Design News for Mechanical and Design Engineers

One of the key technologies is a new plastics/metal hybrid material that eliminates soldering for electronics and also creates shielded housings. “Conductor paths and contact points for connectors and cables can be injection molded simultaneously,” says Thilo Stier, innovation manager at A. Schulman, a plastics compounder headquartered in Akron, OH.

Traditional lead frame techniques are replaced by the hybrids, called TinCo. They consist of 15 percent thermoplastics such as nylon, 30 percent of a low-melting alloy such as tin and 55 percent copper fiber. Nylon is overmolded with the low melting metal in a two-barrel injection molding machine using conventional tooling.

The material is being jointly developed by Siemens and A. Schulman. Five other OEMs are also beta testing the technology under secrecy agreements. The process was demonstrated at K 2007 in Düsseldorf, Germany, in October, on an Arburg press. Due to the high loading of copper, the hybrid has excellent specific electrical conductivity — greater than 106 S/m. Most plastic and elastomers can be used as the matrix in the compound. Cycle times are short due to the material's high thermal conductivity.

Dr.-Ing Dietmar Drummer, head of technology management at Oechsler, says, “This system is intended to show what we are already able to bring together in an injection molding process in a way that makes sense in both machine and mold, in terms of production, insertion, function integration and assembly processes.” The power source on the demonstration project at K 2007 was a conventional 9V block battery.

In the demonstration project, a three-component 67-ton Allrounder press molded lenses made of transparent polyamide with light strips made from ABS. The printed conductors are molded from the Schulman TinCo material. The three LEDs are then inserted. The upper housings with labeled lower housing sand battery are then assembled.

Conductive plastic is injected into the mold using hot runner technology supplied by Günther. To achieve all this, the mold technology combines a complete hot runner with a hot-runner/cold-runner three-platen system in a three-station rotary mold, which rotates electrically 120 degrees to the next station. The sprues are also separated and ejected using three-platen technology. Kiki and Rohwedder worked on the automation. Osram Opto Semiconductors provided the LEDs.

	This LED light strip is produced using unique materials.