Will the properties of lead-free solder paste change after its expiration? Can it still be used?

Lead-free solder pasteAs is known to all, it is a kind of paste with certain viscosity. Without heating, electronic components can be initially pasted on the circuit board. Then, as the temperature is heated, various solvents volatilize and react, and the electronic components and the circuit board are soldered together for a long time. It is an indispensable soldering material in the surface mount printing industry. I believe many friends have purchased it. When we purchase lead-free solder paste, we will find that soldering enterprises all mark the production batch number and shelf life of the solder paste. So, what changes will occur to the solder paste if it is not used in time? Today, Shenzhen JJY Solder Paste Manufacturer will talk about whether lead-free solder paste can still be used after its expiration date. Will the characteristics change? The problem.

The reasons for lead-free solder paste to expire

First, let's get familiar with the active ingredients of lead-free solder paste. Only in this way can we better understand why lead-free solder paste expires. Solder paste is usually made by mixing tin powder with flux, and the safety and reliability of solder paste depend on these two raw materials. It also determines the service life of the solder paste, which is what we call the "shelf life", and the flux is an even more crucial link. The conventional lead-free solder paste can be matched according to the product quality of the flux3Moon6It has multiple validity periods such as months and one year.

Fluxes usually contain active agents, thixotropic agents, resins, organic solvents and other components, which take into account the functions of removing the oxide film on the surface of the solder pad, regulating the viscosity of the solder paste, enhancing the adhesion of the solder paste, and regulating the stability of the solder paste itself. And these components are constantly reacting whether you have opened and used them or not, even if you store them at the appropriate temperature. Therefore, after these ingredients have completely reacted, the solder paste expires.

Can lead-free solder paste still be used after its expiration date?

This needs to be checked to see how long the expiration date has passed. If it has just expired not long ago and the solder paste is only a little dry, add some new solder paste and stir it, and it can still be used with some concern. Because the shelf life filled in by the manufacturers is rather cautious, if the storage environment of the solder paste is suitable, the flux reaction is slow, and the solder paste still contains surfactants inside, after stirring with the surfactants in the new solder paste, it can still meet the soldering standards. Of course, we do not recommend that you continue to use it. After the expiration date, the performance of lead-free solder paste will definitely decline. If the product requirements are high, it may not meet the requirements after use, thereby affecting the product quality. This would be counterproductive.

If the lead-free solder paste has oxidized significantly, it means that the solvent components in the flux have reacted almost completely and lost their function. Such solder paste is highly likely to cause adverse reactions when used for soldering, leading to problems such as short circuits and faults in the products, which is extremely harmful. Therefore, never use expired lead-free solder paste just to save on solder paste money.

16For many years, JJY has been dedicated to the research and development, production and sales of solder paste, providing customers with a complete set of electronic soldering solutions. If you want to learn more about solder paste, please keep following JJY Solder Paste Manufacturer and leave a message online to interact with us.