COTS, New Space, LEO Constellations

COTS quartz crystal units – up-screening for space applications

  • Posted by Bernd Neubig
  • On December 3, 2019
  • 0

Content

  • Introduction AXTAL – Advanced Crystal Products

 

  • Requirements for Quartz Crystals in Space

 

 

  • Quartz Crystals compliant to ECSS3501

 

      •   Scope of ESCC3501
      •   Tests
      •   ESCC3501 Qualified Quartz Crystals and Manufacturers
      •   ESCC3501 Crystals from Non-ESA Qualified Manufacturers
      •   Sourcing Options

 

  • Up-Screening of Precision Crystals
  • COTS Quartz Crystal Units
  • Up-Screening of COTS Crystals (Space-COTS Crystals, SCC)

 

 

  • AXTAL GmbH&Co.KG
    • Wholly privately owned company, founded in November 2003 by Bernd and Brigitte Neubig
    • Bernd Neubig: More than 40 years technical experience in the Quartz Industry
    • Development, Prototyping, Testing, and Manufacturing of Frequency Control Products, namely High Performance Crystal and SAW Oscillators and Ultra Low Noise Frequency Control Modules
    • Design & Manufacturing of Oscillators for Space since 2011.
    • Listed on ESA EPPL since 2014 (OCXO AXIOM6060 series)
  • Main markets:
    • Space and Aerospace
    • Navigation, Surveillance
    • Satellite Communication
    • Military (Ground, Mobile, Marine, Aerospace)
    • High Precision RF Test Equipment
  • Facility location: Mosbach/Baden in South West Germany
    • Complete manufacturing line, extensive  test equipment, Quality Management, R&D
    • Quartz crystals sourced from selected manufacturers, ITAR free

 

Requirements for Crystals in Space

 

  •  … Strongly depending on the application

 

      •  Mission: LEO, MEO, GEO, Interplanetary, Deep Space 
      •  Reliability Level: Cubesats, Scientific, New Space, Navigation, Telecom
      •  Mission Time

 

  •  … Strongly depending on the needed technical parameters 

 

    •  Frequency Accuracy 
    •  Frequency Stability over Time (Aging)
    •  Frequency Stability vs. Environmental Conditions
      • Mechanical (Shock, Vibration)
      • Radiation (TID, SEE)
    •  Spectral Purity, Noise 

 

  • Extremes for Accuracy and Stability
    •  Precision Crystals
      • Frequency stability in the ppb-range (10-9) or better
      • Frequently combined with demanding spectral purity and Low Noise
    • Clock Crystals 

 

 

      • If not time-critical:  stability typically ±50 ppm … ± 100 ppm or more 
      • If connected with „coarse“ timing:  n·1 ppm
        1 ppm = 31.5 sec /year

 

    •  And many applications in between …

 

  • Stability requirements drive Cost (Price) and Availability (Lead time)

 

 

 

Requirements for Quartz Material

 

  •  Radiation effects:

 

      • Spontaneous small frequency changes
        un-swept „conventional“ quartz material: 10-11/rad, swept quartz ca. 10-12 …10-14/rad
      • Slight reduction of Q-factor = slight increase of resonance resistance (low %)
    • Traditional approach (Precision Crystals): Swept Quartz material

quartz material

    • Modern Crystal Growth Technologies
      • Ultra-low etch-channel  density (ECD), and low inclusions 
      • Performance close to Swept Quartz possible
      • Significantly lower material cost, shorter lead time
    •  Majority of applications (µP clocks etc.) does not need the highest level of frequency stability -> non-swept quartz

 

Quartz crystal units in ESCC3501

  • Scope

scope

 

    • Procedures for the ESA qualification of quartz crystal units 
    • Procedures for qualification of crystal manufacturers
    • Basis for the procurement and delivery of crystals from ESA-qualified manufacturers

 

  •   Qualification approval of quartz crystals

qualification

 

  •  Procurment of quartz crystals

 

Procurment

 

 

Final Production Test (Chart II)

final test

Burn-In & Electrical Measurement (Chart III)

burn-in

Lot Acceptance Test (Chart V) – optional

Acceptance

 

  •  ESCC3501 Qualified quartz crystals and manufacturers

 

