Introduction: Homemade Double-layer PCB With Toner Transfer Method

Home made Printed Circuit Boards (PCBs) are a great way to try out your prototypes before sending them for manufacturing. The toner transfer method is a simple way of making PCBs because all you need is a printer, an iron, some laminate and etching agent. However, if your design requires two layers, your challenge is to align them. If you fail to do so, your vias will not connect the layers properly. You might also run into a situation in which you drill through a pad on one side but end up on a net on the other.

In this instructable I will show you how to make a double-sided PCB at home without any extra equipment. It is my first instructable so feel free to let me know what can be improved. Here we go!

Step 1: Print

To begin with, you need to have your board designed. I use Eagle CAD, but it can be any other PCB design tool. Although this instructable is about two-sided PCBs, I recommend using as few vias as possible as this will limit the amount of work later on. It's recommended to include mounting holes in the corners. Even if you don't need them, they will make aligning the layers easier.

Once you're done, you can print your design on glossy paper. Remember to use maximum toner density and resolution.

For the top layer, print the design as a mirror reflection. Include nets, vias and pads. In Eagle I add the dimension layer to make cutting the board easier.

When you print the bottom part, make sure you do not select the "Mirror" checkbox. Otherwise you'll end up with a print that you'll need to transfer through paper. This may be difficult. For the bottom layer include nets, dimension and vias. It is not necessary to include pads.

Step 2: Prepare the Board

Time to get your hands dirty! We'll start by getting the laminate ready. Cut your print along the dimension layer lines with scissors and use a marker to get the dimension on the laminate. Now you'll need to cut the laminate. You can do it with a small saw or very sharp scissors. Once done, remember to clean the top layer well to remove any dust and grease. I use a kitchen sponge and extraction naphta, but any good solvent will suffice. Wear protective gloves!

Step 3: Transfer the Top Layer

The next step is to transfer the printed design onto the laminate. Start off by carefully aligning the print with the laminate you prepared. Make sure not to touch the laminate as grease from your palms may prevent the toner from transfering properly.

Set your iron to max, do not use steam. Keep pressing the iron for about 5-6 minutes. Move the iron around, especially close to the edges to ensure the toner is fully transferred. Towards the end, you should be able to see the PCB layout through the paper. This means the toner has melted and you're ready to remove the paper.

Let the PCB cool down for about a minute and place it in lukewarm water. It shouldn't be hot, but it should not be cold either. About 40-50 degrees Celsius should be just fine. Leave the board be for a while until you see the paper starts peeling off at the sides. You can now gently remove the paper from the board. If it doesn't come off easily, give it some more time.

Step 4: Align the Bottom Layer

Now that you have the top layer on the laminate, it's time to take care of the bottom layer. Start by drilling holes on your PCB. It is recommended to use mounting holes in the corners of your PCB. Even if you don't need them, it is recommended to include them just for this purpose (thanks to MikB for this tip!). If you don't have mounting holes, use vias. You don't have to drill through all of them yet and in fact it's better if you select only those that are as far apart from each other as possible (e.g. close to corners). You will use them to align your bottom layer with the top one. If you drill through vias, small pieces of toner may come off during drilling. Do not worry about this, just make corrections with a PCB marker if needed.

After the holes are drilled, clean the bottom layer to remove dust and grease. Now take the paper sheet with the bottom layer of your PCB printed on it. Punch holes through vias using pins. Then, push the pins through the holes drilled in the PCB, with the paper sheet still on them. This way you've just aligned both layers of your PCB.

You can't use your iron just yet because pinheads are in the way. I use insulation tape (more temperature resistant than regular tape) to stick the paper to the board. Avoid putting tape over the nets of the top layer. As pointed out by rocketman221, Kapton tape works really well for holding the paper on the board. It doesn't melt and leave sticky residue behind like the electrical tape. Remove the pins once the paper sheet is firmly in place.

Step 5: Transfer the Bottom Layer

Now you can transfer the bottom layer onto the laminate. The procedure is the same as with the top layer. I add an additional sheet of baking paper to ensure the iron doesn't get glued to the tape.

After you remove the paper, clean the glue left over from the tape. I didn't which is why you can see copper residues where the tape was stuck.

If needed, now is the time to make final corrections with PCB marker.

Step 6: Etch!

Time to start etching. I use sodium persulfate. You need approx. 100 grams per 500ml of water. Dissolve the powder in water that's about 50 degrees celsius and etch in about 40-50 degrees.

In order to control the temperature, place a smaller container in a larger bowl. This way you can add a little boiling water to the larger bowl while maintaining stable temperature for etching. It will also ensure that if you need to increase temperature by adding hot water, you do not change the proportions of the sodium persulfate solution.

Stir the liquid when etching as this will speed up the process.

Once no more copper is visible, remove the toner with a sponge. You can use the same solvent as you did for the initial cleaning of the laminate.

Step 7: Solder the Vias

Your vias are not plated so you need to make sure they conduct signals. I use remainders of resistor legs, but you can use any conductive material, such as jumper wires. Solder on both sides of the board and cut the excess.

