Spare SMD Storage, With Stacking SMT Tape Reels

October 5, 2020 by Donald Papp 10 Comments

[Kadah]’s solution for storing short tapes of SMT parts is as attractive as it is clever. The small 3D-printed “tape reels” can double as dispensers, and stack nicely onto each other thanks to the sockets for magnets. The units come in a few different sizes, but are designed to stack in a consistent way.

We love the little touches such as recessed areas for labels, and the fact that the parts can print without supports (there are a couple of unsupported bridges, but they should work out fine.) Also, the outer dimensions of the units are not an accident. They have been specifically chosen to nestle snugly into the kind of part drawers that are a nearly ubiquitous feature of every hardware hacker’s work bench.

STLs are provided for handy download but [Kadah] also provides the original Fusion 360 design file, with all sizes defined as easily-customized parameters. In addition, [Kadah] thoughtfully provided each model in STEP format as well, making it easy to import and modify in almost any 3D CAD program.

Providing 3D models in STEP format alongside STLs is nice to see, because it gives more options to people if things need some tweaking, because editing the STL file can be done if needed, but isn’t optimal. Thankfully the ability to export STEP files is still open to hobbyists using Fusion 360, since Autodesk decided to leave that feature available to personal use licenses.

Fail Of The Week: How Not To Re-Reflow

October 10, 2019 by Dan Maloney 30 Comments

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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Control The Suck With This Manual Vacuum Pick-And-Place Tool

August 14, 2019 by Dan Maloney 10 Comments

The tapes that surface-mount devices come in may be optimized for automated pick and place, but woe betide those who try to dig components out manually. No matter what size package, the well on the tape seems to be just a wee bit too small to allow tweezers to grip it, so you end up picking the thing up edgewise or worse, pinching too tight and launching the tiny thing into The Void. We hope you ordered extra.

Such circumstances are why vacuum handlers were invented, but useful as they are for picking and placing SMDs, they aren’t perfect. [Steve Gardener]’s sub-optimal experience with such tools led him to build this custom vacuum pick-and-place tool. It’s based on an off-the-shelf Weller unit, of which only the handpiece remains. A bigger, more powerful vacuum pump is joined in a custom enclosure by a PCB with a PIC18F13K22 microcontroller, a power supply, a solenoid to control the vacuum, and a relay to switch the pump. A footswitch starts the pump and closes the vacuum vent; letting off the pedal opens the vent to drop the part, while the pump keeps running for a variable time. This lets him rapidly work through a series of parts without having to build vacuum back up between picks. The video below shows the build and the tool in action.

We love the idea of this tool, and the polished look is pretty slick too. If manual pick-and-place isn’t for you, though, maybe converting a 3D-printer into an automated PnP is something to check out.

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Acrylic Stencils Help With Component Placement For SMD Assembly

July 16, 2018 by Dan Maloney 12 Comments

Surface mount is where the action is in the world of DIY PCBs, and deservedly so. SMDs are so much smaller than through-hole components, and fewer holes to drill make surface-mount PCBs easier to manufacture. Reflow soldering is even a snap now thanks to DIY ovens and solder stencils you can get when you order your boards.

So what’s the point of adding another stencil to the surface-mount process? These component placement stencils are [James Bowman]’s solution for speeding up assembly of boards in production runs too small to justify a pick and place robot. [James] finds that placing small components like discrete resistors and caps easy, but struggles with the placement of the larger components, like QFN packaged microcontrollers. Getting such packages lined up exactly is hard when the leads are underneath, and he found repositioning led to smeared solder paste. His acrylic stencils, which are laser-cut from SVGs derived directly from the Eagle files with a script he provides, sandwich the prepped board and let him just drop the big packages into their holes. The acrylic pops off after placement, leaving the components stuck to the solder paste and ready for their trip to the Easy Bake.

[James] claims it really speeds up hand placement in his biggish runs, and it’s a whole lot cheaper than a dedicated robot. But as slick as we think this idea is, a DIY pick and place is still really sweet.

