Semiconductors: let’s talk about it

            Semiconductors are solid capable of changing their condition from insulation to conductors with great ease. To use a power semiconductor correctly, it is not enough to know its current limits. In the Application Note AN949, International Rectifier shows that it takes much more. If the designer does not take into account other important information, the integrity of the component may be put at risk. See in this article how to correctly use current specifications for power semiconductors.


There are materials that do not impede the passage of electric current such as copper, iron, gold, aluminum and other metals, hence are called conductors, as it has a considerably low resistance. We can determine this resistance through Ohm’s first Law. This law states that the potential difference between two points is proportional to the electric current, and when applied to a given conductor, it is said that this resistor is ohmic or linear, and can be expressed by the formula R = V / I, where R Is the material resistance measured in Ohms (Ω), V is the voltage difference measured in Volts (v) and I is the electric current measured in Amps (A). The semiconductors can be silicon or germanium, used for the manufacture of electronic components, such as transistors. All power semiconductor devices shall operate within their dissipation range so as not to exceed their maximum temperature.


                  Thus, a major first care in any design involving these devices is in the correct choice of heat dissipation system. It is not enough to mount the device to any heatsink to ensure that it stays within the allowable temperature range. It is necessary to know how to choose the heatsink, which takes into account a careful “thermal design”, especially when high powers are involved.


Electrical insulators, also known as dielectrics, are materials that hinder the passage of electric current, that is, the electric charges do not move freely. The insulation materials can be separated according to their dielectric strength. The dielectric strength of a given material is the limit value of the electric field applied on its thickness, ie in addition to this value the atoms that make up the material ionize and it ceases to function as an insulator. Glass, rubber and oil are examples of insulating materials.












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