"Test rig" for moving pogo pin connector up/down to PCB - Page 1
Forum section: electronics / general

author: Martin F
author_rank: Regular Contributor
timestamp: July 22, 2019, 08:46:17 pm
content: Hi all,We're looking for a solution for our test rig, see below image.Basically, we're connecting a PCB (our "device") to a test setup module. Once connected, we need to hold down a TagConnect connector onto the PCB and put it through a set of holes in order to transfer the firmware to the PCB. The connector needs to be held in a fixed position during this.The connector is similar to this:https://www.thedebugstore.com/images/D/Lg-Tag-Connect-TC2050-IDC.jpgCurrently we achieve this via a manual process of adding a "resistance" to the other side of the PCB as in the picture. But we'd like some form of easy "handle test rig", where we can e.g. pull a lever or similar to move the connector up from the PCB and down into the PCB holes as illustrated.The idea would be to screw our test module and the "test rig" onto e.g. a wood platform to affix everything.We've looked for very long with no luck. Any ideas for such a tool?Best,Martin

author: Nusa
author_rank: Super Contributor
timestamp: July 22, 2019, 10:17:30 pm
content: I'm not sure where the USB in the title comes in, since I don't see any USB connectors in the picture.Anyway, since you're talking through-holes, consider doing it from the bottom instead of the top, although the top will work.Search for "pogo pin test fixture" for examples of what I mean. The fixtures tend to be custom-built for the application, by necessity. Only populate the pins you actually need to use to keep it simple.

author: Martin F
author_rank: Regular Contributor
timestamp: July 23, 2019, 09:07:08 am
content: Hi again,I've updated the post - we use a Tag Connect debug conector, which looks similar to this:https://www.thedebugstore.com/images/D/Lg-Tag-Connect-TC2050-IDC.jpgIt contains 4 fixing pins and pogo pins in the middle. It could be added from below, but the issue is that we need to connect the PCB to the test setup module via two DB9 connectors. In order to do this, the Tag Connect connector would need to be "away" during the DB9 connection and then moved into position afterwards, which would provide an equivalent challenge in regards to tooling - just from below instead of from the top.Our assumption would be that a tool from the top might be easier to add to the setup and require less customization.What we're looking for is almost like a chemistry tube holder or something similar - we just need it to be possible to add a grip around the Tag Connector, make the height adjustable (easily, ideally) and be able to maintain a completely fixed position once affixed to a platform of e.g. wood.

author: Berni
author_rank: Super Contributor
timestamp: July 23, 2019, 09:23:32 am
content: If you just want a big lever to plug it in and out you can get a drill stand and clamp some wooden piece in there to hold your connector.Like this:But when it comes to programming or testing jigs i found 3d printing to be very useful to quickly make something that easily gabs onto a board while having some pogo pins mounted on another board in the jig. Hinges or sliding things are still best made with real metal rods, but various clips and latches can be 3d printed as part of the part to provide easy ways of locking down the DUT in the jig during programing.

author: Martin F
author_rank: Regular Contributor
timestamp: July 23, 2019, 09:26:44 am
content: Hi again,I think the above would be quite close - maybe if there's a smaller/lighter version of it as we'd ideally need something compact.Any suggestions where we might look for such?Martin

author: Berni
author_rank: Super Contributor
timestamp: July 23, 2019, 09:40:24 am
content: They come in all sorts of sizes. The smaller ones tend to be made for dremel tools like this:https://www.alwayshobbies.com/tools/power-tools/proxxon-micromot-mb-200-drill-stand-28600-502021

author: Gribo
author_rank: Frequent Contributor
timestamp: July 23, 2019, 10:20:29 am
content: You want to apply force evenly, and not bend the board.Check out test jig manufacturers, it might be cheaper in the long run.Personally, I have worked with Ingun and ECT. It might cost you more, but you will get a more robust solution.

