Views: 6 Author: Site Editor Publish Time: 2020-12-04 Origin: Site Inquire
The first piece of isoline SMT processing refers to the first surface assembly board that meets the welding quality requirements.
1. Welding of the first surface assembly board Place the surface assembly board that has passed the mounting and inspection on the mesh conveyor belt or chain guide rail. The surface assembly board slowly enters the furnace with the conveyor belt according to its set speed, and the temperature rises. Area, In the heat preservation zone, reflow zone and cooling zone, complete SMT patch processing and flow soldering. Take out the surface assembly board at the exit in time. Anti-static tape should be worn during operation.
2. Inspect the welding quality of the first surface assembly board (1) Inspection method The welding quality of the SMT patch of the first surface assembly board is generally inspected by visual inspection. According to the assembly density, select 2 to 5 times magnifying glass or 3 to 20 times microscope for inspection. (2) Inspection content a.Check whether the soldering is sufficient, and whether there are traces of insufficient solder paste melting during the SMT chip processing. b.Inspect whether the surface of the solder joints is smooth, whether there are hole defects, and the size of the holes. c.Check whether the amount of solder is moderate, and whether the shape of the solder joint is half moon. d.Check the amount of solder balls and residues. e.Check the defect rate of tombstones, virtual soldering, bridging, component displacement, etc. f.Also check the color change of the PCB surface. After the SMT patch is reflow soldered, the PCB is allowed to have a little but even discoloration. (3) Inspection standards
According to the corporate standards established by VIASION Technology Co., Ltd. or refer to other standards.At present, most SMT chip processing plants adopt IPC-A-610E implementation.
3. Adjust the parameters according to the welding quality inspection results of the first surface mount board a. When adjusting the parameters, the parameters should be adjusted one by one for easy analysis and summary. b.First, adjust (fine-tune) the speed of the conveyor belt, retest the temperature curve, and perform trial welding. c.If the welding quality cannot meet the requirements, adjust the temperature of each temperature zone until the welding quality meets the requirements.
