Different options for Panel C Mounted EMI Filters

It is common knowledge that leads time is often a critical aspect of Procurement of EEE parts for Space Applications. Some specific family types usually suffer from having long lead times (more than one year on some occasions), which makes them a major driver on any procurement. One of the most affected families are Space Qualified Panel C Mounted EMI filters.

Four alternatives are considered for Space applications on this note:

• SFC035 Series manufactured by Exxelia: these parts are QPL following ESCC 3008/031 and do not generally require any additional testing to meet Class 1 requirements.  However, according to the last ESCC QPL, the following must be considered:
  • All Variants are qualified except SFC filters rated 200V, whose qualification status is suspended from 25-May-2018. The shipment of ESCC Qualified filters rated 100V, in sizes 030, 035 (3008/031) and 040 is conditional to the satisfactory implementation of Endurance testing (as required in ESCC 3008) on the actual filter batch.

The range of components available from this specification is as follows:

• Filters Panel Mounted C – Filter Panel Mounted C manufactured by Oxley: these parts are not qualified and therefore should be subjected to screening and lot validation testing (LVT) before use on Space applications. These parts are available in two series: DCT (capacitor filter) and DLT (LC style filter by the inclusion of inductance within the threaded area). In relation to DC voltage, the parts are available in 100V, -55ºC to +85ºC (87V, +125ºC) or 200V, -55ºC to +85ºC (175V, +125ºC). Part finish is available on Pure Tin (not suitable for space applications) or Silver, while wire availability comprises plain wires or headed wires. Regarding capacitance, following options are available: 22pF, 100pF, 2700pF and 47000pF.

• Resin Sealed Bolt-in Filters manufactured by Spectrum Control / API Technologies: These components are qualified per MIL-F-15733 (not all of the series). Main features are:
  • Wide range of sizes: 4-40 thread through5/16-24 thread
  • Voltage ratings to 500 VDC/220 VAC (400 Hz)
  • MIL-F-15733 QPL filters available
  • Multiple circuit configurations: C, L and Pi
  • Metric threaded filters available, consult factory

Even if these parts are QPL, they are only subjected to Group A in accordance with specification. Thus, Screening on the parts as well as Group C should be performed as part of the procurement procedure.

Moreover, Spectrum Control also manufactures parts qualified per MIL-PRF-28861 “FILTERS AND CAPACITORS, RADIO FREQUENCY/ELECTROMAGNETIC INTERFERENCE SUPPRESSION, GENERAL SPECIFICATION FOR”. In this case, Spectrum Control only manufactures these filters on Class B quality level. Therefore, Group B testing should be performed on the lot as part as the procurement procedure.

• EMI filters qualified in accordance with MIL-PRF-28861 manufactured by AVX: AVX manufactures EMI filters qualified per MIL-PRF-28861; in particular, parts under detail specification MIL-PRF-28861/01, MIL-PRF-28861/04, MIL-PRF-28861/05 & MIL-PRF-28861/12. Qualified products are only available on Class B quality level, which includes Group A testing. Therefore, Group B testing should be performed as part of the procurement procedure. Also, Class S including Group A and Group B can be ordered from AVX, although parts are not qualified in this case.

As a summary, options available can be condensed as follows:

These provide a wide field of different cost/lead time options that offers the users the opportunity to take the best alternative according to their needs.