What is solder paste? Solder paste is the most basic bonding material used in PCB board assembly. Let's talk about the characteristics of solder paste.
Solder paste viscosity. In daily life, the concept of “thin” or “thick” is often used to describe the appearance characteristics of fluids, but in engineering, the concept of viscosity is used to characterize the viscosity of fluids. We all know that when the solder paste is printed on the steel mesh, the blade is used for shear stress, and the solder paste is applied to the stencil or the screen, and then penetrates into the pcb pad through the steel mesh hole. In addition to shear stress, factors affecting solder paste viscosity include solder paste rotation rate, solder powder content, solder powder particle size and temperature.
The temperature has a great influence on the strength of the solder paste, and the viscosity will decrease significantly as the temperature increases. Therefore, whether testing the viscosity of solder paste or printing solder paste, you should pay attention to the environment temperature. Normally when printing solder paste, the optimum environment temperature is (23 ± 3) °C, and the precision printing should be guaranteed by the printer's constant temperature system.
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