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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.
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 |
100 mm |
±0.25 mm |
|
Thickness T.mm |
0.50 mm |
±0.03 mm |
|
Reference Flat F1,mm |
32.0 mm |
±2.50 mm |
|
Secondary Flat F2, mm |
11.0mm |
±2 00 mm |
|
SURFACE |
|||
Front Surface Finish |
Polished Ra < 0.7 nm |
||
Back Surface Finish |
Lapped, 0.4 pm < Ra < 0.6 μm |
||
Flatness |
< 10 μm |
||
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 |
Rounded edqe |
||
Lanqasite Wafer, YXIs/0/140/25 |
Tolerance |
|
|
Cut, A1 |
140° |
±0 1° |
|
Cut, A2 |
25° |
±0 1° |
|
Diameter D mm |
76 mm |
±0.25 mm |
|
Thickness T,mm |
0.50 |
± 0.03 mm |
|
Reference Flat F1,mm |
22.0 mm |
±2.50 mm |
|
Secondary Flat F2, mm |
11.0mm |
±2.00 mm |
|
SURFACE |
|||
Front Surface Finish |
Polished Ra <0.7 nm |
||
Back Surface Finish |
Lapped, 0 4 prn < Ra < 0 6 μm |
||
Flatness |
< 10 μm |
||
Front Surface Defects |
|||
Scratches, cracks, contamination, others (dimples, pits, oranqe 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 |
Rounded edqe |
||
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 |
100 mm |
±0.25 mm |
|
Thickness T,mm |
0.50 mm |
±0.03 mm |
|
Reference Flat F1,mm |
22.0 mm |
±2.50 mm |
|
Secondary Flat F2, mm |
11.0mm |
±2.00 mm |
|
SURFACE |
|||
Front Surface Finish |
Polished Ra O.7 nm |
||
Back Surface Finish |
Lapped, 0 4 μm < Ra < 0 6 μm |
||
Flatness |
<10 μm |
||
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 |
Rounded edqe |
||
Langasite Wafer, YXIs /0/138.5/26.7 |
Tolerance |
| |
Cut, A1 |
138.5° |
±0.1° |
|
Cut, A2 |
26.7° |
±0.1° |
|
Diameter D mm |
76 mm |
±0.25 mm |
|
Thickness T mm |
0.50 mm |
±0.03 mm |
|
Reference Flat F1, mm |
32.0 mm |
±2 50 mm |
|
Secondary Flat F2, mm |
11.0mm |
±2 00 mm |
|
SURFACE |
|||
Front Surface Finish |
Polished Ra < 0.7 nm |
||
Back Surface Finish |
Lapped, 0 4 μm < Ra < 0.6 μm |
||
Flatness |
<= 10 μm |
||
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 |
Rounded edqe |
||
Roditi International 2007