Self-aligning Coaxial PCB Connectors
Applied Engineering Products (AEP)
New Haven, CT
One of the more common problems faced by designers of RF and microwave equipment who incorporate multiple PCBs is connecting the boards directly together so that the RF signals are transmitted properly between PCBs. This problem occurs because standard coaxial connectors are rigid and soldered to the PCB in fixed locations. Thus, the tolerance buildup in mounting multiple connector pairs prevents the connectors from aligning correctly for proper mating. The traditional solution to this problem is to mount the boards separately and connect them with costly and cumbersome cable assemblies to compensate for the misalignment. This method adds size, complexity and expense to the equipment and could be avoided if the PCBs could be connected directly to each other.
A unique, patented RF connector series with slide-on mating and a floating front end that moves during the mating process has been developed to solve this problem. This agility permits the connector to be guided into proper mating alignment by the mating connector's front end, which ensures that the pairs mate properly without damage to the connectors or PCBs when suitable guide hardware is used.
Connector Description 
The SLB/SA series coaxial connectors are the same size as type M39012 SMB connectors and mount on a centerline distance as little as 0.350" for dense packaging scenarios. The connectors feature gold-plated brass bodies and contacts as well as polytetrafluoroethylene insulators, and exhibit good SWR from DC to 6 GHz. Figure 1 shows the SWR for a pair of connectors mounted on an airline.
The connectors' unique floating front end tilts and shifts during mating to accommodate axial and radial misalignment between the mating pairs. Figure 2 shows a misaligned connector pair as the connectors come into contact. The male jack connector tilts as it is guided by the closed-entry hood of the female mating plug. Finally, when fully mated, the front end of the self-aligning connector is shifted radially into alignment with the mating plug. During this process, the spring washer prevents ground interruptions and compensates for axial misalignment. The connectors feature a slide-on mating interface and low mating force of only 1.5 lb (avg) per mated pair. Figure 3 shows a group of three connectors mounted on a test PCB before and after mating.
Applications
These self-aligning connectors are mounted using industry-standard PCB drilling tolerances, thus manufacturers are not required to change any board drilling procedures or tolerances. By eliminating the need for cable assemblies, these connectors permit equipment designers to mate PCBs directly in a parallel stack, in a right-angle daughtercard configuration, or easily customize their equipment using plug-in component modules. The end result is more compact and less costly assemblies without a sacrifice in RF performance.
Applied Engineering Products (AEP),
New Haven, CT
(203) 776-2813.