How to evaluate lead-free and environmentally friendly solder paste? What is the variation pattern of viscosity during the printing process?

Lead-free and environmentally friendly Solder pasteHow to evaluate and what is the variation pattern of viscosity during the printing process? Generally, the methods we use to evaluate lead-free solder paste include3This situation can be classified into high temperature, medium temperature and low temperature3There are various types and someLEDSome large-scale enterprises use high-temperature solder paste, while others use low-temperature ones. This can also reduce the costs of enterprises and has some negative benefits for this industry.

We can understand that the metallic compressive strength of low-temperature solder paste is insufficient. YesLEDProducts, especially those with solar cells, have potential safety hazards. JustLEDIf the lamp beads can withstand heat, it is recommended to use high-temperature solder paste, as this is also the actual effect of soldering!

Medium-temperature solder paste is okay and the hardness of the solder is also very high. But for high-temperature solder paste, why is it not recommended,Spot soldered with low-temperature solder paste will be relatively brittle and very prone to dropping parts, especially smaller onesLEDIf the LED beads are a bit larger, they will fall off relatively easily.

In order to better achieve the purpose of this assessment, we have decided to carry out a reasonable experimental design with statistical analysis. We select the variables to be evaluated for lead-free environmental protection solder paste-The fewer the number of variables, the lower the number of experiments to be operated.

The following four variables were selected: the shelf life after packaging and printing, the shelf life after surface mount technology, different production batch numbers of solder paste, and the flow back soldering environment. This variable was selected because it is crucial to our entire technical process. However, it is necessary for your respective processes The selection of variables should be changed.

while Lead-free solder pasteIt also has certain thixotropic properties. During the production of solder paste, volatile solvents are added, which is equivalent to continuously mixing the solder paste throughout the application process. Therefore, this solvent evaporates faster, making the solder paste thicker. There are three viscosity variation trends of lead-free environmentally friendly solder paste during the packaging and printing process:

1Viscosity increase - conversely, if the solvent in the secret recipe is highly volatile, it will become even drier.

2Reduced viscosity - If the volatile substances in the flux formula of the solder paste manufacturer are low, it will appear thinner and thinner.

3The viscosity first decreases and then increases(The slope of the tangent line is not significant)And maintain it for a long time - this kind of situation should be an idealized one. In other words, the proportion of flux components is just right.

As is often mentioned, lead-based production and processing have better weldability than lead-free ones, but lead-free production and processing have a better concept of the natural environment. Want to know about itSMTThere are other problems with solder paste in surface mount technology. We warmly welcome everyone to consult us. Let's learn and grow together at Shenzhen JJY Industrial High-tech Co., LTD.!