What are the reasons for lead-free solder paste drying out?

SaidLead-free solder pasteRelatively speaking, it will be more popular among people because as people increasingly pursue environmental protection, the emergence of lead-free solder paste can be said to meet people's environmental protection requirements. However, lead-free solder paste is not completely without drawbacks. One of the disadvantages of lead-free solder paste that everyone may know is that it dries very easily. Now, let's explain it from JJY solder Paste Manufacturer:

There are mainly two reasons for lead-free solder paste to dry out:

For instance, if the formula is not good, the temperature is too high, and the solvent evaporates quickly. If the humidity is too high, the solder paste will absorb water and react with the rosin in the solder paste, causing it to dry out. From the perspective of the formula, it is generally not due to the use of alcohols. There are indeed many solder pastes that use alcohols, but it seems that ethanol has never been seen. More often, ethers are used.

Second, it is said that the solvent in the formula of the flux in lead-free and environmentally friendly solder paste, if the flux used to produce solder paste is a volatile solvent, of course, the solder paste will gradually dry out during use. However, there are too many factors contributing to the drying of solder paste. The reasons for the instability of the flux system due to the drying of solder paste are as follows:

1Rosin is the second largest proportion in flux. If it is unstable, it will directly affect the stability of the flux. If rosin with poor thermal stability is used to make solder paste, it is prone to deterioration in a high-temperature environment, which greatly increases the possibility of the solder paste drying out.

2Solvents, such as alcohols, are used as solvents. Before the flux is made into lead-free solder paste, its viscosity may increase and it may dry out. To take an extreme example: If anhydrous ethanol is used (for an experiment), it can be said that the solvent is the main reason.

3Organic acids, antioxidants, active agents, etc., these substances are added in small amounts but can have a relatively significant effect. The soldering effect of lead-free solder paste directly depends on them

4Thixotropic agent, the addition amount of thixotropic agent is also not small. It plays the role of emulsifying flux in it, generating thixotropy through emulsification, ensuring that the solder paste can continuously restore thixotropy during use. If there is a problem with it and it affects thixotropy, it will of course have an impact on the viscosity of the solder paste. If the viscosity increases, you will feel that the solder paste has dried out, that is, it has become hard.

In fact, there are many factors that can cause lead-free solder paste to dry out. It's not just a problem with the flux itself. If there are issues in other links, such as poor formula, inappropriate environmental temperature and humidity, etc., they can all be the reasons for lead-free solder paste to dry out. Therefore, we should pay attention when using it, choosing it, or making it.

Shenzhen JJY Industrial Technology Co., Ltd. is located in Longhua, Shenzhen. Its main business isLEDType solder paste, lead-containing solder paste, lead-containing silver solder pasteSMTProduction, research and development, and customization of solder paste, leaded solder wire, lead-free and leaded solder rods, wave soldering rods, automatic soldering wires, etc. If you have any needs, please feel free to contact us.