Hardware Developers Didactic Galactic 0xb: Capacitors

Click here to load reader

  • date post

    16-Feb-2017
  • Category

    Technology

  • view

    9.517
  • download

    0

Embed Size (px)

Transcript of Hardware Developers Didactic Galactic 0xb: Capacitors

  • 1

    Theyre JUST capacitors?

    James LewisMarketing [email protected]

    @baldengineer

  • 2 Different materials make different capacitors

    Electrode Plates Dielectric

    Basic Capacitor

    C = 0KA(n1)d

  • 3

    Topic List

    Ceramics Why they lose capacitance

    Aluminum Why they dont last forever

    Tantalum Why are they are safe to use

    Supercapacitors Why they are called super

    We need a context

  • 4

    Capacitors should be voltage derated 50%

    True Or False

    It Depends

  • 5

    Ceramics

  • 6

    Multilayer Ceramic Capacitor (MLCC)Typical Construction

    Ceramic Dielectric

    Electrode (Ni for BME, Ag/Pd for PME)

    Termination (Cu for BME, Ag for PME)

    Finish(Plated Sn)

    Barrier Layer (Plated Ni)

    +-

    Capacitances in parallel are additive

    CT=C1+C2+C3+.Cn

    C = 0KA(n1)dMax Capacitance is limited by larger layers

  • 7

    Relative Capacitance vs. TemperatureTemperature Coefficients

    C0G (NP0)

    Temperature

    K

    Mag

    nitu

    de

    X7R

    X5R

    Z5U

    Y5V

    RoomAmbient

    U2J

  • 8

    Voltage Coefficient (Class II and III)1210 vs 0805, X7R, 10uF, 6.3V

    -60%-50%-40%-30%-20%-10%

    0%10%

    0 1 2 3 4 5 6

    Cap

    acita

    nce

    Cha

    nge

    Applied DC Bias (VDC)

    Capacitance Change vs. DC BiasRated 6.3V

    How much capacitance do you really get?

    1206

    0805

  • 9K-SIM: ESR, Z, SPICE Model, VCC, and S-Parameters

    ksim.kemet.com

  • 10

    X7R Aging Rate1.5% per Decade Hour (Limit)

    -14-12-10

    -8-6-4-202468

    101214

    1 10 100 1,000 10,000 100,000

    Time Post Heat

    Perc

    enta

    ge N

    omin

    al

    Ref

    eren

    ce

    8,77

    7 H

    r=1

    Yr

    87,7

    70 H

    r =1

    0 Y

    r

    https://ec.kemet.com/aging-calculator-for-ceramics

  • 11

    Aluminum Electrolytic

  • 12

    Aluminum ElectrolyticForm Factors

    Axial/Radial Screw Terminal Snap-In

    Single Ended SMD Motor Start

    Same construction different form factors

  • 13

    CathodePlate

    Electrolyte

    Aluminum Untreated Surface Area

    AnodePlate

    C1 C2 If C2 >> C1,then Ct ~ C1

    dAC r 0=

    0

    ( ) 932 =OAlr

  • 14

    dAC r 0=

    Electrolyte

    AnodePlate

    Aluminum Acid-Etched Surface Area

    C1 C2

    C2 must remain >> C1

    CathodePlate0

  • 15

    Anode FoilEtched Surface

  • 16

    AluminumAnode

    VFormation > VRating > Vapplication

    WetElectrolyte

    Reformed dielectric regionD

    iele

    ctric

    Dep

    letio

    n

    O-2O-2

    Reform

    Reforming / Self-Healing Wet Aluminum

    ElectrolyteCathode

    Dielectric

    Voltage contributes to operational lifetime

  • 17

    Tantalum

  • 18

    All Tantalums explode or do they?

    MnO2 MnO2 MnO2 MnO2 MnO2

    Poly Poly Poly Poly Poly

    2x Rated Voltage, applied with reverse polarity and

    >20 amps of current.

