ITC has handled many crystal units (microprocessor, control device, citizen band, marine band, monitor band, TV, VTR set etc.) for over 20 years. Also we have made an effort in developing military high stability crystal units. ITC's well developed technique of mass production enables you to use these crystal units at low cost.
Specifications
- Temperature test, temperature cycling test:
- Conditions, steps of cycle: at -55 Celsius, 30 minutes; at +25 Celsius, 10~15 minutes; at +85 Celsius, 30 minutes; at +25 Celsius, 10~15 minutes. Number of cycles 3 times
- Results: frequency and wave form of tested products must remain within specifications
- Temperature test, thermal shock test:
- Conditions: temperature T(H) +85 Celsius, T(L)-55 Celsius; exposure time at 5 minutes; temperature; extremes; number of cycles 3 times
- Results: frequency and wave form of tested products must remain within specification.
- Temperature test, low temperature test:
- Conditions: temperature -20 Celsius +/-2 Celsius; length of test 96 hours
- Results: there should be no stain on surface of products. Frequency and wave form of tested products must remain within specifications.
- Aging test:
- Conditions: temperature +85 Celsius +/-2 Celsius; length of test 96 hours
- Results: deviation of frequency must be less than +/-3ppm (+/-0.0003%)
- Salt spray test
- Conditions: temperature +35 Celsius +/-2 Celsius; length of test 48 hours; NaCl% 5%
- Results: there should be no stain on surface of products
- Humidity test:
- Conditions: temperature +40 Celsius +/-2 Celsius; relative humidity 90~95%; length of test 96 hours
- Results: insulation resistance must be 500 mohm/100 Vdc. Minimum; resistance and wave form must remain within specification.
- Fine leak test:
- Conditions: helium
- Results: less than 2 x 10^-8Atm cc/sec
- Terminal strength, lead pulling test:
- Conditions: load 907.2 gram; direction to the downward; duration of applied 5 seconds force
- Results: there should be no distortion in appearance
- Terminal strength, lead bending test:
- Conditions: load 456.6 gram; bending angle 90 degree to normal position; rate of bending 3 seconds in each cycle
- Results: there should be no distortion in appearance
- Lead solderability test:
- Conditions: dipping in solder (230 Celsius +/-5 Celsius) for t seconds
- Results: more than 95% of surface being tested should be coated uniformly with solder.
- Vibration test:
- Conditions: frequency 20~55Hz; amplitudo 0.762mm; sweep 1.0 minute; duration 2 hours
- Results: frequency and wave form of tested products must remain within specifications
- Drop test:
- Conditions: method of drop, natural drop; dropping floor, hard wood board; height 75cm; number of drops 3 times
- Results: frequency and wave form of tested products must remain within specifications
- Resistance to soldering heat:
- Conditions: going through the reflow furnace with the condition shown in fig A and fig B in series. The specimen shall be stored at room temperature for 1 hour. After that measurement shall be made.
- Results: electrical characteristics shall be satisfied. The changes of frequency must be within +/-5ppm.
Features
- Temperature coefficient:
- Temperature coefficient is frequency stability or deviation with temperature change. Temperature coefficient is expressed in parts per millions, change of plus or minus percentage over the operating temperature ranges.
- The mode of vibration, the plane of the plate in relation to the axis of the quartz, the dimensions of the plate and the harmonic determine the temperature coefficient.
- Spurious modes:
- Spurious modes, which mean unwanted modes, are actually inharmonic modes of vibration of the quartz plate. Since spurious modes are inherent in every crystal resonator, they are suppressed by special design technique.
- Typical spurious specifications are 6db below the desired mode of oscillations but they are more highly suppressed upon customer's request.
- Drive level:
- The drive level normally referenced in milliwatts is the power dissipated in the crystal's equivalent resistance.
- Drive level should be the minimum necessary to begin and maintain crystal oscillation, to assure optimum performance and stability.
- Excessive drive can result in breakage of the crystal element, excessive frequency drift, and pooraging characteristic.
- Aging:
- Aging of a quartz crystal is a general term applied to any change in parameters of a crystal unit taking place over a period of time.
- In order not to suffer severe aging the circuit should be designed with drive level kept at absolute minimum.
Main Products
crystal unit, oscillator, crystal filter