What is the difference between the PCB positive and negative output process?
The negative is because the film was produced, or to the surface of copper line is transparent, and not the part in black or brown, the line process after exposure, because the transparent part of light and chemical agent by the effect of hardening film resistance, developing process the next will take no hardening of dry film flush, so in etching only part of the dry film etching away copper foil (film black or brown, while retaining part) dry film is not flush part of our line (film transparent part), to the film after leaving we need line, in this process in the film the hole to cover the exposure and the film requires slightly higher, but the manufacturing process is fast.
Positive: we usually talk about the pattern process, the use of liquid alkaline etching
If the positive film, line or copper surface are black or brown, but not part is transparent, the same line after the exposure process, because the transparent part of light and chemical agent by the effect of hardening film resistance, developing process will take the next not hardened dry film away, then the process of lead tin, the tin lead plating in the former process (developing) dry film on the copper surface flush, and then go to the membrane action (for removal of light and hardened dry film), and in the next process in alkaline etching, no bite tin lead protection potion copper foil (film transparent part), the rest is what we are going to the line (film black or brown part). Custom Circuit Boards china