Introduction to PCB board solder mask

A resistance solder pad is a solder mask that refers to the part of the circuit board that needs to be coated with green oil.In fact,this solder mask uses negative output,so after mapping the shape of the solder mask onto the board,the solder mask is not coated with green oil,but rather exposed with copper skin.Usually,in order to increase the thickness of the copper sheet,a solder mask is used to draw lines to remove oil,and then tin is added to increase the thickness of the copper wire.
Requirements for welding masks
Welding masks are very important in controlling welding defects in reflow soldering.PCB designers should minimize the spacing or air gap around solder pads as much as possible.
Although many process engineers prefer to use solder masks to separate all pad features on the board,the pin spacing and pad size of fine pitch components will require special consideration.Although solder mask openings or windows that are not partitioned on the four sides of GFP may be acceptable,controlling solder bridges between component pins may be more difficult.For BGA solder masks,many companies offer solder masks that do not touch the pads but cover any features between them to prevent solder bridges from forming.Most surface mounted PCBs are covered with solder masks,but if the thickness of the solder mask is greater than 0.04mm,the application of solder paste may be affected.Surface mount PCBs,especially those that use fine pitch components,require low profile photosensitive solder masks.
Work production
Welding mask materials must be used through liquid wet process or dry film lamination.The provided dry film solder mask material has a thickness of 0.07-0.1mm and is suitable for certain surface mount products,but it is not recommended to use this material for close range applications.