Printed Wiring Boards.
Updated April 11, 2009.

Now that computers and laser printers are a common part of the household or office, it is possible to make high quality printed wiring boards with very little additional material. The only additional material that might be needed is to purchase some Staples PhotoBasic gloss ink jet paper. I buy the 100 sheet pack (Staples SKU 471865). This has a plastic coating on top of the paper.

And yes, you will be using a laser printer on ink jet paper, printing on a ink jet won't work. Laser toner is a mixture of carbon black and hot melt glue. This will transfer when heated again. Water/oil based inks will not transfer!

To make a PWB, the first step is to create or reproduce artwork in your favorite graphics program. (I use Visio for the PC or MacDraw Pro for the Macintosh). After you finish your artwork, use the "group"and "duplicate" functions of the graphics program to make several copies of the artwork on a single page. This method can be used to produce a single card to a modest production run.

VERY IMPORTANT Prior to printing, make a MIRROR IMAGE of your artwork. This can be done several ways. Many of the laser printers drivers have an option under the Properties, then the graphics tab, to make a mirror image. Failing that, use your graphics program to invert or flip your image. Now print your image.

Prepare the Copper stock.

• Cut to size, since I use 8.5 x11 inch paper I have been cutting the copper stock this size on a table saw.  I  duplicate the image in my graphics program to fill up the page.
• Clean copper with a scotchbrite or fine steel wool. Use a cross hatch pattern. The little micro scratches gives the toner somthing to grab on to when you do the trasnsfer. A fingerprint will mess up the transfer.
• Clean again with acetone until a paper towel or rag comes away clean.
• Debur the edge of the card stock with a knife.
  

• Place artwork face down (printed side) to the coper stock.(This is the reason for the mirror image.)
  
• Using a standard laundry iorn, iorn the image to the paper. Set the laundry iorn as hot as it will go and use lots of heat, lots of pressure. (Note: In the intrests of domestic harmony, find an old laundry iorn at a yard sale, don't use the household laundry iorn.) Do this on a surface that will take the heat. I use a marble slab cutting board or the glass range top in the kitchen.
  
• Iorn until the image on the back side can be seen through the paper.
• Let cool to touch, now move the card stock to the sink, plug the sink and fill with water. Let it soak about 20 minutes.
• Peel the paper off the stock, the paper will come off in layers and then you may have to use a scotch brite scrubber to get off the last layer of emuslion and plastic. The last layer is very tough.
• Dry and touch up the artwork. Use a Sanford sharpie to touchup up any breaks or holes in the artwork.
• Make sure the emulsion is removed between traces.
• Let it dry, the black lines turn an off white when dry.
  

• Prior to etching, safety precautions please, what is use is caustic and has fumes. Do this outside near a garden hose. The etchant will eat most anything metal, so dont use your inside stainless steel sink. Plastic vessals only,  dispossable plastic gloves, and eye procection. I usually use a 5 gallon bucket upside down as a work platform then a kitchen plastic wash basin on top of that.
  
• A home made etch can be made using 2 parts 3%  Hydrogen Perixoide (H2O2,  any drug store about $1.00 to $1.50 a quart) to 1 part Muratic Acid (any hardware store or pool supply about $5.00 a gallon). I usually use the whole quart (4 cups) of H2O2, and a half quart (2 cups) of Muratic Acid. Pour the H2O2 into the basin then slowly add the Muratic Acid. Buy your own measuring cups for this and do not mix with the household cooking measuring cups.
• Place card stock into etching bath. Etch turns green as the copper is disolved.
  
• Agitate solution constantly. I use rubber gloves and a plastic disposable fork to keep the etchant moving over the printed image. This etchant works very fast. Hold breath, agitate a bit then move away and breath.
  
• When etching completed, stop the etching process by washing in running water. I do the etching process outside near the garden hose for this reason.
• When the etching is finished, pour the used etch into the 5 gallon bucket, dilute the etchant some with about 3 gallons water then neutralize the etchant with a LARGE package of baking soda. Add a little at a time. Its going to foam up so be prepared to wash down the green foam with the garden hose. Add baking soda until there is limited or no reaction. When neutralized, pour out in yard somewhere or down a sewer drain. Rinse and clean your equipment with running water.
  

• Remove the black etch resist with acetone.
• Cut to final size.
• Drill card per your drill schedule.