2017 NEPP Tasks Update for Ceramic and Tantalum Capacitors - - PowerPoint PPT Presentation

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2017 nepp tasks update for ceramic and tantalum capacitors
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2017 NEPP Tasks Update for Ceramic and Tantalum Capacitors - - PowerPoint PPT Presentation

Aug 18, 2023 405 likes •605 views

NASA Electronic Parts and Packaging (NEPP) Program 2017 NEPP Tasks Update for Ceramic and Tantalum Capacitors Alexander Teverovsky AS&D, Inc. Work performed for Parts, Packaging, and Assembly Technologies Office, NASA GSFC, Code 562

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SLIDE 1

2017 NEPP Tasks Update for Ceramic and Tantalum Capacitors

Alexander Teverovsky AS&D, Inc. Work performed for Parts, Packaging, and Assembly Technologies Office, NASA GSFC, Code 562 Alexander.A.Teverovsky@nasa.gov NASA Electronic Parts and Packaging (NEPP) Program

To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology Workshop, Greenbelt, MD, June 2017.

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SLIDE 2

List of Acronyms

To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology Workshop, Greenbelt, MD, June 2017.

AF acceleration factor MLCC multilayer ceramic capacitor BME base metal electrode MOR modulus of rupture DCL direct current leakage PME precious metal electrode ESR Equivalent series resistance QA quality assurance FPGA field-programmable gate array RB reverse bias HALT highly accelerated life testing S&Q screening and qualification HT High temperature SMT surface mount technology HTS high temperature storage TC temperature cycling IDC inter-digitated capacitor VH Vickers hardness IFT Indentation Fracture Test WTC wet tantalum capacitor

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SLIDE 3

Outline

 Update on tantalum capacitors.

  • Leakage currents, gas generation and case

deformation in wet tantalum capacitors.

  • MnO2 chip capacitors:
  • ESR degradation.
  • Acceleration factors for DCL degradation and failures.
  • Effect of moisture on degradation of reverse currents.
  • Polymer capacitors.
  • Future work.

 Update on ceramic capacitors.

  • Mechanical properties of MLCCs.
  • Failures in BME capacitors with defects.
  • Effect of cracking on degradation of MLCCs at HT.
  • Future work.

To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology Workshop, Greenbelt, MD, June 2017.

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SLIDE 4

Leakage Currents, Gas Generation and Case Deformation in Wets

To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology Workshop, Greenbelt, MD, June 2017.

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 NEPP report (https://nepp.nasa.gov/) contains:

  • Part I. Analysis of leakage currents;
  • Part II. Gas generation, hermeticity, and pressure in the case.
  • Part III. Electrolyte at the glass seal.
  • Part IV. Deformation of cases in high capacitance value wet tantalum capacitors.

 Risks of internal leaks: non-oxidized surfaces; corrosion of welds; excessive leakage currents and gas generation.  To reduce failures a special conditioning at HT is recommended.

WTCs with different types of internal seals

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E+2 1.E+3 1.E+4 1.E+5 1.E+6 current, A time, sec

DWG04005 240uF 125V

Anomalies in leakage currents indicate presence of defects

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SLIDE 5

Leakage Currents, Gas Generation and Case Deformation in Wets, Cont’d

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

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 Multiple (1650) transients did not cause case bulging likely due to H2 outdiffusion through tantalum case.  TC can result in irreversible lid deformation and excessive DCL.  To assure reliable operation in vacuum, HTS testing at 150 ºC for 1000 hours is recommended.  Glass seal protection in button case capacitors is less effective compared to the cylinder case parts.

y = 4.2153e0.036x 500 1000 1500 2000 2500 3000 50 100 150 200 displacement, um temperature, deg.C

HE3 SN5

20 40 60 80 100 120 140 160

100 200 300 400 500 600 700 800 100 200 300 400 500 600 temperature, deg.C displacement, um time, min

HE3 SN5

displ, um temp, C

Cracking of the seal after exposure to HT Bulging of the case

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SLIDE 6

ESR Degradation in MnO2 Capacitors

A report (https://nepp.nasa.gov/) includes analysis of environmental factors:

vacuum, high temperature storage, temperature cycling, moisture, and soldering.

