Parker and Stephen gear up for DefCon 27 and discuss how custom transformers can change design philosophy.
AND!XOR comes to Texas to talk about #Badgelife, the craziness of DEFCON, and their new badge design.
John Adams joins Parker and Stephen to discuss IoT Security, Crappy IoT Devices, and WS2812B LEDs.
Visit our Slack Channel and join the conversation in between episodes and please review us, wherever you listen (PodcastAddict, iTunes). It helps this show stay visible and helps new listeners find us.
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!
Hello and welcome to the macro fab engineering podcast. We are your host, Steven Gregg and Parker Dolan, and this is episode 117.
is the last time we will do this until like episode 1000. We got the ball a lot of times because it wouldn't episode 101 10 101101 Yeah, and yeah,
episode one episode 10 Episode 11. Yeah. Oh my gosh.
Yeah, but the next time we can do that do a binary Joe could be episode 1000
You know what, I'm gonna make a pact with you right now. If we end up doing 1000 of these episodes, then we we must do that. Remember? Yeah, I'll be retired by that time. Yeah.
That's gonna be that's
not a shit to talk about.
That's like nine years from now. Ah, cool. Okay. Last week, you had we're talking about? No, you didn't talk about your sense last week? A little bit.
I just mentioned it. But but but you know, I've actually brought it in because I wanted to show Parker an interesting thing about it. This is
way nicer than the case I built you. Yeah.
And a lot more expensive. That's true, because that case, what didn't cost anything? $20. It was like nothing. So we're not actually going to be talking about this today. But I wanted to show Parker something, an artifact that's happening with it. And we'll talk about the symptom that belongs in a museum. Oh, yeah. Was it difficult? It's one of those ones where you have to like bring a bag of sand and you have to like quickly, like, swap it out. Yeah, or big or big balls gonna roll. These are the these are the other things I designed in my off time like big traps. booby traps.
Are you doing Star Wars though? Yeah, I
do. Yeah, we play Star Wars RPG. And I'm the Game Master. And it's my job to make movie traps. Okay, so I have this sitting right here. And will you please flip it on Parker? And tell me what happens?
It powers up for a brief moment, and then LEDs dim and then it cycles over and over again.
That's right. Okay. So flip it off, because I don't know how long it can actually do that. So I have a power module on this that that delivers. Positive and minus 12 volts and five volt rail. None of my modules actually use five volts. So that's just there. So it's only pulling current on the 12 volt and the negative 12 volt rail. Okay. And nothing particularly special there. Flip over my case real quick. I want to show you something. So look at there's one module in particular
got a lot of capacitors on it. Yeah. Did booked a lot. I did
booked a bunch of capacitors. So I want to talk a little bit about something that that people might run into. And this is not specific to synthesizer, this could be any circuit whatsoever. So I found out that with this circuit, I didn't have enough bypass capacity on it.
If those weren't bypass, those are bulk patents. Well, sort
of. Yes. But But check this out. So this this particular module is a low frequency oscillator. So it has to be able to deliver current that changes very slowly, it goes down to a the lowest frequency is a 10th of a hurt. So it changes linearly play a brown note. Oh yeah. Oh, the brownest. So it's a linear ramp at a 10th of a hurt well, you you know to get something to actually oscillate properly. That way you actually have to have pretty clean power supplies because you have this slow changing current that can actually screw things up. Well before these capacitors were on here, and I've got about 1600 microfarads of extra capacitance on this thing. Before they were on there. I wasn't getting linear ramps on a sawtooth wave. I was getting curved a curve. Yeah, and it wasn't a nice curve because the circuitry behind it is actually switching on I got it certain things it's called shark fin. Pretty much it wave design if you look on the right, you got a crappy design turn it into something good yeah, Newton just just rename it and that is a marketing sales ploy if I've ever heard it, right. They're sharp problem. Just make people think that they need your problem. Yes. Yeah. So So I started when I first found this problem. I was like, Damn, that sucks. Because really, it has to do a bit with my layout and it has to do a bit with how the circuit goes. I opted for a layout that's probably not the best for this and I was just kind of trying it out where all My chips are on power rails that are cute and beefy. But they all steel current sequentially on this on these rails. And so they're basically cross talking to each other. Gotcha. So I had to have enough bolt capacitance or bypass capping across the rails to make each one act independently. And the problem with it is, that module works fine now, everything's great. Why is it causing this device to my synth to oscillate on and off, it doesn't stay on. It's because the power supply module that I have is actually a switching mode. Gotcha. And it does not like to have that much capacitance on it. So the inrush current of all of those caps are causing it to just crap the bed and it goes into shut off mode. Well, as soon as it does that, all that inrush current goes away. And so it's like, let's turn back on. And it'll just keep doing that until it's
clean. Yeah, so I noticed the name. It's called micro Zeus, you've got a mega Zeus.
