Tools of the Trade – Inspection

In the last episode, we put our circuit boards through the reflow process. Unfortunately, it’s not 100% accurate, and there are often problems that can occur that need to be detected and fixed. That’s what the inspection step is for. One could insert an inspection step after paste, after placement, and after reflow, but the first two are icing on the cake — the phase where most mistakes can be caught is after reflow.

There are a number of problems typical with a surface mount reflow process: Continue reading “Tools of the Trade – Inspection”

“I Can Reflow” Merit Badge

[Nick Sayer] can reflow, and he can prove it. He designed a simple blinking-LED circuit that uses SMD parts to, well, blink LEDs. That’s not the point, though. It’s designed to be a test platform for reflow soldering, and to use a minimum number of valuable parts. Plus, it says “I can reflow!” in exposed copper. What else do you want?

OK, as far as “proving it” goes, the badge isn’t 100% reliable — we hand-solder 0805 components all day long. But still, if you want to try your hand at reflowing a circuit board, and you don’t want to ruin a lot of expensive parts if you fail, something like this is a good idea.

The design is open, and it’s really the idea that’s the point here anyway. How about something that would be really onerous to hand-solder, but still cheap? We’re thinking a matrix of tiny LEDs and a shift register or something.

We just ran an article on a hand-soldering challenge board, this seems the perfect complement. Display both proudly on your desk and confound and amaze your coworkers!

Tools of the Trade – Reflow

In our previous issues in this series on making circuit boards, we covered placing solder paste and placing components. Now it’s time to bake our cake!

There are a variety of methods for reflowing a circuit board, but they all rely on a single principle: heat up the solder paste (a mixture of flux and solder) until the flux burns off and the solder becomes liquid, and then cool it down. Accomplishing this once or twice is easy; once you’ve played with a hot plate you’ll swear off through hole. Scaling it up and doing it repeatedly with high yield is extremely challenging, though. Continue reading “Tools of the Trade – Reflow”

PTC Heaters For Reflow Soldering

Reflow soldering – setting components on a PCB in blobs of solder paste and heating the whole assembly at once to melt all joints simultaneously – has been the subject of many ingenious hacks. Once it was the sole preserve of industrial users with specialist microprocessor-controlled ovens, now there are a myriad Arduino-controlled toaster ovens, hot air blowers, and hotplates that allow hackers and makers to get in on the reflow act too.

This morning a fresh idea in the reflow soldering arena has come our way. It’s not the most earth-shattering, but it does have some advantages so is worth a second look. [Analog Two] has successfully used a PTC heating element as a reflow soldering hotplate.

PTC heating elements are thermistors with a positive temperature coefficient. As their temperature rises, so does their electrical resistance. By careful selection of materials they can be manufactured with a sharp increase in resistance at a particular temperature. Thus when an electrical current is passed through them they heat up until they reach that temperature, then the current decreases as the resistance goes up, and they do not heat beyond that point. Thus as heaters they are intrinsically self-regulating. From our point of view they have another advantage, they are also cheap. Fitted as they are to thousands of domestic heating products they are readily available, indeed [Analog Two] found his on Amazon.

The heater chosen was a 200W 110V model with a temperature of 230 Celcius to match the solder he was using. They are also available for other mains voltages, and even at 12 and 24V for automotive applications. He reports that the time to reflow was about 90 seconds.

We’ve mentioned the advantages of this heater as its price and regulated temperature. Looking at the pictures though a disadvantage is its size. This is a reflow plate for small boards. There are larger PTC heater elements available though, it would be interesting to hear people’s experiences reflowing with them.

Hotplates for reflow soldering have featured before a few times here at Hackaday. We recently had this tiny plate, but we’ve also had a PID-controlled plate, and an Arduino-controlled domestic hotplate. We’re sure this is an avenue with further to go.

Hackaday Links: May Day, 2016

Humble Bundle is a great way to fill up your Steam library – just pay what you want, and get some indie video games. The Humble Bundle is much more than video games, because No Starch Press just put up a bundle of books on hacking. No, there are no books about wearing balaclavas and using laptops with one hand. I haven’t written that book yet. There’s some choice books in this bundle, including [Bunnie]’s Hacking the XboxAutomate the Boring Stuff with Python, and Practical Malware Analysis.

