The quest for the right connector for a project! The right of passage for any hardware electrical engineer starts with a connector catalog.
This is the last installment of Stephen's 'Adventures in Injection Molding'. We are going to recap the entire two year sage and close the book on it.
The Jeep Prop Fan project rides again! Well some iteration of it at least. Lets design an open source PCM (Power Control Module) for automotive apps!
Parker is an Electrical Engineer with backgrounds in Embedded System Design and Digital Signal Processing. He got his start in 2005 by hacking Nintendo consoles into portable gaming units. The following year he designed and produced an Atari 2600 video mod to allow the Atari to display a crisp, RF fuzz free picture on newer TVs. Over a thousand Atari video mods where produced by Parker from 2006 to 2011 and the mod is still made by other enthusiasts in the Atari community.
In 2006, Parker enrolled at The University of Texas at Austin as a Petroleum Engineer. After realizing electronics was his passion he switched majors in 2007 to Electrical and Computer Engineering. Following his previous background in making the Atari 2600 video mod, Parker decided to take more board layout classes and circuit design classes. Other areas of study include robotics, microcontroller theory and design, FPGA development with VHDL and Verilog, and image and signal processing with DSPs. In 2010, Parker won a Ti sponsored Launchpad programming and design contest that was held by the IEEE CS chapter at the University. Parker graduated with a BS in Electrical and Computer Engineering in the Spring of 2012.
In the Summer of 2012, Parker was hired on as an Electrical Engineer at Dynamic Perception to design and prototype new electronic products. Here, Parker learned about full product development cycles and honed his board layout skills. Seeing the difficulties in managing operations and FCC/CE compliance testing, Parker thought there had to be a better way for small electronic companies to get their product out in customer's hands.
Parker also runs the blog, longhornengineer.com, where he posts his personal projects, technical guides, and appnotes about board layout design and components.
Stephen Kraig began his electronics career by building musical oriented circuits in 2003. Stephen is an avid guitar player and, in his down time, manufactures audio electronics including guitar amplifiers, pedals, and pro audio gear. Stephen graduated with a BS in Electrical Engineering from Texas A&M University.
Special thanks to whixr over at Tymkrs for the intro and outro!
Welcome to the Mac fab. You look so confused. Steven.
I'm just waiting for you to intro.
Okay. Welcome to the Mac fab engineering podcast. We're your hosts, Parker, Dolman. And Steven Craig, this is episode 268. We gotta get good at that sometime, right? So I'm been working on my Jeep a lot, you know,
go figure, right? It's always on, it's always got parts falling off of it and going back onto it,
you purposefully make parts fall off of it. Yes, that's
true. It doesn't actually it doesn't come apart on its own yet. So I've been I've been working with a brushless fan temperature controller that's on it, I'm not developing it or anything like that. It sounds like you can just buy it, I think it's called delta Pag. P AG. So if you Google that it's like a brushless fan setup. They're really nice. They're like one of the most powerful fans on the market. For automotive stuff. What is funky though, is the controller that you get with it, it's really nice setup where like, you can control two fans with it. It has a temperature probe built in, and it's got little screens, so you can adjust the temperature cut offs, all that good stuff. But it's weird on how it functions in terms of like it's override signals that you can give it because usually what you want is when your let's say your air conditioner in your car turns on. When that turns on, you want to run your fans. So you're cooling down the the condenser on your car to cool that the gas down or I guess at that point, the liquid, the, the cooled liquid down at they're compressing it. And so most temperature controllers for cars, they are they basically read that clip the what's called the clutch on your compressor. So your your belt is spinning. And when the clutch engages, it engages the compressor to the to the pulley. And that's a high voltage signal so or high voltage troubles. But what's interesting is this controller doesn't use the typical high voltage like or a high signal, the activate the override, it's an active low. It doesn't make any sense. Because the only time I've seen that if we're a controller, and like I sent them an email about it, I'm like, Hey, is there like a way to like flip this around. Because basically, like you're forcing everyone to like, you basically have to build logic to flip a 12 volt signal into an active ground signal instead, they never responded. So like, I'm basically just gonna take a relay and just do an inverse function with the relay, which is kind of annoying that I had to do that. But you know, it is what it is. But the other weird thing about it is most controllers will tell you what the temperature center is. So you can like replace it with something that fits better. Like you know, if you have a different if you have a different NPT, you know, nice national pipe thread tap size, you can use the right size center fort.
Educate me real quick. I'm not what is a sender?
Like the temperature sensor? Or what they said sender? Not yet sender. So, in automotive terms, sensors aren't sensors. They're senders Oh, God, really? Yeah. So some people come sensor, you can call them both. But the automotive world is really a sender because it's more of a it's sending a signal. Yeah, it's a more old school term. An automotive?
Yeah. Like, my father contacted me the other day and he was working on one of his motorcycles. And it was kind of cute because he was describing one of the circuits and he's like, it has this thing called a condenser and eighth like you would probably call this a capacitor and I'm like, Thanks, dad. I know what
probably a similar idea there. So send her sensor. Those are the same things. Okay,
so next time I go to get my car fixed that can flex a little bit.
They might think you're weird too. Yeah, they probably think it is a more old school term. So newer cars, they just call them sensors. And sender is more like an oil sender oil pressure sender. I don't know if this sensor was anyways regardless, you usually tell you what, what kind it is. So you can get a different kind, like a different physical shape for it. This one also doesn't I asked them what it was because I needed a different physical package dimension for the sensor. And they didn't respond back either. So I guess it's like, it's amazing products that the customer service so far is junk. So why did like any engineer would do is I just profiled the, the sensor, you know, hot water and a little temperature probe. And it's a it's a typical NTC you know, 10k the rooster doesn't do fancy, I just bought another one that would fit and I plugged it in, it worked great.
