The impact of many projects on solder masks and solder layers is unclear. It is to open the window itself, but only provides the paste layer. There is no solder layer. Some board engineers don’t look at the paste layer (note that this is used). This is a useless layer for the plant’s engineers and can cause window leaks. The following is a brief introduction to their differences.      The solder layer is used to control the area where the green oil (white oil) is not covered when the board is fabricated. For example, the position of the pad, some key signal test points and green oil are not covered to allow the pad to leak. If the pad location does not include a solder layer, the pad will be covered with green oil and you will need to wear off the green oil (white oil) for soldering.      The paste layer is supplied to a plate making factory to produce a wire mesh. The stencil is perforated regardless of where the adhesive layer appears. That is to say, this layer is not used to control the PCB, but is used to control the opening of the template. These openings are used to brush the solder paste and the location of the solder paste (solder paste) when producing SMT patches. It happens to be the position of the mat.