The Raspberry Pi camera – the $25 add-on webcam that plugs directly into the Pi – is getting an upgrade. The original camera was a five Megapixel sensor that was EOL’d at the end of 2014. The Raspberry Pi foundation bought up a lot of stock, but eventually there would be a replacement. The new sensor is a Sony IMX219 eight Megapixel deal, available at the same price. We assume a NoIR version without the IR filter will be released shortly.

Here’s a little hardware review that doesn’t quite merit a full post. The Raspberry Pi Zero is great, and will be even better once production ramps up again and stock lands in warehouses. One problem with the Zero is the lack of USB ports, leading to at least two Hackaday posts with the exact same headline, ‘Yet Another Pi Zero USB Hub‘. Obviously, there’s a market for an easy to use USB hub for the Zero, and this company is stepping up to fill the need. The killer feature here is the use of pogo pins to tap into the USB differential lines, power and ground pads on the bottom of the Pi Zero. The USB hub is based on the popular FE 1.1 4-port USB hub controller, giving the Pi Zero four USB 2.0 ports. Does it work? Yeah, and it’s only $10. A pretty neat little device that will be very useful when Pi Zeros flood workbenches the world over.

It was announced in 2014, released in 2015, but the STM32F7 hasn’t seen a lot of action around these parts. A shame, because this is the upgrade to the famously powerful STM32F4 microcontroller that’s already capable of driving high-resolution displays through VGA, being an engine control unit for a 96 Ford Aspire, and being a very complex brushless motor driver. The STM32F7 can do all of these and more, and now ST is cutting prices on the F7’s Discovery Board. If you’re looking for a high-power ARM micro and don’t need to run Linux, you won’t do better elsewhere.

Need to reflow a board, but don’t have a toaster oven? Use a blowtorch! By holding a MAPP blowtorch a foot away from a board, [whitequark] was able to successfully reflow a large buck converter. There’s a lot of water vapor that will condense on the board, so a good cleaning afterward is a good idea.

A few weeks ago, [Mr. LeMieux] built a 360 degree, all-metal hinge. He’s been up to something a little more dangerous since then: building piles of mini table saws. Small table saws are useful for miniatures, models, and the like. [Mr. LeMieux]’s table saw is a piece of CNC’d aluminum, with a bearing and saw arbor that attaches to an electric drill. Dangerous, you say? Not compared to the competition. Behold the worst forty dollars I’ve ever spent. This Horror Freight mini table saw is by far the worst tool I’ve ever used. The bed was caked with streaky layers of paint, uneven, the blade wasn’t set at 90 degrees, and the whole thing was horrifically underpowered. Trust me when I say the CNC electric drill version is safer.

Tiny Hotplate Isn’t Overkill

When working on a new project, it’s common to let feature creep set in and bloat the project. Or to over-design a project well beyond what it would need to accomplish its task. Over at Black Mesa Labs, their problem wasn’t with one of their projects, it was with one of their tools: their hot plate. For smaller projects, an 800W hot plate was wasteful in many ways: energy, space, and safety. Since a lot of their reflow solder jobs are on boards that are one square inch, they set out to solve this problem with a tiny hot plate.

The new hot plate is perfectly sized for the job. Including control circuitry, it’s around the size of a credit card. The hot plate is powered from a small surplus 20V 5A laptop power supply and does a nice 4 minute reflow profile and cools off completely in under a minute. Compared to their full-sized hot plate, this is approximately 29 minutes faster, not to mention the smaller workspace footprint that this provides. The entire setup cost about $20 from the heating element to the transistors and small circuit board, and assuming that you have an Arduino Pro sitting in your junk bin.

It’s a good idea to have a reflow oven or a hot plate at your disposal, especially if you plan to do any surface mount work. There are lots of options available, from re-purposed toaster ovens to other custom hot plates of a more standard size. Overkill isn’t always a bad thing!

Continue reading “Tiny Hotplate Isn’t Overkill”

BGA Hand Soldering Video

By 2016, most people have got the hang of doing SMD soldering in the garage–at least for standard packaging. Ball Grid Array or BGA, however, remains one of the more difficult packages to work with [Colin O’Flynn] has an excellent video (almost 30-minutes, including some parts that are sped up) that shows exactly how he does a board with BGA.

Continue reading “BGA Hand Soldering Video”