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

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50 100 150 200 250 300 200 400 600 800 1000

ESR, mOhm time, hr

HTS 150C CWR29FC686KBGA, DC0703, ESR_max=275 mohm

20 40 60 80 100 120 200 400 600 800 1000 ESR, mohm time, hr

220uF 10V Mfr.B at 85C 85%RH

Most parametric ESR failures are due to insufficient margin to ESRlimit. MnO2 caps can withstand 1000 hr at 150 °C and at 85 °C/85% RH. AEC-Q200 requirements are much more severe compared to M55365. Compressive stresses after bake reduce delaminations and squeeze microcracks in cathode layers resulting in reduction of ESR. Swelling of MC and stress relaxation in moisture have opposite effects.

Examples of ESR variations during HTS and humidity testing

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SLIDE 7

Acceleration Factors for DCL Degradation and Failures

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

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A report (https://nepp.nasa.gov/) describes catastrophic and parametric failures in Ta capacitors, their mechanisms and AF.

 Analysis showed that 5.5 < B < 10.3, 1.42 < Ea <1.66 eV.  Parametric degradation is reversible and can be annealed at HT.  The mechanism of degradation is attributed to migration of

  • xygen vacancies in the dielectric with E ~1.1 eV.

1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 500 1000 1500 2000 current, A time, hr

6.8uF 25V Mfr.A at 125C, 16.6V

SN1 SN2 SN3 SN4 SN5 SN6 Failure

S im u la tio n

  • f T

T F s fo r 6 .8 u F 2 5 V c a p a c ito rs

tim e , h r cumulative probability, %

1 .E +2 1 .E +9 1 .E +3 1 .E +4 1 .E +5 1 .E +6 1 .E +7 1 .E +8 1 5 1 5 9 9 9

e x p e rim e n ta l d a ta c a lc u la tio n 1 2 5 C , 1 6 .6 V u s e c

  • n

d itio n s 5 5 C , 1 V

1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 init HALT 125C 35V bake 20hr 175C HALT 145C 25V bake 10hr 175C bake 30hr 175C bake 60hr 175C current@25V, 85C, A

6.8uF 25V capacitors

            − × = 1 exp VR V B AF

test V

              − × − =

2 1

1 1 exp T T k E AT

a T

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SLIDE 8

Kinetics of Moisture Sorption in MnO2 Capacitors

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

( ) ( )

            − − − × − + = τ

D

t t C C C t C exp 1 ) (

min max min

D d tD × = 6

2

S p d × × = ~ γ τ

  • 0.5

0.5 1.5 2.5 3.5 4.5 0.1 1 10 100 1000 ∆C/Cmin, % time, hr

Capacitors at 22C 85%RH after bake

CC1 calc CC6 calc MC1 calc

10 10.1 10.2 10.3 10.4 0.1 1 10 100

capacitance, uF time, hr

10uF MLCCs at 125C

CC1 MC1 E = 0.5 eV Ea =0.43eV 0.1 1 10 100 0.002 0.0025 0.003 0.0035 0.004 diffusion delay, hr 1/T, 1/K CC1 CC6 MC1

MC CC

Ea=0.36 eV Ea= 0.33 eV 1 10 100 1000 0.002 0.0025 0.003 0.0035 0.004 characteristic time, hr 1/T, 1/K CC1 CC6 MC1

MC CC

 Slugs in tantalum chip capacitors can be used as moisture sensors.

 A model for C-t

variations has been developed.  Bake-out times can be selected based on the characteristic times of the desorption process.

Moisture sorption can be characterized by two time constants

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SLIDE 9

Effect of Moisture on Degradation of Reverse Currents in MnO2 Capacitors

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

5 10 15 20 25 30 35 200 400 600 800 1000 1200 1400 1600 current, mA time, hr

194D at RBS 5V, 75C air vacuum

1 9 4 D e ffe c t o f h u m id ity a t 2 2 C a n d 4 V R B

s te a d y

  • s

ta te c u rre n t, m A cumulative probability, %

1 .E

  • 2

1 1 .E

  • 1

1 1 5 1 5 9 9 9

7 % R H 3 5 % R H 8 5 % R H

 Degradation under RB strongly depends on presence of moisture in environments and preconditioning.  Oxygen vacancies play important role in formation of protonic species.

x O i O

O H V O H + →  +

  • 2

2

  • →

 + +

O x O O

OH O V O H 2

2

RBS of 10uF 25V capacitors

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SLIDE 10

Polymer Capacitors

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

Report “Evaluation of 10V chip polymer tantalum capacitors…” (https://nepp.nasa.gov/) describes issues with low-voltage parts.

