This Instructable will show you how to use your inkjet printer to etch your own printed circuit boards, as well as be able to display a printed component footprint on the top side of the board giving you a professional looking design.
- For this instructable you will be working with chemicals and power tools. Please wear appropriate protective wear. i.e. goggles, latex gloves, etc.
- The chemicals used in this instructable will stain clothes and your skin.
- DO NOT pour chemicals down your drain. Properly dispose of chemicals according to your local waste management.
- Chemicals used in this instructable will eat metal. i.e. your copper plumbing pipes, metal sink, etc.
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Step 1: Equipment and Materials
- Various sizes of drill bits
- Nail Polish Remover
- Copper Etchant - available at Radioshack.
- Positive Photo Resist Developer - available at various online stores. I purchased from Parts-Express.
- Daylight fluorescent bulb - available at any Lowe's
- (Optional) Crock pots - I picked up two small crock pots at a thrift store for $2.00
- Clear sheet of Acrylic around 8x10 in size
- Start/Stop Timer (picked on up at the 99 cent store)
- Plastic containers. Large enough to hold the size of your circuit board. I found some plastic paint trays at Lowe's for $1.00 each
- Presensitized PCB board - I purchased from Parts-Express (they have various sizes, and even double sided versions)
- 3M transparency film for Ink Jet Printers (this is a key component, the surface is textured, otherwise your ink would run off the sheet)
- Grafix Rub-onz sheets - I purchased from Hobby Lobby
Step 2: Designing Your PCB Files
For my project, I used Eagle Cad for my schematic and PCB design. Eagle Cad has a freeware version for hobby users that has board size limitations. I never making anything over 4" x 3" inches so it fit my needs. There is other PCB design software that you can download by searching Google.
Once your design is finished you need to print it out to size. Since this is the bottom side of the PCB, make sure you do a mirror print.
If you are using Eagle Cad, I have attached a zip file containing the CAM print job that will print your files out for you. It will make two .PS files one for the solder side, one for the component side and will also make your solder side mirrored. Once you have those files, you double click on them and it will make two PDF files that can be printed.
TIP for APPLY TEXT and Graphics
If you want to include any text on the copper side or a silhouette of an image the best way I have found is to open the .PS file in a graphics program like Adobe Photoshop. Keep the resolution of 300 dpi. You can then added textual or graphic elements to the design and they will come out crisp. You won't need to reverse the text either since the copper traces, etc. are already mirrored.
Step 3: Prepare Your PCB Transparency for the Solder Side
In Photoshop, I opened up the solder side .PS file and the copied my single circuit design to a new 300 dpi 4" x 6" file. I then laid out a grid, and just copied and pasted the design over and over to fill in the grid. This gave me a nice even layout to print.
- If you don't have Photoshop. GIMP is a nice open source alternative!
- In order to make sure I tape down the design the correct way, I always add a label to the top in normal view to the mirrored image. This way I know that the mirrored side is facing upwards. I usually just title what the circuit is.
Step 4: Prepare Your Component Footprints
With this step you are going to use the Grafix Rub-onz sheets. This time, I opened the component .PS file in Photoshop but created a 8.5" x 11" image at 300 dpi. I then created another grid and pasted the component footprint layout onto the sheet over and over again. The extra space down the side I placed some small copies of my blog logo.
When you print, make sure you mirror this image as well. The reason this image gets mirrored is because you will turn the sheet over, and then rub the bottom side to transfer the image to the top side of your PCB.
Follow the manufacturers directions that come with the Grafix Rub-onz sheets.
Step 5: Exposing Your PCB to Light
The presensitized PCB boards have photo-resist coated on them. The way the process works is everything that you have as black on your design will remain as copper. The areas that are clear, will be removed by the developer and be left with bare board.
The boards come in a foil wrapping, with a peel of white protective cover over the photo side. It's not necessary but I usually dim the lights a little bit just to be on the safe side while I am lining up my design onto the board.
Once you are satisfied with how the design is laid out on the PCB board, you can then turn on the natural daylight lamp. I have found that 14 minutes seems to be perfect timing for exposure with the lamp being 5 1/2 " away. If your lamp is closer or further away you will have to experiment with timing. The manufacturer recommends 10 minutes.
Step 6: Developing Your PCB
To develop the board: place 1 part developer to 10 parts warm water in a plastic container. Gently rock the container back and forth. Everything that was exposed to light will now wash away leaving you with a copper board and your design on it. Rinse in cold water to stop the developing process.
- Use hot tap water, just hot enough that you can touch it and not get burnt. About the temperature you would want to wash your hands with. If its too hot, the entire design will wash away leaving you with a blank piece of copper board. If too cold, the developing process won't work.
- Add the developer to the water before putting your design in. If you pour the developer directly on top of the board, it will immediately wash away anything it touched.
- After developing, if you find any areas where your traces show cracks or areas that seem to light, you can take a black permanent marker and touch up those areas.
Step 7: Etch Your PCB Board
Now that you have your developed PCB you are going to use the etchant solution to remove the copper. Everything that green (or black) on your design will be protected from the copper etchant. The exposed copper areas will be removed.
I used my Dremel and a router bit to cut out the 8 circuit boards off my 4"x6" panel. Next you will want to pour the copper etchant into a PLASTIC container and then gently rock it back and forth until all the exposed copper has been removed.
TIP: This is where the crock pots come in handy. If you use the etchant at room temperature it will take some time to fully remove all the copper. However, if you heat the etchant up, the process is a LOT quicker.
If you use the crock pot method, make sure you have good ventilation. This stuff smells bad heated, and don't inhale the fumes when you lift the lid of the crock pot!
Make sure you wear latex gloves and old clothes. The etchant will stain your clothes no matter how careful you think you will be.
Step 8: Applying Graphics to Your PCB
Once your PCB is completely etched wash it with a little soap and water and then drill out your holes for component placement.
Now comes the tricky part. Cut out one of the Component side graphics that you made earlier. You will place this inkside down on the top section of your PCB. (Make sure both are going the same direction, in my photo they are not. I did line them up correctly but when I took the photo I was holding the rub-onz wrong).
The Grafix Rub-onz are on a light colored material. To make things easier to line up, I used a small light board and laid the PCB down on it. Then when I had the rub-onz close to the PCB I could see through it which enabled me to line up the holes.
TIP: If you don't have a lightboard... you can take a cardboard box, cut out the bottom, place a piece of plexiglass on top, and a lamp underneath it.
Once you have the rub-on in place, take a Popsicle stick and start rubbing firmly over the back. Peel off paper and your footprint design will be transferred to your PCB.
You are now finished!
You could also use a hobby screen printing kit for this process, but that is a whole other Instructable.