Hi. This is part two of the Paduk Three Cent Micro Controller Programming series where we build up open source, uh, programmer hardware and install the open source software to program these Three Cent Micro controllers. So part two here is just going to cover assembling this Pcb. So there's lots of like soldering and assembly tips and stuff like that.

Let's go a little while later. all your stuff just magically appears Pcbs and all your parts are baggied straight from Willy Wonka's Chocolate Factory. All right, let's have a look at our Pcb here using our Tagano and we're in like Flynn. Check it out, All right.

Doesn't that look neato? Unfortunately, of course there's no silk screen overlay, so we have to, uh, like, use an overlay diagram if we're going to assemble this sucker. And let's just, uh, check, we didn't get any of that gold flash rubbish. So let's just go in and check out the alignment on the solder mask expansion. You can see we've got our solder mask going between pads there.

No worries, that's pretty good. That's a reasonable alignment for a Proto like this. No problems whatsoever. There's no, you know they're not overhanging the pads or you could argue.

and there's a little bit of overhang on the pad there. But you know, nothing near right home to your mum about for however couple of dollars we paid for these things. Um, it's just yeah, it's just fine. And the registration on the villas? hey, look, bang on.

look at that smack in the middle. No wackers. Um, and of course this board is uh, has tented vias. Which means that the solder mask comes over the veal like that.

Um, no, they're not actually plugged. It's just that the solder mask happens. You can't actually get plugged vias, that's a separate process. This is just the solder mask just goes over the top and sometimes you get it to like.

So is that got a little pinhole in it. Sometimes you get like complete coverage like that and these ones down here. Other times you'll get it. You'll actually get a hole through there.

Do we actually have a hole through there? Do we actually have light coming through that hole? No, I don't think so. No. Anyway, sometimes you get it going through and sometimes you don't Just depends on how the dice rolls. Anyway, that board looks pretty decent.

More than decent enough for a proto. When I was a boy, you couldn't even get something like this for a hundred bucks, let alone a couple of bucks. You know if you paid 100 bucks and you'd get a it was a miracle when paid 100 bucks and you could get like a tin plate board. Now this solder mask rubbish your tin plate.

So yeah, Anyway, that's good enough for Australia. So what do we need for this? Well, we need our schematic that's always handy. Then we need our overlay diagram. Yes, the distortion in that, uh, barrel distortion there is caused by the lens on the tagana.

It doesn't go away unless I zoom. You know, All right, it's still there, still a little bit there, but you know you zoom in near enough and then it's all right. There we go. Zoom in a long way before it actually becomes fine.

That's to do with the lens that I've got on this thing because this thing's got like 30 times Zoom. It is Huge. I mean, this is why I can go from a wide, huge, wide view like this with my hands to all the way in. And this is not digital zoom.

This is optical zoom. Thank you very much. and that's the price you pay for all that zoomty goodness. Anyway, there you go.

gotta have our overlay and we got our bill of materials just in case you know you want to do some cross references and stuff like that. Um, we don't actually have the designator in here, so it's not entirely useful. But anyway, you might want to do a cross reference and the age-old debate of course, whether or not you should actually put values on the silk screen overlay. in this particular case.

Um, you didn't want this overlay because you wouldn't want to get this overlay printed because this, uh, the designator here would be smack on the pads and you don't want your, um, your silk screen overlay overlaying your pads? That's going to ruin your day. So like you know, this has been optimized for not for printing on the board, but it's been optimized for uh, you know, assembly. But yeah, there's a bunch of fan boys out there who love putting the component designator and the value on there, and for assembly and for troubleshooting and repair and stuff like that. Good idea.

So with this board, the first thing I'll put on because it's the biggest and it's just super satisfying to do it up front. Put the chippy on first, and especially if you've got lots of parts, like really surrounding the chips like this, like close to the pins. If you have lots of bypass caps, there's not really that case here. you could argue this one's a little bit close.