author: Kjelt
author_rank: Super Contributor
timestamp: July 23, 2019, 10:31:10 am
content: Normally programming jigs can be made by any mechanical shop/company.You can even do it yourself if you have a cnc machine since all materials are available in aliexpress or locally.Usually the pcb is placed in a "mold" made of Delrin/Pom or even more preferred an esd proof but isolating material.The pogo pins can be set from below so carefully pressing the pcb into the mold and locking it with mechanical holders is one way.Another way is as you suggest lowering the socket or pogopins from above.How those normally look and differ from the suggested drilling stands is that they are much smaller but have two (dual) round guidances to lower the physical deviation by limiting the degrees of freedom (twisting).You can look at an example of one of the stands here at the first picture, it was originally such a programming jig however I use it as a spotwelder since it came into my possessionIf you want I can remove the lower part so you can have a better view of the construction.https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/msg1334962/#msg1334962

author: NorthGuy
author_rank: Super Contributor
timestamp: July 23, 2019, 01:31:54 pm
content: Instead of tag connect, you can place a number of holes distributed over the PCB (no reason to keep all the pins together, and distributed placements actually takes less space). Then you can use large pogo pins (such as E-100 series on eBay) which are easy to insert into holes and hold manually for couple seconds until the programming is done. The pin themselves can be soldered into a relatively large holder made of two small PCBs, which makes it easy to hold during programming without touching any contacts. Operator doesn't have to be precise to do this, nor does he need any special skills.If the programming is taking longer than few seconds, you can install a bracket above the PCB. Then the operator presses the pin holder onto the PCB, then moves it under the bracket. The pins have more than enough spring to latch the pin holder under the bracket.Of course, cramming nice big pogo pins into a small tag connect is not something you can easily do.

author: SilverSolder
author_rank: Super Contributor
timestamp: July 23, 2019, 01:50:26 pm
content: Quote from: NorthGuy on July 23, 2019, 01:31:54 pmNot sure I understand the holes-on-pcb idea, won't the pogo pins make unreliable contact if they are going through holes?

author: NorthGuy
author_rank: Super Contributor
timestamp: July 23, 2019, 01:57:58 pm
content: Quote from: SilverSolder on July 23, 2019, 01:50:26 pmIt depends on the size of the hole. You choose the size so that only the tip of the pogo pin comes in. If the size is correct, the contact is reliable.

author: Martin F
author_rank: Regular Contributor
timestamp: July 23, 2019, 03:18:30 pm
content: Thanks for all the great inputs!I think the tool suggestion by Berni is really close - if anyone has suggestions for similar tools it’s very welcome. I’ll give it a look as well. We need about 10-20 of these, hence why we ideally want something off the shelf and compact.The custom pogo pin solution ideas are also good, though we ideally want to keep the current connector solution as we will otherwise have to change our pcb design, which we prefer to avoid at this stage.Martin

author: Gribo
author_rank: Frequent Contributor
timestamp: July 23, 2019, 05:06:36 pm
content: You can have pogo pins with 50mil pitch, it is the same pitch as the TagConnect.

author: Nusa
author_rank: Super Contributor
timestamp: July 23, 2019, 07:53:25 pm
content: If you want any sort of automation, I'd suggest a z-axis slide designed for the cnc industry.examples:https://www.ebay.com/sch/i.html?_nkw=z+axis+slide

author: mrpackethead
author_rank: Super Contributor
timestamp: July 23, 2019, 11:33:48 pm
content: you can buy pogo pin test rigs in china for suprizing small amounts of money.

author: mrpackethead
author_rank: Super Contributor
timestamp: July 23, 2019, 11:35:51 pm
content: https://fixton.en.alibaba.com/productgrouplist-803705358/Universal_Test_fixture_jig.html?spm=a2700.icbuShop.cunta628ec.2.569e5d99anAfXj

author: langwadt
author_rank: Super Contributor
timestamp: July 23, 2019, 11:59:27 pm
content: Quote from: Martin F on July 23, 2019, 03:18:30 pmhinge the the horizontal arm to the vertical post, with a long enough hinged arm it should be closeenough to a vertical movement on the pcbor,https://www.robotdigg.com/product/1527/PCB-testing-jig-PCBA-test-fixture

author: Koen
author_rank: Frequent Contributor
timestamp: July 24, 2019, 11:37:46 am
content: I use NorthGuy's way but instead of storing big jigs, pressing by hand or adding clamps, I simply glue a weight above the testing/programming PCBs. And place the tester atop whatever PCBs I need tested. Simple, cheap, practical.

author: jc101
author_rank: Frequent Contributor
timestamp: July 25, 2019, 04:51:21 pm
content: TAG Connect do have a friction holder for the legless TAG connectors see the CLIP items herehttp://www.tag-connect.com/accessoriesI use these for debugging, so depending on how long you need to keep things connected for might be an option. You could, potentially, attache one of these under the board for more production use.