You know, the funny this company, they're called Tip Top audio. This this whole like case, plus the power supply is like a one unit you can buy, you can buy the Upgrade Pack, which is a higher current output for the Zeus. Like the boost pack, or something like, Ah, I wish it wasn't. So the the thing is like, it should be able to, it has way more of enough headroom to supply my entire my entire thing. So instead of spending more money on just brute forcing my way through it, I would rather redesign the circuit or find a dead bug way that I can put it in there such that it doesn't happen. And that if people haven't ever, like dealt with this before, a slow start circuit is actually a pretty good way.
Another term for that is soft start Soft Start.
Yeah. So it's basically a time delay. And
inrush, current limiter choke. Yes. And other ones.
In fact, a, like a giant inductors inductors. Yeah, once they get to a certain size, people stop calling them inductors. They call them chokes for this exact reason. Because they choke off that inrush current chokes were actually used a lot in power flies back in the day, because chokes were cheaper than caps to make. Yeah, back in the day,
it was just a ferrite ring. And you'd wrap copper around it. Yeah,
there wasn't anything special about it. That would make it that expensive. But nowadays, obviously is the opposite. Now the thing is chokes because you can make a reactive tank circuit with them. You can do a choke and a cap, they actually make an excellent filter. I'm not going to do that on this one. I could I could just slap some inductors on there. But I want to do an active device. So have you ever heard of a capacitance multiplier? No. So if you make an RC filter, just a resistor cap low pass and you put the junction between that to a the between the resistor and the cap, where they touch, if you put that to a base or gate of a transistor, and then you use the emitter as an output, you actually effectively multiply what that capacitance is in that RC circuit by the gain of the transistor. Gotcha. So if you have like a one nano farad capacitor, and a transistor with a gain of 100, you know, effectively have an active one micro farad capacitor. Yep, what's cool about that is you can take the benefits of the faster or slower charging times. But the transistor will literally choke off all of the inrush current. So you can that's that's a really, really cheap and easy way of getting more capacitance out of but the only
thing is your transistor has to be able to support how much current is flowing through it.
Yeah, right. Yeah. And you have to deal with the fact that if you're doing a BJT transistor, you will have at least point seven volts drop across it, or if you're using a MOSFET it's whatever that MOSFET is there.
It's on? Well, if it turns all the way on to saturation, then you're at like, whatever it's on. resistances Right. Right. So it can be anywhere from like hundreds of ohms. So like Milla ohms,
right? Yeah. Right and, and, and that'll, that depends on a bunch of things like your, your current, the current that is like your steady state current and just a handful of things. Regardless, I don't need the full 12 volt power supplies on this particular module, I can get away with dumping a little bit of juice in an active circuit. So instead of making it look ugly, with a bunch of dead bug caps on the back, I'm going to make a stop start Soft Start circuit right at the input and just blast it with a ton of extra capacitance because if I use if I use a multiplier, I can do one cap that is basically the same as like 1000 Micro ferrets. Yeah, and just multiply it up. So that doesn't always work. But it's a cheap way of kind of if you have some extra headroom in your power supply, you can actually kind of like fake more capacitance and in this case, I have plenty of capacitance because the circuit actually works, I just needed to smooth a little bit more. So this is a really good candidate for that.
So you keep the big capacitors on it.
The the capacitors that are currently in the circuit, not the ones that are dead bugged on the back, I'm going to pop the dead bugs off.
So how well I thought the problem was you just didn't have enough bypass there. So you needed that?
