The entire production process operates from Rakon's facilities in New Zealand. Rakon's headquarters are also the base for a skilled R&D and Engineering team. Rakon's unique and innovative manufacturing equipment is recognised as one of the world's best for crystal and oscillator production. The Rakon Crystal Production Process: Cutting Synthetically grown quartz bars are limbered into thin quartz wafers (blanks) using highly accurate multi-blade slurry saws.   The angle of cut has a direct relationship to the frequency versus temperature characteristic. Orientation of the bar is set-up with the assistance of X-ray equipment.

Lapping 'Four way' lapping machines grind the wafer surfaces using abrasives to a targeted thickness while maintaining flatness in a three stage process: first in wafer form, then diced form, and finally, after rounding. With AT-cut quartz blanks, the wafer thickness determines the frequency. An accuracy of 0.1mm or less is required. Note that as the blank gets thinner, the frequency increases.

Dimensioning The Blank The blank dimension is critical to the crystal’s design. Depending on the crystal package the blank is rounded or cut into a rectangular shape. Dimensioning the blank to tight tolerances with a fine surface finish is also important with respect to frequency temperature performance and aging. With lower frequency blanks, the centralisation of vibration requires curved surface processing along the circumference of each blank. Hence lower frequency blanks are beveled.

X-Ray The quartz wafers or blanks are X-rayed to measure the angle with respect to the reference lattice plane in terms of degrees, minutes and seconds. Etching The quartz blanks are etched in an acidic solution to improve the surface finish and reduce the spread in frequency of the production batch.

All processes from etching through to sealing are performed in a class 1000 clean room with class 100 work stations and processes. This type of environment is considered essential for the final stages of production of high performance crystals as particle contamination can contribute greatly to DLD (Drive Level Dependency), poor phase noise, micro-jumps and aging. Process particle laser counters monitor the environment and critical stages and pieces of equipment, and liquid born particles are also monitored and controlled.

Thin Film Deposition A high vacuum thin film deposition machine evaporates a metal onto the surface of each blank to form an electrode pattern. This base plating process is considered to be most critical in achieving well-behaved low aging crystals.

Auto Mounting and Gluing Mounting and gluing is performed by purpose built robots designed to perform their function with low contamination and stress. The quartz blank is mounted on a supporting fixture with a conductive glue making electrical contact to the electrodes on each side of the blank.

Precise Plating The frequency of each quartz crystal is measured while a metal is evaporated onto one side of an exposed electrode until the target frequency is reached to within + 1ppm.
Sealing The inside of a holder is evacuated and filled with the inert Nitrogen gas to protect crystal elements mechanically and prevent electrodes or other parts from being oxidised or influenced by ambient temperatures. Sealing methods of resistance or seam welds are used depending on the package. Sensors monitor the process environment. The crystals are then fine and gross leak tested before parameter testing and aging.

Initial Crystal Test, Aging and Final Crystal Test The crystals are tested for their motional parameters and sorted into frequency groups. After aging at an elevated temperature for a period of time the motional parameters are tested again ensuring the parameters are maintained to the required process specifications. This is an essential SPC (Statistical Process Control) point to highlight any process problems.

Temperature Test The crystals are 100% tested in the temperature chambers for frequency characteristics over the intended temperature range. [applies to Crystal production]

PCB Assembly, Crystal Matching and TCXO Assembly The PCB panels go through Solder Paste Screening, Component Pick and Place and IR-reflow Production Line. Crystals are matched to assembled PCB’s. This also allows for a narrow trimming range making it easier to tune the oscillators on frequency. [applies to Oscillator production]

Final QC And Packaging Any leg-forming, jacketing and marking of the crystals is inspected. The crystals are then packed and released by our Q.C. department. [applies to Crystal production]

Temperature Test, Compensation and Oscillator Aging The Oscillators are 100% tested in the temperature chambers for frequency characteristics over the intended temperature range. If an oscillator does not pass the specification, component values are changed to compensate the unit. The unit is re-tested in the temperature chamber before it is passed. The completed oscillators are aged at an elevated temperature for a period of time and tested for any abnormal frequency shifts. [applies to Oscillator production]

Final Test and Packaging The trimming range of the oscillators is tested, as is the short term stability and frequency shift due to shock. The oscillators must pass a final inspection and is then checked and released by our Q.C. department. [applies to Oscillator production]

 

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