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If we look, for instance, at a Lightning cable, its connector is shaped like "—", with receptacle being "=". Apparently, this construction contributes to durability, to the ease of use, and lowers production costs.

USB C, on the other hand, opted for a connector shaped like "=" and receptacle like "≡". This is more likely to break from pressure and more prone to accumulating dust. What is the reasoning behind this choice?

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    \$\begingroup\$ more than likely NIH. If they made it loop like the lightning you would either get "why not use lightning over USB-C" or equally the issues with non Poka-yoke \$\endgroup\$ – JonRB Jan 23 '16 at 20:51
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USB micro-B is known for its high mate/demate cycle specification relative to the other USB connector types. It achieves this by having the sprung contacts in the cable, rather than in the device. This way, only the cable is subject to deformation, and can be replaced if it becomes unreliable. The contacts in the device are fixed and so do not wear or deform as readily.

The type C connector is similar to the micro-B, and was presumably designed with the same principle in mind, because it is also rated for 10,000 cycles. To have sprung contacts in the cable without any sort of shroud will mean that they protrude from the body of the connector. This could result in their catching on something and bending or breaking off.

The Apple Lightning connector's durability is discussed in US9004960. I could not find any mention of how many mate/demate cycles it is rated for, apart from "sometimes thousands". This sounds like it might be less than 10,000.

Note that the mini-DisplayPort connector (used for Intel's Thunderbolt in past iterations, now to be superseded by the USB type C connector) is designed along the same lines as USB type C. It seems to be an established design principle for this sort of application.

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They likely wanted a contiguous ground shield for the high speed data (most high speed buses do have shielding for alien cross talk). Anything past that would be pure speculation.

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All sources say "Improved EMI and RFI mitigation features" but I'm sure it's the same reason every other power connector is shielded... to stop the pins shorting out on metal objects unintentionally.

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