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Environmental Conditions for Frequency Components
Excessive drive will cause premature aging at least and failure of the vibrating element at worst. The user should verify that drive levels in the circuit are well within the limit specified for the part.
Crystal leads protrude from the can via a hermetic glass seal and bending the lead within 0.5mm of the case is likely to cause deterioration of the air tight seal and crystal characteristics. Also flexing of a printed circuit board may over stress a can or ceramic package. The crystal should be laid out in the plane of least stress.
A different oscillation frequency from that expected in a crystal or resonator based design is a symptom of an incorrect value of load capacitance. Poor matching of load to piezoelectric device may create an error in excess of 200ppm. Please refer to ACT design examples or ask for our Technical Support.
A different oscillation frequency from that expected in a crystal or resonator based design is a symptom of an incorrect value of load capacitance. Poor matching of load to piezoelectric device may create an error in excess of 200ppm. Please refer to ACT design examples or ask for our Technical Support.
Sounders, buzzers or loudspeakers near a crystal product can change its output frequency or amplitude. We suggest that they be mounted on a board which is separate from the crystal or resonator.
Devices able to withstand infra red reflow or vapour phase soldering will survive 230ºC for 10 seconds. Parts for wave soldering will survive 230ºC for 5 seconds, provided the solder does not get within 2mm of the body. Excessive or prolonged heating will permanently change the frequency or cause the internal mounts to fail. In any case the package temperature should not exceed 150ºC.
The limit is 3 drops from 75cm on to a hard wooden board. Careless handling of low frequency crystals may cause a total failure of the parts if the piezoelectric element separates from its mounting springs. This element in high frequency crystals may shatter. Another symptom is excessive noise or incorrect frequency if the part has been unduly but not fatally stressed. Automatic mounting can introduce extreme shocks, so the set-up should be adjusted to minimise sudden accelerations or decelerations.
Excessive levels of static electricity will damage the integrated circuits within oscillators. Pack parts in an anti-static material, a dissipating bag or box. Always solder and test in an electrostatic safe environment.
Storage at an ambient above 25ºC will accelerate the aging of a crystal or resonator. Storing in high humidity will accelerate oxidation of the tinned leads and adversely influence solder ability. Parts should be mounted as soon as possible after unpacking.
Watch crystals and resonators should not be ultrasonic cleaned at 40KHz and high sound intensity. The usual intensities at 20kHz should be safe but the user is advised to verify satisfactory operation of a statistically acceptable sample after a cleaning cycle.
Parts in a full welded can are adequately sealed. Plastic and ceramic encapsulated devices may give off vapour from markings. Ceramic resonators have their piezoelectric element sealed in inert gas, and placing them in a vacuum is likely to make this fail.
Devices that are hermetically sealed may be washed. Parts with vent or trim holes and Ceramic resonators should not be washed. Epoxy dipped parts may be washed. Plastic encapsulated parts may be sensitive to the mixture of contaminants and water after reflow soldering. This may give rise to a temporary short circuit, which will disappear when the parts have dried. It is the responsibility of the customer to determine the effects of their cleaning process on ACT products.
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email : info@actcrystals.com
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