I no longer recommend that people make their own printed circuite boards. The cost of sending your printed circuit boards out to be manufactured is quite cost competitive with manufacturing own. Here's a couple of links to a pair of outfits in North America that specialize in prototype manufacturing:
Fabricating a printed circuit board consists of the following basic steps:
Laying out the printed cirucuit board is covered in the section on hobicad. There are a few hints that should be observed:
It is worthwhile to do a commerical plug here for DyanArt Designs here. DynaArt Designs markets all of the material needed to perform printed circuit design using laser printer toner. They can be reached at 805-943-4746 from 9:00 to 6:00 Pacific Time, Monday through Friday. While it is fairly easy to fabricate printed circuit boards without using any of the DynaArts Designs products, many people will find the DynaArt products to be quite convenient.
The only real trick for printing resist patterns onto paper is that you need to find the right kind of paper. What you are looking for is a paper stock that a laser printer can print on, but when heat is applied, the toner will choose to stick to the copper rather than the paper.
DynaArt Designs sells toner transfer paper the has this characteristic. The paper stock is sort of expensive, but you will not be using it very fast. An alternative that has been written up in {reference to Laser printer book by Black Lightning goes here} is to purchase some laser printer label stock (e.g. Avery), peel off and dispose of the labels, and print directly onto the waxy label surface. The choice is yours.
Use the following steps to transfer the resist pattern from the paper stock to the copper board.
Etchant is just a polite word for a very strong acid that can desolve copper metal. Etchants are quite safe to use, provided appropriate care and handling is observed. So please, read this section carefully.
First, the legal libability and disclaimer stuff. I find etching printed circuit boards to be quite easy. You might not have such an easy time of it. If you have problems, they are your problems, not mine. Do not sic any lawyers on me, because any experimentation you do with etching printed circuit boards is being done at your own risk and with NO LIABILITY TO ME!
The two most commonly used etchants are ferric chloride and ammonium persulfate. Both are desolved in water and the board is dipped into it. Ferric chloride is a sickly blackish brown color when desolved in water. Ammonium persulfate is clear when desolved in water.
Etchant is poisonous (as are many household chemicals, such as ammonia cleaner, lye, detergent, etc.) This means that etchant must always be kept in labeled container that names the chemical and with the skull and cross bones symbol that is the universally accepted symbol for poison. Any labeling must be done using an indelible marker. If you do not have an indelible marker, stop right now and buy one! Do not skimp on the indelible marker, most markers are water soluble. Since the etchant is desolved in water, the slightest spillage is quite likely to erase a water soluable marker.
As with all posionous chemicals, etchant must be kept away from small children. If small children are around, I recommend that you use ferric chloride as your etchant, it does not look at all appealing to consume. The ammonium persulfate has the characteristic that as it gets used, it turns a pretty clear bluish color that looks quite attractive and yummy to a small child that does not know any better. You will hate yourself forever, if you screw up and do not take adequate precautions to prevent a child from consuming etchant. (Remember, this is no different from any other household poisonous chemical.)
Most people's image of acid is that if the slightest speck of it gets on you, it will eat a hole straight through you and you will die a horrible hissing death just like the the wicked witch in the Wizard of Oz. The reality is that etchant is very good at disolving some metals, such as copper, but really does not do much to organic compounds such as skin. Indeed, if etchant could eat through organic materials, the toner that we use for resists would not be useful for controling the etching process. If any gets on your skin, it is prudent to wipe it off quickly; however, it is completely unnecessary to call a doctor. I use thick rubber dish washing gloves whenever I handle the etchant, since no matter how careful I am, some spashing always seems to occur. Also, I tend to use old shirts that I don't particularly care about. If you can find a rubber apron, it would not hurt to wear it.
One place where you want to be quite careful not to splash any of the echant (acid) is in your eyes. If you do not wear glasses, be sure to be wearing some sort of protective goggles. If somehow, despite all of your precautions, some echant gets splashed into your eyes, be sure to flush it out with plenty of water, then check yourself into your local emergency room and have an eye specialist make sure that things are OK.
Echant works faster at higher temperatures. There are several ways that it can be warmed up. While both a stove and a microwave will do a perfectly adequate job of warming the etchant up, I have always been a bit concerned that the vapors that come off might contain just enough of the echant to evenutally get mixed into your food. So, instead, I recommend using a heater that is away from food preparation. A hot-plate is one possibility. Another very effective heater is an aquarium heater; for aquarium heaters, the heating element is protected by glass.
If you have a single layer printed circuit board, it can easily be etched in a flat tray of warmed etchant. Double-sided printed circuit boards etch more evenly if the etched vertically in a tank. In order to etch the board vertically, I drill a couple of small hole on either side of the board, thread some nylon thread through the hole and hang the loops on some pencils laying across the top of the etchant tank.
Once you have heated up the etchant, just dip the board in and slowly agitate the echant. Every few minutes to pull the board out to see who far you have gotten. When all of the excess coper has been removed, pull the board out and rinse off the board with a little water. Adding a few drops of water to the etchant will not dillute is significantly.
Ectchant can be resued until it is totally depleted. For ferric chloride, there is now easy way to figure out when it is depleted. Some sediment (copper ferride?) forms at the bottom on the container, but it hard to judge the amount of depletion from the amount of sediment at the bottom of the container. Similarly, for ammonium persulfate, the etchant turns a bluish color when it is nearing depletion, but it is hard to judge depletion from the color blue. About the only way I've found to discover whether echant is depleted is to stick a board in and if it stops being etched, the echant is depleted and it is time to be renewed. I suspect that just about any chemist could come up with a better way of figuring out the amount echant depletion, but I am not a chemist and I do not know a better way than just trying it out and seeing.
The next obvious issue is the proper disposal of depleted echant. Please to not attempt to etch your own printed circuit boards without planning on properly displosing of the depleted etchant. Some communitities have figured out that it is better and cheaper to collect hazardous wastes from households than it is to let them get disposed of in an improper fashion. If you are not a member of such a forward looking community, you can try to get the outfit who sold you the echant to tell you of a safe way to dispose of the echant. If all else fails, it possible to store the echant for a long time and hope that your community eventually adopts a more sensible attitude towards hazardous waste.
I store my etchant in couple of properly marked 1 gallon plastic water bottles. My echant tank consists of a plastic water filter tank for an aquarium; it seems to be just the right size for the boards that I etch. I insert an aquarium heater in the tank and crank it up all the way to heat the etchant as much as possible. I spread newspapers out under the etchant tank to catch any unintentional splashing. I have used both ammonium persulfate and ferric chloride. When I was single, I prefered ammonium persulfate, but now that I have a small child in the family, I prefer ferric chloride. For some reason, it seems to be easier to purchase ferric chloride through mail order than ammonium persulfate. When I am all done etching, I pour the etchant back into the plastic water bottles using a plastic funnel.
Before drilling the holes, the resist is cleaned off the remaining copper using a kitchen cleanser. I use number ?? carbide drills to drill the holes. I purchased an inexpensive motor tool (e.g. Dremel) and a small drill press to mount it into. Drilling holes in fiberglass printed circuit board works best if the drill bit is spinning as fast as possible. No matter how careful I am, I eventually break one of my carbide bits. Thus, it is useful to several bits available to deal with the inevitable bit breakage. When you are drilling the holes, be sure to wear eye protection, to protect against flying broken drill bits. Your bit is getting dull when it tends to lift each copper pad off of the board rather than drill through the board; when this starts to happen, either sharpen the bit with a grinding wheel or replace the bit with a new one.