Enlighten Me On Low-ish Volume PCB Product Flash/Test Ideas - Page 1
Forum section: electronics / general

author: meshtron
author_rank: Regular Contributor
timestamp: March 10, 2025, 08:26:03 pm
content: CONTEXT:Roughly 2 years ago I joined this forum when I decided I wanted to try my hand at designing an electronic product I had been thinking about for years. With zero experience, lots of sunk hours and many mis-starts, I'm now getting close to going into production on that same product. The 5th iteration of prototype boards should get here next week and I've got 20 product testers lined up and ready to go - really exciting!My goal - and it's a lofty one - is to be in a position to be selling something like 100 boards per week by the end of 2025. I might not get close, I might go way over - hard to guess but my market is large, my price is competitive and so far everyone I've approached in my target market has expressed interest.I have a QIHE 802B PnP machine that works okay-ish for assembly and a T962 reflow oven that - while small and finicky - has proven at least consistent now that I've built my own reflow profiles. I think probably anything more than about 30 boards a week (I have a demanding day job and another technical side project) my desktop hobby stuff will be insufficient, so I'll probably engage PCBWay (who makes my boards) to do assembly for me.I built a small "bed of nails" jig for my 4th-gen prototypes and it's worked decently well. It hooks up to a 12VDC power supply (my product is for the automotive/powersports space) and is hooked to a test load for output. So, I clip the board in, flash the firmware and can test it immediately. I built that using spring pogo-pins but it seems like I'm already noticing some inconsistency in using it after only doing something like 20 boards. If I press down on it now, it will momentarily lose contact and bumping it while flashing firmware makes that fail.QUESTION:If I plan on a quantity of say 500 boards a month (keeping in mind this is a side gig), what would your approach be for flashing firmware and testing each board? I could build a nicer bed of nails setup but it seems like the contact points are (or might be) the issue. I am planning on putting pads/holes on the next board for the JTAG type pins that will work for flashing firmware, but I think 100% functional testing is the only way for me to be 100% confident (and sell as a premium product).I'd love to use something like an RPi to be able to automate that process too where I'm just clipping a board into a fixture (maybe with a clamp instead of counting on pogo pins), then hit a button and it flashes firmware, runs some tests and gives me a green light or a red light (and a printable receipt showing that info). I felt good about all that until I noticed my current pogos starting to give up.PCBWay will (I believe) test the assembled boards for me, but not sure how that works, what it costs and what happens if they assemble a board and it then fails.As with many other steps in this process, I can muddle through this as-is but would love to hear from those of you who've already gone through this phase of growth. Long term (hopefully in the next 2 years) I will have a shop with my own assembly line and some folks to help out. Yes, I know all the reasons not to do that but yes, I'm going to do it anyway for my own reasons. So I'm partially trying to solve this immediate problem but also trying to learn processes and steps that will help me be an efficient, small operation in the future.

author: thm_w
author_rank: Super Contributor
timestamp: March 10, 2025, 09:06:51 pm
content: https://www.pcbway.com/pcb_prototype/PCB_Assembly_Functional_Testing.htmlhttps://www.youtube.com/watch?v=fEvMme3ooRAhttps://www.youtube.com/watch?v=BsUbPuzelnEhttps://tinylabs.io/openfixture/etc, lots of videos online

author: jmelson
author_rank: Super Contributor
timestamp: March 12, 2025, 04:10:04 pm
content: Quote from: meshtron on March 10, 2025, 08:26:03 pmI have a fixture with pogo pins, and I started having intermittent contact. The issue was soldering flux on the connector tails getting on the pogo pins. The fix was to use water washable flux on those connectors which were hand-soldered. Then, wash the connectors in running water to remove the flux residue from the board. That fixed the issue.Jon

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: March 13, 2025, 01:34:27 am
content: Quote from: jmelson on March 12, 2025, 04:10:04 pmYeah, I'd look at that. I have fixtures with hundreds of inserts w/o problems. I always run cleaned boards.

