The light painting process is a very important part of the PCB in the circuit transfer process. Any errors that occur in this link may bring serious problems to the subsequent process, so each step inside must be strictly controlled. The photoplotter process can determine various process parameters according to user requirements.
The photoplotter process requirements are as follows:
1. Different requirements of the subsequent process to determine whether the PCB photolithography film is mirrored. The principle of film image: the film surface is attached to the film surface to reduce the error. If it is a screen printing process or a dry film process, the surface of the substrate film is attached to the copper surface of the substrate. If it is exposed with a diazo film, since the diazo film is mirrored when it is copied, its image should be such that the film surface of the film is not attached to the copper surface of the substrate. If the PCB is painted as a unit negative, rather than on a PCB-printed negative, an additional mirror is required.
2. Determine the parameters for the expansion of the solder mask.
Determining the principle: 1 large can not expose the wire next to the pad. 2 small can not cover the pad.
The solder mask may deviate from the line due to errors in operation. If the solder mask is too small, the result of the bias may cause the pad edges to be masked. Therefore, it is required that the solder mask should be larger. However, if the solder resist is expanded too much, the side conductor may be exposed due to the influence of the deviation.
3. According to whether there is a printed plug (commonly known as gold finger) on the board of the photoplotter to determine whether to add the process line.
4. Determine whether to add a conductive bezel for electroplating according to the plating process requirements.
5, according to the requirements of hot air leveling (commonly known as spray tin) process to determine whether to add conductive process lines.
6. Determine whether to add the center hole of the pad according to the drilling process of the photoplotter.
7. Determine whether to add a process positioning hole according to the subsequent process.
8. According to the appearance of the board of the photoplotter, determine whether to add a shape angle.
9. When the user's high-precision board requires high line width accuracy, it is necessary to determine whether to perform line width correction according to the production level of the factory to adjust the influence of side erosion.
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