2015 nepp tasks update for ceramic and tantalum capacitors · 2015 nepp tasks update for ceramic...
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2015 NEPP Tasks Update for Ceramic and Tantalum Capacitors
Alexander TeverovskyAS&D, Inc.
Work performed for Parts, Packaging, and Assembly Technologies Office,
NASA GSFC, Code [email protected]
NASA Electronic Parts and Packaging (NEPP) Program
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
https://ntrs.nasa.gov/search.jsp?R=20170000475 2020-04-19T09:29:22+00:00Z
List of Acronyms
AF acceleration factor IM Infant mortalityBI burning-in JAXA Japan Aerospace Exploration Agency
BME base metal electrode MLCC multilayer ceramic capacitorDCL direct current leakage PHS polymer hermetically sealedESR Equivalent series resistance PME precious metal electrodeFB ferrite beads PV Prokopowicz-VaskasFR failure rate QA quality assurance
HALT highly accelerated life testing RVT random vibration testingHSD hot solder dip S&Q screening and qualificationHT High temperature VR rated voltage
HTS high temperature storage
2Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Reasons for NEPP Tasks on Capacitors
Capacitors constitute the majority of elements in electronic systems.
New technologies and designs appear with increasing speed. There is a need for optimization of S&Q procedures and setting adequate requirements.
Physics behind degradation and failure processes needs better understanding.
Capacitors exhibit both, infant mortality and wear-out failures, and can be used as models to refine quality assurance approaches for variety of space components.
3Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Outline Update on tantalum capacitors. Use of ferrite beads as surge current limiters. Polymer capacitors. Random vibration testing of advanced wet capacitors. Future work.
Update on ceramic capacitors. Effect of cracking on degradation of MLCCs at high
temperatures. Can we use automotive industry capacitors? Future work.
4Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Ferrite Chip Beads as Surge Current Limiters
5
Contrary to inductors, FBs at high frequencies work like resistors and dissipate power in the form of heat.
NEPP report contains (https://nepp.nasa.gov/): Analysis of requirements of DLA DWG#03024 for hi-rel chips; Results of testing of 12 types of FB; Data on the specific features of FBs; Evaluation of the robustness of FB to soldering stresses; Behavior of FBs under multiple high current spikes. Recommendations for reliability assurance of tantalum
capacitors operating under surge current conditions. Conclusion: Due to decrease of impedance with frequency and current,
the effective resistance remains substantially below the value that is required to limit surge in tantalum capacitors (from 1 to 5 Ohm). Recommendations on current derating are available at
https://nepp.nasa.gov/.
05
1015202530354045
-10 10 30 50 70 90
curre
nt, A
time, us
Effect of ferrite beads on surge currents
15uF 10V at 22V surge
same with FB 03024-021
0.16 ohm
0.11 ohm
0
30
60
90
120
150
180
0 10 20 30
curre
nt s
pike
, Avoltage, V
BLM18PG181SNID, 0603, 180ohm, 90mohm, 1.5A
no FBSN1SN2SN3SN4SN5SN6failures
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Polymer Tantalum CapacitorsA report on evaluation of PHS capacitors manufactured
per DLA LAM DWG#13030 (https://nepp.nasa.gov/):Literature review; analysis of requirements; characteristics, including thermal resistance; behavior of DCL under forward and reverse bias, recommendations.
Specific feature: operation of polymer capacitors requires certain amount of moisture in the case. What happens if cases dry out?
6
Variations of capacitance, ESR, and DCL with time of HTS
20
40
60
80
100
120
0 200 400 600 800 1000
capa
cita
nce,
uF
time, hr
PHS 100uF 60V during HTS at 150C
hermetic
non-hermetic
0
0.2
0.4
0.6
0.8
1
0 200 400 600 800 1000
ESR,
Ohm
time, hr
PHS 100uF 60V during HTS at 150C
hermetic
non-hermetic
1.E-08
1.E-07
1.E-06
0 200 400 600 800 1000
DC
L_10
00 s
ec, A
time, hr
PHS14 100uF 60V
pol SN7 pol SN8pol SN9 pol SN10pol SN11 dep SN7dep SN8 dep SN9dep SN10 dep SN11
non-hermetic
PHS can survive 1000 hr storage at 150°C without degradation. Non-hermetic parts degraded due to a substantial decrease in
capacitance and increase in ESR caused likely by increasing resistance of the polymer.
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Recommendations for Use of PHS
7
PHS capacitors have lower weight and ESR compared to similar case size wet tantalum capacitors and their application in power lines can assure better filtering and lower ripple currents.