Yeah, well, I can use this active circuit as bypass really in between Yeah, Mm hmm. I didn't know that. Yeah. So also, most of my bypass is across the rails, not to ground. So from the positive 12 to Oh, okay. I'm considering if I want to, like double up and have, you know, the positive 12 the ground and the negative 12 the ground. There's a lot of options on there. But regardless, I just kind of wanted to bring it up because I was like, this happened. And I was like, I'll really okay, well, at least it's a topic for the podcast. Yeah. So So here's the thing. I'll actually that I got to step away from the mic real quick. So Parker can tell you what, what I'm doing here. But I want to show you like there's actually a really quick fix for it.
I had Steven stepping up. He's walking around the desk. He turned it on. It's doing its thing. He unplugged it and just gonna play it back in. Hey, it works now. So I guess the the inrush current of all the modules are causing this problem to
yes and no. Because if you just have that one module as the only thing plugged in, it's still
kind of with the stable state not being there for that power supply
yet. That's right. Yeah, so those caps are drawing too much. Yep. Before it gets into a decent spot. Now there is one more option that I could do. And it's kind of the easiest of them all options. I actually have some resistors right at the input of the power, the 12 volt rails for each module goes through 10 ohm resistors, I could probably make those 20 Ohm or I could probably make them 100 Ohm. And, you know, yes, they'll drop a little bit of voltage, but they might slow it down just enough for the power supply to kick on. The only problem is with that kind of solution that would work currently as it is, what would happen if I were to double my my module count? What if I added more load that wouldn't guarantee anything for the future? It's just if I really wanted it to work right now, without those ugly caps on the back. I could change some resistors but I don't care that
I buy a mega Zeus or two Zeus, two microservices dual Zeus dual Zeus
or or you know put a linear power supply in there not a switcher. Yeah. And then because the linear linear will not give up until until somebody loses. He will not stop. Yeah,
it will. It will. It will be the linear power supply that loses. It will burn up it will melt a hole in your desk.
You ask a linear power supply for more currently just goes Okay. Let's do it. Until Something Happens until something happens. Yeah, I mean, I shouldn't say that. If you ask a poorly designed linear power supply, it will do that.
Because some have like thermal cut off and no fancy stuff yet. current limiting what any What 78057 thermal cut offs. Oh yeah. So
I've gotten them there before.
I have in print on my wooden desk of the t o s o to two to zero footprint
from from burning and entering into my That's great. Yeah, yeah, like if you over yet now. Like if you ever look at something, of course you know what it looks like? But if you're like, Oh man, I don't know what it looks like. You can just put it in the footprint. Yeah, it's a 220 That's what you should do. You should burn in every package on every regular package. I was
actually because is that silly thing where like, you know how people get tattoos. But other people get brands.
You want you want to 7805 on your shoulder does a to
two to zero package brand.
That's like the nerdiest gang initiation ever. There's like a guy on a chair. He's like, Ah, it's burning
100 Watts into one of those guys.
That is great.
All right. So yeah, that's, that's my segment.
So we had two weeks ago, we had an exon Yep. We had zap. We had a bit stream and Iraq and Iran. And I think we talked to mentioned a little about building a badge for the fab. Yeah, for DEF CON. Cool. So I'm thinking if we do a quick like 10 minute like this, come up with some ideas.
Well, isn't it supposed to be secret? Or is the community designing it with us?
I could be but I was thinking, this is what I want. I wanted to be a belt buckle
That's so Texas. I love it. Exactly. Yeah.
And no one's done this yet. Yeah.
That's that's like bumping their buckles together. That's awesome. That is Yeah, no, I think we might get in trouble. This is this is one of the first ideas that our marketing person has put onto the podcast, clicking belt buckles. Yeah. Together. Thank you. I really like
it. I feel like I'm Captain Planet when they put the rings up, but it's like, belt buckles and said, Why don't we do that? Yeah, yeah.
So I was thinking making like Pokemon badges where they you got all these different elements and stuff. So you could collect like eight different
dye? Yeah, I was thinking because everyone does like custom lanyards. So you can do custom belts. Oh, do you have Max grab on the belt?
Are they? Are they ESD belts?
Probably not. Oh, we can get really nerdy suspenders.
That no, that might even be too far. I think you took it too far. We need to go back to clicking belts.
So it's got to have a lot of LEDs covered up. That's the thing.
Is it in the shape of a Texas?
