What is the difference between the positive and negative PCBs?
1, the difference between the positive and negative PCB:
The positive and negative of the PCB is the opposite of the manufacturing process.
The role of the PCB positive film: no matter where the line is drawn, the copper of the printed circuit board is retained, and the place where no line is drawn is also removed. Signal layers such as the top and bottom layers are positive films.
The role of the PCB anode film: no matter where the line is drawn, the copper of the printed circuit board should be removed and the place where no line is drawn is retained. Internal plane layer (internal power/ground plane) (internal power plane) for arranging power and ground. Traces or other objects placed on these planes are copper-free areas, ie the working layer is negative.
2. What is the difference between PCB positive output and negative output process?
Negative film: Generally speaking, what we call the tent method, the liquid used is acid etching.
The negative film is because after the film is formed, the desired line or copper surface is transparent, and the unnecessary portion is black or brown. After exposure by the line process, the transparent portion is chemically affected by the dry film resist light. Hardening, the next development process will wash away the dry film without hardening, so only the dry film is etched away during the etching process to wash off part of the copper foil (black or brown part of the film), leaving the dry film film not flushing Drop our line (the transparent part of the film) and after leaving the film, we leave the required circuit. During this process, the film should be covered and the exposure requirements and film requirements will be slightly higher. Some, but the manufacturing process is fast.
Positive film: Generally speaking, we are talking about pattern processing, and the liquid used is alkaline etching.
If the positive film is in the form of a negative film, the desired line or copper surface is black or brown and the part is transparent. Similarly, after exposure by a wire process, the transparent portion is chemically affected by the light of the dry film resist. After hardening, the next development process will wash away the dry film without hardening, followed by a tin-plated lead process, tin-lead on the dry-coated copper surface of the previous process (developed), and then the film is removed. Take action (remove the light-hardened dry film), then in the next etching, use alkaline syrup to bite the copper foil (transparent part of the film) without tin-lead protection, and the rest is the line we want (negative ) film) black or brown part).