characterization of tantalum polymer capacitors€¦ · • polymer pros and cons • data gathered...

Characterization of Tantalum Polymer Capacitors

Penelope Spence, Office 514

Jet Propulsion Laboratory California Institute of Technology

Pasadena, California June 11, 2012

Copyright 2012 California Institute of Technology. Government sponsorship acknowledged.

Mission Assurance Office Section 514

Agenda

• Overview

• Polymer Pros and Cons

• Data Gathered to Date

• Plan Moving Forward

• Summary and Conclusions

Spence, 6/11/2012, NASA Electronic Parts and Packaging Electronics Technology Workshop 2


Overview

• MIL-PRF-55365 Tantalum MnO2 Capacitors


• Tantalum Polymer Capacitors: MnO2 cathode is replaced with polymer material

* “Replacing MnO2 with Conductive Polymer in Tantalum Capacitors,” CARTS Europe 1999 * “Capacitor Types, Construction, and Characteristics,” KEMET KIT 2011


Polymer Pros and Cons

• Pros – No ignition problems – Lower ESR – Less stress during manufacturing (low-temperature deposition)

• Cons – Less thermally stable – Higher leakage current – Moisture Sensitivity Level 3 (168 hours ≤ 30°C / 60% RH)



Failure Distribution of 6 V Capacitors


* “Reliability of Tantalum Polymer Capacitors,” CARTS USA 2004

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.01 0.1 1 10 100 1000

9.6V, 105°C10.8V, 105°C11.4V, 105°C12.0V, 105°C12.6V, 105°C

9.6V10.8V

11.4V12.0V

12.6V

Time (hours)

Norm

al P

erce

ntile

Lognormal Plot of Failures vs. Time-To-Failures, 6 V Tested at 105°C

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.01 0.1 1 10 100 1000

8.4V, 125°C 9.6V, 125°C10.8V, 125°C

8.4V9.6V10.8V

Time (hours)

Norm

al P

erce

ntile

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.01 0.1 1 10 100 1000

6.0V, 145°C 7.2V, 145°C 8.4V, 145°C 9.6V, 145°C10.8V, 145°C

6.0V7.2V8.4V9.6V

10.8V

Time (hours)

Norm

al P

erce

ntile




Characterization of 6 V Capacitors

• Characterized in 2004 by KEMET

• Voltage acceleration, t50 = 1027 years at 85°C and maximum rated voltage

• Temperature acceleration, t50 = 360 years at 85°C and maximum rated voltage



10-1

101

103

105

107

1.0 1.5 2.0 2.5 3.0

165°C, η =10.5145°C, η =12.5125°C, η =14.5105°C, η =16.585°C, η =19.0(85°C) y=9.00e6x-19

(105°C) y=2.00e5x-16.5

(125°C) y=1.20e4x-14.5

(145°C) y=6.50e2x-12.5

(165°C) y=7.95e1x-10.5

X X

8.0hr

650hr

1.4yr

23yr

1027yr

165°C145°C

125°C

105°C

85°C

Multiple of Rated Voltage

Med

ian

Life

[t50

] (hr

s)

10-5

10-2

101

104

107

2.2 2.3 2.4 2.5 2.6 2.7 2.8

XX

Corrected Lines*See Text*

85°C105°C125°C145°C165°C2.1Vr1.9Vr

1.4Vr

1.0Vr

1.2Vr

1.6Vr 2.2Vr2.0Vr1.8Vr

Inverse Absolute Temperature, 1/T (10-3, K-1)

Med

ian

Life

[t50

] (hr

s)

Median Life vs. Test Voltage Median Life vs. Inverse Absolute Temperature


Voltage Acceleration of 4 V and 2.5 V Capacitors

• Partially characterized in 2005 by KEMET

• 4 V capacitors, t50 = 18,000 years at 85°C and maximum rated voltage

• 2.5 V capacitors, t50 = 80,000 years at 85°C and maximum rated voltage


* “Reliability of Low-Voltage Tantalum Polymer Capacitors,” CARTS USA 2005

Median Life vs. Test Voltage, 1000 µF, 4 V, Multiple-Anode

Median Life vs. Test Voltage , 680 µF, 2.5 V, Multiple-Anode


JPL Characterization of 4 V Capacitors


• Main goal: Develop an accurate acceleration model by focusing on accelerated life tests using elevated voltage and temperature

• Secondary goal: Compare two different manufacturers, Manufacturer A and Manufacturer B, to determine if acceleration models are similar

• 220 µF, 4 V tantalum polymer capacitors

Test Matrix 85 C 105 C 125 C

VTest (V) VTest (V) VTest (V) Vlow Vlow Vlow

Vmedium Vmedium Vmedium Vhigh Vhigh Vhigh


JPL Characterization of 4 V Capacitors (A)

