Negative process of PCB circuit board: Generally speaking, the tenting process is considered the negative process. The liquid used in this process is acid etching negative. After the film is produced, the desired circuit or copper surface is transparent, while the other part is black. In the circuit process, the transparent part is chemically hardened by the dry film resistance agent under the effect of light. The subsequent development process will wash away the dry film that has not hardened, so in the etching process, only the dry film will be removed to wash away part of the copper foil (the black part of the film), while the dry film will remain unwashed to belong to the line we want (the transparent part of the film).
The positive process of PCB circuit board refers to the pattern process, in which the solution used is alkaline etched positive. When viewed from the negative, the desired circuit or copper surface is black instead of the transparent part. After exposure through the circuit process, the transparent part is chemically hardened by the light of the dry film inhibitor. The next development process will take no hardened dry film, followed by a lead-tin plating process. The tin-lead plating in the previous process (development) of dry film covers the copper surface, and then through membrane action (removing hardened dry film) due to light. In the next etching process, using alkaline liquid bites off the unprotected tin-lead copper foil (transparent film), leaving the line (black part of the film) remaining.
The positive and negative processes are selected according to each company’s process:
Positive process (double panel): Cutting – drilling – PTH (also called thickening copper plating) – circuit line – second copper plating (graphics) then SES line (backing down tin film – etching – tin plating).
Negative process (double panel): Cutting – drilling – PTH (also called thickening copper plating) – circuit line (no 2nd copper plating) then DES line (etching – stripping).
When distinguishing the films, the master film and working film can be categorized as black film and yellow film, positive film and negative film. Generally, the master film is black and is mainly used for copying the workpiece. The working film, on the other hand, is also black and is mainly used for high-precision HDI boards or for cost-effective production of small-batch PCBs.
Differentiating the film surface, the glossy black film is the film surface, while the yellow film is the opposite. The film surface can be identified by scraping the film surface with a pencil or blade. Note when using yellow films: there are two kinds of smooth surface and dull surface, and the second kind is prone to oil surface indentation.
The negative film is used for direct etching, and the corrosion resistance after development is the line, which is directly etched with an acid etching solution. The positive film, on the other hand, is used for graphic electroplating and development of the line, leaving the role of corrosion resistance of the electroplating, mainly leading to tin plating.
The positive process of PCB circuit board refers to the pattern process, in which the solution used is alkaline etched positive. When viewed from the negative, the desired circuit or copper surface is black instead of the transparent part. After exposure through the circuit process, the transparent part is chemically hardened by the light of the dry film inhibitor. The next development process will take no hardened dry film, followed by a lead-tin plating process. The tin-lead plating in the previous process (development) of dry film covers the copper surface, and then through membrane action (removing hardened dry film) due to light. In the next etching process, using alkaline liquid bites off the unprotected tin-lead copper foil (transparent film), leaving the line (black part of the film) remaining.
The positive and negative processes are selected according to each company’s process:
Positive process (double panel): Cutting – drilling – PTH (also called thickening copper plating) – circuit line – second copper plating (graphics) then SES line (backing down tin film – etching – tin plating).
Negative process (double panel): Cutting – drilling – PTH (also called thickening copper plating) – circuit line (no 2nd copper plating) then DES line (etching – stripping).
When distinguishing the films, the master film and working film can be categorized as black film and yellow film, positive film and negative film. Generally, the master film is black and is mainly used for copying the workpiece. The working film, on the other hand, is also black and is mainly used for high-precision HDI boards or for cost-effective production of small-batch PCBs.
Differentiating the film surface, the glossy black film is the film surface, while the yellow film is the opposite. The film surface can be identified by scraping the film surface with a pencil or blade. Note when using yellow films: there are two kinds of smooth surface and dull surface, and the second kind is prone to oil surface indentation.
The negative film is used for direct etching, and the corrosion resistance after development is the line, which is directly etched with an acid etching solution. The positive film, on the other hand, is used for graphic electroplating and development of the line, leaving the role of corrosion resistance of the electroplating, mainly leading to tin plating.
