PC Card Connectors Information
PC card connectors are used to connect PC cards, CompactFlash cards, and other devices to computers. The PC card form factor is defined and maintained by the Personal Computer Memory Card International Association (PCMCIA), a U.S. computer industry trade organization. Known originally as PCMCIA or PCMCIA cards, PC cards were designed for computer storage expansion. They are now used as network cards, modems, and even hard disks. PC card connectors are not just designed for PC cards, however. They include devices for use with CompactFlash and internal computer electronics. CompactFlash® (CompactFlash Association) is a very small, removable, mass storage device. At half the size of an ATA Flash card, CompactFlash cards can have extremely high MB capacities. Internal computer connectors are PC card connectors for connecting devices inside computers. Examples include power connectors, RAM memory slots (SIMM, DIMM, etc.), LEDs, and processors.
Examples of PC cards. Image Credit: GeniusForHireProject / CC BY-SA 4.0
PC card connectors were originally designed to add storage to a computer, but the creation of a usable general standard for notebooks, led to many kinds of devices being made available based on the form factor. These include network cards, modems, and hard disks. There are two different versions of the PC card: the 16 bit and the 32 bit. The 32 bit includes DMA or bus metering while the16 bit does not. This technology has been superseded by the ExpressCard in 2003.
Today, alternative storage expansion technologies consist of USB Connectors.
Types of PC Card Connectors
There are four basic types of PC card connectors. Each corresponds to a PC card.
- Type I connectors are for PC cards with dimensions of 54-mm x 85.4-mm, and that can be up to 3.3-mm thick. Normally, these devices are used as memory cards (i.e., RAM, ROM, and Flash RAM).
Type I. Image credit: ITT Cannon
- Type II PC cards are also 54-mm x 85.4-mm, but can be up to 5.5-mm thick. Common uses for these cards include I/O devices such as ax modems, LAN adapters, and non-rotating mass storage products.
Type II. Image credit: Delphi
- Advanced telecom computing architecture (ATCA, AdvancedTCA) connectors are used to connect or interface AdvancedTCA devices and boards to systems or motherboards.
Image credit: Computer Desktop Encyclopedia
- CompactPCI (cPCI) connectors are used to connect or interface CompactPCI devices and boards to systems or motherboards.
CompactPCI. Image credit: Eurotech
The contacts of PC card connectors are conductive elements in a termination assembly. They mate with corresponding elements in order to transfer electrical energy.
Contact Plating
Plating, the overlaying of a thin metallic coating on metal components, improves conductivity and facilitates soldering. With PC card connectors, choices for contact plating include:
- Copper plating- Copper-plated contacts are commonly available. They are difficult to create since copper is an active metal.
- Gold plating- Gold-plated contacts provide a more reliable electrical connection. These are more expensive than silver-plated or copper contacts, and are generally offered as an upgraded connector.
- Nickel plating - The connector is available with a nickel-plated contacts.
- Silver plating- Silver plating is commonly used in electronics. Silver can be used for plating copper, as its electrical resistance is lower, more so at higher frequencies due to the skin effect.
PC Card Specifications
- Number of contacts- The number of contacts is the number of conductive elements that mate with a corresponding element to provide an electrical path.
- Current rating - Current rating is the maximum, recommended, continuous flow of electrical current.
- Contact resistance- Contact resistance is the measurement of electrical resistance of mated contacts when assembled in a connector under typical service use. Electrical resistance is determined by measuring from the rear of the contact area of one contact to the rear of the contact area of its mate (excluding both crimps) while carrying a specified test current. Overall contact resistance would be the wire-to-wire measurement.
Standards and Associations
Personal Computer Memory Card International Association (PCMCIA)- The PCMCIA is an industry group which promotes standards for both memory and I/O integrated circuit cards. PCMCIA Standard 2.1 was published to ensure standard attachments for any peripheral device that follows the standard. This association dissolved in 2009 and its activities are now managed by the USB Implementers Forum.