Step 8: You're Good to Go!

Drill the remaining holes and solder and connect the other components to finish your board.

You're done. Enjoy your new gadget!

Comments

author
dmwatkins (author)2015-10-03

Hmm... I was thinking about writing an Instructable on double-sided etching... but I think I like your method better!

I transfer the top, soak, remove paper, drill... Then I use a "light board" (or whatever it's called - a glass or plexiglass surface with a light shining up from underneath), place the PCB top down on it, and use the light shining through the holes to align the bottom layer...

Using pins sounds like a lot less work... I have to try that! Thanks!

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ArturS8 (author)dmwatkins2015-10-03

Interesting approach as well. How do you ensure the bottom layer stays in place after it has been aligned?

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dmwatkins (author)ArturS82015-10-03

I don't fully trim the board until after etching, so at this point I have a little extra space past the design to use tape. Normally I use painter's tape.

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JamesW440 (author)dmwatkins2017-06-11

The method of using pins is ok and I use it myself. But I have had trouble using the pins directly to the holes. By that I mean that if you put the pins through the marked holes, you are always off a little and it adds up. Plus if the mask is a little skewed, your dead.

I put the four holes in one of the masks and then use that to make the other set of holes in the second mask. Then drill the holes in the blank copper clad and check it against the copper clad and the back side. I had trouble with getting wrinkles if I didn't do it this way, ie, if I put the holes in the mask first and drilled the holes, they didn't match up perfectly and the alignment would get skewed.

See my comment previous.

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dmwatkins (author)ArturS82015-10-03

Oops, in the first comment I meant to say place bottom down on the light box. Paper design on the plexiglass, then board.

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MalteG1 (author)2016-12-05

Quick question. Do you use a UV light box before etching or do you just dump the PCB with masks on into the etching liquid?

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JamesW440 (author)MalteG12017-06-11

After the transfer process is complete, the masks must be removed, leaving the toner on the copper clad. This method does not use photosensitive boards, so no UV is involved. After the masks are removed, the boards are ready for etching unless one wishes to apply a Green covering to protect the toner from the etchant.

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JamesW440 (author)2017-06-11

Just FYI: I have tried the Toner Transfer Method several times and have been dissatisfied with the results each time. I used several different kinds of paper and found that the yellow paper available from Amazon worked best for me. It would transfer almost all of the toner - but the key words are 'almost all'. It seems like it is almost impossible for me to get a good quality image on the copper clad.

I did find that I could use paint pencils - they look like Sharpies but have paint in them. I used the ultra fine point which is approximately the same as the Sharpie fine point. They actually worked and don't etch off. If I were to hand draw a pattern that is what I would use rather than a printed transfer.

The biggest problem I have had is after finally acquiring a usable image, I cannot get the opposite side to align properly. I use offset alignment holes. The accuracy of the transfer sheets should be compared to regular paper printouts to assure that they are accurate. If the holes do not come within the pads of each other, you might have a problem with the printer you are using, which might require several attempts to get an accurate rendition to use. You might as well spend quite a bit of time with this alignment rather than have it offset so that they are misaligned. My printer has trouble holding the fine yellow paper and the misalignment is not really noticeable until you check it. Sometimes I waste several sheets to get one good pair.

You can check the alignment by laying the transfer paper over the corresponding plain paper side with a light behind it and see if they can be adjusted until all of the items on the board are correct. Take notice if either of the transfer sheets is out of alignment. Then lay the two transfer sheets over each other with a bright light behind. The holes should align. If they don't, you probably won't be able to get them right on the copper clad either.

The method to make the alignment to the copper clad is:

1. Stick four pins through the first side (I usually start with the front) through the sheet at the center of each alignment hole,

2. Remove all four pins

3. Align the backside onto the front side so that all of the holes are as near alignment as possible (simply holding it up to a fairly strong light is sufficient).

4. Press the pin through one of the front side holes (already punched) and then through the backside transfer paper. If things are right it should hit dead-center of the corresponding hole in the backside paper.

5. With the first pin in place, keeping the paper taut and holding the alignment, push one of the other pins through the existing frontside hole through the backside. Again the pin should pierce the backside paper the same as the frontside was.

6. Complete the remaining two holes using the same method.

7. Once the holes are in place, lay the top paper over the copper clad using the orientation that will be used for transfer, and mark the holes carefully into the copper - I use a sharpie so that it marks through the hole onto the board. It is good if you can make some kind of indentation on the board because the small drill bits want to wander.

8. Approach the hole marks carefully and slowly, and drill out the four pin holes the thickness of the pins - I use a drill size just larger than the pin diameter, approximately 0.8 mm as I recall. I believe the pins were 0.7 mm, but they fit quite snugly.

9. Lay the backside transfer paper over the backside of the copper clad to verify the fit. The holes should align and you should be able to place all four pins through without tearing the paper.

