Accelerated Aluminum Electrolytic Capacitor Life Testing: How to Pick the Most Reliable E-Cap in a Few Weeks Stephani Gulbrandsen

Transcription

1 Accelerated Aluminum Electrlytic Capacitr Life Testing: Hw t Pick the Mst Reliable E-Cap in a Few Weeks Stephani Gulbrandsen September 18, Virginia Manr Rd Ste 290, Beltsville MD

2 Overview E-caps Intrductin External Cnstructin Internal Cnstructin E-cap Failure Catastrphic Degradatin Wear-ut Criteria Testing Hw t Chse an E-cap Traditinal Trends in Traditinal Data Accelerated Calculatins Accelerated Critical Weight Lss Accelerated Calculatins Accelerated Wear-Out Failure Mde Benefits f Accelerated Apprach Accelerated Life Test Suppliers A & B Overview Suppliers A & B Rate f Weight Lss Suppliers A & B Critical Weight Lss Suppliers A & B Cmparisn Suppliers C & D Overview Suppliers C & D Rate f Weight Lss Suppliers C & D Critical Weight Lss Suppliers C & D Cmparisn Cnclusins Virginia Manr Rd Ste 290, Beltsville MD

3 Overview E-caps Intrductin External Cnstructin Internal Cnstructin E-cap Failure Catastrphic Degradatin Wear-ut Criteria Testing Hw t Chse an E-cap Traditinal Trends in Traditinal Data Accelerated Calculatins Accelerated Critical Weight Lss Accelerated Calculatins Accelerated Wear-Out Failure Mde Benefits f Accelerated Apprach Accelerated Life Test Suppliers A & B Overview Suppliers A & B Rate f Weight Lss Suppliers A & B Critical Weight Lss Suppliers A & B Cmparisn Suppliers C & D Overview Suppliers C & D Rate f Weight Lss Suppliers C & D Critical Weight Lss Suppliers C & D Cmparisn Cnclusins Virginia Manr Rd Ste 290, Beltsville MD

4 E-cap 3 E-cap 2 E-cap 1 E-caps Intrductin Datasheet lifetime Trad test (life)time Accel test time Industrial custmer cmmunicatin interface PCBA frm Mnic Inc. Digital media player PCBA frm Shenzhen Sinetech Electrnic C Ltd. Datasheet lifetime Trad test (life)time Accel test time Datasheet lifetime Trad test (life)time Accel test time Time Cmparisn f datasheet lifetime, traditinal test (life)time, and accelerated test time. Autmtive asset tracking PCBA frm Theta Engineering Inc Virginia Manr Rd Ste 290, Beltsville MD

5 E-caps External Cnstructin Ande (+) Al can Cathde (-) Rubber bung Vent E-cap external cnstructin. Radial lead Axial lead Screw terminal Snap in Fur types f E-cap leads Virginia Manr Rd Ste 290, Beltsville MD

6 Ande fil Al 2 O 3 dielectric Electrlyte Paper separatr Cathde fil E-caps Internal Cnstructin e - e - Internal sandwich structure f an E-cap. CT scan shwing the crimped seal between the can and the bung. Tp-dwn view f the rlled sandwich structure f an E-cap Virginia Manr Rd Ste 290, Beltsville MD

7 Overview Aluminum Electrlytic Capacitrs Intrductin External Cnstructin Internal Cnstructin E-cap Failure Catastrphic Degradatin Wear-ut Criteria Testing Hw t Chse an E-cap Traditinal Trends in Traditinal Data Accelerated Calculatins Accelerated Critical Weight Lss Accelerated Calculatins Accelerated Wear-Out Failure Mde Benefits f Accelerated Apprach Accelerated Life Test Suppliers A & B Overview Suppliers A & B Rate f Weight Lss Suppliers A & B Critical Weight Lss Suppliers A & B Cmparisn Suppliers C & D Overview Suppliers C & D Rate f Weight Lss Suppliers C & D Critical Weight Lss Suppliers C & D Cmparisn Cnclusins Virginia Manr Rd Ste 290, Beltsville MD

8 E-cap Failure Catastrphic Catastrphic failure Overstress Vltage Current Temperature Reverse plarity Bad electrlyte Catastrphic failure resulting in significant leakage f electrlyte frm E-cap vent. Catastrphic failure resulting in blwn capacitrs Virginia Manr Rd Ste 290, Beltsville MD

9 E-cap Failure Degradatin Degradatin failure Wear-ut Bad electrlyte Degradatin failure resulting in tented vent and ppped bung. Functining E-cap indicated by flat vent and in place bung Virginia Manr Rd Ste 290, Beltsville MD

10 E-cap Failure Wear-Out Apply ripple and bias e - e - e - PCB Heating f the capacitr frm applied ripple current causes evapratin f the electrlyte. e - PCB Internal pressure increase frm electrlyte evapratin facilitates electrlyte egress between the rubber bung and Al case Virginia Manr Rd Ste 290, Beltsville MD

