Introduction:

Eurocard is a European standard format for printed circuit boards, which can be plugged together into a standardised subrack, otherwise known as a shelf, card cage or carton. The subrack consists of a series of slotted card guides on the top and bottom, into which the cards slide so they stand on end, like books on a shelf. At the "back" of each card are one or more connectors, which plug into mating connectors on a backplane or connector frame and this provides the connectivity to each card and close the rear of the subrack. The methods of construction for a subrack are varied and Vero Technologies specialises in supplying component parts for use with most options, including guides connector frames, card or PCB handles, development cards and prototyping boards as well as backplanes and test extenders.

Our range of Eurocard format prototyping cards have been designed to comply with the requirements of the international packaging specification IEC297 and the associated connector specifications DIN41494, DIN 41612 and DIN 41617.

The Eurocard packaging system is a complex mixture of English and metric dimensions. Although this may seem confusing, widespread conformance to the standard dimensions means that users are not troubled by these issues, and intermatability of devices and components designed to meet these “rules” can be guaranteed.

Standard pitch:

Eurocard subrack’s have standardized sizes in all three dimensions. Height is specified by the unit 'U' see below, (which stands for 'Unit or Rack Unit'), with 1 U being 1.75 inches. Width is specified by the unit 'HP' (which stands for 'Horizontal Pitch')or 'T' with 1 HP being 0.20 inches. The smallest height is 3U.

Background information on the Eurocard format:

The height of a Eurocard is less than the height of the sub rack or chassis by 33.35 mm to allow space for panels and card guides. The height of the card in a 3U rack is therefore 100 mm. As two stacked 3U cards are about the same height as a 6U card (see Notes) this scheme allows racks to be constructed which mix 3U and 6U cards. Front panels are also slightly smaller than the rack size, and the typical panel height for a 133.35 mm 3U rack is 130 mm. Eurocard’s come in modular depths that start at 100 mm and then increase in 60 mm increments.

Popular Card Sizes:

The standard allows for a vast number of permutations, but in practice there are only comparatively few sizes in use. Heights are commonly 3U or 6U, and only occasionally 9U. The 160 mm depth is the most common today and is commonly referred to as the standard size, followed by 220mm which is known in the industry as an “extended Eurocard”. However
standard hardware is also available to accommodate depths of 100 mm, 280 mm, 340 mm, and 400 mm.

The image on the right is of single euro depth (160mm) cassette modules in 3U and 6U heights.

Notes:

A 3U high subrack is 133.35 mm (5.25 inches) high and accepts a 3U Eurocard which is 100 mm high. A 6U high subrack is 266.7 mm (10.5 inches) high and accepts with the correct arrangements of guides etc both 3U Eurocard's, 100mm high, and 6U Eurocard’s which are 233.35 mm high.

Standards and architecture:

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 EMI features required for VITA 1.1-1997(R2002) (VME Industry Trade Association) which is the VME64 Extensions standard (see below for an explanation of VME)
as well as PICMG ( PCI Industrial Computers Manufacturers Group) 2.0 (R3.0) which is the CompactPCI (see below for an explanation of CompactPCI)specification. The IEEE 1101.11 standard covers rear plug-in units that are also called rear transition modules or RTMs.

A brief explanation of the specification is here -

The Eurocard is a mechanical system and does not define the specific connector to be used or the signals that are assigned to connector contacts. The connector systems that are commonly used with Eurocard architectures include the original DIN 41612 connector that is also standardized as IEC 60603.2, please see below for more information. This is the connector that is used for the VMEbus standard which was IEEE 1014. The connector known as the 5-row
DIN which is used for the VME64 Extensions standard is IEC 61076-4-113. The VME64 Extension architecture defined by VITA 1.1-1997 (R2002). Another popular computer architecture that utilizes the 6U-160 Eurocard is CompactPCI and CompactPCI Express. These are defined by PICMG 2.0R3 and PICMG Exp0 R1 respectively. Other computer architectures that utilize the
Eurocard system are VXI (VME eXtension for Instrumentation a version of VME dedicated to instrumentation systems), PXI (CompactPCI eXtension for Instrumentation a version of VME dedicated to instrumentation systems, and PXI Express.

A computer architecture that used the 6U-220 Eurocard format was Multibus-II which was IEEE 1296. Sun Microsystems used the 9U-400 format for their VMEbus based systems. Because the Eurocard system provided for so many modular card sizes and because connector manufacturers have continued to create new connectors which are compatible with this system, it is a popular mechanical standard which is also used for innumerable "one-off" applications. Conduction-cooled Eurocard’s are used in military and aerospace applications. They are defined by the IEEE 1101.2-1992(2001) standard. The use of prototyping and development boards and associated products is therefore a wide market as these products enable the fast development of circuits at low cost to provide the designer with the ability to try out his ideas before
developing the design to a prototype or production stage.

