Where Have All the Connectors Gone?

Have you ever thought about the diverse types of connectors used in today's computers, and exactly where they're used, and in what numbers? Here's a quick look at the state of today's connector products, including cable assemblies and backplanes.

By: Ken Fleck


•Millions of All Types
•Discerning the Application
•The Big Picture
•Oddball Connectors
•Standards Rule
•The List Goes On
•Cable Assemblies Go Big Time
•What's the Distinction?
•Those Big Backplane Apps
•The Big Nine

There are over 50,000 part numbers of separable interconnects used in today's computer equipment. The value of these connectors--calculated on a worldwide basis--was over five billion dollars last year alone.

Printed circuit connectors for computer equipment, for example, accounted for a whopping $1.9 billion worldwide. Similarly, I/O connectors accounted for $1.1 billion worldwide. Insulation displacement connectors (IDC) accounted for a healthy $403 million.

Even backplanes, which are used in larger computers, and can be considered interconnect products (replete with separable connectors), totaled a rather hefty $580 million.

Millions of All Types

Similar numbers for other types of separable interconnect products are equally impressive. For example, IC sockets (including SIMM and DIMM single- and dual-inline memory module interconnects) totaled over $400 million worldwide. Fiber optic connectors tallied an impressive $55 million. And, connectorized flex-circuit sales rang in at $125 million worldwide. Filter connectors tallied up an additional $87 million.

Did you know there are 72 types of IC sockets utilized in computer equipment? Those with the highest volume sales include SIMM 72, DIMM 168, DIMM SO72, and DIMM SO144 types, as well as those used for Intel Socket 8 and Socket 7 applications. But other categories include land grid array (LGA) and plastic leadless chip carrier (PLCC) sockets.

There are also PGA burn-in types, small outline plastic (SOP) and thin (TSOP) burn-in sockets, as well as QFP burn-in, and BGA burn-in types.


Discerning the Application

Cable assemblies for computers, which are typically application-specific, accounted for more than one billion dollars worldwide last year. At the same time, a large number of cable assemblies--such as RJ-45 patch cords, modem cables, network cable assemblies, transceiver cable assemblies, and the like--in which the application is becoming more difficult to separate between computer and datacom equipment. Worldwide, these account for $2.7 billion.

Desktop machines use multiple connectors for things such as ISA and PCI buses. There are also unshrouded headers, as well as sockets for Socket 7 or Slot 1 applications. There are also numerous D-subminiature types (often called D-subminis), IDC ribbon types, and circular or mini-DIN connectors.

Today's desktops may also use dedicated connector types for SCSI connections, RJ-11 and RJ-45 data interconnects, and for power. These machines also include scads of DIP, PLCC, PGA, SIMM, DIMM, among other connectors.


The Big Picture

Let's try and get a big picture for connectors going into computer equipment. Keep in mind there are 254 design types of printed circuit connectors utilized.

Those with high volume are ISA, PCI, board-to-board card-edge, wire-to-board card-edge types, and 2.54 mm pitch headers and receptacles. But, there are also DIN, HDI, HPC, and HD+ application types, as well as 2.0 mm pitch (four rows), 2.0 mm pitch (five plus two rows), 2.0 mm pitch (one to two rows), 0.8 mm pitch, and 1.27 mm pitch types.

There are even 11 styles of circular connectors typically used in today's computers. High volume types include circular DIN, audio, and earphone plugs.

There are 134 types of I/O connectors used too. High volume types include D-subminiature board-mount types, D-sub crimp styles, D-sub IDC connectors, filter-equipped D-subs, and high density D-subminis. These high-density connectors find application as docking connectors, for Centronics parallel printer ports, and for various SCSI applications such as SCSI I, II, III, and so-called ultra-SCSI connections. These connectors are also used to support IEEE-1284 ports, and, increasingly, Universal Serial Bus (USB) peripherals.

There are 19 design types of IDC connectors used in computer equipment. Those with the highest usage include pin headers, sockets, card-edge types, and printed circuit board (PCB) types. Other heavily utilized IDC types are DIN, D-sub, SCSI, and high-speed transmission connectors.


Oddball Connectors

There are also 27 design types of coaxial cable connectors used by OEMs in today's computers. However, none of these coax connectors represent high volumes in the computer industry. Most are used for RF applications.

On the other hand, there are 39 design types of fiber optic connectors, couplers, and adapters typically used in today's machines. Similarly, there are 20 design types of connectorized flex circuits.

Also, there are eight types of filter connectors widely used, but the only high-volume design type is the D-submini. None of the above are high volume items.


Standards Rule

The computer industry has spurred the establishment of many standards, both inside the box as well as for cable connection. For example, cable connection standards now include the ubiquitous 9-pin DB9 type (used for serial mouse and printer connections, as well as for monochrome monitors). Then there's the HD15 type widely used for VGA and SVGA video monitor connections.

Similarly, the ubiquitous 15-line DB15 is used for joystick and Mac Video connections. The very common 25-pin DB25 type is typically used for a PC's serial and parallel IEEE-1284 connections. Likewise, the DB37 serves serial I/O, CD-ROMs, and Bernoulli Box interconnects. The DB50 is used for SCSI I; the half-pitch DB50 supports SCSI II. The half-pitch DB68 is used for SCSI III.

