One of the most popular methods of homebrew PCB fabrication is the toner transfer process. Compared to UV-sensitive films and CNC mills, the toner transfer process is fantastically simple and only requires a laser printer. Being simple doesn’t mean it’s easy, though, and successful toner transfer depends on melting the toner to transfer it from a piece of paper to a copper clad board.
This is heatless toner transfer for PCB fabrication. Instead of using a clothes iron or laminator to transfer toner from a paper to board, [simpletronic] is doing it chemically using acetone and alcohol.
Acetone usually dissolves laser printer toner, and while this is useful for transferring a PCB from paper to board, it alone is insufficient. By using a mixture of eight parts alcohol to three parts acetone, [simpletronic] can make the toner on a piece of paper stick, but not enough to dissolve the toner or make it blur.
From there, it’s a simple matter of putting a piece of paper down on copper clad board. After waiting a few minutes, the paper peels off revealing perfectly transferred board art. All the usual etching techniques can be used to remove copper and fabricate a PCB.
This is an entirely novel method of PCB fabrication, but it’s not exactly original. A few days ago, we saw a very similar method of transferring laser printed graphics to cloth, wood, and metal. While these are probably independent discoveries, it is great evidence there are still new techniques and new ways of doing things left to be discovered.
Thanks [fridgefire] for the tip.
While OSHPark, Seeed Studio, and DirtyPCB have taken most of the fun and urgency out of making your own circuit boards at home, there are still a few niche cases and weird people who like to go it alone. For them, [Jarzębski] has created the ultimate homebrew PCB manufacturing solution (.pl, here’s the Google translatrix).
[Jarzębski] is using UV-sensitive photomasks for his PCBs, but he’s not doing something simple like a blacklight to develop his boards. He’s using a 30 Watt UV LED for exposing his boards. This, of course, generates a lot of heat and to mitigate that he’s added a Peltier cooler, temperature sensor, and a fan to cool off this retina-burning LED. 30 Watts will get the job done, considering [Jarzębski] was using a quartet of 4.5W LEDs before this build.
Developing a PCB is only one part of the equation; you need to etch it, too. For this, [Jarzębski] is using a small 1.6 Liter aquarium and four aquarium heaters for dunking 120mm x 120mm PCBs in the tank. There’s no mention of what chemistry [Jarzębski] is using – ferric chloride, cupric chloride, or otherwise – but the heaters and aerator should make etching go very smoothly.
There’s a video (English) going over the rest of the project below.
Continue reading “The Ultimate Tool For Homebrew PCB Manufacturing”
The Intel Edison is a neat piece of hardware, but the connector for the Edison is extremely intimidating and the Mini breakout board is incompatible with breadboards. What’s [Federico], a builder of Internet of Things to do? Etch their own breakout board.
The Mini Breakout board for the Intel Edison is the official ‘minimal’ offering for getting the Edison up and running with a mess of jumper wires and LEDs. While this breakout board handles the USB to UART bridge, power regulation, and exposes all the pins on the Edison connector, it is terrible for prototyping. It’s a 4×14 array of holes on a 0.1″ grid that are hidden underneath the Edison.
[Federico] handled this problem with a copper clad board and a little bit of ferric chloride. He jumped into Eagle and created a breakout board to turn the 4×14 pin grid into a more sensible breadboard-friendly layout.
The breadboard-friendly adapter doesn’t have level shifters, but by using the mini-breakout board between the Edison and the breadboard adapter [Federico] still has the UART to USB hardware and a battery charging circuit. Still, there’s room for improvement and we can’t wait to see what he comes up with next.
The toner transfer process of producing PCBs has evolved tremendously over the last few years. It started out by printing PCB layouts onto magazines with a laser printer, then some clever people figured out that glossy inkjet photo paper would work just as well. Now there’s a new substrate for you – packing tape – and it seems to work pretty well.
[David] was designing a cheap board for a robot kit for a workshop and needed 100 tiny PCBs. They were simple boards, and perfectly suited for home PCB manufacturing. He started off by printing directly onto glossy magazine paper, but this wasn’t an ideal solution. During one run, some of the toner landed on the packaging tape he was using to secure the boards. A bit of serendipity came into play and [David] discovered packaging tape is usable in the toner transfer process.
The technique is simple enough: put some packaging tape on a piece of paper, print a board layout (reversed!) on a laser printer, and go through the usual clothes iron/laminator/etching process. [David] is actually using a hair straightener for transferring the toner over to the copper clad board – interesting, and in a pinch you can use the same tool for reflowing SMD components.