They can't protect against you doing that. That's that's one of the funny things about backdooring stuff as an engineer like, yeah, you can like they'll have these like really special things where it's like, you have to buy ours, it's like, oh, I think I can figure it out.
And so and so the reason why I went with theirs is because it those the brushless stands, you can PWM the pin. So you can speed control it, which is actually really nice when like you can so you can speak control. So it's like, okay, it's starting to come up to tamp. So don't blast, you know, 3000 CFM of air through it just do a little bit until like it heats up more than ramped the fan up. So like all that stuff works great. But and so I got their controller, I'm probably going to take my oscilloscope and then probe that PWM line so I can get what it's what its duty cycle and frequency is. And just, I'm actually almost think about rolling my own controller, just so I don't have to put a relay in here to flip that signal. The AC compressor signal.
So wait, so this thing has PWM control, but also an override pin.
Yeah, the override is so that if like, okay, the ACS on compressors on and generate heat. So go ahead and run the fan. Yeah. But then you could do crazy funky stuff like you can, if you actually made your own controller, you could do like, interesting profiles, like okay, the engines just started up. And so it's engines cold. But you're running the air conditioner, so maybe not run the fan 100% then run it you don't need 100% That CFM just to cool the condenser down.
You can make all kinds of profiles and curves based off of the logic of what is happening based on time or what's actually running at the moment.
Yeah. Well, I do that. I don't know. Well, you are making a controller right? For different stuff, though. Okay, so this isn't? Yeah, this is just gonna be its own standalone thing. So I didn't actually have to design something. Now I'm probably gonna end up having to design something. So just so I can get away
from it. Right? You like you're actually going to be able to adjust things from your dash
with the temperature controller for the fan? Yeah, no, it's mounted under the hood. Okay, so this is like a set and forget it thing. Yeah. You said, when you first set up your your temperatures, and that's it.
Okay, I thought when when you were suggesting that it had a screen, it's something that you could optimize the performance of your
bed? No, no, no, no. Well, I guess technically, you can mount it in your cab if you want it. But you know, I'm just like, Yeah, I'm gonna set it to, like, turn on it like, you know, 200 Fahrenheit and turn off when it's like 195. Like, some standard, like what normal cars do?
Is there? Is there like a, like a written standard for that?
Not really, it's usually in that range, though. Because what you want to do is you want to span you want the fan to cycle. So you just kind of set it up to cycle.
Yeah, but in Houston, like there's no cycling, right? It's
It depends. Yeah, if you're if you're 100 degrees outside, and you're stuck in traffic with the AC on max, it's pretty much we're gonna be on all the time. Yeah, but that's just normal. Depends on what your normal is. Right. But
they are continuous duty cycle, right? They can't
Yeah, it's continuous duty cycle.
I guess just efficiency is the reason why you would want it to be
controllable. Yes, yeah. So yeah, maybe I should open up that, like crack that box open. Because this is the thing is like, if it's outside the unit outside, if I make that invert inverter circuits, it's like I had to pull it on the outside and then I had to give it 12 volts right for the relay to flip correctly and what's up, but what if I just cracked open the box? And then I then that I could solder? A logic level inverter in there.
Yeah, I you know, I was going to ask earlier like, why a relay and again it because it's external to the box. Yeah, but yeah, I bet you you could very easily just put a transistor that just flew Have things around in there? Yeah. Giving yourself a broad check. It's a box that you purchased that wasn't a project that turned into a project that turned into a deeper project. Yeah,
it's like I'm like, I'm, like, going back couple episodes where I was talking about, like the multi gauges for sensors or senders and cars and stuff. And I can't find anything that just like, I actually try, like probably like once a week, before I even start working on it. And like, there has to be something out there that's like, I can just use like something on Etsy that someone's designed or open source thing. I can just get built. It's like no one has anything that's like that. That's just like, I want like an Arduino shield. I plug on and just I do the code part.
I'm kind of thinking of like automotive parts on Etsy. And they, they have they have like a nice floral print on them. And they say live laugh love on this side.
Now this is a quite a bit of electronics on Etsy.
So is that really I don't forget.
Oh, no, I'm thinking of 10 D.
Okay. Yeah, I was like, it's he doesn't seem very electronic.
No, you're right. You're right. I was thinking of tindy Yes.
Cindy has a lot of you know, maybe we should start the first or whatever. The the most in depth official electronics place on the on Etsy. You could sell pinball controllers on Etsy
and crafted and built
your the controller world, aren't you? You do a lot of controllers.
I do a lot of controls. Yeah. At least hardware controls. I don't do a lot of the firmware though. But the fan controllers, definitely. You know, I actually should open it up anyways, and just see what kind of microcontrollers in there too.
I mean, okay, a box like that has to have a controller of some sort, some kind of microcontroller for sure. But a controller, it has some way to read back the temperature. So it has some kind of what you said it was an NTC,
right? Yeah, it's empty. So it's probably got a resistor bridge in there. And that's it,
right? And then and then it has some kind of driver output for the fans. Yep. And some power conditioning.
And then it hooks up to a looks like a custom, like LED screen. Like it's like a segmented screen, but it's not a it's not a stock one that I've ever seen.
Why does it have a screen? If you mounted under your dash? Is it just so that you can select
things? Or yeah, so you can select what temperature it turns off and on. And then then I basically after you set it, the screen just turns off, it goes into the screen goes to sleep mode.
Interesting. That seems like I mean, that's something that you will set and then you'll never set it again. Right?
Most Oh, that's you repurpose it? But yes, yeah, yeah. Oh,
this thing has multiple uses.
