# Presentation: 285882

## Enabling COTS Parts Insertion in NASA Systems:A Combined NEPAG (Q, AE) – NEPP Program (AE) Activity

***Enabling COTS Parts Insertion in NASA Systems:******A Combined NEPAG (Q, AE) – NEPP Program (AE) Activity***

**Chuck Barnes****NEPP Program Manager****Jet Propulsion Laboratory****California Institute of Technology****Pasadena, CA**
**and**
**Mike Sampson****NEPAG Program Manager****NASA Goddard Space Flight Center****Greenbelt, MD**
**NASA S&MA Directors’ Meeting****Dryden Flight Research Center****October 10, 2002**

- COTS: Commercial Off-The-ShelfNEPAG: NASA EEE Parts Assurance GroupEEE: Electronic, Electrical, ElectromechanicalNEPP: NASA Electronic Parts and Packaging

## Outline

**Outline**

**NEPAG and NEPP Objectives and Organization**
**NEPAG and NEPP Relationship**
**Use of commercial off-the-shelf parts in space**
**NEPAG/NEPP COTS Evaluation Activity**
- Approach
- Upscreen Flow
- Results
- Glass Transition Temperature Results
- Breakdown Voltage
- C-Mode Scanning Acoustic Microscopy (C-SAM) Results
**Conclusions**

## NEPAG Charter and Objectives

***Charter***
- Provide knowledge, tools, information and resources to aid project EEE parts engineers and parts specialists in guiding parts selection decisions by designers and projects
- Promote quality and reliability assurance processes to eliminate EEE part failures from the advanced stages of the project life-cycle
***Objectives***
**Reduce incidence of EEE parts failure through**
- Establishing an inter-agency working group of parts engineers from NASA Centers and JPL for agency-wide coordination of parts issues
- Developing information technology-based communication system and tools to increase efficiency
- Creating a knowledge-base of part supplier quality
- Developing assurance tools for COTS parts
- Maintaining a current NASA EEE parts selection list (NPSL)
- Influencing non-government and government standards bodies*** ***

## The NASA EEE Parts Assurance Group (NEPAG)

**NASA HQ Code Q**
-  Tom Whitmeyer

**The NASA EEE Parts Assurance Group (NEPAG)**

## NASA Electronic Parts and Packaging (NEPP) Program

_***Program Objectives***_
- Assess the reliability of newly available commercial off-the-shelf (COTS) electronic parts and packaging technologies
- Evaluate advanced and emerging parts and packaging technologies to expedite their readiness for infusion in NASA systems
- Develop new methods and processes for parts and packaging evaluation, selection, and qualification.
- Disseminate quality assurance, reliability, radiation tolerance, validation, tools and availability information to the NASA community
_***Program Features***_
- $9.4M/yr Program funded by the NASA Chief Engineer’s Office (Code AE)
- Multi-Center Program - 80 to 85% of work at JPL and GSFC
- JPL is coordinating Center
- Program focus on TRL 3 to 6
- Collaborations with DoD, Industry and Academia
- Program content determined by both a proposal review process and by strategic shaping
- Program made up of 4 projects – Parts Project, Packaging Project, Electronics Radiation Characterization Project and Information Management and Dissemination Project
- Program focus is from individual part/component up to board level

_**Technologies**_
-  Newly Avail.             Advanced,
- COTS                      Emerging
- Evaluation AgainstEnvironmental & PerformanceRequirements
- Information Dissemination
**Insertion in NASA****Flight Project Equipment**

## NEPP Program Organization

## Relationship of NEPAG and NEPP

***Flight Project Evolution***

**Relationship of NEPAG and NEPP**

## Reasons for COTS Use in Space

**Large, standardized software base**
**“****Lower” cost, “quicker” delivery**
- Although upscreening can stretch delivery and raise cost substantially
- Parts are small fraction of total satellite/spacecraft cost (5 to 10%), but this cost will be relatively higher in future
**Rad-hard processing lines that do exist are 1 to 2 generations behind**
**Greater government reliance on industry standards and specifications for part procurement (Perry Directive)**
**For NASA, paradigm of “Better, Faster, Cheaper” allows for risk management at system level, rather than complete elimination of risk, and requires quick, inexpensive procurements**

