electrical connectors

The electronic system is a hierarchical interconnection network, which can realize the communication between different electronic devices. To ensure the signal transmission and power distribution required for the normal operation of electronic equipment, multiple connectors are required. Electrical connectors are divided into three types according to their termination end:  board-to-board connectors, cables/wire-to-cable/wire connectors, and cables, and wires-to-board connectors.

Six levels of interconnection can usually be seen in electrical connectors.

• Level 0 is the connection between the basic circuit element and its leads, such as the connection between a semiconductor chip and a lead frame.
• Level 1 is the connection between the component leads and the printed circuit board (PCB), such as chip carrier sockets, dual in-line package (DIP) sockets, and switches.
• Level 2 is the connection between two or more PCBs. The main board-daughter board connection is typical.
• Level 3 is the connection between two sub-components, such as power supplies and associated sub-components.
• Level 4 is the connection from the main components to the input/output (I/O) ports of the entire system.
• Level 5 is the connection between physically separated systems, represented by the connection between a computer and a printer or other peripheral devices.

board-to-board connectors

Board-to-board connectors are used to connect PCBs without cables. Board-to-board connectors can save cable space, making it suitable for systems with limited space.

PCBs can be connected using parallel or vertical connectors, and connectors that connect two PCBs in a stacked configuration are called mezzanine connectors (this term is sometimes used to describe a vertical or side-by-side PCB layout). Usually used for motherboard-daughter board arrangement, where the focus is on parallel arrangement.

Specifications to consider when choosing a mezzanine connector include separability, mechanical requirements (such as stack height and tolerance), constraints (such as support, bracket, or chassis slot and frame), and installation type.

The detachability depends on many factors, such as whether the connector is detachable or permanent, the number of insertions and removals required during its service life, and the maximum and minimum insertion force required. The operating temperature and humidity should also be considered. EIA 700AAAB is the standard for mezzanine connectors.

A backplane is a group of electrical connectors connected in parallel so that each pin of each connector is connected to the same opposite pin of all other connectors to form a connector bus. Backplane systems are widely used in computer and telecommunication systems because of their flexibility and reliability. The backplane system is used to connect multiple add-in cards along a single backbone to form a complete backplane system. The signal generated by the transmitter reaches the receiver through multiple connectors.

Devices used in high-speed applications require backplane systems with high signal integrity. In the Gigabit backplane channel design, the backplane and related pin fields are indispensable parameters.

As the data rate increases, the backplane channel will attenuate the transmitted signal. The channel causes inter-symbol interference (ISI), reflections, and crosstalk. Crosstalk and reflections can introduce noise, reduce the signal amplitude and reduce signal edge rate, thereby further deteriorating channel jitter performance. At high data rates and distances between long channels, signal integrity becomes worse. Therefore, the connector of the backplane system should provide good impedance matching and shielding.

The connector should also withstand multiple insertions and removal cycles of the circuit board.

ables/wire-to-cable/wire connectors and cables

As the name suggests, a wire-to-wire connector connects two wires. One end of the connector is permanently connected to the wire, and the other end forms a separable interface, which can then be permanently connected using crimping or insulation displacement contact (IDC).

In the IDC method, the connection is made by inserting insulated wires into the slots of sharp metal beams. The sharp edges of the beam cut through the insulation and form a rigid metal-to-metal contact between the wire and the beam.

In the case of discrete wire connections, a crimping process is usually used. However, in the case of multi-core cable conductor termination, IDC is usually used. This is because IDC provides advantages in wire handling and mass terminations.

wire-to-wire connectors have a variety of housing geometries, including rectangular and circular polymer housings made of a variety of polymers, and metal housings mainly used in military applications.

wire-to-board connectors

As the name suggests, wire-to-board connectors connect wires/cables to the PCB. Wire connection is similar to wire-to-wire connection, and most board connections are two-piece connectors that are pressed in or welded. The mating interface of the detachable connection may be the same as the mating interface of the wire-to-wire connector from the same product series.

Although there are many applications for wire-to-board connectors, the trend is to use wire-to-board connectors or cable assemblies to take advantage of IDC.