Well, you can It's this. It's more. This product is more for like race car application. Then Jeep application. Oh, so this is a fine tuning tweaker box? Yeah, yeah, it's for tweaking and stuff like that. But I'm like, I'm probably going to set it to like, well, I fired all up and apart, take a couple days to set it to get to temperatures, just right for the fan and and then be like, Okay, I'm done.
See, what was going through my mind is because of course I think about it in terms of manufacturers, like would it be cheaper to instead just have a small USB port on the side, and a computer application that allows you to select five different profiles or something like that. And that saves the cost of having to write firmware for a screen and having to source the screen for for what ends up being very low usage part, you know,
yeah, I actually do agree with that is it's also displays the temperature, like if you press the button, it will display temperature, which would be really useful trying to figure out like when it's turning on and turn it off that so you could set it without this is also the thing with the automotive industry or hobbyists I should say, is a lot of them are very adverse to computers, or computer controlled anything. So even a fan controller, it is having computer control it is computer in there at the barrow sense yeah, but it's just one of those. Now you're asking someone to go get their a computer to poke up into their hot rod, right and they drag out a whole tower and everything. Yeah, it's just it's weird. So I do understand why they don't do it. Why a lot of customer companies don't do it, but like my digital dash Have for my wagoneer I would love to have that. Like, if I can just plug a USB and then do all the settings like oh my computer like, be amazing. But no, they, they went through all the effort to have Bluetooth for it. So you could Bluetooth connect your an app on your phone. And just like oh, Mike, come on, just give me a USB connection. So this, yeah,
I was about to say if this was a hacker maker, that little box would be Wi Fi connected. So you would have to be near your house and then connect to your network. ESP
a 256. Something in there, right? Yeah, it's just one of those mentalities kind of like, for me, at least it's like, wired. You think like someone my age would be like, oh, yeah, Bluetooth, blah, blah, blah, blah. It's awesome. It's like, No, I just want like, it's the engineer in me. That's like, no, just give me a wired connection. Like, give me a give me a 96k serial port. Yeah,
you can. Yeah, you can really get under the hood with that.
But yeah, I should pop open that that controller box and see what's actually in there. And because that would actually be it. If it's it, see and see how easy would be to invert that signal? If it's,
what's the voltage levels on that signal?
Is it 12 volts? Zero? Yeah. Yeah, trouble too high, then. Zero is? Zero volts. Well,
I mean, okay, so here's the thing, if, if, if it's 12 and zero, then whatever controller they have in there already has logic, or already has level transition to get it up to zero or just a resistor divider? Yeah, potentially. Yeah. But But I mean, that's even works in your favor, because then then there's pads for you to install something on,
install something on it. Yep. So it's one of those. Put an inverter in there. And if I if you've feeling really, if it's, if it's something that I have a programmer for, that might be like one of those, okay, let's, let's go in here in and write our own firmware now. Yeah, cuz then you can do the profile part.
Now you're okay. I was I was, that's actually easier though. your hardware, your projects, just spiral downward. Rewriting firmware for somebody else's product that you have no clue about? I love that.
That's, though. This is interesting about that, though, is it? That might sound harder. But I could probably if I if I had the programmer for what, let's say it was a pic in there. Or embedded, let's say is the AVR 328. P Atmel. Chip. Those are the same thing now. Right?
Sir, daily reminder that microchip bought at Mill.
Yeah, that was what, like a year and a half or two years ago. Two years longer than that, was it? Yeah. I, you know, I'll get a friend of mine the other day, made a whole argument that what was it? She was saying something she was having a chat with somebody. And she said something ridiculously like it was like goofy and kind of stupid. But it was, like, perfect for this podcast. Yeah, exactly. It was it was one of those situations where she said something where it's like, I don't people good or something like that. And she was just like, I'm sorry. I haven't seen people for like eight months in COVID. And I feel like that's now an excuse that's valid, like across the board where it's just like, I don't remember how long ago that happened. Because COVID just destroyed my concept of time.
It has it started a whole year ago. Like last
week. Yeah, yeah, yeah. Last week. My company was like, everyone go home. And yeah, I don't I there's there's people, my company that I've only seen virtually. And I'm a small company.
Yeah, well, same thing at McAfee. There's some there's actually some new employees. I only seem through a computer screen. Just kind of weird to think about that way.
Yeah, I actually did some training last week for just some general soldering stuff. And I've realized that all the
people feel sorry. Again, for
all the people that we did training on I was in their interviews, and I think maybe like two or three of them I've actually like been face to face with
I'm definitely cracking open that controller, like tonight or tomorrow. See what's in there. See what makes it tick.
Well, so what do you what are you hoping on being in there? Are 28 P. So it's easy for you to pay
any any controller that I have a software a, what's the right word? tool set already installed on my computer? Like what is my I'm looking at this, like what is the easiest path to make that signal? Not? ground reference or ground active, I guess. Which is why did they do it that way? If I would have known that before I bought it, I would not have bought it. Oh, really? I would have bought the fan. The fans great. I would have bought a different controller for it.
Yeah, I mean, the question is, are there other alternatives that like, suit your needs.
So the digital dash on the wagon controls its fan. And I bought the same fan basically for for the wagon, so that it worked great. And that's why I went with the same phenomena, oh, they have a, my jeep doesn't have a digital dash, it has all the stock stuff. So I was like, Okay, I'm just going to use their controller. And it's got this weird 12 volt, or it's a ground active for the override. And I'm like, This is so weird, whatever, I'll figure it out. But it's like I'd rather spend a day a day like a Saturday writing code than cobbling together a inverter with a relay. Just because it's like I don't want that really been under the hood. Just like it whenever open the hood, I always look at that relay and be like, I don't like you. Your entire job is to invert a signal and you're like, size of strawberry Okay, moving on.