**Access to high performance, state-of-the-art microelectronics **

## Relative Size of Space Market for Microelectronics

**Relative Size of Space Market for Microelectronics**

## Problems with Use of COTS in Space

**Life cycle costs can actually be higher for COTS-intensive spacecraft due to added testing, part and system failure, system re-work, added cost of shielding**
**Reliability data on COTS is often unknown or unavailable to small customers**
**Lot traceability is often impossible with devices from the “same” lot that are actually made on different fabrication lines**
**Process changes unknown to the customer can result in reduced reliability and radiation tolerance**
**Variations between lots over time can nullify the validity of testing performed on a lot prior to purchase of a flight lot**
**Even for parts with satisfactory reliability and radiation tolerance, packaging can cause problems in the space environment**
**Simple passives -  capacitors, resistors -  can cause failures on the board or internal to hybrids**
- Recent experiences with DC-to-DC converters
**Commercial competitiveness to reduce cost, improve performance can jeopardize availability of specific parts required in future systems**
**Space applications do not usually allow for repair or replacement**
- Hubble Space Telescope, Shuttle and International Space Station are exceptions
**Radiation degradation can’t be solved by leveraging off other high-reliability, high volume users (automotive industry)**

## Enabling COTS Parts Insertion in NASA Systems:NEPAG/NEPP COTS Evaluation Activity

**NEPAG and NEPP are working together to evaluate the practical and technical issues surrounding use of COTS in NASA systems**
- Practical issues
- Surveys of test houses (capabilities, handling procedures etc.)
- Surveys of distributors (how do they do business?)
- Visits to manufacturers (how do they collect their data?)
- Cost/benefit comparison for typical screens and qualification Tests
- Proper and effective oversight/insight into vendors, distributors and test houses
- Technical issues
- Validation of vendor part technical data
- Analysis of upscreening steps and philosophy for added value in the NASA environment
- Detailed investigation of selected upscreening steps and failure mechanisms revealed by these steps
**Objectives**
- Establish guidelines for how/if NASA can reliably select/test/apply Commercial-Off-The-Shelf (COTS) and Plastic Encapsulated Microcircuits (PEMs)
- Establish methods for assessing the validity/applicability of vendor supplied qualification/test data for COTS/PEMS technologies
- Determine appropriate upscreening flows for NASA applications

## NASA Unique Approach

**The NEPAG/NEPP approach to evaluating COTS and upscreening for space is unique compared to other studies in that we will **
- Gather a complete data set on the same sample of COTS devices, using established methods to measure the assembly, materials, design, performance, and reliability attributes
- Provide detailed evaluation of upscreening steps and their added value or lack thereof, and the failure mechanisms mitigated by these steps
- Assess robustness of parts evaluated by drawing any correlations between any failures (or lack thereof) and the inherent manufacturer’s advertised quality and reliability
- Establish  NASA guidelines for using COTS in space applications, utilizing a risk posture approach for different critical and non-critical missions and then making recommendations on how to mitigate the risk according to the mission requirements

## NEPP/NEPAG COTS Evaluation

**Approach**
- NEPAG is focusing on passives (capacitors, resistors) while NEPP is concentrating on active microcircuits
- Team approach used for major decisions and tracking
- Establish NEPAG/NEPP team for deciding on major task steps, parts selection, test house selection, upscreening flow details
- Representatives from: GSFC, JPL, ARC, GRC, JSC, KSC, LaRC, MSFC, USAF, Aerospace Corp., TRW, APL, NAVSEA, ESA, NASDA
- Tracking teams for test houses and data established for passives and actives
- Procure devices for evaluation based upon actual NASA program needs
- Passives are Base Metal Electrode (BME) ceramic chip capacitors
- 0805 and 0402 Chip Sizes
- 6.3 V to 50 V Ratings
- Four Different Manufacturers (+ 2 High Rel Suppliers)
- Actives are all plastic encapsulated microcircuits (PEMs)
- 8-bit high speed, low power Analog/Digital Converter (ADC1175)        •    Device spares already requested by a flight project
- 16 channel analog multiplexer (MAX306)
- High speed operational amplifier (LT1468)
- High precision voltage reference (AD780)
- High common mode voltage difference amplifier (INA117)
- Survey manufacturers and review “internal” qualification process and test data
- Subject selected devices to extensive screening/qualification/evaluation test protocol as an “independent” verification of the vendor’s qualification and to determine added value of individual screening steps
- Publish results in the form of a NASA Guideline Document for Proper Selection & Qualification Methodology for COTS/PEMS devices