It's just that if you've got, if you put all those passive parts on first around your chip, then it can be hard to get in there. and do you know, get your iron in. You've got to come in at a much higher angle like that. Rather than just rest your hand on the bench like that and come in at your normal angle, you've got to tilt it right up.

and that can be annoying and that can impact your soldering technique. All right. There's our little chippy, so we want it according to the diagram, we want it like that: up in the top, right, pin one up in the top, right corner. Beauty.

all right before anyone asks. I'm using my Pace Ads 200i in here because I just like it. It's very nice and I'm using 0.38 millimeter uh tin copper. I eat lead free solder so it's a 5 core flux multi-core brand and up.

I like using fine solder for surface mount stuff like this because you can just feed Much finer control than if you use like Point Eight millimeter stuff like that. you can just you know, when you feed in onto the oh, you can see the heat, the shimmer in the video from the heat. I love it anyway. Um yeah, you can just feed in a more precise control over that solder.

So there we go. It's maybe a bit more suitable although you can't use. Big tip, no workers. and no, I'm not using any Pcb holder or anything like that.

See, even with this tiny solder, look at the amount of solder that we've put on that pad already. No, I'm not using any uh, Pcb holder at all. So there you go. We've tacked wow, a little bit off.

There you go, that's a bit better. it's a bit how you doing before there you go, attack down one pin and then you just want to go in the opposite corner like this and tack that down as well. Just tuck that one down there like that and bingo. Chippity-doo-dah is not going to move anymore.

So now we can get in there and we can solder so I'll get my flux. I just use a Chem Tools uh local brand. no clean flux pen. does the job.

Some flux. There we go. We can go all the way around if you want. Just put some flux on there so that our joints are going to be cleaner.

All right. Should we do drag soldering or not? Oh yeah, why not? Look, I'll go to my well based tip and there we go. You can see that's got a well in there and that helps the surface tension drag the solder away. Oh, some daggies had some daggies.

Hang on. don't know where that came from. There we go. so we'll just feed some solder into there like that until it bulges out a little bit.

Start on the unsoldered side, shall we? And there we go that is soldered. Got a little bit of dag left over there that'll just fall off. No workers there we go. Fortunately, our chippy's not perfectly lined up, but anyway, no workers that is actually soldered.

Believe it or not, it's terrible. Muriel, let's put our solder in there and then let's just go along here and jump. There we go. That looks sweet as once again, all those little dags will clean up later.

Probably would have done better without the wheelbase tip. I think I don't know. Soldering looks terrible up close. Like really magnified.

It's always better from a distance. Next up well and do the most prolific uh thing. so 100 end capacitors. I just yeah, we've got 12 of them.

So just get 12 out of the bag and then go around and populate them. And then if you actually count 12, then you can't. I get it wrong, if you've got one left over, you know you missed one somewhere. And be careful when you tip these out because these things can fling around everywhere and you can come a gutter.

You can lose one trap for young players. So what you want to do now is go around and just tack one side of course the right hand side because I'm right-handed So I attack the right-hand side of all of the capacitor pads all 12 of them first and then because if you do it one by one, it's just. it's just much harder. So yeah, I believe that one there.

so just put a bit of solder on there is that one there. In fact, you could argue that it's uh, best to just simply go and do everything. Really like. Go and do every single pad, so then you'll be ready and rearing to place those components.

Some people don't like to do that, but once again, components can get in the way. Well, a little bit too much solder on the previous pad there. Rather than just try and find them all, maybe just go in and do them all. That was a thermal mass thing that was.

Uh yeah, the tip is actually too small. but just be consistent if you're doing top side, do top side for all the components and you know, left for all the others, etc. Oh oh no. I gift it.

That one goes in that direction. That one goes in that direction. Oops. Sometimes you do that.

That's what happens when you don't have your silk screen overlay. You get your camera guts are you don't know what's the right way up? We'll do that for our Sop 23 package there. No wackers even for our big daddy Jobby up there and do that. And these two tiny little tiny little deities.

