Has anyone seen quick-connect M6 nuts, for use on PCBA ring crimps in test jigs - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: July 23, 2023, 03:56:36 am
content: Just wondering if anyone has seen something that is basically an M6 nut but intended for rapid install/remove.Something you don't need to screw-on. Maybe it's in 2 halves and you can simply clip it with internal down force spring.It would be used to allow for rapid connect/disconnect of test jig cables (with ring crimps) onto a PCB mount press fit M6 terminal.It could just be a nut, or a nut and wire terminal in one.Currently i'm using a 3D printed spacer over a normal M6 nut so the number of turns required is small.But I would like something quicker if possible.(I looked into option of a pogo-pin array under the PCB up against the press fit connector pins/pcb copper. But that has its own problems due to currents involved and requiring so many pogo's in parallel that the press down force is huge (5 terminals * 16 per terminal = 80 * 2N = 16kg) )

author: ajb
author_rank: Super Contributor
timestamp: July 23, 2023, 04:29:48 am
content: How much current are you trying to get in and out of these things? Which is the DUT, the wire harness or the PCB? Guess it's the PCB if current is a concern, since you wouldn't need a ton of current for most harness testing purposes?Conventional solution to pogo pin pressure is to use a mechanical clamp system, like a cam-like style of thing that has high mechanical advantage to make opening and closing easy. Potentially many other solutions--maybe even just some big heavy alligator clips that can clip onto the terminal?

author: Psi
author_rank: Super Contributor
timestamp: July 23, 2023, 04:57:16 am
content: Quote from: ajb on July 23, 2023, 04:29:48 amDUT is PCBA with the press fit terminals on it. To test it I have to connect the motors to the PCB with thick ring terminal wires.The power also comes in on other terminals as well. So 5 terminals total (motors have a common).It peaks up to 180A when starting and when I test the motor overload trip, but usually during test it's around/under 40A.I found some much cheaper INGUN (clone/copy) pogo's on aliexpress that i'm going to do some testing with, see how well it works.If it seems to work ok or borderline with the clone pogos i'll order some genuine ones.Just don't want to fork out $400 for 100 pogos and receptacles unless it's going to work.Was thinking of using an array of 4x4 of these 16Amp ones per press-fit PCB terminal.They would fit offset into the gaps between the 5x5 press fit PCB holes.However the force required to get that many to their recommend working stroke scares me.There is also the risk that the current will heat the springs up and they will lose their springiness.But given that the 180A is only for a short time, might be able to get away with using less of them16A pogohttps://ingun.com/en-GB/HSS-100-306-150-A-2000/HSS-100-0006?fbclid=IwAR38iOb58KjU8AwWl8MI8eeTEnOA2agJyUq0LKrHyRx1ZG6O90Q80uNYsfsThis is the kind of terminalhttps://www.digikey.co.nz/en/products/detail/w%C3%BCrth-elektronik/7461098/2092196

author: JURP
author_rank: Contributor
timestamp: July 23, 2023, 07:31:10 am
content: Quick nuts are popularly used on CNC.Look for example for:1) TWINNUT 3817722) Elesa+Ganter GN 6303.1-M63) MORTON MACHINE WORKS code 01376664You just have to survive the price.

author: Gribo
author_rank: Frequent Contributor
timestamp: July 24, 2023, 06:57:50 pm
content: If you must use pogo pins, Ingun also has 100A probes.If you can use multiple probes QA tech has 24A partshttps://www.qatech.com/en/products/conventional-probes/187-25.html

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 24, 2023, 07:11:28 pm
content: Maybe add a spacer to the lugs on the test setup the nut only needs a couple of turns?Also, using threaded spacers, maybe 10mm long, instead of nuts makes them much easier to start and hand-tighten

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 24, 2023, 07:20:54 pm
content: I also wonder if you could make something like croc/alligator clips with a cylindrical profile inside the jaws. Maybe copper braid.Or maybe cut a brass M6 nut in half and solder the halves inside the jaws of croc-clips

author: langwadt
author_rank: Super Contributor
timestamp: July 24, 2023, 07:58:46 pm
content: Quote from: Psi on July 23, 2023, 04:57:16 amif it is just for a test fixture can't you just make a "hat" that clamps on top pushing on top each of the ring terminals

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2023, 01:19:42 am
content: Quote from: langwadt on July 24, 2023, 07:58:46 pmYeah, that is the kind of thing i want. Do you know if anyone makes something like that ready to go?

