Why are we still afraid of BGA chips?

追加: 2026-05-31

[00:00:00]How's it going, guys? Today, I wanted to do a quick little video on BGA chips, specifically tiny BGA chips like the ones that I used in my latest wireless sensor node project, [music] and why they aren't as scary as they might look.

[00:00:14]See, recently we've been having some issues with draining our tanks empty while the pump is still on, and only being able to check by peeking inside like this. So, instead of spending anywhere from about 50 to 250 bucks buying a commercial and proven solution for monitoring the water level, we decided to spend thousands of dollars worth of time designing something that could run off a 21700 battery and 1 W solar panel using an analog pressure sensor, which is meant to be one of the more accurate and robust methods. Only issue is, to take full advantage of this setup, we can't use the micro controller's built-in ADC. And if we want any sort of low-power operation, we can't keep it on and connected to Wi-Fi 100% of the time. Yet, we still want to be able to always monitor changes.

[00:00:57]Here's where BGAs come in. They allow for the many functions that solve these problems to be implemented in a much smaller space, and at times, they're the only option available or in stock for new technology.

[00:01:09]So, what exactly is a BGA chip? Well, BGA chips are essentially the smallest possible way to cram as many pins as possible into any given chip size.

[00:01:20]Instead of an array of leads at the perimeters of the package, it's a grid of balls underneath it.

[00:01:26]And it's important to note that there's a distinction to make if we bring chip-scale packages into the picture, [music] too. Because not all BGAs are even close to the same size as the actual silicon die, and not all chip-scale packages use balls. Without this tech, it would just be straight-up impossible for modern computing hardware to be advanced as it is, and for many more reasons than just size, which I'll explain later. But, this does come with some tradeoffs, usually. You see, when you go and bring that super tiny BGA chip into your PCB [music] layout, what you'll notice is that the only way to access the inner connections is to use special via tricks to get to a different layer, which quickly gets expensive and isn't worth it for the vast majority of prototypes. I'm not debating that.

[00:02:11]But, if you could somehow access all needed connections under the chip with standard PCB processes, like when your package only has two rows of balls, has removed or duplicate pins, or has enough spacing for vias, which by the way is enough for a whole host of power management, logic, and even entire microcontroller chips, there's really not much reason to continue avoiding this tech. Take this 0.4 mm pitch QFN in my recent project, for example. Even though the spacing from edge to edge of these pads is 8 mil, and this entire area here under the chip can have shorts that you won't be able to see at all, you wouldn't expect to raise costs of assembly in your prototypes, right? I wouldn't, either. I mean, this type of packaging is very common place amongst low-cost dev boards, like those based around an RP2040 or ESP32-S3.

[00:03:02]Now, let's move over to the BGAs.

[00:03:04]There's seven on this board.

[00:03:06]The smallest spacing out of them is for these load switches, just over 6 mil.

[00:03:11]All the others are actually spaced 8 mil or more. You, of course, can't easily inspect if there's shorts underneath, either. [music] Seeing this, what do you think is more scary for your PCB fab? This or this?

[00:03:25]I'm no expert. I mean, what do I know?

[00:03:27]I've never mass-produced or sold any of my designs, but from my perspective, the answer seems obvious. So, when I submitted the manufacturing files for this recent design to PCBWay using their easy-to-use KiCad plugin, it was great to see that when they came back with a quote a day or two later, the price of component assembly remained unchanged, as did the price of the circuit boards themselves. Meaning that I was pretty much able to save money using the newest chips for what I needed.

[00:03:54]It might have been better to use [music] a different more expensive surface finish, but that doesn't change the fact that these four BGA chips do work, and I don't see any reason why the other three shouldn't. PCBWay can source electronic components for your next project from a wide range of authorized distributors, which is great for when you want to get those newly released or uncommon parts without being locked into one company.

[00:04:18]And even with that aside, if you want top-tier PCB manufacturing and assembling services too, feel free to check them out in the description below, because the first 20 people who use this [music] coupon get $10 off orders over 30 bucks. Thanks again to PCBWay for sponsoring this channel, and let's get back to the video.

[00:04:38]Now, so far we've talked about what a BGA is and how you can easily use one in your next PCB, but we haven't talked about why you'd want to go through all that trouble instead of just using standard parts. So, to start with, we should ask, what changes when the connections between the die and solder pads are shorter and wider than any other package type? If we refer to Maxwell's equations, which were rewritten by Heaviside in the form we use today, we can see that the component of the magnetic field parallel with any given loop area, whether that loop is receiving or transmitting energy, is going to be smaller.

[00:05:14]So, essentially, less inductive coupling. And there's also going to be less capacitive coupling for kind of similar reasons, since it's pretty much like reducing the area of capacitor plates, and therefore reducing electric flux. Self-inductance, more commonly known as just inductance, is also lower, which means voltage spikes for a given transient are going to be smaller, and that's beneficial in the vast majority of circuits for many different reasons.

[00:05:38]So, it goes without saying that our PCB is probably less likely to fail EMC emissions and immunity tests when we swap out some other type of package for a BGA, the math behind how PCBs work seems endless, but that's not what this video is about. Even though I did weeks of research on the topic at the worst possible time. So, if you want to see a full video on some of this stuff, make sure to drop a comment down below with the word divergence. Apart from that, we also get benefits of not only lower electrical resistance, but also lower thermal resistance, at least to the solder pads themselves. Like, take this TSX0102 level shifter for example. Even though it's not going to be producing much heat, the thermal resistance between the die and the board in the DSBGA version is literally 7% that of the VSSOP version. And despite it being the smallest package in the whole lineup, it stays the coolest by a long shot. That's a big plus for overall reliability because semiconductor aging affects speeds and thermal stresses, which eventually lead to cracks, are significantly lower. This isn't always the case. Like, say you had a QFN with a big thermal pad that was 50 times bigger and heat sinks were not allowed. Yeah, it would probably win. So, it goes without saying that data sheets and thermal simulations, or at least educated guestimates, are your friend.

[00:06:58]So, I guess the long and the short of this video is that BGAs aren't just for million unit phone production runs or something like that. No, they're completely accessible to us hobbyists with the right ball layout. And in fact, I'd recommend using them whenever you can because of various reasons related to compliance and reliability. Before you go, I just wanted to say that my uni workload for these next 4 months is going to be significantly lower than it was in the past 4 months because I'm only taking one course instead of three.

[00:07:26]Also, within those three, there was a group project and we all know how those end up going. But yeah, I'm super excited to be pumping out some more robotics, power electronics, and home automation content. And if you're also excited, feel free to subscribe so you you miss all that. I'm also going to Electronex in Sydney next week, where you can try your hand out at the soldering competition and check out PCBWay's booth. So, hopefully, if you're also there, we'll see each other there.

[00:07:50]We can have a nice talk. But, other than that, I hope you enjoyed this video. I hope it provided you something valuable.

[00:07:56]And thanks so much for watching and continuing to support me. Bye.