In electronics, a Lead is an electrical connection consisting of a length of wire or a metal pad (surface-mount technology) that is designed to connect two locations electrically.
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
- Act as a heatsink.
The tiny leads coming off through-hole electronic components are also often called “pins“; in ball grid array packages, they are in form of small spheres, and are therefore called “balls“.
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).