A printed circuit board (pcb) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. pcb's can be single sided (one copper layer), double sided (two copper layers) or multi-layer. Conductor on different layers are connected with plated-through holes called vias. Advanced PCB's may contain components - capacitors, resistors or active devices - embedded in the substrate.
This page describes a new way to make Printed circuit boards (PCBs) with a laser printer, water release paper and a hot laminating machine. I have read a lot of information regarding the use of this type of paper and have devised a method that will allow you to make perfect PCBs each and every time. I have even made PCBs that use Surface Mount Devices (SMDs) with high success. Practice, practice practice,... that's pretty much what it takes. Hopefully these notes will speed up your success rate.
Parts & Tools List
Copper-clad circuit board material
PCB drawing software (for developing the PCB traces/patterns for your circuit)
Laser printer with a resolution of 600 dpi or better ( or a quality laser photo-copier).
Water release paper (key component!)
Green TRF Foil (toner resist enhancer)
Hot laminating machine.
Etching Liquid (Ferric Chloride or Ammonium Persulfate)
Fine steel wool or non-steel scrubby.
Acetone (to remove foil and toner resist from board)
(Optional: Aquarium heater to heat etchant, PCB holder, other tools, etc...)
Printing, Fusing and Etching Instructions
DRAW THE PCB DIAGRAM/PATTERN USING PCB DRAWING SOFTWARE
My preferred software is Sprit-Layout from ABACOM in Germany or PCBExpress. Many other great PCB software products exist so check around, even download their Demos to try them out before purchasing. Purchase one you are comfortable with and one that has the features you need.
PREPARE THE BARE COPPER CLAD BOARD
Clean the copper with ordinary soap and water and lightly scrub. Use warm water and preferably a non-steel scrubbing pad. The cleaner the copper, the better the PCB resist (toner) will adhere. Don't skip his step by all means. Also, I would not use sand paper as this can leave grooves that the etchant can work under.
Dry the cleaned board using a lint free rag (be sure to leave no residue or lint, not even a finger print)
You can also clean the board with solvents such as Acetone or Alcohol but be sure it is wiped clean.
USING A LASER PRINTER, PRINT THE PCB PATTERN ONTO THE WATER RELEASE PAPER
YOU MUST USE A TONER-BASED PRINTER OR COPIER. INK DOES NOT WORK !!!! (as most inks are soluble in etching solution)
Water-Release paper is available from PULSAR as TTS paper (toner transfer System) or from DigiKey. Other PCB "release paper" exists but this by far is the best I have used.
Handling precautions:
Print only on the treated side of the paper (shiny side).
Set the printer to its highest printing density setting (usually found in printer settings/properties)
Set printer to highest possible resolution (600dpi or greater)
Handle water release paper by its edges (no oily finger prints)
Store paper is area where humidity is controlled (store out of sunlight, in sealable bag)
FUSE THE PCB IMAGE ONTO THE COPPER BOARD
The toner image on the paper will now be "stuck" onto the PCB board. With the application of heat for a period of time, along with slight and even pressure, the toner will melt enough in order to stick (or "Fuse") to the copper board. This toner will then become the etching resist, not allowing the copper beneath it to be etched.
Place the paper on the bare PCB board, with the printed toner side touching the cleaned copper board (again, be sure board is very clean, with no finger prints what so ever).
Using a laminator machine, pass them between the rollers of the hot laminator (you can place the board and water-release paper between two pieces of paper, such to act as a "carrier"). Allow the board to thoroughly cool, while avoiding touching of the paper that is now stuck to the board.
Carefully dip the board and paper in warm water and wait until the paper automatically and completely releases (around 1-2 minutes). Gently wash the board off of any residual release glue (running water). (Note: DO NOT pull off the paper what so ever... it will eventually fall off itself)
Pass the PCB in the laminating machine again, this time using Green TRF Film on top of the toner/resist. This will seal the toner surface with green foil resist, filling in any small imperfections. This will also make the PCB circuit traces more impervious to the etchant. (Note: This step can be omitted, still with decent etching results... I prefer the foil though).
