Hi Previously I've done a video on Uh Design for manufacturing your circuit board I.E How to mount it in a panel? uh, such as this for production and I'll link that in down below. it's been incredibly popular one of my most popular videos, but uh, so this is kind of a followup to that in how to add some automated test functionality to your particular panel to help in testing your final product. Because what people will do uh with their panels? If they're you know, a beginner, or they're being lazy, or they're not doing a huge run, and they don't want to invest in an automated test system that typically they'll uh, put it in a panel like this. This is pretty essential for when you're getting your boards manufactured, especially for small boards like this.

So uh, when it goes through the pick and place machine, instead of just manufacturing one tiny board at a time like that, you can actually pick and place all the parts at once, so there's real big advantages to doing that. and most people do that if they going for any sort of reasonable, uh, quantity, putting them through a pick and place machine. but uh, often. uh, unless you're doing, you know, tens of thousands or hundreds of thousands, you don't often invest in an automated test system to actually plug onto the thing.

But uh, as we'll see today, even for my microcurrent, I'm doing a new version of this and I thought I'd just add a test connector on the side of my panel here just to help out. and just you know, smooth that testing process. even though I'm not making tens of thousands of these things. Um, it really as simple to add just some basic features to your panel just to simplify your testing.

So let's go now. Here's an example of an At Connector Automated Test Equipment connector designed into to a commercial product and uh, this is something that I worked on a few years back and you'll see that on the edge of the product here, which is actually hidden uh, normally hidden to the user by way of uh, you know, Moun rails and things like that. You don't ordinarily see this, but it's got a card Ed PCI connector built into there. Yes, it's the same PCI connector.

uh, you'll find in your PC Now the good thing about Uh PCI connectors is that you know they're standardized. They're good for a large number of insertions. In terms of, uh, you know, the test connector. If you're testing thousands of these boards, you don't want to have to replace your connectors all the time.

and we'll uh, see that in a minute. And the other good thing about large PCI connector like this, it has a Lot of connections. It's got all those on the bottom as well. So and you can transfer power and lots and lots of data and test signals.

And that's exactly what happened on this particular product. We sort of, uh, in the design process of the product, routed out all Of these signals out of here sort of. you know, in parallel with all sorts of other stuff and there were dedicated IO pins coming from the processor and Fpga to uh enable this functionality which was designed in to the product from day one. Now of course we could have just used a you know .1 in header or something like that and that's okay.

If your board is designed to be uh, you know is is not going to be visible to the public then that's fine. You can design it in. But the thing about uh, header connectors and other offboard interconnect connectors is that you got to physically plug a cable into them and that's a step that can go wrong. You can bend pins, it's messy, it takes time.

So this card Ed PCI connector. What this allowed us to do is actually Mount this board on a sliding rail system and here's one that I uh, handbuilt. You just slide the board on top and then uh with a big handle on the side. just push it into a purpose designed uh test jig board on the side there with the PCI connector mounted on it and that works really well.

It's very quick, it's very simple, and uh, these card Edge connectors here. You don't need a really really hard gold plating on these like you would on a normal Uh expansion card for example cuz this is only designed to be used once during the Uh manufacturing test and then that's it. This connector is never used again so you wouldn't be wasting your money on uh, hard gold Edge pla in on those connectors there. So here's the automated test Board I designed for this thing and I've taped up a few things just to protect the innocent here.

and um, basically it had a uh processing uh module on here so it had its own local processing and it was designed to basically uh perform most of the testing in combination with the test special test script which was downloaded to the product under test that plugged in. So I had one big main board here which mounted on the Uh shazzy. I Just got some mounting points because you don't make many of these. Um, you don't really? You know this is not like a product you might make say five or 10 of these.

for a large production run or something like that you'll test. You know you'll have five or 10 operators or something like that testing boards as they come off the production line. So that's about the number we had here and it's got various programming interfaces you know, power off on. it's just powered from an external plug pack, all its own local regulation and down the bottom here.

it's uh, most interestingly it has all of the um past fail functionality down here so all the different tests which will step through and some you know, some spare just in case, um at the end of it and it's got past fail leads for each one so these would all be populated. You know, red leads for fail, green leads for pass. So um, however many minutes it took it, it just tick through each test and you see each lead come up red or green after you press the test button. it basically handled everything.

There's a switch on here to apply power to the device under test. Here here's the test interface connectors over here. we'll take a look at had uh. it can measure the board current as well.

You can see a current uh, shunt resistor down. oh sorry, that's a that's a poly switch to protect the board from any uh overload. Then it's got a current sense resistor Little Current sense amplify so it can actually measure the current. That's all uh part of the test as well.

