Discussion About The SMT Solder Paste Knowledge

1. Composition and function of solder paste

The paste processed by the solder paste mixer is composed of flux and solder power.

1.1 The components and functions of the flux are as follows:

a.Activator: This component mainly plays a role in removing oxidized substances on the surface of the PCB copper film pad and the soldering part of the part, and has the effect of reducing the surface tension of tin and lead;

b.Thixotropic: This ingredient mainly adjusts the viscosity and printing performance of solder paste, and plays a role in preventing tailing and adhesion during printing;

c.Resins: This component mainly plays a role in increasing the adhesion of solder paste, and it also protects and prevents the PCB from re-oxidation after soldering; this component plays an important role in fixing the parts;

d.Solvent: This component is the solvent of the flux component, which plays a uniform role in the stirring process of the solder paste, and has a certain impact on the life of the solder paste.

1.2 Solder powder

Solder powder, also known as tin powder, is mainly composed of tin-lead alloy. When there are special requirements, there are also tin powders that add a certain amount of silver, bismuth, and other metals to the tin-lead alloy. The alloy composition of lead-free solder paste.

2. Solder composition and powder number and scope of application

Main components: tin Sn, lead Pb, bismuth BI, copper Cu, silver Ag

3. The characteristics of common solder paste temperature

4. Solder paste storage

The refrigeration temperature is 4-10 degrees Celsius and can be stored for about 6 months.

After taking it out, return to temperature for 4-6 hours.

Stir for 1-3 minutes before use, 60-80 revolutions per minute.

Try to use it up after taking out the refrigerator, and do not put the unused solder paste back into the refrigerator.

The ambient temperature during solder paste printing is 23-25 degrees Celsius, and the humidity is 45%-75%.

5. Use of solder paste

Stir the solder paste for 30 seconds. Pick up some three or four inches higher than the container. The solder paste will drip down by itself.  On the contrary, the viscosity is poor.