What characteristics should be noted when choosing lead-free solder paste? What is the significance of thixotropy for printing?

To a large extent, it can have a significant impact on the soldering effect of the chip. It is particularly important to choose a lead-free solder paste that matches the product features. The application characteristics of lead-free solder paste describe the performance of lead-free solder paste from various aspects. Then, when choosingLead-free solder pasteWhat characteristics should be noted at that time? What significance does the thixotropy of lead-free solder paste have for lead-free solder paste printing? The following solder paste manufacturer will explain it to you:

What characteristics should be noted when choosing lead-free solder paste?

Among the requirements and characteristics for lead-free solder paste, many of them are contradictory. For instance, to ensure long-term printability, high-boiling-point solvents must be used. In such cases, during reflow soldering, the risk of damage caused by solder beads is increased;For another example, in order to achieve a good weldability, the catalytic activity of the flux must be added. This may increase the corrosiveness of the residue after welding and bring about safety and reliability issues...

There is no doubt that it is almost impossible to fully and completely meet all the characteristic requirements. Therefore, when making specific selections, it is necessary to have a profound understanding and mastery of these contradictory aspects. By taking into account the detailed characteristics and application scope of the assembled products, the relevant requirements can be balanced in a compromise, thereby achieving better comprehensive application value.

Ii. What is thixotropy of solder paste?What is the significance of thixotropy of solder paste for effectively ensuring the quality of solder paste printed products?

1Thixotropic agents are used to endow solder paste with good thixotropy. That is to say, under specified shear force and temperature conditions, the viscosity can drop sharply, enabling the solder paste to smoothly open the template and have good demolding performance. However, after the shear force is removed, we can restore and thus ensure the high consistency of the solder paste. There is no doubt that the printing performance of the solder paste is largely determined by the thixotropic characteristics of the solder paste itself.

2The mixture of the above various types of auxiliary materials is determined by the consistency of the flux paste. High-viscosity solder paste can all form good printed shapes, greatly reducing the occurrence of collapse. However, it is not suitable for passing through the template, as it is prone to clogging holes or dragging wires, leaving hidden dangers for future reflow soldering, such as false soldering and stuttering. It is also very likely to have defects such as solder beads and short circuits.

3In high precisionSMTIn the process, not only should the solder paste be able to print a good shape, but also it should be able to smoothly pass through the small opening template. Moreover, the consistency of the solder paste should be before and after printing(4~8h)Maintain stability; otherwise, it will be difficult to ensure the safety and reliability of multiple prints. Especially for fine spacingSMC/SMDFor the printing, the flux paste must also be thoroughly stirred to effectively ensure that the consistency of the flux paste meets the quality requirements. Only in this way can the quality of the printed products be guaranteed.

4Nowadays, the main industrial thixotropic raw materials that can be used include hydrogenated castor oil, Carpa palm wax, etc.

So far, it is believed that most people have a comprehensive understanding of the properties that must be noted when choosing solder paste, and have fully understood the influence of solder paste thixotropy on the printing performance of solder paste. If you want to know more about how to choose solder paste and its performance, you can follow Shenzhen JJY, a technology innovation enterprise mainly engaged in solder paste, flux paste, solder powder and soldering.