Hang on. I got something for you. Give me just give me a quick second. Okay, because this whole chat has got me just got me going. This will probably end up in the in the Slack channel. Important. This is super critical. This is what we do on the Netfabb engineering podcast. We we make things while we're while we're chatting.
You making a meme?
Maybe? Yeah, I think I am. So it's check his left hand.
Do that's basically it. Yeah, yep. Yep. Yeah, that'd be I would definitely use that for for one of the tweets for this podcast. Oh, so he made one of those big brain memes. Yeah, they call them expanding brain mean? Yeah, it starts out as use the product as is and ends up as write your own custom firmware for a product. You don't know anything about the design.
Like you're talking about writing firmware, and you haven't even seen anything on the inside. You know?
It could be all analog and witchcraft. All I know. Yeah. You know, there's no way given how many how much functionality it has and how cheap it is, right? Oh, that controller was not not cheap. Ah, well, problem is I don't remember how much it costs because car stuff and I just, I don't really want to know.
Just don't show me my bank account. Just just auto pay.
Yeah, auto pay. Just warn me if funds go low. Yeah. So I actually did search fan controller on Amazon just to see what if there's anything out there. And most of its like PC related stuff. This is crazy. Okay, I built Steven I build our own PCs and build PCs for other people. There are some like but we build like normal people PCs.
For Yeah, they're based on function.
Yeah, these everything that's popping up is like RGB, like bananas RGB This isn't crazy stuff. I remember when I was a when I was in high school I built my own computer like case and was to kind of like into that whole like custom building computer cases and stuff. The mouth like we had to like okay, this sounds like walking up the snow both ways going to school kind of thing. But like we build our own RGB fans, like by drilling holes and fans and like hot gluing LEDs and stuff and tell them
what you did back in the day. Yeah. Oh, wow. Okay,
but I'm like looking at this and like, oh, I can buy like, like, crazy 120 millimeter case fans that have magic Moon series, high performance cooling PC fans that have like applications that run On your computer, so you can change the colors of the fans for like 20 bucks.
I don't honestly I don't really get the whole PC master race, like craziness with especially with the RGB thing I saw, I saw a video card the other day that the side profile of video video card had an LCD display on it such that if you had a clear side case, you could have like gifts and stuff running on the side of your video card.
So that's cool. Okay, so, okay, it's not cool for us because we just like my computer is like a beastly gaming computer. And it's like in a four year rack mounts. Right that sits on the floor. Yeah. Now if you have that little screen on your keyboard. Well, they do say that they have they have plenty. Yeah, they had a Logitech. Logitech had a keyboard like that back in the day. But yeah, that would be kind of cool.
It ends up it ends up looking similar to DEF CON badges. When when you start caring Yeah, kind of stuff. You know? Yeah. Like just goofy LEDs and Futurama gifts running around. Okay, let's, let's move on. Let's let's talk about maybe something perhaps a little bit more serious. Here.
So this podcast? Yeah, no, sorry, I
lied. So no, no, I, for the past couple of weeks, we've talked about some some interesting stuff about design. And I thought it'd be fun to have a quick chat about controlling your PCB cost. And what I mean by that are like, what are the knobs that you as the designer have, either the knobs that you know, about, or maybe the knobs that you don't know about that you can turn that adjust the cost of your PCB, because in a lot of ways, when you first start getting into PCB land, you just start trying things, and then you realize, oh, shit, this is expensive. And there's a lot of those pitfalls. So I thought Parker and I could just kind of gig a little bit on a handful of things that just, if you do this, there's a likelihood that costs will go up. Or if you do, that likelihood will go down. So I have a list of what I call the easy ones. And if you go to most of your your big PCB, website, PCB manufacturer websites, they have like online quoting tools that you can go and you can sort of just adjust these things that I'm talking about these easy ones, and see for yourself, what's changing. But there's nuance behind each one of these. Because you can't, those online coding tools are only as good as they can be. Because you can you can sort of game the system and and get something that that the online tool be like, yeah, sure, this is X dollars, and then they, the designers look at it, and they crap themselves. So it's something to keep in mind, because you don't want to design something wacko into your system, that ends up costing a bunch of money. But you, you assume that it was acceptable, because the online tool said it's fine, you know, and that applies across the board with with pretty much everyone. So sort of the first one, and it's probably one of the more easy ones to consider is just the size of your board. In general, as your board gets bigger, things get more expensive. But that's not necessarily always true. Especially because it's really, really highly attached to quantity. So if you have one board, that's really big, it that's probably going to cost you a bunch of money. That's in general how it's going to be. But if if you're talking about 1000s, and 1000s of boards, and they're still big, then it kind of gets all the all the overall cost gets spread out among those boards. And so the overall cost per board is not going to grow linearly, for sure. And in the size category, something to keep in mind is you might have an idea for, I don't know, a single PCB that goes on the inside of a baseball bat, and it's half an inch by 24 inches long. That is a great example of a situation where Yeah, sure, maybe just maybe an online quoting tool would give you a cost for that. But that's a really odd shape. Something where you you talk about extremes in any direction, you're going to start to see either somebody tells you no or the cost will skyrocket because you have something kind of goofy
and and the thing about this size is sure you might be able to get PCBs made in that size, but you're talking about that extreme, especially like let's say you had an inch by 24 inches. The problem with that that size is you start running into assembly problem Seems like a machine that can fit a board that big. Because I know that there's definitely some machines out there that can only fit like a 12 by 12 panel.