This is where the Vero product range of development products offers the broadest range of products available and in association with our range of plastic and metal enclosure products offers significant reductions in time and effort in sourcing parts and thereby dramatically reducing the cost and time of development.

Explanation of rack Unit or “U”

A rack unit or U (less commonly, RU) is a unit of measure used to describe the height of equipment intended for mounting in a 19-inch rack or a 23-inch rack (the dimension referring to the width of rack). One rack unit is 1.75 in (44.45mm) high. One rack unit is commonly written as "1U"; similarly, 2 rack units are "2U" and so on. The size of a piece of rack mounted
equipment is usually described as a number in "U" and unless otherwise stated is assumed to be full width in the rack space. Where equipment is less than full width these are usually specified in terms of “HP”. (see below for an explanation of this unit) The majority of racking systems are based on 19” racks and in this case the standard full width unit is 84HP. Equipment width below 84 HP 3U 42HP for example and this would be a 3U high half width unit. This division can be within a shelf in the rack, so two 42 HP wide units could reside on the same shelf as self contained units, or as a sub divided sub rack, with each portion of the subrack self contained. A front panel or filler panel in a rack is not an exact multiple of 1.75-inches (44.45 mm). To allow space between adjacent rack mounted components, a panel is 1/32 inch (0.031 inch or 0.79 mm) less in height than the full number of rack units would imply. Thus, a 1U front panel would be 1.719 inches (43.66 mm) high. If n is number of rack units, the formula for panel height is h = (1.750n - 0.031) inch = (44.45n - 0.79) mm.

The images to the right show examples of PCB front panels in this case 6U and 3U by 4HP wide.

Explanation of the term” Rack”

A 19-inch or 23-inch rack is a standardized (EIA 310-D, IEC 60297 and DIN 41494 SC48D) system for mounting various electronic modules in a "stack", or rack, 19 inches (480 mm) or 23 inches (584 mm) wide. Equipment designed to be placed in a rack is typically described as rack-mount, a rack mounted system, a rack mount chassis, subrack, rack mountable, or occasionally, simply shelf.

Most racks are manufactured from sheet steel or aluminium although some use extrusions and corner pieces to build the frame. The frame is then “clad” with outer panels either for cosmetics or to provide restricted access via locks, or other required features. These features include EMC RFI sealing as well as IP sealing for harsh environments. The most common height sold is the 42U form: that is, a single rack capable of holding 42 1U “pizza box” servers, or any combination of 1U, 2U, 3U or other height units. The racks also often include thermal monitoring and control systems as well as alarms and status monitoring systems that report via systems to a central core.

Because of their origin as mounting systems for railroad signaling relays, they are still sometimes called relay racks, but the 19-inch rack format has remained a constant while the technology that is mounted within it has changed to completely different fields. In the telecommunication, computing, audio, entertainment and other industries this 19” racking method has become the norm, though the Western Electric 23-inch standard, with holes on 1-inch centres, prevails in telecommunications.

19-inch racks are often used to house professional audio and video equipment, including amplifiers, effects units, interfaces, headphone amplifiers, and even small scale audio mixers. They are also widely used for computer server equipment, allowing for dense hardware configurations without occupying excessive floor space or requiring shelving. A third common use for rack-mounted equipment is industrial power, control, and automation hardware, typically in 46U racks. Typically, a piece of equipment being installed has a front panel height approximately 1/32-inch (0.78mm) less than the allotted number of U’s. This dimension will vary from manufacturer to manufacturer but the purpose, is to ensure “clearance” between the mounted subracks to prevent interference if one item is added or removed in service.

The image to the right is of a 42U high Vero Imrack 1400 600 X 600 19 inch rack.

Bus Systems Using The Eurocard Format.

Multibus – II:

Multibus II, though not often considered as a fault resilient bus architecture, can be used as the basis for systems that exhibit degrees of fault resilience. The bus definition, IEEE 1296, together with further software definitions of Multibus Systems Architecture provide a flexible hardware and software framework for highly reliable systems. This coupled with ongoing developments, like on-line service and repair, by the Multibus Manufacturers Group can provide cost effective solutions to the classic problems of fault resilience. The result is that although an older system this “bus” structure has found use in many areas where this fault tolerance is crucial – for example traffic control systems, railway applications as well as industrial process control and monitoring.

The image to the right here is of a 6U PCB Assembly

VME:

VMEbus is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. It is physically based on Eurocard sizes, mechanicals and connectors, but uses its own signalling system, which Eurocard does not define. It was first developed in 1981 and continues to see widespread use today.

The image to the right here is of a Vero 9U high VXI rack

CompactPCI:

A CompactPCI (cPCI) system is a 3U or 6U Eurocard-based industrial computer, and has been designed for hot pluggable cards from the start, and where all boards are connected via a passive PCI backplane. The pin assignments of the connectors are documented in standards, published by the organization PICMG The connectors and the electrical rules allow for 8 boards in a PCI segment. Multiple segments can be achieved but due to the speed and propagation delays in the system at its design this can only be achieved using active “bridges” to continue the bus.

