Typically, you buy a single board Linux computer. [Henrik] had a better idea, build his own ARM based single board computer! How did he do it? By not being scared of ball grid array (BGA) ARM processors.
Everyone loves the Raspberry Pi and Beagle Board, but what is the fun in buying something that you can build? We have a hunch that most of our readers stay clear of BGA chips, and for good reason. Arguably, one of the most important aspects of [Henrik’s] post is that you can easily solder BGAs with cheaply available tools. OSH Park provides the inexpensive high-quality PCBs, OSH Stencils provides the inexpensive stencils, and any toaster oven allows you to solder even the most difficult of components. Not only does he go over the PCB build, he also discusses the bootloader, u-boot, and how to get Linux running.
Everything worked out very well for [Henrik]. It’s a good thing too, cause we sure wouldn’t want to debug a PCB as complicated as this one. What projects have you built that use a BGA? Let us know how it went!
If you’re free the first week of April and don’t mind sitting on a plane for a looooong time you should check out the Hacker Camp that Dangerous Prototypes is planning. We’re sure you remember [Ian Lesnet] who is a Hackaday Alum, creator of the Bus Pirate, and geeky world traveler. Now’s your chance to try out what to him is a way of life.
The event is April 3-5 in Shenzhen, China. Although marketed as a “Hacker Camp”, to us it sounds more like training for those interested in running hardware companies that use the Shenzhen manufacturing district as the anchor of their supply chain. Part of the prep-work for the trip includes submitting board files which will be fabbed and ready for you on the first day. [Ian] and his crew will be your guides for the culture of the area; complete with meals and bar time. But there are also soldering workshops as part of the package. Don’t pooh-pooh the idea. This is unhuman soldering… BGA and QFN soldering instruction from the people who repair cellphones and other microelectronics.
This [Rick Steves] style adventure is the first that we remember hearing about that targets the open hardware community. But we must admit, it sounds like a lot more fun than a European river cruise!
And here we’ve been complaining about Flat Pack No-Lead chips when this guy is prototyping with Ball Grid Array in a Wafer-Level Chip Scale Package (WLCSP). Haven’t heard that acronym before? Neither had we. It means you get the silicon wafer without a plastic housing in order to save space in your design. Want to use that on a breadboard. You’re crazy!
Eh, that’s just a knee jerk reaction. The wafer-level isn’t that unorthodox as far as manufacturing goes. It’s something like chip on board electronics which have that black blob of epoxy sealing them after the connections are made. This image shows those connections which use magnet wire on a DIP breakout board. [Jason] used epoxy to glue the wafer down before grabbing his iron. It took 90 minutes to solder the nine connections, but his second attempt cut that process down to just 20. After a round of testing he used more epoxy to completely encase the chip and wires.
It works for parts with low pin-counts. But add one row/column and you’re talking about making sixteen perfect connections instead of just nine.
SMD components may be a little challenging for the home builder – even though the’re inordinately practical for homebrew PCBs – but if you play around with electronics and solder long enough, you’re eventually going to run into the horrors of BGA parts. Instead of convenient pins, BGA parts have tiny metallic balls on which solder is applied, a board is thrown through a reflow oven, and hopefully at the end, everything works. Sometimes these balls corrode or otherwise need to be reflowed. This isn’t an easy process, so [Edmar] came up with his own BGA rework station that costs much less than commercial offerings.
[Edmar]’s build began when he wanted to repair a graphics card. A common error on his Amilo XI2428 graphics card is having the small balls on the underside of the chip corrode, leaving the user with a non-functional graphics card. Towel trick notwithstanding, the easiest way to fix this error is to heat up the card to above the melting point of solder, removing the chip, and resoldering it with careful application of solder paste.
[Edmar]’s reflow station is made of an electric skillet for the bottom of the board, an infrared lamp for the top side of the board, and control circuitry constructed from an ATMega128, temperature sensors, and a huge power supply. The temperature is controlled via USB by a computer, allowing [Edmar] to set a temperature profile as recommended by the BGA chip’s data sheet.
Right now, removing a BGA chip works great, but [Edmar] is still working on the tech necessary to replace a BGA chip on a board.
Okay, we think it’s questionable when people say they have no problem soldering QFN packages, but BGA? Granted this chip has far fewer balls on it than many, but it’s still quite impressive that [Xevel] was able to solder this BGA breakout by hand.
The chip you see above is a TMP006 infrared temperature sensor from TI. [Xevel] picked up the part but didn’t want to break the bank when prototyping by buying a proper PCB to host it. There are only eight conductors on it, arranged in a grid with 0.5mm pitch. That didn’t seem to scare him off, as the video after the break shows him connecting each to a conductor on a hunk of stripboard.
[Xevel] mentions that this is a dead-bug style project. Usually you glue the part upside down when using that technique, but it needs line of sight to get an accurate temperature reading so he first cut a hole in the substrate. We’d bet he’s using wire-wrapping wire to make the connections. It’s a very fine solid core wire which is perfect for this kind of work.
Continue reading “Hand soldering BGA parts should be a circus act”
In an effort to ease the process of soldering Ball Grid Array (BGA) chips at home [Roger] rigged up a hands-free solution for his hot air equipment.
The main component in the build is an Aoyue hot air rework station that he already had in his workshop. He wanted an adjustable mount that would hold it steady when reflowing parts so he hit Amazon and bought a $14 articulated lamp. After ditching the funnel-shaped shade he bolted a cable clamp to the socket housing. This can be tightened on the hot air wand, with the spring tension of the lamp making it easy and quick to reposition the nozzle. [Roger] sent this project directly to our tips line and we’ve embedded the rest of the project images after the break.
If you’re looking for a more DIY rework solution you should checkout this hot air pencil hack. It uses a desoldering iron, a fish pump, and some metal mesh as a heat sink to put out a stream of very hot air.
Continue reading “Hands free hot air station”
Having just received a shiny set of PCBs from the fab-house [Devbisme] needed a way to solder the main chip in place. It has a Ball-Grid Array footprint which is notoriously difficult to populate in a home lab. But he makes it look pretty easy and decided to share a video tutorial of the process.
The main tool he used is the paint stripper (heat gun) seen above. Since he didn’t have his own fancy reflow oven he made things work with the gun as his heat source. First he applies a generous layer of liquid solder flux to the BGA footprint on the board. Next he melts some solder onto the tip of his iron and uses it to tin all of the board’s BGA pads. Then it’s time for the critical step of positioning the chip. He uses vacuum tweezers to set it in place, and traditional tweezers to fine-tune its position. From here he heats with the paint stripper for two minutes, starting far above the board and slowly moving closer, with the reverse at the end of the soldering process. Once cool the board is cleaned with distilled water and blown dry with compressed air. After a visual inspection he finishes the application with a 30 minute stay in a 300 degree oven. We’ve included the video after the break for your convenience.
We’ve seen a similar technique used for replacing a chip on an already populated board.
Continue reading “BGA soldering with a paint stripper and stopwatch”