Eurocard (printed circuit board)

Eurocard is a European standard format for PCB cards that 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 that closes the rear of the subrack.

As the cards are assumed to be installed in a vertical orientation, the usual meanings of height and width are transposed: A card might be 233.35 mm "high", but only 20 mm "wide". Height is measured in rack units, "U", with 1 U being 1.75 in (44.45 mm). This dimension refers to the subrack in which the card is to be mounted, rather than the card itself.

Enclosure heights are multiples of 3U, with the cards always 33.35 mm (1.313 in) shorter than the enclosure. Two common heights are 3U (a 100 mm card in a 5.25 in (133.35 mm) subrack) and 6U (a 233.35 mm card in a 10.5 in (266.70 mm) high subrack). As two 3U cards are shorter than a 6U card (by 33.35 mm), it is possible to install two 3U cards in one slot of a 6U subrack, with a mid-height structure for proper support.

Card widths are specified in horizontal pitch units "HP", with 1 HP being 0.20 in (5.08 mm).

Card depths start at 100 mm (3.937 in) and increase in 60 mm (2.362 in) increments. The most common today is 160 mm (6.299 in), but standard hardware is available for depths of 100 mm (3.937 in), 160 mm (6.299 in), 220 mm (8.661 in), 280 mm (11.024 in), 340 mm (13.386 in), and 400 mm (15.748 in).

The Eurocard mechanical architecture was defined originally under IEC-60297-3. Today, the most widely recognized standards for this mechanical structure are IEEE 1101.1, IEEE 1101.10 (also known commonly as "dot ten") and IEEE 1101.11. IEEE 1101.10 covers the additional mechanical and electromagnetic interference features required for VITA 1.1-1997(R2002), which is the VME64 Extensions standard, as well as PICMG 2.0 (R3.0), which is the CompactPCI specification.

The IEEE 1101.11 standard covers rear plug-in units that are also called rear transition modules or RTMs.

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