TANTALUM Tantalum vs. Ceramic capacitor 1 DESIGN OPPORTUNITIES TANTALUM Why Not Ceramics ? Ceramic Capacitors Issues: • Capacitance drops due to increasing DC BIAS • Capacitance degradation over temperature range • Capacitance goes down due to small AC signal (20-30%) • Loosing capacitance during life time • Piezoeffect mechanism • Mechanical weakness Degradation of capacitance can lead to wrong performance and instability of an amplifier 2 DESIGN OPPORTUNITIES TANTALUM STABLE PARAMETERS Why Not Ceramics ? Capacitance dependent to BIAS and temperature may degrade smoothing capability Tantalum TAJ A10uF/6.3V CERAMIC A10uF/6.3V X7R, X5R Graph of capacitance stability Graph of capacitance stability 12 12 11 11 10 9 9 Capacitance (uF) 8 7 6 5 4 3 2 1 0 8 7 6 5 4 3 2 110 120 70 60 Temperature(°C) 2 90 (V) 40 4 5 DC bias voltage 50 0 10 20 30 1 100 7 6 2 80 110 120 90 70 3 100 Temperature(°C) 80 60 40 1 0 50 10 20 30 Capacitance (uF) 10 7 6 1 0 3 4 5 DC bias voltage (V) 3 DESIGN OPPORTUNITIES TANTALUM Temperature Characteristic Typic al Capac itanc e vs . Te mpe rature 15% Capacitance [%] Stable Capacitance +/- 5% in temperature range –55/+85°C = Stable Filtering even with Operating Temperature Variation 20% 10% 5% 0% -5% OxiCapTM Tantalum -10% -15% -20% -50 -25 0 25 50 75 100 125 Te mpe rature [°C] Cap Typical ESR Vers us Temperature 100% ESR change [%] 80% 60% 40% 20% 0% -20%-50 ESR drop with Temperature - MnO2 conductivity driven as tantalum = Better Filtering at Higher Operating Temperatures ESR compare to ESR@25C specification OxiCap Tantalum -25 0 25 50 -40% -60% Temperature [°C] 75 100 125 4 2. Stable capacitance over applied AC signal TANTALUM Why Not Ceramics ? Degradation of capacitance can lead to wrong performance and instability of the amplifier CERAMIC A10uF/6.3V X7R, X5R Tantalum TAJ A10uF/6.3V AC s ig nal ve rs us c apac itanc e AC s ig nal ve rs us c apac itanc e 4 10.55 3.95 10.5 3.9 Capacitance (uF) Capacitance (uF) IN 10.6 10.45 10.4 10.35 10.3 3.85 3.8 3.75 3.7 10.25 3.65 10.2 3.6 0 0.2 0.4 0.6 0.8 AC sig na l le ve l (V) 1 0 0.2 0.4 0.6 0.8 AC sig na l le ve l (V) 1 Measured at 5V application voltage The capacitance of ceramic capacitor drops down with applied small AC signal voltage therefore the amplifier cannot secure stable performance 5 DESIGN OPPORTUNITIES Barium titanate used in ceramic capacitors is permitive material and exhibits PIEZO EFFECT = X5R,X7R,Y5V dielectrics can work as a small microphone or speaker and thus degrade signal purity to create additional noise Oscilloscope CERAMIC Voltage (uV) Why Not Ceramics ? TANTALUM CLEAR FILTERING Output level - 1000Hz input sinus signal MLC capacitor 10uF/16V (Y5V) 300 200 100 0 -100 -200 -300 time (ms) TANTALUM Output level - 1000Hz input sinus signal Tantalum capacitor 10uF/10V Ceramic A10uF/6.3V Tantalum A10uF/6.3V Mechanical and/or Electrical Stress Voltage (uV) ~G 300 200 100 0 -100 -200 -300 time (ms) 6 0 0.5 Supplier 5- Standard Aluminum 100/6.3 Supplier 5- Standard Aluminum 100/16 Supplier 4- Aluminum polymer 150/6.3 AVX- Niobium Oxide Y 100/6.3 0 AVX- Niobium Oxide C 100/6.3 6 AVX- Niobium Oxide B 22/6.3 10 AVX- Niobium Oxide A 10/6.3 12 Supplier 3- Tantalum 150/6.3 18 AVX- tantalum Y 100/6.3 Technology assessment AVX- tantalum C 100/6.3 14 Vo ltag e (mV) 16 AVX- tantalum B 22/6.3 AVX- tantalum A 10/6.3 Supplier 1- Ceramic A 4.7/6.3 Supplier 1- Ceramic A 4.7/10 Supplier 1- Ceramic A 4.7/16 Supplier 1- Ceramic A 10/6.3 Supplier 1- Ceramic A 10/16 Supplier 1- Ceramic A 10/16 Supplier 1- Ceramic B 22/10 Supplier 1- Ceramic A 22/6.3 Supplier 1- Ceramic B 100/6.3 Supplier 2- Ceramic A 10/25 Supplier 2- Ceramic B 100/6.3 Supplier 1- Ceramic B 22/10 Supplier 1- Ceramic A 10/16 Vrms [mV] Piezoeffect measurement 1 TANTALUM Transient measurement 20 S upplier 1- MLCC A10uF/6.3V X5R 15 AVX- OxiCapTM A10uF/6.3V 10 AVX- Tantalum A10uF/6.3V 5 0 -5 -10 8 -15 -20 Time (ms) 1.5 2 2.5 4 2 Compared technology Ceramic Tantalum Niobium Oxide Aluminium 7 DESIGN OPPORTUNITIES Why Not Ceramics ? TANTALUM CLEAR FILTERING Example of Picture Density what could happen when Tantalum or Ceramic capacitors are used as a coupling components in VIDEO (CCD) applications. with Tantalum capacitor with Ceramic capacitor 8 DESIGN OPPORTUNITIES TANTALUM RELIABILITY Why Not Ceramics ? Based on MILITARY SPECIFICATION ! MIL-HDBK-217F higher failure rate of ceramic than tantalum capacitors for derating ≧ 30% Absolute failure rate Relative failure rate FIT [parts/BPcHr] CERAMIC CERAMI C TANTALUM 60x 10x 20x applied / rated voltage 30x TAN TALUM Temperature [°C] Ua/Ur [-] Assumptions: temperature C = 10µF; standard failure rate 1%/kPcHr; Ground-Benign environment; circuit resistance < 0.1Ω/V 9 4. Mechanical robustness against cracking TANTALUM Why Not Ceramics ? High CV Ceramic Issues During Drop Test Mechanical Stress Sensitivity Reliability on High CV 10 Legislation Technology Driving Why Not Ceramics ? TANTALUM Non-Smoke Initiative “electronic devices should not emit smoke” - environmental law in Japan, USA under preparation - after dielectric breakdown capacitors changing to SC (smoke & burn) •47 & 100 nF 50V 0805 X7R (MLCC) in automotive application Even MLCC can burn 11 DESIGN OPPORTUNITIES TANTALUM POWER SUPPLIES Why Tantalums are the Best Choice for Most of the Output Capacitors ? Source: Technical Paper, Linear Technology stabilization time 22uF ceramic 22uF cer. + 0.5 Ohm AVX ta TPS 22uF/25V power up 22uF cer + 30V TVS 47uF leaded Aluminium Aluminium - good for transient however too high ESR for smoothing Ceramic – good for high freq. smoothing but risk of transient & oscillation Tantalum – good compromise, relatively easy for reliable DC/DC design 12 DESIGN OPPORTUNITIES Why Not Ceramics ? TANTALUM STABLE PARAMETERS One range lower ESR not always advantage 4.7uF/10V