Examine the traces and using a magnifying glass and touch up any resist/trace imperfections with a fine tipped permanent magic marker
Note: You could always use an ordinary clothes iron too. Be sure to completely shut off all steaming functions on the iron before using. The last thing you need is for any water/steam to exit the iron as you are using it for this application. Set iron on the "cotton" setting and allow to fully heat up. Once heated, apply constant and even pressure onto the paper which is placed on to the board. DO NOT slide the iron over the board as this might help smear the toner image, making traces smudge into each other (short circuits). With an ordinary clothes iron, you might have to repeatedly test until you determine the correct pressure and heat setting. I highly recommend a hot laminator though.... I have yet to have one board come out wrong!
ETCH THE PCB
(Note: Wear old clothes and rubber gloves. One drop of etchant will ruin your clothes, etc...). Also, be sure to perform this etching process in a well ventilated area as fumes can be caustic and unhealthy.)
Etch the board using either Ammonium Persulfate or Ferric Chloride (I use the latter).
Warming the solution helps speed the etching process, as does agitation of the PCB board in the etchant.
Occasionally observe the etching process by pulling the board out of the etchant. When all unneeded, exposed copper has been etched, rinse off the board with plenty of water to stop the etching process (I often scrub the board too to ensure the etching process has ceased).
Dry the board and then remove the toner and foil with acetone and/or very fine (#320+) sanding paper.
I also often "tin" my boards using a dipping tinning solution (see result in picture below).
Try to avoid touching the PCB traces with your fingers as this oils/dirt will make it difficult when soldering.
Note: As shown above, I built a couple of an etching tank using a plastic container (originally for storing cereal), an aquarium heater and an aquarium air pump. The air pump is connected to an aquarium aerator (air hose connected to a porous stone which is placed in the bottom of the tank) which produces bubbles in the etchant. These bubbles help etch the board in no time (breaks surface tension between etchant and exposed copper clad). I simply hang the board in the tank, turn on the heater and pump and a few minutes later I have an fully etched board. Digikey also sells a nice etching tank but for what you would pay for it ($150+), you could build 5 of them yourself for the same price!.
DRILLING THE PCB
A Dremel Tool and a #68 carbide drill will drill the holes needed (I also use #60-67 for other components as needed). Hold the PCB firmly when you are drilling and be sure to use a fairly accurate drill press (as carbide drill bits break very easily). DigiKey also sells carbide bits, but search around on Ebay as I have seen many people selling re-pointed PCB bits for well under $1 each.
Testing & Operating Instructions
I always use an ohmmeter to check all traces, particularly traces that have the potential of being shorted (not etched enough) or being open circuit (over etched).
I also often smear on a very thin layer of soldering flux onto the traces prior to soldering. This helps the flow of solder, eliminating the possibility of over-heating components when soldering.
SOLDER YOUR COMPONENTS AND TEST YOUR CIRCUIT !! YOU ARE DONE !
Additional Notes
Summary of precautions:
Clean bare PCB thoroughly (if you want, wash/scrub it twice even !... I do!)
Buy the correct water-release paper and keep it dry and clean during storage
Be sure to use a toner-based printer. Ink-jet printers do not work!
When etching, use extreme caution (gloves/ventilation) and properly store/dispose solution
*Funny (but serious) story... my girlfriend was cleaning up the kitchen one day and she threw away a pint bowl of Ferric Chloride I had used the night before to etch a few boards. She actually thought it was chicken marinate, seeing I had grilled the night before. YIKES! Lucky for me, she poured it down the drain with plenty of water.... so she said! Lucky she didn't get any on her. We'll soon see if my plumbing pipes start corroding!
Below are a few examples of circuit boards have made in the past using this exact process:
PCBWay, PCB prototype and Fabrication the Easy Way!
