The Ball Grid Array, or BGA package is no longer the exclusive preserve of large, complex chips on computer motherboards: today even simple microcontrollers are available with those little solder balls. Still, many hobbyists prefer to stay with QFP and QFN packages because they’re easier to solder. While that is a fair point, BGA packages can offer significant space savings, and are sometimes the only choice: with the ongoing chip shortage, some other package versions might simply be unavailable. Even soldering doesn’t have to be complicated: if you’re already comfortable with solder paste and reflow profiles, adding a BGA or two into the mix is pretty easy.
In this article we’ll show that working with BGA chips is not as difficult as it may seem. The focus will be on printed circuit board design: how to draw proper footprints, how to route lots of signals and what capabilities your PCB manufacturer should have. We’ll cover soldering and rework techniques in a future article, but first let’s take a look at why BGAs are used at all.
In today’s episode of Diminutive Device Technology Overview, [Sprite_TM] is at it again – this time conquering the HC32L110. A few weeks ago, we have highlighted the small ARM Cortex M0+ microcontroller, which is outstanding because of its exceptionally small size. We also pointed out a few hurdles, among them – hard-to-approach SDK and documentation, and difficulties making and assembling a PCB for such a small BGA. Today, we witness how [Sprite_TM] bulldozed through all of these hurdles for all of us, and added a few pictures to our collective “outrageous soldering” galleries while at it.
First, he figured out an example layout for this MCU that’s achievable for us even on a cheapest 2-layer board from JLCPCB, keeping distances within the generic tolerance standards by snubbing out a few pins. As a result, we only lose access to four GPIOs – those will have to be kept as inputs, so that nothing burns out. However, that’s the kind of tradeoff we are okay making if it helps us keep our PCB small and lightweight for projects where these factors matter. After receiving the resulting board, he also recorded a short tutorial on soldering such packages at home with a mere hot air gun and a few bare necessities like flux and tweezers – embedded below.
It doesn’t end there, however, as he decided to work around the GPIO fanout limitation in a non-intended way. Evidently, [Sprite_TM] decided to have some fun, taking a piece of regular 0.1″ spacing protoboard and deadbugging the chip with magnet wire, much to our amusement. The resulting contraption, pictured above, worked – and this is ever something you’d like to be able to achieve yourself in times of dire need, whether you make something work or simply to be entertained by making use of a cursed mounting technique, there’s an one-hour-long livestream recording of how this magnet wire contraption came to be. And, of course, that wasn’t the last thing to be shared.
Not a rhetorical question! This week we consider the most micro microcontroller: the HC32L110. It’s the new title holder of the smallest ARM Cortex M0+ part. But could you actually use it?
I remember way back, when I first learned to solder surface-mount components. It was fiddly at first, but nowadays I don’t use through-hole components unless someone’s twisting my arm. And I still do my soldering myself — down to 0603 really isn’t all that bad with an iron, and below that, there’s always the heat plate. My heat plate has also gotten me through the two times I’ve actually needed to put down a ball-grid-array part. It wasn’t as bad as I had feared, honestly.
So maybe it’s time for me to take the BGA plunge and design a board or two just to get more familiar with the tech. I probably won’t dive straight into the deep end, like the featured chip here with 0.35 mm ball pitch, but rather stick with something that the cheap PCB services can easily handle. My experience tells me that the best way to learn something is just to test it out.
Now, off to go part shopping in the middle of a chip crisis! Wish me luck.
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We’ve been contacted by [Cedric], telling us about the smallest ARM MCU he’s ever seen – Huada HC32L110. For those of us into miniature products, this Cortex-M0+ package packs a punch (PDF datasheet), with low-power, high capabilities and rich peripherals packed into an 1.6mm x 1.4mm piece of solderable silicon.
This is matchstick head scale computing, with way more power than we previously could access at such a scale, waiting to be wrangled. Compared to an 8-bit ATTiny20 also available in WLCSP package, this is a notable increase in specs, with a way more powerful CPU, 16 times as much RAM and 8-16 times the flash! Not to mention that it’s $1 a piece in QTY1, which is about what an ATTiny20 goes for. Being a 0.35mm pitch 16-pin BGA, your typical board house might not be quite happy with you, but once you get a board fabbed and delivered from a fab worth their salt, a bit of stenciling and reflow will get you to a devboard in no time.