Tantalum OxiCap potential “For stable operation over the full operating range, use a 4.7µF (1µF min) low-cost, high-ESR small size tantalum capacitor with ESR > 0.5Ω” Source: MAX8885 datasheet Power Supply converter for cellular phone Maxim 8885 13 TANTALUM Typical application Suitability for 22uF and higher capacitance of Tantalum and OxiCapTM capacitors Wide range stability of the output voltage is secured by capacitor with capacitance 22uF or over and ESR level in range from 100mOhms to 1Ohm. However, output current higher then 200mAms requires wider range of ESR (from 50mOhms to 5Ohms) 14 DESIGN OPPORTUNITIES TANTALUM DIGITAL CAMERAS How to achieve clear video filtering ? …combine ceramic and tantalum capacitors… INCORRECTLY PROCESSED IMAGE-FREQUENCY INFORMATION CAN DISTORT DISPLAYS GENERATED FROM DIGITAL-VIDEO SOURCES. BEFORE YOU DESIGN YOUR NEXT DIGITAL-VIDEO SYSTEM, TAKE SOME TIME TO INVESTIGATE VIDEORECONSTRUCTION-FILTER DESIGN AND TRADE-OFFS IN OVERSAMPLING. 0.001 and 0.1uF ceramic 10uF tantalum buffer/filter for standard-video output with encoder with four-times oversampling and a filter cutoff frequency of 12 MHz. Source: Technical Paper, Analog Devices 15 DESIGN OPPORTUNITIES TANTALUM NOTEBOOKS Dell Cost Saving VDC= 2.59V, VAC(pk-pk)=95mV 1x Ceramic B 22uF/10V, 5mOhm AC e le me nt o f s ig nal 60 Vo lta g e (mV) 40 20 0 -20 -40 -60 0 20 40 60 80 100 Time (us) 1x OxiCapTM B 47uF/4V, VDC= 2.59V, VAC(pk-pk)=46.7mV VDC=2.59V, VAC(pk-pk)=47.1mV AC e le me nt o f s ig nal AC e le me nt o f s ig nal 60 60 Vo lta g e (m V) 20 0 -20 40 Vo lta g e (mV) C1 OxiCapTM B 47u/4V + 40 20 0 -20 -40 0 -40 -60 C2 ceramic L 470nF/10V -60 0 20 40 60 80 100 Time (us) 1x OxiCapTM B 47uF/4V COST SAVING & THE SAME PERFORMANCE 1x Ceramic L 1uF/10V 0 20 40 60 80 100 Time (us) 16 DESIGN OPPORTUNITIES TANTALUM PC MOTHERBOARDS PC Motherboards Get More Powerfull - total capacitors count per MB increased by 25% in 2002 - cap count >10uF increased from 30 to more than 100 (by 230%) - in 2002 tantalum caps dominated 10-22uF range (40 per board) compare to 2001 where aluminium capacitors > 10uF were used 2002 model 2001 model 120 120 Aluminium 149 Tantalum 100 Aluminium (Polymer) Tantalum (Polymer) Aluminium Tantalum MLCC 363 100 MLCC Pcs. Pcs. 80 60 60 40 40 20 20 0 80 0 101 102 103 104 105 225 475 106 226 476 107 227 337 477 108 Capacitance 101 102 103 104 105 225 475 106 226 476 107 227 337 477 567 108 228 Capacitance State of affairs with installation of capacitors on PC mother boards Source: AEI, Murata 17 TANTALUM Tantalum and Hi CV Ceramic comparison Pa ra me te r Ta nta lum ca pa cito r Ce ra mic Vo lume tric e fficie ncy X Re lia bility X ES R/ES L DC bia s ca pa cita nce sta bility X Te mpe ra ture sta bility X Pie zo e ffe ct X Lo w fre que ncy filte ring X Hig h fre que ncy filte ring Po la rity o rie nta tio n No cra cking X ca pa cito r X X X X - positive features 18