author: Smokey
author_rank: Super Contributor
timestamp: March 13, 2025, 05:33:50 am
content: Whenever possible build programming and test interfaces into the products. I'm a fan of card edge connectors that can just be inserted into a production fixture instead of bed of nails. Cost nothing on the board except some routing space.For assembly, if you are going to be doing anywhere near 500 a month you absolutely will go crazy doing that yourself. Here is the trick. Even if you start assembling boards yourself make sure you pay yourself a competitive rate for that time and price it into your cost of goods sold. That way when you get tired of that miserable job you will have the budget to outsource it to a cm and won't start taking a profit hit.The last thing you want to do is price yourself into being forced to keep doing assembly forever because you didn't add your time to the product cost. You will become a slave to your own company with no way out.

author: ftg
author_rank: Frequent Contributor
timestamp: March 13, 2025, 08:56:49 am
content: If you want something open, but quite full featured, then Exclave from Bunnie & Co. might be suitable?Or at least a starting point.https://www.bunniestudios.com/blog/2018/exclave-hardware-testing-in-mass-production-made-easier/

author: meshtron
author_rank: Regular Contributor
timestamp: March 13, 2025, 07:41:34 pm
content: Quote from: Smokey on March 13, 2025, 05:33:50 amThanks for that - exactly the kind of stuff I was hoping to hear. I'm down the rabbit hole on this stuff now (my boards failed final QC at PCBWay so it'll be another couple weeks before I can do anything with them). I saw an old video of Dave's actually where he showed the card-edge connector with traces off the corners of the board and that makes so much sense to me! This product is a perfect fit for it too - I have 4 I/O wires and can run 4 small traces through the panel to a card edge and test almost everything.I don't know if I could get away with "sharing" programming header lines (to all 6 boards on a panel), but if I could get those to the card edge I could plug in a panel, disaster-check it (no shorts), power it on if it passes, flash it and functional test it all before depanelizing. Then that gets me thinking about updating my firmware to recognize first-boot and go through a testing routine to check everything. All seems very doable even though admittedly a fair bit of work.And duly noted on accounting for my time. We're in very good shape margin-wise and even if I outsourced 100% of assembly (including housings, packaging, etc.) we'd still be okay-ish on gross margin. Not where I'd like to be, but certainly enough to keep cash flow well and truly positive and get us across the valley between here and having our own operation. The likelihood is if we get even over 200/month I'll probably consider outsourcing 100% of the PCB part and just do the final assembly (something like 2 minutes per unit) and packaging here.

author: meshtron
author_rank: Regular Contributor
timestamp: March 13, 2025, 07:42:14 pm
content: Quote from: ftg on March 13, 2025, 08:56:49 amGreat info and first I've seen of it - thank you! Looks like a lot of good "food for thought" whether or not I buy a product from them.

author: Smokey
author_rank: Super Contributor
timestamp: March 13, 2025, 08:15:54 pm
content: Quote from: meshtron on March 13, 2025, 07:41:34 pmWelcome to volume production, which is a whole separate long term engineering project in and of itself.If your volume gets too high or you intend to sell overseas, expect to get popped for not having FCC/CE certs eventually if that isn't something you already have plans for.Quote from: meshtron on March 13, 2025, 07:41:34 pmProfit margin only gets worst, it doesn't get better. Component prices only go up over time. Shipping costs go up. Tarrifs get imposed. etc. You need to start with enough profit to take the hit later (or raise your prices, which isn't always possible)....it sounds attractive to have your own assembly line at first until you actually have to do that work week after week.Machines and facilities are expensive to both buy and run and maintain. Machines break and need repair bringing down your line and costing you money. If you don't run the machines yourself (for god sakes don't run the machines yourself) your employees are either standing around during slow times costing you money, or they leave and you need to start over training other people again costing you money.I've said this elsewhere, but if you actually get to the point of running your own PCB assembly line that has minimal failures (at real CM Levels) then you should just run a PCB assembly business since that's a profitable non-trivial skill that is learned over a long time period (through expensive machine acquisitions and expensive failures and learning).If you want to be an engineering company, then design products and have professionals build them. If you want to do PCB assembly, then just start a CM company.If your boards are failing at JLCPCB then expect like a 10x higher failure rate if you do it yourself on cheap Chinese toy machines or ancient used lines... You should probably have a talk with them and find exactly what was giving them trouble and fix that in a rev.