It's going to have a little uh LCD on here so you know just a two line by 16 character thing so that you can get uh status. That's pretty handy. And as I mentioned before, the number of insertions because these test jigs have a finite lifetime of the test connector over here here. Uh, you basically look at the data sheet for your connector and it might say a th000 ma in Cycles right? So you would? Maybe you wouldn't go that far.

You might go Okay, I'm going to set it to 500 so this would just be one of those little LCD counter modules that every time a board is tested, it just increments that counter by one and then once it gets to a uh set number, then you can, um, you know, stop it to testing or you can warn the operator or whatever to uh, change this test board and the test interface. Uh boards over here Here we go. Just start. Point basically converts that PCI connector on the side to1 in ribbon headers which then connect over to the main board here so it allows you to mount this test interface.

uh Board Test connector board vertically so that uh, you know, on that sliding test you I had there and then just easily connect over to the 0.1 in header connectors. And there's a test board which we plugged into the product under test to enable some uh loop backs and other functionality. But that's just an example of a typical automated uh test jig for a specific product. And if you're serious about uh production of any product, then an automated Uh test system like this is absolutely vital to ensure that you know speedy and quick testing of your product on test.

Especially, you know, trying to build a lowcost product. For example, you don't want to manufacture your product for a 100 bucks and then it cost you $100 in time to test the thing. Um, you know, even it cheap, uh, labor rates. If there a lot of testing that needs to be done for the thing, then, or you're even 10 bucks worth of testing, you want to minimize that time.

So if you design uh, testing into your product to begin with OR into your production panel, then that can really help a lot. In this case, it wasn't a production panel, it was the finished board. So with my previous microcurrent design, I've done videos which I linking down below of me actually uh, testing this thing and it was quite timec consuming cuz yeah, I produced it on a panel like this, which is efficient for manufacturing of course. uh, 5x2 10 boards total, you know, I'm lowering my cost there.

but in terms of testing, these things had to be individually broken out of here and then tested at the individual board level after inserting the battery on the back for each one for example, and then you've got to operate it. Then you got to plug all the leads in and out. In this case, I've only got a small number of connections, two at the top, two at the bottom here, but even that would be a pain in the ass to plug leads in those four leads and you got to do it for each unit. So that's why I Shown this in a previous video where I designed this little uh test J where I could just take my finished board and just plug it on top like that, hold it down and then uh, run the test and that was it.

It was, you know, reasonably efficient, but uh still. I had to go through and manually flick the switches on each one and it didn't allow me to. you know, test. uh, some things cuz it was powered from the battery under test and things like that.

so it was okay. that really reduced my production time. but uh, considering I'm doing a new version of this board, I would like to design a bit of functionality into this panel so that I can possibly test all 10 at once while they're in the panel and without having to plug the power into each particular one because you may like there's nothing worse than if you're not shipping this product because it contains the Lithium battery. then nothing worse than having to insert the battery, do the test, and then remove the battery again before you ship the product.

What a pain in the ass. Uh, you're just wasting time and money. So what I'm going to do is uh, integrate some functionality into this panel. So and into my individual bare board so that I can do uh, you know, not quite test 10 at once.

it's not going to be that automated. I'm not going to go to town on this thing for various reasons, but just allow me to speed up the production a little bit more over this dinky chit test jig I've got here. So remember when you get a panel manufactured like this, a panel is just part of the Uh PCB so you can put tracers. you can even put circuitry, connectors, and all sorts of stuff on here outside your product.

and you can get signals on and off your board. But in this particular case, I didn't I actually. uh VG groved these old boards here. and if you do VG Groving.

Yeah, it's cheap and simple. You can just snap off your boards and everything. but you can't route signals across here either top or bottom because that Vgr that just you know the wheel comes along and just saws out all of your traces. They'd be cut.

So we have to, uh convert this thing to having uh breakout tabs. And here's not quite my uh finished product. but it has got the uh breakout tabs like this. so even though there's you know, there's not much room in there.

I Can actually route out a trace or two top and bottom side of the board out of these little tabs here. So as you can see, there's not much room in here. but there certainly is enough room to rate out route out a single you know, 10 th trace or something out of there and then down both top and bottom side. But because this is a front panel board, you know, the look and feel of this thing is quite important.

