Print positioning gadget for double-sided PCBs

Hi! Quite a cool idea, if it makes the work easier, it's a success, as I myself often make double-sided PCBs for my needs and sometimes feel that it would probably be better to order and wait than to do it myself at home. As for thermal transfer, I personally do it differently in double-sided boards. I print both sides of the PCB on chalkboard paper, with one print on just one side left longer and the other print on the same side cut shorter, so that there is the possibility of later gluing these prints together with a layer of toner to each other using kapton tape. I then separately dry the paper with the print on an iron until the toner starts to shine. After assembling and marking the holes under a light or on an old monitor matrix with the backlight on, I tape the two printouts together on one side. After this I have the paper ready for ironing. I cut out the PCB laminate along the contour, clean, dry and degrease it. Then on a piece of plywood prepared for thermal transfer I place a cotton cloth or other piece of cloth, on this I place a sandwich of the print and in the middle I put the laminate. Then I put another cloth on top and the PCB is ready for ironing. Unfortunately it sometimes happens that the holes after ironing diverge by about half a millimetre then I remove the toner from the board and the whole procedure flies again, or sometimes if the paper is inadequately dried then I get blisters which are then impossible to remove Such a fate unfortunately I tried to print on special yellow paper but this has a tendency to crack the toner when bending, I also tried the photochemical method but I think in this case is even more work and there is also the problem of the double-sided PCB holes. I also tried varnishing the laminate and burning the paint with a 5W laser, but the first tests turned out to be average, so I will still try this method.

Thanks for the response
I did my first attempts with positioning holes too. The next with positioning the corner of the print with the corner of the plate. In the second case it is easier to achieve good results (in my opinion). This jig makes it easier to align the corners. I use a laminator for ironing, so it's a slightly different technology compared to an iron.

I at one time developed my own method for making PCBs.
I modified an old HP laser printer by pulling its fuser outwards so that when printing, the paper bypassed it, so that the applied toner was not fixed.
The toner adhered well to the paper (I sometimes used laser printer film), so that the drawing could be accurately applied to the laminate without any problem.
Then, with the help of a brush on the other side of the paper, I gently tapped the drawing (toner) onto the laminate.
Finally, I heated the laminate to fix the toner.
If necessary, the operation could be repeated. The paper or film could be used several times.

I made my last double-sided board a very long time ago, but somehow it didn't cause me any problems. First I printed the tracks on a laser printer and chalkboard paper and folded them under the light to make the vias meet. I taped the three sides together to make an envelope, inserted the board inside, fixed it with tape so it wouldn't move inside and put it in the laminator. Some movement did occur, but it was minimal.

As I was recently making a double-sided PCB by my own efforts in the editor I copied the Top layer, reflected relative to the longer edge and moved it by the thickness of the laminate (1.6 mm I think). I got two drawings this way, where I only included Bottom in the base one. I bent the print at the edges and everything fitted together perfectly.
The paper needs to be thicker to avoid jitter and it's best to bend the free edges at the start.
Obviously a PCB design oriented to minimise connections between layers, especially under the DIP elements.

I know from experience that it is also a good idea to run a blank sheet of paper through the printer, for heating before printing proper. The paper I have shrinks about 1mm when heated on the printer. The phenomenon is already very limited by the second printing.

efi222 wrote:

Corner of plate and paper with print slightly cut so that there is a better fit between the sides and the frame.

As you are designing for corners you can make rounds.



You will be able to use tiles without chamfers.

Good point. The scribe angles have a similar dodge.

I also thought of this as the hardware was already in use So much so that even with the hole in the corner there will still be a slight protrusion at the start of this rounding. Alternatively, it can be refined.