Hi just a quick follow-up video on the thermal oven I thought I'd uh, just shoot some video of me assembling one of these green microcurrent boards I got from PCB pool and uh yeah, there were a few uh issues with it which actually um, you know you wasn't supposed to happen. the uh quality of silk screen is supposed to be much better than that, they assure me. and they ordinarily, uh, that shouldn't have happened and they would have actually replaced that and ordinarily, they wouldn't have sent a single uh, um, paste stencil like this. it would have been the full panel paste stencil.

Anyway, I think they are sending me another one, but I just wanted to um, test that I could uh Reflow a microcurrent board in my new uh thermal oven and um, you know there's no issues at all cuz you know, who knows, there might be uh, thermal issues with the uh Parts uh for example, you know all of all the Precision components I want to make sure they're still in Spec after their reflowed in my thermal of and I'm pretty confident in the thermal oven now. although I have to play around with using a uh, just a sheet of copper in here as I'll explain uh later but uh yeah, I'll just assemble one I won't do four because as I said, I' I'd have to cut the stencil up and well I just I'll just do one to uh uh, get a feel for it because this is not going to be my final design. I've made a a couple of tiny little tweaks not actually, uh, circuit tweaks, just in terms of um, some hole sizes and uh, silk screen and uh uh, stuff like that to the final version which will go out hard. Virtually no difference though.

um so anyway I just going to uh do some solar place place these by hand. It won't be efficient when I actually manufacture the couple of panels I've promised to manufacture for the kickstarter uh campaign I will have to set up like a semi production run I'll get like you know, the uh tapes of uh components and I'll stick them down to the bench here and I'll be able to go boop boop boop boop boop boop boop like that and sort of, you know, production. uh, assemble these cuz when when you're just doing one like this, you got to get the parts out. They're all in little individual Digi key packets or they're all on reels like this which is really annoying.

Then you got to extract one off and you know, so it's very U time inefficient to just do one, but that's what I'm going to do today. so don't take this as an efficient way, uh, to hand assemble a production board by any stretch of the imagination. So first thing I'll do is just cut it out of here I'll cut one out and because I don't want to do it in the panel of course. So oh, there's not one there.

There's one there. and there's another. oh look at that there. my there.

my um. exite. uh Cutters they're only about 10 bucks a pop. but I use these for sort of because they're cheap.

Um, they they work okay, there's nothing. WR the quality of these. uh, for those who are asking, um, quite a good uh pair of side. Cutters for 10 bucks.

Nice flush surface on them, but um, yeah, they are sort of semi-disposable So I use them for sort of cutting. Uh, the sides on here see. this is the reason why I don't uh, put these in the I Why I put these in the corner on my production panel because look, it just leaves an ugly mark on the side which you know if I was actually presenting selling that I'd have to sort of, you know, file that down and finish it off. but you put him in the put them in the corners and the Finish is H much nicer than that.

Anyway, here we go. there we go. I've got my board held in place there on my template and I've lined up my stencil and that looks quite nice ready to apply the paste taada and that looks quite okay. The uh, paste application down I mean the smallest Parts down in here 06 Three and six pin so 23s that's that really has worked.

A treat. I don't have any missing pads there at all. Awesome. Ready to place so I'll probably start with my uh Precision resistors here and these are little 06 03s as I said.

I uh, this will not be the most efficient way to do it I've just flipped them out there. Ordinarily, you know, if you want to do this properly, you would, uh tape the these down to your bench and you'd have a proper vacuum. you know, foot operated vacuum? uh, press like this or maybe some uh glue? Tac uh tacked onto your end to lift some larger components up into place and I'll uh, no doubt, show that in future videos. but uh, for now, I'm just being uh, incredibly inefficient and uh, just placing them one by one.

So R3 and uh, r13 for my 6 k8s. So I have have to be uh, actually, careful there not to uh, put my hand over that R6 and r13 where are we? There's r13 There we go. it's flip it around here. and uh, as I said in the previous video, you don't have to be really precise because the parts should uh Reflow back into position.