So it's not like I can bring a VR up here and then you know route out a signal top side like that. it's just going to ruin the look and you know finish of the front panel of the product. So um, on this particular design I am limited to the four corners on the bottom now I could add extra breakout tab here for example, but once again, that doesn't cut out very nicely. I'd have to do some mouse bites in there as they're called and sort of dig into the product a bit and you just don't get a nice smooth finish.

but on the corners like this when I break them out with a pair of side Cutters it works really well so you know, just for functionality uh, and and appearance sake. I'm going to limit myself to just four tabs on the corners on the bottom side, so that means I'm probably only going to be able to get out a single trace on there I Don't want to push my luck so I'm pretty much limited to four traces coming in and out of each particular board in this case. Now, one thing you have to be careful of is that these routing paths here aren't exactly uh, precise. So well you can actually Define them as precise, but typically the manufacturer will use whatever routing bit uh, you know it might be 2.4 mm standard routing size in my case I Do know that so I have rout.

so I have specified this channel as 2.4 mm wide. so I I'm pretty confident how much space I have in there for a trace and really, you know it shouldn't eat it. but just be aware that there is, uh, quite some manufacturing tolerance in there. It may not be exactly as you specify unless you really handhold your uh Bebo manufacturer to get it.

uh, right. You know if you start pushing two and three traces down there, you know 5 TH or something like that traces, you can be in trouble. Just be aware of that. Last thing you want is for the routing tool to come along here and just you know that Trace bin right on the edge and just tear it off or uh, drill all the way through it.

And if you are going to be a rebel and put like, uh, several traces through here, generally you'd only put one Trace through each uh Mouse bite. If you did a mouse bite, you'd have a couple of little or you'd put multiple Uh Vas along there little holes so that you could actually cut it out. You might put one Trace between there, but if you're really desperate, you might try and squeeze in uh, two traces in there. Just be careful of that because if you then get in there with your side Cutters and cut it off, you can accidentally short out your tracks and that can ruin your day.

So let's have a look at my new circuit here and see what test functionality I can include in this thing now I wouldn't mind uh, basically being able to uh, replace the battery here. so I can power the board all the boards, all 10 boards on that panel of course. mandatory I have to measure the output voltage here and I've got my input current over here so you know, um, really? ideally I'd want uh, six connections like this. so I can inject a test current, measure the output voltage, and also power the thing under test cuz remember that I've got a battery low detection uh system here so I want to? It' be nice to be able to uh test that for example.

So you know, feeding like 3 volts and make sure the lead lights drop it down to 2.65 Vols under the 2.7 volt limit and ensure that the lead goes out. Things like that. so uh, really I need six connections But as I said, I've only got four there. So I'm a bit limited into what I can do now of course.

uh it. My first thought was, of course, well I can hook the current in series of all the boards so I can feed in one uh, constant current source and then Loop through series like this. all of the 10 boards. on the particular panel, but unfortunately because of the common output ground here, you can't I can't just do that.

This is not a floating current input so unfortunately that plan unless I want to uh, my test board to be able that plugs into this panel. uh to be able to uh, switch current into each board separately so that's you know that's a bit messy. So um, especially at the low currents. We're talking about switching the low currents and things like that and you know I would I would do that? I would have be testing all six things like this and have a nice current uh switching system if I was manufacturing tens of thousands of these things and you know I wanted to do it properly.

But really, this is just like a quick and dirty uh thing to you know, I may only be manufacturing hundreds or a couple of thousand of these things. so I don't want to go to town on this and gild the Lily So what I'll do is I'll just uh tap the output voltage of course that's mandatory and I'll power the board. So there you go. I got my four connections positive negative power the board so the one voltage will go in parallel to all 10 boards and then the output voltage.

Of course the Common's all the same but then I need to tap out the Uh 10 10 boards on the panel. So 10 individual output voltages here and then I can just run around and plug in. So when I've plugged my test connector into this panel, I just run around and then plug uh the test current into each one. Yeah, it's a manual work with a cable, but hey, you know it's good enough.

It's still going to take save a a lot of time over this clunky thing, so that will be the plan. I'll have a test connector on the side of the board here and I'll route out the output voltage signals through the tabs up here and all the way around the outside of my panel. back to this one. you know, large 15 or 20 pin test connector over here and then uh, that'll feed.

allow me to feed in the voltage, power up all these boards without having to plug the batteries on the back. I can test the uh low battery voltage here and I can also then just go around with a cable and go boop boop boop boop like it literally will be that quick. just touch it on like that and I'll have some red green leads uh on my board just like I did over here on this board here. I'll just have a whole bunch of like 10 red green leads which will just uh pass fail the current into the board like this.

