When Solder Paste hardens during use, first confirm whether it is caused by improper storage conditions or excessive usage time, and also consider the impact of changes in ambient temperature and humidity on solder paste performance. If the surface of the solder paste is found to be hardened while the interior still maintains fluidity, you can try to restore its uniformity by low-speed stirring.

For solder paste that has completely hardened and cannot be restored, it must be disposed of in strict accordance with the scrap process to avoid printing defects or poor soldering caused by forced use. At this time, it is necessary to adjust the solder paste procurement and inventory management strategy in combination with the production plan to ensure that the solder paste is used within the validity period.

In actual operation, if the solder paste hardens and then softens, you should first check the storage time of the solder paste after opening. Solder paste that has not been used for more than 48 hours tends to harden due to solvent volatilization. At the same time, pay attention to whether the workshop temperature is too high, as high temperature will accelerate the volatilization of the Flux in the solder paste, leading to an increase in its viscosity.

If the solder paste has moderate hardness and can be restored by slight stirring, it can continue to be used. However, it should be noted that the printing operation should be carried out immediately after stirring to avoid hardening again. At the same time, it is recommended to store the solder paste in a cool and dry place to reduce the time of contact with air, so as to extend its service life.

In the process of handling the hardening and softening of solder paste, special attention should also be paid to the angle and pressure settings of the squeegee. If the squeegee angle is too small or the pressure is too high, it will lead to uneven force on the solder paste during the printing process, further aggravating the hardening phenomenon. Therefore, the squeegee parameters should be adjusted according to the characteristics of the solder paste.

For production lines that frequently have solder paste hardening problems, it is recommended to regularly check the quality stability of the solder paste supplier and optimize the solder paste usage process. For example, adopt a method of small batch and multiple requisitions to reduce the risk of solder paste being exposed to air for too long.

In practical applications, the problem of solder paste hardening and softening is often closely related to other process parameters, such as printing speed, stencil aperture size, etc. Therefore, when troubleshooting problems, multiple factors need to be considered comprehensively, rather than relying solely on a single solution.

The storage conditions of solder paste must also strictly follow the standard operating procedures, such as avoiding direct sunlight, keeping away from heat sources, and regularly checking whether the solder paste packaging is sealed and intact, to prevent the performance of the solder paste from deteriorating due to the influence of the external environment.