KiCAD Plugin Gives Your PCBs That Handmade Look

The first PCBs we built involved a draftsman laying out large pieces of tape. The finished artwork would be photographically reduced to produce the board. This solved a few problems. It was easier to work on the large pieces and any errors were reduced by the scale amount. Boards from this era have a distinct appearance because the tracks are generally curved. But when computer-aided drafting took over, the early packages couldn’t deal with wavy lines making all sorts of angles. So traces started appearing at very common angles like 45 degrees or 90 degrees only. If you use KiCAD, though, there’s no reason to have rectilinear traces. Now there is a plugin to help make your boards appear like old-fashioned circuit boards.

The video by [mitxela] below talks about how we got here and debunks some common myths about PCB design. The plugin produces rounded corners and teardrop-shaped pads. There’s also a second post on the topic with more details. The effect isn’t just ornamental. There are some reasons graceful traces might be better than sharp angles.

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Best Ways To Make PCB Breakaway Tabs, Revealed

Most of us are familiar with the concept of producing PCBs in a panel, and snapping them apart afterwards. V-grooves that go most of the way through a PCB are one way to go about this, but a line of perforations along which to snap a tab is another. But what’s the best size and spacing of holes to use? Sparkfun’s [Nick Poole] spent some $400 on PCBs to get some solid answers by snapping each of them apart, and judging the results.

The nice thing about creating a perforation line (or “mouse bites”) is that drill hits are a very normal thing in PCB production, which makes creating this kind of breakaway tab a very straightforward and flexible method. However, it can be tricky to get results that are just right. Too sturdy, and breaking apart is a hassle. Too weak, and the board may break or twist before its time. On top of that, edges must also break cleanly. We’ve covered panelizing PCBs in this way before, but this is the first time we’ve seen someone seriously look into how to create optimal breakaway tabs.

Placing holes tangent to the board edge (as shown above) isn’t the prettiest, but keeps PCB edges free from protrusions. This is best for boards that are rail-mounted, or have tight enclosures.

Data on designing mouse bites was sparse and a bit inconsistent, so [Nick] decided to figure it out empirically and share the results. The full details are available in Building a Better Mousebite (PDF download) but the essence of the recommendations are: 0.015″ unplated holes, spaced 0.025″ apart (center-to-center), tabs a maximum of 0.118″ wide (so as to be compatible with depanelizing tools), and holes that extend into the corners of the breakaway tab to avoid sharp edges. Holes should be placed slightly differently depending on whether one wishes to optimize the cosmetic appearance versus the physical smoothness of the board edge, but those numbers are the core of the guidelines.

To fine tune, [Nick] suggests increasing the spacing between holes to add strength, or just adding additional tabs. What about thickness of PCB? [Nick] tested boards both 0.8 mm and 1.6 mm thick, and while different amounts of torque were needed to snap the boards apart, things still worked as expected regardless of PCB thickness.

When it comes down to it, the best numbers will ultimately be the ones that your process or fab house can most efficiently handle, but [Nick]’s numbers should not steer anyone wrong, and it’s fantastic to see this kind of work go into refining such a common PCB feature.

How Small Is Too Small?

Not a rhetorical question! This week we consider the most micro microcontroller: the HC32L110. It’s the new title holder of the smallest ARM Cortex M0+ part. But could you actually use it?

MCU is the black thing that’s smaller than the capacitor.

I remember way back, when I first learned to solder surface-mount components. It was fiddly at first, but nowadays I don’t use through-hole components unless someone’s twisting my arm. And I still do my soldering myself — down to 0603 really isn’t all that bad with an iron, and below that, there’s always the heat plate. My heat plate has also gotten me through the two times I’ve actually needed to put down a ball-grid-array part. It wasn’t as bad as I had feared, honestly.

So maybe it’s time for me to take the BGA plunge and design a board or two just to get more familiar with the tech. I probably won’t dive straight into the deep end, like the featured chip here with 0.35 mm ball pitch, but rather stick with something that the cheap PCB services can easily handle. My experience tells me that the best way to learn something is just to test it out.

Now, off to go part shopping in the middle of a chip crisis! Wish me luck.

Backpack Board For OLEDs Boasts Fancy Features

Back when LCD character displays based on the HD44780 controller were the bee’s knees, a way to make them easier to work with came in the form of “backpack” PCBs, which provided an accessible serial interface and superior display handling at the same time. [Barbouri] has updated that idea with a backpack board that mounts to OLED displays using the US2066 display driver, and provides an I2C interface with powerful and convenient high-level functions that make the display simple to use.

