Vol.1 Technical Information
Inverted Mesa Blank
Fundmental High Frequency
The oscillating frequency of AT cut crystal unit which vibrates in a thickness shear mode is determined by the thickness of the blank. The blank is thinner, the frequency is higher. The blank is thicker, the frequency is lower.
- Relational expression of At cut blank and frequency ;
- F0 = 1.67 × N/T
- F0 = Oscillating frequency(MHz)
- N = Oscillation mode(1, 3, 5・・・)
- T = Thickness(mm)
To obtain very high frequency at fundamental tone it is necessary to prepare very thin blank. But if too thin, it becomes physically very weak, and it was very difficult to handle at the traditional processing method.
KDK has achieved very thin blank by the dry etching processing method using the magnetron plasma.
Since the inverted MESA blank by this method is processed very thin only in the center area, the not-etched around area remains at same thickness and physically strong.
The inverted MESA blank is used at our very high frequency crystal unit, VCXO and oscillator.
So far we have developed up to 250MHz at fundamental tone in the volume production, and aim much higher frequency.
Dry Etching Process
We have realized to achieve very thin blank by the plasma etching equipment developed our own in house. This method is already patented. (The dry etching method using the magnetron plasma : Crystal etching method Patent No. 3492933)
Mesa Blank Data