Itty bitty and uh, we won't worry, we are. Well, okay, yes we will. We'll do a one pin on that Us: oh no, that's uh. do that.

Usb is. um, it's got holes there. a Usb connector? Um, shouldn't have done that. Oh well.

it doesn't matter and might as well do it for the inductor up there too. Now normally I actually wouldn't be. uh, doing this on the tagano with a digital um screen like this. I'd ever be using my mantis or nothing at all.

Um, just be using my eyes, my mark one eyeball. But because I've got to shoot this video I've you know the the the Tagano is the best way to do it. The camera inside the mantis absolutely sucks for video. So yeah, the absolutely kills it.

So there we go. I think we've got um solder on all our pads now we can go around and place some of our caps. Where do we want to go here? Where was one? There was one C12 down here? That's definitely one. So we'll just place our cap on there Like that.

I would go around and solder them all in one pass later and then do a second, uh, visual inspection. Uh, pass. After that. That one's most likely a bypass cap because it's going to the ground plane there.

Am I right? C2? I think Irma? Yep. C2. No workers. So let's get C2.

There we go. You can do this really fast if you know where they all are. like. if you're doing it like I am, you've got to like punch, hunt, and pick uh to find the damn things.

C8. You know, if you're assembling a whole bunch of boards, you'd get used to what's what. And there we go. Gotta have a pair of nice pair of fine tweezers And they've got to be wide enough.

Like to place to get over chips like that as well. By the way. So you know, Um, you've got to have multiple. Like, get get different types of tweezers.

you need bent ones and all sorts of fancy pantsy ones. Yeah, this. um. chisel.

This tiny little chisel tip? I don't know. Like is it like half millimeter chisel or some point eight millimeter chisel or something? It's probably like it's too small. Uh, these are O603 uh parts. and I just don't have the other one.

Another one to hand. I could find it and put it in there, but oh, maybe that one there is probably more suited. I'd say that one is a 1 16. I don't know.

What's that in Bloody Metric almost tombstoned in there. This is the problem with um, like digital microscopes like this, it's hard to see because they're not three-dimensional It's hard to see whether or not um, components tombstone. It's much better under a mantis or with your eyes. Okay, sorry, I'm not sure why the uh, tagano capture froze there, but anyway, lost a bit of material.

Now we'll do the S08 and I swear I've been spending at least half of my time just finding the location of parts. Wow, Those pads are big, very generous. um left a lot of, uh, generously left, a lot of solder look and I still can't find where that 4.7 mic goes. I swear like it'll come out in the wash, but it's just.

it's really annoying to, uh, you know, just have to spend most of your time just finding parts on the board where to actually place them. And for something like this so-8 you wouldn't even bother to drag solder because it's so quick and easy just to do them one by one like that. Yeah, I didn't put any flux on there either, so I'm just relying on the solar flux anyway. If you don't know, um, the the Ip official Ipc standards for footprints, they come in um, small, normal and large size pads and basically it has to do with the you did the density of your board and if you've got a really dense board and it basically has to do with like how much pad like overlays like the end like this so that you can get your iron on.

And the good thing about having them extended long like this is that you can actually use this uh, use this extended bit as a test point for a flying probe tester. So they're actually very handy. So if you've got the space and you know your board's going to be flying probe tested, don't use like the small uh footprint pad which you'll have like you know they'll basically be no almost no pad extending over the end. There they're just very small footprint, very compact footprint so the uh, flying protester will have to come down onto the leg of the Ic and then it can slip off and short.

you know and do all sorts of things. So uh yeah, having larger pads like that is actually um, can be rather uh, handy. it's you know it's a luxury if you can afford it. and then the little sop 236 I have to tilt that you can see the tiny little dot in the top left-hand corner and that goes in there like that.

So yeah, don't don't rely on the text. Uh, always go by the actual dot and we've got our little diode and the end with the lines on it Like that. That is the cathode up and nicely there. Look at that.