    • Detail Specifications ESCC3501/xxx
      • /001 to /012 obsolete, active …/013, /018, /019, /020, and Blank Detail Specification
    •  Package styles
      • THD: HC-35/U, HC-37/U, HC-40/U, (HC-27/U),    SMD: 7 x 5 mm²/4-Pad
    • Only one qualified Manufacturer in Europe
      • Qualified for two package styles (HC-35/U, HC-37/U) only

manufactures

 

 

  •  Pros

 

      • User knows what he is going to get
      • Proven quality from proven manufacturer
      • Profound technical specification system

 

  •  Cons

 

    • Very limited number of package styles (no modern SMD packages)
    • Expensive
    • Long lead time
    • Insufficient flexibility for customer/application specific products
    • Not appropriate for Space COTS requirements

 

  •  …What percentage of crystals in space are really ESCC3501 parts?

Alternative 1: ESCC3501 components from AXTAL

 

  •  ESCC3501 compliant crystals from non-ESA-qualified manufacturer

 

    • Supplier should have heritage with products used space
    • No potentail or real risk with export / import regulations (ITAR or EAR)
    • AXTAL:
      • Long lsting close cooperation with CROVEN CRYSTALS in Canada
      • CROVEN supplies the crystals used in the EPPL listed AXTAL OCXO AXIOM6060
      • AXTAL is European agent for CROVEN high precision crystals since 2017
    • CROVEN CRYSTALS:
      • Founded 1954, since 2006 wholly owned by Wenzel Associates
      • Leader in the design of precision qaurtz crystals
      • Long Space heritage (Mars -Observer, -Pathfinder, -Climate Orbiter, -Polar Lander…)
      • Canada is ESA member country
      • No ITAR issues
      • Audited and Pre-cap inspections yb AXTAL since 2017

 

  •  Procurement Options

 

    • Shipment through AXTAL with CROVEN document package
      • Optionally with LAT
      • Document package content TBD
         
    • Optional: Precap Inspection to ESCC2043501 or Factory Audit
      • By customer QM, accompanied by AXTAL QM expert
      • By AXTAL QM expert
    • Optional: Additional Tests, Burn-In or LAT performed by AXTAL
      • In accordance with ESCC3501 or Customer Specific
      • Radiographic Inspection IAW ESCC2093501 (external lab)
      • Total Dose Test IAW ESCC22900 (external lab)

 

alternative2Alternative 2: Up-Screening of Precision Crystals

 

  •  Procurement of CROVEN crystals through AXTAL

 

      • Other manufacturers on request

 

  •  Non ESCC-3501 packages available
  •  small and SMD packages
  •  Burn-In Test to ESCC3501

 

    •  Level B or Level C
    •  Lot Acceptance Test to ESCC3501

 

  •  Level 1, Level 2 and/or Level 3
  •  Evaluation Test IAW ESCC2263501
  •  … performed by AXTAL Labs

 

    •  Most tests are in-house, complete document package

 

Alternative 3: „Space-COTS“ Quartz Crystals

 

  •  Guidance in the Selection of suitable COTS Manufacturer

 

    •  More than 40 years experience and knowledge of the crystal market
    •  Use of recognized manufacturers
      • with Automotive approval, or 
      • with proven experience in MIL applications
      • with established Statistical Process Control (SPC) and Traceability System
    •  No use of Distributors or „Pseudo manufacturers“!

 

  •  Up-screening by AXTAL according to MIL-PRF-3098

 

      •  Level S or Level B

 

  •  Up-screening by AXTAL to slim-lined MIL-PRF-3098

 

    •  Level „X“

 

Up-Screening of COTS crystals: „Space-COTS“

screening ml

 

CONCLUSIONS

 

  •   ESCC3501 is a good guidance for crystals used in space
  •   For applications with challenges for low cost and short lead time ESC3501/xxx crystals are not appropriate
  •   Alternatives for COTS applications are
    • Use of precision crystals screened to ESCC3501 or MIL-PRF-3098 Level S
    • Up-Screening of COTS crystals with higher performance (e.g. Automotive grade)

 

      • MIL-PRF-3098 Screening Level S or B
      • Slim-lined MIL-PRF Screening “Level “X”
Bernd Neubig
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