Some Background on Metal Film Resistors

Document Sample
Some Background on Metal Film Resistors Powered By Docstoc
					              Some Background on Metal Film Resistors
Resistors:

You could find resistors in nearly all electronic equipment and are generally a typical element of an
electrical network along with electronic circuits. These practical resistors are constructed from various
films, compounds and also resistance wire. These wires are manufactured from high-resistivity alloy
including nickel-chrome.

The characteristics of resistors are specified by its level of resistance: typical resistors are made over a
wide range of more than nine orders of magnitude. Depends upon its certain application, when finding
the level of resistance for any electronic device, one must always pay attention to the manufacturing
tolerance of the chosen resistor. In many precision applications, it may also be crucial that you pay
attention to the temperature coefficient of the resistance. Resistors with higher power ratings are
physically much bigger and might involve heat sinks. In a high-voltage circuit, special attention must be
given to the rated maximum working voltage of the resistor.

What are Metal Film Resistors:

A resistor where the resistive element is a film of metal or metal alloy is known as a metal film resistor.
With this type of resistor, the metal film is settled on an insulating substrate similar to ceramic. These
resistors have excellent operational features, like low noise and minimal drift. Sometime they're also
recognized as metalized resistor.

Most of the time, these metal film resistors can be used for military and high-end industrial purposes.
The most common sorts of axial-leaded metal film resistors are hardly any more expensive in
comparison with carbon film and, given their excellent features, especially temperature coefficient,
noise and power handling ability, many tools producers don't think it is beneficial to bother with carbon
film. Most standard metal film resistors have a temperature coefficient in the order of 50 to 200
ppm/°C. Nevertheless, you will find varieties available with a temperature coefficient of under 10
ppm/°C.
Design:

Metal Film Resistors are designed and manufacture to meet great requirements. Often, the metal inside
the metal film resistor is made of NiCr (nickel-chromium) of diverse composition to create several array
of resistance. Film of this alloy is then plated onto a ceramic alumina substrate. The leads and end caps
are force-fitted to a tubular assembly and the resistance element is then trimmed to value by slicing a
helical pattern of governed dimensions in it. With this, the exact same film composition can be used to a
wide range of resistance values. The complete part is then protected in epoxy and marked. We can see
however, that the drawback to the helical trimming method is that it limits its pulse handling ability as
well as increases the resistor’s inductance.

Normal Purposes:

Stability, TCR and tolerance are some of the attributes these particular metal film resistors are good at.
Caused by a low voltage coefficient, these resistors also have low noise attributes plus a high linearity.
For that reason, in circuits where limited tolerance, low temperature coefficient and low noise
components are essential, often metal film resistors are utilized. As said recently, lots of people would
rather make use of metal film resistors because they are only a little more pricey as compared to carbon
film resistors. Active filters or bridge circuits are only some uses of such resistors are telephony or
calibration applications.

Source: http://www.resistorguide.com/metal-film-resistor/

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:23
posted:1/9/2013
language:
pages:2
Description: You could find resistors in nearly all electronic equipment and are generally a typical element of an electrical network along with electronic circuits. These practical resistors are constructed from various films, compounds and also resistance wire.