Connector Corner

August 29, 2018

How to select a High-Speed Connector for Your Design Application

The design process of electrical applications includes numerous considerations, particularly while designing high speed networks. Many connector users may be unaware that various processes are considered, aside from merely assembling conductive wiring between two interconnects. Etching, tolerances, shielding, and more must be acknowledged while establishing high speed connections and ensure proper signal integrity.

The key to optimizing high speed connection is by ensuring minimal amount of signal loss. Once the bandwidth of the connection has been identified, the s-parameters can be further explored to fully understand the essence of the connection. Gathering a full understanding of these aspects gives the user and idea of the potential of the high speed connection. These s-parameters are a metric used by manufacturers to categorize the speed of connectors and should be highly considered. Careful attention should also be paid to the s-parameters in a time domain. This is a measure of the signal’s performance in relation to time.

Designers must also consider the importance of PCB termination options. Several options of many include: surface mount, press-fit, and paste-in-hole (PIH). Each has their own respective pros and cons. What makes press-fit terminations a solid choice is its durability. These rugged connections have a very secure connection to the PCB, but it poses challenges for the high speed connection that users are typically looking for. These high-density connectors make it difficult to route signals out of the PCB. These terminations styles typically require more layers in the PCB, which elongates the signal’s route, creates discontinuity for higher frequencies, and may inhibit the signal speed.

Surface-mount termination has a design that is more responsive to impedance matching. Designers have the option of establishing connections directly to the PCB. They use internal connections in the board called “buried vias” to improve the frequency response in such a way that is more effective than press-fit terminations. This method is more efficient for the high frequencies that experience loss in the press-fit option, but they are not nearly as durable. They typically require additional mounting hardware to establish the secure connectors that the press-fit alternatives could have provided.

Paste-in-hole terminations incorporate characteristics of the two previous styles. PIH styles use a plated pinhole for the contacts to be soldered into the PCB, Similar to the press-fit. The distinct difference between these two styles is the length of the pins in PIH types and the holes they utilize. The pins are much shorter, allowing holes to be drilled to reduce an excess stub on the signal. Signal stubs relate to the length of the signal over the transmission line. Unfortunately, the density of these styles inhibits communication with the PCB.

While deciding which style to use in a system, the contacts within the mating connector must be considered. There are several choices designers can make when determining a contact configuration. Much like the alternatives to termination, these options have their respective pros and cons. Edge mount connectors are one of such configurations. Narrow rods equipped with a spring guide the connection to the PCB, allowing greater continuity. However, shock and vibration pose a threat to the integrity of the connection under stress. Additional reinforcement may be required for security.

Press-fit connections are more commonly used for connections under stress that edge mount connectors may be unable to handle. It incorporates a similar rod and spring design like the edge mount connector, but offers additional features that give it the edge for high-stress scenarios. These connectors are extremely reliable because of the multiple points of contacts allowed for connection. Pin layouts, springs, and additional features create a tight connection and reduce the resistance to signal flow. Although the connection is tight, the length of contacts can cause issues. They sometimes exceed the length of edge mount connectors, which limits continuity in some cases.

The general ideas when establishing a high speed connection is that they need to provide a smooth, strong path for a signal to follow and a proper connector to establish the link between two points. Such an idea may seem relatively simple, but the importance of this idea remains critical. Opens in the circuit must be simply avoided. Getting into contact with proper suppliers is critical to the success of designing efficient networks and can greatly assist in the process. Proper education ensures minimal loss of single in the most effective methods.

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