Probably not. I'm thinking we'd have to just be a grid. And so you can put graphics so you can put Texas on it and stuff like that enough resolution. So you can get Texas on there. Gotcha. Though I don't, you'd have to have a really high pitch to like, even fit Texas on that. And
it's not going to have burning 78 Oh, fives on it right. No, no, we're probably do switchers
that keep power. Power drop down. Yeah. But yeah, I maybe Texas is too big to fit on a belt buckle.
Are you kidding me? The Rodeo is going on right now. I guarantee you that Texas is not like, there's probably 1000 People with Texas belt buckles that are you know, a foot wide. That's got to be so uncomfortable.
So belt buckle. Yeah. And so a lot of them have like these like, like puzzles and stuff. But they start those puzzles like months ago. So we're behind the time. Yeah. So I was thinking, what if we made a tool to help people hack badges? Ah, so do like a built in DLA.
I was just about to say yeah. Have a DLA. Yeah. But you know, it would be hilarious. Okay, this this makes me think of remember, I think his name is data from the Goonies. He had an Altoids can as a sound thing. No, it's totally The Goonies Yeah, really? Yeah. Yeah. We had an Altoids can and he and it flipped down and he had like a rescue rope that extended out of it.
This is Goonies too. Yeah,
there it is. Yeah, she she. Oh, no, no, no. You know what? That was it. Oh, no. Under his shirt. He had the the boxing glove. Yeah, it was on like a big like, extend. Oh, that's right. Yeah, yeah.
No, you're right.
It's actually it wasn't a rescue rope. I remember now he had a little it was a dart with a suction cup on and he shoots it out of his crotch and hits a hit the drum and like, like fishing reels it in. Yeah. So my thought was like, what if you had a DLA cable that kind of like extended out of this belt buckle? That would be awesome. Yeah.
You hook up to other people's badges and stuff. Yeah, I didn't hook it into your computer. So I started looking into that. This idea. Okay. And the bus pirate isn't open source DLA. Okay. And so we can basically pilfer pirate? Well, I guess fork it I guess you fork the bus pirate and make it a badge and put a ton of LEDs and that's that would make a pretty good badge. I think
that would be hilarious if it acted like a scope. But like somebody's like down looking at Oh, look at the waveform at the mind. Blown. That's so awkward.
That might require we could let's Okay. delay in it.
But we consider this. Remember that that oscilloscope DSO 138, that was like $2 or whatnot. I understand that's like, fake one fake ones and stuff. But they were able to pull it off for like super cheap. With like a full custom screen and everything on there like you could the firmware for that's open source. You could just take that and put a scope
and put the screen there.
Yeah, but it's green as a scope there. And like, yeah, if you need to go sniff a badge. So you got the belt sniffer
in our Slack channel. Let us know if you want us to do a delay or scope or both. Both would be nice. I think require a little bit too much time to do at least for this next year. Both for sure.
I'm almost I'm almost thinking like, if the belt, of course now we're getting expensive but but if the belt was like magnetic where you could either have a delay or a scope, you just kind of like clipping onto the front. Just like you pick if you're an analog guy or if you're a digital guy, you just magnetically clip on whichever one is your jam.
Oh, I got so next year we have to do okay, so this year is this because this is within the realm of getting done by August, right?
Maybe that's knowing us maybe,
but it's like you have to get done two months in advance cert your production run? Yeah, and a Kickstarter, so
you have to Yeah, cuz we don't know any electronics manufacturers. No, we don't know anyone who can do it know exactly by
is So next year. It's making a proper utility belts. Oh, like a Batman. Yes. Yeah. So you have like soldering irons and and scopes? And yeah,
if it charges or charges everything with you when you walk?
Oh, kinetic energy. Yeah. Charger.
It's a Yeah, it's a jewel thief. Yeah, jewel thief. So you so you know, you have to walk like 15 miles to be able to solder one joint, but it will do
it will do it. I can just imagine everyone just jumping up and down, charging their devices up like they plug their phone in. And that slides just like kangaroo jumping around it at DEF CON. 27.
Right. And, and they're never allowed back at DEF CON 28 deaths on a full on Hacker utility bill.
I liked it. Yeah, that's great. Hey, we can pull that off. Next year. So yeah, so yeah, let us know what what should our belt buckle do? What's like bound by gas next time? Yeah. So on the topic of delays, Sally, who builds all those really fancy delays that you can get? Yeah, so we have one here at the shop. We have like a Logic Pro eight, which is really nice. That's the mid model, right? Yeah. Mid range. Yeah. Like there's a saili. Like, normal. And then there's the pro eight and then there's a pro 16. Right. Yeah.
