AlexanderTeverovsky DellServicesFederalGovernment,Inc.workperformedforNASAGoddardSpaceFlightCenter,Parts,Packaging,andAssemblyTechnologiesOffice,Code562 [email protected]NASA Electronic Parts and Packaging Program 1 Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
21
Embed
Reliability Issues with New Technology Wet Tantalum … 2013 WTC...Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Alexander TeverovskyDell Services Federal Government, Inc.
work performed for NASA Goddard Space Flight Center, Parts, Packaging, and Assembly Technologies Office, Code 562
1Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Specifics of wet tantalum capacitors (WTC). New designs. Reverse bias operation. Random vibration testing. Failure modes and
mechanisms. Conclusion and
recommendations. Guidelines for selection,
S&Q.
2Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
If Ta2O5 is damaged, anodic oxidation continues under normal, forward bias conditions resulting in oxide growth thus effectively eliminating the defect.
Self-healing contributes substantially to the reliability of WTC – is it a panacea?
3Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
0
1
2
3
4
5
6
7
0 25 50 75 100 125
VBR
/VR
rated voltage, V
Wet Tantalum Capacitors
M39006
advanced wet
0
1
2
3
4
5
6
7
0 25 50 75 100 125
VBR
/VR
rated voltage, V
Wet Tantalum Capacitors
M39006
advanced wet
Better performance of advanced WTC is achieved by reducing the thickness of the cathode layer, increasing the size of the slug, and using powder with a higher CV.
Different manufacturers are using different cathode materials, e.g.: activated C/NbO; Pd/Cu; RuO2.
Better performance does not come free. Reliability effect: reverse bias and mechanical stresses.
4Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
M39006 DWG93026
Robustness to RB is needed to get additional margin for testing and unforeseen events.
First tantalum capacitors in silver case had failures under low RB due to silver electrodepositing and dendrite growth.
The use of a tantalum case and oxidized sintered Ta powder allowed to improve substantially the robustness against RB.
New design WTC do not have protection against RB. 93026: RB < 1.5V and Q < 0.05C (?); 04005: no RB requirements.
Ta/Ta2O2 cathode
5Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Electrodeposition of cathode metals
In most cases the transfer charge is below the specified value of 0.05C.
Time to failure varies from part-to part substantially.
Failures might happen even at voltages as low as ~0.1V
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.001 0.01 0.1 1 10 100
curr
ent,
A
time, hr
93026 470uF 50V RBS 0.5V
SN6 8E-3SN7 1E-2SN8SN9 2.1E-2
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.001 0.01 0.1 1 10 100
curr
ent,
A
time, hr
93026 470uF 50V RBS 0.5V
SN6 8E-3SN7 1E-2SN8SN9 2.1E-2
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.01 0.1 1 10 100
curr
ent,
A
time, hr
93026 220uF 50V RBS 0.5V
SN30 1.8E-3
SN31 5.7E-4
SN32 1.8E-3
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.01 0.1 1 10 100
curr
ent,
A
time, hr
93026 220uF 50V RBS 0.5V
SN30 1.8E-3
SN31 5.7E-4
SN32 1.8E-3
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.01 0.1 1 10 100
curr
ent,
A
time, hr
93026 110uF 75V RBS 0.5V
SN10 1.6E-3
SN11 5.9E-2
SN12 8.1E-3
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0.01 0.1 1 10 100
curr
ent,
A
time, hr
93026 110uF 75V RBS 0.5V
SN10 1.6E-3
SN11 5.9E-2
SN12 8.1E-3
6Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Pd deposition on the surface of Ta2O5 reduces the barrier height and increases forward leakage currents.
Electrodeposition at defects prevents self-healing.Degradation is reversible only partially.
DWG#93026, 220uF 50V
Pd/Cu cathode coating
7Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
8Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Temperature and deformation of the case were measured using flexible sensors.
Strain increases linearly with time due to the pressure building up.Strain ~0.07% corresponds to a pressure of dozens of
atmospheres.
H2 generation at cathode:2e- + 2H2O(L) => H2(g) + 2OH-(aq)
y = 0.0027x
y = 0.0022x + 0.02
0
0.02
0.04
0.06
0.08
0.E+00 5.E+00 1.E+01 2.E+01 2.E+01
stra
in, %
time, hr
DWG93026 470uF 75V RBS 1mA
RBS 1mA 1
RBS 1mA 2
RBS 1mA 3
calc at V=10mm3y = 0.0027x
y = 0.0022x + 0.02
0
0.02
0.04
0.06
0.08
0.E+00 5.E+00 1.E+01 2.E+01 2.E+01
stra
in, %
time, hr
DWG93026 470uF 75V RBS 1mA
RBS 1mA 1
RBS 1mA 2
RBS 1mA 3
calc at V=10mm3
FztIn
VRTnP
hErP
9Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
SN19 failed after 100hr 2V RBS due to lead fell-off caused by electrolyte leak.
