Failure Mechanisms, Acceptance Criteria, and

Accelerated Test Procedures for Electronic

Components Used in Active Implantable Medical Devices: Capacitors

Grady WhiteSMTA/MEPTEC

Medical Electronics Symposium

September 17, 2009

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Overview• Medical Electronics Trends

• Growth Drivers• Technology Trends• Technology Integration Plans

– Key Technology Gaps– Initial Projects

• Component Reliability Specifications Project overview

• Medical Reliability for MLCC (multi-layer ceramic capacitor) Project Update

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Medical Electronics Trends - Growth

Source: Bureau of Labor Statistics, pub in CNN/Money.com, “Where the jobs will be Greatest employment growth is likely to be in service industries, according to new labor study.” By Jeanne Sahadi, Feb 13, 2004.

• Medical related job demand fastest growing• Inadequate supply of labor

• Costs are critical• Rising hospital care costs, • Escalation in the number of un-

insured, • Shorter healthcare giver – patient

interaction time.

• Growing “Consumer Medical Electronics Market” • home diagnostic equipment,

wearable patient equipment, etc.

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Medical Technology Drivers

Category DescriptionMedical TherapyTherapy managementPatient EligibilityAvailability

SOLUTION Hardware & Software

SUPPORT Technology Access

MARKET

Before Today (2006) Future (2012)Necessity Reactive ProphylacticCaregiver Caregiver/patient AutomatedCriticality driven Comfort driven Wellness/risk driven

Developed Nations Developing Nations

Local Global Global <--> g'local

DeviceTherapy specific

SystemLimited convergence

Multi-systemIntegrated / convergent

Newly formed markets, new technologies are in developmentPRE-COMPETETIVE INDUSTRY COLLABORATION IS VITAL

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Medical Technology Drivers

Category DescriptionMedical TherapyTherapy managementPatient EligibilityAvailability

SOLUTION Hardware & Software

SUPPORT Technology Access

MARKET

Before Today (2006) Future (2012)Necessity Reactive ProphylacticCaregiver Caregiver/patient AutomatedCriticality driven Comfort driven Wellness/risk driven

Developed Nations Developing Nations

Local Global Global <--> g'local

DeviceTherapy specific

SystemLimited convergence

Multi-systemIntegrated / convergent

Newly formed markets, new technologies are in developmentPRE-COMPETETIVE INDUSTRY COLLABORATION IS VITAL

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Gap Identification -Implantables

Legend

Green – Gap Issues Resolved

Yellow – Known Gap mitigation techniques

Red – No known solution; development required

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Gap Identification -Implantables

Legend

Green – Gap Issues Resolved

Yellow – Known Gap mitigation techniques

Red – No known solution; development required

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Medical Component Reliability

Specifications Project

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Medical Component Reliability Specifications Project

Object: • To leverage industry knowledge to create a minimum set of

requirements for electronics components for application in life critical applications

• This will allow component suppliers access to the entire industry by providing commonly accepted accelerated testing, extrapolation analysis, materials and processes

• Medical device manufacturers will achieve proven quality and reliability from these components– Choose Multi-Layer Ceramic Capacitors (MLCCs) as first example

of this approach

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Medical Components Reliability Specifications Project

Project Members (SOW)

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Medical Components Reliability Specifications Project

Project Suppliers

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Medical Component Reliability Project Process

Supplier Methods, Processes, Risks

• Raw Materials (e.g. for capacitors Ceramic, Tantalum, Terminations)

Existing Standards• Supplier Plan• Component Reliability and

Assessment

Use Conditions• Manufacturing Process & Testing• Storage (before / after assembly)• RoHS Compliant Requirements • Operating (In Use)

Accelerated Testing and Extrapolation Methodology• Sampling/population assessment• Conditions of Applicability• Test Methodology and Criteria

CO

MPO

NEN

T R

ELIA

BIL

ITY

PRO

JEC

T TE

AMINPUT OUTPUT

Medical Grade Specifications

Phase I: data used to create the working test DOE

matrix

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Failure Modes and Effects Analysis (FMEA)• FMEA

Procedure by which each potential failure mode for a given component within the system is analysed to determine the effects on the system, potential risk to the patient or user, failure causes, and associated prevention controls

