Figure 1: Composites allow circuit traces, terminals, and
antennas to be incorporated during fabrication.
(Image courtesy of TE Connectivity.)
Long thought of as a sleepy backwater where designs remain unchanged for years or even decades,
electronic enclosures might be the epitome of a mature
market. TechNavio’s analysts forecast the global market to
grow at a CAGR of only around 5 percent over the period
Even so, the winds of change are blowing in the
enclosures market. Increased demand from developing
countries such as China, Brazil, and India is one of the
major drivers of growth. In technology, the biggest shift is
away from metallic enclosures towards those made from
Composite Materials Make Gains
Metallic materials such as steel, aluminum, or nickel
alloys have long been a popular choice for electrical
enclosures. They’re rigid, have high impact resistance, and
can be used over a wide range of operating temperatures.
For industrial applications, metallics provide excellent
protection against hydraulic oils, gasoline, solvents, and
alcohols. And, of course, they’re electrically conductive,
which is key for EMI-sensitive applications, but a
disadvantage for wireless applications since they require
an external antenna.
But as they say, “out with out, in with the new.”
Although steel and aluminum are well understood and
have a long history, composite enclosures are gradually
replacing metallics in many applications.
A composite is a combination of a high-performance
engineered plastic (polymer) plus a filler material.
For electronic enclosures, the plastic is likely to be
a high-temperature moldable thermoplastic such as
Polyphenylene Sulfide (PPS), Polyetherimide (PEI),
Polyether Ether Ketone (PEEK), or Liquid Crystal
Polymer (LCP). Each one has different characteristics; the
choice of thermoplastic depends on the required operating
temperature and the likely fluid exposure.
The filler material adds structural strength and
allows modification of the parameters to give the best
combination of weight, electrical, mechanical, and
environmental performance in the target application.
Filler choices include glass fibers, and various forms of
carbon such as fibers, microspheres or nanotubes.
Composite materials are used in many fields apart from
enclosures, of course. In medical equipment, for example,
carbon fiber composites are used to make microelectrodes
and micro-biosensors. At the other extreme, carbon
nanotube-reinforced polymers have been used as
structural components in military aircraft.
Advantages of Composite Enclosures
Why are composites an attractive option?
Lighter weight is one key reason. A carbon-filled 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.
The wide choice of both polymers and filler
materials gives the designer great freedom in tailoring
the characteristics of a composite to the application.
Figure 2 compares the characteristics of some common
A metal enclosure’s shape must be stamped, which is a
costly and time-consuming process that often cannot be
readily adaptable to intricate shapes.
For composites, advanced molding technology allows
the creation of complex shapes that include standoffs,
integrated connector shells, partitions, and other three-dimensional features. Selective metallization can lay down
circuit traces and add shielding; even embedded antennas
can be integrated into the enclosure to save weight. For
low-volume or prototype builds, composite enclosures can
take advantage of 3-D printing technology.
The Rising Popularity of