Langasite Wafers and Boules

• Attractive piezo-electric coupling
• Excellent temperature stability
• Prototype material available

Langasite wafers are substrates fabricated from single crystal langasite suitable for use in surface acoustic wave applications. Such wafers are most commonly specified as 3″ diameter with a reference flat. Wafer orientation is customer specified based on desired component performance characteristics. A high quality, low damage surface is prepared on one major (propagating) surface by polishing. The back side is usually lapped to a rougher finish to attenuate unwanted vibration modes.

Langasite Wafer Specifications

LGS 140-25-100/500

Langasite Wafer, YXIs /0/140/25		Tolerance
Cut, A1	138.5°	± 0.1°
Cut, A2	26.7°	± 0.1°
Diameter D mm	100mm	±0.25mm
Thickness T mm	0.50mm	± 0.03mm
Reference Flat F1, mm	32.0mm	± 2.50mm
Secondary Flat F2, mm	11.0mm	± 2.00mm
Surface
Front Surface Finish	Polished Ra < 0.7 nm
Back Surface Finish	Lapped, 0.4 pm < Ra < 0.6μm
Flatness	< 10μm
Front Surface Defects
Scratches, cracks, contamination, others (dimples, pits. orange peel)	No such defects by visual inspection
Chips
Edge chips Surface	Radial depth < 0.5mm: Peripheral chord length < 1.0mm No chips by visual inspection
Bevel	Round Edge

LGS 138.5-26.7-76/500

Langasite Wafer, YXIs /0/138.5/26.7		Tolerance
Cut, A1	138.5°	± 0.1°
Cut, A2	26.7°	± 0.1°
Diameter D mm	100mm	±0.25mm
Thickness T mm	0.50mm	± 0.03mm
Reference Flat F1, mm	22.0mm	± 2.50mm
Secondary Flat F2, mm	11.0mm	± 2.00mm
Surface
Front Surface Finish	Polished Ra < 0.7 nm
Back Surface Finish	Lapped, 0.4 pm < Ra < 0.6μm
Flatness	< 10μm
Front Surface Defects
Scratches, cracks, contamination, others (dimples, pits. orange peel)	No such defects by visual inspection
Chips
Edge chips Surface	Radial depth < 0.5mm: Peripheral chord length < 1.0mm No chips by visual inspection
Bevel	Round Edge