Process |
Process Drawing |
Description of Process |
Cutting |
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With the r-surface of a lumbered crystal used as the reference. Wafer-shaped pieces are cut out at the prescribed angle. |
Measurement of angle |
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To confirm that the crystal is cut at the prescribed angle, the angle is measured by means of an X-ray angle checker. |
Precision lapping |
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Since frequency of AT-cut crystals is deter-mined by the thickness of the crystal piece, the thickness of the crystal pieces is made uniform by means of a surface lapping machine to raise the surface accuracy. |
Profiling |
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To prevent joining with other vibration modes and from being influenced by sub-vibrations, the external shape is properly corrected by profiling. |
Bevel |
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To cause vibrations to occur at the center, the crystal piece is shaped into the form of a lens. |
Etching & cleaning |
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After removing the worked layer produced by precision lapping and beveling by etching, cleaning is carried out. |
Electrode metal deposition |
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The electrode used for applying a electric field to the crystal piece is formed by vacuum metal deposition (Ag,etc.) on top of the crystal piece. |
Assembly |
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The crystal piece is secured to the base by such means as Ag paste, or soldering. |
Fine frequency adjustment |
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Final fine adjustment of the frequency is carried out, by performing vacuum metal deposition again while letting the crystal oscillate. |
Sealing |
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To suppress aging of the crystal piece, the inside of the holder is first made vacuum, or filled with such inactive gas N2, and then sealed with a cap. |
Completion inspection |
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The crystal pieces are inspected for their specifications including frequency deviation, frequency vs, temperature characteristics, equivalent resistance, hermetical of seal and insulating properties. |
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