The surface tension of the uh of the paste actually pulls them in place. and by the way, don't sneeze when you're doing because your components can go everywhere. It's not pretty so 2k2. so I need two of those as well.

These are uh, 0.05% 10 PPM resistors They're not. Uh, they're not hugely expensive, but they're not cheap either. You know they're like 30, uh I think 35 cents or something in like, you know, a couple of thousand uh, quantity in a reel. So all R 11 R14 Here we go.

Hey, get in place there, you little turd. All right I Probably should have timed this. Um, but yeah, as I said, it's not really. it's not hugely efficient.

I do find 063 a bit annoying. Um, o 0402 would be a pain in the ass to hand place. Um, 0603 is getting a tad down in the annoying range that's for sure. So that's my uh 1K resistor I need two of those as well and well I don't know what else I can tell you folks, this is not going to make for interesting commentary.

that's for sure. Do I say this was a quick video. well you know it never is here on the evev blog. Uh, where are we sorry I'm not just I'm not going to show this up close I just you know.

really, it's not that exciting and R15 R5 where are we R5 There we go. You really do want to start with the uh, small parts first like that it's usually the best way to do it. Get all the pain over and done with first and then I've got a uh 10K Precision resistor I only need one of those and of course um I what I'm also going to do is go check the data sheets for some of these like for example: uh, is it on here Yeah, there we go. This is the uh, this is the opamp the Max uh, 42, uh, 39 and down here.

look there you go it. uh warning Will Robinson Max Safe Temperature 260 C that's why it's uh, it's more important to get you to ensure that your thermal oven doesn't go over the maximum temperature rather than you know, get the exact thermal profile. uh, right. especially like you know, critical Parts because even some data sheets I'm not sure if this one does, but you know, um, it does.

For say, voltage references. for example, they will have graphs of its performance before and after Reflow and you know and and you can see like the mean shift I Haven't got the graph here, but you can actually see the shift in um in in performance of the reference after Reflow at a certain temperature and they only characterize that well based on their recommended Reflow profile and stuff like that. but it can really, you know for precision Parts it can really have a difference. that's why I Want to check this cuz this has some expensive Precision Parts in here and uh, you know I want to make sure the performance is still there after I Put it through my Reflow oven and it's better to do it on one board than uh, you know, find out.

Oops, you know something's um, there's some little uh, Murphy thing that's going to get you uh, and you know, ruin your day and you don't want that to happen on a full panel of 10 boards. So there you go. What's this? 10K I'm back I'm too busy talking and I know for a fact that one goes down in there like that and uh, well, it's tempting just to whack in that, but I won't. So yep, on to the Uh so 23 parts.

Now these are my two maximum parts. Now the problem with these is that by eye I'm having a hard time seeing where the dot is I can just see it I think I can just see it if I get the right light on it I can just see the dot and I will try and transfer over to get the correct because the thing about the six pin so T 23s is that uh, they look the same like you know you can actually put them in uh, backwards. So oh, did I touch the solder paste there I hope not. let me get around there like that.

I was trying to reach right across the board. that's not very good I'll just go double check that that I have got that dot right under the microscope and yeah, I'm should have trusted my eyes I got that correct I was you know, just avoiding Murphy there and always double check your work because really, that's the point where they're really, going to screw you. You always get screwed if you don't check assumptions, never assume anything in electronics as the diode because it will lead to a great deal of hurt. I can assure you an embarrassment if you're you know, working on a critical project or something like that.

And yeah, now here's a Uh I have to extract this from a reel and I can be really annoying. Just be careful not to apply too much pressure on here and they all go flying. This is one of the leftover reels from a previous production run because um I you know I'm using most of the same Parts um well I lot of the same parts. so this is the uh, this is the Uh Supply Monitor and uh yeah I Usually you don't order the exact number of parts.

I mean um, you know we you talking about passes or ones like this. If I'm doing a production run of 500, I might um, order one of these Digi reels here I I did Uh 250 I ordered Uh 250 here I was probably doing a production run of 200 and I ordered 50 extra. That's probably more than what I needed at the time, but you do need some uh buffer there because you the uh assemblers will ultimately lose some and uh, they generally don't want to deal with that I mean you can they? They can capture them. the ones that fall off, you know they either fall off the head of the machine or just you know handling and loose tapes at the end and stuff like that.