Simple Mechanism Gives Support For SMT Assembly

April 10, 2018 by Dan Maloney 15 Comments

With the fine work needed for surface-mount technology, most of the job entails overcoming the limits of the human body. Eyes more than a couple of decades old need help to see what’s going on, and fingers that are fine for manipulating relatively large objects need mechanical assistance to grasp tiny SMT components. But where it can really fall apart is when you get the shakes, those involuntary tiny muscle movements that we rarely notice in the real world, but wreak havoc as we try to place components on a PCB.

To fight the shakes, you can do one of two things: remove the human, or improve the human. Unable to justify a pick and place robot for the former, [Tom] opted to build a quick hand support for surface-mount work, and the results are impressive considering it’s built entirely of scrap. It’s just a three-piece arm with standard butt hinges for joints; mounted so the hinge pins are perpendicular to the work surface and fitted with a horizontal hand rest, it constrains movement to a plane above the PCB. A hole in the hand rest for a small vacuum tip allows [Tom] to pick up a part and place it on the board — he reports that the tackiness of the solder paste is enough to remove the SMD from the tip. The video below shows it in action with decent results, but we wonder if an acrylic hand rest might provide better visibility.

Not ready for your own pick and place? That’s understandable; not every shop needs that scale of production. But we think this is a great idea for making SMT approachable to a wider audience.

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Make A Better, Spring-Loaded SMT Tape Strip Holder

January 19, 2018 by Donald Papp 6 Comments

Every so often, a project is worth some extra work to see if the idea can go any further. [JohnSL] has been busy doing exactly that with his spring-loaded SMT tape holder project. Having done the original with 3D printing, he has been working on designing for injection molding. This isn’t a motorized feeder, it’s still a manual tool but it is an improvement over the usual workshop expedient method of just sticking segments of tape down to the desktop. Tape is fed into the holders from one end and spring tension holds the tape firm while a small slot allows the cover tape to be guided backward after peeling. As anyone who has used cut segments of tape to manually deal with SMT parts knows, small vibrations — like those that come from peeling off the clear cover — can cause the smaller components to jump around and out of their pockets, and any length of peeled cover gets awkward quickly.

The design allows for multiple holders to mount side-by-side.

In [JohnSL]’s design, all SMT tapes sit at an even height regardless of size or tape thickness. A central support pushes up from the bottom with tension coming from a spring pulling sideways; the central support is forced upward by cams and presses against the bottom surface of the tape. As a result, the SMT tape gets supported from below with even tension and the whole assembly maintains a narrow profile suitable for stacking multiple holders side by side. The CAD files are available online along with a McMaster-Carr part number for the specific spring he used.

After working out the kinks on 3D printed prototypes, [JohnSL] decided to see if it would be feasible to design an injection molded version and made a video outlining the process, embedded below.

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Improved Perfboard For Surface Mount Parts

January 9, 2018 by Brian Benchoff 26 Comments

Look through the last two decades of electronics project built on perfboard, and you’ll notice a trend. Perfboard is designed for through-hole parts, but ever more frequently, the parts we need are only available as surface mount devices. What does this mean for the future of all those protoboard, veroboard, and tagboard designs? It’s not good, but fortunately, there may be an answer. It’s perfboard designed for mounting SOICs, SOTs, and other surface mount devices.

Perfboard is an extremely simple concept. Most through-hole electronic components are built around 0.1″ or 2.54 mm spacing between pins. Yes, there are exceptions, but you can always bend the middle pin of a transistor and put it in a hole. SMT devices are different. You can’t really bend the pins, and the pin pitch is too small for the 0.1″ holes in traditional perfboard.

[electronic_eel] is changing that game up with his own design for perfboard. This perfboard has the traditional 0.1″ holes, but there are SMD pads sprinkled about between these holes. The result is being able to solder SOIC, SOT23-6, SOT23 and SOT363 devices directly to a board alongside 0603 and 0805 devices. Connect everything with a few beads of solder and you have a functional circuit made out of surface mount devices on something that’s still compatible with the old protoboard designs.

This isn’t the first time we’ve seen a new type of protoboard make it into production. A few years ago, Perf+, a bizarre ‘bus-based’ protoboard solution came onto the scene, although that wasn’t really designed for SMD parts. While [electronic_eel] doesn’t have any plans to sell his protoboard, the files are available, and you can easily design your own small piece of perfboard.