11 Ande fil Al 2 O 3 dielectric Electrlyte Paper separatr Cathde fil Ande fil Al 2 O 3 dielectric Electrlyte Paper separatr Cathde fil % Increase ESR E-cap Failure Criteria Capacitance Change Dissipatin Factr* Leakage Current Within +/- 20% f initial value Nt mre than 200% f the specified value Initial specific value r less *Prprtinal t Equivalent Series Resistance (ESR). Electrlyte evapratin 200% Time Virginia Manr Rd Ste 290, Beltsville MD

12 Overview Aluminum Electrlytic Capacitrs Intrductin External Cnstructin Internal Cnstructin E-cap Failure Catastrphic Degradatin Wear-ut Criteria Testing Hw t Chse an E-cap Traditinal Trends in Traditinal Data Accelerated Calculatins Accelerated Critical Weight Lss Accelerated Calculatins Accelerated Wear-Out Failure Mde Benefits f Accelerated Apprach Accelerated Life Test Suppliers A & B Overview Suppliers A & B Rate f Weight Lss Suppliers A & B Critical Weight Lss Suppliers A & B Cmparisn Suppliers C & D Overview Suppliers C & D Rate f Weight Lss Suppliers C & D Critical Weight Lss Suppliers C & D Cmparisn Cnclusins Virginia Manr Rd Ste 290, Beltsville MD

13 Testing Hw t Chse an E-cap Supplier Vltage (V) Capacitance (uf) Max Operating Temperature Size Ripple (marms 85 C 120 Hz) V C 8 x W C 6.3 x X C 6.3 x Y C 6.3 x Z C 6.3 x Endurance (Lad) Life* *See datasheet fr infrmatin n test cnditins. Typically at rated temperature and vltage, but may r may nt apply ripple current. Datasheets fr example capacitrs stated nly max temperature with rated vltage were applied Virginia Manr Rd Ste 290, Beltsville MD

14 Testing Traditinal Apply rated ripple and bias at rated temperature. e - e - Oven and ripple current heating causes electrlyte evapratin. e - e - Turn ff electricity and cl t rm temperature. PCB PCB PCB N. Cntinue testing. Weigh. Yes. Testing is cmplete. Did ESR have a >200% increase frm the initial value? Measure ESR Electrical characterizatin. Weight: g Virginia Manr Rd Ste 290, Beltsville MD

15 Weight Lss % Increase ESR Testing Trends in Traditinal Data 800% 600% 400% 200% Time (hurs) Linear thrughut entire test lifetime f an E-cap ppulatin. Impact n Rate Variable f Weight Lss Ambient temperature Applied ripple current Heat dissipatin Space between bung and can Time (hurs) 4000 Expnential behavir that is relatively cnstant until apprach time t failure. Variable Electrlyte stability Initial ESR measurement Impact n Time t 200% Increase in ESR Virginia Manr Rd Ste 290, Beltsville MD

16 Weight Lss % Increase ESR Testing Accelerated Calculatins 800% 600% 400% Critical weight lss 200% Accelerated test lifetime Time (hurs) Weight Lss Critical weight lss 1. Critical weight lss at 200% increase in ESR is calculated using the ESR-Weight Lss curve 2. Rate f weight lss is extraplated t the critical weight lss and the crrespnding time is recrded as the accelerated test lifetime Virginia Manr Rd Ste 290, Beltsville MD

17 Testing Accelerated Critical Weight Lss Puncture a hle in the capacitr. Oven heating causes electrlyte evapratin. Turn ff heat and cl t rm temperature. N. Cntinue testing. Weigh. Yes. Testing is cmplete. Did ESR have a >200% increase frm the initial value? Measure ESR Electrical characterizatin. Weight: g Virginia Manr Rd Ste 290, Beltsville MD

18 Testing Accelerated Wear-Out Failure Mde Critical weight lss test Dried ut, ff white paper indicative f electrlyte evapratin. Grey paper indicative f electrlyte saturatin. As-received Virginia Manr Rd Ste 290, Beltsville MD

19 Testing Benefits f Accelerated Apprach 500 1,000 hurs f testing fr rate f weight lss and critical weight lss data Time is dependent n capacitr size Traditinal testing lasts 1,000 t >10,000 hurs with significant variability (0.5x 3x) when cmpared t datasheet lifetime Allws fr determinatin f relative reliability f capacitrs with cmparable electrical and physical characteristics under same test cnditins Useful fr determining which supplier is mre reliable fr the same applicatin Traditinal testing calculates actual time t failure fr a given ppulatin f capacitrs Virginia Manr Rd Ste 290, Beltsville MD

