Homebrew_PCBs

On Sun, 13 Apr 2014 10:41:36 -0400, you wrote:

>Hello,
>
>What methods are being used for successful toner transfer to a double sided
>board using a laminator?

I use a half thickness board, then epoxy the top and bottom together
to get a board (using what I have for board stock) that is 0.043 or so
thick.

Advantage is that if you have a bad etch, you can redo one side before
assembling.

Use thick pins to align the boards, avoids wobble.

Use 1 hour epoxy to do the board joining, is more forgiving and allows
you to do several boards. I cover the board copper with masking tape
to avoid epoxy fingerprints on the board.

Harvey

>
>I've tried several different methods without much success. Keeping the two
>toner transfer sheets aligned to the two PCB sides while going through the
>laminator has been difficult at best. Single sided PCBs are okay with the
>laminator.
>
>I'm using Techniks "Press n Peel" blue sheets as the medium for
>transferring the toner to the PCB.

That won't make a difference for board alignment, or perhaps
shouldn't.

I used a strip of board as a leader, with the two sheets taped to either side of it.
For alignment hold them against a bright light and match the drill holes up.
If your laminator tends to pull on one side (one driven roller) it helps to put the stack in a folded piece of card stock.


Still dicey at the best of times, even if you get the alignment right there will always be dimensional distortion in a laser printer, and shrinkage of the paper.
Yes you can print on the same area, and pre-dry the paper before use, but If I had to do mostly double sided boards I am not sure if I would select toner transfer. The fiddling about kind of defeats the simplicity of it all.

ST