Pressure deforms the case, forces electrolyte above the Teflon bushing, and causes corrosion of the weld.
10Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
700
750
800
850
900
C_12
0Hz,
uF
DWG04005 980uF 60V 100hr RBS
700
750
800
850
900
C_12
0Hz,
uF
DWG04005 980uF 60V 100hr RBS
DWG04005 capacitors feature a sharp decrease in RB current and open circuit failure mode.
0
50
100
150
200
250
init 0.5V 0.75V 1V 1.25V 1.5V 2V
capa
cita
nce,
uF
04005 210uF125V 100hr RBS
SN650
SN638
SN535
SN657
0
50
100
150
200
250
init 0.5V 0.75V 1V 1.25V 1.5V 2V
capa
cita
nce,
uF
04005 210uF125V 100hr RBS
SN650
SN638
SN535
SN657
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
0.01 0.1 1 10 100
curre
nt, A
time, hr
04005 210uF 125V RBS 2V
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
0.01 0.1 1 10 100
curre
nt, A
time, hr
04005 210uF 125V RBS 2V
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
0.01 0.1 1 10 100
curre
nt, A
time, hr
DWG04005 870uF 60V RBS at 2V
A5A6A7A8
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
0.01 0.1 1 10 100
curre
nt, A
time, hr
DWG04005 870uF 60V RBS at 2V
A5A6A7A8
11Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Pressure starts building up after a few sec at 1V.
Pressure remains in the case when parts are unbiased and can cause electrolyte leak and corrosion.
DCL did not degrade after 100hr of 2V RBS; whereas C and ESR fail.
Strain ~3% => pressure up to 50 atm.1.E-02
1.E-01
1.E+00
1.E+01
1 10 100 1000 10000 100000
stra
in, %
time, sec
04005 I sens 870uF 60V
RBS 1V RBS 1.5VRBS 1.5V r RBS 2V
RBS 2V r
1.E-02
1.E-01
1.E+00
1.E+01
1 10 100 1000 10000 100000
stra
in, %
time, sec
04005 I sens 870uF 60V
RBS 1V RBS 1.5VRBS 1.5V r RBS 2V
RBS 2V r
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1 10 100 1000 10000
curr
ent@
50V,
A
time, sec
DWG04005 sens.I 870uF 60V
17.5hr 1V RBS
3hr 1.5V RBS
40hr 1.5V RBS
3hr 2V RBS
72hr 2V RBS
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1 10 100 1000 10000
curr
ent@
50V,
A
time, sec
DWG04005 sens.I 870uF 60V
17.5hr 1V RBS
3hr 1.5V RBS
40hr 1.5V RBS
3hr 2V RBS
72hr 2V RBS
12Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Strain accumulates with each cycle.Stabilization of pressure with time is
likely due to voltage drop below the threshold level.
FB currents do not degrade substantially.
Decrease of roll-off frequency with RBS
Failures in an open circuit mode.
13Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Internal pressure causes bulging.
Bulging strains the wire that fractures eventually. (max wire deformation ~ 0.25 mm; deformation of a clamped 20 mil membrane at 50 atm~0.23 mm)
The absence of a Teflon gasket facilitates electrolyte leakage.
Wire fracture and electrolyte leakage cause open circuit failures.
14Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Capacitors per DWG#93026 and #04005 are qualified to 20 g sin high frequency vibration only.
Sample size is not set (in some cases 2 samples only are tested).
Test conditions are not specific. Random vibration testing is not
required and is performed only if specified by the purchase order.
Random vibration test is more appropriate for space applications than HF sinusoidal vibration, and MARs for most projects require box-level random vibration testing at 14.1 Grms.
15Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04in
itz
20g
xy 2
0gz
34g
xy 3
4gz
54g
xy 5
4gz
65g
xy 6
5gz
65g
15m
xy 6
5g 1
5mz
65g
15m
rxy
65g
15m
r
curr
ent,
A
Mfr.B 470uF 50V DC0524
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04in
itz
20g
xy 2
0gz
34g
xy 3
4gz
54g
xy 5
4gz
65g
xy 6
5gz
65g
15m
xy 6
5g 1
5mz
65g
15m
rxy
65g
15m
r
curr
ent,
A
Mfr.B 470uF 50V DC0524
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
init
xy 2
0gxy
34g
xy 5
4gz
65g
15m
z 65
g 15
m r
z 65
g 15
m 3
z 65
g 15
m 4
z 65
g 15
m 5
z 65
g 15
m 6
z 65
g 15
m 7
z 65
g 15
m 8
z 65
g 15
m 9
x y 6
5g 1
5m 1
0
curr
ent,
A
Mfr.B 110uF 75V DC0810
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
init
xy 2
0gxy
34g
xy 5
4gz
65g
15m
z 65
g 15
m r
z 65
g 15
m 3
z 65
g 15
m 4
z 65
g 15
m 5
z 65
g 15
m 6
z 65
g 15
m 7
z 65
g 15
m 8
z 65
g 15
m 9
x y 6
5g 1
5m 1
0
curr
ent,
A
Mfr.B 110uF 75V DC08101.E-08
1.E-07
1.E-06
1.E-05
1.E-04
init z 20g xy 20g
z 34g xy 34g
z 54g xy 54g
curr
ent,
A
DWG93026 Mfr.A 470uF 75V
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
init z 20g xy 20g
z 34g xy 34g
z 54g xy 54g
curr
ent,
A
DWG93026 Mfr.A 470uF 75V
Different part types have failures from 20 to >65 Grms.
1.E-08
1.E-07
1.E-06
1.E-05
init z 20g
xy 20g
z 34g
xy 34g
z 54g
xy 54g
z 65g
xy 65g
curr
ent,
A
Mfr.B 220uF 50V DC0729
1.E-08
1.E-07
1.E-06
1.E-05
init z 20g
xy 20g
z 34g
xy 34g
z 54g
xy 54g
z 65g
xy 65g
curr
ent,
A
Mfr.B 220uF 50V DC0729
16Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
05
101520253035404550
0 250 500 750 1000
volta
ge, V
time, sec
DWG93026 470uF 75V at 10.7 rms g
SN6 SN7SN8 SN9SN10
05
101520253035404550
0 250 500 750 1000
volta
ge, V
time, sec
DWG93026 470uF 75V at 10.7 rms g
SN6 SN7SN8 SN9SN10
1.E‐07
1.E‐06
1.E‐05
1.E‐04
1.E‐03
1.E+1 1.E+2 1.E+3
curr
ent,
Atime, sec
DVG93026 470uF 75V after 10.7 rms g
SN6SN7SN8SN9SN10
1.E‐07
1.E‐06
1.E‐05
1.E‐04
1.E‐03
1.E+1 1.E+2 1.E+3
curr
ent,
Atime, sec
DVG93026 470uF 75V after 10.7 rms g
SN6SN7SN8SN9SN10
Some DWG#93026 parts can fail at vibration levels that are below MAR requirements.
17Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Several anomalies have been observed during thermal vacuum testing. However, at the end of the testing the unit operated normally.
Post-testing internal examinations revealed damaged sleeve, discoloration and charring of conformal coating around one of the WTCs.
The cracks were due to stresses caused by the building-up of gas pressure in the case and hydrogen embrittlement of tantalum at cold work areas.
18Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
Failures during vibration are likely caused by NbO and carbon particles penetrating inside the slug.
Under mechanical stresses these particles might create local stresses sufficient to cause damage to the dielectric and increase leakage current.
19Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
DWG#93026 and 04005 parts might fail at low-voltage (0.5V and less) RB conditions and random vibration as low as 10.7 Grms.
The probability of failure does not depend on rated voltage.RB and vibration can result in increased leakage currents, internal
gas pressure, case fractures, electrolyte leak, and corrosion.Parts with Pd-based cathode appeared to be more sensitive to RB,
whereas parts with Nb-based cathode are more sensitive to vibration.Manufacturers are working on new designs to improve reliability.Advance WTCs can self-heal, are resilient to environmental
stresses, but not to the degree of M39006 capacitors. To operate reliably, the robustness against mechanical stress (random vibration at 20 Grms) and RB (to 1.5V at 85C) should be verified.Guidelines for selection, S&Q and DPA of the WTC are suggested.
20Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.
21Presented by Alexander Teverovsky at the Components for Military & Space Electronics Conference & Exhibition (CMSE 2013), February 19-22, 2013, Los Angeles, CA, and published on nepp.nasa.gov.