Feature: Connectors
Figure 1: Floating connectors can accommodate misalignment during automated manufacture
Mitigating mis-alignment with floating connectors To address these challenges, an innovative type of board- to-board connector has been developed. So-called ‘floating’ connectors derive a degree of ‘elasticity’ from a combination of a housing that can move laterally and longitudinally, and a novel contact design featuring a spring-like mechanism. In this type of connector, the housing is suspended by the contacts, which are usually housed in the male half of the connector; see Figures 1-2. Te degree of two-directional movement afforded by this
arrangement generally exceeds the potential misalignment due to the manufacturing process. Tis allows pick-and- place processes to be deployed for boards with multiple connectors in cases where the sum of misalignments might otherwise present challenges for high-speed, high-precision mating. As a result, designers can focus on design rather than manufacturing requirements, leaving them free to use multiple floating board-to-board connectors per board pair. Tis means that decisions about type and quantity of connectors can be based purely on the circuit needs rather than that of the connectors. Te spring-based ‘suspension’ inherent in floating
connectors will also contribute to connection integrity during operation, not least in applications that encounter some levels of vibration or shock – whether it be a portable device, a moving vehicle, or a factory automation system. For example, floating connectors can mitigate the performance degradation or failure from ‘fretting’, when long-term vibration causes the
Figure 2: Innovative contact design provides benefits in floating connectors
plating to wear from rigid mating pins, exposing the underlying alloy to potential oxidation.
Connector selection Whilst floating connectors can be used universally, many situations still require normal board-to-board connectors. In assessing which technology is more appropriate for a particular application, designers should consider the following: • Would the design benefit from multiple connectors per board-pair? • What is the mechanical accuracy of the automated manufacturing process?
• How much will the final product be exposed to shock and vibration during normal use?
• How oſten will the boards be separated and replaced during the product lifetime? Te answers to these questions should guide designer’s choice of
which path to take. Te connector selection process should also consider the
environmental aspects, especially the operating temperatures that the connector may be exposed to. Tis is particularly important for enclosed designs that protect sensitive electronics and where temperature changes can contribute to stress on connectors, especially if the materials differ or there are differences in board thickness. Finally, it should be noted that almost all applications will require
that the connector is made from materials that are fully RoHS- compatible and free of REACH SVHCs lead, brominated flame retardants, red phosphor (PFOS/PFOA) or antimony.
Figure 3: Retention tabs and through- board pins enhance the mechanical rigidity of floating connectors
30 May 2024
www.electronicsworld.co.uk
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