An electronic system is a hierarchical interconnection network that enables communication among different electronic devices. Several interconnects are required for signal transmission and power distribution to ensure the correct operation of electric products. Electrical connectors are classified into three types with regard to their termination ends: board-to-board (B2B) connectors, wire-to-wire (W2W) connectors, and wire-to-board (W2B) connectors. The connectors are also classified based on the application like signal connectors, RF connectors, and power connectors. Signal connectors can be further classified as general-purpose, low-frequency, and high-frequency connectors such as USB, PCIe, etc.
Increasing signal speed and switching frequency demands stringent requirements from connectors. Primary issues while dealing with connectors are electrical length, need of a larger assembly area, compatibility with new technologies, and reliability.
A connector introduces an extra electrical path that can lead to added propagation delay and electrical noise, such as crosstalk.
A connector also raises concern for reliability, because degradation of the contact interface can lead to an increase in contact resistance, resulting in signal distortion, heating problems, and power loss. These losses increase due to contact resistance, which depends on the material properties of the connectors, environmental conditions, and mode of operation.
Additionally, since a connector occupies more area than a simple solder or adhesive, the use of connectors might be difficult in applications that have limited space.
When mounting a connector, it is important to know the influence of forces such as engagement, disengagement, and mounting methods such as pressing or soldering. The three mounting methods (shown in the above image) are frequently used in PCB applications. First is the press-in method, which means that the PCB connector with press-in legs is inserted into the defined plated-through holes. Compared to the traditional soldering method, press-in mounting guarantees the same electrical and mechanical performance. It also makes a more secure contact and is easier to assemble than with soldering.
Placing connectors on one edge of the board makes it much easier to hold them on the same reference potential. This is important for boards with high-frequency components that will not be shielded.
Some designs require connectors to be placed on different sides of the board. In such situations, it's critical to avoid placing high-frequency circuits between any two connectors. If it is not possible to avoid placing high-frequency circuits in between connectors, a metal enclosure and chassis ground filtering are employed to prevent the board from driving common-mode currents onto the connected wires.
Don't use a matched termination unless the rise time has already been slowed as much as possible and the trace length has been shortened as much as possible. Matched terminations are undesirable because they use more power and make it difficult to control rise times. However, they are important for signal integrity and EMC when the trace delay is more than the transition time. You check out our trace width calculator which is capable of calculating trace width, the amount of trace current and the temperature rise.
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