    18Every capacitor on this board failed as short

  • 19

    Stable C (No Temp or Bias Effects), DCL (t) Reliable (Decreasing FR) Long Life (Exceeds Expected Life of All Hardware) Most Volumetrically Efficient (CV/cc, E/cc)

    MilitarySpaceMedicalAutomotiveComputersTelecom

    Ta

    Ta2O5

    SEM of a Sintered Ta Anode

    Ta

    Why use Tantalum?

    Ta Oxide Dielectric

  • 20

    Polymer Electrolytic:A new kind of capacitor

  • 22

    Difference in Self-Healing

    TraditionalMnO2

    NewPolymer

    Current through fault generates enough heat and oxygen for ignition.

    Conductive polymer consumes oxygen preventing ignition.

    Tantalum CrackImpurity

    Ta Polymer

    Polymer oxidized

    Ta2O5Crack

    Impurity

    Ta MnO2

    Mn2O3Ta2O5

    If a polymer fails, it fails safely.

  • 23

    Tantalum Voltage DeratingDepend on cathode material

    Typical derating guidelines: Tantalum MnO2: 50% Tantalum Polymer: 20%(>10V), 10% (10V) Aluminum Polymer: 0%!

    35

    12

    4

    0

    126%

    Ta-Poly KOVR>10VDC

    6,[email protected]% VRated

    FR(PPM)

    1,[email protected]% VRated

    FR(PPM)

    [email protected]% VRated

    FR(PPM)

    [email protected]% VRated

    FR(PPM)

    0

    0

    0

    0

    235%

    8

    2

    1

    0

    197%68%100 PPM FR

    % VRated

    Alum-Poly AOTa-Poly KOVR10VDC

    Ta-MnO2

  • 24

    Supercapacitors

  • 25

    What Is A Super Capacitor?

    APowerCap

    BestCap

    BoostCap

    CAP-XX

    DLCAP

    EneCapTen

    EVerCAP

    DynaCap

    Faradcap

    GreenCap

    Goldcap

    HY-CAP

    Super capacitor

    SuperCap

    AS Capacitor

    PowerStor

    PseudoCap

    Ultracapacitor

    Electrostatic Double-Layer Capacitor (EDLC)

  • 26

    (Electrical) Double Layers

    1. IHP Inner Helmholtz Layer2. OHP Outer Helmholtz Layer3. Diffuse layer4. Solvated ions5. Specifically adsorptive ions6. Solvent molecule

  • 27

    Traditional and EDLCComparison

    Aluminium Reference

    +++++++

    -------

    AlAl2O3Dielectric

    Al

    +++++++

    -------

    C = QV

    -------

    +++++++

    BatteryElectrode

    SolventMolecule

    (~0.3 to 2 nm)

    C

    SymmetricSupercapacitor

    +++++++

    -------

    C

    Separator

    +++++++

    -------

    AsymmetricHybrid Capacitor

    C

    Separator

    C = 0KAd

    Surface area of carbon

    Inner Helmholtz Layer

  • 28

    Electrolytes

    Acetonitrile

    CH3CN Common for SC Dielectric constant:

    37 Burns to HCN BP: ~80C

    Propylene Carbonate (PC) C4H6O3 Dielectric constant:

    64 Destructive effect

    on graphite BP: ~240C

    Sulfuric Acid

    H2SO4 Used in lead-acid

    batteries Dielectric constant:

    ~100 BP: 337C

  • 29

    Tools

  • 30

    Mobile Catalog Apps

    Access to over 350 catalogs and 4.8MM data sheets

    www.kemet.com/mobileapps

  • 31

    ksim.kemet.com

  • 32www.engineeringcenter.com

  • 33

    [email protected] | www | twitter

    www.baldengineer.com & www.addohms.com

  • 34

    Capacitors should be voltage derated 50%

    True Or False

    It Depends

  • 35

    Summary

    Ceramic More capacitance

    Aluminum Electrolytic Longer operational life

    Tantalum Power-On Reliability

    Supercapacitors Operational Life

    Why do you voltage de-rate a capacitor?

    Slides: www.baldengineer.com/hddg11

  • 36

    Thank You!