Advances in composite manufacturing for enclosures and EMIshields are enabling companies to offer significant advantages
Composite materials are traditionally designed and used for structural applications on account of their mechanical properties. However, composite materials are increasingly being used in non-structural applications, such as electrical and electronic (E&E) applications. Examples include interconnections, electronic enclosures, printed circuit boards, interlayer dielectrics, electrical contacts, connectors, heat sinks, and housings. Moreover, for many of these applications, structural composite materials that are multifunctional are increasingly needed, due to the demand for smart structures and the importance of weight saving. 

 

Electronic enclosures

Despite a modest global growth forecast of only around five percent over the period 2015-2019, the electronic enclosures market is undergoing change. Increased demand from developing countries such as China and India is leading to a technological shift away from metallic enclosures towards those made from composite materials.
Steel, aluminum, or nickel alloys have been first choice for electrical enclosures for decades, thanks to their rigidity, high impact resistance, and wide operating temperature range. For industrial applications, these metals provide excellent protection against solvents, hydraulic oils, alcohols, and gasoline. Their electrically conductivity is key for EMI-sensitive applications. However, they are gradually facing competition from new, composite enclosures based around glass fiber and carbon fiber.

 

Advantages of composite enclosures

One reason why composite enclosures are being specified is their lighter weight: a carbon-filled Polyphenylene Sulfide (PPS) enclosure can be 40 percent lighter than an aluminum one. This is particularly important for military, automotive, and aerospace applications, as well as to ease the installation and handling of large enclosures. Another reason is increased design flexibility; the wide choice of both polymers and filler materials gives designers great freedom to customize the characteristics of a composite to fit the application. 
Advantages extend to the manufacturing process. A metal enclosure’s shape must be stamped; an expensive and time-consuming process, particularly for complex shapes. Advanced composite molding technology, on the other hand, allows the creation of complex three-dimensional shapes. Selective metallization can add circuit traces and shielding, while antennas can even be embedded into the enclosure to save weight. For low-volumes or prototypes, composite enclosures can take advantage of 3D printing technology.

 

EMI performance

Electrical device manufacturers have traditionally turned to metallic enclosures to ensure electromagnetic compatibility (EMC): thus reducing emissions and protecting against external noise. The best performance is generally provided by metal enclosures. However, their effectiveness can be reduced by galvanic corrosion and oxidation. Step forward composites: carbon fibers or other conductive fillers can be added to make the material conductive, resulting in enclosures with EMI reduction of up to 40dB over a wide frequency range, which may be fine for many applications. Moreover, long carbon fibers can result in a composite strength comparable to that of metal.

 

Heat dissipation

Of course, non-metallic enclosures are poor conductors of heat, although this can be an advantage of disadvantage depending if heat needs to be retained or dissipated. But composite enclosures offer a variety of solutions for applications where heat dissipation might be an issue, such as heat sinks, thermoelectric cooling, and heat pipes.

 

An Australian leader

In the Asia-Pacific region, Composite Materials Engineering (CME) is a specialist in the advanced composites business, manufacturing all of its products at its headquarters in Melbourne, Australia. The company formulates, manufactures and compression molds long glass fiber composite materials.
According to CME, advanced composite materials are ideal for electrical and electronic applications because of their high dielectric strength and arc resistance properties. In combination with an elevated continuous operating temperature, advanced composite materials are ideal to act for a wide range of electrically insulation applications. CME’s advanced composite materials find end use applications in lamp housings, terminal boxes, electrical enclosures, plugs, sockets and components for distribution of energy.

 

Written by Denzil Walton

Denzil Walton is a technical copywriter, editor and conference reporter. He has over 30 years’ experience writing on a variety of industrial and high-tech topics.

 

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