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Solder Paste Printing is an important part of the SMT (Surface Mount Technology) process. Since solder paste is a mixture of powder and flux, it is in liquid form during printing. Viscosity (solder paste viscosity) is a key indicator of the liquid form of the solder paste. If it has low viscosity, it flows easily to fill and collapse. If it has high viscosity, it is easy to roll, peel and shape. The viscosity requirements are also different at different stages of the solder paste printing process. SMT has flexible viscosity requirements but fortunately, the viscosity itself is a variable that is easy to change. This changing viscosity requirement depends more on the solder paste printing process and printer parameter settings.
In a solder paste printer, the solder paste printed is sometimes very thin, resulting in product damage due to too little solder paste remaining after the oven finishes heating. This is why this is so important.
MALCOM SPIRAL VISCOMETER PCU-285
Viscosity range 5Pa・s ～ 800Pa・s / Speed range (N) 1～50rpm
Viscosity meter MALCOM PCU-285 are used and all give different numbers. Furthermore, the viscosity of a solder paste is highly dependent on the shear rate, so you need to know the specific shear rate (and equipment configuration) the manufacturer used. Worse still, since solder paste is a “non-Newtonian” fluid, viscosity is not the only parameter we need to deal with. Ultimately, the viscosity that works best for Paste A may not work best for Paste B.
In general, however, what you can do is monitor the batch-to-batch viscosity variation as reported by the manufacturer and relate it to your measured viscosity (which can be quite different) and/or your production performance.
If you see a lack of correlation for a batch, for example: the manufacturer reports a medium viscosity, you measure a low viscosity, and your manufacturing process shows evidence of defects or process indicators traceable to the low viscosity adhesive, then you have reason to suspect that batch.
At Semiki, we provide customized quotes to your exact specifications, ensuring high quality and reliable solutions for your manufacturing and industrial needs.
Solder paste quality control should be part of your overall quality control strategy towards a zero-defect manufacturing process. Finding a defect after printing or reflowing is too late, as reprinting or reworking is costly and can potentially impact the reliability of the assembly. Tight quality control of not only the solder paste but all materials in the manufacturing process is critical to ensuring the reliability of final assemblies.
Contact SEMIKI For SMT measurement solutions, genuine and highest quality solder paste viscosity measuring equipment.
SEMIKI Measuring Equipment Company Limited
Email: sales@semiki.com
Phone: +84 9797 61016