Yeah, and actually what this, what a lot of this boils down to is. So Parker and I say DFM a lot designed for manufacturing. And that's a little bit of a catch all term. And in a lot of ways, when you're in the middle of your design, I almost feel like there is a different term called DFC, which is designed for capability, as opposed to just designed for manufacturing. are you designing such that someone is actually capable of building your thing? Because if you think about it, if let's just say you had an infinite pot of money, DFM doesn't matter, right? Like, I mean, you could you could have someone build anything if you just had enough money. But are there the right tools? Are there the right machines? Are there the right capabilities to get your product made? That's why it's always worth kind of designing around constraints that work with your manufacturer, we say it all the time. Contact, you know, once you pick your beloved manufacturer, contact them and find out if their name is macro fab. Yeah. 100%. Guaranteed every time. Yeah, so So find out what their capability is, and then start designing around that. And I can tell you right now, Max, Feb would not be really happy. If you ask them for a one inch by 24 inch board. They it's not that they wouldn't be happy to just be like, Yeah, we really can't do this. And maybe we can work with you to adjust your design,
I think the biggest board the platform of like,
isn't it? 300 millimeters by 300? millimeters?
Yeah, I think the biggest board you can upload is like a 17 by 17. I think it's what the platform says, Let me check real quick. But you can contact us at at support at macro fab.com? Because I definitely know I've seen a four inch by 36 inch board, which is in that extreme range. I don't think it's for for baseball bat though. With 36 inches long. Yeah, we built it
by hand. Like did it go to the pick and place machine multiple times?
I don't know, actually. But yeah, it did go through the pick and place
well, okay, so maybe I stand slightly corrected there. As in, if you have something that super uber extreme like that somebody can make it. But just know that you're probably going to spend a bunch of
Well, yeah, that's the thing is our auto quoting tool can only handle up to like, I just looked at like 14.9 by 14.9 inch. Okay, so that's over 300 million. But so it's bigger than that, but we can still quote it and manufacture it, we just can't automatically quote it because it's such an outside the bounds of like the normal, like 90% of what PCBs assembly is,
you know that okay, so that's actually a good point right there. If, if your design can be quoted on an online quoting tool, which I would think that a large portion of designs can be, then you can expect that if you go to macro fab, or if you go to someone else, it's probably going to go through pretty smoothly, if it can't be. But in a lot of ways, if you don't fit the criteria of those online quoting tools, you already know that you're not going to, I suppose what Parkinson talking about here is how to avoid like walking into a pitfall where you don't know that you're going to need that special quoting. So okay, so back to the easy ones. We talked about size. If your design feels ridiculous, it's probably ridiculous, like four inches by 36 inches, there's there's got to be a really specific use case for that. Why couldn't it be smaller boards that are smaller that have connectors and cables in between them? There was some use case where a four by 36 made sense. So they another thing is penalisation which that's something that you would work with your contract manufacturer with or perhaps they would even just do it for you controlling the cost of your PCB, can it be panelized up into an array, such that you can distribute the assembly cost across them, if you demand that your board gets assembled one by one, every single board one by one and you need 10,000 boards, that's going to cost a lot more than if you can array it up in 100x array and then the machine runs it as one big group.
Now the one want to say on this is back to your your when you first brought it up is let your CMP analyze it. There'll be a lot happier because your CSM is going to know what's the best way to penalize it that's going to fit in their process and what's going to be the best price for their PCB fabricators and terms of their fabricators panel sizes because they, they have a big chunk of Fr for right. And they're rounding out your boards out of that. And so they have some standard panel size that they're working with. So they're the CM should be basically optimizing the their panel to fit that bigger panel. So you they get less waste, wastage.
Right? Right. So yeah, like, once your board is done, as in like, the end result of what you're expecting in your design, you don't necessarily need to go through the exercise of adding PCB rails to your board, or at or analyzing everything. I've seen that a handful of times where somebody tries to micromanage the entire process of everything, and then the CM get forced into building something that is potentially suboptimal for their process. Because they were just, I don't want to use the word demanded by the customer, but but it's just, there's no wiggle room there to ask them.
So what I tell our customers is, the customers that I deal with that will give me something that's pre panelized, I'm like, you're gonna get it panelized. We're not going to break it up, you ordered your board like that. So you're going to
get it like that, yeah, you have to break it apart. And then they
go, Okay, here's the one up.
And I think that there's conflicting data on that or not data, but there's, like, if you go online, there's lots of tutorials on like, here's how you penalize things. So you can send it to your manufacturer. And that's great and all but and I say great knowledge in terms of perhaps you work in an industry where you can't give the original files to your, the original design, fire issue, contract manufacturer, or you, you don't want your gerber files to be modified in any way, perhaps you're restricted on that, that's fine in that situation, work with your CRM, such that what you are penalizing is what they want, or what they can do. But if you haven't even talked to your CRM at all, and you send them penalized files, like you're a few steps down the road, that you should be thinking maybe a little bit earlier in the game.
Next, sometimes the CME if that's your case, the CME will give you like, Hey, this is our specifications for our panels, like macro has got a lot of different ones, like maximum number of parts that can go on a panel, which so that mean, that's like the big thing that takes you know how many boards you can put on. Like, if you have a really high density small board, you only going to be able to put like 20 of those on a panel, you can't put 100 Even though 100 could probably fit onto a 12 inch by 12 inch panel, you run into that part limitation number. And that's just for like, safety factor on like, throughput through your pick and place machine.