• Expected results:


Manufacturer A: 220 µF, 4 V 85 C 105 C 125 C

VTest (V) t50 (hr) VTest (V) t50 (hr) VTest (V) t50 (hr) 10 169 8.8 105 8.8 13

10.8 46 9.6 33 9.2 8.6 11.6 18 10.4 11 9.6 4.5

• Test matrix and resulting t50 times:

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.01 0.1 1 10 100 1000

9.6V, 105°C10.8V, 105°C11.4V, 105°C12.0V, 105°C12.6V, 105°C

9.6V10.8V

11.4V12.0V

12.6V

Time (hours)

Norm

al P

erce

ntile




Failure Distributions for Manufacturer A

Spence, 6/11/2012, NASA Electronic Parts and Packaging Electronics Technology Workshop

Manufacturer A, 220 µF, 4 V tested at 85°C

10

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.0001 0.01 1 100 10000

11.6 V, 85 °C10.8 V, 85 °C10 V, 85 °C

PLS - 3/20/2012Time (hr)

Nor

mal

Per

cent

ile

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.0001 0.01 1 100

10.4 V, 105 °C9.6 V, 105 °C8.8 V, 105 °C

PLS - 3/20/2012Time (hr)

Norm

al P

erce

ntile


0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

1 10 100

9.6 V, 125 °C9.2 V, 125 °C8.8 V, 125 °C

PLS - 9/13/2010Time (hr)

Norm

al P

erce

ntile



Acceleration Models of 4 V Capacitors (A)

• Voltage acceleration, t50 = 23,000 years at 85°C and maximum rated voltage – Comparable to KEMET’s t50 of 18,000 years




100

102

104

106

108

5.0 7.5 10.0 12.5 15.0

85°C, η=15.3105°C, η=14.0125°C, η=13.0y=2.0e8*(x/4) (̂-15.3)y=6.8e6*(x/4) (̂-14.0)y=4.1e5*(x/4) (̂-13.0)

105°C

125°C

85°C

47yr

775yr

23000yr

Applied Voltage (Vdc)

Med

ian

Life

[t50

] (ho

urs)

220uF, 4V Tantalum Polymer (Mfgr. A)

0.01

1

100

10000

2.4 2.5 2.6 2.7 2.8

8.8V, Ea=1.35eV9.2V9.6V, Ea=1.29eV10.0V10.4V10.8V11.6Vy = 3.13E-7*exp((1.35/8.62e-2)*x)y = 5.87E-7*exp((1.29/8.62e-2)*x)

85°C

105°C

125°C

Inverse Absolute Temperature, 1/T (10-3, K-1)

Med

ian L

ife [t

50] (

hour

s)

220uF, 4V Tantalum Polymer (Mfgr. A)2.2Vr

2.0Vr 1.8Vr 1.6Vr 1.4Vr 1.2Vr

1.0Vr


Failure Distribution of 35 V Capacitors


* “Reliability of High-Voltage Tantalum Polymer Capacitors,” CARTS USA 2011

Lognormal Plot of Failures vs. Time-To-Failures, 35 V Tested at 105°C Lognormal Plot of Failures vs. Time-To-Failures,

35 V Tested at 105°C

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.01 0.1 1 10 100 1000

9.6V, 105°C10.8V, 105°C11.4V, 105°C12.0V, 105°C12.6V, 105°C

9.6V10.8V

11.4V12.0V

12.6V

Time (hours)

Nor

mal

Per

cent

ileLognormal Plot of Failures vs. Time-To-Failures,

6 V Tested at 105°C

• 35 V capacitors do not behave as expected


Unexpected Behavior of High Voltage Polymers




• Initial Failures: Increase proportionally to voltage

• Flat Region: Failures occurring slowly over time

• Wear-Out: Region of interest

• Anti-Wear-Out: De-doping of polymer material


Characterization of 35 V Capacitors

• Characterized in 2011 by KEMET

• Voltage acceleration, t50 = 2300 years at 105°C and maximum rated voltage





Nonlinearity of data points for 85°C is evidence that another failure mechanism is at work


Failure Distribution of 25 V and 50 V Capacitors



Lognormal Plot of Failures vs. Time-To-Failures, 25 V Tested at 85°C, 105°C and 125°C

Lognormal Plot of Failures vs. Time-To-Failures, 50 V Tested at 85°C, 105°C and 125°C

• Acceleration models were not generated


JPL Characterization of 4 V Capacitors (B)


• Test matrix and resulting t50 times:

