Lead (electronics)

Leads are used for many purposes, including: transfer of power; testing of an electrical circuit to see if it is working, using a test light or a multimeter; transmitting information, as when the leads from an electrocardiograph are attached to a person's body to transmit information about their heart rhythm; and sometimes to act as a heatsink.

Many electrical components such as capacitors, resistors, and inductors have only two leads, while some integrated circuits can have several hundred or even more than a thousand for the largest ball grid array packages.

Integrated circuit pins often either bend under the package body like a letter "J" (J-lead) or come out, down, and form a flat foot for securing to the board (S-lead or gull-lead).

For many circuit designs it can be assumed that the leads do not contribute to the electrical effects of individual components.

The leads are often metal connections that run from the rest of the circuit to the materials that each component is made of.