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Creating Printed Circuit Boards - Easy (Part I)
Printed Circuit Boards (PCBs) are one of the most vital and ingenius components of modern electronics. Compared to the 'old days' with point to point wiring or tag strips, the PCB makes life a lot easier from both a manufacturing and servicing perspective.
The immediate downside of PCBs is the general difficulty of producing high quality results with household equipment. Fortunately with the surplus of technology present in our lives today generating high quality printed circuit boards is already within your grasp.
What you're going to need...
First up, let's see what you're going to need in order to generate beautiful PCBs;
- Laser Printer; You cannot do this without a laser printer. The whole principle of this PCB development system is based around the laser printer toner - inkjets will not work. Don't dispair, almost every retail store is selling at least one laser printer for under $100 AUD ($80USD). Almost all laser printers have resolutions at or above 600dpi. If you have multiple options at hand, select the laser with the lowest consumable costs, though if you only used your laser printer for PCB's then a single toner cartridge will last you a lifetime.
- High Resolution matt paper; High Resolution is the key word here. A word of warning here, highest price does not mean best results! The key aspect to making high quality PCBs is to ensure that the paper you use has a very fine paper grain (short fibers). The shorter the fibers the sharper the resultant transfer. Gloss papers often aren't suitable because there's typically a plastic barrier layer on the paper which makes it impossible for our process to work.
- Copper clad printed circuit board; Available at any reasonable electronics store.
- Cleaning materials for copper; Items such as 800 grit wet-dry sand paper, steel wool, Ajax, absorbent paper (toilet paper is fine ;), metholated spirits / denatured alcohol or acetone.
- Household iron; Any iron will do, so long as it's clean and goes up to 'linen' temperature.
- Tub of warm water; This is where we'll be spending a bit of time removing the paper.
The process...
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Print out your PCB circuit onto the high quality paper, reversing/mirroring it as required for your project. You may find that it's useful to cut your paper up into smaller sheets (A5 size etc) assuming your printer can handle such sheet sizes.
Check the print out to make sure there's no misprints. Often it's useful to make multiple copies of the same print on the sheet and select the best quality version (sometimes there are defects in the printer transfer).
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Make sure that the PCB you're transferring the circuit to is very clean. This simply cannot be stressed enough. The cleaner the PCB the better the toner will transfer and grip to it resulting in a better final PCB. For cleaning, try to use cleaning agents first before resorting to having to use sand paper. Items like acetone, metholated spirits or even Ajax powder/water should be used first, if you can't get a nice copper polish, then consider using fine (800 grit) sand paper, steel wool (I personally use fine sand paper, metholated spirits and then wash it all off and dry with a paper towel). It should be pointed out that the reason why sandpaper isn't really the best choice is because the fine grooves it leaves in the PCB can make soldering potentially more difficult.
When the board is clean do not touch the surface that you will be applying the circuit to. If you touch the surface the moisture/oils from your fingers will prevent the toner from bonding properly and most likely result in a poor etch result.
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Set the iron to 'Linen' or as high as the iron will go. We need a fairly hot iron because we're going to be forcing the toner to remelt and subsequently bond to the copper blank PCB.
If you can, preheat the PCB, using a heatgun can achieve this quite well. A preheated PCB contributes to a better transfer at times (for small circuits/boards there often isn't a noticable difference).
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Turn the paper with the PCB pattern over and lay it face down onto the blank PCB.
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The critical part...
Apply the hot iron down onto the paper and PCB, pressing them both flat and putting them under pressure. Do not move the iron around. Leave the iron to rest on the paper for about 10 seconds. Reduce the pressure a little bit and slide the iron left/right, up/down a few times. Do not swivel/twist the iron on the paper, this will result in the paper most likely shifting and ruining your work. If the paper does shift then all you can do is scrub the board back, print a new copy and start again.
DO NOT LIFT THE PAPER
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When you remove the iron from the board, you should see your circuit outline very slightly like a bumpmap. The board is now ready to go into the bath...
