My first etching tutorial was both my first tutorial, and also a tutorial in a subject that was fairly new to me at the time. In other words, it sucked. Big time.
This time I’m going to try to do it right, and have photos to prove it, So lets get started. Today I’m going to teach you, or make a feeble attempt at teaching, how to etch a board, from start to finish.
Bill of Materials:
- Etchant of some kind. I use ferric chloride simply because I have a bottle that I haven’t used up of it laying around, however it doesn’t always work the best and is a little messy.
- Baking soda
- nail polish remover, preferably the kind that has acetone in it, or if you have it, plain acetone is even better.
- a few Q-tips
- Cotton round. Depending on if you have etched or not before, you may or may not need these. I use the “Sponge” method of etching, which is what these are for, however if you use an etching tank or other form of etching then ignore this.
- Copper Clad, only a small amount for the board we’ll be etching today is needed and only single sided is good, but double sided works also, you’ll just have to etch off the extra.
- Drill press and either HSS or tungsten carbite drill bits.
- Some method of cutting Copper Clad.
- Water (for etching and yourself).
- Good, well ventilated work space.
- Transparency’s for laser printers or copiers, I use 3M PP2500.
- Iron, preferably one that has adjustable temperature.
- Soldering Iron and solder.
- One of these and 4 header pins and 3 0603 1k ohm resistors.
- And finally, a laser printer, computer to print from that preferably has Eagle on it. (and possibly the Sparkfun parts library)
This time we’re going to start small, and by small I mean both with parts, parts count and over all size.
First we need to look at the design, typically you would create this, but for the ease of the tutorial I have a small breakout board for the RBG surface mount LED from Sparkfun that we will etch. This board uses 4 header pins to breakout the tiny pins that the RBG LED has to breadboard friendly spacing. Along with this the board also includes 3 current limiting resistors so they are not needed out side of the breakout board.
There are pictures, however since our nice camera decided to so kindly die, they are all taken with my Palm which doesn’t have that good of a camera.
The LED we’ll be making the board for… Whatever you do, don’t sneeze, breath or cough around this guy.
And the design, with a few extra bits to test the etching with.
You can grab the Eagle files here.
First print out the board in Eagle by pressing the print button, clicking on the “Solid” “Black” and “Up side down” check boxes then print. You should print a trial on paper first to make sure all the pin layouts are going to work and what not, and if they do then you can print to your transparency, But just remember which side has the toner on it cause it can get hard to tell.
Next we want to prep the board for the toner transfer. First off, put on your gloves now if you don’t have them already. the gloves help oil from getting on the board which will effect how well the toner sticks to the copper, and later on they will help keep the toxic etchant away from your hands. I like to scrub my board down with dish soap, then sand it smooth with fine grit sand paper, and then finally wash off all the sanding dust and clean the board with alcohol and allow it to dry very well. Some people recommend placing the board in an over for a few hours to fully dry out the board, I don’t for the time being however, and this is your own choice, if you think it will help then go for it.
Pump that iron! well…maybe not pump but definitely plug it in and let it heat up. as it’s heating up take your transparency and place it on the board toner side touching the copper. if you want you can cut the transparency to size, after you have it laying down you can take some tape and tape the edges down, but try to keep the transparency as flat as possibly.
Because of the tape I like to place my board in a piece of paper folded in half to keep the tape from melting on to my iron. This next step you may have to repeat a few times to find the right temperature for your iron, however mine has a “cotton” setting that I am just above if that helps any. When you iron the board you want to place your full weight, or a fair amount of it on the iron, and also want to let the iron sit for a few minutes on top of the board to let the toner melt. After those few minutes have pasted you can start moving the iron around the board, trying to get every inch of the board an equal amount of pressure to make sure the toner melts and sticks everywhere.
If you ever need to repeat this step you can use nail polish remover, or acetone to remove the toner, then clean the board again and try the ironing, once more.
When you think you are done, which should be several minutes, often 5 to 10 minutes for me, you can turn your iron off and let the board cool down. Don’t try to put the board in cold water to cool it down, or blow on it, simply set it off to the side and let it naturally cool down, or else you run the risk of cooling the toner to fast ans having it flake of the board or not stick.
(You can skip this next part if you use a different form of etching such as an etching tank. If you want to build an etching tank, Adam Greig aka Randomskk has some good food for though in his photos and this blog post)
If all goes well, when you pull off your transparency the toner should stick to the board and look amazing. If you see any parts of the toner that didn’t work, if they are small enough you can use a sharpie to fix the mistake. If you haven’t already, you should cut your board to size to avoid having to etch away all the extra copper. This is where the baking soda, water, cotton rounds, and etchant. The baking soda and water are to help neutralize the etchant after your done, and in case there is a spill. First get your cotton round wet with etchant, then take your board and start to wipe around the board, I tend to wide in somewhat of a circular fashion and tend to focus more on the edges as they seem to etch the slowest for me.
After the etching is done you can take and drop the board into the water and baking soda mix. This will stop the etchant from eating away at more copper. Next take the board over to a sink and wash off the baking soda and water mix, and then clean the board to make sure everything is off. The cotton swabs can also be put into the water/baking soda mix, and this mix can then be set off to the side somewhere where it will not get moved, and the water allowed to dry off. The left over powder you can most likely take to a Hazmat disposal place and have it taken care of.
The Finished board, the copper that I didn’t etch away isn’t needed, and was more of a printer testing than an etch test.
Now we can cut the board all the way down if you haven’t already, and drill the holes for the four header pins out. I used my drill press (which recently got HackADay’ed) to drill first since it was easier to drill with a larger board, then I used a dremel cutting blade to cut the board down to size. As the above photo shows, ear protection, eye protection, and also not shown, lung protection is needed during this step.
Getting ready to drill…
Drilled and cut to size. Next step is soldering. Since this is not a soldering tutorial, I will leave that to you to figure out for today, However, in order to solder, you need to remove the toner. To do this you will need the nail polish remover, or acetone and will want to cover the board in it and let the board sit for several minutes. After this a Q-tip works great for rubbing the toner off.
And now the final results of the board. I am still waiting for new resistors to come in so they currently are not soldered however the RBG LED is. These photos show the over all size compared to two I2C chip breakout boards from Sparkfun, and then the testing of all three colors of the LED after being soldered.
Hope your board turns out just as well, if not better. Feel free to mess around, change a few things, or even change settings on your printer for how much black is printed. Experiment around and see what happens. Give it a few months and you’ll get the crazy, half brained idea to write a tutorial also. If you do fire me off a link and I’ll link it in this tutorial.