New! Pictures of my business trip to China (6/2006)
http://myweb.cableone.net/wheedal/album/

I've experimented with many home fabricated PCB methods. Some were successful, others not quite so much. You can spend as much as you want tooling/buying consumables to produce good PCB's by yourself. I tend to be a bit mean when it comes to my hobbies; at least I try to be initially (almost never ends up that way.. :') ). What follows are a few comments describing my current favorite PCB fabrication method; at least until someone comes up with something that works better for me; direct inkjet etch resist printing anyone?

Toner transfer has been around for a while. There are several products/specialty papers to help to move the toner image from a paper backing to copper clad. I've had some success with the press N peel product, but the paper was expensive and not locally available. Someone somewhere suggested that glossy inkjet photopaper works well. I was able to get the image transfered OK, but I never was able to deal with the gelatin always seemed to come with it. After a bit of trial and error with the other stuff, I heard of someone using paper cut out of magazines as a transfer medium. It was cheap and I could keep trying until I got the results I wanted. It turns out to work really well.

1. Layout of the circuit board.

Basically use anything that you are comfortable with. Many hobbiests use Cadsofts' Eagle layout tool. I use the old Microsim PCboards/Specctra package --but that's no longer available. Anyway, the important thing is that it exports gerber files after you are done (some freeware packages don't do this). Lay out your board and export your component and solder layers to gerber files. Make sure the board boundary is also attached to the layers; it helps to keep the paper in place while the board is going through the laminator and also provides a line to cut down the board later.

2. Mirror the top layer. Print.

Use a gerber file viewer utility to load your newly created images. Pentalogix offers a free version of Viewmate that works really well for this. I open the top layer gerber file, select all and click the mirror button on the right side of the screen. If doing a two layer board put on a few cross hairs to the side of the layout to help align the two sides (same place on both layers).

Printing from within this program as opposed to the layout software also has the nice side-effect of not having the holes included on the copper pads, giving you a little more copper / fudge room when you drill out the board later. Print on a good 600dpi laser printer at 1:1 scale. I use an old HP Laserjet 5L.

On double-sided boards, print the bottom layer, cut out the image leaving 1-2" on one side to allow you to bind the top and bottom together. With a bright lightsource, align the two sides (toner side in o'course) using the crosshairs you drew off the side of the circuit board earlier. Check the vias and make sure the alignment seems to be OK for the whole board. I use a gluestick to bind the two sides together on the one side. This will create an envelope that you will sandwich the copper clad in when puting in the laminator later. (Now is a good time to start the laminator warming up.)

* Some have written me asking about the magazine stock that I have been using. No there isn't anything special about it. I generally look for magazine pages that have a little color background on them and a semi-gloss finish. I avoid using paper with a lot of recycled content. You can generally tell the difference by rubbing your thumb against the paper under water. If a lot of paper pulp comes off it quickly it probably has too much recycled material. Another thing I've noticed is that the higher quality pages tend to have a smoother finish and don't embed as much toner in the paper; these release easier later and more toner adhears to the copper clad.

3. Clean the copper clad.

Clean off the oxide layer with a green kitchen scrubby. These don't have the metal shavings that steel wool or similar products have and could save trouble later (board wont have tiny rust marks on it). I usually finish by scrubbing the final pass in a uniform direction, usually on the diagonal of the board. Don't worry about the fine scratches that the scrubbing action produces on the copper, it provides a surface to help the toner adhear better. Handle the board on the edges and use cleaning alchohol to finish. Dry with a shop towel. Make sure there are no fingerprints or other oil surfaces on the copper; toner will NOT stick to those areas otherwise.

4. Use a laminator to transfer the toner to the copper clad.

Temporarily hold the cutout of the circuit pattern to the copper clad while feeding the corner of the board into the laminator rollers. If you are doing a double-sided board, start with the bound corner into the rollers first. Make a couple of passes along the same direction through the laminator. This will begin to tack the paper/toner to the copper. You could us a little tape to hold the pattern to the board to help with the first passes, but that leaves a glue residue that you have to clean later, so I don't do that. The number of passes depends on the laminator heat, feed speed, and size and copper thickness of the clad you are using. Be sure to rotate the board. Experimentation is the only way to get this right. Most of the boards I've done make 6 - 12 passes through the laminator. The board in the photos did 10.

* Note that the laminator pictured is NOT modified, other than the removal of the plastic housing. The slit on the exit was at a slight angle so the thicker copper clad would occasionally jam up. I didn't have to modify the rollers to accept the 1/16" thick stock. This particular laminator has a spring loaded roller transport that allows the copper to move fairly well through the mechanism. The brand and type of laminator I use is provided in the links section below. I purchased it for $90 at a local shoppers club a couple of years ago; they are available for slightly less now.

5. Soak off the paper backing.

Fill a small bowl with luke warm water and a little dish soap. The soap helps the water penetrate the paper layer quickly. Magazine stock usually comes off within 2 minutes or less. The thin paper backing and the high clay content of magazine paper stock makes it ideal for this kind of usage. After you are certain the paper is completely soaked, start with a corner and gently ease off the paper backing. Dense toner areas will hold a bit of paper, while clearer areas of the boards release easily.

6. Clean off the board.

Under cold running water rub the paper pulp off of the toner traces. Pay particular attention to the tight spaces between traces and smt pads. Any paper residue in an unintentional area will act as an etch resist.