So um yeah, you know they can. You know, if worth you know, 10 bucks apart then it's going to be worth their time for example, to actually collect those and reuse them. But for something like this that only costs you know 10 or 20 cents each? they they just it's not worth their time to go and collect them. and certainly not for the uh, passive? uh Parts You know that are worth .01 cents each for your passive resistors and your caps.

You know if you need uh to make 1,000 boards then you wouldn't order a reel of a th000 you know you'd you'd need like you know, 1,200 on the you know, 1100 or usually I think um you know assemblers have their different uh uh recommendations for that but usually it might be say 5% over or something like that for your passive part. So just be aware of that when you're getting these things assembled and when your manufacturer comes back to you. If you haven't done it before and please make 1,000 boards, here's a real of 1,000 parts and well they come back to you and say sorry I couldn't manufacture 1,000 boards because you didn't give me enough Parts what? and uh yep or they charge you more for it or they don't tell you and they simply charge you more for it. That's more annoying cuz then you never learn that you never learn what what they want and what they're actually charging you for.

So jeez, this board is taking a lot longer than it normally would because I'm too busy yapping. But there we go. Got a couple of more parts. Not a big deal should be done, you know? I can I You know my guesstimate would be for hand placing a panel of 10 of these.

I'm You know my first gut feel of the guess of that would be you know, like ah, I don't know a couple of minutes per board if I can't assemble one of these one a whole panel in an hour? Uh, when I've got everything set up and nicely and I'm just transferring things over, then you know I'm probably not doing it right. And here for example is a reel of a th uh of my um 10 ohm Precision resistors there a 0.05% 10 PPM Um, and they're not that, uh well, they. they're not hugely expensive, but I did have to order a thousand of these when I you know, sort of when I committed myself to doing this project. This is even much long way before the uh, way before the kickstarter campaign because you I couldn't get these in stock.

um, anywhere in the world. Pretty much they are now, which is kind of annoying, but back then I made the commitment and I had to order a. you know I knew I was going ahead with this eventually. So I ordered a reel of a th000 Parts even though you know I had no idea how many I was going to make I probably only going to make a couple of hundred or something like that, but I really had uh, really had no choice in that at the time and uh, that's the es and flows of the component procurement process.

One week There's Parts there and well the next week There's not and you're on a you know, a two-month lead time. It really sucks And on goes my most expensive part, which is, uh, my. Precision .1% um current shunt 10 10 milliohm current shunt and uh, these are you know, four five bucks a pop in thousand of volume? they're not. They're not that cheap.

There we go. Plunk down, it goes. Oh yeah, there was, uh I was a concern. there was a little bit of uh paste not on on that pad.

It wasn't fully covered, but that will uh Reflow Just fine. I've only got a couple of bypass caps and some uh Jelly Bean 2 70 ohm resistors left. there you go I got all my parts in place. Yes, there's two missing caps on there.

that is deliberate. don't worry about that. and uh I think yeah, we're ready to Reflow that that battery holders around the correct way. Yep, let's go to the Reflow oven.

Now the issue I had when I first played around with this uh, thermal oven is that some of the parts on this board. uh didn't Reflow like these three resistors down there. It was because they were over one of these metal bars in here and that was causing a you know a a a sort of a cold spot along that particular bar because it has thermal mass and yeah, a whole bunch of uh people said yeah, we've encountered the same problem and you shouldn't put your board directly on top of the grill like this. You should have a nice even metal uh plate like a grill on there I don't actually have that to hand right open and well, it's Boxing day and everything's closed so it's not like I can just go to the hardware store and pick it up.

So I will, uh, make do just with a single-sided copper clad board like this I Have no idea if it's going to work well, probably shouldn't use um, a copper clad board like this for you know, like a permanent uh, basis because it's you know it's not designed to be deliberately heated up and then cooled down and heated up and thermally cycled like that, but for the purposes of today's experiment, it might help to more evenly uh, you know, distribute the heat over the board. so instead of having the copper directly contact in the bottom of the board, don't want to do that. We'll put the copper side down. We'll whack it in the center like that.

