Lead-Free Solder Alloys: Their Properties And Best Types For Daily Use

Lead-free solder alloys have been around for as long as people have done soldering, with sources dating back about 5,000 years. Most of these alloys were combinations like copper-silver or silver-gold and used with so-called hard soldering. That’s a technique still used today to join precious and semi-precious metals together. A much more recent development is that of soldering electronic components together, using ‘soft soldering’, which entails much lower temperatures.

Early soft soldering used pure tin (Sn), yet gradually alloys were sought that would fix issues like thermal cycling, shock resistance, electron migration, and the development of whiskers in tin-based alloys. While lead (Pb) managed to fill this role for most soldering applications, the phasing out of lead from products, as well as new requirements for increasingly more fine-pitched components have required the development of new solder alloys that can fill this role.

In this article we’ll be looking at the commonly used lead-free solder types for both hobby and industrial use, and the dopants that are used to improve their properties.

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Review: SanErYiGo SH72 Soldering Iron

When the Miniware TS100 first emerged from China nearly three years ago, it redefined what we could expect from a soldering iron at an affordable price. The lightweight DC-powered temperature controlled iron brought usable power and advanced features in a diminutive package that was easy in the hand, a combination only previously found in much more expensive soldering stations. All this plus its hackability and accessible hardware made it an immediate hit within our community, and many of us have adopted it as our iron of choice.

A surprise has been that it has attracted no serious competitors of a similar type, with the only iron mentioned in the same breath as the TS100 being Miniware’s own USB-C powered TS80. Perhaps that is about to change though, as before Christmas I noticed a new Chinese iron with a very similar outline to the TS100. Has the favourite finally generated a knock-off product? I bought one to find out. Continue reading “Review: SanErYiGo SH72 Soldering Iron”

A Newbie Takes The SMD Challenge At Supercon

First-time visitors to Disneyworld often naively think they’re going to “do” the park in three days: one day for the Magic Kingdom, one day for Epcot, and one day for everything else. It’s easy to spot such people, collapsed on a bench or dragging exhausted kids around while trying to make their way to the next must-see attraction. Supercon is something like that — a Disney-esque theme park for hackers that will exhaust you if you don’t have a plan, and if you don’t set reasonable expectations. Which is why I was glad that I set only one real goal for my first Supercon: take the SMD Soldering Challenge.

Now, while I’m pretty handy with a soldering iron, I was under no illusion that I would be at all competitive. All my soldering experience has been with through-hole components, and while I also used to doing some production soldering on fine-pitch connectors, the whole surface-mount thing is new to me. I entered mainly because I wanted to see what was possible coming in raw. At best I’d learn what my limits are, and at worst I’d fail spectacularly and provide grist for a “Fail of the Supercon” post. It’s a win either way.

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Fail Of The Week: How Not To Re-Reflow

There’s no question that surface-mount technology has been a game-changer for PCB design. It means easier automated component placement and soldering, and it’s a big reason why electronics have gotten so cheap. It’s not without problems, though, particularly when you have no choice but to include through-hole components on your SMT boards.

[James Clough] ran into this problem recently, and he tried to solve it by reflowing through-hole connectors onto assembled SMT boards. The boards are part of his electronic lead screw project, an accessory for lathes that makes threading operations easier and more flexible. We covered the proof-of-concept for the project; he’s come a long way since then and is almost ready to start offering the ELS for sale. The PCBs were partially assembled by the board vendor, leaving off a couple of through-hole connectors and the power jack. [James]’ thought was to run the boards back through his reflow oven to add the connectors, so he tried a few experiments first on the non-reflow rated connectors. The Phoenix-style connectors discolored and changed dimensionally after a trip through the oven, and the plastic on the pin headers loosened its grip on the pins. The female header socket and the power jack fared better, so he tried reflowing them, but it didn’t work out too well, at least for the headers. He blames poor heat conduction due to the lack of contact between the board and the reflow oven plate, and we agree; perhaps an aluminum block milled to fit snugly between the header sockets would help.

Hats off to [James] for trying to save his future customers a few steps on assembly, but it’s pretty clear there are no good shortcuts here. And we highly recommend the electronic leadscrew playlist to anyone interested in the convergence of machine tools and electronics.

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Cheap Stereo Microscope Helps With SMD

Soldering is best done under magnification. Parts become ever smaller and eyes get weaker, so even if you don’t need magnification now, you will. [Makzumi] didn’t want to shell out $400 or more for a good microscope so he hacked one from some cheap binoculars from the toy section on Amazon.

A lot of magnifiers aren’t really good for soldering because the distance between the work and the lens isn’t very large. The hacked ‘scope has about 4 inches of working distance, which is plenty of room to stick some solder and a hot iron under there. The resulting magnification is about 12 or 15X and he claims that the cell phone pictures he’s included aren’t as good as really looking through the eyepieces yourself.

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Field Expedient Soldering Iron Will Do In A Pinch

If you think [Dubious Engineering]’s moniker is just a name, have a look at the pretty terrible soldering iron hacked out of a lighter in the video below. No one is suggesting this is a good idea but in an emergency, maybe it would come in handy. We liked the use of a chopstick and the formation of a heat exchanger with the copper wire coil. It was a mild disappointment that you had to drill out the chopstick, but we think you could have figured out a different method with a little thought.

The use of duct tape, of course, lends it instant hacker credibility. We suppose this might be useful not just after the robot uprising, but if you had to make a few quick solder joints far away from power and you don’t have a battery-operated iron.

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Workbench Fume Extractor Sucks, But Has A Charming Personality

Shop safety is important regardless of what kind of work you do. For those of us soldering, that means extracting the noxious fumes released by heating up the solder flux used in our projects. [yesnoio] brings to us his own spin on the idea of a fume extractor, and it pulls out all stops with bells and whistles to spare.

The Workbench Assistant bot, as [yesnoio] describes it, is an integrated unit mounted atop a small tripod which extends over the working area where you’re soldering. Inside the enclosure are RGBW lights, an IR camera, and an Adafruit ItsyBitsy M4 Express driving the whole show. Aside from just shining a light onto your soldering iron though, the camera senses thermal activity from it to decide when to ramp up the server-grade fan inside which powers the whole fume extraction part of the project.

But the fun doesn’t stop there, as [yesnoio] decided to go for extra style points. The bot also comes with an amplified speaker, playing soundbites whenever actions such as starting or stopping the fan are performed. These soundbites are variations on a theme, like classic Futurama quotes or R2-D2’s chattering from Star Wars. The selectable themes are dubbed “performers”, and they can be reprogrammed easily using CircuitPython. This is a neat way to give your little desktop assistant some personality, and a fun way to break up the monotony of soldering up all those tiny SMD components on your next prototype.

If even after all this you still need more than just a cute little robotic voice beeping at you to convince you to get a fume extractor for your bench, then maybe some hands-on results could give you that little push you need. And if you’re already convinced and want to build your own, there is no shortage of DIY solutions we’ve seen around here at Hackaday. Check out this one in action after the break!

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