High-Performance Polymers for Environmentally Friendly Electronic Components

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By Edson Ito, Ticona Engineering Polymers

The time is right for green electronics. With higher energy costs, growing consumer awareness of carbon consumption, new e-waste disposal laws, and plans by the Obama Administration to invest in renewable energy projects, computer and electronic gadget manufacturers are starting to leverage "green credentials" into bragging points for various products. Material suppliers are developing new materials to help manufacturers produce eco-friendly system components without hazardous chemicals such as antimony, beryllium, and phthalates.

Retailers are getting behind the push for sustainable packaging and eco-friendly products. One example involves Apple and how it promotes the eco-friendly position of the MacBook Air, with a focus on its recyclable aluminum enclosure, as well as a mercury-free LCD display with arsenic-free glass. Another is Apple's release of the new iPod, now free of both PVC and brominated flame retardants.

Like Apple, many computer and electronic gadget manufacturers are reducing their use of toxic chemicals, and committing to the elimination of all PVC plastic in cables and brominated flame retardants in system components. This was most evident at the latest Consumer Electronics Show (CES) in Las Vegas, where many major vendors devoted sections of their booths to publicize their environmental efforts, especially inside their products.

In general, however, many computer and electronic gadget manufacturers still need to remove or monitor the presence of some potentially toxic additives in the plastics they use, as illustrated by Greenpeace in its "Guide to Greener Electronics."

Many material suppliers are enhancing and developing new materials to help manufacturers produce eco-friendly system components without the use of hazardous chemicals such as antimony, beryllium, and phthalates. The broad variety of these material solutions is expected to help customers comply with hazardous substance restrictions and waste directives such as the EU's Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE) directives. These directives restrict the use of certain brominated flame retardants in electrical and electronic components, key end-use applications for engineering polyesters.

Today, some existing V-0 halogen-free engineering thermoplastics*, such as some liquid crystal polymers (LCPs) and polyphenylene sulfides (PPS), already offer inherently flame-resistant properties without the use of either halogenated or non-halogenated flame retardants. Highly crystalline, thermotropic (melt-orienting) thermoplastic LCPs have a UL V-0 rating and can withstand high SMT soldering temperatures, including those needed with lead-free solder. Eco-friendly PPS formulae can withstand high-temperature assembly as well, including some lead-free processes.

Additional features being added to RoHS-/WEEE-compliant LCP chemistries include low warpage, resulting in flatter molded parts such as CPU sockets and DIMM connectors. These components must maintain tight dimensional tolerances after lead-free reflow soldering temperatures of 260°C.

Introduced about 20 years ago, LCP has evolved to include innovative grades that keep pace with market needs for high flow for thinwall and complex shapes, higher temperature resistance, fast cycle times for high production rates, flash free, high tensile strength and modulus in flow direction, high impact strength, low coefficient of thermal expansion (CTE), and recyclability (regrind usage up to 50% with UL approval).

LCP outperforms traditional materials used in electronic applications, such as connectors, bobbins, switches, and relays. This is especially true in the case of new-generation halogen-free, high-temperature materials, which use flame retardant additives that can cause processing issues; corrosion to barrels, screws, and tooling; materials property degradation; and surface imperfections.

The other engineering thermoplastic, PPS, satisfies the UL94V-0 flammability rating without the addition of flame retardants and is ideal for use in applications where exacting electrical properties are required, such as in semiconductor components. PPS offers high end-use continuous temperature, broad chemical resistance without attack or degradation, creep resistance especially at elevated temperatures, abrasion resistance, dimensional stability with low shrink and CTE, low absorption, and excellent electrical properties.

Responding to demand for low-chlorine content and non-brominated products, new formulas of PPS fuse improved polymerization and original compound technologies to reduce chlorine concentrations to below 900 parts per million (ppm). Reduction in chlorine concentrations can be accomplished without a loss of the superior mechanical properties that make PPS resin a material of choice for making connectors, switches, and other electrical components.

ConclusionAs new laws, regulations, and requirements touch every aspect of an electronic device, from PCBs to power cords, many mobile-phone, computer, TV, and games-console manufacturers are setting timetables to eliminate hazardous chemicals in their product design. This requires component manufacturers to use alternative materials that meet the strict quality and performance requirements that customers expect without increasing costs.

Eco-friendly innovations based on new polymers are giving computer and electronic gadget manufacturers green bragging points with consumers, who recognize the growing importance of green in their purchasing decisions.

* Materials references include the Vectra LCP® and Fortron PPS®.

Edson Ito is Vectra LCP technical marketing manager for Ticona Engineering Polymers. For more information, visit www.ticona.com/halogenfree.



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