Sizes
Ribbon cables are usually specified by two numbers: the spacing or pitch of the conductors, and the number of conductors or ways. A spacing of 0.05 inch (1.27 mm) is the most usual, allowing for a two-row connector with a pin spacing of 0.1 inch (2.54 mm). These types are used for many types of equipment, in particular for interconnections within an enclosure. For personal computers, this size is used today in floppy-disk-drive cables and older or custom Parallel ATA cables.
Based on availability of standard connectors, the number of conductors is usually restricted to a few values, These include 4, 6, 8, 9, 10, 14, 15, 16, 18, 20, 24, 25, 26, 34, 37, 40, 50, 60, 64 and 80. The wire is usually stranded copper wire, usually either 0.32, 0.20, or 0.13 mm2 (22, 24, or 26 AWG).
Finer and coarser pitch cables are also available. For instance, the high-speed ATA interface cable used for computer hard disk interfaces ULTRA-ATA has 0.025-inch (0.64-mm) pitch. Finer pitches, as small as 0.3 mm, are found in portable electronic equipment, such as laptops; however, portable electronic equipment usually uses flexible flat cables (FFC).
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