Solder Bridges Aid Desoldering

As our own Elliot Williams laid out, many people think that soldering is a key skill for electronics, but we don’t as often think about desoldering. Even if you are perfect in your technique, there’s always the chance you’ll put in a bad part or have a part fail later and it will need replacement. [Robert] has a short video showing his method for removing through-hole components and you can see it below.

This isn’t the first time we’ve seen it, of course. In fact, it is very much like using hot air, although it doesn’t require hot air, just extra solder and a regular iron. Of course, if we knew that connector was bad, we’d have been tempted to cut each pin apart and remove them one at a time. Heating a joint and then slamming your hand on the bench can work wonders.

We always think desoldering pumps are a good idea, but the electric ones tend to be anemic. The ones with the springs are usually better, but still have limitations. In the end, we’ll stick with using hot air, but if all you have is an iron, this method is worth checking out. You might also be interested in the needle method.

Continue reading “Solder Bridges Aid Desoldering”

Modified 3D-Printer Solders Through-Hole Components

Surface-mount technology has been a fantastic force multiplier for electronics in general and for hobbyists in particular. But sometimes you’ve got no choice but to use through-hole components, meaning that even if you can take advantage of SMDs for most of the design, you still might need to spend a little time with soldering iron in hand. Or not, if you’ve got a spare 3D printer lying around.

All we’ve got here is a fairly brief video from [hydrosys4], so there aren’t a lot of build details. But it’s pretty clear what’s going on here. Starting with what looks like a Longer LK4 printer, [hydrosys4] added a bracket to hold a soldering iron, and a guide for solder wire. The solder is handled by a more-or-less standard extruder, which feeds it into the joint once it’s heated by the iron. The secret sauce here is probably the fixturing, with 3D-printed jigs that hold the through-hole connectors in a pins-up orientation on the bed of the printer. With the PCB sitting on top of the connectors, it’s just a matter of teaching the X-Y-Z position of each joint, applying heat, and advancing the solder with the extruder.

The video below shows it in action at high speed; we slowed it down to 25% to get an idea of how it is in reality, and while it might not be fast, it’s precise and it doesn’t get tired. It may not have much application for one-off boards, but if you’re manufacturing small PCB runs, it’s a genius solution. We’ve seen similar solder bots before, but hats off to [hydrosys4] for keeping this one simple.

Continue reading “Modified 3D-Printer Solders Through-Hole Components”

Tape Cutter Makes Short Work Of Through-Hole Resistor Reels

As the world of electronics makes its inexorable movement from through-hole parts to surface-mount, it’s easy to forget about the humble wire-ended resistor. But a stack of them is still a very useful resource for any experimenter, and most of us probably have a bunch of them with their accompanying twin strips of tape. We’re entranced by [Sandeep]’s automated resistor tape cutting machine, which uses a fearsome looking pair of motorized knives to slice the tape into predetermined lengths.

At its heart is an Arduino and a set of stepper drivers, and it uses a PCB that he’s designed as a multipurpose board for motor-based projects. One motor advances the reel of resistors, while the other two operate those knives that simultaneously slice the two tapes. The whole is held in a wooden frame with 3D-printed parts, and control is through a touch screen. This feels more like an industrial machine than a maker project, and as can be seen in the video below, it makes short work of those tapes. Full details can be found on his website, including code.

We’ve not had so many through hole tape cutters, but we’ve seen at least one SMD cutter.

Continue reading “Tape Cutter Makes Short Work Of Through-Hole Resistor Reels”

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.

Continue reading “Fail Of The Week: How Not To Re-Reflow”

Fail Of The Week: How Not To Light Pipe

You’d think that something made out of glass and epoxy would transmit a decent amount of light. Unfortunately for [Jeremy Ruhland], it turns out that FR4 is not great light pipe material, at least in one dimension.

The backstory on this has to do with #badgelife, where it has become popular to reverse mount SMD LEDs on areas of PCBs that are devoid of masking, allowing the light to shine through with a warm, diffuse glow – we’ve even featured a through-PCB word clock that uses a similar technique to wonderful effect. [Jeremy]’s idea was to use 0603 SMD LEDs mounted inside non-plated through-holes to illuminate the interior of the board edgewise. It seems like a great idea, almost like the diffusers used to illuminate flat displays from the edge.

Sadly, the light from [Jeremy]’s LEDs just didn’t make it very far into the FR4 before being absorbed – about 15 mm max. That makes for an underwhelming appearance, but all is certainly not lost. Valuable lessons about PCB design were had, like exactly how to get a fab to understand what you’re trying to do with non-plated holes and why you want to fence the entire edge of the board in vias. But best of all, [Jeremy] explored what’s possible with Oreo construction, and came away with ideas for other uses of the method. That counts as a win in our book.

Components Cut In Half Reveal Their Inner Beauty

We rarely take a moment to consider the beauty of the components we use in electronic designs. Too often they are simply commodities, bought in bulk on reels or in bags, stashed in a drawer until they’re needed, and then unceremoniously soldered to a board. Granted, little scraps of black plastic with silver leads don’t exactly deserve paeans sung to their great beauty – at least not until you cut them in half to reveal the beauty within.

We’ve seen a little of what [Tube Time] has accomplished here; recall this lapped-down surface-mount inductor that [electronupdate] did a while back. The current work is more extensive and probably somewhat easier to accomplish because [TubeTime] focused mainly on larger through-hole components such as resistors and capacitors. It’s not clear how the sections were created, but it is clear that extreme care was taken to lap down the components with enough precision that the inner structures are clearly visible, and indeed, carefully enough that some, most notably the LED, still actually work. For our money, though, the best looking cross-sections are the capacitors, especially the electrolytic, for which [Tube Time] thoughtfully provides both radial and axial sections. The little inductor is pretty cool too. Some of the component diagrams are annotated, too, which makes for fascinating reading.

Honestly, we could look at stuff like this all day.

Thanks to [Stuart Rogers] for the tip.

Why Wait? Just Plate Your Own PCB Vias

[Jan Mrázek] is a pro when it comes to rolling his own PCBs. He can crank out a 6/6 mil double-sided PCB in 45 minutes flat. As a challenge to his prowess, he decided to experiment with plating through-hole PCBs at home, because sometimes you just can’t wait for China to deliver the goods.

The key here is to make a non-conductive surface—the walls of holes drilled in a sheet of copper clad–conductive. While there are some established ways of doing this at home, the chemicals are difficult to source. When his local supplier started stocking colloidal graphite paint, which is used to prevent ESD and fix non-working remote control buttons, he decided to try it.

[Jan] drilled up a board with holes ranging from 0.1mm up to 8mm, polished it, and gave it an acetone bath. He sprayed each side with graphite and cured it at 100 °C for 20 minutes. At this point, wall hole resistance measured 21 Ω. [Jan] wet-sanded away the graphite and set up an electroplating bath. Right away, he could see a layer of copper forming on the holes. After 90 minutes, he polished the board again and separated the vias to prepare for the real test: solder. This time, every hole except the smallest size reported a resistance of 0.1 Ω. But they all sucked solder through the vias, making this experiment a success.

[Jan] concluded that this is a simple and effective process, but is rarely worth the effort. We wonder how the simplicity of this method compares to drilling wells instead of holes, filling them with conductive ink, and then drilling the rest of the via.

Via [Dangerous Prototypes]