6.0E-8 A/hr 1.4E-07 A/hr 1.0E-07 A/hr 0.0E+0 5.0E-6 1.0E-5 1.5E-5 2.0E-5 2.5E-5 3.0E-5 20 40 60 80 100 120 140 160 current, A time, hr

T530 330uF at 125C 10V

SN2 SN7 SN9

1 10 100 1000 2500 5000 7500 10000 ESR, mohm time, hr

HTS at 100C T510 330uF T530 150uF T525 220uF

0.0E+0 5.0E-5 1.0E-4 1.5E-4 2.0E-4 2.5E-4 3.0E-4 3.5E-4 200 400 600 800 1000

current, A time, hr

220uF 10V at 85C, 10V

Parametric failures are likely to be major issues with polymer caps. QA system developed for MnO2 capacitors is not applicable. Unstable leakage currents that might be more significant in vacuum. Significant degradation of ESR during HTS.

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SLIDE 11

Polymer Capacitors, Cont’d

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

One of the most intriguing problems: anomalous transients after HTS  Moisture plays an important role in the mechanism of transients.  Anomalies in long-term transient currents might be due to changes in the trap system of Ta2O5.  More analysis necessary.

1.E-7 1.E-6 1.E-5 1.E-4 1.E-3 1.E-2 1.E-1

  • 80 -60 -40 -20

20 40 60 80 100 120 140 current, A temperature, deg.C

22uF 25V virgin and after HTS at 25V 100sec

virgin HTS

1.E-8 1.E-7 1.E-6 1.E-5 1.E-4 1.E-3 1.E-2 1.E-1

  • 80 -60 -40 -20

20 40 60 80 100 120 140 current, A temperature, deg.C

22uF 25V virgin and after 85C/85%RH at 25V 100sec

HUM virgin

1.E-7 1.E-6 1.E-5 1.E-4 1.E-3 1 10 100 1000 current, A time, sec

22uF 25V HTS at 125C

SNu init 70 SNu 23hr70 SNu 95hr70 SNu 311hr70 SNu 1007hr70 SNu 3009hr70 SNu 4012hr70 SNu 4996hr70

10 20 30 40 50 60 10 20 30 Voltage, V time, sec

22uF 25V capacitors after 120hr HTS 125C or 85C/85%RH

HTS 1mA HTS 2mA HTS 3mA HTS 4mA HTS 5mA HTS 6mA HTS 8mA HTS 10mA HTS 12mA HTS 14mA HUM 0.1mA

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SLIDE 12

Future Work on Tantalum Capacitors

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

 MnO2 chip capacitors.

  • Complete current tasks.
  • Reliability acceleration factors for automotive grade capacitors.

 Advanced wet capacitors.

  • Effect of HT storage on performance and reliability.
  • Evaluation of SMT wet tantalum capacitors.

 Polymer capacitors.

  • Degradation models for HTS and recommendations for S&Q.

 Super-capacitors for space application.

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SLIDE 13

Mechanical Properties of MLCCs

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

 Can mechanical characteristics predict robustness of MLCCs under soldering stresses?  Report that is available at https://nepp.nasa.gov/ includes:

  • Flexural Strength Testing of MLCCs.
  • Vickers Hardness Testing.
  • Indentation Fracture Test (IFT).

2

2 3 bd FL MOR =

AEC-Q200-003

C D R 3 5 B X 1 4 A K U S , 0 .1 u F , 5 V , s iz e 1 8 2 5 , M fr.C

M O R , M P a cumulative probability, %

4 4 1 1 5 1 5 9 9 9 in itia l a c tiv a te d ro s in flu x p

  • lis

h e d m

  • is

tu re : 1 6 h r, 8 5 % R H , 2 2 C m

  • is

tu re : 1 6 h r, 8 5 % R H , 2 2 C T S D 3 5 & m

  • is

tu re

1 N 5 N 2 .5 N 4 7 4 7 19 13 5 8 8

100 200 300 400 500 600 1206 1210 1808 1812 1825 2225 characteristic MOR, MPa case size

Effect of case size on MOR

PME BME

3

 Flexural strength method determines tensile strength at the surface.  No substantial difference between mechanical characteristics of BME and PME capacitors.  Smaller size MLCCs have greater strength – Benefits of BMEs.  Same size capacitors can be used for comparative analysis of the lots.  Variations of MOR values from lot to lot might exceed 50%.

