How to etch Double sided pcb?

I am trying to etch my circuit on a double sided copper clad at home. After designing my circuit I took a print on tracing paper and used iron to get the trace on copper clad. When I used iron paper got shrunk and ink spread all over and some connections didn't even go to the clad. Is there any good and easy way to get the circuit on double sided copper clad before etching. As its a double sided pcb I also faced problems matching the pins on both sides. I constantly tried to make sure that the holes on both side are aligned but failed everytime.

• youtube.com/watch?v=au2ba5gWLWk Sep 27, 2015 at 2:15
• I remember using the drill holes to align everything. Feb 20, 2017 at 19:18

I've successfully done etched double-sided PCBs using toner transfer paper. This is not easy. Aligning it is a pain, but I recommend that you get some Kapton tape (because it can take the heat).

Make sure that the PCB you print out have some crosses (plusses) in each corner, so you can "easily" align them 'perfectly' up against the light. Note: This is not easy, because the toner transfer paper is slippery!

Start by printing the two sides out on the toner transfer paper (remember to print the bottom layer mirrored), then cut it, so there's approximately 1cm extra on all sides.

Now you make an envelope, where the printed sides will face the inside of the envelope. The envelope should be taped by using Kapton tape on for instance the left side and the top; only two sides.

Place the copper clad inside the envelope, so you now have a sandwich (don't eat it, though).

The envelope with the copper clad is placed on for instance a straight wooden board; make sure it does not bend in any way. Wood can take the heat we're going to apply.

Warning: The PCB will be HOT... Turn on the iron; when it is hot, you push down hard for approximately 6 seconds (you count, you don't have time to look at the clock), then you lift the iron, turn it 90 degrees, put it down and push hard for 2 seconds, lift, turn 90 degrees, push down 2 more seconds and repeat this action just once more. Using a tool, flip the PCB over and repeat the above action, subtract up to 2 seconds from the initial ironing if the PCB is still very hot. Remember: The PCB is HOT, don't touch!

Pushing down hard means: Use all your body weight. If the result is that the toner traces falls off here and there, then the timing is too short; you'll need to apply the push for a longer time. If the result is that the traces are too wide/shaky, then you've applied pressure for too long.

Fortunately, you can retry by cleaning the copper clad, but you really want to avoid that, because cleaning it is a real mess and takes a lot of time.

Make sure you align the sides of the "envelope" perfectly, though. It really pays off to make precise work here, because when you put in the PCB, the sides are going to misalign a little bit already. If they're aligned perfectly from the beginning, then the error will not be too bad.

My description depends on how hot your iron gets, it also depends on the thickness of your copper clad (I used 1.6mm, the standard thickness, but also 0.8mm). You'll have to experiment a bit, before you go for the real thing. I recommend making some simple printouts and simple envelopes containing 9 dots (top, middle, bottom, left, center,right), then you don't have to do too much cleaning while practicing.

• I did that and it worked really well not sure about the alignment though.. I'll drill the holes tomo let's hope its perfectly aligned or else I'll have to hit the reset button.. Again.. Lol Sep 27, 2015 at 19:12
• It's great to hear you succeeded. I hope the alignment is within an acceptable range. Since I found Jaco, I've not etched a PCB at home, since they allow me to place small orders (10 pcs of 25 square cm. cost around $13 +$6 for shipping).
– user87445
Sep 27, 2015 at 22:45

I use photo resist PCB with a UV lamp (those used for tanning kind of work, not really well but yeah).

A method I used before I got some more professional gear was to use a laser printer and clear printable foil (sorry don't know the correct English term for that). As the laser printer isn't able to print it dark enough on a single foil I used two for every side.

To keep the alignment between the two foils for one side, I align them and use the soldering iron to melt them together at some points around the PCB (quite close to the board outline actually), that way they can't move anymore.

To get the alignment between the top and the bottom right, I always print the board outline as well. As the PCB has a certain thickness, an old piece of the PCB is used as a spacing between the two double foils (cut the foils to be just a bit bigger than the board outline) and tape the foil to the old piece in a way that top and bottom are aligned. It takes a bit of practice, but it's not that hard.

Now you have an old piece of PCB with the top and bottom foil hanging from it. Next step is to take the new photo resist PCB, put it in between those two foils. If you only have a single side UV lamp (like most non professional are) you will have to put it under it on both sides. To prevent a misalignment during handling, you can tape your new PCB to the foil as well. You'll have to experiment with the time a bit, around 1-2 minutes per side worked for me.

I'm not able to take pictures of that right now, so I hope I could kind of explain how I do it.

• Photo resist PCB isn't an option for me as where I live photo resist PCBs are not available. But I still liked your idea of using soldering iron to melt the transparency (probably that's the word you were looking for) and stick it with PCB so that it doesn't move. I'll try it let you know how well it worked.. Sep 26, 2015 at 4:28
• transparency didn't work it shrinks on heating... I used blank photo paper (the one on which we used to get hard copies of photos in old times) and it works amazingly well.. Sep 26, 2015 at 18:59