There may be nothing new under the sun when it comes to etching PCBs with UV light, but [Heliosoph] has brought finer control to a used face tanner he bought that now exposes his boards in ~50 seconds.
The original system allowed for exposure times from 1-99 minutes to be programmed in 1-minute increments. [Heliosoph] though it would be perfect as-is, but the lamp is so powerful that even one minute of exposure was too much. He hoped to find TTL when he opened the thing and was pleasantly surprised to discover a COP410L microcontroller and an MM5484 display driver. Unfortunately, the COP410L’s clock range is too small and he didn’t want to overclock it.
[Heliosoph] built a new board based on the ATMega328P with a salvaged 16×2 LCD, which he was able to easily integrate using the library that ships with the Arduino IDE. He then replaced the BT136 triac lamp switch with a solid state relay, conveniently isolating the electronics from mains power. He re-purposed the unit’s push buttons using the M2tklib, which supports a plethora of common menu functions.
If you need some help with the whole UV PCB etching process, you can’t go wrong with this tutorial from [CNLohr].
[Quinn Dunki]’s Veronica, a homebrew computer based on the 6502 CPU, is coming along quite nicely. She’s just finished the input board that gives Veronica inputs for a keyboard and two old Nintendo gamepads. [Quinn] is building this computer all by her lonesome, including etching all the PCBs. She’s gotten very, very good at etching her own boards, but this input board did inspire a few facepalming moments.
In an earlier post, [Quinn] went over her PCB etching capabilities. As demonstrated by the pic above, she’s able to print 16 mil traces with 5 mil separation. This is just about as good as you can get with homebrew PCBs, but it’s not without its problems.
[Quinn] is using a photographic process for her boards where two copies of a mask is printed on an acetate sheet, doubled up, and laid down on a pre-sensitized copper board. The requirement for two layers of toner was found by experience – with only one layer of toner blocking UV light, [Quinn] got some terrible pitting on her traces and ground planes.
Two photographic masks means the masks must be precisely aligned. This example shows what happens when the acetate sheets are ever so slightly misaligned. With a 5 mil gap between traces, [Quinn] needs to align the masks to within ±2.5 mils; difficult to do by eye, and very hard once you factor in flexing and clamping them down to the copper board.
Even when this process goes perfectly, [Quinn] is pushing the limits of a laser printer. When printing at 600 dpi, the pixels of the print are about 1.5 mils. While GIMP, printer drivers, and the printer itself have some fancy software to help with the interpolation, [Quinn] is still seeing ‘bumps’ on the edges of perfectly aligned parts. This is one of those things that really makes you step back and realize how amazing fabbing PCBs at home actually is.
With most of the hardware for Veronica out of the way, it’s just about time for [Quinn] to start programming her baby. We’re not expecting a full-blown operating system and compiler, but those NES gamepads are probably crying out for some use.
There are a ton of benefits for etching your own circuit boards at home, chief among them the ability to design a circuit in the morning and have a prototype in your hand by lunch. There’s always the question of how to etch the board, but [NurdRage] over on Youtube has all the chemistry covered on ten different etchant solutions for DIY PCB manufacturing.
The peroxide-based methods use simple over-the-counter Hydrogen Peroxide to remove all the copper on a PCB. By combining H2O2 with either Hydrochloric (muriatic) acid or Sulfuric acid, you’ll get a relatively easy to acquire and somewhat safe etching solution.
Historically, the favorite etchant for the home PCB manufacturer has been Ferric Chloride and is still surprisingly available at a few Radio Shacks around the US. Another chloride etchant – Copper Chloride – is one of the most reusable etchants available, able to be regenerated by simply bubbling air through the solution. You can actually make Copper Chloride etchant by reducing down the products of an H2O2 + HCl etchant, making this a very good etchant for PCB pros.
In the ‘miscellaneous’ category, [NurdRage] goes over some alternative etchants such as Bleach and HCl, Nitric acid, and potassium nitrate and HCl; the potassium nitrate etchant is fairly similar to aqua regia, so if you’ve ever wanted a gold PCB, this is the way to go.
Balancing the ease of production and safety of all these etchants, we’ll stick with our Hydrogen Peroxide and HCl etchant for now, at least until we move up to CuCl for the best etching machine we’ve ever seen.
Continue reading “10 ways to etch PCBs at home”