You don’t think much about the power company until you flip the lights on and they don’t come on. The same can be said of soldering flux. You don’t think much about it, usually, until you try soldering without it. Flux has a cleaning action on metal surfaces that allows for a proper solder joint. The problem is, do you have any idea what’s in the flux you are using? We don’t either. [Catsndogs] has a recipe to make your own flux and then you’ll know.
At the heart of rosin flux is basically tree sap. If you live near pine trees, you can source it naturally. If not, you can find it at music instrument stores. Stringed instruments use rosin, so it is readily available. If you do source it yourself, [Catsndogs] reports that it doesn’t matter if it is old or clean. You do want to pick out as much tree bark and dead ants as you can, though. You essentially dissolve it in alcohol (at least 80% isopropyl or ethanol). Then filter it through filter paper or a coffee filter.
You can adjust the viscosity by allowing the alcohol to evaporate to make the mixture thicker or by adding more alcohol to make it thinner. Thicker flux is good for tacking down SMD parts. As you might expect, this isn’t “no clean” flux. Also, the flux is very flammable, so be careful.
This isn’t the first time we’ve heard of this recipe. Or even the second time. But it is a good reminder that you can make your own free of whatever wacky chemicals are in the commercial preparations.
Science today seems to be dominated by big budgets and exotics supplies and materials, the likes of which the home gamer has trouble procuring. But back in the day, science was once done very much by the seats of the pants, using whatever was available for the job. And as it turns out, some of the materials the old-timers used are actually still pretty useful.
An example of this is a homemade version of “Faraday Wax”, which [ChristofferB] is using for his high vacuum experiments. As you can imagine, getting a tight seal on fittings is critical to maintaining a vacuum, a job that’s usually left to expensive synthetic epoxy compounds. Realizing that a lot of scientific progress was made well before these compounds were commercially available, [ChristofferB] trolled through old scientific literature to find out how it used to be done.
This led to a recipe for “Faraday Wax”, first described by the great scientist himself in 1827. The ingredients seem a little archaic, but are actually pretty easy to source. Beeswax is easy to come by; the primary ingredient, “colophony”, is really just rosin, pretty much the same kind used as solder flux; and “Venetian red” is a natural pigment made from clay and iron oxide that can be had from art suppliers. Melted and blended together, [ChristofferB] poured it out onto wax paper to make thin strips that are easily melted onto joints in vacuum systems, and reports are that the stuff works well, even down to 10-7 mbar.
We love this one — it’s the perfect example of the hacker credo, which has been driving progress for centuries. It also reminds us of some of the work by [Simplifier], who looks for similar old-time recipes to push his work in DIY semiconductors and backyard inductors forward.
[David Gustafik] dropped us the tip on this one. Thanks!
Solder is the conductive metal glue that one uses to stick components together. If you get the component and the PCB hot enough, and melt a little solder in the joint, it will stay put and conduct reliably. But it’s far from simple.
There are many different solder alloys, and even the tip of the soldering iron itself is a multi-material masterpiece. In this article, we’ll take a look at the metallurgy behind soldering, and you’ll see why soldering tip maintenance, and regular replacement, is a good idea. Naturally, we’ll also touch upon the role that lead plays in solder alloys, and what the effect is of replacing it with other metals when going lead-free. What are you soldering with? Continue reading “The Fascinating World Of Solder Alloys And Metallurgy”→
Often it feels as if soldering is deemed to be more of an art form than something that’s underpinned by the cold, hard reality of physics and chemistry. From organic chemistry with rosin, to the material properties of fragile gold bond wires and silicon dies inside IC packages and the effects of thermal stress on the different parts of an IC package, it’s a complicated topic that deserves a lot more attention than it usually gets.
A casual inquiry around one’s friends, acquaintances, colleagues and perfect strangers on the internet usually reveals the same pattern: people have picked up a soldering iron at some point, and either figured out what seemed to work through trial and error, or learned from someone else who has learned what seemed to work through trial and error. Can we say something scientific about soldering?
For most of the history of industrial electronics, solder has been pretty boring. Mix some lead with a little tin, figure out how to wrap it around a thread of rosin, and that’s pretty much it. Sure, flux formulations changed a bit, the ratio of lead to tin was tweaked for certain applications, and sometimes manufacturers would add something exotic like a little silver. But solder was pretty mundane stuff.
Then in 2003, the dull gray world of solder got turned on its head when the European Union adopted a directive called Restriction of Hazardous Substances, or RoHS. We’ve all seen the little RoHS logos on electronics gear, and while the directive covers ten substances including mercury, cadmium, and hexavalent chromium, it has been most commonly associated with lead solder. RoHS, intended in part to reduce the toxicity of an electronic waste stream that amounts to something like 50 million tons a year worldwide, marked the end of the 60:40 alloy’s reign as the king of electrical connections, at least for any products intended for the European market, when it went into effect in 2006.
Did you ever stop to think how unlikely the discovery of soldering is? It’s hard to imagine what sequence of events led to it; after all, metals heated to just the right temperature while applying an alloy of lead and tin in the right proportions in the presence of a proper fluxing agent doesn’t seem like something that would happen by accident.
Luckily, [Chris] at Clickspring is currently in the business of recreating the tools and technologies that would have been used in ancient times, and he’s made a wonderful video on precision soft soldering the old-fashioned way. The video below is part of a side series he’s been working on while he builds a replica of the Antikythera mechanism, that curious analog astronomical computer of antiquity. Many parts in the mechanism were soldered, and [Chris] explores plausible methods using tools and materials known to have been available at the time the mechanism was constructed (reported by different historians as any time between 205 BC and 70 BC or so). His irons are forged copper blocks, his heat source is a charcoal fire, and his solder is a 60:40 mix of lead and tin, just as we use today. He vividly demonstrates how important both surface prep and flux are, and shows both active and passive fluxes. He settled on rosin for the final joints, which turned out silky smooth and perfect; we suspect it took quite a bit of practice to get the technique down, but as always, [Chris] makes it look easy.
I’ve been soldering for a long time, and I take pride in my abilities. I won’t say that I’m the best solder-slinger around, but I’m pretty good at this essential shop skill — at least for through-hole and “traditional” soldering; I haven’t had much practice at SMD stuff yet. I’m confident that I could make a good, strong, stable joint that’s both electrically and mechanically sound in just about any kind of wire or conductor.
But like some many of us, I learned soldering as a practical skill; put solder and iron together, observe results, repeat the stuff that works and avoid the stuff that doesn’t. Seems like adding a little inside information might help me improve my skills, so I set about learning what’s going on mechanically and chemically inside a solder joint.