Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Dispositivos Semiconductores

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Capacitores

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Modelo ideal

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (V) Rated Voltage (U R )  Direct voltage for which the C has been designed Operating Voltage (U OP )  Range (between 0V and Ur) typ. 60% Surge Voltage (U S )  For short periods of time Superimposed AC, ripple voltage Reverse voltage

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (C) AC/DC capacitance  AC value is measured at 20 o C / 100Hz-120Hz Rated capacitance  Nominal value Tolerance  Described by a code

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (C) Temperature dependence Frequency dependence Charge-discharge proof  Frequent charging/discharging cycles may lead to capacitance variation

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (tan δ) Dissipation factor tan δ

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (tan δ) Tan δ variation with temperature and frequency As freq. increases the capacitive impedance reduces and the dissipation factor gets worse Increasing the temperature results in better dissipation factor

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical parameters (Z) R = dielectric losses, series resistance L = winding and terminals (only depends on f ) C and R depend on temp. and f Fig. Temperature behaviour is for an Al electrolytic capacitor

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (I) Leakage current: depends on time, temperature and applied voltage

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (I) Ripple current: rms value of circulating current Depends on temp. and frequency Useful life: life achieve without exceeding a specified failure rate. Depends on:  Temperature  Ripple current  Voltage

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrical Parameters (I) Useful life:  Calculation

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Climatic conditions UCT: Upper category temperature LCT: Lower category temperature Limits within cap. Can be continuously operated Storage temperature There are also restrictions on mechanical stress

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Capacitor Types Electrolíticos  Al  Ta Cerámicos  G1  G2 Film  Polietileno (polyester)  Polipropileno  Metalizados Mica

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Capacitor Types: Values Electrolíticos  Al  Ta Cerámicos  G1  G2 Film  Polietileno (polyester)  Polipropileno  Metalizados Mica  0.47µF µF / 5V-500V  220nF-100µF / 1V – 50V  0.5pF – 560pF / 63V – 500V  100pF – 470nF / 53V – 500V  1nF - 1µF / 100V – 1000V  10nF - 10µF / 63V – 1000V  2pF – 22nF / 250V – 4000V

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Capacitor Types: Tolerances Electrolíticos  Al  Ta Cerámicos  G1  G2 Film  Polietileno (polyester)  Polipropileno  Metalizados Mica  -10% / +100 %  +- 20%  2%, 5%, 10%  +- 20%  2%, 5%, 10%  0.5% - 20%

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 AL Electrolytic

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrolytic (Al) Capacitors Polar elements. Only block current in one direction Anode is Al of great purity. Cathode is electrolyte (liquid) and paper

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrolytic (Al) Capacitors Anode is etched to provide more surface Dielectric is obtained by oxidation of Al (<1um thickness) Big values of capacitance

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 V-I curve After the forming voltage (Uf) current increases Safe operation is ensured below Ur

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Temperature effects With decreasing temperature, the viscosity of the electrolyte increases, thus reducing its conductivity.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Datasheet

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Tantalium-Niobium Caps.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrolytic (Ta-Nb) Capacitors ε r is 27 for Ta, 41 for Nb Polar elements. Only block current in one direction

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Frequency dependence

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Z and ESR

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Low ESR series

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Ultra-low ESR

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Maximum V,I vs T and I vs. f

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Dissipation factor (vs. f, T)

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Leakage

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Ceramic

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Ceramic capacitors they all have the oxide ceramic dielectric in common. Ceramic generally means that an inorganic polycrystalline body is formed by sintering at high temperatures. By means of special production methods, extremely thin layers of ceramic materials can be obtained.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Classification Class 1 capacitors  The dielectric (200) primarily consists of a mixture of metal oxides and titanates.  Defined linear temperature coefficient with reversible temperature dependence  Capacitance does not vary with voltage.  Low losses at frequencies up to the UHF range  High insulation resistance  Applications: resonant circuits, filters, timing elements

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Classification Class 2 capacitors  The dielectric ( 200 to 10000) primarily consists of titanates (barium, calcium, strontium) and zirconates.  Non-linear dependence of capacitance on temperature and voltage  Somewhat higher losses and lower insulation resistance than class 1 capacitors  Capacitance decreases according to a logarithmic function (ageing).  High capacitance values even with small-size capacitors are possible  Applications: coupling, blocking, filtering.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Class 1: Temperature dependence

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Class 2: Temperature dependence

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Termal characteristics Change more (class 2) or less (class 1) with temperature. Change in crystalline structure  capacitance value of high K materials (with a high dielectric constant, e.g. X7R, Z5U) class 2 drastically decreases above the Curie point  materials with a low dielectric constant (C0G) class 1, dissipation factor increases considerably at high temperatures. high ambient temperature and high electrical energy exchange contributes to heating the capacitor.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Datasheets (C0G)