The only other question I had is what the order should be. If you drill the alignment holes in the copper clad before doing one of the transfers, then you risk damaging the transfer and need to fix them. I prefer to make the holes in the copper clad before the transfer. I pin the three together: backside, copper clad, and front side with overlapping edges on the frontside that are about 1/2" all around and the backside overlapping by 1" so that I can tape the two in place to each other after putting tape on the corners of the copper clad to the backside paper to hold the copper clad in place. As I indicated, the final step is to tape all along the top and the sides to completely encase the three pieces - then remove the pins.

The assembly can now be run through a laminator or an iron used to make the transfer without fear of tape offsetting the iron except at the very extreme corners. The method for iron use is to turn the iron to maximum, after it is fully heated, wrap the assembly with a heavyduty paper shop towel - one thickness on each side. The iron should be pressed down straight with the maximum amount of iron surface in contact with the assembly. Hold for a 15 count, rotate 90 degrees (same side) and press down as many times as it takes to totally cover the area of the board, counting 15 seconds on each press. Press with as much pressure as you can without breaking the iron or your arms.

Then repeat the same on the other side. I usually do this twice on each side total so that means flipping it three times. The board should get very hot.

After it cools completely, remove the paper per the instructions for the paper used. My experience with the yellow paper is that it practically falls off. If the assembly did not inside the taped area, the transfer will be perfect, but I have had lots of trouble when I tried to 'iron' it because it ends up shifting and the traces are messed up. One reason is that the paper changes size as it heats, another is the temperature is not controlled, another is the uneven pressure and time taken to do it. I have found that the highest temperature of my iron is barely acceptable, not the nylon setting or lower which didn't work at all (cheap iron).

Another transfer method is sheet vinyl. That worked quite well, but similar problems occurred with incomplete transfers. But it did as well as the yellow paper.

The main problem with the toner transfer is that the traces are not solid even though they look perfect. I have been able to overcome that with the Green sheets available on Amazon as well, but if the toner doesn't transfer, it won't work either.

I have purchased and modified an Amazon laminator to use for this purpose, but I am working on making photosensitive boards too as they appear to make more accurate transfers. I use regular laser printer transparencies and have a light board to provide UV at such a level that it takes about 1 minute to expose. The problems that I have experienced with it is that I can't tell in subdued light whether the development is completed.

Still looking for a better method. Hope this helps others who have been having problems.

Thanks for a good instructable!

author
ftuesday (author)2015-10-11

Nice instructable! What kind of drill press are you using?

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ArturS8 (author)ftuesday2015-10-13

Just a simple, inexpensive one from the local store. Looks like this

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amacias-1 made it! (author)2015-10-07

I made it, thanks for the tip :D

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MatthieuR (author)amacias-12015-10-11

Nice!

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ArturS8 (author)amacias-12015-10-07

Looks great!!!

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MikB (author)2015-10-10

"Small pieces of the toner may come off during drilling." -- is this because you are using active parts of the circuit for your alignment holes? There is a simple answer to that :- either add some sacrificial pads out toward the corners, or, use the mounting holes for your PCB as the alignment -- pilot drill them with the small diameter bit, use for alignment, and then later drill to full size. That way, if you damage any toner, it's on non-critical bits.

Nice method though!

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ArturS8 (author)MikB2015-10-10

Good point! If you want to put the PCB in an enclosure, you need mounting holes anyway. I included your tip in the instructable.

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ThomasVDD (author)2015-10-10

Very clever method! I'll give it a try :)

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marc.deloor.5 (author)2015-10-07

Nice one!

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qxfuse (author)2015-10-07

nice!

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SangeetS (author)2015-10-07

Good Idea.

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RogerT2 (author)2015-10-06

Awesome instructable!!! Thanks so much - Roger

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mfonte1 (author)2015-10-06

What kind of transfer paper do you use?

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ArturS8 (author)mfonte12015-10-06

I use 170g/m2 glossy satin photo paper

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dantistus (author)2015-10-06

Thank you for the instructible! In post-USSR space people use a simple software for designing PCBs called "Sprint Layout". It's freeware (at least I assume so), is really lightweight and easy to use.

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BlackoutXIII (author)2015-10-06

Great instructable; this will come in handy for some of my projects at home. Thanks for taking the time to create this doc.

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rocketman221 (author)2015-10-03

Some Kapton tape works really well for holding the paper on the
board. It doesn't melt and leave sticky residue behind like the
electrical tape.

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ArturS8 (author)rocketman2212015-10-05

Thanks for pointing this out. I included this tip in the instructable.

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Ryan MacKenzie (author)2015-10-03

I like your method of doing the via's

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bravoechonovember1 (author)2015-10-03

cool! I'm curious what the circuit is

author

Looks like a DHT22 in the top right corner (white), so i bet its something to do with temperature or humidty.

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ArturS8 (author)phall102015-10-03

Correct. It is a esp8266-based temperature, humidity, pressure and light level logger.

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DIY Hacks and How Tos (author)2015-10-03

Nice way to make a DIY PCB. It looks really good.

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