Polymer capacitors would mostly benefit low-temperature applications (below 0°C) or systems where a cold start-up is required. However, additional application-specific testing are required if the parts are to be used at T < -55°C.
Self-healing capability of PHS is much worse than wet capacitors and flaws in the dielectric that might be forgiven in wet capacitors might cause catastrophic failures in PHS. This requires a close attention to the results of S&Q, specifically, to measurements of leakage currents through the testing.
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Random Vibration Testing
8
Report is available at https://nepp.nasa.gov/ Problems in assurance robustness of capacitors
under RVT have a long history. Larger anode size increases the stress during RVT. Existing requirements and practice: MIL-PRF-39006: 1.5hr in 3 directions; 30 min
monitoring every 0.5 msec “to determine intermittent open-circuiting or short-circuiting”.
Test techniques and failure criteria are not specified allowing different test labs to carry out testing differently, e.g limiting resistors from ohms to dozens of kohms, and failure criteria vary from 5% to 90% of VR.
Different set-ups have different sensitivity to short-circuiting. Different failure criteria cause inconsistency in test results. A single scintillation event is sufficient to cause lot failure.
Some test labs assume this level of spiking is acceptable
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
RVT: Step Stress Testing
9
0.0E+00
5.0E-06
1.0E-05
1.5E-05
2.0E-05
0 200 400 600 800 1000 1200
curre
nt, A
time, sec
680uF 50V Mfr.C at 34.02g rms
SN1
SN2
SN3
SN4
SN5
0.0E+00
5.0E-06
1.0E-05
1.5E-05
2.0E-05
0 200 400 600 800 1000 1200
curre
nt, A
time, sec
680uF 50V Mfr.C at 53.44g rms
SN1
SN2
SN3
SN4
SN5
Example of a part passing RVT at 34 g rms and failing at 53.44 g rms
0.0E+00
2.0E-06
4.0E-06
6.0E-06
8.0E-06
1.0E-05
0 200 400 600 800 1000 1200
curre
nt, A
time, sec
DWG#93026 470uF 75V Mfr.Aat 10.76g rms
SN1
SN2
SN3
SN4
0.0E+00
2.0E-06
4.0E-06
6.0E-06
8.0E-06
1.0E-05
0 200 400 600 800 1000 1200
curre
nt, A
time, sec
DWG#93026 470uF 75V Mfr.Aat 19.64g rms
Did this part fail at 10.76 g rms, at 19.64 g rms?
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
RVT: Post-testing Leakage Currents
10
Leakage currents were monitored with time after RVT.
0.0E+00
1.0E-05
2.0E-05
3.0E-05
4.0E-05
5.0E-05
0 200 400 600 800 1000 1200
curre
nt, A
time, sec
560uF 25V Mfr.A at 53.79 g rms
SN1SN2SN3SN4
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E+1 1.E+2 1.E+3 1.E+4 1.E+5
curre
nt, A
time, sec
560uF 25V Mfr.A at RT, 25V
initial
af ter RVT
Currents during RVT Currents after RVT
Spiking during RVT might not result in DCL failures after the testing.560 µF 25 V capacitors passed HALT after RVT at 53.8 g rms.Parts with excessive currents are recovering with time under bias.1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-3 1.E-2 1.E-1 1.E+0 1.E+1 1.E+2
curre
nt@
75V,
A
time, hr
470uF 75V Mfr.A after RVT
SN1SN2SN3SN4SN5
0.0E+00
2.0E-06
4.0E-06
6.0E-06
8.0E-06
1.0E-05
0 200 400 600 800 1000 1200
curre
nt, A
time, sec
470uF 75V Mfr.A at 34.02g rms
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
RVT: Recommendations
11
Different tests for different risk levels.
Each lot should be tested. Typical testing: 19.6 g rms , 6 samples. 15 min in each direction. DCL is monitored (10k, 0.1sec
sampling). Criterion I: Isp > 3DCL(5) = 3×I300
Criterion II: Q > Qcr
Criterion III: I300_RVT < 1.25×I300_init
Lots older than 5 years should be retested.
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Future Work on Tantalum Capacitors
MnO2 chip capacitors. Rapid assessment of reliability acceleration factors. Degradation during long-term operation under reverse bias.
Advanced wet capacitors. Analysis of DCL(T, V, t), breakdown processes, gas generation, and
requirements for S&Q. Effect of HT storage on performance and reliability.
Polymer capacitors. Evaluation of chip tantalum capacitors and requirements for S&Q. Evaluation of new types of hermetically sealed capacitors.
Solid electrolyte super-capacitors for space application.
12Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Life Testing of MLCCs with Cracks
13
Cracking does not affect IR at 125 °C but facilitates degradation of leakage currents.
