Brookdale Frequency Control, Inc. - World Class Supplier of TCXOs, VCXOs, Oscillators and other Frequency Control Products

Frequently Asked Questions and Answers

What precautions should I take when handling an oscillator?

How are Crystals Blanks and Crystral Oscillators produced?

What are the mechanical and environmental specifications of oscillators?

        Drop:
                   Because of the fragile nature of the crystal blank, extreme care should be observed when handling
                   oscillator. If the oscillator is inadvertently dropped to floor, please do the measurements again.

                   There are several failure modes, which result from dropping units, including broken crystals, broken
                   interconnects, damaged package and broken glass seals.

       Static Electricity:
                  Although an anti-static-electricity protection circuit is provided in the oscillator, excessive levels of
                  static electricity may damage the IC.

                  Please use the oscillator in environments duly provided with anti-static measures, free from high
                  voltage leak with ground connection.

       Mounting:
                  Mounting of the oscillator incorrectly may cause malfunction and breakdown. So please check the
                  mounting diretion when installing.

       Others:
                  a.     Oscillators should be stored in a dry environment.

                  b.     Finger cots should be worn whenever oscillators are to be handled.

                  c.     If crystals are subjected to extreme temperature outside storage temperature limits, the
                         electrical performance can be affected, resulting in eventual failure.

                  d.     Since a crystal blank can be broken by resonance when a oscillator is cleaned by ultrasonic
                          cleaning. Be careful when cleaning.

Back to the top of the page

Crystal Blank

        Cutting and Measuring cutting angle:
                 A synthetically grown quartz bar is lumbered into thin quartz wafers according to the
                 specified cutting angle, which has direct relationship to the frequency vs. temperature
                 characteristic.

        Dimensioning the blank:
                 Depending on the oscillator package, the blank is rounded or cut into rectangular
                 shape.

        Lapping:
                 Lapping machine grind the wafer surfaces using abrasives while maintaining flatness.
                 The thinner the blank, the higher the frequency.

        Beveling:
                 To cause vibrations to occur at the center, the crystal piece is shaped into the form of
                 lens.

        Etching and Cleaning:
                 The quartz blanks are etched in a solution to improve the surfaces finish and reduce
                 the spread in frequency of the production batch.

Crystal Oscillator

        Base Plating:
                 The electrode, used for applying an electric field to the crystal blank, is formed by
                 vacuum metal deposition using silver on the top of the crystal blank.

        Mounting crystal blank into substrate:
                 The crystal blank is mounted on supporting springs with silver paste making electrical
                 contact to the electrodes on each side of the blank.

        Precise Plating:
                 The frequency of each oscillator is measured while silver is evaporated onto one side
                 of an exposed electrode until the target frequency is reached.

        Sealing by Resistance Welding:
                 The inside of a oscillator is evacuated and filled with the inert Nitrogen gas to prevent
                 electrodes from being oxidized or influenced by ambient temperature.

        Aging and Electrical test:
                 After aging at an elevated temperature for a period of time, the electrical
                 specifications are tested.

Back to the top of the page

Test Item	Test Condition	Test Result
Shock Resistance (Drop)	Natural drop on a hard wood board from a height of 75cm, three times	Frequency and waveform of tested products must remain within specifications.
Vibration	Vibration with amplitude of 0.762mm and sweep time of 1 minute at 10 to 55Hz for 2 hours on x,y and z axis	Frequency and waveform of tested products must remain within specifications.
Lead Strength	Lead Pull : 0.9 kg downward for 3 sec. Lead Bend : Maximum bend of 90° reference to base for 2 bends	There should be no distortion in appearance.
Solderability	Dipping in solder(230° ±5°C) for 5 sec.	95% of the cooled solder surface is uniform and free from breaks and pinholes.
Resistance to Solder Heat	Dipping in solder(260° ±5°C) for 10 sec.	Frequency and waveform of tested products must remain within specifications.
Temperature Cycle	Thermal shock of 3 cycles of dwell in baths of -55°C for 30min., +25°C for 15min., +85°C for 30min., +25°C for 15min.	Frequency and waveform of tested products must remain within specifications.
Moisture Resistance	Exposure to temperature of +40°C and humidity of 90% RH for 96 hours	Frequency and waveform of tested products must remain within specifications with no significant rusting.
Aging	30 days @ 85° C or 7 days @ 105°C	Deviation of frequency must be less than ±5ppm or custom specification.
Hermetical Seal	Fine Leak: Measurement with mass spectrometer Gross Leak: Test in de-ionized H₂O	Leak rate less than 2x10^-8 Atmos CC/sec. of Helium. Air bubble would not be found in de-ionized H₂O.

Back to the top of the page

TTL, TTL / HCMOS Test Circuit	(Sine Wave Test Circuit) TCXO, VCTCXO


HCMOS Test circuit	Dual HCMOS Test Circuit


Pecl Test Circuit Diagram


Pecl Output Waveform

Back to the top of the page