ANAHEIM, CALIF. — Makers of communication and electronic devices are pushing suppliers and molders toward shielding materials with better recycling and heat-dissipation characteristics.
Some processors mold metal-coated materials into enclosures, and others electroplate housing interiors to shield electronics that control pagers, mobile telephones, computer circuit boards and automotive ABS brakes from electromagnetic interference.
But today's lighter-thinner-smaller products and higher frequencies pose challenges for these shielding methods.
Over the past three years, Structuplas NV of Izegem, Belgium, has developed production techniques for injection molding thin-wall parts for the computer industry using flame-retardant, long-carbon-fiber-reinforced thermoplastics.
Previously, Structuplas compression molded the parts with sheet molding compound and reinforced carbon fiber, John Vandaele, engineering manager, said in a technical paper to the Society for the Advancement of Material and Process Engineering symposium, held May 31-June 4 in Anaheim.
Thin parts can need more gating points, sturdier tools and injection presses with higher clamping forces, Vandaele said.
``With the help of [computer-assisted engineering and] simulation software, it is possible to estimate the high demands,'' he said.
Structuplas, a member of the Verco Group, employs 250 and operates 15 presses in Izegem and has 450 employees and 10 presses in Guadalajara, Mexico. A start-up facility in Scotland will have capabilities for assembly by June 30 and molding in January.
Inco Ltd.'s specialty powder products division is ``getting inquiries all the time about trying to combine our materials into injection molded parts,'' Malcolm Rosenow said at SAMPE.
``All the major compounders have programs ... because customers are asking for it.''
Rosenow is the division's business manager of fiber products in Wyckoff, N.J.
Inco's advanced long-fiber nickel concentrate is available in various resins for EMI shielding. Using the same thermoplastic resin as the injection molded part enhances the physical and electrical properties of the final product, Rosenow said.
He identified maintenance of fiber length as the key ``to maximize EMI shielding attenuation or electrical properties'' and recommended dry blending rather than compounding to maintain the nickel-coated carbon-fiber aspect ratio. Inco production occurs at its Clydach facility near Swansea, Wales.
On the environmental front, original equipment manufacturers such as IBM and Hewlett-Packard are driving the materials industry toward more easily recycled materials and away from electroplated enclosures, Rosenow said.
GE Plastics encourages ``proactively designing for shielding'' to control costs, Leslie Goff, custom engineering products manager in Selkirk, N.Y., said at SAMPE.
The traditional pattern has left shielding toward the end of product development behind design, electronics, packaging and manufacturing phases.
``At this point, the shielding method and cost of shielding are both dependent upon earlier decisions and can add unnecessary cost,'' a GE Plastics paper said.
Future developments will increase the demands for conductive plastics to shield devices from electrostatic dissipation and EMI. Cost-vs.-performance requirements and design flexibility along with quality and environmental concerns will drive the market toward a need for higher conductive performance from plastics, Goff said.