Method of coating PCB with solder paste

Abstract

The invention discloses a method of coating a PCB with solder paste. The method concretely includes the following steps: after printing of a pad or through hole of a PCB is finished, adding a layer of bottom tin on the pad or the ring of the through hole corresponding to a place that needs welding through tin immersion of a tin furnace; making a steel mesh, wherein holes in the steel mesh correspond to the pad or the through hole of the PCB; coating the steel mesh with solder paste, making a scraper move in a balanced manner to fill the holes in the steel mesh, corresponding to the pad or the through hole of the PCB, with the solder paste on the steel mesh; and separating the steel mesh with the PCB after reflow soldering is carried out by a tin press for the PCB. The beneficial effects are that the thickness of tin needs not to be controlled during tin immersion of the PCB, the holes are disposed in the steel mesh and filled with the solder paste during a SMT process when the PCB is coated with the bottom tin so that the thickness of tin is controlled, the cost is not added, the quality is reliable, management and control is convenient, the yield rate of a finished product is greatly improved, and the method can be independent of skills of employees; and after solder paste is disposed in welding positions, standards for the thickness of tin immersion can be loose, and the yield rate of a PCB semi-finished product can be increased.

Description

technical field [0001] The invention relates to a method for solder paste on a PCB. Background technique [0002] In FOG technology, PCB is completed by tin pressing process in the manufacturing process, and the quality and reliability of tin pressing are directly related to the tin thickness of PCB board. In the traditional PCB board manufacturing process, the bottom tin of the soldering position is completed by dipping tin in a tin furnace, and the thickness control of the tin after dipping is obtained by the speed of personnel picking up and the pressure of hot air. Due to the operation proficiency of the staff and the problem of hot air pressure, it is difficult to accurately control the thickness of the dipped tin, and the abnormal tin thickness after dipping will lead to poor soldering of the module tin pressing process, which in turn leads to product reliability problems Leading to customer complaints, product returns and rework and related claims, greatly increasing...

AI Technical Summary

Problems solved by technology

Due to the operation proficiency of the staff and the problem of hot air pressure, it is difficult to accurately control the thickness of the dipped tin, and the abnormal tin thickness after dipping will lead to poor soldering of the module tin pressing process, which in turn leads to product reliability problems Leading to customer complaints, product return and rework and related claims, greatly increasing the production cost of the factory and reducing the competitiveness of the product in the market

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