– Failure Mode• The Failure Mode is the manner by which component failure is

observed or characterized

– Potential Effect(s)• A Potential Effect is the consequence a Failure Mode has on the

safety or functionality of the device

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FEMA: compilation from four companies

INTRINSIC Importance

Cracks 1

Leakage 1

Termination defects 2

Solder issues 3

Drift out of specifications 3

Electrodes 4

EXTRINSIC

Customer application 1

Mechanical treatment 1

UNKNOWN

Undetermined 1

Further insights:

1. The feeling among all manufacturers is that “Leakage” results from cracking

2. It is not clear how cracks lead to increased current leakage

3. It is not clear what cracks lead to failure and what cracks may be benign

4. “Termination defects” and “Solder issues” appear to be processing defects and should be screened out relatively easily

5. “Drift” is a time-dependent failure process

6. Both of the Extrinsic failure sources derive from brittle mechanical failure

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Use Conditions for Life Critical Medical Components

Manufacturing, storage, and use parameters that could affect reliability:

• Mechanical• Thermal• Electrical• Environmental• Biocompatibility

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Review of existing and related Standards and Test Methods

AEC – ZERO DEFECTS GUIDELINE – AEC-Q004

– STRESS TEST QUALIFICATION FOR PASSIVE COMPONENTS – AEC – Q200

– FAILURE MECHANISM BASED STRESS TEST QUALIFICATION FOR INTEGRATED CIRCUITS – AEC – Q004

HDBK– MILITARY HANDBOOK - ENVIRONMENTAL STRESS SCREENING (ESS) OF ELECTRONIC EQUIPMENT -

DOD – HDBK – 344(USAF) MILITARY HANDBOOK

– DEPARTMENT OF DEFENSE HANDBOOK ENVIRONMENTM-J STRESS SCREENING PROCESS FOR ELECTRONIC EQUIPMENT THIS HANDBOOK – MIL- HDBK-2164A

– MILITARY HANDBOOK – ENVIRONMENTAL STRESS SCREENING (ESS) OF ELECTRONIC EQUIPMENT -MIL-HDBK-344Ai

GEIA - Government Electronics & Information Technology Association– ANSI/GEIA-STD-0003 Procedures for Long Term Storage and Electronic Devices

– ANSI/GEIA-STD-0005-1 Performance Standard for Aerospace and High Performance Electronic

Systems Containing Lead-free Solder

– ANSI/GEIA-STD-0005-2 Standard for Mitigating the Effects of Tin Whiskers in Aerospace and

High Performance Electronic Systems

Others

DOE Formation• Phase 1 testing

– As a result of the DOE formation, FMEA, Pareto, and Use Conditions, preliminary experiments were performed on test boards / components. Initial testing was performed to give input to phase II PCB design, electrical hardware setup and criteria for failure.

– Measured as received and pre-stressed components. Subjected to high temp and bias to determine leakage breakdown.

– Performed at NIST Boulder

• DOE Completion (128 Cell Matrix)

– Optimized to balance variables (Texas Instruments performed the analysis using Jmp Software)

– Main variables are: (Temp, Vibration, forming gas, Voltage, Voltage type AC/DC, number of reflows)

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MLCC Project DOE Matrix

Variables and Levels based on FMEA and Medical use conditions

Couponnumber= row

number X1=Vibration X2=Temperature X4=Voltage X6=Cyclic_Voltage X5=Atmosphere_Precondition X3=Humidity_Precondition X7=Vendor X8=Number_of_reflows1 YES 125 C 96 volts 1500,50% Biphasic Forming Gas NONE Vendor C 3 reflows2 YES 85 C 6 volts DC NONE NONE Vendor A 3 reflows3 YES 125 C 6 volts DC Forming Gas NONE Vendor C 3 reflows4 NO 125 C 96 volts DC NONE NONE Vendor B 3 reflows5 NO 125 C 96 volts DC NONE NONE Vendor C 2 reflows6 YES 85 C 6 volts DC Forming Gas 85 / 85 Vendor C 3 reflows7 NO 125 C 6 volts 1500,50% Biphasic NONE NONE Vendor B 3 reflows8 YES 85 C 6 volts DC NONE 85 / 85 Vendor C 2 reflows9 YES 125 C 6 volts 1500,50% Biphasic NONE 85 / 85 Vendor A 3 reflows

