Purchasing the following materials will get you a really good "kit" going, that you can use over and over for any of your small electronics projects. Aron and I have made hundreds of boards (that is no joke) using this technique. Trust us, it is tried and true. It should take you less than 2 boards to start getting them perfect.
From Walmart, K-Mart, or any Grocery Store:
From Radio $hack:
This is the first step, and by FAR the most important. Make sure your schematic diagram is correct. Use your past experience (or someone else's) to figure out if it will work or not when built correctly. Many times, I have spent quite some time making the board itself, and come to find out my original plans were wrong. Sometimes it is easy to modify the board after it's been made, sometimes it's not.
Look at the parts that the schematic calls for - we'll use the above image for an example. Make sure all of the parts are rated for the frequency/current/voltage that they will have to work and put up with. Keep in mind, that things like this are easy to overlook on a schematic. Sometimes you will have to have an EE degree to know exactly what is going on, but if someone else has built the circuit and it works, then you can probably trust it.
Get some paper and a pencil, and start there first. You will be amazed at how many times you will erase and redraw stuff. Using the schematic as a reference, draw the actual copper connections between each part on the paper. Here are a couple of hints from a pro that will save you time:
You will know how big your board will be as soon as your connections are drawn. Make sure to include your mounting holes on the corners, then draw a nice thick box around everything and measure it. Make a box the same size on a corner of the copper board. Now you can begin cutting this (usually square or rectangle) out - by far the easiest tool to use is a Dremel Moto-Tool with a cut-off wheel. If you don't have one, you can C-clamp the board to the edge of the workbench or table and cut it out with a hacksaw or backsaw. Straighten your edges with medium-grit sandpaper on a flat, hard surface.
Keep the paper template you drew the connections on. It will be a great reference later when you do the real work with the Sharpie.
Grab the following four things and head to the kitchen sink:
Turn the water faucet on and start cleaning the board with the steel wool. Don't scrub too hard, but do make sure to get the dirt/oxidation layer off of there. Make sure to only scrub ONE direction (back and forth). No circular motions at all. After you have gotten the copper nice, pink, and shiny, you will get it even more nice pink and shiny with the Scotch-Brite and comet! Dump a small pile of comet directly onto the board, and scrub it (one direction) into the copper with the Scotch pad.
There is a good way to tell if the copper is clean enough. Wash all of the comet off under the faucet, and hold the board to where the copper is facing up. On a clean board, the water will "pool up" and not want to run off. On a dirty board, the board will act like a water-proof surface (like plastic) and cause the water to run off, only leaving a few droplets behind. You want that nice, even layer of water to stay on the board. On the first try, there will be many clean and dirty spots (the corners are hard to get clean). Keep working them with the Scotch-Brite and Comet until the whole board holds water. As soon as it does, you're ready to draw your connections!
Do just as you did when you were making the paper "template", except instead of drawing on paper with a pencil, you will draw on copper with a Sharpie. Modify your original design as you want, but things can get confusing sometimes with complex circuits. Here are a few tips to follow:
Go across the schematic with a highlighter, marking it as you cross-check connections with the PCB. When you think your board is finished, and you know your connections are all there, you're ready to etch!
Drill a tiny hole in each corner of the board, and form a "basket" of magnet wire around it, with a handle you can hold on to while the acid is doing its work. If you have included mounting holes on your board, you can drill these out and use them as I have done. (note - even though the wire in the above picture looks bare it is not. It's #22 from Radio Shack, and has a clear coating)
Put etchant in your container, pull up a chair, mutter a few holy words (God I hope this works), and baptize your circuit board. Keep the board moving, to keep fresh acid going over the exposed copper. This makes things much faster, and keeps the acid from eating underneath the sharpie ink (undercutting). Etch times will vary based on the temperature of the etchant, how old it is, and how many times it has been used.
NOTE: Etchant is some really mean stuff. Don't rub your eyes or nose once you've started working with it, and don't let it get on your clothes or the workbench. Also, this stuff will instantly "fog over" a metal kitchen sink *even* as water is rushing over it. So don't use your mother's new metal deep-sink to clean. Porcelain or plastic sinks is the way to go.
Periodically lift the board up out of the acid bath. You will start to see the bare fiberglass start to appear directly around the sharpie ink. This is good! Keep swishing the board around in there, and in a little while it will be finished. As soon as it is, immediately take it out and wash it with water. Your connections are there now, ready to be soldered to! Here is what your board should look like after etching.
Don't let anyone tell you (cough...cough...radio shack) that you can't re-use the etchant. Use a funnel, and pour the etchant you just used back into it's main container. Don't throw it away! After some number of boards, the etchant will quit working. From experience, I will say that a gallon of etchant will last you hundreds of small (2x3) boards. I imagine you could get 20 boards done with Radio $hack's little bottle of etchant.
Here is a setup of mine. The (highly used) gallon of etchant on the right, container on left, and circuit board with magnet wire "basket".
Cleaning: Now that all the copper connections are there for you, all you have to do is get the parts on there and test! First, use a piece of Scotch-Brite and some alcohol to remove the Sharpie ink. DO NOT use a brillow pad or a cotton rag here, this stuff catches the traces and will rip them from the board. You will notice that the longer you wait to clean after etching, the harder it is to get the stuff off. After you have bright-pink circuit traces showing, you can now tin them.
Tinning: First apply a thin paste of flux on the surface of the board. Very, very thin. Now put the (powerful) iron tip on the board and run it across each trace, applying solder. You only want a THIN layer of solder! It's easy to apply too much - but "the bigger the glob, the better the job" is only ugly here. Low power irons will have trouble here. After the board has been tinned, it will last for years on the shelf. Without the tin plating, the copper will quickly oxidize (tarnish) and be useless for soldering. Over time, the edges will actually start to disappear.
Stuffing: Provided that you WANT to solder your parts on now, you can go ahead and do so. Prepare the parts by cutting the leads off at the shortest height that will still allow you to solder reliably. After this is done, put a *small* blob of solder where each part is. Then place the part directly on this "blob", hold pressure on it, and heat it with the iron. As soon as the solder melts, the part should snap flush with the surface of the board, with a nice shiny solder joint around it. You can then line the part up the way you like it and solder the other leads/pins, then reheat the other once it is cool. 2 tips I can offer is to keep the tip of your iron clean, and don't heat the part up too much. This will take a little practice, but after a board or two you will be a pro.
So what do you think? It took me about 4 hours to make this page alone, and I wouldn't mind knowing that someone has at least read it. So email me if you don't mind!