author: meshtron
author_rank: Regular Contributor
timestamp: March 13, 2025, 10:14:41 pm
content: Appreciate the thoughts. Yes, we've already budgeted testing for FCC 15B and CE 2014/30/EU (which the testing firm believes are what apply to our product).My boards failed final QC (for bare boards, not assembled) at PCBWay: they said it was nothing to do with my designs it was a failure in their process. Not sure I'll ever know more detail but that's that.I've been involved in manufacturing semi-complex things with complex equipment for my entire career at scales from my first entrepreneurial venture to Fortune 500. And while I don't disagree with any of your points, everything I know right now says to accomplish what I want to do, we need our own line. There's no real path from here to doing this full-time that doesn't go through having someone else do assembly for us for some period of time, so it's possible that changes my mind too.To the question at hand - yeah it does seem like 100% testing is indeed a big lift in and of itself. But between panelizing with card edge connectors and maybe some limited bed-of-nails stuff, I'm starting to see a path to make it workable. There will be a period of a few months where my testers are using the product and I can focus on designing the equipment and boards needed to make testability happen, so that's what I'll do. Lots more things to uncover along the way.

author: Smokey
author_rank: Super Contributor
timestamp: March 13, 2025, 10:41:27 pm
content: Quote from: meshtron on March 13, 2025, 10:14:41 pmCool. A lot of people that ask these types of questions are starting from the standpoint of "I almost got an Arduino example running and I think I'm ready to make 10,000 boards now so I need a pick and place. Please recommend a machine under $300." It sounds like you are in a much better placeHopefully I can learn something then. What about running a volume PCB assembly line looks attractive to you given your experience?

author: meshtron
author_rank: Regular Contributor
timestamp: March 14, 2025, 12:08:07 am
content: Quote from: Smokey on March 13, 2025, 10:41:27 pmActually laughed out loud!Not a million miles off from where I was a couple years ago. Now I know I can make some things, but the next stage is can I make 100 or 500 or 1000 things and not lose a wink of sleep worrying they might not work right.Quote from: SmokeyIn one (large) clean, comfortable (albeit a little noisy) building, with normal concrete floors, I can do 100% of the process to go from bare boards to finished, tested parts loaded into boxes to take to UPS. As compared to the manufacturing I have most experience in (CNC machining and steel/aluminum fabrication), the capital expense for equipment and the ongoing cost to run (in people, maintenance, and consumables) versus the profit the machines can produce is a relative bargain. Because most of the products we'd be producing are our own, I can make smart design decisions about component reuse that mean we can eliminate (to start) and minimize (going forward) changeover time and complexity. I've got a fair amount of experience in the automation space, and the fact this process can (at least in theory) be almost fully automated from board loader to board stacker is attractive too.

author: phil from seattle
author_rank: Super Contributor
timestamp: March 15, 2025, 05:49:39 am
content: I am currently building a test jig for my latest product. Lots of good advice so far and Bunny's blog is very helpful. The one thing I would add is try to make everything reusable/adaptable to future products. This is my 3rd time and I find myself reinventing things because the previous version just didn't fit right with the new one. Take more time to do a good design on your jig/test sw/process. I cut too many corners in the past. For example, I've built one big monolith test boards in the past. This time round I have split it into a test controller and Test Jig Base. The controller contains the smarts and is reusable. The test jig base is dumb, just a bunch of contact points. I would like to build a test tool kit but maybe that is still a bit too much effort.

author: Smokey
author_rank: Super Contributor
timestamp: March 15, 2025, 06:20:54 am
content: Quote from: phil from seattle on March 15, 2025, 05:49:39 amI know of a place that had a lot of product variants and built themselves a custom "universal tester" mainframe thing early on. That thing was a nightmare, and when the guys that built it left no one was around to modify it for new products or fix it when it broke.The conservative approach is to use as many off the shelf components as possible and only create custom anything when absolutely necessary. This will probably be more expensive per test station to add more stations, but all the signal switching and meters and sensors and stuff will be off the shelf so if it breaks you just buy another and swap it out. Also all the info needed to interact with those pieces of equipment are in the manuals, not in some README file someone wrote 15 years ago before they disappeared. Just use the drivers/software from the manufacturer as much as possible. I still make custom fixture boards for stuff I think I will need a lot of test stations for but if I wasn't also the production engineer, I probably wouldn't do that as much.Here is another tip. Any connectors on your fixture that get plugged into your product, make these easily replaceable. Like on their own board cabled into the rest of the fixture type replaceable. Connectors are not usually rated for the number of cycles a test fixture will see and they will wear out and it will suck if it's hard to replace them.