Easy! So I've just done a quick Dave CAD doodle here of uh, what? my test board will be. It'll have like a 14 way test connector here I need 13 connection so just make it 14 or 15 way just A.1 in header for example. Then it's got uh, ground, reference ground, and those 10 output voltages from the 10 individual boards. and then they just go into a Uh window detector here which then lights up a you know, a red green, uh light based on a reference voltage for a particular know uh test current you know might generate.

you know, one for a nominal, like one volt output or something so that might be 1vt uh reference voltage. Of course it's going to be a plus minus because it's a window detector so there'd be the intolerance in there of you know, 0.05% or something like that I would set it to whatever tolerance I require for testing. So this would be a you know, a real expensive voltage reference. real expensive Precision resistors on here.

but because you only have to make one of these boards, you know, not a big deal. and then that reference voltage can also uh be used to generate a constant current source as well. So I probably don't even need to use an external uh, my Keithly constant current sources anymore I Can sort of build this in and calibrate this thing and you can have trim pots on this board and you could you know, test it and trim it uh perfectly cuz I only need one board, it's not too hard and then I can generate the test currencies go off to Banana Jacks and then as I said, I can just you know, walk around bang bang bang bang and then the Uh leads light up on the 10 channels. I can have a selectable 3vt and 2.6 volt voltage source to detect my low battery there and that's pretty much all there is to it.

Although I might also want Uh in here. for example, I might want to add in a little a little current sense um, uh, shunt and you know then I can measure the test current as I switch on the individual boards so I can go around you know, switch one board on and it' be one no and current. For example I can even have like a panel meter on the board as I did for that other uh at board I showed you know, switch it on, you're going to get you know 1 milliamp current draw plus minus something, you'll get you know, switch the next one on in parallel or uh, switch that one back off and you can measure the total current to make sure there's no overloads on there. I don't know if I do that, it's not.

you know. Really a big deal. CU If you get your output voltages pretty much, there's going to be uh, no overload conditions with such a simple circuit like this. but there you go.

Very easy test board. You just build one of those and bingo you can uh in store you can either do it inhouse which I may do for some or then I might give this uh test board once I manufacture it to the subcontract assembler, then get them to test the boards as soon as they come off the the production line and then you do some test documentation to go along with this. to just explain step by step clearly to The Operators uh, how to test these boards and what to look for. But as I said, if I was really going to town and doing this professionally for you know, tens of thousands or hundreds, thousands of boards, I you know I'd automate this I'd ensure that I could feed the test current into the test connector and I'd have automated switching on here.

I'd have a microcontroller and a test button which sort of ran through an automated sequence of tests and then just gave one big uh pass. fail on there. And the other thing you want is when you got your 10 Leads Here Switching on, you want to give those a number and of course, you want to have an Associated number printed on your panel so you know exactly which board failed. Uh, lights up.

So typically you'd uh, you know, put a silk screen label there you know, 1, 2, 3, 4, 5 Etc then you'd take off some solder MKS there so that you can mark it with a uh, you know, a red marker pen or something like that that that boards fail or you know they could come along with one. you know, a red DOT sticker or something like that. Not very V visible on a red board. but you know each Uh test House has their own way of doing that and on a fully automated jig.

of course, you would, uh, probably break out the Uh connectors as well like this so that you could automate those cuz there's nothing worse than having to go along and manually flicking switches for various ranges and and testing like that. So if you're really serious, you probably route out all those so that you could automate it with Uh relays or solid state switches or something like that. All right, let's actually take a quick look at my board here and just see what I'm going to do. I'm not actually going to go through the detail I'll just show you uh before and after.

basically I've got my schematic here: I Know that I want four test signals, two from the battery here and two from the voltage output over here. So let's take a look at my bear board. What I need to do is Route some traces on my bear board through to those uh through to the corners out here because this is just the individual board I haven't panelized it yet, but I still need to Route traces on my individual board Now this will vary how you exactly do this will vary totally depending on which uh PCB package you have and how it supports panelization of your board. This is alum designer that I'm using here, so other packages will vary and there are multiple ways to do it within here.