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2023, 01:22:28 am
content: Quote from: mikeselectricstuff on July 24, 2023, 07:11:28 pmYep, that is my current solution, 3D printed hex block with the nut recessed into it.It's good, but still slowish because you have to do 5 of them

author: langwadt
author_rank: Super Contributor
timestamp: July 25, 2023, 01:29:16 am
content: Quote from: Psi on July 25, 2023, 01:19:42 amI was thinking something like this:https://www.robotdigg.com/product/1527/PCB-testing-jig-PCBA-test-fixturebut instead of pogo pins on the movable top plate, have tubes the size of an M6 nut pressing down on each of the ring terminalsso you put the ring terminals on and clamp them all with top plate in one go

author: ajb
author_rank: Super Contributor
timestamp: July 25, 2023, 03:19:00 pm
content: Quote from: mikeselectricstuff on July 24, 2023, 07:20:54 pmI'd be concerned about the contact pressure not being high enough for 180A with that method. Without sharp points like pogo pins have to punch through oxides and crud on the surface or a lot more contact force having more contact area doesn't necessarily help. Might be fine as long as everything stays clean.I think the best solution would be a pretty conventional bed-of-nails setup, more or less along the lines of what langwadt linked. Designing those sorts of things can be a bit tedious, though, so might not be worthwhile unless the quantities are relatively high.Quote from: Psi on July 23, 2023, 04:57:16 amMight be worth including a couple of extra pogo pins for each terminal so you can monitor contact resistance. Two additional pins that are isolated from the other pins but contact the same copper area would allow you to take a four-wire measurement of the total pin+contact resistance for your power handling pins. The measurement pins don't even need to be the fancy high-current ones. You could take measurements periodically to monitor if/how the contact resistance degrades over time, or make it part of every test cycle. The latter would be a good way to verify that the board is properly loaded into the fixture before starting the test and trying to get 180A through only half of the pogo pins. In a more pedestrian test fixture you might just use some detector pins set at a lower height than the rest of the test pins for that purpose.

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2023, 10:15:33 pm
content: Quote from: ajb on July 25, 2023, 03:19:00 pmgood idea

author: tszaboo
author_rank: Super Contributor
timestamp: July 25, 2023, 10:24:16 pm
content: Can't you test the PCB before the press fit terminals are installed? You have a nice number of through hole connections where those pogo pins would make ideal contact.

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2023, 10:40:21 pm
content: Quote from: tszaboo on July 25, 2023, 10:24:16 pmI could do, it's an option.

author: ajb
author_rank: Super Contributor
timestamp: July 26, 2023, 01:28:04 am
content: Quote from: Psi on July 25, 2023, 10:40:21 pmOn the other hand, do it after and you can throw a couple pogo pins on the legs of the terminal for a 4-wire measurement to validate the press fit.

author: tooki
author_rank: Super Contributor
timestamp: July 27, 2023, 12:23:42 am
content: What about a female “banana” jack (I use the term loosely, because these jacks have the springy lantern inside the jack, intended for use with solid pins) like the ones from Stäubli? They come in numerous diameters, including 6mm, which you could push onto the M6 stud.Look at Stäubli 01.0005:https://de.rs-online.com/web/p/bananenstecker/4321698Pages 12-13 ofhttps://www.staubli.com/content/dam/spot/PL-Main-Uninsulated-11013980-en.pdfPage 31 shows crimp adapters to turn those into wire-mounted sockets if need be.The 6mm ones are rated for 100A, and up to 180A at higher temperatures, so surely perfectly adequate.Also, there are similar 6mm sockets sold as medical grounding connectors, see pp.17-18:https://www.staubli.com/content/dam/spot/MED-Main-11014109-en.pdf

author: Psi
author_rank: Super Contributor
timestamp: July 27, 2023, 11:37:14 am
content: Quote from: tooki on July 27, 2023, 12:23:42 amThat is interesting, might be worth buying one of those to check them out.Thanks