Many kinds of production raw materials are used in SMT patch processing. The tinnote is the more important one. The quality of the tin paste will directly affect the welding quality of the SMT patch processing. Choose different types of tinnuts. Let me briefly introduce the common tin paste classification:
Weld paste is a kind of pulp to mix the weld powder with a paste -like welding agent (rosin, diluent, stabilizer, etc.) with a welded function. In terms of weight, 80 ~ 90%are metal alloys. In terms of volume, metal and solder accounted for 50%.
Figure 3 Ten paste granules (SEM) (up)
Figure 4 Specific diagram of tin powder surface cover (down)
The solder paste is the carrier of tin powder particles. It supplies the most suitable flow degeneration and humidity to promote heat transmission to the SMT area and reduce the surface tension of the liquid on the weld. Different ingredients show different functions:
1. Classification according to the ingredients of tin paste
1. Lead welding paste: contain leading components, which is harmful to the environment and human body, but the welding effect is good and the cost is low. It can be applied to some electronic products that have no requirements for environmental protection.
2. Lead -free welded paste: The component is environmentally friendly and has a small harm. It is used in environmentally friendly electronic products. With the improvement of environmental protection requirements for environmental protection, lead -free technology in the SMT processing industry will become a trend.
2. Classification according to the melting point of tin paste
Generally speaking, the melting point of tin paste can be divided into three types: high temperature, medium temperature, and low temperature.
The commonly used high temperature is SN-G-CU 305, 0307; medium temperature has SN-BI-AG; low temperature commonly used SN-BI. In SMT patch processing, you need to choose according to different product characteristics.
3. Divided according to the fineness of tin powder
According to the diameter of the particles of tin powder, the tin paste can be divided into pinks of 1, 2, 3, 4, 5, and 6, of which 3, 4, and 5 are the most commonly used. The more precise products, tin powder needs to be smaller, but the smaller the tin powder, corresponding to the oxidation area of the tin powder will increase. In addition, the round tin powder will help improve the quality of printing.
No. 3 Fan: The price is relatively cheap, often used in large SMT processes;
No. 4 Fan: Commonly used in the processing of tight feet IC and SMT chips;
Fan 5: It is often used for very precise welding elements, mobile phones, tablets, etc., and high requirements for high -requirements; the more difficult it is to process the product of the SMT patch, the more important the choice of the sacotic paste. Help improve the process of SMT patch processing.
Post time: Jun-21-2023
