Overview

1
THE NASA EEE PARTS ASSURANCE GROUP
(NEPAG) Presentation to the Space Parts Working
Group Torrance, California, May 1, 2001
Michael J. Sampson, Code 306, NASA Goddard Space
Flight Center, Greenbelt, Maryland 20771 Phone
301-286-3335 Fax [phone] msampson_at_pop300.gs
fc.nasa.gov
2
Overview
NASA EEE Parts Assurance Group (NEPAG)

• Origins
• Changing World of EEE Parts
• A New Start
• Study
• Charter
• Objectives
• Organization
• NEPAG/NEPP
• FY01 Activities
• Issues and Concerns
• FY02 Plan
• Conclusions

3
Origins

• NASA Parts Project Office
• Mid 80s to 95
• Agency-wide standard part program - MIL-STD-975
• Project Office at Goddard Space Flight Center
  (GSFC)
• Began EEE Parts Information System (EPIMS) parts
  database
• EEE Parts/Advanced Interconnect/ Radiation
  (EEE/AI/RAD) Program
• 96 to 98
• MIL-STD-975 replaced with the NASA Parts
  Selection List (NPSL)
• Emphasis on newer technologies
• Responsibility shared between GSFC and Jet
  Propulsion Laboratory (JPL)
• NASA EEE Parts and Packaging (NEPP) Program
• 98 to Present
• New and Emerging Technology Evaluation
• Program office at JPL
• NPSL still maintained but de-emphasized
• No Agency coverage of mature, familiar
  technology

4
The Changing World of EEE Parts Assurance

• Acquisition reform
• Insight versus oversight
• Rush to use COTS
• Apparent belief that all parts assurance problems
  would be solved by using COTS
• The MIL system is dead
• Rapid technology change
• Dynamic supply chain (who owns who this week?)
• Downsizing - NASA has lost most of it specialists
  and about half of its total parts engineering
  resource

5
A New Start

• Late 1999, PE leads at NASA centers organize
  informal parts engineering forum
• Regular telcons to share experiences
• Establish simple, functional website
• Early 2000, NASA HQ, Code Q organizes studies of
  NASA-wide EEE parts assurance needs for effective
  risk management
• Late 2000, NASA EEE parts assurance group formed
• Goddard Space Flight Center is lead Center
• PE Leads at 5 NASA Centers and JPL
• Co-funded by NASA HQ Codes Q and AE
• Later expands to include USAF, NAVSEA Crane,
  European and Japanese National Space Agencies

6
The Study

• Telcons and Face-to-Face Meetings with Center
  Representatives - Focus Groups
• Agency-wide Survey - current capabilities and
  needs
• Risk Analysis Using Risk Matrices
• Fishbone Diagram Constructed
• High Risk Commodities Identified
• Survey Performed to Identify Critical Needs

7
Critical EEE Parts Processes Identified by
Analysis

• Preferred Parts Program - Parts Source
  Selection
• Reliability Validation Program Risk Assessment
• Procurement Management Program Project Level
  Services
• Failure Resolutions Lessons Learned
• Maintenance of Core Competency
• Forecasting EEE Parts Needs
• 37 Major Subprocesses were identified for these 6
  Primary Processes
• Processes which most enable risk management

8
Ratings Results
In the recent past, NASA has emphasized the
Procurement Management processes in response to
faster project cycle times, de-emphasizing
Reliability Validation, Failure Analysis
Resolution and Standard Part Program processes -
specifically those associated with flight lot
qualification -reducing our ability to quantify,
understand and manage risk.
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Resulting Products
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Study Summary

• Analyzed agency needs for primary and secondary
  parts engineering process
• The results were used to create a ranked list of
  risk factors
• Risk factors used to identify and prioritize
  products
• Established NEPAG objectives
• Formed the basis of the NEPAG program plan
  

11
NEPAG Charter

• It is the role of NEPAG to
• Provide knowledge, tools, information and access
  to resources to enable the project parts
  engineers and parts specialists to optimally
  support the circuit designers
• AND to
• Promote processes which will exclude quality and
  reliability part failures from the advanced
  stages of the project life cycle.

