Flat cables, also known as ribbon cables, are cables with multiple conductive wires running parallel to each other on the same flat plane.
When flat cables were first introduced, they were produced in various colors and diameters. Later, methods and materials were developed to standardize the design, spacing, and insulation thickness of the cables to simplify and reduce the cost of ribbon cables. The latest and most useful and cost-effective insulation displacement connectors (IDC) were introduced. To reduce the risk of reverse connections, one side of the cable is usually marked with a red stripe. Traditionally, the striped side of the cable is connected to pin 1 on the connector. This identification method is suitable for cables consisting of two or more IDC connectors, each connected to a connector on each cable, but it is less preferred for cables where individual wires or small cable groups need to be terminated separately.
To facilitate the identification of individual conductors in a cable, ribbon cable manufacturers introduced the rainbow ribbon cable, which uses a repeating color pattern borrowed from the standard resistance color code (Brown is pin 1 or pin 11 or pin 21, etc., Red is pin 2 or pin 12 or pin 22, etc.). Sometimes it is affectionately known as "hippie cable" by users due to its distinctive appearance.
Ribbon cables are typically specified by two numbers: the spacing or pitch of the conductors and the number of conductors or tracks. The most common spacing is 0.05 inches (1.27 mm), which allows for a two-row connector with a 0.1-inch (2.54 mm) pin pitch. These types are used for many types of equipment, especially interconnections within enclosures.
Depending on the availability of standard connectors, the number of conductors is often limited to several values, including 4, 6, 8, 9, 10, 14, 15, 16, 18, 20, 24, 25, 26, 34, 37, 40, 50, 60, 64, and 80. The wire is typically twisted copper wire, usually 0.32, 0.20, or 0.13 mm² (22, 24, or 26 AWG). Although it is sometimes possible to remove and reuse IDC connectors, they are not designed to allow this easily.
Due to the simplicity and standardization of cables and their low cost, ribbon cables have become a long-lasting cable used in computers, printers, between motherboards and drives, and many electronic devices.