Weight-saving technology in electronic systems

Microelectronic packaging has been packing more power in less size since the invention of the integrated circuit, allowing sophisticated systems to move from floor level, to desktop, to handheld – while offering more sophisticated capabilities. Advances in polymers are allowing other, more traditional components to offer similar savings.

However, along with the benefits, launching these lighter components into production can carry unseen risks for those inexperienced in the underlying science. The pitfall is moving too quickly and too aggressively into areas outside of core competencies. Partners who already have deep expertise can reduce risk and ensure a smooth transition from concept to production.

In military and aerospace applications, the simplified definition is work = mass x distance – so reducing mass lessens the energy needed to do the work.

For an unmanned aerial vehicle, lower-weight components mean longer times aloft and greater fuel efficiency. Consider that the Global Hawk UAV contains about 850 lb of cable. Lighter weight cable, connectors, and harnessing components can play a significant role in weight reduction.

Launch costs to put a satellite in orbit can range from $5,000 to $50,000 per pound of payload. Any reduction in weight can influence costs or allow extra weight for additional scientific and engineering equipment or more maneuvering fuel to extend the life of the mission.

Evolution of technologies

Established technologies continue to evolve to meet new demands and overcome past limitations. Today’s lightweight composite materials, for example, have greater strength and durability to make them a desirable replacement for metal. Electronic enclosures demonstrate the advances being made. A high range of fillers – from traditional carbon fibers to newer microspheres and carbon nanotubes – allow flexibility in tailoring an enclosure’s properties to meet mechanical, environmental, and electrical requirements.

Traditionally, composites have reduced connector weight by around 40%. By optimizing the reinforcing material and introducing foam into polymer matrices, an additional 10% to 20% savings can be reached. The fiber material and the length of the reinforcing fibers play a role in determining the strength of the finished part. Higher strength materials can reduce wall thickness, lowering weight. Introducing foaming agents or microspheres into a polymer composite – more difficult as the reinforcing fiber volume increases – is now possible.

Wires and cables continue to get lighter. Aluminum, once overlooked due to reliability concerns with cold-creep at terminations, is gaining momentum with more compatible lugs and splices becoming available. Since aluminum has only 60% the conductivity of copper, a larger conductor is needed to achieve the same current-carrying capacity. Even accounting for this, aluminum will be about half the weight of copper.

Even more intriguing is the prospect of carbon nanotubes (CNT) wire and cable. TE Connectivity is one of the companies commercializing CNT cable technology.

Engineered polymers also contribute savings. Cross-linked insulation and jacket materials allow thinner walls and lighter weight; resistance to abrasion, solvents, chemicals, and temperature extremes; and continuous operation at temperatures of 200°C and above.

Heat-shrinkable harnessing components have also shed weight. TE recently introduced molded parts that are up to 30% lighter without sacrificing temperature or fluid-resistant performance. New designs in copper braid offer up to 50% lighter constructions than their predecessors.
 

Make or buy?

The commercial aerospace industry is starting to regulate safety of newer, nonconventional electrical systems through programs such as electrical wiring interconnection systems (EWIS).

As a connector company, TE has extensive experience in composites for military and aerospace applications and in molded parts and adhesives for backshells and harnessing. Research in these areas is developing composite formulations and manufacturing technologies to allow high-volume, cost-effective manufacture of composite enclosures. TE has also created reliable methods of selective metallization of the composites, allowing circuit traces, shielding, and even embedded antennas to be cost-effectively integrated into the enclosure.

A composite enclosure should not be designed as a straight replacement for aluminum. Rather, the enclosure should be designed for higher functionality and efficient molding and metallization. DC and RF circuits, strain sensors, mechanical retention features, electrical connectivity, and connector housings can be integrated into the design.

Developing a core competency can be expensive and risky, and it becomes increasingly difficult to achieve competency in all the technologies a company needs. Rely on suppliers instead.

The risks of developing new competencies in-house include delays due to unforeseen design and manufacturing obstacles, higher testing costs, and sometimes failure to achieve goals. An additional competency sometimes overlooked is skillful integration.

TE recently worked with an aerospace manufacturer to develop a grounding system for composite airframes. Composite airframes require new thinking about grounding and bonding to replace traditional approaches suited to metal airframes. The new thinking requires a system-level approach that embraces connectors and backshells, harnessing, raceways, and aircraft structural elements.

Solutions for future platforms do not have to be obtained in giant leaps in technological advancement. Small improvements and sustained, planned steps with new materials and technologies may be the right approach for reducing risk of time-to-market failures or performance issues associated with totally new ideas and technology.

Whether it is the design of a powerful battery for emergency power or a lightweight wearable radio for the soldier of the future, lighter, smaller, and more powerful are always going to be driving design goals. Companies that use a sustainable approach, based upon core competencies and experience in the market, can expect to reach those goals with a higher degree of success and lower risks of failure or customer dissatisfaction.

TE Connectivity
www.te.com

About the author: John Kuster is senior product manager – electrical harness components at TE Connectivity. He can be reached at jkuster@te.com.