- copper clad board
- HCl Hydrochloric acid
- H2O2 Hydrogen Peroxide
- inverted pcb layout
- glossy magazine paper
- laser printer or copier
- water boiler
- plastic containers
- plastic tweezers or pliers
- steel wool (000)
- maybe Sharpie or black marker for writing on CDs
- safety goggles
- rubber gloves
STEP 1: preparation
- Cut out the layout pcb and measure the size of copper board you will need. Cut the copperboard to size.
- Clean the copper board with the steel wool 000, don't be lazy, clean it well, it will save you time later.
- Once it's shiny and clean, remove all the dirt and scraped off residue with a cloth soaked in acetone.
Normal board to the left, the cleaned board to the right in the background.
STEP 2: ironing the layout on
- Before you start ironing, take a needle or exacto knife to punch as many holes in the tonerless areas of the transfer
- Take the iron and remove all the water it may contain.
- Put it on 'Linen' (hottest you can go) and wait until it's hot.
- Put the paper on the pcb, hold it on one side so it does not slip.
- Now apply the iron to one side of the board while keeping the paper in place. Do not move for about 15 seconds. After this time, the paper will stick to the copper due to the heat.
- Now gently go over the rest of the board and really iron it so as to remove air from underneath the paper. Then put your iron flat on the whole board and apply pressure for about 2 minutes.
- Then iron the board top to toe, left to right. Just iron the hell out of it and don't be afraid, the paper won't catch fire. Unplug the iron temporarily if it indicates it's overheating.
- When you feel your done (depends on the board size), throw the pcb with transfer still sticking to it in a bowl of lukewarm water. Too hot and your toner may come off, too cold and the board will shrink fast and thereby maybe damage toner traces.
STEP 3: removing the paper
- After the paper has soaked for some minutes, you may be able to peel it off by rubbing your thumbs over the surface of the board.
- If parts of the toner come off in this process, there is only one reason: you should have applied more heat in that area. If this is the case, clean the copperboard with steelwool and acetone and start over again.
- A good technique is to start rubbing the center of the board with your thumbs. The paper will then come off layer by layer and if you applied enough heat the chances of damage are minimal. Keep on rubbing, don't be affraid. If the board goes dry, soak again then continue rubbing.
- You know when you're done when all copper is bare. If paper is still cover the traces themselves, this does not matter. Just make sure the etchant will be able to get into contact with all the copper that should be removed.
STEP 4: Etching
BE SAFE -- please wear at least industrial rubber gloves and do this in a well ventilated area or outside. Don't bring any metal in contact with the etchant, it eats metal. Use only plastic or glass containers and tools.
For 1L of etchant you need:
- It will speed up the proces if you heat the etchant, either by using warm (not boiling!) water to dilute the chemicals, or by putting the etchant container in a second container fill with hot water.
- Stirring the etchant or the board CAREFULLY also helps. Don't breath the fumes, stand away if you're not stirring or checking how it goes. It takes some time, dependent on the size of the board. Be patient and watch.
- First thing you'll see is the discoloration in the etchant, from transparant to yellow and later green.
- For some time, it will seem like nothing's happening, but if you look carefully, you can see the copper getting darker
- The etching process reaches its final stage when you see the edges being cleared
- Copper dissapears completely from outside towards the inside of the board
- All copper is gone and only the traces are still visible. Time to take out the board using tools and to rinse it properly in cold water.
STEP 5: Finishing
- You can clean the board by using either steel wool or acetone. Both work equally fine in removing the toner.
- One last step would be drilling, but there are surely other threads about that subject.