And the pro 16 It's the same speed. Right. It's just more channels,
more channels. Yeah. And so what they did is they there's a new firmware update that gets you the full USB 3.0 bandwidth now, huh? So you get 50% More speed.
Wow. Are you kidding? Yeah. For free. Well, way to go sailing. Yeah, that was pretty sweet. Cuz I know. I know a handful of companies that they would be releasing that as a whole brand new product right now.
Pull new. saili elite logic elite.
Oh my gosh.
What's up the Pro?
Commander? Commander. Yeah, Commander. The lieutenant is what we have. And then it goes to command commander. Yeah. So yeah,
that's pretty cool. They just said, yeah, if you have a CLE Pro Logic, yeah, you get this for free. Actually, kind
of like that. Logic commander. Logic commander. That's that's pretty good. I might use that as like a handle online.
I'll make it a module for your synth. Oh, that's
a great idea. Yeah, the excellent. One. One module that I've been thinking about making is a handful of guys make it it's super cheap. It's just gates. And that's it. Oh, like logic gates. Yeah, it just is just a bunch of inputs and outputs. And if you want to take like a sine wave and end it with a triangle that's filtered. You just plug them in however you want to watch commander Janek. That's the logic command.
That's an awesome that's yeah, you gotta do okay. That is?
Yeah. I really like that.
So next topic, so Oh, yeah. So thumbs up to saili for that. Oh, yeah.
Way to go. Yeah. An engineer made that decision, not a salesperson.
For sure. Well, maybe not. Yeah, you're right sales would not have done that. narky. wouldn't have done it. Yeah, yes. Yeah. All right, tented verse non tinted vias. Ooh, yeah. So what's the difference between them Steven
one is covered with stuff and one is not covered. What's that stuff? solder mask? Cool. So yeah, you know your basic So yeah, basically you can you can tell your board house to put solder mask goop over your via holes if you so want
to so wants to so why would you want to do that?
ingress of crap down in the hole if you want to cover that up? That's one reason.
Yeah, so I started looking into like, why you would? Mainly it's to keep solder paste from, you know, gooping down through your via, mainly if you're like vias are really close to pads or whatever, right? But it's like why would you Want a via that's all in the middle nowhere not to be kept or to be kept. Why would it matter? Oh, I'm not sure. So I was looking into that, like more into like, why would you want the keep that cats because it doesn't really matter. Was it? So like, okay, it doesn't really matter from like electrical perspective. Oh, actually you would hope it wouldn't. Yeah, um, but what I know is they use a liquid to do the solder mask and then they like, bake it might write your UV cure. But yeah, you beaker. So apparently though is this liquid doesn't make a perfect seal sometimes. And so it can has a hole in it. And so if you do like water washing or flux, that stuff can actually get in there.
I gotcha. It can't get washed out. Gotcha. And so it can corrode the car. Well, yeah, yeah. It's copper down there. With gold plated. Well, but maybe not.
It's not because they do solder masks first.
Yeah, yeah, yeah, you're right. Okay. I see. I see. Yeah. So you're preventing corrosion.
Yeah. So if you leave it unmasked, you prevent corrosion from building up from a, from stuff getting in there and then corroding with flux and stuff, and water. But if you leave it unmasked, eventually that gold tarnishes and starts corroding on its own. So it's, it's there's not a I was looking online, there's not a definite like what you should do. In this field,
he will. So the only place that I know of where it's just like, by default, a good idea is when you're doing like high identity VGA. Yes. And you've got a via in between a quad of BGA. Pads. You tent that
yes, because the dog boning of via in the pad. Yeah, you cap that because you do not want less paste to reflow off your
Yeah, cuz it's, it's a giant pain in the ass to fix a BGA. And it's even harder to figure out if you've actually made that mistake, if you know, looking down into a BGA is incredibly difficult. So you do everything you possibly can to make sure that BGA is gonna stick well, and each pad only is connected to what it needs to be connected to. So yeah, so yeah, open is kind of funky.