Manufacturer B: 220 µF, 4 V 85 C 105 C 125 C

VTest (V) t50 (hr) VTest (V) t50 (hr) VTest (V) t50 (hr) 10 2,000 10 110 8.8 50

10.8 300 10.8 26 9.2 28 11.6 13 11.6 10 9.6 19 12.4 0.4 - - - -


Failure Distributions for Manufacturer B

Spence, 6/11/2012, NASA Electronic Parts and Packaging Electronics Technology Workshop

Manufacturer B, 220 µF, 4 V tested at 85°C

17



0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.0001 0.01 1 100 10000

12.4 V, 85 °C11.6 V, 85 °C10.8 V, 85 °C10 V, 85 °C

PLS - 3/5/2012Time (hr)

Norm

al P

erce

ntile

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

0.0001 0.01 1 100

11.6 V, 105 °C10.8 V, 105 °C10 V, 105 °C

PLS - 9/28/2010Time (hr)

Norm

al Pe

rcenti

le

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

1 10 100

9.6 V, 125 °C9.2 V, 125 °C8.8 V, 125 °C

PLS - 9/13/2010Time (hr)

Norm

al Pe

rcenti

le


Acceleration Models of 4 V Capacitors (B)

• Voltage acceleration data are questionable for 105°C

• Voltage acceleration data do not support meaningful extrapolation for 85°C

• Test voltages were too high, most likely too close to oxide formation voltage

• Evidence of limits to accelerated testing


Median Life vs. Test Voltage

100

102

104

106

108

5.0 7.5 10.0 12.5 15.0

85°C, η=??105°C, η=16.3125°C, η=10.3y=3.0e8*(x/4) (̂-16.3)y=1.7e5*(x/4) (̂-10.3)

105°C

125°C

19yr

34000yr

Applied Voltage (Vdc)

Med

ian L

ife [t

50] (

hour

s)

220uF, 4V Tantalum Polymer (Mfgr. B)


Unexpected Behavior in 4 V Capacitors (B)


• Two new regions identified: – Overlap of Flat Region and Wear-Out – Wear-Out of Polymer


Anti-Wear-Out in 4 V Capacitors (B)


0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

1 10 100 1000

Post-TTF Median Cap: 38.2µFPre-TTF Median Cap: 232.4µF

PLS - 3/16/2012Cap @ 120Hz (µF)

Norm

al Pe

rcen

tile

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

10 100 1000

Post-TTF Median ESR: 52.4mOPre-TTF Median ESR: 15.1mO

PLS - 3/16/2012ESR @ 100kHz (mOhms)

Nor

mal

Per

cent

ile

• Capacitance and ESR of remaining 4 V capacitors from Manufacturer B tested at 85°C and 10 V


0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

1 10 100

9.6 V, 125 °C9.2 V, 125 °C8.8 V, 125 °C

PLS - 9/13/2010Time (hr)

Norm

al Pe

rcen

tile

Anti-Wear-Out in 4 V Capacitors (B)


• Capacitance and ESR of remaining 4 V capacitors from Manufacturer B tested at 125°C and 8.8 V

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

10 100 1000

Post-TTF Median Cap: 61.3µFPre-TTF Median Cap: 239.9µF

PLS - 3/17/2012Cap @ 120Hz (µF)

Norm

al P

erce

ntile

0.01%0.1%

1%

5%10%20%30%50%70%80%90%95%

99%

99.9%99.99%

1 10 100 1000

Post-TTF Median ESR: 67.3mOPre-TTF Median ESR: 13.8mO

PLS - 3/20/2012ESR @ 100kHz (mOhms)

Norm

al P

erce

ntile


Plans Moving Forward

• Fill the Gap Between 6 V and 25 V Data – Test 10 V and 16 V capacitors from both manufacturers

• Extended Less Accelerated Testing – Different failure mechanisms become active at the same time skewing

the TTF results if the acceleration applied is too harsh – Less severe accelerated testing needs to be conducted to produce more

reliable and meaningful data – This will involve several years of testing since each life test will most

likely run a minimum of 3000 hours

• DPA – Differences in construction, materials, etc.

• Verify KEMET results of 6 V and 35 V capacitors



Summary and Conclusions

• Overview

• Reviewed data

• Caution must be taken when accelerating test conditions – Data not useful to establish an acceleration model – Introduction of new failure mechanism skewing results

• Evidence of Anti-Wear-Out – De-doping of polymer – Decreased capacitance – Increased ESR – Not dielectric breakdown – Needs further investigation

• Further investigation into tantalum polymer capacitor technology

• Promising acceleration model for Manufacturer A – Possibility for use in high-reliability space applications with suitable voltage

derating


characterization of tantalum polymer capacitors€¦ · • polymer pros and cons • data gathered...

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