10 YES 125 C 96 volts DC Forming Gas 85 / 85 Vendor B 3 reflows. . . . . . . . .. . . . . . . . .

128 YES 85 C 96 volts DC Forming Gas NONE Vendor C 2 reflows

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Medical Reliability for MLCC Project (Phase II)Scope of Work: • Specific deliverables of Phase II include the following:

– Creation of a test vehicle• Design of Test board• Fabrication of Test vehicle• Population of test board with functional MLCC’s

– Creation of fixtures and test equipment cables and peripherals at NIST– Testing of DOE variables from Phase I at NIST Boulder Facility– Completion of screening experiments at NIST.

– Collection of Data and Data Mining resulting failures for trends and insight

– Failure analysis of Test output “Failures as defined in Phase I”

– NIST coordinate Failure Analysis Suppliers– Phase II Report

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MLCC Phase II – StatusTest Coupons designed and populatedPre-DOE electrical test conducted on all 128 coupons

• Insulation Resistance• Capacitance• Dissipation Factor

DOE tests run on 34 coupons• Two apparent degradation processes observed• No capacitor failures (i.e., x10 increase in ileakage)• Selected capacitors returned to vendors for Failure Analysis

Non-DOE activities• Aggressive test conditions of 96 V, 160 oC

• Expected failures observed• Ultrasonic resonance measurements

• As-received and after tests• Change in resonance pattern observed

We expected to see

Monotonic increase in leakage current (VR/R = ileakage) over time

What we actually see1. Increasing transients w/time under

load

2. Increasing width of noise band (excluding transients) w/time

3. Most capacitors show one of these tendencies

- degree varies considerably among capacitors from the same manufacturer and subjected to the same test conditions

- Initial capacitor degradation leading to failure(?)

DOE Capacitor Behavior over Time

VRR

VapplC

Compare with Test at 96 V and 160 oC:

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Observe Expected Failure Behavior

X10 increase in ileakage as capacitor starts to fail

Ultrasonic Resonance Spectra: As-Rcvd vs. Failed

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As-Received Capacitors:- Four capacitors measured- Peak positions highly reproducible

- Range 25 KHz- Amplitudes dependent on mounting

- Spectrum details mfg dependent

Failed Capacitor:- Details vary from capacitor to capacitor- Common features

- First 2 peaks reduced/shifted- Peaks appear for 1500 KHz ≤ f ≤ 1800 KHz

- Frequently peak clusters appear around f ~ 2600 KHz

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Resonance Spectra: As-Rcvd vs. HarvestedHarvested Capacitor:- Details vary from capacitor to capacitor- Common features

- First 2 peaks reduced/shifted- Peaks appear for 1500 KHz ≤ f ≤ 1800 KHz

- Frequently peak clusters appear around f ~ 2600 KHz

SUMMARY:- As-Rcvd capacitors reproducible enough to provide baseline- Spectra of harvested/failed capacitors vary but always shift first 2 peaks and produce peaks in gaps of the As-Rcvd spectra

IMPLICATIONS:Resonance spectra may provide NDE technique to monitor degradation or provide acceptance criteria

Ongoing Plans

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Close out Phase II:- DOE parameters

- Not aggressive enough to generate failures in 1,000 h test- Observe damage onset

- Observe classic failures using 96 VDC and 160 oC- Preliminary data suggests ultrasound may provide NDE/Acceptance Criteria test

Initiate Phase III:- Continue DOE tests to obtain capacitors for failure analysis FA under varied load conditions- Obtain FA data

- Compare damage in harvested and failed capacitors- Compare damage to that seen in field failures- Correlate damage with ultrasonic spectra

Identify parameters to provide relevant accelerated failure tests for acceptance of capacitor batches and/or develop NDE test for individual

capacitor acceptance

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Invitation

Industry First collaboration within medical electronics supply / value chain

We encourage any organization that would like to participate in this activity to contact :

David Godlewski, iNEMI

717-651-0522

dgodlewski@nemi.org

or the contacts on the next slide

www.inemi.orgEmail contacts:

Jim McElroy jmcelroy@inemi.org

Bob Pfahlbob.pfahl@inemi.org

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