48-133 |
|---|---|---|
| Inner Diameter mm | 5-10 | |
| Thickness mm | 2-8 | |
| Concentricity μm | ≦5-10 | |
| Roundness of Inner iameter μm | ≦5-10 | |
| Parallelism μm | ≦5-10 | |
| Flatness μm | ≦0.5 | |
| Roughness Rmax nm | ≦2.5-4.0 |
Properties subject to change along development.
Application example
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Semiconductor Related
