# Presentation: 091377

## 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: 301-286-1667
- msampson@pop300.gsfc.nasa.gov

## Overview

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

- NASA EEE Parts Assurance Group (NEPAG)

## NASA Parts Project Office
Mid 80’s 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

- Mid 80’s 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***

**Origins**

## 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 

- 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

**The Changing World of ****EEE Parts Assurance**

## 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

- 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

**A New Start**

## 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

- 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

**The Study**

## Critical EEE Parts Processes Identified by Analysis

- 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

**Critical EEE Parts Processes ****Identified by Analysis**

## 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.*

## Resulting Products

**Resulting Products**

## 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

## 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.

## 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

## NEPAG Organization Chart

**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

**NEPAG Office****GSFC**
**Mike Sampson**

**This is a **_**GROUP**_**, a cooperative affiliation**

## NEPAG/NEPP Interaction

**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

**NEPP**** ****(Program/Project Future Needs****)**

**NEPAG**
**(Program/Project Routine and Emergency Needs)**

**Needs, Feedback**

**Reliable Hardware**
**in Missions**

**NEPAG/NEPP Interaction**

**Infusion Path**

## 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

## 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

## 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

## Parts Issues by Calendar Year

## Pareto of Problem Commodities 1991-2000

## 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

## Tin Whiskers - It’s Alive!

**Tin Whiskers - It’s Alive!**

- Whiskers have been an issue in electronics since 1946
- Cause shorts in low current applications (<10mA)
- 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 1990’s
- 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

## 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 NASA’s susceptibility to whisker related failure**

## 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  13°C
- 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

## 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

## FY02 Plan Highlights

- Information Technology
- Expand website capabilities, particularly interactively
- Transition products to public area
- Add parts problem database
- Plan NASA-wide parts engineer’s 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

## 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