Well, yeah, if you think about that, too. Not only just throughput, but let's say, I don't know, let's say each board is $1,000 worth of parts. If you got $20,000 on your hypothetical array, and something goes wrong. Yeah, you're out. $20,000. But what if, what if something goes wrong and a whole 100 array is destroyed on $1,000 worth of parts per? For things? Like it stacks up real fast? You know? Yeah. That's a little extreme, though. It's usually not a little bit. Were the even even talking about extremes for everything. So yeah, pretty much. Yeah. So avoid the extremes, that's usually you'll, you'll be good, right? So next thing to consider is your base material, that what your board is actually made of. So generally, you know, you're talking about fr for, I don't even necessarily want to talk about the other materials, because it's one of those situations where if you know the material, then you know, you need it almost in a way. But but the T G rating, that's something you'll see on those online calculators. So the TG rating is the glass transition temperature, it's basically how much heat the board can handle. And it goes from some low number to some high number and the cost increases along with that. So the question is, do you just arbitrarily want to pick the high number? Because it's high number equal? Good, right? It depends on a lot of factors. And it depends on what the board is going into. If it's just like an IoT device on the wall that just sits in someone's house. You don't necessarily need a high DG rating.
It's mostly how I pitches the people is it's what your what processes your board has to go through to be manufactured,
correct? Yeah, if your board I ever really needs rework on it or if it's ever going to be touched again, or if it needs handwork on it, or if it's going to go through multiple machines that are very hot, then you probably need a slightly higher TG rating.
And a lot of times, you can figure this out by looking at your design. If you have double sided assembly, you're gonna need a higher TG rating. If it's lead free gonna need a higher TG rating. A big one is that always, the biggest one is PGAS. If you have a beat, especially a large array, like 100, pin BGA, you're going to want one of the high you want a higher TG rating, because the whole thing with the TG rating is, is a higher T G rated board is going to flex less under heat, because it's going to be more rigid under temperature, it's going to be it's gonna get less soft in the reflow, so to speak. And that's the biggest. One of the biggest hurdles, I guess in BGA. Assembly is you got to keep everything coplanar. The moment it's something slightly gets off, you're going to have one side of the BGA will collapse. So we talked about that. So what T G ratings, y'all normally you're on,
we normally do somewhere in the range of 140 150.
Okay, which is you can see a lot of those online calculators, they start out at like 130, or even less or less. And if especially if you're doing lead free, everyone out there, do not pick those, because even during one pass that lead free temps pads will pop off your board. But yeah, even on the rework thing, too, is like a TG like 130 board will lift pads like crazy. Like when I first started doing boards as a hobbyist. I was buying cheap, the cheapest boards I can ever get. And I didn't even know the teacher and department like Teach you like 90 or 100 or something like that. And it's just the moment we thing is like the moment you had any kind of rework, or you left your soldering iron on a pad too long, the pattern would lift. Oh, and I just thought that was normal until I started using like TG 170
boards. Or if you have if you have to hot air, an IC O yeah, ever have to do that unload TG boards, you have you have a much, much higher chance of D Lam. And just like actually bubbling in the in the board, and then it's effectively garbage. So another thing that you'll see is trace slash base. A lot of times you see that as two two numbers and numbers slash remember, where trace face is what is the minimum width of traces on your board? And then what is the minimum spacing in between traces on your board? I think a lot of people get confused about this one, because they're like, Oh, my EDA tool allows me to put a 4000 straights on the board and I put them to 1000s away from each other. And like yeah, of course your EDA tool will allow you to do anything. But you know, if you're asking for tolerances in that, you know extreme than your price is going to go through the roof. So you'll it's always worth asking yourself like what first of all, like, what is the minimum pitch of like, out of all the ICS on my board, which one has the tightest pitch that one's probably going to define what your tray spaces on your board so if you're working with like big monster chips and I say monster like NYC AIDS or something like that. If that's like the the the tightest pitch you have well then you can effectively manufactured the cheapest boards because you don't need really tight spacing. But if you're if you're talking about really, really tight BGA or something like that, you might need to spend some extra money to get your tray space a little bit tighter. So the smaller your traces and the closer they are, the more expensive your board gets. That's just the rule of thumb. Minimum hole size is something as well I see a lot of problems with people just like putting really really tiny vias on boards that have no reason to have really, really tiny vias on them. And vias are those tiny little, like 3000 Cold vias, oh, 4000s, annular ring, you know, something like super tiny. In fact, it's a what i've what I've found in my own designs that tends to work really well is I have default via sizes that I use for most of my designs, and they're fairly big, like 12 Bow hole 24th out annular ring that's actually a pretty size that's
And here's the thing I Start with that. And if I can actually pull the layout off with, like, if you start with a blank canvas with a big via, and you actually pull it off, great. If I get to the point where I'm like, I just can't do this layout without going smaller. Okay, fine, then I then I figured it out. But if I start small, and then I screw up the entire design of like, well, I just added cost for no reason whatsoever. Yeah,
I do a very similar thing, except my spec is tight. I call it the 1010 1010 mil trace. 10 mil spacing. 10 mil drills.
Yeah, you know, okay, so we found that eight eight is with with Trey spacing, you don't incur a bunch of extra costs down to eight, eight.
Correct? Yeah. MX five, you have to go below 550. That's
pretty awesome. Actually. Yeah, yeah. So yeah, eight, eight, and then big chunky, V. is tends to me things.
Yeah, I just start with 1010 10. Is my defaults. Because also sounds cool.
Excellent. That's, that's that's a pretty good rule of thumb, because 1010 10 is probably not going to cost you extra at most.
I've never had to incur any extra cost ever been able to do like, I think pin guitars old? No, I think that back pentire has got some six mil on it. But it doesn't, does what I'm building. It doesn't incur any cost. But yeah, I start with 1010 10.
