Teaches you how to distinguish the positive and negative of PCB film

How to distinguish between positive and negative film, usually (without words) give you a line (copper skin), or green oil (resistance welding) PCB film you can't distinguish between front and back, character PCB movie is very well distinguished. Because the character is accepted, the word is positive, it is positive, the word is negative, it is the opposite.

There are two ways to distinguish between lines and green oil.

The first is to use characters to correct. Usually, there are positioning holes on the PCB film. You can find the front and back of the line and the green oil on the front of the character.

Second, in the absence of a character PCB film, use a PCB film knife to gently scratch the top or corner of the PCB film to see if it can be scratched. If it can be scratched, it is positive. Otherwise it is the opposite.

This distinguishes the production line from the oyster sauce. Finally, you need to find character PCB film, or sample data that appears in computer printing, or PCB film data.