Drawbacks? No English datasheet or Arduino port, and the 67-page PDF we found doesn’t have some things like register mappings. LILYGO promised that they will start selling the devboards soon, but we’re sure it wouldn’t be hard for us to develop our own. From there, we’d hope for an ESP8266-like effect – missing information pieced together, translated and made accessible, bit by bit.
When it comes to soldering such small packages, we highly recommend reflow. However, if you decide to go the magnet wire route, we wouldn’t dare object – just make sure to send us pictures. After all, seems like miniature microcontrollers like ATTiny20 are attractive enough of a proposition that people will pick the craziest route possible just to play with one. They say, the madness of the brave is the wisdom of life.
The all-in-one Raspberry Pi 400 computer is a capable device, but those seeking its maximum power may be disappointed by its 4 GB of memory. When the Pi 4 and Compute Module 4 have double that figure, surely the Pi 400 could catch up! A reddit user called [Pi800] rose to the challenge by replacing the 4 GB chip from the Pi 400 with the 8 GB chip from a Pi Compute Module, resulting in the so-called Pi 800, a working 8 GB all-in-one Pi.
As a piece of work it’s a deceptively straightforward yet extremely fiddly piece of soldering that requires a steady hand for even the most skilled of solderers. What takes it beyond the norm though is the reballing process. A ball-grid-array chip has a grid of small balls of solder on its underside that make the contacts, and these melt when it is soldered so require replacement before reworking. This is normally done with a template of carefully aligned holes to line up balls of solder in a stream of hot air, but lacking the template in this case the job was done by hand, laboriously ball by ball. A soldering task we’d hesitate to take on ourselves, so we’re impressed.
The result is an 8 GB all-in-one Pi, and it’s honestly not beyond the realms of possibility that an official version of this mod could be a future Raspberry Pi product. Perhaps we’ll wait for that, but should you be impatient then at least it’s possible to roll your own. It’s certainly not the first BGA memory swap we’ve brought you.
If this sounds familiar, it’s because he tried the same trick with the RTX 2070 back in January but couldn’t get it working. When he first published the video showing the process of desoldering the 3070’s eight Hynix 1 GB memory chips and replacing them with eight Samsung 2 GB chips he hit the same wall — the card would boot and detect the increased RAM, but was unstable and would eventually crash. Helpful hints from his viewers led him to use an EVGA configuration GUI to lock the operating frequency which fixed the problem. Further troubleshooting (YouTube comment in Russian and machine translation of it) showed that the “max performance mode” setting in the Nvidia tool is also a solution to stabilize performance.
The new memory chips don’t self-report their specs to the configuration tool. Instead, a set of three resistors are used to electronically identify which hardware is present. The problem was that [VIK-on] had no idea which resistors and what the different configurations accomplished. It sounds like you can just start changing zero Ohm resistors around to see the effect in the GUI, as they configure both the brand of memory and the size available. The fact that this board is not currently sold with a 16 GB option, yet the configuration tool has settings for it when the resistors are correctly configured is kismet.
So did it make a huge difference? That’s difficult to say. He’s running some benchmarks in the video, both Unigine 2 SuperPosition and 3DMark Time Spy results are shown. However, we didn’t see any tests run prior to the chip swap. This would have been the key to characterizing the true impact of the hack. That said, reworking these with a handheld hot air station, and working your way through the resistor configuration is darn impressive no matter what the performance bump ends up being.
If you want to build cool things these days, you’ve probably had to master surface mount electronics. However, for many people, ball grid array (BGA) is still intimidating. Have a look at [VoltLog’s] video about his techniques for soldering BGA and inspecting that you managed to do it right.
He’s got quite a few tips about things like surface finish and flux selection. It looks easy when he does it. Of course, having a good PCB with good registration markings will help too.