10x Negative Dry Film Photoresist Sheets 6x8" for DIY PCB Prototype
It's easy to make supper fine prototyping PCB by using this film:1.Clean your board. Cut dry film a little larger than your board.2.This Photoresist has 3 layers, the top and bottom layers are clear protective layer, so at the first, you need remove one protective layer, the easy way is to use two small pieces of scotch tape. Then apply the middle layer on board.A-- Apply using a hot roll laminator. This is the easist and professional way to do it.B-- Apply using your hand. Starting from one corner and ending to the cross corner, use your palm to remove all air bubble between film and board, set the iron temperature about 130C, apply the hot iron down onto the film and PCB, pressing them both flat and putting them under pressure.3.Place your negative artwork over the rest protective layer.  Use a glass to press the artwork to the board snuggly, then expose to UV light source or under sunlight,the source of light should be at least 8" away from the artwork. The best exposure time is depends, but you can easy to recognize it: the color of film is changing from light blue to dark blue.4.Remember: you need NEGATIVE film developer, Remove the rest protective layer on the film, now only resist left on the board, develop board in developer solution that mixed by 1g developer powder with 100g(or 100ml) water (~1% by weight).  After 3 minutes take board out of developer and hold under running water to check,you can always place it back in the developer if needs more time.5.Etch board.6.After board etched, use Acetone to remove the film, you can buy Acetone from any store where selling paint, Acetone usually used thin paint.