Beautiful. Now here's where you can really come a gutter with leads. Look at these little suckers. Always measure them There we go.

So the negative is I.e the cathode is the one that although this one has a green line, that one necessarily doesn't But uh, yeah, so that end closer to the internal die, There is the negative end. Now here's the interesting thing is that you can't tell from the overlay which way around that lead goes. Here's the three Leds. Got a chamfer on there? What does the chamfer mean? Well, could actually mean don't rely on what that chamfer means because there is no physical embodiment of that chamfer on these leads, right? So on other types of other physical types of leads, they may there may be.

So what does that sham for me? And well, you don't assume that it means anything. What you do is, you actually check out the Pcb. There's our three Leds, Here's our three resistors. And you see, the series resistor is, uh, going up to the positive rail here.

So if we have a look at our schematic here, you'll notice that there's the resistors up the top to the positive rail. There's our anode. There's our cathode, Cathode goes over to the chippy over here, and you can physically see that embodied on the Pcb. So this would be our cathode going off to the chip and the anode goes over there.

So bingo. I've got a flip because we said that in there was the cathode. so I'm gonna flip it around. Focus, your bastard, All right.

So I flip that around like that and yeah, we'll just take that over to there and we'll solder that in place. Be careful with leads, they really don't like heat. leads aren't very forgiving. There we go, And just for good measure for sanity, check There you go.

Make sure you got them in the right way. It's so easy to come a guts. especially. You know, if you go to nothing worse than going soldering down 100 leads and then realizing you've got them backwards, it happens.

Now it's time for some resistors. Now you should always put these in the same orientation. So why just because? It's good practice so that you can read and inspect later. And some people like to actually solder them upside down.

Like as in, like, like, literally flip them upside down just for shits and giggles. But there's actually a practical reason why some people will solder them upside down because when you pull them out of the uh tape like this, they could land either way, right? So if they land like that, some people just go, oh bugger, it. Just solder it in upside down. I couldn't be bothered flipping the little bastard there.

it is like, oh, and it just so happened to flip in the direct orientation. Murphy must be asleep today. But yeah, and so if you ever see them sold parts soldered upside down like that, you'll know why people just went. screw it.

Couldn't be bothered. Look at all the resistor values in here. One two three four five, six, seven different resistor values. Did we really need all those different values? Like just ask yourself when you're actually designing? Yeah, yeah, it could be very good reasons for it.

But try to consolidate resistor values if you can. It's really handy. You know it just means one extra one less reel you've got to put on your pick and place machine. And of course, for a manual assembly point of view, I've now got to, um, take open, crack, open seven different packets.

You know, pull back the tape, get out like this is a 10k resistor. There's one of them on the whole board. Thanks. All right, let's try and flip six of these suckers.

What do we get? Oh, five out of six. Ah, close. but no cigar. All right.

I was just going to put down a couple of my last resistors and I found that one I was supposed to put down was already populated. Even this one, this, uh, 20k one was actually in here. And it made sense because all these 20ks were bundled together and maybe that's why I thought it was okay and I'm so glad I didn't solder the other end. I'm going to do that as one last pass because then I had to take that out and move it over to there.

And it was trivial. It took like two seconds to do that. Um, but yeah, you're eventually going to come even on a simple board like this with, you know, this is hardly any parts at all, but with actually eight different types of resistors. you know odds are you're gonna like, you're gonna give one of them.

Now here's an interesting thing. Look at these little diodes here. Little Sod 523 packages. Real pain.

Look at the size of them in the tape there, and there's actually every second one in the tape. which is interesting. So the problem with look there's this board is not a dense board. There's absolutely no reason to use such a tiny package like the Sod 5, 2, 3.