And yeah, so under BGA. Always cap. Yeah, if it's out in the open, it kind of doesn't. It seems like it doesn't matter, because there's pros and cons. Yeah, the pros of capping it is it prevents long term corrosion from happening. But as the other way, if you leave it, if you cap it, egress of water during the manufacturing process, or flux can stay in there and cause problems. Yeah.
I suppose you were really, if you were really into, like figuring out the environmental effects on your board. It's another layer of protection, if you wanted to, like if you were going to pot your boards, or if you're going to conform a coat them, you could have that on there as just another protection layer. So if you know, let's say you have a board that's going to be in the middle of a swamp in Louisiana, at 110 degrees for this entire life, it might be a good idea to, you know, consider some extra protection there. It's going to be wet all the time, it's going to be hot. Maybe that's a good situation for it. I don't know, I might be grasping at straws here. Maybe just thinking like, the only reason why you would cap something like that is to protect it against the environment. Yeah.
Or where you would conform a coda so it matter. So you would have it. I would say if you're conformal, coating your board, you would leave it open, so that you make sure it was clean. Before you conformal coating. Well, I
was just saying like two levels of protection. Uh, you know, another another thing I was just came to mind is like, if you have test points around your board, you might cover vias around a test point, in case like a probe would slip or something like that. You don't want to short out on something or touch something, it could
be a thing as you're doing prototypes, you might want to leave them uncapped, because they make a good test point and a good test point. Yeah. And they happen to hold your probe. As you're like doing something else with the other hand,
you know, I've actually, I've never experienced this, but I've read a handful of times on the internet where people are like, don't do that, because your probe can dig through that because yeah, vias are incredibly thin.
Oh, yeah. It's just the thickness of the electroplating. Yeah, plus whatever
film if they put one underneath, some, some manufacturers do, so. I've never experienced that. And when I know I'm going to use a VA as as a potential test pad. I'll make the annular ring a little bit bigger. But, you know, that's something to consider. If you're jamming test probes a lot down in one hole, you might actually break connection.
Yeah. Or like poke through into another layer. If it's a multi layer board. You could do that if you don't have enough isolation, because you got things like most time Your EDA tool put like 10 mils of isolation, which is not a lot. No. And your probe can easily just poke through, especially those like those really sharp ones. Yeah, awesome. Yeah. Cuz they're great because they like, Don't poke through like conformal coating and like flux and stuff.
Yeah. And they, they cut through oxide layers.
Yeah. Well, I could see those. Like, if you put it into a via and jabbed it, it would go through into another
layer. Yeah, if you caveman your board. That's what you can expect. Yeah. You know, okay, so there is actually another thing above and beyond this. We can touch on real quick but plugged vias. Yes. Have you ever done plug vias?
I have? I've had customers do it. We've had customers do it. Yeah.
I've plugged the VM myself. I've never asked for it though. Oh, just getting soldered down inside. Oh, okay. Yeah. Okay. So so a plug V is kind of like a glue in.
Its back to the power. No, this just brought it up these plugging vias is if you're doing wave soldering. Yeah, you don't want you don't want the wave to go up your via and spill out over your board. solder balls messing with other SMT parts and stuff. So you'd want to cap it then? Sure. But
if your via has a big enough hole such that the wave from? I mean, I guess you Okay, yeah, you're right. That's, that's yeah, that's a good good application there. Yes, that can happen, even with the selective solder. Yeah, we've seen that happen before on adjacent through hole pads and things. Yeah. So or you could plug your vias and they would solve that issue also, exactly. Which plugin via come to think about in a wave solder application might not even be bad because a plug via is basically they just squirt glue down into the hole of a cap over with the electroplating. Right. And then if you wave solder on top of that you created yet another layer of protection on top of that, because the wave solder is just going to stick to whatever that is. In fact, you see that a lot on like TV boards, and things like that they have little, like all the vias are just little domes. Yeah. You see, you see that all bunched in there and that application?
Interesting. I wonder that keeps corrosion down or something? Good. You're putting 10 on top of the finish?
I you know, I don't I'm not sure I you know, it wouldn't it wouldn't surprise me with those kinds of boards. They're meant to be as cheap as possible. They're probably not even gold plated. They probably just rely on the tin plating.
Yeah, the mother and be hassled finish and the factory might be just straight copper.
