How to correctly choose the right solder paste in SMT patches?

We all know the importance of solder paste to SMT patches. A good solder paste can make components better attached to the PCBA board and produce high-quality products. However, there are many types and specifications of solder paste in SMT patch processing plants. The solder paste used by the same SMT patch processing plant in SMT patch processing also has differences in alloy composition, particle size, viscosity, cleaning method, etc., and the price difference is also very large. How to choose the right solder paste in SMT patches has a great impact on product quality and cost.

It is generally recommended to combine the specific production environment and refer to the activity, viscosity, powder shape, particle size, and melting point of the solder paste for patch processing.

1. The alloy composition should be determined first when selecting solder paste in SMT patch processing. Alloy is the material that forms solder. It forms an alloy layer with the metal interface to be soldered. At the same time, the alloy composition also determines the welding temperature, so the alloy composition should be determined first. The alloy composition is mainly selected electronic products and processes. The alloy composition compatible with the welding should be selected as much as possible, and the process factors such as welding temperature should also be considered.

2. Reasonably select the flux in the solder paste of SMT patches. The printability and printability of solder paste mainly depend on the flux in the solder paste. Therefore, after determining the alloy composition in the solder paste, the flux that is suitable for the production process should be selected.

When selecting, its activity should be selected according to the storage time and surface oxidation degree of the printed circuit board and components: general products use RMA type; high-reliability products choose R type; printed circuit boards and components are stored for a long time, and the surface is severely oxidized. RA type is used, and it should be cleaned after welding.

3. Determine the ratio of alloy composition and flux in the solder paste of SMT patches. The ratio of alloy composition and flux directly affects the viscosity and printability of solder paste.

4. Select the viscosity of solder paste according to the process of applying solder paste and the assembly density of SMT patches. There are many ways to apply solder paste, and different application methods have different requirements for the viscosity of solder paste.

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