So the next thing on the list is surface finish. So how your pads are actually plated. So are you okay with doing hassle or lead free hassle, because those are going to likely be your cheapest hot air solder leveling things what. And then, then there's a handful of other ones enough being one of the industry favorites. But there's got, there's at least three or four more out there. Typically hassle is just your, your cheapest across the board. If you can get away with lead. If your industry allows for it, then you probably know that but don't just go and click hassle on your PCB guy just because it's like, well, that's cheap. And like that works out well, you might be getting yourself in a trap there. So sort of the this is the opposite extreme. Like if you go to the way cheap side, you might be violating some laws by just picking hassle. But do you really need like, organic plating on your boards? is I mean, that's that's an extra cost on top of things I like
I like my plating be lit to be free range.
organic free range.
Um, no, no, this is a good one because background we default to in egg, but we allow other options. And main reason is because we don't know if we if you need to be how planar your board needs to be. This goes back to how planar your board needs to be. If you've got big parts or all through hole, then do lead free hassle all the way up. Super easy to solder is like a dream. Yeah. Whereas Okay, now you got a BGA that's got 100 pins, everything's got to stay flat. That's the that's the benefit of enig is Ineke is super flat and console allows it so that the paste will lay super flat, and you'll get good reflow on it. So one of the that's the main differences. That's why which one would you pick? How point how coplanar do your board needs to be because hassle is if you look at it under microscope, it's pretty wavy.
Oh yeah. Well, I mean, when they say hot air solder leveling like it literally they dip it and then a big like air blade goes across it and just blow solder off of it. Like it's not very level. Yeah. hassle with lead is a dream to solder though. Like because like everything already has solder on it. Yeah. Okay, so this last one in the easy group, I find people violating all the time for no reason whatsoever, and it's super annoying. It's copper weighed. So many. I've seen so many situations where people just arbitrarily think that they need heavier, thicker copper on the outside of their board. And they don't have a good reason as to why a lot of times extra copper weight is there. To aid in current capability across the board. You would be surprised how much a trace how much current a trace can actually conduct or carry. There's plenty of online calculators if you need to figure out you know your temperature rise of your traces and how much you can actually handle through a trace. But if you're just running like an Arduino, you don't need three ounce copper on your board. Like it's just See, it's ridiculous. And there's not necessarily a big benefit, you don't get like better signal integrity from it.
And this goes actually back to my 1010 1010 mil 10. Mil tracing is a 10 mil trace over i reasonable distance on a circuit board is like one amp of current capacity. Yeah, it's a ton. Yeah. It's actually interesting. This is, once you get past an amp, though, how big your traces need to get grows quite big.
Oh, for sure. Yeah, like if you need to actually pass like huge amounts of current through a board. You need to you need to pay really special attention to all of all of those. But if you're just trying to escape your microcontroller, all of your traces don't need to be 50,000. You know, you're just not going to you're not benefiting from doing that.
The and this is a really good example of what I did to reduce costs on the penetrator. is there's some traces or some SERPs? I wouldn't say it's tracing some netlist on my circuit board on a circuit board design need to handle 10 amps. Okay, at like 50 volts. So it's, that's quite a bit of power. And I could have easily had been like, Oh, yes, drop two outs with three ounce copper on the board, that would actually solve like, a lot of design problems. But I wanted the, that those boards, and these are actually large PCBs as well, they were quite expensive to run in that way. And so what I just did instead was, oh, I'll just run a trace on the top and the bottom and then just via stitch them together.
Done. Yeah, it's like two ounce copper. Except not, there's a lot of tricks you can you can do to avoid these kinds of things. Because adjusting the copper weight of your board. It will it increases the cost of your board pretty quickly. It skyrockets really fast.
And not to mention how much it's not really difficult, I guess, for your CME to assemble in because there's, they know about two ounce and three ounce copper. And the thing is, you have to adjust your reflow profile. So your, your first couple boards through your machine might not have the best or panels who might not have the best yield until they iron that out.
Absolutely. Yeah. If you just arbitrarily putting two ounce copper on your external layers and add one ounce on your internal layers. It takes a lot of extra heat to get that board into reflow. And so the default reflow profile on at your CM, it likely isn't going to cut it. They probably have to go turbo nuclear on that.
Oh, just a little slower. A little hotter, then yeah. Or both?
Well, yeah, whatever works for the recipe, right? Yeah, so
Oh, that that mirror the old Bravo reflow oven we had at macro fab way back in
every every every zone was 100% 100%. Yeah. How many times did you replace heat zones on that thing.
So this old reflow oven is a is a Bravo. And it was lead free compliance. However, if you actually bought them it is if you actually read about like, people who use this machine, it was a lead it was a leaded reflow oven, that the company just slapped a lead free symbol on because yeah, it could totally get to 260 degrees Fahrenheit, or Celsius. No, it could barely get there. And so what would happen was or the heaters can get there. The problem is all the supporting hardware can't handle that high of heat for that long of a duty cycle. And so basically fan bearings off all the blowers motors would just fail on it just cook and I ended up basically buying like high temperature bearings and then replace them like once a month.
Yeah, it was kind of awful. Yeah,
it was pretty bad. Because you could just hear the like one of the fans start screeching and then you're like okay, at the end of the day shifts Parker take them all apart, put new bearings and put them all back together. And I
think there was another time where the capacitors on the fan bit the dust too.
Yeah the capacitor because there were capacitor started blower motors, and they were melted onto the fans. And of course those are also really hot and the capacitors would fail.
We had a stock of those capacitors,
stock a bearings and capacitors
Yeah, these are these are the things that happen at your CM that you only hear here. You see I'm not going to pitch to you about the customer about their capacitors going out in their oven oven.
