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Do-It-Yourself PCB Etching (photoresist method)
So the Sharpie method wasn't cuttin' it fer ya, eh? That's perfectly understandable, I'm not fond of it either. Let's try the photoresist method instead, yeah?

This method of making circuit boards is a bit more involved, but will definitely yield results FAR superior to manually adding resist to the board. You'll need the following:

1.) A presensitised copper-clad board
2.) Your circuit design on a transparency (or film)
3.) An exposure lamp (a couple of "daylight" flourescent bulbs should do)
4.) Developing solution
5.) Etching solution (ferric chloride)

First of all, you'll need to get your hands on some PRESENSITISED copper-clad boards. These are basically the same copper boards used in the other tutorial, but they have a light-sensitive layer covering the surface, which usually appears green-ish. (You can get them from Mouser and Parts Express, for example). I suggest keeping it in it's black protective bag until it comes time to use it, because premature exposure to sunlight can mess it up. Anyhow. Moving on.



I typically use a combination of Adobe Illustrator and a few other programs to create my circuit layouts, but you can just as easily use Illustrator by itself. (Or even Microsoft Paint if that's your thing). Just keep your design black and white. No point in going CMYKrazy , because the copper won't care. Copper is a cruel beast that doesn't give a red hot shit. It's black or white, on or off, up or down. If you're still reading, I applaud you. Let's continue.



Now you'll need to print your design out on a transparency. This is typically done via a laser printer, but I'm pretty sure the inkjet transparencies will work just as well. When in doubt, just photocopy your design onto a transparency at Kinkos. Myself, I'm lucky enough to have friends at work that printed my design out on film for me. The difference? It's a little more crisp and dark, like Hershey's. Don't hate me, a laser transparency will work just fine.



Now comes a very important part. Once you're ready to expose the board, peel the protective backing off the face of the board, place the transparency on top of the board and expose under UV lamps for a minute or so. (I cooked mine for exactly 1 minute 45 seconds). I have access to a unit specifically designed for this at work, but I hear you can just use a couple of "daylight" flourescent bulbs to expose the plate. I'll probably build one for home use when I find the time. Anyhow...

What's happening here? The presensitized boards are covered with a thin layer of light-sensitive emulsion stuff. When exposed to UV light, it becomes somewhat soft and is removed with developer. The areas of your board that were NOT exposed will remain. This is your resist. So instead of manually adding resist to the board like the sharpie method, the board is already completely covered in a resist, and we're removing what we DON'T want to end up as copper on the board. ...Moving on.



After exposing the board, you'll want to immediately develop it. Completely emmerse the board face-up in the developer and let it sit there until the exposed areas of the UV emulsion are eaten away by the solution. Developing time can be affected by how long the board was exposed. For me, it only took about a minute. Oh, and I hear this stuff isn't good for you, so don't go splashing around in it. You've been warned.



Afterward, pull the board out of the solution and quickly rinse under water then wipe dry. The unexposed area (your circuit design) should be clearly visible, and everything else will be exposed copper. At this point, your board is ready to be etched.



NOTE: I'm no longer using that stupid little etching tray from the other tutorial. I've since built a bubble tank that agitates the solution for me. (For info on how to make one, click here). It's bathtime!



Isn't that awesome? A tank full of bubbling, copper-murdering acid! I'm officially a level 1 mad scientist.



The etching took roughly 20 minutes, which is about normal. After rinsing the board under water and patting it dry, we get to see the final results!



I must say I'm extremely pleased with this photoresist method. The resulting traces are so clean and fine, it blew my mind. (On my first attempt, even!) This is how I'll be doing my boards from now on, no question. You should too.



...

SPONTANEOUS CORGI!




 
 

 
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