Board to Board Connectors

Board to board connectors are used to connect printed circuit boards (PCB), electronic components that contain a conductive pattern printed on the surface of insulating base in an accurate, repeatable matter. Each terminal on a board to board connector is connected to a PCB. Products feature four basic mounting styles: through-hole technology (THT), surface mount technology (SMT), press-fit, and compression. THT mounts components on a PCB by inserting component leads through holes in the board and then soldering the leads in place on the opposite side of the board. SMT adds components to a PCB by soldering component leads or terminals to the top surface of the board. SMT components have a flat surface that is soldered to a flat pad on the face of the PCB. Typically, the PCB pad is coated with a paste-like formulation of solder and flux. Press-fit and compression-style board to board connectors are also commonly available.

Selecting board to board connectors requires an analysis of electrical and environmental specifications. Electrical specifications include insulation resistance, withstanding voltage, and contact resistance.  Insulation resistance is the electrical resistance between two conductors that are separated by an insulating material. Withstanding voltage is the maximum voltage a board to board connector can withstand without electrical breakdown. Contact resistance is the electrical resistance in ohms between contacts that touch each other. Environmental parameters such as vibration, humidity, temperature cycle, and durability are also important considerations when selecting board to board connectors. Vibration is measured at frequencies of 10 to 55 Hz with a single-amplitude of 0.75 mm for 2 hours in 3 different directions. Humidity range for board to board connectors may cover the non-conducting conditions of installed connectors in storage, shipment, or transportation.

Board to board connectors differ in terms of contact pitch, number of contacts, stacking height, contact style, plating materials, and housing materials. Applications and approvals are also important parameters to consider. In North America, board to board connector often bear marks from Underwriters Laboratories (UL) and/or the Canadian Standards Association (CSA). A board to board connector for the European marketplace should comply with the Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) directives from the European Union (EU). In terms of applications, some board to board connectors are used in power supplies, fan trays, lottery systems, personal computers (PCs), lighting systems, or gaming equipment. Others are used in heating, ventilation, and air conditioning (HVAC) systems; network equipment such as servers, base stations, hubs, and routers; and automotive applications.