How to Quickly Determine and Handle Fluctuating Solder Paste Viscosity?

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When viscosity fluctuates, first check whether storage and heat recovery were done properly - insufficient warming leaves water in the paste and abnormal viscosity. Inconsistent stirring time and uneven mixing also change viscosity. As shop temperature rises, paste thins; left exposed to air for a long time, the flux volatilizes and viscosity rises. First check ambient temperature and humidity and standardize the stirring process; if fluctuation persists, the paste may have degraded - sample it for printing and wetting tests, and scrap it directly if it fails.

When the viscosity of Solder Paste changes significantly, first check whether the solder paste is expired or improperly stored. If clumping or poor fluidity occurs during use, it may be a sign of abnormal viscosity.

Viscosity changes may be caused by temperature fluctuations. Solder paste is sensitive to temperature; unstable workshop temperature will lead to fluctuating viscosity. The temperature control system should be inspected regularly, and solder paste should be stored within the recommended temperature range.

After opening, prolonged exposure of solder paste will accelerate oxidation and affect viscosity. It is recommended to open only the required amount each time and use it up as soon as possible.

When using a viscometer, ensure the instrument is properly calibrated. Large instrument errors may lead to inaccurate measurement results. Regular instrument calibration is critical.

Uneven mixing of solder paste can also cause viscosity fluctuations. Thorough mixing should be performed according to standard procedures to avoid locally high or low viscosity.

Before switching to a new batch of solder paste, test whether its viscosity meets the requirements first. Different batches of solder paste may have performance differences, so advance verification is necessary.

If tailing or missing printing occurs during the printing process, it indicates that the viscosity may be too high. At this point, adjust the squeegee pressure or replace with a more suitable solder paste.

When the viscosity of solder paste is too low, it is easy to cause solder joint collapse or bridging. Check whether the solder paste composition is normal and control the printing parameters properly.

During daily maintenance, pay attention to recording the usage of solder paste and the trend of viscosity changes. Investigate abnormalities promptly to prevent problems from escalating.

Keep the work environment clean to prevent dust from mixing into the solder paste. Impurities will affect viscosity stability and increase the defect rate.