12
NEPAG Objectives

• To
• Establish an inter-agency working group of lead
  parts engineers from NASA Centers and JPL for
  agency-wide coordination of parts issues
• Develop information technology-based
  communication system and tools to increase
  efficiency
• Create a knowledge-base of part supplier quality
• Develop assurance tools for COTS parts
• Guidelines procedures for qualification
• Shared knowledge of qualification results
• Knowledge-base on current COTS industry products
  and trends
• Provide support to the MIL system
• Maintain a current NASA EEE parts selection list
• Influence Non-government standards bodies through
  active participation
• REDUCE INCIDENCE OF EEE PARTS FAILURE

13
NEPAG Organization Chart
NEPAG OfficeGSFC Mike Sampson
NASA ARC Ron Chinnapongse
NASA GRC Vince Lalli
NASA GSFC Greg Rose
NASA JSC David Beverly
JPL David Peters
NASA LaRc Otis Riggins
NASA MSFC Charles Gamble
NASA KSC Eric Ernst
USAF/SMD Dave Davis
NAVSEA Crane Darren Crum
ESA John Kaëlberg
NASDA Sumio Matsuda
This is a GROUP, a cooperative affiliation
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NEPAG/NEPP Interaction
NEPP (Program/Project Future Needs)
Needs, Feedback
Reliable Hardware in Missions
Infusion Path
NEPAG (Program/Project Routine and Emergency
Needs)

• NEPP
• New technology insertion risks
• Radiation susceptibility
• Thermal constraints
• Packaging failure modes
• Emerging technology reliability input
• New packaging failures - redesign
• New COTS failure modes and mechanisms in NASA
  environments
• COTS assessment methodologies

• NEPAG
• Continuing Reliability of Parts in Use by the
  Agency
• Design/Manufacturing Change Impact
• Vendor/Supplier Quality Data
• Vendor Audit Knowledge
• Alerts
• Flight Heritage
• Acceptance Criteria
• Screening, Qualification Processes
• Problems, Mitigation
• Emerging Issues

15
FY01 Activities

• Information Technology Infrastructure
• NEPAG website firmly established
  http//eee.larc.nasa.gov/forum/
• Interactive
• Currently it is primarily a tool for NEPAG
  members
• Products (tools and information) will be offered
  in a public area whenever possible
• Guidelines, Tools
• NPSL updating in process - Public
• Risk Management of supply chain
• Task added for FY01in reaction to obvious need
• MIL specification and standards control
• NGS activity - monitoring, participation and
  promotion of space perspective
• Audit and Survey support
• Telcons
• Weekly with all NASA participants, USAF, Navy
  Crane
• Monthly with ESA and NASDA to work global issues

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FY01 Activities (contd.)

• DC/DC Converters
• Plan developed to refocus towards short term and
  intermediate aids for the procurement of reliable
  parts
• NEPAT
• Study of Reverse Polarity Behavior of Tantalum
  Capacitors (2 recent occurrences)
• Recurring problem, error proofing seems difficult
• Life expectancy under derated conditions
  indefinite
• Negligible published data, especially for SMT
  chips
• Contribution to GSFC Tin Whisker Experiment
• Important for lead-free initiative
• SEM examination of 2-year old whiskers
• Whisker found growing through conformal coating
• NPSL Parts Addition
• Developing process to provide an infusion path
  for selected NEPP products
• Evaluated products that are potentially
  qualifiable section

17
Issues and Concerns

• Lack of good NASA-wide parts problem data
• Where to concentrate resources?
• What problems to attack?
• Lead-free - the pure tin option risks tin
  whiskers
• MIL and NGS specification change systems have
  inadequate government participation/oversight
• Dominated by manufacturers and low REL users
• Semiconductor power ratings increased without
  demonstrated reliability
• Key tests such as Residual Gas Analysis proposed
  for deletion
• MIL adoption of inadequate industry standards
• Aging tools
• Derating - still using MIL-STD-975, not updated
  since 95, canceled in 98
• Reliability - still using MIL-HDBK-217, not
  updated since 92
• Inappropriate use of COTS
• For cost not performance
• With inadequate screening and qualification

