Doubly Rotated Blanks
Doubly Rotated Blanks are single crystal cultured quartz blanks fabricated with a double angular rotation suitable for operation in the thickness shear mode. This family of blanks includes the SC-cut and IT-cut and is designed to reduce the effects of stress on resonant frequency.
Doubly rotated blanks can be fabricated to a range of specifications for either of the two angles of rotation as well as the overall blank dimensions. Typical specifications for the j -rotation (i.e. the first, or X to X', rotation) are around 22° for SC-cut blanks and 19° for IT-cuts, but can vary by as much as ±10. The q -rotation (i.e. the second, or Z to Z' rotation) typically ranges from 33° to 35°. Verification of specified orientation is assured by providing us with the appropriate x-ray diffraction reference standards. As the blanks are usually angle corrected after delivery, both surfaces are lapped to a rough finish using 15 µm abrasive, unless otherwise specified.
|X-height x Z-width||mm||16.5 x 16.5||± 0.25|
|Thickness, t||As specified||± 0.013|
|Orientation - φ||degrees||As specified (18°-24°)||± 10 minutes|
|Orientation - θ||degrees||As specified (33±-35°)||± 5 minutes|
|Standard dimensions (other dimensions are available to meet customer-specific requirements)|
|Infrared a (3500 cm-1)||α - units||Grade B: 0.045||maximum|
|Inclusions (diameter)||25 - 75 µm||cm³||4|
|75 - 100 µm||cm³||2|
|Etch Channels||cm²||Grade 4: 300||maximum|
|Twins in useful volume||Count||None|
- Surface Finish: rough lapped using 15 µm abrasive.
- Chips intruding onto surface: 1.0 mm Maximum
- Pure - Z, seed free material
International Electrotechnical Commission Standard, CEI/IEC 758, Second edition, 1994.
Institute of Electrical and Electronic Engineers Standard on Piezoelectricity, ANSI/IEEE Std. 176-1 987.