ESD_08_ESDProtectionOnCubesSatsUsingCOTSComponents

Failures in CubeSat missions can have a number of root factors.  One of the most important failure causes is whether ESD handling protocols were in place during development or not.  Several studies have been conducted in this regard [5][6][7][8] with important results coming from the research of Amin Djamshidpour, co-founder of Teton Aerospace [13]. In the summer 2016 issue of the “Consortium Connection” magazine [11], a valuable article titled "CubeSat Protocols for Launch Integrity" written by Bob Vermillion from RMV Technology Group in Moffett Field, CA [12] points out some important aspects to consider.

 

One of the points that the article makes is that even with the lower cost for CubeSat satellites and COTS components compared with traditional satellite building, the requirements for ESD handling protocols must be the same.  If not, the operational integrity of the CubeSat will be in doubt.

 

Mark Betancourt, Air & Space Smithsonian, January 2016,

 

“...CubeSat launches have remained steady—118 in 2014, 108 last year—their success rates are still comparatively dismal. One out of every three CubeSats that reach orbit fails to accomplish its mission (one in four is lost in a launch failure)...”

 

According to the article, some CubeSat manufacturers have reported up to 50% operational loss in space. High transistor density per chips in modern electronics requires special handling that must include ESD handling procedures.  However, the author [12] found that when CubeSat designs include ESD sensitive components they often lack proper ESD handling procedures. JPL, along with many other organizations and universities, are taking these issues into account by preparing or adapting special areas or reusing previous program areas to now work with CubeSat components. However, this is not always the case and ESD handling procedures are often overlooked.

 

In the article, the research of the author, Bob Vermillion [12], reminds us of important considerations about CubeSat construction that are key for everyone involved in CubeSat development:

 

  • "CubeSat construction has been observed on charge generating Plexiglas or Lexan platforms that could facilitate field induced model (FIM) discharges. The incorporation of an ANSI/ESD S4.1 approved work surface is required to safeguard today’s circuit cards from Class 0A devices (<125 volts) to Class 1A (250 to <500 volts) for ESD sensitive devices" [11].

  • "Adherence to static control protocols in compliance with ANSI/ESD S20.20-2014 requirements is not optional when building CubeSats. ANSI/ESD S20.20 applies during test, inspection, transport and handling of electronic parts, assemblies and equipment susceptible to ESD damage greater than or equal to 100 volts HBM, 200 volts CDM, and 35 volts on isolated conductors [7]. The Department of Defense and NASA have adopted ANSI/ESD S20.20 along with the prime contracting community" [11].

  • "The argument that S20.20 does not apply to devices rated above 125 volts (Class 0A devices) is unfounded. To dispel one myth, some COTS are Class 0A; the same classification can also apply to ESD sensitive EEE parts for GOTS from DOD authorized distributors" [11].

  • "This subject alone will require a separate white paper. To be in conformance with ANSI/ESD S20.20-2014 when tailoring outside the limits, one must have technical justification in order to downgrade practices or waiver requirements" [11].

  • "Product qualification of ESD materials must conform to ANSI/ESD S20.20-2014 using traceable technical data, in-house testing or by an independent lab using instrumentation as called out in the ANSI/ESD Standards or Standard Test Methods. For in-house qualification, the on-site qualifier must conduct testing of ESD materials at the stated relative humidity (RH) and temperature levels. If the RH and temperature levels are not achievable, then said evaluator must qualify ESD materials at worst case conditions that could be experienced in a 12-month period, for example, the Santa Ana Wind conditions at Edwards Air Force Base" [11].

  • "For Aerospace & defense, it is not uncommon to build and assemble products in Class 1A (250 to <500 volts) ESD protected areas (EPA). Other organizations will designate micro-EPAs to Class 0A or 0B compliance" [11].

 

The article also points out the requirements of the ESD workstation area in terms of certification and calibration. In previous sections of this tutorial we presented different components of an ESD workstation.  Here, we focus on the ANSI/ESD S4.1 as the calibration that certifies the correct operation of the work area. The article contains a figure (Figure 1) from the RMV Laboratory at NASA Ames Research Park [12] that we reproduce here to show some key points:

 

  • "ANSI/ESD S4.1 work station is certified (calibrated) annually with periodic verification taking place as outlined in an organization’s ESD Procedures" [11].

  • "Calibration label is affixed to the work surface, ionizers, flooring mat, static control chair, soldering iron, wrist strap monitor and proximity voltage sensing antennas" [11].

  • "Hard data is recorded - not simply stating pass or fail" [11].

 

 

ESD protection general

 

Figure 1: RMV Laboratory at NASA Ames Research Park [12]

 

    Finally, the article [12] reminds us of some important mitigation techniques that both manufacturers and CubeSat team participants must adopt when handling Class 0A components:

     

    1. Maintain relative humidity (RH) greater than 40%RH with temperature and RH monitored in the Electrostatic Protected Area  (EPA) [8]
    2. Use groundable ESD garments (overalls) with elastic wrist cuffs
    3. Use Steady State DC Ionization with an offset voltage of <+/-35 volts
    4. Use a dual cord audio jack wrist strap when seated
    5. ESD Chairs
    6. Qualify all ESD Protective Packaging before utilization on an ESD work surface
    7. Remove all non-process insulators from the work area

     

    Special thanks to Bob Vermillion, CPP, Fellow Certified, ESD & Product Safety Engineer-iNARTE A NASA Industry Partner, RMV Technology Group, LLC [12]

    As also to Amin Djamshidpour, Co-Founder Teton Aerospace, amin@tetonsys.com [13].

    and to ConsortiumConnection Magazine. http://ad9867.wix.com/clhtc#!news. 2016. Summer Edition [11].