18
Parts Issues by Calendar Year
19
Pareto of Problem Commodities 1991-2000
20
Lead Free

• Being promoted by Japan, OSHA and Europe
• Electronics is a minor hazard source
• Several concerns for space applications
• Thermal cycle durability of lead free solder
  joints, especially surface mount
• Effect of soldering process on components,
  especially higher temperatures
• Use of pure tin plating
• Tin Whiskers
• Tin Pest

21
Tin Whiskers - Its Alive!

• Whiskers have been an issue in electronics since
  1946
• Cause shorts in low current applications (lt10mA)
• At higher currents cause glitches as they fuse
  open
• Loose whiskers are hazardous contaminants in
  spacecraft
• Satellite Failures Due to Plasma Arcs Experienced
  in the 1990s
• Plasma Arcs can conduct hundreds of amps in space
  vacuum
• Whiskers are a few microns in diameter (typical
  1) and up to several millimeters in length
  (typical 1)
• Risk is greatest with pure tin
• Companies say they must go lead-free soon (months
  not years)
• Many commercial parts already plated with pure
  tin
• EIA G-12 Committee requested to support
  re-instatement of a pure tin option in the
  plating specifications for military products-
  Heavily contested by NASA
• Several platers offering whisker- free tin
  plating, typically called matte tin
  -effectiveness unknown

22
The Fact Remains - Tin Will Whisker

• Freedom from whisker growth cannot be expected
  for pure tin, cadmium or zinc.
• The incubation period for whiskers has been
  observed to be days to years
• Tin whisker growth is enormously variable and its
  controlling factors are not understood
• Reflow is often recommended for the elimination
  of whiskers but long term studies have shown this
  is not a complete fix - scratches can initiate
  whiskers

Conformal coating delays the risk but whiskers
can grow through it. Low voltage circuits and
ultra-small lead spacings heighten NASAs
susceptibility to whisker related failure
23
Tin Pest

• Tin exists in two forms or allotropes
• Metallic - hard, shiny, conductor
• Non-metallic powder - soft, gray, semiconductor
• Transition between two forms is temperature
  dependent
• Cold phenomenon
• Begins to occur at about 13C
• Conversions speeds up as temperature falls,
  maximum rate occurs at -30 C
• The powdery form has no strength and tin objects
  stored at low temperatures can disintegrate
• Process accelerated by presence of powder form
  which acts as a self-catalyst

24
Specifications and Standards

• The MIL system is not dead but it is neglected
• The coordination system became weak after
  acquisition reform
• Preparing, custodian and review activities
  reassigned?
• NGS bodies poorly attended by NASA and other
  spaceflight interests
• Result in changes that may not be good for space
  applications
• Class T - MIL-PRF-38535 - opposed by NASA
• Higher power ratings - MIL-PRF-19500 -opposed by
  NASA unless no deterioration in reliability can
  be demonstrated
• Tin Plating - opposed by NASA

25
FY02 Plan Highlights

• Information Technology
• Expand website capabilities, particularly
  interactively
• Transition products to public area
• Add parts problem database
• Plan NASA-wide parts engineers database
• Resources
• Obtain or develop parts expertise in the top risk
  commodities
• NASA Parts Selection List
• Improve Usability and Searchability
• Update and add new parts
• Add technology infusion path for NEPP products
• Lead-free
• Task to evaluate commercial platings - samples
  for whisker farm

26
Conclusions

• NASA has reinserted itself into the global EEE
  parts arena at the right time
• Risk management of EEE parts for space
  applications requires attention to detail
• Old problems will reappear. We must be vigilant
• Our concerns are shared by an international
  community
• NASA Parts assurance needs improved tools to
  remain effective in this environment of scarce
  expertise, rapidly changing technology and
  varying priorities