What are Ribbon (Flat) Cables?

Meet the Cable: Ribbon or Flat Cable

Ribbon cables, also known as flat or planar cables, feature a row of conductive wires running in parallel within a wide, flat, ribbon-shaped cable substrate. Ribbon cable can be folded and bent, providing great design flexibility.

Adafruit ribbon cable from DigiKey

The ribbon cable was invented in 1956 by the Cicoil Corporation (a Trexon company) for IBM for use in mainframe computer devices like card readers and punching machines, where cables needed to fit into tight spaces. NASA began using ribbon cable in the 1960s and the product played a role in milestone aerospace applications like the first lunar landing. In early consumer market computers, they were frequently used in computers and printers to connect internal drives like hard drives, floppy drives, and CD-ROM drives to the motherboard via parallel ATA (PATA) interfaces. Although newer technologies such as SATA and flat flexible cables (FFCs) have largely replaced ribbon cables in modern computers, they are still used in some industrial, automotive, and embedded systems.

Design Notes

Connectorization: Ribbon cables are typically used with insulation displacement connectors (IDCs). Each conductor is color-coded or uniformly insulated, and they are usually connected to insulation-displacement connectors (IDCs), which allow for easy and reliable termination without stripping the wires. These connectors are commonly used with headers on circuit boards, especially in legacy or industrial systems.

Ribbon cables can carry both data and power, though they are typically used for data transmission.

Amphenol Communication Systems FFC jumpers demonstrate a modern iteration of ribbon cable.

Standardization: Ribbon cables typically come with a standard number of conductors (10, 20, 40), or more, depending on the application. The most common pitch standard (spacing between the individual conductors) for ribbon cables is 0.050 inches (1.27 mm). Other pitches include 0.100 inches (2.54 mm).

To help with identifying individual wires, a common color-coding convention is used: Standard rainbow ribbon cable uses a repeating color sequence for every 10 wires: brown, red, orange, yellow, green, blue, violet, gray, white, and black. Wire 1 is typically marked with a red stripe on monochrome cables.

Material specifications: Ribbon cable is typically made from copper wires suspended inside PVC material. Teflon, polyethylene, and thermoplastic elastomer are also used. Some ribbon cables also have a laminated sheath incapsulating the assembly.

Adam Tech’s FFCs are a customizable flat cable product based on the ribbon cable. They are available in a wide variety of options include 0.50 mm – 2 mm centerline spacing, nearly any length of contact number required, and configurability of contacts location on the same side, alternate side, or a combination of both.

Physical properties:

Because the wires are arranged in parallel and in close proximity, ribbon cables can be susceptible to electromagnetic interference (EMI) and crosstalk if not properly shielded. For this reason, they are best suited for short-distance, low-speed communication tasks.

Ruggedization: Some high-performance ribbon cables withstand high temperatures, abrasion, flexure and chemical exposure.

Molex Temp-Flex High-Performance Flat Ribbon Cables are designed specifically to prevent the signal interruptions that are prevalent in harsh environments due to failures with PVC and TPE cables.

Markets and Applications

Consumer, Datacom, Industrial

Suppliers

Adam Tech, Amphenol Communications Solutions, Axon’ Cable, DigiKey, Harwin, I-PEX, JAE, KYOCERA AVX, Molex, Mouser Electronics, Phoenix Contact, Samtec Inc., Trexon, TE Connectivity

Related products

IDC connectors

FFCs and FPCs

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