PCB Edge USB C Connector Library
99 points - today at 2:31 AM
Sourcepeteforde
today at 3:33 AM
In a similar vein, I discovered and have started using the Tag-Connect TC2030-USB to program/troubleshoot my boards. While it's technically/originally intended as a way to do JTAG debugging, I am completely enamored with the ability to drop a footprint on my PCB and be able to connect to it without having to place a relatively expensive connector (or a connector at all) that I don't necessarily want users interacting with.
https://www.tag-connect.com/solutions-target-devices/usb-ser...
They have FTDI versions as well, for those who want the full USB boot/reset treatment.
Also, they have another connector for attaching to castellated edges. I think it's just so clever.
exmadscientist
today at 5:39 AM
They're fine for one guy using them on the bench but they are a nightmare for mass production. The 50-mil pitch is annoying to make work with a bed-of-nails fixture, the clips are fundamentally incompatible with production lines, either robot or human, the parts are expensive, and the cycle life is not there.
I have had one too many arguments with firmware people who think these things are sufficient for production that I am just done with them by now. There are other ways to do it.
ACCount37
today at 12:25 PM
This reads like a skill issue to me.
The only actual issue I had with Tag is that it takes up more space than an array of aggressively placed test points would. Which is still acceptable in some designs.
If you can't hit a massive, enormous 1.27mm pitch connector complete with dedicated indexing holes with your jig, I can't fathom how that would be the fault of the connector.
Out of curiosity what are the other ways?
BertoldVdb
today at 8:41 AM
Just put normal test pads next to the tag connect, a bit more spaced out. A bed of nails in the production line connects to that, the tag connect can be used for bench development.
I've been doing a cheap DIY version of Tag-Connect for some STM32 projects (6-pin debug). I just put the holes for a pin header near the edge of the board, and use a pogo clip to connect [0]. (These are readily available on AliExpress in various sizes.)
[0] https://www.adafruit.com/product/5433
I do exactly the same on my boards and use that same clip.
Brian_K_White
today at 3:52 AM
I just use ordinary straight pin headers and stagered via holes. The board just has vias and the cable just has a plain pin header not even pogo pins.
Same, enamored and I’m not even the EE. Elegant, no cost on the product side, and I don’t have to take the board out of the case to access it.
Doesn't it require ENIG? I wanted edge connector for my pcb project but it adds $20 to the price of pcb, that's just too much. Anyone knows card edge alternative? I'm thinking pin header but that's not very user friendly. Edge card can be inserted blindly even if you don't see the connector, pin header would probably just bend irl.
What PCB thickness is optimal? The USB-C tongue on a shieldless part I use is ~0.7mm, which is a pretty thin PCB.
They say "use 0.6 mmm"
https://x.com/AnasYMalas/status/1982060711670067350
I've found 0.8mm to make much more reliable connections, since the specification says that the tongue should be 0.7mm. 0.6mm will disconnect if the cable is angled in any way.
peteforde
today at 3:28 AM
That is a very thin PCB. For anyone reading this, 1.6mm is standard.
+copper+ENIG is going to make that 0.7mm
webdevver
today at 3:10 AM
i wonder how often you can plug/replug the connector in this case. how will the pcb material hold up? with my press-fit or clip-fit (is that a term?) 3d prints, ive noticed that 20 cycles can be sufficient to induce substantial 'loosening'.
It’s likely in the order of 10-30, especially with something like ENIG as a finish. If you wanted more cycles, you’d want to switch to a hard gold finish which would likely increase the cost substantially.
This is truly only for a debug port, not anything else.
ggm-at-algebras
today at 3:46 AM
Plug an OTG cable in and connect to that, so you don't repeat plug-unplug?
eternityforest
today at 4:43 AM
What about the force transferred by the connector wiggling? I think You'd need a very good mechanical design on the case to make it all work.
kgasser88
today at 5:41 AM
I don't think it's intended for thousands of mating cycles. It's a "free" standard programming/debugging/recovery/configuration interface.
JKCalhoun
today at 3:48 AM
That's cool but I am not sure how a customer of mine would feel if I shipped a board to them like that. (I could see trying it on a project for myself, though.)
mananaysiempre
today at 5:34 AM
The problem with USB-C connectors for hobby projects is that they are ass to solder by hand—I’m still looking for one that would use a larger pitch by shorting the four USB pin pairs for either orientation. If you’re shipping something to a customer, I think it’s fair to assume that you don’t really have that problem :)
LiamPowell
today at 8:56 AM
They're also ass to make PCBs for. The second you need 2oz or higher you start to really push the limits of what most prototype shops can do.
This is a pretty standard 2.0 receptacle, you've only got 0.2mm between pads if you follow their footprint (literally the limit for soldermask bridges on 2oz at JLCPCB): https://gct.co/download?type=PDFDrawing&name=USB4105.pdf
Get a hot air gun: it'll make your life way easier. You can tin the pads with a soldering iron, put the connector on and squirt some flux on the leads, and then just blow hot air until it reflows into place.
The_SamminAter
today at 8:14 AM
What do you do if the structural through-holes already have solder in them, that wick doesn’t seem to get? I’ve been trying to put a new USB C port onto my switch for quite a while now. (Now that I think about it, I can probably just shorten the prongs on the port and add solder after for structural strength).
ahartmetz
today at 8:57 AM
A desoldering pump (manual model, $10 or so for a decent one) is very suitable for removing solder from through-holes, if that is the main issue.
Hackbraten
today at 8:11 AM
How would tinning those tiny pads not create a massive bridge between them? Does the bridge somehow go away in the reflow phase? (Not familiar with reflow at all)
etrautmann
today at 8:18 AM
Yes, the surface tension of melted solder pulls the solder to just the pad areas (assuming you don’t have far too much)
The_SamminAter
today at 8:16 AM
Using with a little flux while tinning usually prevents the pads from bridging
To add to the sister comments, you can quite easily remove such bridges by adding flux and then touching each individual pad with a fine tipped soldering iron. It sometimes takes a few tries, but eventually the solder that’s touching the solder mask will either be wicked onto the iron or move onto one of the neighboring pads. (The trick is to touch just the pads with the iron, and not to try to attack the solder bridge itself.)
exmadscientist
today at 5:47 AM
Do you find the 6-pin charge-only Type-C connectors too small? Or the 16-pin 2.0-only ones? They seem reasonably hand-solder-friendly but I admit I've been fortunate enough to have the factory handling them for me.
mananaysiempre
today at 5:58 AM
Yeah, I find the 16-pin ones a little beyond my skill. They also feel silly—why can’t I have one with just six pins for D±, VBUS, GND, and CC1/2? I guess I could have a factory make a bunch of modules like that for me, but it definitely feels like a thing that should already exist.
(There are passive A-to-C adapters, so I see no reason why I couldn’t short pin pairs like that.)
Very clever packaging of a connector