Contact! Contact! Contact!

7 min read

One electrical component that is readily used and well-known to establish an electrical connection is a connector. Just as easy as that first line was read is just how easy many views purchasing connectors. The interesting part is that there is a component of the connector that may be overlooked but is crucial to defining the connectors capability. That component is called a “contact.” A connector’s contact plays a role in the choice of connector in that they come in various sizes, types, plating’s, layouts, and termination styles. These variables matter when deciding on the correct connector for your application.

What are Connector Contacts?

Connector contacts are the pins (male orientation) and sockets (female orientation) that create the electrically conductive element of a connector when properly mated with one another. When the pin and socket come into contact (excuse the pun) with one another, electricity can flow through the contact and the connector. Not all connectors come with contacts. There are some that are sold separately that allow a more ‘Do It Yourself’ model.

Since we are discussing electrical components, we know application plays a vital role in deciding the type of product required. When considering contacts, there are two standard applications that they will be designated for. The two types are Electrical and Signal. We know that electrical signals are used to transmit information from point A to point B. When said information is on a larger scale it has a known industry term called ‘data.’ However, signals communicate basic information and can be found in applications like pushbuttons or sensors. Signal contacts are generally small (either #16 or #20) since they are not transmitting much voltage and current. P

ower contacts are used to transmit voltage and current to operate other components and equipment. For some power applications, signal contacts can be used if the voltage requirement is small. When the application requires a more energy-intensive application, only power contacts are used. These contacts are larger sized contacts like #12, #8 or #4 (Note, just like wire and cable, the lower the number, the bigger size). These industrial contacts deliver much more amperage than those of signal contacts.

Selecting the Right Contact

Voltage and Current

Like many electrical related products, one of the first elements to consider when picking contacts are the voltage and amperage that will be running through the circuit. This is important because it will help determine what connectors and contacts that are most suitable to the application. The contacts play a critical part in the connectors performance as they contribute to the rated voltage and current allowance. This is important because as current moves through the connector, the contacts will generate heat. This is crucial to the overall capacity of the connector.

For example, if the connector is rated for a temperature of 105°C and it is going into a piece of equipment that produces 100°C. The heat produced by the contacts might exceed the connector’s rating thus damaging the connector and potentially the system its connected to. It is essential to verify that the connector can handle the power requirements, especially when heat generation is a factor.

Connector Layout and Size

The connector layout and size of the contact will also be key elements when it comes to deciding the type of connector and contacts. Applications tend to require a certain connector layout and number of wires. To fulfill the electrical requirements of an application one will verify the correct number of contacts based upon the layout and number of wires used. Each connector layout is designed for dedicated contact sizes.

When using contacts of the same size and capacity, the more contacts you use, the more heat they can produce. Finding the right balance between the current carrying capacity and electrical requirements is vital. By picking your connector layout first, this will help narrow down contact choices to determine the correct contact size. Wire size is a straightforward deciding factor. You would simply find out what wire size you are using, and this will determine which contact sizes are compatible for your application.

Contact Type

There are 3 main types of contacts.

  • Stamped
  • Formed
  • Machined

Stamped and formed contacts are often grouped together because they are similar, in their ability to be fed into an automated crimping machine. They are suited for high-volume production due to their easy manufacturing process. Machined contacts are usually present for power applications and have low volume production due to their manufacturing process. They are more durable and suitable for heavy usage. The choice for which contact type to be used will come down to your personal preference and crimping method.

Contact Plating

Another key element to contact consideration is it is plating. The plating of a contact affects both durability and connectivity of a connection. One of the most popular forms of plating is ‘Gold Plating.’ Gold has excellent conductivity and good lubricity making it able to withstand extensive mating cycles. You will see gold plating for smaller contacts, under 1A and 5mV (#16 and #20), with at least 1.4 microns of gold. One disadvantage is its excessive cost, which is why you will not see it much in larger contacts.

For slightly bigger contacts, you will find them ‘Tin-Plated.’ Since bigger contacts have a larger surface and gold is more expensive, tin is used as a cheaper option that performs quite well for low-vibration and static environments. One other plating you may see is ‘Silver-Plating.’ This plating is found in size #12 and #8 contacts, providing a good balance between reliability and cost.

Contact Termination

One of the last things associated with deciding on the type of contacts are their termination methods. The type of termination method used has impact on your application and system processes. The two most common types of terminations are crimp and solder.

  • Crimp Contact – is terminated to a wire via a dedicated crimping tool. Upon termination, an insertion tools are normally used to insert the crimped contact into the connector. This crimped contact can only be removed using a specialized removal tool unless it is a special removable crimp contact, which permits a rear or front release without a specialized tool. One benefit of these contacts is their ability to be repaired onsite due to their removal capability.
  • Solder Contact – is terminated to a wire using solder. These contacts cannot be removed because they are bonded into the insulator. This termination is not easy to repair in the field. However, it is easier to seal against the entrance of moisture.

If you need contacts and associated accessories, MISUMI has all your contacting needs, with many contacts in-stock including Contacts (Pins & Sockets), Crimping & IDC Tools, and Terminal Removal Tools.

About the Author

Patrick Teagues

Patrick is a Product Development Analyst at MISUMI. He holds a bachelor’s degree in Biological Science, a minor in Chemistry, and a Master’s in Business Administration from Northern Illinois University. He is a Certified Six Sigma Green Belt and has worked in chemical manufacturing for seven years.

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