On the software side, the backpack uses this I2cCharDisplay driver project which provides functions like cursor control, fading, display shifting, and of course writing characters or strings. While [Barbouri] designed the board specifically to accommodate Newhaven Slim Character OLED displays, it should in theory work with any US2066-based OLED character display. [Barbouri]’s design files for the Slim-OLED Display backpack board are available for download directly from the project page (link is near the bottom), or boards can be purchased directly from OSH Park.

OLED technology is nifty as heck; we’ve seen some neat tricks done by stacking transparent OLED displays, and even seen OLEDs made in the home lab.

Pick and place reels

Pick And Place Hack Chat

Join us on Wednesday, February 9 at noon Pacific for the Pick and Place Hack Chat with Chris Denney!

We in the hacker trade are pretty used to miracles — we make them all the time. But even the most jaded among us has to admit that modern PCB assembly, where components that could easily hide under a grain of sand are handled by robots, borders on witchcraft. The pick and place machines that work these wonders not only have to hit their marks accurately and precisely, but they also do it at blinding speeds and for days on end.

join-hack-chatLuckily, even those of us who design circuits for a living and depend on PCB assembly services to realize those designs can, at least to some degree, abstract the details of the pick and place phase of the process away. But making it “just work” isn’t a trivial task, and learning a little bit about what it takes to do so can make us better designers. Plus, it’s just plain cool to watch a pick and place do its thing. And to dive a little deeper into pick and place, Chris Denney, CTO of Worthington Assembly and co-host of “Pick, Place, Podcast” will stop by the Hack Chat. If you’ve ever wondered about the inner workings of PCB assembly and the role pick and place plays in it, or if you’re looking for tips on how to optimize your layouts for pick and place, this is one you won’t want to miss!

Our Hack Chats are live community events in the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 9 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

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This Parametric Project Box Generator Is Super Easy

When it comes to taking an idea from concept to prototype reality, depending on the type of project, there can be quite a few sub-tasks along the way. Take for example, your latest electronic widget design. You’ve finished the schematic, and the PCB layout is a work of art (if you do say so yourself) but having that kicking around on the desk unprotected with wires dangling is not the end game. Now you’ve got to make an enclosure of some kind, and I don’t know about you, but this is the bit where this scribe struggles a little to get something to fit nice. Even if you’ve got the latest 3D printer dialed in to within a gnat’s whisker of perfection, you’ve still got to come up with the design, and those dimensions need to be really accurate. So, for those of us who are great at the PCB, but suck at the enclosure, [Willem Aandewiel] has been busy making the tool just for you, with his PCB-orientated Yet Another Parametric Projectbox generator (YAPP.)

Defining the PCB mounting points w.r.t. the PCB outline

Without hesitation you can head over to the YAPP GitHub, grab that sweet OpenSCAD code, and get cracking with the demos. Provided for your convenience are a number of examples for enclosing some common items, such as Arduinos and ESP32 modules, so you can use those as a springboard to get your own code in place. YAPP works based off the PCB — by specifying programmatically since this is OpenSCAD — outer dimensions, mounting post locations first. Next you define openings in the six faces of the box, and the tool happily spits out a platter with the base and lid ready to drop into Cura (or your slicer of choice) What could be easier?

End face cutouts

And before you start on non-rectangular designs, this is a rectangular box generator for rectangular PCBs. That is all this is designed for, and as far as we can tell, it does that one job well.

Of course, this is by no means the first enclosure generator to grace these pages, far from it. Here’s one for starters. If you’re here for tips to help make better designs, check this out, and finally 3DHubs also has a nice guide for you. Happy printing!

Planar PCB Coils As An Alternative To Winding Transformers

Those readers who have experimented with winding their own inductors will know that it’s not an easy task, and when those inductors are handling high voltages it can be especially tricky to maintain adequate insulation between layers of windings. [Open Frime TV] has a video addressing this in a novel way, by creating the windings for a switch-mode power supply transformer using stacked PCB coils instead of wire (Russian language; you’ll have to enable YouTube’s subtitle auto-translation).

The video below the break makes for a handy primer on PCB coil construction, reminding the viewer that the turns need all to lie in the same direction as well as the importance of insulation between windings. There’s a discussion of the properties of a PCB coil in relation to the switching frequency, and once the transformer has been assembled, we see it hooked up to a power supply board for a test. What happens next may be familiar to seasoned transformer-winders; nothing works, and the transformer gets hot. In making the PCB he’s left some copper on each board which amounts to a shorted turn — cutting these allows the transformer to work perfectly.

This technique might not be the solution to all transformer woes, but makes for an interesting option if your work takes you in the direction of winding transformers. If PCB coils take your interest, how about a Tesla coil using them?

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