Eurocard

Eurocard is a European standard format for PCBs, which can be plugged together into a standardized subrack. The subrack consists of a series of slotted card guides on the top and bottom, into which the cards are slid so they stand on end, like books on a shelf. At the "back" of each card is one or more connectors, which plug into mating connectors on a backplane in the rear of the subrack.

The format does not define specific connectors to be used nor the signals that are assigned to connector contacts.

The format is in widespread use in many industries, and is also the basis of the Eurorack format for modular synthesizers, popularized by Doepfer and other manufacturers.

Dimensions
The Eurocard height is specified in U (for rack unit), with 1 U being 1.75 inches. In practice heights are commonly 3U or 6U.

Eurocards come in depths that start at 100 mm and then increase in 60 mm increments. The 160 millimetres depth is the most common today, followed by 220 mm. However standard hardware is available to accommodate depths from 100 mm to 400 mm.

A single size eurocard is 100 mm x 160 mm (3U) and double size eurocard is 233.35mm x 160 mm (6U). The extra 33.35mm allows two 3U Eurocards to be supported properly next to one 6U high, with the width taken up by a card guide between the two 3U cards.