SMT Steel Mesh Wiping Roll Production Process

The SMT stencil wiping paper product looks like a very simple product on the surface. From its name, it is just a kind of wiping paper. From its function point of view, it is only used to wipe excess tin. However, the production process of this product is very complicated, at least the following three open network production process requirements:

First, the thickness of the opening

In order to have a good solder joint, it is necessary to properly print the solder paste steel mesh for the SMT stencil wiping paper. The PCB of different coated pads needs to be designed with different mesh thicknesses. For example, the thickness of the gold-plated pad PCB board and the bare copper PCB board network needs to be 0.13 to 0.114 mm. The thickness of the soldering pad PCB board subnet is 0.12 to 0.13 mm.

Because the tin-plated board has already immersed the tin molecules on the surface of the copper, the solder paste thus printed will be reduced, so that the tin beads between the two pads of the component will not be generated, so when the tin-coated board is opened. It is required to reduce the thickness of the PCB by a bare copper and gold-plated nickel alloy by 0.1 mm.

Second, the way of processing the network and the impact of its use

The steel mesh of SMT stencil wiping paper is generally processed by laser and corrosion polishing. The advantage of the laser network is that the hole wall is smooth and tidy, and the printing success rate is relatively high, and the disadvantage is that the small pitch is slightly deformed and the price is relatively high. The advantage of the corrosion polishing net is that the deformation of the small pitch is small and the price is relatively low, and the disadvantage is that the hole wall is not smooth, and the success rate of the small hole printing is very low.

Third, the mesh

The component mesh of the SMT stencil wiping paper is 100% equal to the pad, which is beneficial to the diffusion of tin. Larger components require anti-bead slots to prevent component soldering from creating solder balls between the two pads. The multi-PIN IC has the same vertical hole opening direction as the printing direction by 5 to 8 percent, because the deformation of the printing knife will make the solder paste with the same vertical hole as the printing direction more than the horizontal hole. The soldering direction of the printing direction is related to the length of the IC hole of the multi-PIN, which needs to be extended by 5 to 8 to increase the solder diffusion.