2

2 3 bd FL MOR =

Modulus of rupture

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SLIDE 14

Vickers Hardness

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

 In-situ VH measurements are possible using MLCCs with relatively thick cover plates. P should be low so the depth of the

indentation is < 2x the thickness of the cover plate.

 No significant difference between PME and BME capacitors.  Improvements to reduce errors might allow for revealing differences in lots.

 Hardness is a resistance to indentation.

2

854 . 1 D P VH × =

V ic k e rs H a rd n e s s T e s t fo r P M E a n d B M E C a p a c ito rs

V H , G P a cumulative probability, %

7 1 2 8 9 1 1 1 1 5 1 5 9 9

BME PME 90% confidence

y = 191.65x

100 200 300 400 500 600 700 1 2 3 4 D^2, um^2 load, N

Vickers test, LT capacitors

SN1 SN2 SN3 SN4 SN5

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SLIDE 15

Indentation Fracture Test

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To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

 IFT can provide useful information regarding robustness of capacitors under soldering conditions, but additional analysis is necessary.  Mechanical testing might be useful for selecting robust parts for manual soldering, but more work is necessary to reduce errors and select criteria.  For critical applications a combination of assembly simulation and special testing might be recommended.  Fracture Toughness: the ability of a material to withstand stresses in the presence of cracks.  IFT technique is the most controversial.

            =

5 . 1 5 . _

c P VH E IFT

M R

ξ

20 40 60 80 100 120 140 160 180 1 2 3 4 5 c^1.5, (um)^1.5 load, N

PME_L capacitors

PME_L1, 1.7 PME-L2, 1.32 PME_L3, 1.49 PME_L4, 1.20

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 PN 1 PN 2 Kc, Mpa_m^0.5

PME_V capacitors

SN1 SN2 SN3 SN4 SN5

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SLIDE 16

Failures in BME Capacitors with Defects

16

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

 Migration of VO

++ is enhanced either by increased E, as in case of

thinning of the dielectric, or by increased µ, as in case of cracks.  Catastrophic failures occur when ΦB decreases to ΦBcr. For capacitors having small, micrometer-size defects ΦBcr is low so catastrophic failures are unlikely.  In the range of typical HALT conditions voltage increases the probability of catastrophic failures to a greater degree compared to temperature. This might result in errors in AFs.

Thermal run-away model

) , , (

2 B d d d

E T J r I Φ × × = π

θ

R T T V I dt dT C

d

− − × = ×

              Φ − = kT E kT E AT J

s B S 5 . 2 / 3

exp exp β µ

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SLIDE 17

17

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

Stretched exponential dependence of ΦB with time. In bulk: τV = 200 hr, (µV ~5×10-15 cm2/Vs) Along the crack: τc ~10 hr (µV ~10-13 cm2/Vs).

Model: accelerated migration of VO

++ along the cracks.

Simulations are in reasonable agreement with experimental data.

                        − − × ∆Φ = Φ

γ

τV

B B

t t exp 1 ) (

V d

V V

× × = µ τ

2

78 .

0.15 0.3 0.45 0.6 0.75 0.9 1.E-8 1.E-7 1.E-6 1.E-5 1.E-4 1.E-3 1.E-2 0.1 1 10 100 1000 ∆ΦB, eV current, A time, hr

I defect free I defect 1 I total def. 1 I defect 2 I total def. 2 DFB_def 1 =0.45eV DFB_def 2 =0.55eV DFB =0.1eV

∆ΦBcr =0.54eV

Effect of Cracking on Degradation of MLCCs at HT

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 0.1 1 10 100 1000 current, A time, hr virgin fractured

0.33uF/50V at life test cracks virgin Simulation of life testing

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SLIDE 18

Future Work on Ceramic Capacitors

 Evaluation of IDC capacitors used for FPGAs.  Comparative analysis of performance and reliability of BME and PME capacitors.

  • Breakdown voltages.
  • Analysis of failures in BME capacitors with defects.
  • Express testing to determine reliability acceleration factors for BME

capacitors.

  • Guidelines for selecting “auto” MLCCs for different project levels.

To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.

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