author: Martin F
author_rank: Regular Contributor
timestamp: July 25, 2019, 05:23:11 pm
content: Thanks - we use those today for debugging, but they are a bit cumbersome to add and will wear out over time.Our test will take approximately 5 min per unit and will be done in 5-10 parallel setups.The lever option to move the connector down from the top would be ideal.

author: jc101
author_rank: Frequent Contributor
timestamp: July 25, 2019, 05:26:14 pm
content: Before I found the CLIP modules I used to use a block of Blue-Tac which would work quite well. No good for debugging but might last 5 to 10 mins. Just need to squish it back into shape between tests.

author: KL27x
author_rank: Super Contributor
timestamp: July 26, 2019, 02:38:56 am
content: The way the china custom jigmakers generally do it is to make you a custom arbor press. A lever goes up/down to move the connector. And then the bed/table will generally be custom made to exactly fit the pcb. So it's good for only one PCB, and there's no adjustability of the Z axis. So you if you did want to modify it to another job, you have to work to a small tolerance in how you attach your interface, if it's even possible within the height limitation. And overall the press is cheap and heavy with crude/rough action and is basically a big piece of landfill when your original job is over.QuoteWhat Berni suggested is exactly what I use when I need to do this. Specifically, I use the Proxxon mini drill press. But it needs some modification.If you use a regular drill press, you would have to hold the arm down the entire time, and that would defeat the purpose. Even if your testing took only 5 seconds rather than 5 minutes, this would still be annoying. The trick is to reverse the spring. Slide the head off the rod and put the spring on the other side of the sliding part, so the spring presses the head downward. But you need some further handiwork in order to lift the head to take out and put in the next PCB. If you just lift up on the handle, you'll lift the entire press, and even if you affix the press to a bench, this is just awkward.So you'll want to add a second fixed handle/rod to the press head that is positioned above the regular lever, so you can squeeze the handles together to lift the head that half an inch or so. It's a tiny job for anyone handy, but this might be intimidating to the uninitiated. You can drill and tap for a machine screw (or just drill and screw in a slightly oversized wood screw) right into the side of the aluminum alloy press head, to affix this stationary handle. So what I have done to multiple presses is pretty much take a small block of wood, drill a half inch hole in it, cut the block to the appropriate angle so when you stick a 1/2" dowel in the hole and stick the block against the side of the press head, the angle of the dowel matches the angle of the press handle. Then screw it on.The mini Proxxon press has all the adjustable depth stops you need to make the amount of movement ideal without wasted motion. It comes with an adjustable fence to aid in aligning the PCB. If that is not good enough for indexing the pcb, you can just slap down some guide rails or whatnot, as needed. Hot glue or whatnot is good enough.Verify test result, squeeze, remove pcb, insert next one, let go, start test. Move to next station.The Tag Connect is annoying, because it's an HDPE bead and it doesn't affix easily to other things. I suppose a big nuff glob of hot glue +- some string will do the job to connect it the press head.This might sound like overkill, but your worker bouncing around between 15 stations will thank you and will do a lot more work over a shift for the same amount of money. This is a boring, repetitive, and thankless task, so it is probably worth it to make it as effortless and reliable as possible. Whoever is going to do this didn't spend weeks on the firmware and PCB design, and they could give a crap how clever a cheaper alternative is. They (or you, once you've done a thousand) only care how well it works. The reverse Proxxon is sex on a stick. But if this is a short term contract/need, and you don't intend to ever do this kind of thing again, perhaps hot glue and some large clothes pins?

author: Martin F
author_rank: Regular Contributor
timestamp: July 26, 2019, 10:48:50 am
content: Thanks KL27x, really appreciated the detailed answer. I'll discuss in the team if the customization would be doable as you outline. If so, it's probably an ideal solution as you outline.One alternative route I had a look at was using rail sliders. The idea would be to fit a horizontal sliding rail where the Tag connector would be affixed via a second basic grappling tool. The weight of this second tool and the rail itself would then ideally suffice to hold down the tag connect. When the PCB is done, the rail slider would be lifted up, the PCB removed and the next inserted, after which the rail slide could be let down again.I looked at something like this:https://www.alibaba.com/product-detail/LGD8-70L-100-supplier-vertical-sliding_60295880935.html?spm=a2700.galleryofferlist.normalList.55.3aa32abeNt0Z82However, I've not found an ideal match yet for this. And it may be that there are some practical reasons it won't really work.It's strange that there's no "proxxon" similar alternative out there with the functionality that you customize KL27x - one would think there'd be quite a lot of applications for this kind of tool, perhaps also in completely different application fields..Martin

