Novel High-heat Polyester Lets Tyco Keep Its PBT ToolingNovel High-heat Polyester Lets Tyco Keep Its PBT Tooling

A new grade of thermoplastic polyester enabled Tyco Electronics to use existing molds when a customer upgraded the thermal specification of an automotive connector (photo). Tyco was making the parts in polybutylene terephthalate (pbt), but the customer decided on higher soldering temperatures for the memory module that the connector was used on. pbt did not meet the specification, and Tyco considered a high-temperature nylon.

This would have meant retooling, owing to differences in material shrinkage. But Eastman Chemical proposed Thermx CGT33, a glass-filled poly(cyclohexylene-dimethylene) terephthalate (pct). It has the necessary thermal properties (melting point of 290°C compared to 225°C for pbt), but the same shrinkage as the initial glass-filled pbt. In addition, Tyco can use the same color masterbatch.

pct also has higher dimensional stability than nylon, since it does not absorb water. And, it is less expensive. Eastman Chemical Co., P.O. Box 431, Kingsport TN 37662 www.eastman.com