Material Considerations: Cable Assemblies for High-Temperature Applications

As more applications involve high-temperature systems, resin manufacturers are formulating more common resins like TPU to survive in higher temperatures.

By iCONN Systems

Many transportation, marine, medical, and other outdoors applications require equipment rated for sustained performance at elevated temperatures. For transportation applications, heat is generated within the operations of the vehicle, including combustion, engine, and exhaust systems in fossil fuel vehicles. In electric vehicles, battery management and charging systems generate heat. Additionally, all vehicles are exposed to high temperatures in hot environments. The components that serve these applications must be selected carefully to ensure they can endure fluctuating and high temperatures.

The exact performance attributes required vary by application, but operating temperatures typically range from 60 °C (140 degrees °F) to 260 °C (500 °F). Some applications expose the connector assembly directly to a flame for a specified period of time, such as firefighter wearables that must survive high heat. Typically, resin choices have been limited to select families, but recently resin manufacturers have started to formulate more common resins like TPU to survive in higher temperatures as well. This offers many new possibilities for the design of connectors and cables.

Heat-resistant cable assemblies

All aspects of a molded cable connector assembly must be evaluated for high-temperature applications. These typically include:

• Wire/cable insulation and jacketing used in the assembly
• Electrical insulation material used to isolate the contacts/terminals
• Overmold material used to create the transition from the electrical insulation to the cable
• Mechanical hardware components that provide the attachment means for the connector
• Sealing elements that provide additional environmental and ingress protection

Until recently, jacketing materials were very limited for high-temperature applications. Many materials needed to be processed through a secondary application after being extruded, such as an e-beam machine.

However, resin manufacturers have invested in research and development that has led to new innovations in materials, including new resin products like a TPU rated to 125 °C (257 °F). This resin does not need to be processed through an e-beam machine, so cost and lead-times are more attractive.

Insulation materials

In the construction of cables, the wire elements are typically encapsulated in a resin jacketing to help protect the cables. The materials used for high-temperature electrical insulation can vary depending on the application. Plastics typically used for the mid- to high-temperature range are mineral- or glass-filled PA family of resins and glass-filled PBT family of resins. The high- to very high-temperature range requires higher-performing polymers, including the PPSU family of resins and the LCP family of resins. The PPSU and LCP resins require specialty molding parameters and equipment, which are all provided by iCONN as a complete solution package to our customers.

Overmold material

Overmolding is a strategy that helps protect cable assemblies by encasing cables at juncture points with a resin casing. High-temperature overmold materials vary but tend to assume a rigid form as maximum temperature requirements increase. One strategy is to design and manufacture connectors and cable assemblies for demanding and high-heat applications using overmolding resins from the glass-filled PBT family of resins and glass-filled PA family of resins. This protects the connections with durable and flexible material that also maximizes the water ingress protection characteristics of the design.

Protection for mechanical hardware components

Coupling devices and panel mounts for high-temperature applications should be constructed of either electroless nickel-plated brass or stainless steel. These durable materials have an extremely high melting point and typically outperform any of the plastics within the assembly.

Another strategy to enhance waterproofing and protection is to integrate O-rings into connectors and cable assemblies to add additional sealing properties to connections in an application that may be exposed to high temperatures, dirt or dust, and moisture. Those O-rings are typically constructed from silicone with an operating temperature of over 200 °C (392 °F). Silicone’s melting point is much higher, but if an O-ring loses its durometer, the seal could be compromised.

When specifying a cable assembly for a demanding application that will operate in challenging outdoors, transportation, or environmental conditions, it’s essential to design protection into the system. Recent advancements in materials science offer new products that are ready to protect interconnects and electronic systems from the everyday challenges that impact many critical systems. Working with a skilled and innovative supplier to specify and design the ideal components that support your application in any condition is a first step in the design of a successful application.

To learn more about solutions for harsh environment applications, visit iCONN Systems.

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