author: phil from seattle
author_rank: Super Contributor
timestamp: March 15, 2025, 05:33:58 pm
content: Quote from: Smokey on March 15, 2025, 06:20:54 amGood advice. I'm using a teensy with a simple PCB for the test controller. I expect the test base to wear out (pogo pins) so will have multiple of that. Hope I get at least 1000 tests out of each one. Standard IDC cable/connectors. Gold plating on the connectors. Linux on a RasPi to drive the whole thing and report Pass/Fail.

author: Fire Doger
author_rank: Regular Contributor
timestamp: March 16, 2025, 12:32:47 pm
content: The place where I work has 2 assembly lines, and 0 pogo testing. We have testing firmware for each product which tests the functionalities.Keep in mind that your tests are testing solder joints. PCB testing (flying probes) should be asked to be done by pcb manufacturer.If you have for example CANBus, you connect the DUT to a working bus and if it works that equals that all connections in relation to canbus are ok.Similar "selftest" tests can be performed for RAM, Flash, Eeprom, microSD, flash leds, etc...You can improve this by pogo on IO connectors but they are usually big and clunky connectors so you can use bigger pogo that are more reliable.I have noticed at embedded world that there is a growing company group with low cost 3D printed jigs which may be useful for you.https://www.eloprint.com/https://www.pinplate.si/en/Also for pogo there are pogo "sockets". The base is the expensive part. if a pogo wears out you just replace the pogo. No need to have multiple fixtures.Also pogo don't wear out that easily, tag connect connectors for example has programmed hundred of thousands of boards, the plastic has gone, the cables replaced a couple of times, but pogo are just fine.Pogo manufacturer with fixture too (more professional grade):https://ingun.com/en-GB/products/test-probes/ict-fct-in-circuit-test-and-function-test/

author: meshtron
author_rank: Regular Contributor
timestamp: March 16, 2025, 09:26:59 pm
content: Interesting, I hadn't thought about special "testing" firmware, that makes a lot of sense. On my first product, I'm already really tight on memory so this might be the perfect approach so long as I'm successful in automating the flash/test part (which seems pretty doable).Thanks for the ideas!

author: meshtron
author_rank: Regular Contributor
timestamp: April 25, 2025, 10:56:15 pm
content: Officially adding tariff resilience to the list of reasons I want to do my own assembly. For my own products, these (insane, hopefully mostly temporary) tariffs caused my BOM cost to go from $34 to $37.85. If I had to pay tariffs on all the parts plus the assembly thereof, instead of ~10% my cost would've gone up by almost 80%.For my day job employer, first batch of some new production LED boards just went from $3k to $8500 which likely kills the entire business case for having them. Exploring US assembly options but I'm not optimistic.Yes, these tariffs are temporary but now that there's an easy, judicially-approved method for any administration in the US to unilaterally impose tariffs at their whim, it's not a problem that will be permanently gone maybe ever. Dumb.

author: phil from seattle
author_rank: Super Contributor
timestamp: April 29, 2025, 08:56:27 pm
content: Yeah, at what ever the tariffs are today, a lot of products become uneconomic. I'm sure they will change in a month or two when both sides realize it is in neither's best interest.Sorry I missed this thread when you originally posted, but have you looked into getting preprogrammed MCUs? Most majors offer that as a service. With a little built in self-test, you might be able to do a reasonable amount of testing with a minimal test jig.

author: meshtron
author_rank: Regular Contributor
timestamp: April 30, 2025, 05:30:56 pm
content: I haven't looked into pre-programmed MCUs because I've decided instead to settle on a hoss of an MCU to become the "standard" (STM32G474) for all our products. I can make it feasible by buying those in decent-ish volume, but will have to flash them per-thing.BUT, I'm pretty happy with the progress I've made (in planning, not yet building) out some flash/test stations and workflows. I think I can get decently efficient and quite fast at it without spending a ton. Already have parts to build a RPi-4 based, touch-screen and receipt-printer enabled test stand. I think the root of my problem before (with pins making sketchy contact) was non-vertical placement and not enough pressure/rigidity.