## Outline of PEMs Upscreening Test Flow

## NEPP/NEPAG COTS Evaluation

**Phase 1 status**
- Two active and two passive device manufacturers visited/surveyed
- Some vendors allow communication only through distributors
- As indicated on title page, “Lots” may be mixes from various lines/locations
- Big problem for high reliability, radiation tolerant applications such as NASA flight systems
- Vendor data reviewed
- Life testing is done on high runners (mature parts)
- Data exclusion rules used to stop “freak” lots from upsetting failure-in-time (FIT) calculations
- Sample quantity, test duration, test conditions and frequency of testing vary widely between vendors
- Sampling (or not) from lines, locations, wafer fabs or package styles can be random
**Published FIT values applicability to procured product is vendor and part type dependent and may be unknown**
- NEPP/NEPAG screening/qualification testing in progress
- Several test houses were visited and two were selected for actives, one for passives
- Selection process mimics what flight project would do
- Identify problems with test houses – already demonstrated value of having regular onsite inspections of work
- Actives
- Destructive Physical Analyses (DPAs) have been completed
- Initial electrical characteristics look good but data have not been analyzed in detail
- PEMs encapsulant glass transition temperatures vary widely and do not always agree with vendor data
- Passives (capacitors)
- One lot failed to meet dissipation factor limit during initial electricals
- One DPA lot showed a proportionally large delamination

## Measurement of PEM Glass Transition Temperature

**Measurement of PEM Glass Transition Temperature**

## Features/Issues for Tg Results on Five Microcircuits

**Each sample is from a different manufacturer**
**The Glass Transition Temperature (Tg) values vary more than was anticipated according to vendor data**
**One manufacturer expressed surprise at the low value as their policy was to control Tg to >160C**
**117C is below the standard burn-in and test temperature NASA often uses for space parts – 125C and the Tg we desire of 145C which provides a 20C margin to the burn-in**
**The high thermal expansion above the Tg value raises reliability concerns such as:**
- Excessive stress on wire bonds
- Delamination between encapsulant and lead frame or die paddle
- Excessive stress on the die
**Other reliability concerns when transition temperature is exceeded are**
- CTE of epoxy encapsulant will permanently change (breakdown of chemical cross-linking of polymers)
-  Displacement of wire bonds resulting in a premature wear-out  and breakage of wires
-  Premature aging (e.g. storage)
-  Induced stresses between materials internal/external) because of CTE mismatch; reduces temp. cycling capability
-  Adhesion degradation
-  Release of Bromine, Red Phosphorous (flame retardants); can cause corrosion, lifted bonds due to release of ionics)
-  Device performance degradation

## COTS Capacitor Tests – Breakdown Voltage vs. Dielectric Thickness 

**COTS Capacitor Tests – Breakdown Voltage vs. Dielectric Thickness **

*Tests of 12 lots of ceramic capacitors*

- PME = Precious Metal ElectrodeBME = Base Metal Electrode

## Additional Recent Results

**DPA Results**
- Contrary to the vendor’s website advertisement, pure tin was found on two device types of the five being tested (this is a prohibited material for NASA applications)
- Contrary to the vendor’s website advertisement, glass transition temperatures for  the epoxy compound on two device types were below the industry norm
- As noted earlier, this can cause reliability problems
- Unplated areas of  base lead frame metal (can lead to corrosion, oxidation, etc.)
- One device used steel as the base material for the lead frame as opposed to alloy 42 and copper materials normally used by most vendors
**Screening Results**
- Significant value has been demonstrated for having regular onsite NASA oversight/insight into testing
- For one device type, 500 parts were procured from distributor
- Three different date codes were supplied
- Electrical verification to the vendor’s data sheet advertised limits showed two date codes met the limits, while one date code experienced 16 failures out of 250 tested
**C-Mode (horizontal scan) Scanning Acoustic Microscopy (C-SAM) Inspections**
- One device type has completed CSAM tests
- Results show all 250 devices have delamination problems which exceeds industry acceptable standards
- >10%  delamination is unacceptable

## NEPAG/NEPP ADC1175CIJM C-SAM Accept and Reject Examples

## Conclusions

**Early results already show that vendor data cannot always be trusted**
**Observed low glass transition temperature results suggest potential severe reliability problems especially for use of burn-in to eliminate bad parts**
**Multiple date codes within a lot buy have demonstrated significant variations in quality and reliability**
**Capacitor voltage breakdown data has shown variations from one manufacturer to another that may result in reliability problems**
**C-SAM results show extensive delamination problems**
- Important result from the point of view of test value since C-SAM has been controversial in terms of its value added
**These results are from very early analysis of test results and we expect additional significant insights into the upscreening process for COTS parts**