Does anyone still make oneoff circuit boards at home? What methods are being used by hobbyists and where do you get supplies?
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For prototypes I use Press-n-Peel. You laser print the pattern to the PNP then use a clothes iron, or better, a laminating machine to bond it to the copper side of the board. Peel the PNP off the board and etch it. Clean the residue off the board then drill as needed and assemble it.
This from my post on forum.nutsvoltscom Re: Making PCBs at Home Post by Lenp » Wed Sep 02, 2020 3:43 pm
Overhead film is available online and maybe the big box office stores still carry it (who uses overhead projection any more?). PNP Blue film comes with an instruction sheet and it is available online, and from several electronic suppliers that also supply the copper board and etchants. Look online, it’s there as well as several videos showing the process.
This PNP process is great for a not too complex board prototype, but not for quantities. You can have a board from artwork to drill in an hour, correct your mistakes and go again without waiting for a board house turnaround and cost.
I quit doing that when I spilled a gallon bottle of Ferric Chloride in the garage. A friend of mine was recently making some, but the materials are getting hard to get. Besides, ordering small quantities from China is way cheaper than buying the board and chemicals.
The two most common methods I'm aware of are toner transfer and Photosensitive Dry Film. Most people seem to have much better luck with one or the other. I was never able to get toner transfer to work so I use UV film. The supplies for either are available at the usual sources (Mouser, Digikey, Jameco, Amazon, etc). There are a number of articles and videos on the web which describe the process better than I can.
Basically, a UV sensitive film is applied to the PCB, then a transparency is laser printed to overlay it. The areas blocked by the design are those which will be etched away (the print is a negative). The board is dipped in a developer for a couple minutes before it's washed with water. There are a number of echants, but the most common in hobby use is probably ferric chloride. If you use it, please check handling and disposal methods.
You may want to look at PCB prototyping services. Several advertise in Nuts & Volts. For $25-30 you can get 5 boards, 6 mil spacing, drilled, vias, masked, and screened, at your door in a week or so. Honestly, this is probably the way to go, unless you need faster turnaround. Or just wanna (a valid reason in itself!). It is very important to closely check the design rules.
Another possible option is CAD/CAM milling. However, I'm not aware of affordable equipment which has enough precision. I haven't looked in a while, so this may have changed.
In the past, I designed and produced many circuit boards using several methods. By far, the best way to produce circuit boards is to just send the files to a company on the web and have them make them because if your time is worth anything, it is cheaper. However, if you insist on doing it yourself, you can etch them or mill out the unwanted copper, leaving the circuits that you want.
Milling works much better because circuit design software can produce files which can be converted to a program that runs on an othermill home router. It’s likely that other home routers can also be used, but the two people that I’ve seen do it used othermills. These machines are very popular at Makerspaces and school shop classes, etc. Adafruit uses this method to produce all of their one of a kind circuit boards for production testing their products.
This process starts with getting and learning KiCad software, which is free. YouTube has many videos on learning KiCad and Lady Ada often shows how she designs products for Adafruit using KiCad on her “Desk of Lady Ada” YouTube series. Watching this series from the beginning is suggested for anyone learning electronics.
After the KiCad design is done, it’s a matter of contacting the owner of a usable milling machine or sending the files to a board maker. The Hackaday guide: Why Etch A PCB when You Can Mill is suggested reading.
If you are dead set on etching your own boards, you can get several kinds of etchant from Amazon as well as some blank boards. However, a search of the web will likely show several other sources.
Forget any Ferric Chloride based etchant as it’s nasty stuff and works much slower than the better product Ammonium Persulfate, which stays clear enough to see how the process is coming along. You’ll also need a way to time the exposure of the boards and the right kind of lamp. I would suggest making the final board pattern on clear film that can then be taped over the copper clad board and exposed.
The other way to do it is to draw the pattern directly onto the circuit board with a “resist pen,” but it’s very hard to do an accurate job that way.
The transparent film can be printed on certain printers if the correct film stock is used, however getting the size of the image correct to produce the correct size printout might be tricky. We always drew everything 4 times bigger on graph paper and then had a photo shop reduce it 4:1 and print it on clear film.
With the rise of the cheap board manufactures that can provide you a professional board for just a few dollars, this is something of a lost art. I still make my own boards most of the time. The time I have to bring my ideas to life is pretty limited and when I have a good idea I want execute on it right away.
When it comes to making my boards, I would call myself a jack of all trades and master of none. I use a few different methods depending on the complexity of the board and how polished I want the final product to be.
My go to method is photoresistive film and that produces the best output for me. Autodesk Eagle is my tool of choice for laying out my board, printing that output on laser printer transparencies and using a cheap laminator from the local big box store, a cheap light box and photoresistive film from eBay and I can lay down my artwork in about 30 minutes. There are plenty of Internet resources on how to do this online and it works great.
Etching is where the real issues are with making your own boards. It’s messy and dangerous. after all you are dealing with chemicals strong enough to erode metals. I used ferric chloride for years, and it gets the job done, but it’s slow and extremely messy. If you ever spill any, plan on the brown stain left behind to be there forever.
For the past 5 years or so I’ve been using muriatic acid (Hydrochloric Acid) and peroxide for etching my boards in a 50/50 mix. It is super effective and I can run to the local hardware store to grab a gallon, but it is has quite a few real hazards.
First and foremost it gives off chlorine gas so is has to be done outside and away from others and you must always use eye and breathing protection.
Secondly, anything within reach of the fumes made of ferrous metal will rust almost instantly. Both ferric chloride and muriatic acid like to be warm and agitated to work best. I made a simple servo driven device controlled by an arduino to rock the container back and forth and that speeds up the process greatly.
Drilling is next in line and again I have a few methods I use. My primary is just a simple micro drill press and hours of doing my best to hit the center of the pads. Drilling after etching allows you to use the raised copper pad to guide the drill bit.
Lately I have been working on a good technique for using my cheap 3018 CNC router to do this more effortlessly. By etching some alignment marks on two corners of the board I can pin the board down to the waste board on the CNC and let it do all the hard work. So far it is hit and miss but when it works it does a great job.
inally there is making it look good with some solder mask. While it is mostly for aesthetics for me, it does have a real purpose to keep your copper traces from oxidizing. I nearly always use Dynamask film.
Since I usually do photoresist film on my boards, and Dynamask works just like it, I have the tools out and on the bench anyway. Occasionally I use the liquid mask that you can order on Amazon or eBay, and it works, but it just doesn’t product the quality I get out of Dynamask.
So there it is, when you add all the time up and include cleanup afterwords, for a simple board you have used up the better part of a day. Is it worth it? No it’s not, considering the low cost of ordering professional quality boards now.
Will I keep doing it? Absolutely. While it is a ton of work and mess there is just something about it I really enjoy.
After I do my prototype on my hand made board and work out the details, I will get the real deal from a PCB service but the ability to test out an idea on a board the same day the idea hits you is awesome.