Like this, because you'll have trouble. The little pick and place head will have trouble with these parts. Look, Oh, six, are these are actually smaller packages than O Six O three. They're kind of like down in the O Four 0402 region.

then that's you know. Okay, but there's no reason to use that. and like some, uh, depends on your assembly factory, some pick and place machines won't be as capable or most actually won't be as capable with O402s as they are with O603. So there's just no reason.

Like you just get like a lower, slightly lower yield. Oh, some manufacturers might go. oh we hate O402s or whatever you know, like a real you know, using real old gear or something like that. There's no reason to use such a tiny little diode like that.

Anyway, can you see the my ah, there we go. If we zoom in, we can see the marking on that. There it is tying a little cathode mark on their little line. But yeah, zoom out like this is where you need.

like there's no way you can see that you know you probably can't Maybe when I was younger I might be able to see that with my with my eye. But like if you get the light at the right, oh yeah I can. it's I'm just getting glare. Uh, just the lights at the right angle.

I can't see diddly squat when I'm using this. uh, the this Tagano microscope. I've got actually look at the microscope because the angle of the light comes down like this. It's up in here.

It's up in here and it shines down and then it's the perfect angle that it just gets in my eyes and I can't like. I can't see any of the markings on those resistors or anything. It's hopeless. That's not my eyes, it's it's that.

It's just the angle. All right. I've gotten to the point where I've put in all of my passives. Now, you don't want to put in something like a crystal and why they used a through-hole crystal there? I don't know.

Everything else is surface mount. Use a surface mount crystal doesn't make any sense. Um, if you're going to. Oh no, I just forgot three.

What happened to three resistors up the top there? All right. I know. the reason why I missed those uh, three 1k resistors for the Leds is because I don't actually have them. I can't find them here.

So I had all my resistor packets and I went right. I've gone through all my resistor packets, I assume I've placed all the parts and I come back and want one. No, um, they're missing. So maybe I didn't order them.

Maybe they weren't on the bomb or whatever. But um, yeah, yeah, I definitely haven't placed them because there's three of the only three on the bomb. and there's three I I'm missing on the board. So um, yeah, I'm missing part.

It doesn't matter. I've got a kit because it's a lead dropper resistor. Why use 1k? Um, when like it's popular value. so I'm going to use some 820 Ohms? No worries, don't use those much so you don't want to run out of my 1ks.

So there we go. 820 Ohms. Make the Leds a bit brighter. All right.

Now comes the time that we want to go. in and solder the ends of them. So if you've soldered like everything, say on the right hand side. If you're right soldered, then you know you've got to get everything on the left hand side.

And if you sold everything from the top, you know you got to get everything from the bottom. So hopefully if you go through the board, you should be able to just find them and tack them down. Just go systematically. Oh, that was a shocker.

Too much solder. Dave Ah, Absolute atroci. Ah, Terrible. Muriel.

Absolutely terrible. Anyway, you don't need any. uh. flux.

Um, for doing uh. the components just rely on the flux in the solder. Unfortunately, because, the angle of my eye and the things, um, focus in on my iron. And hopefully if you go reasonably.

sister, I'm I'm not. I'm I'm not being systematic here. Here's where. Like real pain to get down into that diode down in there.

He's He's really trouble. I've got to go near vertical on that iron to get down into that. That's yeah, that's really annoying. You got to think about stuff like that for hand soldering matters.

And here's where I don't like these digital microscopes like you know you're looking down on it. I mean look, I can. I can actually tilt this. can actually tilt it on an angle like that.

I can tilt the tagana so it kind of gives you like a like a just just a different angle on the because when you've got like a top down view, it's not that great. And here's why I didn't solder in the Usb connector. By the way. because then it would have been a pain to access those pads down in there.

Oh, that's a bit how you're doing that joint alignment on that resistor there. That's a shocker. Absolute shocker. And yeah, it's it's just things look a bit distorted when you've got it like that.