In the presence of cracks, currents in BMEs start increasing after a few hours of testing, but stabilize with time.
Degradation in PMEs with cracks occurs at much higher levels of stress, and contrary to BMEs results in instantaneous short circuit failures (due to HT silver migration?).
Contrary to humid environments, at high temperatures, BMEs with cracks degrade faster than PMEs (degradation vs. catastrophic failures).
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E+2 1.E+3 1.E+4 1.E+5
curre
nt, A
time, sec
CDR 1825 with cracks at125C 200V
Mfr.V
Mfr.C
1.E-07
1.E-06
1.E-05
1.E-04
1.E+2 1.E+3 1.E+4 1.E+5
curre
nt, A
time, sec
BME 0.33uF 50V 1210 with cracks at 125C 100V
Mfr.C
Mfr.A
Typical variations of currents during HALT
Reference parts
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Can we Use “AUTO” Capacitors?Benefits of using “auto” grade
capacitors are obvious.Adaptation of “auto” components
should start after ~5 years on the market.
For MLCCs we are ~10 years late.Major QA problems: Lead-free terminations (Sn whiskers). “Insufficient screening” (no BI) Lack of long-term reliability data.
Issues to discuss: Acceptable measures to mitigate
whiskering. Why do we need burning-in? What long-term testing tells us?
14
WhiskeringCan be mitigated by using Sn/Pb
solder, conformal coating, etc. JAXA uses HSD to replace Sn on
“auto” BMEs with Sn/Pb followed by additional screening.
0201, smartphones
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Is Burning-In Necessary?QA wisdom: “Reliability should be designed into product and processes,
but not screened out by testing”. In practice, we require that parts for space applications go through BI. The purpose of BI is to remove IM failures from the lot.
15
)(1)()()(
BI
BIBI
tAFFtAFFtAFtFtF
×−×−×+
=
−−=
β
ηttF~
exp1)~(
Probability of failure after BI for tBI hrs
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
1.E+0 1.E+1 1.E+2 1.E+3 1.E+4 1.E+5 1.E+6
prob
abilit
y of
failu
re
time, hr
Effect of BI, eta=1E6 hr and AF=1000
b=0.2 no BIb=1 no BIb=3 no BIb=0.2 BI_240b=1 BI_240b=3 BI_240
BI is useless if lots do not have IM or their proportion is below a certain level.
BI reduces useful life for lots susceptible to wear-out. Burning-In might be not necessary.
β < 1 => IM failuresβ = 1 => random failuresβ > 1 => wear-out failures
1
)(−
=
β
ηηβλ tt
Weibull distribution determines type of failures
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
What Results of Life Testing Mean?Still, FR can be estimated if: There is no significant lot-to-lot variations.
(Verification of consistency of quality is built into MIL system. There is a greater portion of “trust/relationship” in “auto” industry.) Same mechanisms at life test and normal
conditions.(not always so, e.g. moisture, cracking/soldering) Failures are random (β = 1).
(probably never happens; instead: λ= const < FRspec). Accelerating factors are known.
(Is not true in most cases.)
16
tNAFn
×××
+=
52 1012
)22,(αχλ
Field failures are typically due to conditions that are not simulated by life testing.Without AF, comparison of life tests (PME vs. BME) is not correct.Emphasizing importance of 10 khr HALT can mislead
manufacturers. The focus should be on consistency of quality.
PME BME1000 hr 10,000 hr 1000 hr 10,000 hr
failures 0 1 0 1PV const. nV= 3, Ea= 0.8eV nV= 4, Ea= 1.1eV
AF 14,404 439,199FR 2.9E-04 6.4E-05 9.5E-06 2.1E-06
FR( in %/1000hr at 60% conf) at 50ºC, 0.5VR based on life testing of 22 samples
Life testing is typically a qualification (qualitative), not a reliability (quantitative) test.
Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.
Future Work on Ceramic Capacitors Cracking-related problems. Develop mechanical tests (board flex and strength) and assess their
effectiveness for quality assurance. Analysis of cracking on degradation and failures at high temperatures. Develop recommendations to mitigate risks of manual soldering/rework.
Comparative analysis of performance and reliability of BME and PME capacitors. Breakdown voltages, leakage currents and insulation resistance. 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.
Specifics of QA and attachment for small-size MLCCs. Analysis of requirements for stacking capacitors.
17Deliverable to NASA Electronic Parts and Packaging (NEPP) Program to be published on nepp.nasa.gov originally presented by Alexander Teverovsky at the NASA Electronic Parts and Packaging Program (NEPP) Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center in Greenbelt, MD, June 23-26, 2015.