20 Overview Aluminum Electrlytic Capacitrs Intrductin External Cnstructin Internal Cnstructin E-cap Failure Catastrphic Degradatin Wear-ut Criteria Testing Hw t Chse an E-cap Traditinal Trends in Traditinal Data Accelerated Calculatins Accelerated Critical Weight Lss Accelerated Calculatins Accelerated Wear-Out Failure Mde Benefits f Accelerated Apprach Accelerated Life Test Suppliers A & B Overview Suppliers A & B Rate f Weight Lss Suppliers A & B Critical Weight Lss Suppliers A & B Cmparisn Suppliers C & D Overview Suppliers C & D Rate f Weight Lss Suppliers C & D Critical Weight Lss Suppliers C & D Cmparisn Cnclusins Virginia Manr Rd Ste 290, Beltsville MD

21 Accelerated Life Test Suppliers A & B Overview The accelerated test apprach was used t cmpare the behavir f the fllwing tw E-caps Supplier Capacitance (mf) Size (mm) Rated Lifetime (hrs) Vltage (V) A x , B x 40 >15, Rated Ripple Current (ma RMS) * Ripple applied at 120 Hz Virginia Manr Rd Ste 290, Beltsville MD

22 Accelerated Life Test Suppliers A & B Rate f Weight Lss 450 V, 68 mf Supplier A Rate f Weight Lss ½ Supplier B Rate f Weight Lss Supplier A capacitrs have a better seal between the can and bung Virginia Manr Rd Ste 290, Beltsville MD

23 Accelerated Life Test Suppliers A & B Critical Weight Lss 450 V, 68 mf Supplier A Critical Weight Lss Supplier B Critical Weight Lss Chemical stability f Supplier A and Supplier B electrlyte is cmparable Virginia Manr Rd Ste 290, Beltsville MD

24 Accelerated Life Test Suppliers A & B Cmparisn Accelerated life test results indicate that the Supplier A E-cap is mre reliable than Supplier B This is ppsite what the datasheet lifetimes suggest Supplier A Supplier B Virginia Manr Rd Ste 290, Beltsville MD

25 Accelerated Life Test Suppliers C & D Overview The accelerated test apprach was used t cmpare the behavir f the fllwing E-caps Supplier Capacitance (mf) Size (mm) Rated Lifetime (hrs) Vltage (V) C x 20 10, D x 20 5, Rated Ripple Current (ma RMS) * Ripple applied at 120 Hz Virginia Manr Rd Ste 290, Beltsville MD

26 Accelerated Life Test Suppliers C & D Rate f Weight Lss 450 V, 2.2 mf Supplier C Rate f Weight Lss 2 Supplier D Rate f Weight Lss Supplier C capacitrs have a wrse seal between the Al can and bung Virginia Manr Rd Ste 290, Beltsville MD

27 Accelerated Life Test Suppliers C & D Critical Weight Lss 450 V, 2.2 mf Supplier C Critical Weight Lss 2.5 Supplier D Critical Weight Lss Supplier C capacitrs have a mre chemically stable electrlyte Virginia Manr Rd Ste 290, Beltsville MD

28 Accelerated Life Test Suppliers C & D Cmparisn Accelerated life test results indicate that the Supplier C E-cap is mre reliable than Supplier D This supprts what the datasheet lifetimes suggest Supplier C Supplier D Virginia Manr Rd Ste 290, Beltsville MD

29 Overview Aluminum Electrlytic Capacitrs Intrductin External Cnstructin Internal Cnstructin E-cap Failure Catastrphic Degradatin Wear-ut Criteria Testing Hw t Chse an E-cap Traditinal Trends in Traditinal Data Accelerated Calculatins Accelerated Critical Weight Lss Accelerated Calculatins Accelerated Wear-Out Failure Mde Benefits f Accelerated Apprach Accelerated Life Test Suppliers A & B Overview Suppliers A & B Rate f Weight Lss Suppliers A & B Critical Weight Lss Suppliers A & B Cmparisn Suppliers C & D Overview Suppliers C & D Rate f Weight Lss Suppliers C & D Critical Weight Lss Suppliers C & D Cmparisn Cnclusins Virginia Manr Rd Ste 290, Beltsville MD

30 Cnclusins The Al ECap accelerated life test apprach is an effective way t cmpare the reliability f the same capacitrs frm different manufacturers under applied test cnditins Test results indicated that datasheet lifetime values can be inaccurate when cmpared t the reliability test results Virginia Manr Rd Ste 290, Beltsville MD

31 Questins??? Stephani Gulbrandsen is a Member f the Technical Staff at DfR Slutins. Prir t this she cmpleted a master s degree at Gergia Tech in Materials Science and Engineering. Stephani has used her research experience t develp accelerated electrlytic capacitr testing. In her free time she enjys cking and spending time with her family Virginia Manr Rd Ste 290, Beltsville MD