I am currently designing a PCB to make with the toner transfer method for the first time. I was reading a guide that said to mirror the image before printing it to the paper. However it seems that the paper should not have a mirror image because when you are designing the board it is like looking through the board onto the other side and in turn drawing directly on the paper. Does the PCB design need to be mirrored to work?
For the toner transfer method, you should reflect the layout of the tracks of the top layer. When designing, the tracks of the top layer, they look like should be on the board. If you print as you see, the transfer will be reflected on the board. For this reason, you must reflect the print of the tracks of the top layer, but not the tracks of the bottom layer.