----------------------------------------------------------------------------- Making your own circuit board A step-by-step guide by Jeff Noxon Version 0.1 - 2000-08-06 ----------------------------------------------------------------------------- PARTS & TOOLS YOU WILL NEED: Computer w/ PostScript(tm) Laser Printer Laser Overhead Transparency Film (5-10 sheets at most) Clothes Iron & Ironing board - You can get the transparency film at any office supply store. Buy a small package of the generic stuff. - If you don't have a PostScript laser printer, you can download Ghostscript from the Internet for free. You could also try using the PDF file of the circuit board layout, but I don't recommend it because Adobe Acrobat seems to have problems getting the scale right. It needs to be perfect! Dremel Tool - This will be used to make the holes in the board Dremel Drill Press Attachment - This is fairly inexpensive and works well. Worth the investment! Trust me, you do not want to hand-hold the drill! Drill Bits, #64 or #70, carbide preferred. - These are available from a hobby shop, serious electronic parts store, or Micro Mark. Buy several, or buy a set. If you can find ones that are wider at the end that goes in the drill, get them. Otherwise you'll have to use some electrical tape to make them thick enough to go in the tool. The bits should cost about $1 each and they break easily, so get extras. Copper-clad circuit boards - These are available from Radio Shack. Get the smallish boards with copper cladding on one side. They usually come 2 or 3 to a pack. Make sure you get boards that aren't pre-drilled! Ferric Chloride ("Etchant") - You can get this stuff at Radio Shack too. Get the small bottle. Silicone sealant spray - This is optional, but it will protect the device from oxidation when you're done. You can get this at a serious electronics store. Sharpie brand fine-tip permanent marker A timer or a watch A small plastic (i.e. leftover) container - This should be large enough to fit a few of your circuit boards and about 1 to 1.5 cups of liquid. Make sure it has a tight fitting, waterproof lid. And never use it for food again! DO NOT USE METAL. Magnifying glass ----------------------------------------------------------------------------- PROCEDURE 1. Print out the circuit board layout (filename: iso_b1.ps) onto a sheet of paper. Verify that the scale is correct. 2. Set the laser printer to its darkest (or least economical) setting. If the printer allows you to specify transparency film as a paper type, do so. 3. Print out the board layout again, this time on transparency film. 4. Empty all water from the clothes iron! 5. Heat up the clothes iron. I suggest somewhere in the high heat range, maybe 8 on a scale of 10. This part takes trial, error, and patience. 6. While the iron is heating up, fetch one of your copper clad boards. Clean it with soap and water. If any tarnish is showing, lightly scrub it with a sponge until it looks clean. Chore Boy makes some scrubbing pads that work very well. Dry the board completely on a clean towel. Take care not to touch the copper. 7. Line up the transparency on the copper, toner side down. I suggest you find something heavy (and heat resistant!) to hold the edges of the transparency film in place. 8. For 10-15 minutes, iron the transparency film onto the copper clad board. Keep an eye on the plastic. Transparency film is designed to withstand high heat, but maybe your iron gets a lot hotter than mine. Do not let the transparency film get soft! Use firm but not overbearing pressure with the iron. When the time is up, remove the iron but DO NOT TOUCH the transparency film or the board for at least another 5-10 minutes. If you have not guessed already, this is going to re-fuse the toner to the copper clad board. I know, this will seem like forever, but if you rush it, it will not work out as well. Relax and watch TV while you iron. :-) 9. Run some cold water. Carefully move the transparency film WITH the board over to your sink. Do not try to peel them apart yet. Put it under the cold water until the whole thing feels cool. Carefully and slowly, peel the film away from the board. Most of the toner should remain on the board. If not, clean the board with a solvent (fingernail polish remover works well) and repeat the process with the iron until you get the hang of this. 10. Pretty cool, huh? You just made an etch-resistant mask on the copper. 11. Dry the circuit board and inspect it carefully. Make sure the toner covers the traces completely. If it doesn't, use the Sharpie to darken in the light spots. 12. It's showtime! Heat up some water. Not to boiling or steaming, just very hot. You may also want to put on some rubber gloves. Add a solution of 50% hot water and 50% ferric chloride to the plastic container. NOTE 1: Ferric Chloride is very nasty stuff. Do not get it on anything metal. If you do, wash it off quickly and completely in cold water. It will stain your clothes. NOTE 2: Radio Shack for some reason says not to use hot water with their Ferric Chloride. They're full of shit. Without heat, the etching will take a really long time and it won't be nearly as accurate. Just don't breathe vapors, OK? After you add the solution to the container, put your circuit board in there. Put the lid on. 13. Agitate the container for 5 minutes. 14. Open the container and remove the board with something non-metallic. 15. Rinse the board under cold water. Keep the water running long enough to flush the chemicals fully from your sink. If the board is fully etched, go on to the next step. If you aren't sure whether the etching is complete, check the resistance of the board with a volt/ohm-meter. If it has less than infinite resistance between two areas that do *not* contain traces, it needs more etch time. Etch the board in the Ferric Chloride solution for 1 or 1.5 minute intervals until it is fully etched. Remember to agitate. 16. What you should have now is a bare board with black traces on it. Rinse the board again. You can discard the etching solution, or save it for use again. 17. Use a solvent (such as nail polish remover) to clean the board. This will remove the toner and "permanent" ink. This is your circuit board in all its glory! Rinse and dry the board, and remember to avoid touching the copper. 18. If your resist mask was good, the traces on your board will be solid and without breaks. If there are any minor visible problems you can fix them using a conductive pen. CircuitWorks makes these pens, and you can probably find them at Radio Shack. It will probably be cheaper, however, to just make another board. Depending on the nature of your problem, you could also fix it with a solder bridge or small bits of wire. It's up to you. 19. It's time to drill holes. Put one of those tiny bits in your dremel tool. If they don't fit, build them up at the base with some electrical tape. Set your tool to its slowest setting and make a few test drills in one of your extra circuit boards before you do the "real thing." Remember, take it nice and slow, and hold the board steady with your hand while you drill. 20. Assemble your project! 21. Once everything works, remove the solder flux if you like. (Radio Shack sells something for this.) Then spray the sealant on the circuit side of your board. This will protect the copper from oxidation. ----------------------------------------------------------------------------- Please send comments and suggestions to Copyright 2000 Jefferson Noxon. Redistribute freely in un-modified form. This notice must remain attached.