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 Alexander.A.Teverovsky@nasa.gov To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology Workshop, Greenbelt, MD, June 2017.
List of Acronyms 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 To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology 2 Workshop, Greenbelt, MD, June 2017.
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 3 Workshop, Greenbelt, MD, June 2017.
Leakage Currents, Gas Generation and Case Deformation in Wets 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. WTCs with different types of Anomalies in leakage currents indicate internal seals presence of defects 1.E-03 DWG04005 240uF 125V 1.E-04 current, A 1.E-05 1.E-06 1.E-07 1.E+2 1.E+3 1.E+4 1.E+5 1.E+6 time, sec 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. To be presented by A.Teverovsky at the NASA Electronic Parts and Packaging (NEPP) Electronics Technology 4 Workshop, Greenbelt, MD, June 2017.
Leakage Currents, Gas Generation and Case Deformation in Wets, Cont’d Bulging of the case Cracking of the seal after exposure to HT HE3 SN5 HE3 SN5 3000 800 160 700 140 2500 displ, um 600 120 temperature, deg.C y = 4.2153e 0.036x displacement, um displacement, um temp, C 2000 500 100 1500 400 80 300 60 1000 Multiple (1650) transients did 200 40 500 100 20 not cause case bulging likely 0 0 0 0 50 100 150 200 0 100 200 300 400 500 600 temperature, deg.C time, min due to H 2 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. To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics 5 Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.
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. Examples of ESR variations during HTS and humidity testing 120 220uF 10V Mfr.B at 85C 85%RH HTS 150C CWR29FC686KBGA, 300 DC0703, ESR_max=275 mohm 100 250 80 200 ESR, mOhm ESR, mohm 60 150 40 100 20 50 0 0 0 200 400 600 800 1000 0 200 400 600 800 1000 time, hr time, hr Most parametric ESR failures are due to insufficient margin to ESR limit . 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. To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics 6 Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.
Acceleration Factors for DCL Degradation and Failures V A report (https://nepp.nasa.gov/) describes = × − test AF exp B 1 V VR catastrophic and parametric failures in Ta capacitors, their mechanisms and AF. E 1 1 = − × − a AT exp T k T T 1 2 S im u la tio n o f T T F s fo r 6 .8 u F 2 5 V c a p a c ito rs 1.E-03 6.8uF 25V capacitors 9 9 6.8uF 25V Mfr.A at 125C, 16.6V 1.E-04 9 0 1.E-04 current@25V, 85C, A u s e c o n d itio n s c a lc u la tio n 5 5 C , 1 0 V 1.E-05 1.E-05 5 0 cumulative probability, % current, A 1 2 5 C , 1 6 .6 V 1.E-06 1.E-06 1.E-07 1 0 e x p e rim e n ta l d a ta 5 1.E-07 SN1 SN2 1.E-08 SN3 SN4 SN5 SN6 1.E-09 Failure 1.E-08 init HALT bake HALT bake bake bake 1 1 .E +2 1 .E +3 1 .E +4 1 .E +5 1 .E +6 1 .E +7 1 .E +8 1 .E +9 0 500 1000 1500 2000 125C 20hr 145C 10hr 30hr 60hr tim e , h r 35V 175C 25V 175C 175C 175C time, hr Analysis showed that 5.5 < B < 10.3, 1.42 < E a <1.66 eV. Parametric degradation is reversible and can be annealed at HT. The mechanism of degradation is attributed to migration of oxygen vacancies in the dielectric with E ~1.1 eV. To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) Electronics 7 Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.
Kinetics of Moisture Sorption in MnO2 Capacitors Moisture sorption can be characterized by two time constants ( ) 2 d d − τ = ( ) = 6 t t = + − × − − t D ( ) 1 exp C t C C C D ~ γ × × τ × D p S min max min 10uF MLCCs at 125C Capacitors at 22C 85%RH after bake 10.4 Slugs in tantalum chip 4.5 CC1 CC1 10.3 capacitors can be used MC1 3.5 capacitance, uF calc ∆ C/Cmin, % CC6 2.5 10.2 calc as moisture sensors. MC1 1.5 calc A model for C-t 10.1 0.5 variations has been 10 -0.5 0.1 1 10 100 0.1 1 10 100 1000 time, hr time, hr developed. 1000 100 MC Bake-out times can be MC CC Ea=0.36 eV characteristic time, hr diffusion delay, hr 100 10 CC selected based on the E = 0.5 eV characteristic times of 10 1 CC1 CC1 Ea =0.43eV Ea= 0.33 eV CC6 CC6 the desorption process. MC1 MC1 1 0.1 0.002 0.0025 0.003 0.0035 0.004 0.002 0.0025 0.003 0.0035 0.004 1/T, 1/K 1/T, 1/K To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) 8 Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.
Effect of Moisture on Degradation of Reverse Currents in MnO2 Capacitors + • • → • + x H O V 2 H O RBS of 10uF 25V capacitors 2 O i O 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 • • • + + → x 9 9 H O V O 2 OH 2 O O O 9 0 7 % R H 5 0 cumulative probability, % 3 5 % R H 8 5 % R H 1 0 5 1 1 .E -2 1 .E -1 1 1 0 s te a d y -s ta te c u rre n t, m A 194D at RBS 5V, 75C 35 30 air Degradation under RB strongly 25 current, mA 20 depends on presence of moisture in 15 environments and preconditioning. 10 Oxygen vacancies play important 5 vacuum 0 role in formation of protonic species. 0 200 400 600 800 1000 1200 1400 1600 time, hr To be presented by Alexander Teverovsky at the 2017 NASA Electronics Parts and Packaging (NEPP) 9 Electronics Technology Workshop (ETW), NASA Goddard Space Flight Center, Greenbelt, MD, June 26-29, 2017.
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