Principle and application of wire-to-board connectors

As we know,the wire to board connector is one of the main type of the connectors.but how to know more about the details for wire to board connector,just let me introduce the Principle and application of wire-to-board connectors.

This arcticle is mainly introduced from the following aspects：

• What's unique about wire-to-board connectors?

• Does the number and shape of wires matter for the connectors?

• What's the factors to Consider in Designing Connectors?

What's unique about wire-to-board connectors?

Printed circuit boards (PCBs) in systems and electronic devices need to be connected to the outside of the substrate when receiving/transmitting the output power of signals. In many cases, "there is a certain distance between printed circuit board and substrate" requires wires to connect. Long-distance connections can be achieved by soldering wires to substrates. However, for functional considerations usually use multi-needle-to-plate connectors to connect. A kind of

The structure of the wire-to-plate connector is simple: the electrodes (contacts) are placed in the housing (shells). There are two types of contacts: rod or sheet "plugs" and "sockets". Completely squeeze the plug into the socket and cover it to achieve "pairing". (Fig. 1) Generally speaking, the socket is connected to the wire, the plug is connected to the substrate, but this can be adjusted according to the usage. The connection between wires and contacts is usually realized by "pressure bonding" technology, such as crimping terminals. Pressure welding can be used to connect wires and contacts. Pressure welding technology is used for low current connection to simply connect insulating wires to contacts to allow full connection. Although this method is convenient, its durability may be reduced. The above two technologies can avoid overheating caused by soldering technology and protect the connection from damage. In addition, the air-tight connection area can keep the connection stable because it will not be exposed to the air.

Does the number and shape of wires matter for the connectors?

When choosing a suitable connector, the number and shape of the connecting wires must be considered first. However, the current and contact pressure in the circuit must also be considered. Circuit current determines the diameter of the wire The diameter of the wire determines which connector is the best choice. There are several types of contacts that can be selected based on different wire diameters. Contacts need to conform not only to the conductor diameter but also to the diameter of insulating compound. When choosing contact plating, we need to know the current and contact pressure data and the environment of the connector. Different types of connectors are suitable for different currents and contact pressures. Generally speaking, "low current, low pressure connectors use high stability of gold plated sheet." Other types of connectors use cost-effective tin plated sheet. Needle count is also a factor to be considered. The unexpected high energy is produced when the connector is inserted and unplugged. This is because each contact produces energy. Therefore, the higher the number of needles, the greater the energy produced. In the case of gold plating, the contact pressure of each contact can be reduced but not in the case of tin plating. Tin plating requires relatively high contact pressure, so the maximum number of needles allowed is less than gold plating.

What's the factors to Consider in Designing Connectors?

Factors to Consider when Designing Connectors

Because the purpose of the connector is to connect, it is easy to design. A kind of despite the simple structure of connector components, caution is still needed in design. For example, when the current in the wire is high, it needs to be reduced because each wire will cause temperature to rise. (Fig. 4).

Figure 4: Reduction Legend Based on Needle Number

A kind of human errors should also be taken into account when designing connectors because manual operation is required especially when manufacturing line-to-board connectors. Error insertion is a typical human error: the user connects the connector to the wrong location or the wrong direction of the connection. Users often misrecognize connectors or force backward insertions and are unaware of errors. Therefore, many connectors are designed to be asymmetrical, and can only be connected in one direction. This method can avoid wrong insertion, but more importantly, the structure design can minimize the probability of human error. For example, "multiple connectors should not be connected to a single substrate when designing" because this can lead to wrong insertion. If the same type of connector has to be connected to a single substrate, it needs to be marked with different colors or keying plug to prevent misinsertion.

By understanding the principles of the wire to board connectors, I believe that  can help us better understand the wire-to-board connectors,also for the other connectors,like automobile connector, RF connector,etc.At the same time,how to choose the right connectors, and how to install them.