Balun connectors for digital transmission lines just got smaller thanks in part to a liquid-crystal polymer (LCP). They are one-third smaller in diameter than conventional baluns and can be array-mounted with center distances just 11 mm apart.

The miniature balun can free up precious space for additional lines and links in telecom exchanges already carrying thousands of balanced/unbalanced links, says Steve Manche, mechanical engineer at AC&E. In addition, the dimensional stability and strength of the 30% glass-filled LCP lets the twisted-pair-side of the connector, called the stuffer cap, terminate the wires when mated to connector base. The LCP called Zenite 7130 from DuPont Engineering Polymers, Wilmington, Del., has a heat-deflection temperature of 289°C which helps ensure that the connectors pass a 112-day, 100°C test to check assembly dimensional stability. Parts made from a competitive high-temperature amorphous nylon failed similar tests.

Heliro Pty Ltd., New South Wales, Australia, molded parts used in the miniature balun connectors. Both parts have tiny intricate details required for assembly and termination, which are repeatedly reproduced during molding thanks to the flow properties of Zenite LCP.