ResistorTYPES OF MOUNTING AND PHYSICAL SIZES

RESISTOR SIZES.

Resistors are available in almost any size ranging from 0.065 inches diameter by.125 inches long to 12 inches in Diameter to several feet high (for very high voltage resistors). They come in almost any shape that is imaginable. The most common form is cylindrical with leads coming out either end. They can be manufacture in custom shapes to fit the available space when quantities justify.  Riedon is a manufacturer of resistors and can be found at http://www.riedon.com

TYPE OF MOUNTING.

Resistors can be made with almost any type of mounting. Special mountings can be designed to fit the customer’s needs if the need arises. Some of the more common means of mountings are listed below. The term “Leads” is used in the general sense as a means of connecting the resistor. They may be lugs, wire leads, pins, or any means of connecting the resistor to the circuit.

Surface Mount

Resistors are available in a surface mounting configuration. This is generally associated with chip resistors that are mounted by solder reflow techniques.

Resistors color codeFuse Clip Mounting.

The fuse clip type is made such that it will mount directly into a fuse clip. Fuse resistors are sometimes made like this.

Single Inline Packaging (SIP).

The Single Inline Package is normally associated with resistor networks consisting of several resistors in the same package. It is a rectangular flat shaped package with the several leads coming out one surface generally the narrow, long surface.

Dual Inline Package (DIP).

The Dual Inline Package is again normally associated with resistor networks. The main difference is that leads extend out both narrow, long surfaces and are formed to either flush mount on a PC Board or thru hole mount on a PC board.

Flat Packs.

The Flat Pack are roughly the same as Dual Inline Packaging except the leads come straight out and are not formed for surface mounting or thru hole mounting. This is just a variation of DIP mounting.

Axial Leads – Axial Lead mounting is what most of us are familiar with using. It consists of a cylindrical (or rectangular or any shape body) with the leads extending out either end parallel to the resistor’s major axis.

Radial Leads.

Radial Lead mounting is similar to Axial Lead mounting except the lead come out of the body perpendicular to its major axis.

PC Mounting.

PC mounting consists of both leads of the resistor coming out the same surface so that it is easier to mount a resistor (or any other device) vertically. The resistor may be rectangular or cylindrical.

4 Terminal Mounting.

Most styles will offer a 4 terminal means of mounting for low values. It is fixed and prevents changes in the value due to mounting variations.

RESISTOR TYPES.

PRECISION WIREWOUND.

The Precision Wirewound is a highly accurate resistor with a very low TCR and can be accurate within.005 %. A temperature coefficient of resistance (TCR) of as little a 3 part per million per degree Celsius (3ppm/oC) can be achieved. These components are too expensive for general use and are normally used in highly accurate DC applications. The frequency response of this type is not good. When used in an rf application all Precision Wirewound Resistors will have a low Q resonant frequency. The power handling capability is very small. These are generally used in highly accurate DC measuring equipment, and reference resistors for voltage regulators and decoding networks.

The maximum value available is dependent upon physical size and is much lower than most other types of resistor. In some cases, particularly if the tolerance is very low and the TC is low, the rated power is reduced to improve resistor stability through life. The materials used in these resistors are highly stable heat treated materials that do change under extended heat and mechanical stress.

There is little detectable noise in this type of resistor. The stability and reliability of these resistors is very good and their accuracy can be enhanced by matching the absolute value and the temperature coefficient over their operating range to achieve very accurate voltage division.

Resistors are available in almost any size ranging from 0.065 inches diameter by.125 inches long to 12 inches in Diameter to several feet high (for very high voltage resistors). The term “Leads” is used in the general sense as a means of connecting the resistor. They may be lugs, wire leads, pins, or any means of connecting the resistor to the circuit.

The maximum value available is dependent upon physical size and is much lower than most other types of resistor. In some cases, particularly if the tolerance is very low and the TC is low, the rated power is reduced to improve resistor stability through life.