A confidence level based approach to total dose radiation hardness assurance is presented for spacecraft electronics. It is applicable to both ionizing and displacement damage dose. Results are compared to the traditional approach that uses radiation design margin and advantages of the new approach are discussed

Campola, M. J.

Label, K. A.

Ladbury, R. L.

McClure, S. S.

Pellish, J. A.

Phan, A.

Stauffer, C.

Xapsos, M. A.

NASA Technical Reports Server

CONFIDENCE LEVEL BASED APPROACH
TO TOTAL DOSE SPECIFICATION
FOR SPACECRAFT ELECTRONICS
M.A. Xapsos1, C. Stauffer2, A. Phan2, S.S. McClure3,
R.L. Ladbury1, J.A. Pellish1, M.J. Campola1 and K.A. LaBel1
1NASA Goddard Space Flight Center, Greenbelt, MD
2AS&D, Inc., Greenbelt, MD
3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
Supported by the NASA Living With a Star Space Environment Testbed Program
1To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
https://ntrs.nasa.gov/search.jsp?R=20170005803 2019-08-31T07:00:16+00:00Z
Outline
• Background
• Device Failure Distributions in Total Dose
• Total Dose Distributions in Space
• Device Failure Probability during a Mission
• Conclusions
 Failure Probability (Pfail) vs. Radiation Design Margin (RDM)
2
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Space Environment Model Use in
Spacecraft Life Cycle
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Radiation Hardness Assurance Overview
• Starting with mission 
requirements, methodology 
consists of 2 branches of 
analyses that lead to parts 
categorization
 Parts analysis
 Environment analysis
4
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017
Radiation Hardness Assurance Overview
• Parts are categorized for flight acceptability and possible radiation lot acceptance testing by Radiation 
Design Margin (RDM).
• RDM = Rmf / Rspec
• Rmf is mean failure level of part
• Rspec is total dose level of space environment
• Difficulties can arise because
 Part failure levels can vary substantially from the mean, especially COTS
 Environment is dynamic and must be predicted years in advance
• RDM based approach results from use of deterministic AP8/AE8 trapped particle models
• RDM used as a “catch-all” to cover all uncertainties in environment and device variations
• Propose modified approach
 Use device failure probability during a mission instead of RDM
5To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Devices Tested
• Solid State Devices, Inc. 
SFT2907A bipolar transistors
 Used for high speed, low power 
applications
 10 devices TID tested for MMS 
project at NASA/GSFC gamma ray 
facility to 100 krad(Si)
• Amptek, Inc. HV801 optocouplers
 GaAlAs parts manufactured in liquid 
phase epitaxially grown process
 6 devices DDD tested for JUNO 
project at UC Davis Cyclotron with 50 
MeV protons
6
4 stacked MMS spacecraft
Credit: http://mms.gsfc.nasa.gov
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Device Failure Distribution
SFT2907A Bipolar Transistors
7
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
• TID and DDD probability distributions were calculated for each orbit 
and mission duration for confidence levels ranging from 1 to 99%
 AP9/AE9 Monte Carlo code used to simulate 99 histories for each case
 ESP solar proton calculations done for 1 to 99% confidence levels
 All energy spectra were transported through shielding levels from 10 to 1000 
mils Al using NOVICE code and converted to doses
 TID and DDD for each radiation were separately ranked for confidence levels 
ranging from 1 to 99% and summed for same confidence and shielding levels
8
Total Dose Probability Distribution Calculations
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
TID Probability Distributions for 1 Year
10 – 1000 mils Aluminum
Low Inclination LEO GEO
9
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Failure Probabilities
SFT2907A Bipolar Transistor
Pfail = ʃ [1 – H(x)] ∙ g(x)dx
H(x) = CDF for environment dose
g(x) = PDF for device failure
Failure probability (Pfail) is the 
probability of a total dose failure 
during a mission
10
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
11
Confidence Level vs. RDM for 10 years in GEO
200 mils Al shield
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Conclusions
• An approach to total dose radiation hardness assurance was developed that includes 
variability of the space radiation environment.
• Examples showed radiation environment variability is at least as significant as 
variability of total dose failures in devices measured in the laboratory.
 New approach is more complete
 Uses consistent evaluation of each radiation in the space environment through use of 
confidence levels
• Advantages of using Pfail instead of RDM are:
 Pfail is an objectively determined parameter because complete probability distributions are 
used to calculate it; gives designers more trade space
 Better characterization of device radiation performance
 Allows direct comparison of the total dose threats for different devices and missions, 
regardless of whether degradation is due to TID or DDD
 More amenable to circuit, system and spacecraft reliability analysis
12
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Acronyms
• AE9 – Aerospace electron model-9
• AP9 – Aerospace proton model-9
• CDF – cumulative distribution function
• COTS - commercial off the shelf
• DDD – displacement damage dose
• ESP – Emission of Solar Protons (model)
• FP – failure probability
• GEO – geostationary Earth orbit
• HST – Hubble Space Telescope
• JUNO – JUpiter Near-polar Orbiter
• LEO – low Earth orbit
• MMS – Magnetospheric MultiScale
• NOVICE – Numerical Optimizations, 
Visualizations and Integrations on Computer 
Aided Design (CAD)/Constructive Solid 
Geometry (CSG) Edifices
• PDF – probability density function
• RDM – radiation design margin
• TID – total ionizing dose
13To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
BACKUP SLIDES
To be presented by Mike Xapsos at the 2016 Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Space Radiation Effects Conference (NSREC), Portland, Oregon, July 11-15, 2016. 14
Device Failure Distribution
HV801 Optocoupler
15
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
DDD Probability Distributions for 1 Year
10 – 1000 mils Aluminum
Low Inclination LEO GEO
16
To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.
Failure Probabilities
HV801 Optocoupler
Pfail = ʃ [1 – H(x)] ∙ g(x)dx
H(x) = CDF for environment dose
g(x) = PDF for device failure
Failure probability (Pfail) is the 
probability of a total dose failure 
during a mission
17To be presented by Mike Xapsos at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA/GSFC, Greenbelt, MD, June 26-29, 2017.


Confidence Level Based Approach to Total Dose Specification for Spacecraft Electronics

Confidence Level Based Approach to Total Dose Specification for Spacecraft Electronics

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