author: KL27x
author_rank: Super Contributor
timestamp: July 26, 2019, 07:33:49 pm
content: Just FYI, if you have access to the tools to build a jig out of these rails, then there is a potentially better and cheaper solution.I'd suggest you rig up your own version of the ubiquitous "china jig." For the up/down action, I would try "90 degree toggle clamp." Then you just need a piece of plywood cut to size for the base/table, and a second piece at a right angle to screw the toggle clamp to. This upright piece would have a cutout to give the throat clearance for the pcb.https://www.amazon.com/POWERTEC-20323-Quick-Release-Toggle-Clamp/dp/B076H3WRLZ/ref=sr_1_41?keywords=90+degree+toggle+clamp&qid=1564169561&s=gateway&sr=8-41Actually, rather than plywood, 3/4" hardwood or MDF might be easier, so you can just glue the pieces together edge to face. To connect plywood edge to face, you probably want to cut a nicely fitted dado with a tablesaw or a router.One annoying thing with the 90 degree clamp is that tuning the stopping/clamping height of the arm is done by screwing an inner arm in/out of the upper arm, then locking it down with a lock nut. If you adjust it, you will rotate the TAG Connect you somehow attached to it. So you would have to futz with it a bit more getting it dialed in.

author: langwadt
author_rank: Super Contributor
timestamp: July 26, 2019, 07:50:09 pm
content: just make a lever

author: KL27x
author_rank: Super Contributor
timestamp: July 26, 2019, 07:58:32 pm
content: When you're rotating through 10-15 stations all piled with good boards, bad boards, untested boards, and keyboards and mouse and programmer, you want a small footprint that doesn't skip and require restart if the jig gets bumped. (Or worse, give you a false "BAD" when you're not looking.) Maybe Fred walks by and bumps the bench, making all the tests go bad.That might work perfect. It might work pretty good. Pretty good might be pretty bad when your test takes 5 minutes.If you are designer/programmer, only, you can see the end of the job. You can say, if I do it like this, I'll save X dollars. You might need to do some support/maintenance down the road, but for the most part you wash your hands of the project and forget about it. But for the people who produce and sell this product, this job doesn't end. As long as they make/sell this product, this job goes on indefinitely. So saving a few bucks upfront can be counterproductive.

author: KL27x
author_rank: Super Contributor
timestamp: July 26, 2019, 09:52:33 pm
content: Sorry, I said 1/2" dowel, before. I just checked and I use a 3/8" dowel. 1/2" would be huge.Here's a pic if that helpsRegular unmodified press headModified presshead.Also, I noticed the press head is entirely hollow in this whole area, and the bottom is completely open. So you could use nuts to secure machine screws, if you managed to screw up your holes/threads.This one has #4 machine screws tapped right into the head, but when I did this the first couple times I didn't have taps and just screwed wood screws into the holes. Those still work fine.Notice when you drill the hole for the dowel, it should go into the endgrain. Then cut the block at an angle. If this looks too "how ya doin," you could just as easily use a block of HDPE and stick a brass or aluminum tube into it. Drilling into HDPE will leave a tight hole that makes a good interference fit to the same dimension rod/round/tube without any need for adhesive or cross pins in this particular application.As you might imagine, this squeeze lever gives fantastic control while lowering the head, which is handy for getting the TAG Connect's guide pins into their holes. I actually do have experience with TAG Connect in the past.I hope to never see it again, but I still have a modified TAG Connect. The pins assembly can be liberated from the stupid bead. I don't remember how I did this, but I imagine it involved a saw and/or a knife.The guide pins are shortened. (So they don't have to stick out thru the other side of a PCB, Tag Connect people!?)This one has the pins angled, for handheld ergos.

author: Martin F
author_rank: Regular Contributor
timestamp: July 27, 2019, 10:28:28 am
content: Thanks again for all the awesome inputs - a lot of cool inspiration as well. Appreciate it

author: KL27x
author_rank: Super Contributor
timestamp: July 27, 2019, 08:49:14 pm
content: Great. Once in a blue moon I still have something useful to share.To the regulars, I'm a know-it-all text wall on a record number of ignore lists.