Thanks to Harvey, DuWayne and Ancel for your replies.
For the moment, My PCBs are made with a CNC router. Unfortunately, in a short while, I won't any longer have access to it. Prior to going into tremendous tests, I prefer to prepare the ground...
This confirm that the substrate must be hot. The temperature is depending on a lot of factors and trials look to be the best way to proceed. One parameter at a time.
About the transparent film, I remember that there were several kinds of materials we were used to use when making slides. One time, a guy used the wrong one and wrapped the foil around the printer cylinder, it was completely stuck, what a mess ! So better to Double or triple check the printing temp cylinder as well as the film temp withstanding before putting it into the printer. !
Another idea went to my mind, inkjet printers use clay coated papers. Perhaps, they're the same as Harvey told about. Did anyone give a try to the inkjet paper ?
kind regards