But if you straighten it back up vertical and you're looking down, you don't get any depth perception. It's really, you know. it's really quite annoying. Anyway, I think I'm done.

but this is where you want to go. get them on an angle and go in there and inspect. Do that under the mantis mantis is better inspection microscope by far and even though I don't need to, I'll just show you that if you are unsure about joints in there, you can just go in and like systematically reheat like that. you see that salt is actually flowing further up the leg.

there. they're already soldered, but you know, if you just wanted to touch them up, that's how you do it. And oh, one last inductor there because that is not going to work. Uh my um, the Dc to Dc converter is not going to work without that inductor.

Okay with these Usb connectors. I would actually recommend in just putting down some flux down on there because they can be a bit of a pain. In fact, probably even whack some on the pins. If you're feeling lucky, it's gonna be really hard to get the iron into these suckers.

So anyway, I'm going to that doesn't protrude through the board so we can tack down one of those pins to keep it in place. So there we go. That looks right there we go. I think she.

I think she flowed. I think she flowed. Yep, yep, she's holding in place. There you go, There we go.

No, yes, they are supposed to be shorted. Beautiful. You'll notice that there's no solder mask down between those pins either. so you really want to.

uh, be careful about bridging on these pins. It's really tricky to get in there to the extra pin. You almost have to heat up the one next to it. I could have got my smaller conical tip, but yeah, should be right.

Bobby Dazzler. Look at that. Ah, you could say that pin over there hasn't wetted actually. Now it has.

Ah, thing of beauty is a joy forever now the through-hole stuff and you'll see that the solder will wick down in there like that and it won't always go all the way through. This one's actually going to require a fair bit of heat. Now you'll see the solder wick down through the board once it's gone through. there we go.

It's gone a bit concave, so has it actually flown through to the other side? Or almost almost? Don't actually need to put any more on there. that's more than taken up, but that's now. Yeah, like more than enough. And same with those ones though.

Flow down into there That looks a bit messy, but should have actually flown a good lot of the way down in there. Yep. so I put the tactile switch and a little pin header on there. One tip with these, you see how these aren't really as tight as a nun's nasty.

They're loosey-goosey in there, and you can solder those at the wrong angle. So just a little tip in there? Actually go and get a dip chip and actually insert it into there, and that will physically hold them in place, perfectly lined up while you solder them. Then you just lift the chip back out and just for a bit of street cred, There you go. a Ui 709 Texas Instruments 37th Week 1978.

I just literally like that was just one of the first ones that came off my Um sponge at my you know, I like I obviously salvaged. I desoldered this when I was a kid. I would have desoldered this. Um, still comes in handy.

Just another tip: when you're laying out boards like this, look at the size of these annular rings. I.e how much exposed ring there is on each pad. It's not fall like why would you do that? This is not a high density board. There's absolutely no reason to do that whatsoever.

The thing about a small annulus ring like that is it's hard. then to get your soul, your eye, your tip sorry. You tip onto there to make contact with the pad so that you can then feed the solder onto it because you put your soldering iron on there. First you heat up your annulus ring and your um, component leg.

and then you solder that looks, oh no, that is that a trick? No yeah, that's a that. That's a shadow trick. It looks like there's a hole there, but I don't think there is. I think that's a light and shadow.

So yes. bigger annular rings please. There's absolutely no reason to go tight-ass I hate a small ring and there we go. It's like a bought one.

Just cleaned it up with some flux remover. It's still got some resisue and stuff left on there. So what we want to do now is um, before we power it up. Just you know, buzz a few things out to make sure like things like the power rail and stuff like that's not shorted so let's do that.

So first thing C6 sorry I don't have the schematic here to show you, but this one here. This is actually the input. You can see it coming over there like that, so this is actually the input cap. Make sure it's not shorted and it's not winner.

And a cap on the Uh 3 and 3.3 volt rail C5 Here There you go. That one's not shorted either. So both of our rails are not shorted. So winner.

We can power that up. Oh, did I say power that up? Well, we can't because we haven't programmed the thing. It's got nothing in it. So yeah, oops, you.