Solder paste thickness control requirements and the causes of solder paste printing defects and countermeasures for improvement

Product management industry dynamic solder paste thickness control requirements I, solder paste thickness control requirements Solder paste thickness detection methods are: online detection ( detection) two-dimensional three-dimensional offline detection detection frequency: the first piece, 1 time / half an hour detection point operation document must stipulate (at least 5 points sampling) offline detection of solder paste thickness must be statistically analyzed, calculate CPk solder paste thickness control value (recommended control range): upper limit of solder paste thickness = steel mesh thickness + 20% ~ 30% Steel mesh thickness note: the lower limit of the thickness of the solder paste with a small value of the thickness of the steel mesh = the thickness of the steel mesh - 0.01 Second, the causes of the printing defects of the solder paste and the cause of the improvement of the countermeasures The cause of the defect Analysis Of the improvement countermeasures The amount of solder paste is too much, the printing thickness is 1. The scraper pressure is too small, and the solder paste is more.

 1. Adjust the scraper pressure. 2. The gap between the network board and the PCB is too large, and the amount of solder paste is too large. 2. Adjust the clearance. Solder paste tip, tin surface uneven steel mesh separation speed is too fast to adjust the steel mesh separation speed and demoulding method of tin 1.Solder paste itself problems 1.Replace the paste 2.PCB pad and steel mesh opening alignment is not allowed 2.Adjust the alignment of PCB and steel mesh, adjust X, Y, θ. 3. The printing machine support pin position is set improperly 3. Adjust the support pin position, so that the support strength of the tin position increases, reduces the deformation of the PCB, and ensures the printing quality 4. The printing speed is too fast, destroying the thixotropic agent inside the solder paste, so the solder paste becomes soft, that is, the viscosity becomes lower 4. The printing speed is less than 1. The printing pressure is too large, the separation speed is too fast 1. Adjust the printing pressure and separation speed 2. The solder paste placed on the screen is too long, the solvent volatilizes, and the viscosity increases 2. Replace the fresh solder paste 3. The steel mesh hole is blocked, the lower tin is less than 3. The mesh plate hole is cleaned 4. The steel mesh design is poor 4. The steel mesh design is changed 5. The solder paste is not added in time, resulting in less than the amount of tin 5. The appropriate amount of solder paste is added in time, and a good solder paste control method is used to control the printing interval time and the amount of solder paste added The causes of the printing defects and the improvement countermeasures