Different styles of USB Type-C connectors - why?

[HwAoRrDk]

While looking at USB Type-C connectors, I've noticed that some manufacturers make two different styles of connector: one with spring-type fingers in the outer shell, and one without. The latter is overwhelmingly the most common.



Question is, what is the difference and why would I want to use one type over the other?

I combed through the USB Type-C Cable and Connector Specification and the only reference I could find was the following section, where they refer to them as "external EMC springs".

3.2.2.4 Optional External Receptacle EMC Springs (Informative)
Some applications may use receptacles with EMC springs that contact the outside of the plug shell. Figure 3-20 shows a reference receptacle design with external EMC springs. The EMC spring contact landing zones for the fully mated condition are normative and defined in Section 3.2.1.

So, does that mean that the other kind of connector has internal EMC springs? Or is the external type having additional EMC springs? The spec doesn't elaborate why you might use one or the other either.

[amyk]

Just taking an educated guess, but the "totally enclosed" type might offer better protection against dust ingress, but be slightly thicker and/or have weaker springs as a result, while the "open frame" type allows weakend springs to be repaired with gentle pressure, at the expense of allowing more dust ingress.

[HwAoRrDk]

Just taking an educated guess, but the "totally enclosed" type might offer better protection against dust ingress, but be slightly thicker and/or have weaker springs as a result, while the "open frame" type allows weakend springs to be repaired with gentle pressure, at the expense of allowing more dust ingress.

Regarding dust ingress, that kind of makes sense, but then again most of the time these connectors are inside an enclosure, so dust ingress isn't so much of a factor, surely?

I did think maybe that the one with external springs is perhaps rated for more insertion cycles, or more secure insertion, but according to the datasheets of the two examples I previously posted (internal and external) they are both rated for 3000 cycles, and the insertion/removal force is the same. The only difference I see is that the internal one is rated for 5A vs. 3A for the external.

Maybe the external kind has lower shield contact resistance, or more reliable shield contact, for better EMC performance?