Image credit: Newark/element14; Omron Electronic Components LLC; Samtec Inc.
Board to board connectors are used to connect printed circuit boards (PCB). Each terminal connects to a separate PCB.
How do Board to Board Connectors Work?
Board to board connectors connect PCBs without the use of wires. They are typically made of plastic and have metal connects. Board to board connectors consist of two connectible parts. One part, which typically has pins, attaches to one PCB while the part with receptacles is mounted to another PCB. The circuit boards are then connected by mating to two parts of the connector.
The increased height of some board components may necessitate more space between stacked PCBs. For this reason, some board to board connectors are taller than others to facilitate this greater space.
Board to board connectors are manufactured using either through-hole technology or surface mount technology (SMT). Both mounting schemes have different uses and advantages.
Through-hole connectors make connections using leads or contacts that are inserted through holes drilled in the PCB. The leads are then soldered to pads on the opposite side of the board to complete an electrical connection. Through-hole connectors are useful in making strong vertical connections between layered boards. They are also widely used in prototyping because of their compatibility with breadboards.
Surface mount (SMT) connectors are mounted directly on top of the PCB. They may have short leads or pins that do not pass through the board, or no leads at all. SMT components can be manufactured to be much smaller than through-hole ones and are generally cheaper to buy and produce. However, they cannot be used on traditional breadboards and their solder connections are generally weaker than through-hole connections.
Left to right: through-hole connectors, SMT component on a PCB. Image credit: Samtec; Custom electronics
When selecting board to board connectors, buyers may specify information about the product's type, contacts and features. Many of these specifications are determined by the PCB the connector is designed to operate with.
A board to board connector's type is determined by its header, which is the plastic base or mounting plate to which the contacts are attached. Box header connectors feature a header which completely surrounds its contacts, whereas a pin header's contacts are exposed.
A box header (left) and pin header connector. Image credit: made-in-china.com; Warf
Board to board connectors are available in two different gender configurations. Male connectors, sometimes called plugs, consist of a protrusion which fits into the female connector, sometimes known as a receptacle. Additionally, the connector may feature different geometry. A straight connector has pins or contacts aligned at the top or bottom of the connector, whereas a right angle connector has contacts mounted on its sides.
The GlobalSpec SpecSearch database also contains information about a connector's contacts, including rows, pitch and plating.
Depending on the PCB arrangement, a connector may feature pins arranged in one or two rows. A connector's pitch refers to the distance between its pins. A larger contact pitch describes a lower connection density (less pins or connections per area). Pitch affects arcing, which occurs when two conductors are close (pitch is low), causing interference. Common connector pitches vary from under 0.5 mm to over 5 mm.
Because connector contacts are conductive elements that transfer electrical energy, they may be metal plated to enhance their connection abilities. Common metals include copper, gold, nickel and silver. While gold plated contacts make for a more expensive connector, they provide superior electrical connection. Silver and copper also feature lower contact resistance.
Board to board connectors may include a variety of special features.
Connection features apply to the product's connection method. Locking connectors can be locked to prevent unauthorized disconnection. Quick connect products can be connected and disconnected quickly, typically using a twist and seat contact method. Press-fit connectors do not require soldering; instead, the pins or leads are pressed into the PCB.
Environmental features described the degree to which the device is protected from chemicals, liquids or other outside factors. Manufacturers may provide connectors that are hermetically sealed or resistant to chemicals, oil or water. Some connectors are specially manufactured for cryogenic (subfreezing) use.
Filters are installed into connectors to reduce electromagnetic and radio frequency interference.
Medical connectors conform to rigorous safety standards, including prevention of inadvertent plug disengagement and increased shock rating.
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