Check for any drop out. If there is just a tiny amount you can do spot repairs with a perminant marker. I use a Staedtler red marker; the ink will act as a resist as well.

If there is too much dropout, just clean off the toner with a green scrubby and try again. (Goto step 2)

7. Etch the board.

The secret to a good etch is warm solution and some agitation. Some people use an aquarium heater, airpump and a bubbling stone to provide heat and agitation. I'm cheap so all I do is fill a sink or a large plastic tub with hot water (2-3 inches depth) use a pyrex or similar glass bowl filled with etchant. Let it set for a few minutes to heat the etchant. I attach a coated wire or a zip tie to the board and manually "swish" it around in the etchant. Unpowdered latex gloves are a must here. Be careful with FeCl (my etchant of choice), it stains anything porous. Ventalation should be provided. Check periodically. When it looks like everything is etched properly, etch 30 seconds or so more to be sure. Rinse the board in clean, cold water and inspect. Etch longer if necessary. Clean up the etchant / supplies.

8. Clean off toner.

Some suggest acetone or other chemicals to remove the toner; citing that physical scrubbing could damage fine traces. I just use a green scrubby and scrub in very small areas at a time and very carefully. I haven't damaged anything yet doing it this way .

9. Cut to size.

Trim excess material from your PCB with a lanolium knife and a straight edge. Score lines in the material until it is a sufficient depth to snap a clean break on the board. (Do this on both sides). Snap the board --using a vice will hold the board firmly while you make the break. Sand the edges with fine grit sandpaper.

10. Drill holes.

I use a drill press, crossvice and solid carbide small drillbits. I got everything from Harbor Freight. I mounted the crossvice to the drill press and a bit of clear pine in the vice. Screw the pcb to the pine in the vice with a couple of screws on the edge. Align the board by checking if you can move one vector along an IDC connector or a large dip on the board without correction from the perpendicular axis, tap with the end screwdriver to correct and reverify. The drill I have is not a sensitive type so it is really easy to break bits if you get into a hurry. I usually make 3 passes into each drill hole, blow off the tip each time and drill a little deeper. Having the wood underneath helps to keep the tear-away to a minimum when you penetrate the bottom side. Check that your pads/vias are truely aligned.

11. Populate board.

*Optional -- Apply tinit to board to help with solderablilty, copper oxidation. --Not necessary but it looks nice.

Attach components as normal. Well, not quite normal, remember there is no solder mask so be a little more aware than you would be stocking a professionally produced board. Also, doing one offs/ prototypes I tend to avoid drilling holes when I don't need to so I sometimes surface mount dips and IDC connectors. After a few builds with this method you can pick up tricks when laying out board to help you later when stocking parts on your board. A few things I do are to use a little larger than normal pads when I plan to surface mount dips and IDC connectors; always come out with straight traces for a few mills when using smt components to extend the pad a bit to give you more room with the soldering iron, and keep in mind component heights and soldering iron clearance when organizing where your components lay. I tend to try to keep everything 12mil where I can. You can lower the DRC rules to 6 mil clearance to help you do that. It is possible to go smaller, but 12-6 is comfortable, less than that you have to be more careful. The board shown has a 3.9 mil clearances on the smt pads and a few 10 mil traces.

You can apply a small bit of solder on circuit traces to make it look like you used a tinning solution ealier. Solder braid helps to flatten the solder. Remember Flux is your friend. I use water soluble to make cleanup easy.

Wash under a hot tap and use an old toothbrush to remove flux. Dry. Check connections and solder joints, verify IC's don't have solder bridges (especially fine pitch smts shown in the picture above.) Try your new board!

Conclusion:

Some have said that using toner tranfer and magazine stock is only suitable for bulky electronics with large clearances and 15 mil or greater traces. With a bit of practice you can do much better than that. It's my current favorite because 1. It is very cheap (once you have some equipment) 2. It's very fast. If you know what you are doing you can get a board printed and etched in less than an hour. I still send more complex boards out to be done, but if you want to try something out like a circuit fragment or something relatively simple (only a little drilling) and are in a hurry, this is a good way to go.

An example of a fairly complicated board using this method:
CPU_BOARD

Here are some handy links:

Eagle PCB Layout tool --Cadsoft --Freeware for limited model, $ up from there
http:/www.cadsoft.de

Gerber Viewer "Viewmate" -free download
http://www.pentalogix.com

3M Green "Scrubby" --Scotch-Brite Scouring pad --grocerystore (anywhere) $.79
http://www.cleansweepsupply.com

Magazine --Any good trade rag, catalog --$0.00
http://www.sharperimage.com

CopperClad -- 4.5"x6"--$4
http://www.radioshack.com --catalog #276-1499
(very thin clad -- cuts with sissors) --(pcb)N4105 -- 12"x24" - $7
http://www.surplussales.com

Royal Sovereign NR-900 Laminator --Sams Club --$90
http://www.royalsovereign.com

Red Marker --Staedtler lumocolor red 313 --craft/drafting store --$1.39
http://www.staedtler.com

Small Drill Press --Sale $39
http://www.harborfreight.com

Cross Slide Vice --$39
http://www.harborfreight.com

Solid Carbide *tiny* drill bits --$13 for 50
http://www.harborfreight.com

FeCl Etchant --$4
http://www.radioshack.com--catalog #276-01535