Oh, fell right through, whack it in the center and there's our control PCB sitting in there. I'll I'll tape that down properly so it's making, uh, better contact. and then we'll put our board in there like that. There we go.

and uh, almost right to go. Actually, before I do that, I'll just put my control board in there. I've taken out my microcurrent board and I'll just use my uh Reflow uh controller over here and I'll do a learn mode on that. So there we go.

All right. So that'll just, uh, heat up to 100. uh C And then as I explained in the previous video, we'll get the over ramp on that. Uh, because you know when you change your thermal characteristics inside the oven which we have done with that copper clad board, then really, you know you should run that learn process.

Okay, the oven is cooled down and my board microcurrent board is going in and I'm going to log that on this. So uh, got that connected to my agilant meter there and here we go. All right we are soldering and uh, should take uh I think uh from last time, it was like 5 minutes to uh, ramp up or something like that. finish the profile and start ramping back down and we'll be able to follow that on the uh thermal profile here.

Well, we'll be able to see it at the end anyway. If I go in there and select uh, show all then oh there we go. You can see it started to ramp up. that was, uh, part of the uh cooling there from the um learn mode I did but you can see it has started to ramp up and uh, well, it'll take a while.

We'll come back when it's toasted and I'd love to get a real good uh closeup of this thing. uh, reflowing for you but unfortunately it is in the center of this and I got to shoot through a glass door and it's dark in there and well, you know I can't get my macro lens cuz it can't shoot at that distance etc etc. so this is probably the best shot I can get of it and well yeah, sorry, it's not that great and the controller is just switched into the Reflow phase so it should. The heater is full on now so it should ramp up reasonably quickly now and it should start to Reflow you know around about that 220 C Mark it's about 178 and climbing at the moment.

There we go, we've hit 220 and I think I can some of that uh paste reflowing probably has. It's hard to tell though. I'm just staring at the screen of the Uh camcorder at the moment. and then we're into our short dwell cycle.

So it's switching the Uh element off and on again. and that noise that buzzer means we're done. We're all done and dusted. I Have to open the door.

There got up to a maximum of about 231 on there and we'll have a look at the thermal profile in a minute. but I need this to ramp down faster than what it does when the Uh door is closed cuz this Uh retains quite a bit of heat. So hopefully our board has reflowed. That's the plan anyway.

and that looks like it has reflowed quite nicely. I Like the look of that. No problem whatsoever. Even the big Um, you know, the larger thermal Mass uh battery holder there looks like it is reflowed on the edges.

It's hard to see because the pad of that is not much bigger than the Uh than the tab itself. So that's the recommended Uh footprint and the Uh reverse lead there. Let's check out our main current shunt resistor down there. That looks really nice.

Not a problem. that folks is a winner. And there's our thermal profile. and if we get in there, we can actually see the top temperature just over 230.

see there. I Like 232 by the looks of it. Um, and that precisely matches what I saw on my agilant meter as well. That's the maximum value I Got out of this thing.

so I've got really good confidence that I'm not going over temperature with anything on this board. so I'm really done happy with that. and it really shouldn't matter how many of the boards I put inside there either. Um, you know, because it it really doesn't.

uh, change the equation at all. Check it out, that looks pretty Jazzy with that Olive uh Type green color I Really like that and uh yes, the light comes on. Woohoo! Fantastic! Do a couple of quick checks and uh, see what it's like and that appears to be well with inside the 05% spec of this thing. In fact, it's you know, calculates out as 0 76% So it's basically um with inside the capabilities of the instruments which I've got here.

I um am capable of doing more precise measurements but it in in the lab here but it requires you know, setting things up and it's just a little bit awkward. This is, uh, just a basic check and yeah it's it looks good. Beauty and if I get out my HP 345 78 well it's even closer. Um, it should be you know, 44 or actually you know, according to my uh Agilant meter that's measuring the current and well, you know we're bsing it in.