I have seen that before. Yeah, yeah. So you if you doing that you have to prepare the board ahead of time, though. Yeah, cuz that copper will tarnish if it just sits in a mirror.
We talked we talked about different types of finishes before there's that one. That's the Oh, the the organic one. Yeah, I betcha. That's what they use. Where it looks like Matt copper.
It looks like pre tarnished copper. Yeah,
I betcha. That's what they use. And then so they just wave the whole thing to put tin on everything. Yeah. Maybe. So plugged vias. Yeah. If you do via and pad underneath the BGA. Plug them do that. But some, like some processors or like some qf ends that have like thermal pads, you shouldn't plug those because you actually want the paste the cost suck away from that ground pad? Yes. Because then it sucks the package down and makes a really good co planar surface for it?
Well, I would say that's actually one of the biggest issues we run into at macro fan is that pads underneath components are improperly designed, and they lift components get lifted up. And the thing about it is like, in a lot of cases, they don't just lift the component, they might only lift, like, a few pins. Yeah. And then we've had situations where boards sort of work. And it's really hard to detect. And so follow the manufacturer's recommended thermal pads
especially the the paste, yes. Well, I always do even if a lot of times manufacturer will just be like yeah, whatever. Like there's the footprint, do whatever you want for the paste, like thanks. Yeah. Microchip. So as I was window, my pads
Okay, yeah, I'll
I'll put about I do about two thirds of the whole surface area is a good rule of thumb. And then if it's a thermal pad, I'll put vias through and to help suck even more away.
Yeah, and well, and vias help with dissipating heat to yes, they can get the heat away from the chip. Yeah, so don't go hog wild with the vias though, put, put a decent amount, but don't just make it like a giant like matrix of holes. Your board manufacturer, I'll hate you for that. So I think there's one one thing that's kind of good to talk about to kind of cap this off. How do you indicate tempted or plugged vias,
your solder mask layer?
Correct. So for a tented via just put solder mask over the the vias. Now, one thing that's important, if you do that, technically, it's correct. Technically, that is proper, it would not hurt if Well, let's put it this way. If if it's important that that via is tented and you want to absolutely make sure, include a note with with your board tell your manufacturer, yes, I did intend to do this because sometimes it might happen on accident. And the and they like we talked about last week, a board manufacturer can potentially change your design, this might be a situation where they're like, Oh, well, we're going to remove this map, because it is extra processing for them. So that is something to look at. Now, when it comes to plugging vias. You there's not like a direct Gerber thing for that. So you pretty much just have to like write a note to your
Yeah, the the way I like people to do that is to send us like a, an extra drill file. That is just the ones they want plugged. Yeah, so they give us one drill file. That's everything, all that good stuff. And then they send us another one it says these are the ones that we want plugged in kept over because a lot of times the the board manufacturer will charge you per plugged via, right, sometimes it's a flat charge. It just really depends. But so knowing which ones are plugged in which ones you don't want plugged is a pretty important.
Right, right. And you sort of traditionally the the way to do that above and beyond you know, yes, the the drill file, all of these notes technically get included on a fab drawing. So you create a fab drawing that shows you know there's actually a lot of different fab drawings you can do but but traditionally there's there's sort of like you you supply one fab drawing that shows all the different points and you can say hey, every drill hit that shows an X is plugged, every drill hit that shows a triangle is ah yeah is tented or whatnot. No McWrap doesn't do it that way because Mac fab the interface is like your fab drawing. Yeah, but but when it comes to plug VC still kind of have to tell neck. Yeah, so the extra dual drawing is is nice. So cool.
Yep. Anything else about tented vias I badge designs
I think we should tend and plug every via on the badge do I make it smooth? Make it smooth? Make it real smooth? Well, that was the Mac vibe engineering podcast we were your hosts Steven Craig
and Parker Domon these guys later Thank you. Yes, you our listener for downloading our show. If you have a cool idea, project or topic or views that you want to be plugged, text us at or no not Texas, tweet us at podcasts or McWrap. That's when you go off script and doesn't work.
You need another beer? Yep.
Ah, if you have a cool idea, project or topic that you want Steven and I to discuss, tweet us at Matt kraebel. Email us at podcast at macro calm. Also check out our Slack channel which we'll be talking about vias and stuff like that
plugin stuff. Sure.
You can plug your project on our Slack channel
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