DO NOT LIFT THE PAPER
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Place the board into warm water (it's not critical but it does speed up the process). Leave for about 5 minutes to allow the water to soak into the paper. Some papers soak up water within seconds, others require up to 15 minutes, this is something you'll have to learn from experience based on the paper you're using.
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After a period of time, you should be able to start seeing your circuit more clearly through the paper as the paper becomes translucent. At this point, start rubbing your finger on the surface of the paper in a circular motion, you should be able to feel the paper breaking away under your thumb.
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Don't try to remove too much of the paper at once, just work your way through the layers gently, soon enough you'll get through to the 'final layer' of the paper and the copper along with the circuit will be quite apparent.
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Continue rubbing and dunking the board. Slowly all the paper will start coming off and at this point you should be able to see how well the toner has transferred (if you get any toner flaking off at this point then either your board wasn't clean enough or there wasn't enough toner on the original print (try turning off all toner-saving options).
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Finally you'll get to the point where there's no obvious paper left on the board, just the toner. At this point you need to be in a well lit room and look out for a thin layer of paper resting between the PCB tracks. Often this last thin layer can take a while to come off. Work at it with your thumb or a soft bristled tooth-brush until it appears to be all cleared.
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Set the board aside to dry. As the board dries off any spurilous paper left on the board not covered with toner will show itself as it turns white. If there is paper left, place the board back into the water and try to remove it again. Repeat this process until the board is clear. If you do not do this the thin paper film will prevent a proper etching process and result in potential bridges.
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Congratulations, you're done. The PCB is now ready to be etched how ever you prefer. You can store your boards for as long as you like without having to worry about the toner degrading. This is very useful if you want to wait to do everything as a single large etch batch.
In our next tutorial we'll talk about etching with Ammonium Persulphate.
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Additional suggestions
- Use a fine emry/polishing paste for cleaning the boards. I found that "Gumption" paste sold here in Australia dramatically improved the quality of my results. Others suggest using Ajax. I prefer these methods over the sandpaper / acetone options.
- Instead of using a full sheet of quality paper, just mask-tape the size required to a support sheet (ie, plain cheap paper). You only need to use tape on the leading-edge of the quality paper. (Contributed via IRC/chat)
- If your printer supports envelope feed, cut your paper into A5 or A6 sizes rather than wasting a full A4 / Letter sheet
- Add caustic soda to the soaking water mix to make the paper break down faster. DANGER - be very careful with Caustic soda.
- (preferred) Instead of soaking the paper, place a 6~10mm thick sponge that is quite damp over the paper and place the iron down on it, repeat this until the paper goes translucent. If your toner has bonded correctly to the copper you should be able to just peel off the bulk of the paper and then wash/rub off the remaining.
Table of printers
| Printer | Resolution | Toner | Result | Comments |
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| HP2200D | 1200x1200dpi | Refurbished unit ($68 from eBay australia) | Good to excellent | This is the printed used for these tutorials. The printer is over 5 years old and on its 4th replacement toner, no problems so far |
Table of papers
| Paper name | Brand | Paper ID/Code/Model | Cost | Results | Comments |
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| Cheap glossy magazine paper | Various | Various | $2.95 for a whole magazine | Excellent reproduction down to 10/10, possibly 5/5 | Sometimes, a really cheap solution actually works - and that is the case with magazine pages. You may have to try a few different magazines until you find a good balance between water-absorption vs pitch quality but it's well worth experimenting. Best of all, at $2.95 or so for cheap magazines it's going to save you a lot of money |
| Premium Matt photo paper, 143gsm | Celcast (by Avery) | IJ97 | $15 for 25 A4 sheets | Good | Easy to print to, though it's hard to tell which side is which depending on ambient light. Absorbs water slowly, taking about 5~10 minutes in warm water and requires a small amount of force to rub off the first layers. However it releases the toner very well without noticable chipping of the tracks. |
Table of known working combinations
| Printer | Toner | Paper |
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| HP2200D | Refurbished | Celcast Premium matt photo paper (IJ97) |
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