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About Film Capacitor

The Tecate line of film capacitors is comprehensive in it’s breadth and depth.  In addition to our vast line-up of catalog film capacitors, Tecate supports custom, application specific requirements as well. 

Film capacitors, as a category,  include any capacitor type made from plastic: polyester, polypropylene, polystyrene, etc. There are at least two types of film capacitors. Film-foil capacitors are constructed of layers (single or multiple) of plastic film dielectric wound alternately with metal foil electrodes. Metallized film capacitors are constructed of film dielectric on which the metal electrode has been previously vapor-deposited.  The layers are wound into a convoluted roll (jelly roll), with electrodes extending beyond the dielectric films.

Film capacitors are designed using a number of different dielectrics. Dielectrics are the insulating materials between the plates of the film capacitor. Materials are chosen for their ability to permit electrostatic attraction and repulsion to take place across the film.  Materials will have the property that energy required to establish an electric field is recoverable in whole or in part, as electric energy. In other words, good dielectric material is a poor conductor of electricity while being an effective supporter of electrostatic fields in film capacitors.  Common dielectrics used in film capacitors include polyester, polycarbonate, polypropylene and polystyrene. 

About Ceramic Capacitor

Ceramic is the dielectric material used in the manufacture of ceramic capacitor.  Dielectrics are the insulating material between the plates of capacitors.  This material is chosen for its ability to permit electrostatic attraction and repulsion to take place across it.  Ceramic is an excellent dielectric material because it is a poor conductor of electricity while being an effective supporter of electrostatic fields.

ceramic capacitors are manufactured using a tape casting process wherein thin layers of conductive electrodes are separated by a dielectric layer, and a kind of multi-layer “sandwich” is formed to create a ceramic capacitor with a very large surface area in a very compact size.  Recently, the combination of nickel electrodes and the ability to cast very thin layers has allowed the capacitance range of ceramic capacitors to exceed more than 100μF in an 1812 package, using X5R dielectric material.  With the ability to stack hundreds of layers to form a single high-density, high-capacitance multilayer ceramic capacitor, new application opportunities, that were previously the sole domain of tantalum capacitors, are now available for ceramic capacitors.  One of the driving forces for the increased capacitance values in ceramic capacitors was the tantalum shortage of 2000.

Prior to the use of nickel electrode systems, Palladium (Pd) and Silver (Ag) were the most common electrode materials.  This precious metal became cost prohibitive when making very high-capacitance, high-layer count ceramic capacitors.  Palladium and silver are still widely used for ceramic capacitors with lower capacitance values.

About Tantalum Capacitor

Tantalum Capacitors are used in electronic devices including portable telephones, pagers, personal computers, and automotive electronics.  When selecting between available tantalum Capacitors, there are a number of key specifications to keep in mind when designing in a tantalum Capacitor.  These  include capacitance value, capacitance tolerance, dissipation factor, leakage current, and equivalent series resistance (ESR).  The designer must also consider the board interface requirements.  Tecate tantalum capacitors are available in radial leaded or surface mount configurations.

Capacitance is a measure of the energy storage ability of a tantalum Capacitor, given as C = K A/D, where A is the area of the electrodes, D is their separation, and K is a function of the dielectric between the electrodes. The formula yields a result in farads (F), but a farad is so large that the most commonly used values are expressed in microfarads (µf = 10-6F). 

The dissipation factor (DF) is the ratio between the resistive and the reactive part of the impedance of the tantalum capacitor submitted to a sinusoidal voltage of specified frequency. It is a measure of the losses in the capacitor.  

Leakage current is measured as the current flowing from one conductor to an adjacent conductor through an insulating layer. The leakage current in tantalum Capacitors is measured after 3 minutes at 25°C, through a 1k resistor connected in series with the capacitor, and with rated voltage applied.

Equivalent series resistance (ESR) represents the extent to which the capacitor acts like a resistor when charging and discharging. This functions via a resistive element within the capacitor model, found in both the AC and DC domains.  The lower the ESR the higher the current carrying ability of the tantalum capacitor.