When it comes to soldering irons, most of us are likely to be in agreement that there is a level of quality below which we will not descend. To do a decent job requires a decent tool, and when it comes to soldering that means a good quality temperature controlled iron with a decent power level and a quality bit. Anything else just isn’t worth considering.
But what if you look at it from the opposite angle? When it comes to soldering, just how low can you go? In that case probably the ultimate scraping of the soldering barrel comes courtesy of USB soldering irons, taking their juice from a five volt phone charger socket and providing tiny power levels you’d expect to be barely enough to work at all. Surely these are toys, not irons!
Recently I was making an order with your favourite purveyor of electronic bits and pieces from China, and since a USB soldering iron came up on my screen for only £3.69 ($4.76) my curiosity was piqued enough to tack it onto the end of my list of other items.
The postal services of the world are masters of building anticipation, so it was the usual three weeks before a little parcel arrived from the other side of the world. In it alongside the various modules that were the main focus of my order was the subject of this review. An Aneng LT-001 Professional 8 W USB soldering iron, in a clear plastic display carton with a cardboard insert. It’s worth pointing out that very similar irons are available under many different brands, this one can be taken as a representative example.
Unpacking the iron, in front of me was a USB-to-3.5mm power cable, a rather laughable little metal stand, and the iron itself with a protective plastic cap. This weighs only 22 g, or 0.77 oz, and is about 190 mm or 6.5″ long, of which only 45 mm or 1.75″ is the very slim element and bit. The rest is a semi-transparent plastic handle with a single button to activate the iron. Once activated, there is a visible red LED inside the handle to indicate that the iron is on. The packaging claims that the bit can be replaced, however I didn’t find replacement bits for sale and looking at the price for a new iron it’s questionable why you’d want to.
A USB Iron In Use
To test the iron, I plugged the 3.5 mm plug into the socket on its base, and the USB plug on the other end of the cable into my Anker multi-port USB power brick, as it would demand too much power from a PC USB port. I then took a simple electronic kit, an abandoned development product for my kit business, and set to work to put the iron through its paces.
In the first instance, with surface-mount discrete components, this iron was a joy to use. Its meagre power level was not sapped by the heat capacity of the miniscule parts, the tiny bit was just the perfect size, and the iron’s extremely light weight and short length of the element made it very easy to get into the action. In this limited arena this iron was considerably better than some far more expensive irons that possess significant bulk.
Then soldering an SOIC, the lack of power showed itself in being unable to perform in one of the ways a more hefty iron could. Often you will make solder bridges between SOIC pins, and these you will remove with a bit of desoldering braid. Doing this in the normal manner simply sucked the heat away from the USB iron, and required a rescue with a conventional iron. Returning to the other side of the same chip I evolved a technique of soldering each pin with considerably more care, and wicking away the only solder bridge I had with the very end of my braid to minimise heat loss. In this way I was able to desolder with the USB iron, but it was by no means an easy process.
The kit in question has a few 0.1″ pitch through-hole connectors, and the USB iron coped well with these even when the pins were connected to through-plated groundplanes on both sides. It’s possible that it could store enough heat in the pin to allow the solder to attach properly to the through plating before the groundplane sucked too much of it away.
The final component though was a different story, a through-hole BNC socket. Here the main deficiency of the iron showed itself, as the sheer mass of the socket was enough to suck away every joule the little iron could deliver. Eventually I ended up with the USB iron still powered up and soldered fast to the BNC socket, which was not soldered to the board. No doubt if I had waited long enough the whole piece would have come up to solder melting temperature, but probably at the expense of harm to the other components. Thus I rescued it by desoldering the USB iron from the BNC socket with my mains-powered iron, something I can honestly say I’ve never done before.
A Toy, But Not a Joke
So, given that I’ve taken what amounts to a toy and subjected it to a serious review, what’s the verdict?
The first and most obvious conclusion is this: A USB iron is not and never will be a replacement for your conventional iron. With only 8 W on offer there will always come a point at which a soldering job is too much for it, and it will not be able to melt the solder in the face of heat loss.
That said, there are lighter soldering jobs, particularly those involving small surface mount discrete components, in which a USB iron can give a good account of itself, both in terms of heat output and in terms of small size and weight. Yet again it will never be a replacement for a high-end lightweight temperature-controlled iron, but in this arena it can at least do the job rather well.
Would I suggest that you buy one? Given that you can have one of these for relative pennies, I’d say if you are making an order anyway, then yes. But if you are buying one in the expectation that it will deliver the same performance as a mains-powered iron, then definitely not.
My iron will stay in my tool kit, after all there may be times I need to do some especially fiddly surface-mount work when the only power I have us a USB battery bank. It will remain a toy, but after having spent an afternoon using it I can at least say it will not entirely be a joke.