Unlike the original Eurocard solutions such as VME, which use connectors with a 0.1-inch pin spacing, CompactPCI cards use metric connectors with a 2-millimeter pin spacing, designed to the IEC 1076 standard. However although the connector systems are different the principles behind the system are similar in that they both use Eurocard's as the basis for the structure and define the positioning and allocation of functions in the equipment. 3U boards have a
110-pin connector (J1), with an optional 110-pin connector (J2), which carries either user-defined I/O or the upper 32-bits of an optional 64-bit PCI bus. 6U cards have an identical J1, a J2 that is always used for 64-bit PCI, as well as J3, J4, and J5 connectors for a variety of uses either as user-defined I/O or specified signaling such as Telephony and/or Ethernet signalling.

CompactPCI was initially ratified as PICMG 2.0 in late 1995 as a passive backplane for PCI signaling. The 2.x series of specifications from PICMG provide support for a variety of technologies including Hot Swap (PICMG 2.1), Telephony signaling (PICMG 2.5) and most notably the expansion of the architecture to include switched Ethernet (PICMG 2.16).
CompactPCI has grown to include a variety of technologies cantered around the application of the 2mm HM connector on the 3U and 6U form factor. In fact many systems are implemented with no PCI bus on the backplane, such as those implemented with switched Ethernet board interconnection (PICMG

The image to the right here is of a Vero CompactPIC chassis.

Standards Organisations:

ANSI

The American National Standards Institute or ANSI is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international standards so that American products can be used worldwide. For example, standards make sure that people who own cameras can find the film they need for that camera anywhere around the globe. ANSI accredits standards that are developed by representatives of standards developing organizations, government agencies, consumer groups, companies, and others. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested
the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards.

DIN

DIN stands for - Deutsches Institut für Normung e.V. (DIN; in English, the German Institute for Standardization) and is the German national organization for standardization and is that country's ISO (International Organisation for Standards) member body.

“DIN” and “mini-DIN” connectors, as well as “DIN rails” are several examples of older DIN standards that are today used around the world. However, there are currently around thirty thousand DIN Standards, covering almost all fields of technology. One of the earliest, and surely the most well-known, is DIN 476, the standard that introduced the A-series paper sizes in 1922 and this is now an international standard we all use each day.

DIN 41612

The connector system we are looking at here is known as DIN 41612 is a DIN standard for two part electrical connectors that are widely used in rack based electrical systems. The different versions of the connectors are lettered alphabetically and cover a range of applications from power, signal , RF and optical connections. The principle being that each half of the connector pair is placed on a component that can plug into another component. Standardisation of the connectors is a pre-requisite for open systems, where users expect components from different suppliers to operate together. The mostly widely known use of DIN 41612 connectors is in the VMEbus system. The standard has subsequently been updated as international standards
IEC 60603-2 and EN 60603-2.

Mechanical details:

The standard describes connectors which may have one, two or three rows of contacts, which are labeled as rows a, b and c. Two row connectors may use rows a+b or rows a+c. The connectors may have 16 or 32 columns, which means that the possible permutations allow 16, 32, 48, 64 or 96 contacts. The rows and columns are on a 2.54 mm grid pitch. Insertion and removal forces are controlled, and three durability grades are available. The types we are focusing on are primarily 48,64, and 96 way connector housings fitted with various pin configurations up to 96 ways.

Electrical details:

The headline performance of the connectors is a 2 amp per pin current carrying capacity, and 500 volt working voltage. Both these figures may need to be de-rated according to safety requirements or environmental conditions.

IEC 1076

The industry is responding with connector designs, which accommodate differential data transmission as well as single-ended systems to at transfer speeds from 100Mbits/sec. to 10Gbit/sec. speeds; fiber optic connectors up to 24 positions with 2.5Gbit/sec. to 5.0 Gbit/sec. per position; 5+2 and 8+2 row daughter card to backplane connectors with strip line shielding;
connectors for transmitting data rates exceeding 2.5Gbit/sec.; differential pair designs for speeds up to 2GHz accommodating rise time of less than 100ps; among others.

Board-to-board printed circuit connectors represent 74 percent of all demand for high-speed connectors. The majority are on a hard metric 2.0mm pitch and grid and include for example connector systems known as 4-row FB, 5-row FB, 5+2 HM, 8+2 HM, Z-pack SL, HM, VHDM, Z-pack HS3, HMHS, HM with fiber, among others. There are likewise 1.25mm pitch connectors such as Speed Pac, DensiPac, HSSDC, MetaGig, among others.

The leaders in high-speed board-to-board connectors are AMP Tyco with 22 percent market share, other providers are FCI, Molex, and Teradyne. Others include 3M, Hon Hai, Siemens, Harting, Erni, JAE, Hirose, and ITT Cannon.

Please note the images shown here are for illustration only and do not represent any support for any manufacturer in particular in any case.