Comment by mastax
2 years ago
> Why does this cable have all 24 pins when only half of them are connected? The extra pins could help the plug sit more securely in its socket. Another guess: the same factory makes Thunderbolt cables, and it’s cheaper to maintain just one design, even though that means wasted material and effort.
The highest volume manufacturers may be fully integrated. Usually how it works, especially for these relatively low volume no-name brands, is they buy connectors from one vendor, PCBs from another, cables from another, plastic moldings from another, and then assemble them together (which may also be subcontracted). The assembly process doesn't have to be sophisticated: a small warehouse with a few workers with soldering irons and some jigs. Even some medium-volume assemblies like the USB-C front panel cables for major computer case brands are soldered by hand by a handful of workers in a small building.
Almost all of the USB-C connectors which are available off the shelf have all of their pins populated. Pins are very cheap. You need to be moving a whole lot of volume before it makes sense to go to your connector manufacturer and ask for a custom one with missing pins.
are they really hand-soldered? They look so small! Isn't there a machine that is cheaper for high volume soldering of those small connections?
Soldering small stuff can sometimes be easier, because at that level surface tension will do the job for you. So hand soldering 14 pins on a small size TSSOP package can be faster than soldering a SOIC (through hole) package (google drag soldering — just be careful with that in certain parts of the US \s)
The hardest part with cables is to prepare the strands and keep them in place. For this you can build fixtures.
There's a pretty decent chance it is a mix of both.
USB-C connectors with pre-attached PCBs ("paddle cards") are widely available[0], and are created by a machine. Aligning the cables with the paddle card is quite tricky to automate, so humans are still used for that.
[0]: https://www.lcsc.com/product-detail/C62322.html
> are they really hand-soldered?
Probably not, at least not in the way most people think of hand-soldered. There are hybrids where a human drives the soldering iron electronically rather than holding it in their hands, although even this the rate of defects would be so high it would make it impractical at even a small scale.
Typically you have a stencil that you squeeze the solder paste through and then you put the IC on top with a tweezer and bake the whole thing with something like a hair drier. It's not that difficult to get good results without using an expensive pick&place robot.