Page 14 - 2021 High-Reliability, Harsh Environment Connectivity eBook

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5. Will the bend be maintained constantly, or will the cabling have to cope with dynamic bending over the course of its operational lifespan?
If the cabling is expected to go through many bend cycles, the durability of an FPC is likely to distinguish itself from other forms of cabling, as the materials in discrete wire cabling tend to become more brittle when subjected to repeated bending motions.
6. Where exactly will be cabling be situated in respect to the system?
FPCs have thinner external protection, which leaves their circuits very exposed. Ideally, they should be used within enclosures to ensure continued operation. In contrast, discrete wire assemblies tend to have a thicker polymer coating around their wires, which effectively safeguards them from potential damage. As such, discrete wires should be used in cable assemblies located on equipment exteriors and in other areas exposed to potential risk factors. It is also easier to secure discrete cable bundles with cable management accessories. This helps prevent unwanted vibrations, as well as wear from proximity to other components and bodywork, and it also facilitates the placement of additional protection around cable bundles.
7. Which materials should be specified?
Connectors, cables, FPCs, and accessories are available in a variety of materials. By establishing your temperature requirements early on and confirming that all of the constituent materials in the chosen cable or FPC connection will withstand them, you can avoid issues down the line. The effects of electromagnetic or radio frequency interference should also be taken into account when deciding on materials. By working directly with your cable supplier, you can verify that your cable selection is suitable for all the factors involved in your application. If your environment is too aggressive, additional protection methods may be needed. For instance, external braiding on cable bundles helps combat electromagnetic interference, but flex connections might prove a better choice, as they are inherently less prone to electromagnetic emissions. Testing may be necessary to confirm the best options for a given application.
8. What other factors should be considered?
When dealing with satellite hardware, it is essential to pay attention to the outgassing properties of the assembly. In the vacuum of space, many materials release substances that could condense on the electronic circuitry and affect its operation. Additionally, if the potential for contamination by oils, fuels, or other chemicals exists, or even the prospect of fungal growth, then precautionary measures will need to be taken.
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» A discrete wire cable assembly from Harwin’s Datamate range.