What is the role of steel mesh in SMT production?

PCBA, as we often say, is to mount
components with specific electrical performance on PCB according
to the determined BOM, position number, etc. Then, soldering the ends of the components with solder
paste or using red glue to position the electronic component and then using wave
soldering to conduct them to form a set circuit board, achieve the initial circuit function, and achieve
certain performance requirements of the product to improve productivity.

SMT Solder paste and red glue

Solder paste and red glue are thixotropic fluids with a certain viscosity. The steel mesh is designed
and laser-cut according to the Gerber file of the PCB and certain rules. The solder paste is printed on
the PCB pad through the opened mesh holes (or the red glue is printed on the bottom of the front of the
component and fixed).

When the scraper moves forward at a certain angle and speed, pressure is generated to
push the solder paste to roll in front of the scraper, generating the pressure required for the solder
paste to be injected into the mesh or leak hole. The viscous friction of the solder paste causes shear
at the junction of the scraper and the stencil. The shear force reduces the viscosity
of the solder paste and allows it to be smoothly injected into the mesh or leak hole onto the pad on the
PCB.

SMT steel mesh

The SMT steel mesh is a particular precision fixture for printing solder paste or red glue onto
PCB pads or between pads to fix components and welding to form the electrical properties
set by PCBA.