TOKEN What is a Piezo-Ceramic What is a Piezo-Ceramic Some of the piezoelectric crystal can be calcined into the polycrystal ceramics, though there is a spontaneous polarization in each of the fine crystals in the piezoelectric ceramics which is cancelled as a whole and shows no piezoelectricity. But when a high D.C. voltage is applied to such ceramics, the directions of the spontaneous polarizations are brought to an uniformity and a ferroelectricity ceramics is attained. With some additives, the material with extremely stable frequency, temperature and aging characteristics is being used by TOKEN for ceramic filter. Compared with the single crystal, the piezoelectric ceramics has various advantageous features as follows : 1. Can be mass-produced at low cost. 2. Can be formed into any desirable shape. 3. The direction of the polarization is easily attainable. 4. Chemically and physically stable. 5. Easy for fabrication. Ceramic resonators use the mechanical resonance of piezoelectric ceramics. The oscillation mode varies with resonant frequency. The table on the right shows this relationship. As a resonator device, quartz crystal is well-known. RC oscillation circuits and LC oscillation circuits are also used to produce electrical resonance. The following are the characteristics of PIEZO-CERAMIC. Version 2010 http://www.token.com.tw/ rfq token.com.tw 01 of 03 TOKEN What is a Piezo-Ceramic 1. High stability of oscillation frequency stability is between that of the quartz crystal and LC or RC oscillation circuits. The temperature coefficient of quartz crystal is 10–6/°C maximum and approximately 10–3 to 10–4/°C for LC or RC oscillation circuits. Compared with these, it is 10–5/°C at –20 to +80°C for ceramic resonators. 2. Small configuration and light weight The ceramic resonator is half the size of popular quartz crystals. 3. Low price, non-adjustment PIEZO-CERAMIC is mass produced, resulting in low cost and high stability. Unlike RC or LC circuits, ceramic resonators use mechanical resonance. This means it is not basically affected by external circuits or by the fluctuation of the supply voltage. Highly stable oscillation circuits can therefore be made without the need of adjustment. 00 00 Flexural mode Length mode Area expansion mode Radius vibration Shear thickness mode Thickness expander mode Surface acoustic wave [Note] : show the direction of vibration Ceramic Resonator Vibration Mode (Flexural mode, Length mode, Area expansion mode, Radius vibration, Shear thickness mode, Thickness expander mode, Surface acoustic wave) and Frequency Range 02 of 03 http://www.token.com.tw/ rfq token.com.tw Version 2010 TOKEN What is a Piezo-Ceramic The table briefly describes the characteristics of various oscillator elements. Name LC Characteristics of Various Oscillator Elements Oscillation Frequency Long-term Price Size Adjustment Initial Tolerance Stability Inexpensive Big Required ±2.0% Fair CR Inexpensive Small Required Quartz Crystal Expensive Ceramic Resonator Inexpensive Small Not required ±0.5% Big ±2.0% Not required ±0.001% Fair Excellent Excellent Back to 1st Page - What is a Piezo-Ceramic Version 2010 http://www.token.com.tw/ rfq token.com.tw 03 of 03