1. Difference between PCB positive and negative:
PCB positive and negative are the ultimate effects of the opposite manufacturing process.
PCB positive: where the line is drawn the copper of the printing plate is retained, where the line is not drawn the copper is removed.Top, bottom...The signal layer is positive.
PCB negative: where the line is drawn, the copper applied to the printing plate is removed. Where there is no line drawn, the copper applied is retained.Internal Planes (Internal power source/ground layer) (hereinafter referred to as Internal electric layer), for laying power line and ground line.The traversal or other objects placed on these planes are areas without copper, that is, the work layer is negative.
2. What is the difference between PCB positive and negative output process?
Negative: usually we say tenting process, which USES acid etching
After negative film because the film produced, lines or copper surface is transparent, not part of it is black or brown, after line process exposure, transparent part because of dry film resistance agent light chemistry hardening, the next development process will take no hardened dry film hedge, so just bite dry films in the etching process develop part of the copper foil (black or brown film part), and keep dry film wash it is not belong to us to line (transparent film), membrane after they left the line of what we need, in this process of film hole to hide, the exposure of request and requirement for membrane was a little higher,But the manufacturing process is quick.
Positive: generally, the process of pattern is described. The liquid used is alkaline etching
If the feature film, to line or copper surface is black or brown, and not part of it is transparent, in the same way after line process exposure, transparent part because of dry film resistance agent light chemistry hardening, the next development process will not wash it hardened dry film, followed by lead tin plating process, the tin lead plating in the previous process (development) of dry film hedge copper surface, and then make to membrane action (remove hardened dry film) due to light, and in the next etching process, using alkaline liquid bite off without the protection of a tin lead copper foil (transparent film),The rest is the line we want (the negative is black or brown).
3. What are the advantages of PCB positive film and what are the main applications?
The negative is used to reduce the size of the file and the amount of calculation.Places with copper do not show, places without copper show.This can significantly reduce the data and computer display burden in the stratigraphic power supply layer.However, the current computer configuration is not enough for this workload, I do not think it is recommended negative, easy to make mistakes.The pad is not designed to have a potential short circuit or something.
If it is convenient to separate the power source, there are many methods, the positive can be easily divided by other methods, there is no need to use negative.