Step 3: The PCB
I made the circuit board using the toner-transfer method. It's my new favourite method of making boards! It's faster than the photo-resist method, and it's easier to produce good results. Oh, it's also cheaper and doesn't produce as many waste chemicals.
I won't go through the whole process here, there are plenty of guides online. But, I'll go over the basics.
Start by printing out the PCB artwork. The toner transfer method requires you to print using a laser printer on glossy photo paper - use the smoothest, shiniest stuff you can get. The bottom artwork should be printed normally, and the top artwork should be a mirror image.
Cut a piece of plain double-sided copper clad board slightly larger than the artwork, and place either the top or bottom artwork with the printed side towards the copper. Be sure the copper is clean to ensure a good transfer. You may tape the artwork to the copper clad using heat-resistant tape, to prevent it from sliding around. Now, place the board on an ironing board with the artwork on top, and lay a piece of plain paper on top. Some photo paper contains plastic that will melt onto the iron - the plain paper prevents this.
Now, with the iron on the hottest setting (and no steam!) , press down on the board for a few minutes. It's not necessary to move the iron unless the board is bigger than the iron.
After a few minutes, remove the iron and place a heavy, heat-resistant object like a cooking pot or glass baking dish on top of the board. This will keep the paper pressed against the board while the toner cools.
When the toner and board are cool, peel off the photo paper. If you're lucky and are using photo paper like I have, it will peel right off leaving the toner securely adhered to the copper. Some photo papers may require you to lightly scrub off the paper under running water.
Now, note the four mounting holes in the corners. Drill a 1/32" pilot hole in three of them. Take note of which holes these align with on the second piece of artwork, and punch a small hole in these locations on the artwork with a pin. When you line up the second piece of artwork on the copper clad board, make sure these holes line up PERFECTLY.
To prevent the toner that's already transferred from sticking to anything, lay a plain piece of paper on the ironing board, then a piece of unprinted photo paper, then the board and remaining artwork. Apply heat with the iron as before.
When both sides are transferred, inspect the board carefully for any toner that didn't transfer, and for any other damage. Repair the damage using a black fine-tip Sharpie marker.
Etch the board in either Ferric Chloride or Ammonium Persulfate according to the directions on the bottle. Inspect the board regularly to make sure that the toner and any repairs are not being etched away. When the etching is complete, thoroughly wash and dry the board with a lint-free towel. The toner and Sharpie marker are easily removed using nail polish remover and a cotton ball.
The last step is to drill the holes. I used a 1/32" bit in my drill press. This step seems to take forever, but be patient and be sure to drill in the exact centers of the holes.
I won't go through the whole process here, there are plenty of guides online. But, I'll go over the basics.
Start by printing out the PCB artwork. The toner transfer method requires you to print using a laser printer on glossy photo paper - use the smoothest, shiniest stuff you can get. The bottom artwork should be printed normally, and the top artwork should be a mirror image.
Cut a piece of plain double-sided copper clad board slightly larger than the artwork, and place either the top or bottom artwork with the printed side towards the copper. Be sure the copper is clean to ensure a good transfer. You may tape the artwork to the copper clad using heat-resistant tape, to prevent it from sliding around. Now, place the board on an ironing board with the artwork on top, and lay a piece of plain paper on top. Some photo paper contains plastic that will melt onto the iron - the plain paper prevents this.
Now, with the iron on the hottest setting (and no steam!) , press down on the board for a few minutes. It's not necessary to move the iron unless the board is bigger than the iron.
After a few minutes, remove the iron and place a heavy, heat-resistant object like a cooking pot or glass baking dish on top of the board. This will keep the paper pressed against the board while the toner cools.
When the toner and board are cool, peel off the photo paper. If you're lucky and are using photo paper like I have, it will peel right off leaving the toner securely adhered to the copper. Some photo papers may require you to lightly scrub off the paper under running water.
Now, note the four mounting holes in the corners. Drill a 1/32" pilot hole in three of them. Take note of which holes these align with on the second piece of artwork, and punch a small hole in these locations on the artwork with a pin. When you line up the second piece of artwork on the copper clad board, make sure these holes line up PERFECTLY.
To prevent the toner that's already transferred from sticking to anything, lay a plain piece of paper on the ironing board, then a piece of unprinted photo paper, then the board and remaining artwork. Apply heat with the iron as before.
When both sides are transferred, inspect the board carefully for any toner that didn't transfer, and for any other damage. Repair the damage using a black fine-tip Sharpie marker.
Etch the board in either Ferric Chloride or Ammonium Persulfate according to the directions on the bottle. Inspect the board regularly to make sure that the toner and any repairs are not being etched away. When the etching is complete, thoroughly wash and dry the board with a lint-free towel. The toner and Sharpie marker are easily removed using nail polish remover and a cotton ball.
The last step is to drill the holes. I used a 1/32" bit in my drill press. This step seems to take forever, but be patient and be sure to drill in the exact centers of the holes.
- I may order a bunch of professionally-made boards from a boardhouse, at a cost of about $12 each plus shipping. If you're interested in a group buy, let me know! *
Remove these ads by
Signing Up
Visit Our Store »
Go Pro Today »
However, the toner transfer method can be a bit finicky. There are a number of factors that can affect the transfer - the type of toner the laser printer uses, the "darkness" of the toner, the type of paper used, the cleanliness of the copper clad board, the temperature of the iron, the pressure used on the iron, the amount of time the iron was pressed on the board...
So, I assume that the toner transferred in some places, but not others? Try cleaning the board really well with fine steel wool. That helps the toner "stick" to the copper. Also try different types of paper. Some people have better luck with photo paper, others with glossy magazine paper. Or, you could try the dedicated "blue" toner transfer paper.
Another thing to watch out for is air bubbles. I think, but have not confirmed, that air pockets can form between the paper and the copper, preventing a good transfer.
Good luck!
http://www.futurlec.com/index.shtml
Thanks though. :)