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Datasheets (X7R)

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Frequency response

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Film Capacitors

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Classification T ˆ= Polyethylene terephthalate (PET) P ˆ = Polypropylene (PP) N ˆ= Polyethylene naphthalate (PEN) An M (ˆ = Metallization) is prefixed to the short identification code of capacitors with metallized films.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Winding method

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Stacked method The “master capacitors” are produced under well-defined and constant conditions. Since each individual layer acts as a separate capacitor element, any damage to the contacts due to overloading is restricted to the respective capacitor element and does not affect the entire capacitor

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Film vs. Foil

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Self-healing property Capacitors with metallized plastic film have a decisive advantage over capacitors with metal foil electrodes: they have self-healing properties.  Self-healing properties permit utilization of full dielectric strength of dielectric materials of metallized film capacitors  metal-foil electrode capacitors must always be designed with a safety margin to allow for any possible faults in the dielectric.  Metallized types thus have a distinct size advantage, which is particularly apparent with the larger capacitance ratings.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Self-healing property

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Temperature Polypropylene capacitors have negative temperature coefficient Polyester capacitors have positive temperature coefficient

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Humidity the dielectric and the effective air gap between the films will react to changes in the ambient humidity

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Frequency MKT, MFT and MKN MKP and MFP capacitors: Up to a frequency of 1 MHz, the capacitance remains virtually unaffected by the frequency.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Maximum voltage (T)

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 V/I limitations A) corona discharge B) Thermal dissipation C) Leads resistance

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Tan δ Polypropelene capacitors

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Tan δ The dielectric of MKT capacitors contributes a considerably greater dielectric component tan δD MKT capacitors display a noticeably higher overall dissipation factor, especially at lower frequencies than MKP and MKN capacitors

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Datasheets

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Polyester Metallized Polyester Capacitors (Mylar)  With tolerance of 10%  Temperature range -40oC to +85oC.  Non inductive.  Dielectric strength of 150% of rated voltage for less than 5 sec

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Polyester Metallized Polyester Film Capacitors  With tolerance of 10%.  Operating temperature -40oC to +85oC.  Non Inductive Design  Compact Size  Available in rolls of 100 or 1,000 at special prices.

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Mica Advantages: dielectric material (mica) is inert.inert  Does NOT change physically or chemically with agephysicallychemically  Good temperature stability.  Very resistant to corona damagecorona  Unless properly sealed, susceptible to moisture pick-up (increases the power factor and decrease insulation resistance).  Higher cost (scarcity of high grade dielectric material) and manually- intensive assembly. Silver mica capacitors have the above mentioned advantages. In addition, they have much reduced moisture infiltration. Silver mica capacitors infiltration

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Summary

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Summary Ceramics: low stability and precision. Electrolytic - Same as ceramics except they have much smaller physical size for a given value. Usually polarized. Large tolerances Tantalum - Better characteristics than electrolytic but still small for high capacity values. Polarized. Smaller tolerance than electrolytic Poly film – (polyester or polypropylene) --mostly replaced paper capacitors-- Slightly better characteristics than common ceramics. Usually very low leakage currents. Mica/Silver Mica - Temperature stable, low dissipation factor. Usually large physically. Polystyrene, Teflon - Very temperature stable. Polystyrene breaks down, however, at high temps (say >80C) Glass, Air, Oil – Not Common(HV work, big motors)

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Electrolytic Capacitors Tantalum  Small size  Large values  Medium inductance  Quite high leakage  Usually polarized  Expensive  Poor stability  Poor accuracy Aluminum  Large values  High currents  High voltages  Small size  High leakage  Usually polarized  Poor stability  Poor accuracy  Inductive

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Mica Widely used in low and medium power RF equipment Low loss at HF Low inductance Very stable Available in 1% values or better Quite large Low values (<10 nF) Expensive

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Film Polyester  0.3% to 0.5%  Moderate stability  Low cost  Wide temperature range  Low inductance (stacked film)  Large size  High inductance Polypropylene  0.001% to 0.02%  Inexpensive  Wide range of values  Large case size  High inductance

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Appendix

Copyright Pedro Julián. Dispositivos Semiconductores - DIEC/UNS 2008 Surface mount formats capacitors 1. A-case (Tantalum cap) 2. D-Case (Tantalum cap) 3-4 Electrolytic cap Ceramic Ceramic Ceramic 8. High Q Porcelan RF 9. Variable Trimmer