Negative Dryfilm Photo Resist Instruction for PCB prototyping. #1
Cut a PCB to your preferred size. The copper surface must be completely clean.
Cut a piece of dry film with the size of your board.
Strip off one of the cover sheets which are primitively adhered to the dry film.
Adhere the film to the PCB. (Be careful of bubbles!)
Place a clean sheet ( a piece of cloth ) on top of the PCB and iron all over the sheet with approximately 110 degree Celsius heat. ( Be careful for excessive heat which could melt the film).
Check up the bonded dry film for bubbles. If there are any bubbles, pop the bubble with a pin and redo the previous step (step 5). The dry film will not be bonded to the PCB if there are any bubbles.
Now your PCB is laminated. Place a 100 watts light bulb twelve inches high over the PCB.
Place the artwork film on the PCB and put a clear glass on top so the weight of the glass makes the artwork and the PCB better adhered to each other. Illuminate the bulb for approximately 15 minutes.
Mix the developer powder with 200 cc of clean water and stir them until the developer and the water completely mixed.
Strip off the other cover sheet.
Clean the PCB with the developer by using a sponge to gently rub all over the PCB until the artwork completely showed up. Make sure there is no any unwanted dry film left behind.
Rinse the pcb with water and wait until it is dry.
Put the PCB into a bowl of PCB Etchant. Slowly shake the bowl until the excessive (unwanted) copper is completely etched. Rinse the PCB with clean water.
Put the PCB into a bowl of thinner. The film will get soften and be peeled off from the PCB. Rinse the PCB with clean water.
Drill the holes and clean up your new PCB.
From : http://www.warapcb.com/dryfilm.php