How to make 2-sided Printed Circuit Boards

Step 3 Cut and Register Board Layers

Cut out your two layers. Leave at least 1/4" around the board on three sides. Leaving the other side longer is good.

Now, turn on the light box. Place the bottom layer facing up, and the top layer facing down. Line them up so that all the pads are aligned evenly. Then tape around the edges and draw a box outlining the board dimensions.

Take the two pieces of paper off the light box, and tape them down to a piece of copper board. Now, drill the registration holes. You should drill at least three holes in an asymmetric pattern around the edge of the box. The holes should go through the paper and the board. Un-tape the paper and board.

Comments

[Computerman29]

Hello All,

I had ZERO success with ANY toner transfer methods until I tried these two things together:

1) After scrubbing the copper board, drop it into the etching solution for a few seconds. Remove and rinse. Be careful not to touch the copper after it is dipped/rinsed.  It roughens up the surface and makes the toner stick much better. It also removes any oils and deep-down dirt that the scrubbing missed.

2) When repairing traces with a "sharpie", roast the board on your iron for about 30 sec. to make sure the "sharpie" ink is completely dry, then etch.

I use a beat-up HP Laserjet 6L, press-n-peel blue with my iron on about 3/4 full heat and moderate pressure, and get great results. Your millage will vary. Experiment a bit. It is probably different with photo paper, but try the above tricks. Good luck!

[tinygeek]

That's cool. I like the idea of quickly putting it in the etchant to clean it. Thanks for the tips!

[jeff-o]

I wonder, is it even necessary to drill the registration holes if the two sides of the pattern are already aligned using the light table?  As long as there's some overlap the board could just be slid in between the pieces of paper and fused as-is.

It might be necessary to use heat-proof Kapton tape, though.

[tinygeek]

There is a "fold over" method of registration. The two sides are printed next to each other and then folded around the board. This is just the way I find easiest, but to each, his own.

[jeff-o]

Hmmm, that might also work, but you have to factor in the thickness of the board.  For what I've got in mind, that may introduce too much error.

One further question, have you ever tried doing the toner transfer to both sides of the board at the same time?  I've only ever done it one side at a time and it tends to smudge the side that's already done.  I want to avoid that, too...

[tinygeek]

I've tried transferring both sides at once, but I find that hard to do with an iron. That tends to work better with a small pouch laminator, but I don't have one of those. The one time I did use one, it worked quite nicely. I've pretty much stopped experimenting with toner transfer since I started milling my boards, but I would imagine that if you had a jig to hold the board still and in the same place, you could do one side after the other without smudging.

[jeff-o]

 Well, I gave it a shot.  I'm happy to say that I achieved nearly perfect alignment with the top and bottom pattern - Hooray!  I did it by lining up the layers using a light table, then taping together three of the four edges.  Then I just slid the board between the layers and went at it with an iron.

The toner transfer itself could have been better.  Perhaps it was not heated enough, or some dust or fingerprints got on there.  Still, I should be able to repair the board with some etch resist pen.

[tinygeek]

Awesome. I'll have to try that if I etch again.