Crystals & Crystal Oscillators

Gerard F. Kiernan, QSS Group Inc, CODE 562, NASA/GSFC

Discrete crystals for space flight use are procured using MIL-PRF-3098 as the basis for the procurement. Crystal Oscillators for space flight use are procured with requirements based on MIL-PRF-55310. MIL-PRF-55310 offers a "space level" class S part, but only one manufacturer is listed on the Qualified Products List as supplying to class S and that is for MIL-PRF-55310/16. This detail specification has no radiation requirement.

Both crystals and oscillators need to be procured using a Specification Control Drawing, if radiation hardness is a concern for the mission.  MIL-PRF-3098 does not address the question of radiation hardness of crystals, at all.  MIL-PRF-55310 includes test procedures for various radiation environments and, requires lot testing of semiconductor and microcircuit dice, for radiation effects as part of element evaluation.  The specification does not require testing of the crystal itself.

Major Issues

For space flight use of crystals or crystal oscillators, crystals shall be swept synthetic quartz, meeting the infrared quality requirements of grade A or B of Synthetic Quartz Crystal Specifications and Guide to the Use, IEC60758 (1993-04), International Electrotechnical Commision, Geneva, Switzerland.  Crystals shall be mounted with at least a three-point mount.  

For crystal oscillators, all semiconductor devices must be rad-hard, not just rad-tolerant.  No parts shall be used that latch up in a Single Event Upset (SEU) environment.  All active and passive parts shall be derated in accordance with the quidelines of MIL-STD-975.

For tuning fork types of crystals, refer to DSCC (Defense Supply Center-Columbus) Drawing 94023 for a model on which to base your SCD.

Upcoming Events

• EIA G11 Component Parts Committee, several meetings per year
• EIA/ECA P11 Committee on Quartz Crystals, several meetings per year
• EIA Piezoelectric Devices Association, meeting schedule to be determined
• 2005 IEEE International Frequency Control Symposium jointly with PTTI Applications & meeting Planning, August 28-31, 2005, Vancouver, BC, Canada
• NASA/DoD Space Parts Working Group, annual meeting in late April/early May

Status of New Sources of Information

EEE-INST-002 has been issued.  It can be downloaded from the NEPP web site.  The new replacement for 311-INST-001 has sections on both crystals and crystal oscillators.

Documents and References

• EEE-INST-002 Instruction for EEE Parts, Selection, Screening, Qualification, and Derating, Crystal and Oscillator Sections
• MIL-PRF-3098 Crystal Units, Quartz, General Specification for
• MIL-PRF-55310 Oscillator, Crystal Controlled, General Specification for
• National Institute of Standards and Technology (NIST) Technical Note 1337-Characterization of Clocks and Oscillators.  This Tech Note is referenced in MIL-PRF-55310.  It is no longer available from the U.S. Government Printing Office, but is available at the NIST Boulder, Colorado web-site: www.boulder.nist.gov/timefreq.  Look under the publications section.
• The IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society has much useful information available on its web site.  It is available at www.ieee-uffc.org, then use the link to frequency control, and then to references and tutorials.
• For EIA meeting schedules, go to the EIA web site at www.ec-central.org. for the P-11 committee.  For the G-11 committee, go to www.geia.org.

Check manufacturer's web sites for applications and technical information.  Many have sections of tutorial and reference information.