That was such a long time. Man that was like six years ago at this point now It was, it was before that was going on before everyone started this podcast. Oh, yeah. Oh, yeah, yeah. So.
So there's one other thing I kind of want to cover here. And this is the other segment. And I say it's not the easy ones to understand about controlling the cost of your PCBs, but it ends up being basically one element on your PCB that can really screw with your cost. And before I go into this, I realized there's a handful of things I haven't touched here, we could probably spend a lot longer and I just want to touch on like, these really obvious ones, like the things that are in your beyond my quote, stuff. However, this next these next items are not entirely in those online quoting things, and they can screw you really fast, especially if you've designed them in and you didn't know they're expensive, and they all reference vias. vias if you need to plug your vias or if you need to put conductive goop inside your vias. Or if you just vn pad, vn pad. Or if you just decided that your board needed blind or buried, or both types of vias, that's an excellent way to make your board costs skyrocket. Mainly because all of those things everything I just said there require that the not not only your CM, but your PCB manufacturer, they have to do special processes for every single thing. They're like, almost every PCB manufacturer has their path that they take to manufacture something but as soon as you start adding these kind of off ball, weird items on there, they have to either break their process or go to a different special process to handle these things. And they're difficult to get right. So they cost a ton of money. And I think Parker mentioned it last podcast, like vias are just expected on boards nowadays, but things like blind and buried vias are not necessarily expected and you end up paying per via into individual cost. And that adds up really, really fast. And to be frank, I've seen people input boards into to get quoted, where they didn't know that and they're just like, man, these blind and buried vias are really convenient. I can get signals anywhere all over the board, and their board just didn't even need it. And they just did it because EDA tool was like, Would you like to do this and then screw in the cost of their board and I had to redesign their board because it's like, oh, God, like, just the cost of the blind and buried vias was three times the cost of the board by itself, you know, because it was just pockmarked all over. And for those who don't know, blind and buried vias are vias that go from one layer to a different layer on a board, but potentially not the other layers. So like a blind via can go from one of the external layers to one of the internal layers, but not all the way through the board. And a buried via allows you to go from one of your internal layers to a different internal layer. So it's a via that you wouldn't even be able to see from the outside of your board. And if you think of a cross section of your PCB and you think of blind and buried vias, and then you ask yourself, How does somebody actually make this that's why it's expensive because as soon as you start thinking about it, like oh my god, this is gonna be really difficult to make and yes, that's, that's true. It is very difficult to make.
So what's really funny is long long time ago, also a long time ago, as four years ago at this point, actually yeah, for you know, five years five years ago DigiKey shipped out some some rulers to like I think we got them in our Mac like they sent us the macro fab a lot of people have these rulers now but on what on they have a blind via screen that says pointing to an arrow and you can't see anything and this is very via Yeah, it's a very big Yeah, there Yeah. Buried via and actually it says March 2016 on it and you go but I actually I'm actually going to take this to work tomorrow when X ray this Oh,
that's a great idea. Yeah. Did is one of their did they spend hours just on all of those moves? Or is that just like a convenient joke?
I think he's I think it's a joke, because you can't see it. Normally, so yeah. Although like
how great would it be if you X ray it and there's like Rick Astley in the in the internal layers.
So speaking to Digi key, this is a key with bumbled monk, it's a bumble monk. Yeah, on on our Slack channel showed our Slack channel some really cool technology that they've implemented at digikey and DigiKey is able to now print information on the backside of like cut tape. And so like what the value is and what the manufacturer part number and like a barcode and stuff, they print that on the backside. And so then now you can, like if you just have a piece of cut tape lying around and you know what's on the cut tape now,
super cool which, which if you've ever dealt with cup tight for five minutes, you'll know that this is actually a really cool thing. Because if as soon as you take some cut tape, and you leave it on your desk for a little bit of time you come back you're like I have no idea what that is. Yeah, what value is that? Get the multimeter right. Yeah, or Yeah, capacitors are even worse because they're just all the same color all the same size. Everything is the same and it's just like I have no idea. Is it people or is this the point 116 volt? I don't know. Yeah. So yeah, the the the information on the back is really cool. At the same time, I'm pretty sure Digi key will actually print your custom part number on there as well if you put that in one of their fields, I don't remember exactly how it works but so if you have internal part numbers that can be printed on the back as
well. That is really cool. So right now they're only doing it on eight millimeter tape, which is the majority of tape. I assume they're going to explain that to others though.
And if I recall right, I mean we can be corrected in in the Slack channel if we're wrong here but this this applies to a variety of parts at the moment and it's not necessarily an opt in kind of situation it's just if the part can be printed Digi key we'll be offering that I don't know exactly when this goes live. I know it will be sometime soon ish though. So when you start ordering ordering parts you'll just see it show up
I'm gonna check the reels that show up tomorrow
you guys probably get Digi key every day
and Mauser and like Arrow and everything you get like every single distributor every single day
like many many boxes of them right
so you know how at macro fab HQ so we expanded into the the Parker uniform place that's next door Yeah. And so and we moved like development stuff over to this is pre COVID moved him over the West Campus, like sales and all that stuff over there. And so that entire 10,000 square foot plus plus the new spot is right next door that's thinking about that's all like just parts parts just customer parts, Mauser parts did you keep part so many parts I can't wait I hopefully I opened up a box tomorrow in and I see this that'd be cool. So that was the back of engineering podcast where you host perfect don't miss didn't Greg later everyone thank you. Yes, you our listener for downloading our podcast if you have a cool idea, project or topic. Let's see, you know, tweet us at Mac fab at Longhorn engineer at analog EMG or email us at podcasts at Mac fab.com Also check out our Slack channel. You can find it at Mac fab.com/slack
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