But anyway, here's my bottom layer here. Here's my battery uh, positive and negative terminals down here. So what I've done is I've routed this Trace out here down to this bottom right hand corner down here and I haven't I deliberately haven't uh, taken it all the way to the edge like that. If I just want to get a single board manufactured, then uh I can, uh, you know then that's just going to work fine.

but then I'll bring my Trace in here on the panel side and that'll just automatically join up as we'll see in a minute and then I've got my other uh one over here routed down here to the bottom right hand side so that's easy. And then my output signals were really easy CU they they were my two uh, terminal binding posts up here so I just routed those out to the corners and I've just got them going out so they're my four test signals and as I said nothing on the top layer because that's going to be my visual uh, you know thing I don't I you know I don't want to ruin that um at all in terms of uh, you know, um, spoiling the look and feel of my um front panel board so it'll just be on the bottom there. So anyway, if we go over to our panel, let's take a look here. Now here is my panel board and oh, it's flipped.

sorry about that. I'll just flip it back and this is how I've done it. 5x2 I could have made a larger panel, but hey, 10's a nice round number. Nice little compact board.

it's going to uh, fit with any manufacturer and basically, um, I've done a video on this uh before so I won't go into the details but I've just specified my routing path here basically and uh, that's a 2.4 mm route and then I've just stopped short there and I just put a manual note on there to let the beerboard manufacturer know that uh, they are to Route out that and to them, it's pretty obvious what to actually do I don't have to give any additional notes, they just, you know, are so used to these sort of things it's really obvious. and uh, of course this actually panales this thing for me. it's a panelization routine inside here so it just duplicates my single board uh, 10 times. but if you got a package that doesn't support that, then you would have to manually cut and place.

But anyway. Um, so that is my bed board without any test functionality at all. Of course. I've got my fiducials down here and my tooling holes as well.

They're important as I've mentioned in previous videos, but now here's one. I've prepared earlier. This has my test connector on the side here. So what I've done is I've just got a a 15 way or 14 way 0.1 in right angle pin header here which they'll uh, solder on at the assembly stage it doesn't you know, cost a huge amount just to hand solder that that connector on and I've basically got traces running out the tops and bottom corners and these boards to line up with the other traces.

So let's go to the bottom layer here. I Just switch that on and I've got the trace just coming through the little breakout tab there and just going in here. So when I generate the Gerbers it'll automatically join up with the existing Trace in here. So I've just got that separate Trace going to the output, the positive output connector of each board like that, and then the negative one.

I've just got that, uh, going to the uh top layer and that's just a common trace on the top layer there. so that yeah, there we go. and on the top of course I've numbered them as well. 54 3, 2, 1 I've removed some solder mask there just so that you could write uh something there easily with the marker and I've done that for all of these boards.

and I've bought all those signals back to the test connector the battery here. these two pins here are just going parallel to uh here we go down to the bottom corner. I've done exactly the same thing down here as I did before I just have the trace going through there and the uh, positive or negative I think it is Trace going through the other side and that's it. That's how I've um, added some production functionality to my otherwise uh, wasted panel because usually a panel all it's there for is just a physical mounting frame with just some you know, tooling holes just to hold the board in place inside the pick and place machine and the fiducials visual alignment fiducials to line up the uh pick and place head and that's all it is.

But we have actually added some stuff and if I wanted to I could add active circuitry onto this panel. No problems at all. and now I haven't gone to the effort to produce a separate schematic for this panel. but if you really doing it seriously and you want to design realle, check so I can't design realle check this uh panel board because it's so simple I don't really have to.

The risk of uh me goofing something up is quite low although Murphy's Law you know how it goes. But anyway, if you want to design real, check that. You typically have a schematic Associated that and there's various ways to do that so you would have individual board schematics and then a panel level uh, schematic as well if you really going to town on this thing. but that's all there is to it.

So my test board will just mate with a female Um header over on this side and bang. Just plugs in the side. and now I can power all those boards at once and also access the output test signals. And here are the generated Gerber files which I've done uh earlier.

I could have done it, just live. but uh, let's zoom in on this sucker and see what we get here. Now as you can see when I zoom in. Oh, when I zoom in, something's going on there.

Oh, something buggy there. no tra like. you can't see the uh routing paths here, but as you can see, it's now. These traces are now joined up on my board so the paddle ones have just automatically because I've overlaid them one on top of the other automatically just joined up at the Gerber layer like that.

So now my Gerber is just fine and dandy. I think that artifact might be my screen capture program doing something I don't know. Um, but yeah, all those tracers are now joined in there and I've got a full production test. Uh, production ready panel.

Fantastic. So there. you go. That's just.

uh, several simple options for uh production testing a panelized uh product like this. Very simple to implement, just you know. Something basic like this that can really pay div ends. Uh, come test time.

So I hope you enjoyed that. And as I said before, all of the uh previous videos which are uh related to this will be linked in down below. so be sure to check those out if you haven't done that already. And if you want to discuss this best place to do it is over on the EV blog Forum because the new YouTube comment system sucks ass.

Catch you next time.