In the lab, the Centronics-24 supports IEEE-488 general-purpose instrumentation bus (GPIB) applications. The Centronics-36 serves parallel and IEEE-1284 applications. The Centronics-50 also can be sued for SCSI I.

The half-pitch Centronics-36 can be used for IEEE-1284 too, and parallel Type C half-pitch Centronics-50s are used for SCSI and IBM ThinkPad SCSI connects. The half-pitch Centronics-60 supports IBM RS/6000 and ThinkPad notebook SCSI interconnects. The half-pitch Centronics-68 is also used in the Model RS/6000. The Very High Density Centronics-68 supports Ultra SCSI separable interconnection.


The List Goes On

But wait, there are more! The IDC40 socket is typically used for internal IDE hard disk (HD), CD-ROMs, and tape drives. Likewise, the IDC34 socket is used for internal floppy and tape drives. The IDC34 edge-card is used with internal five-inch and three-inch floppy and tape drives. The IDC50 header supports internal SCSI drives.

Also, the half-pitch 68-line DB68 types are used for internal SCSI III drives, and IDC50 SCSI connectors are used for internal terminators. The HDI30 is used in Apple's PowerBook notebook computers. DIN5 types support PC keyboard connections and were also used in the Apple IIc serial applications.

The MiniDIN3 is used for AppleTalk (and Localtalk) interconnections. The MiniDIN4 is used in Apple's ADB port for its mouse and keyboard. Similarly, the MiniDIN6 is used in IBM PS/2 keyboards and mice. The MiniDIN8 is sued in the very popular Hewlett-Packard Image/LaserWriter and serial printer applications, as well as the HP DeskWriter and modems.

The MiniDIN9 is used to support the so-called bus mouse. The 13W3 is used in the popular Sun Workstation monitor. Mini-coax BNC coaxial connectors are used in its RGB monitors.


Cable Assemblies Go Big Time

The big picture for cable assemblies going into computer equipment reveals no less than 25 design types. High-volume designs include keyboard cable assemblies, keyboard extensions, mouse/keyboard extensions (such as the PS/2 DIN type), and IDE ribbon, SCSI internal ribbon, and floppy drive ribbon assemblies. Other ribbon cables serve internal serial connections, and monitor-cable extensions.

Cables assemblies also include those with DB15 connectors, and BNC monitor video combinations. There are others too, such BNC monitor video types, and printer cables using parallel DB25 connector types. Cable assemblies are also used to support enhanced parallel (IEEE-1284) ports, external serial devices, and external SCSI II, III, and ultra-SCSI drives. There are also cable assemblies for the IBM data connector, disk drive round-to-flat, and USB.


What's The Distinction?

There are 33 design types of cable assemblies in which the distinction between the application is difficult to determine (is it in the computer OEM or datacom OEM realm?). High volume types that fall into this grey area include RJ-45 shielded and non-shielded patch cords, RJ-45 shielded network assemblies, RJ-45 non-shielded network types, RJ-45 enhanced/plenum network types, and RJ-11 non-shielded network assemblies.

Modem cables include DB9 and DB25 types, balun, BNC LAN patches, BNC LAN network types, BNC LAN network combinations, transceiver cable assemblies, IBM data connectors (for Token Ring networks), and IBM data connector combos. There are also cable assemblies for V.35 modems, LAN backbone coax applications, fiber optic FDDI applications, and multiple fiber applications--as well as application specific assemblies.


Those Big Backplane Apps

Let's look at backplane applications in computer equipment. Right now, there are 29 designs of backplanes. The high volume designs include VME, Multibus I and Multibus II, STD Bus, DIN, card-edge, 2.54 mm, 2.0 mm, and flex circuits, but there are others.

In terms of interconnect devices, there are at least 61 discernable design types. The high-volume designs include SCSI II and SCSI III terminators (active), all internal terminator types, printed circuit connectors incorporating ICs, PCMCIA connectors for computer slots, and multi-chip modules/land grid arrays (LGAs).


The Big Nine

I find it useful to consider that there are nine subdivisions of the computer industry that use interconnect products.

These are:

(1) Desktop and desk-side machines: This definition includes the standard PC for home or office use. It also includes the sub-$1000 PC as well as the so-called Thin Client or Net PC.

(2) Notebooks: This class is defined as being 2.5 in. to 3.5 in. thick with a weight of four to eight pounds. These systems have most of the characteristics of desktop systems.

(3) Subnotebooks and handhelds: These computer systems are defined as being 1.5 in. thick or thinner, and weighing in under three pounds. The class includes ultra-thin notebooks.

Also included in this category are handheld devices such as the popular Palm Pilot personal digital assistants (PDAs) and Windows CE (and other operating system and GUI) handheld PCs, or HPCs.

(4) Workstations: The workstation is defined as a higher powered machine than a desktop. Computers in this category include those for custom applications such as graphics processing, and CAD and CAM workstations.

(5) Multi-user systems: These are defined as servers. The category includes all mainframe machines, and so-called super computers.

(6) Storage: This area includes rigid disk drives, RAID (redundant arrays of inexpensive disks) array boxes, external disk drives, CD-ROM servers, and tape drives.

(7) Monitors: This class includes CRT monitors as well as all other display devices.

(8) Printers: Includes all types of printers and output devices, such as film recorders.

(9) Peripherals: These includes devices such as the common mouse, as well as keyboards, switches, and other input devices.