What is the difference between solder paste and flux?

Analysis of the difference between solder paste and flux

In the world of soldering, both solder paste and flux are indispensable "behind the scenes", and while they both assist in the soldering process, they are distinctly different in many aspects. Below, we will analyze the difference between the two in detail from multiple dimensions.

1. Appearance: intuitive distinction between liquid and paste

Flux is mostly in a clear and transparent liquid state, like a glass of pure water, with a light texture and good fluidity, and can easily spread on the surface that needs to be soldered.

Solder paste presents a paste-like form with a certain viscosity, similar to the ointment we use in our daily life, which is a kind of solid form, which allows it to stay in a specific position better when used.

2. Main ingredients and functions: unique focus on similarity

The main components of flux are usually rosin, but may also contain resins, halide-containing active agents, various additives, and organic solvents. Its core function is to remove oxides from the surface of the solder and the base metal being soldered, just like a thorough cleaning of these metal surfaces, while also preventing the surface from oxidizing again during the soldering process. Not only that, but it also reduces the surface tension of the solder, making it easier for the solder to adhere to the object being soldered, thereby improving the overall performance of soldering.

Solder paste also has the effect of removing oxides and reducing the surface tension of the material being soldered, which is similar to flux. Its composition also contains a variety of chemicals, but unlike flux, the composition of solder paste may be optimized for specific soldering needs. Moreover, solder paste has a certain adhesion force, which is like adding a "retaining lock" to the chip device, which can hold it firmly in the appropriate position. It can also be applied by printing dispensing, which is applied precisely only to the welding area, greatly improving the accuracy of use.

3. Usage method: the difference between the coordinating object and the operation method

The use of fluxis usually used in conjunction with the tin bar for welding, and throughout the soldering process, it is like a tacit partner, providing necessary assistance for the welding of the tin bar and ensuring that the welding work can proceed smoothly.

Solder paste is more commonly used for maintenance soldering and packaging of BGA and preset solder. Because it is in the form of a paste, it can be precisely controlled when applying in a local area, just like painting with a brush in a designated area, making it more convenient and flexible to operate and meet the welding needs of those who have extremely high requirements for the application position.

4. Application scenarios: each has its own focus on the distribution of fields

Flux has a wide range of applications, and it can be seen almost all in the soldering process of various electronic assembly processes. Whether it is the production of large electronic devices or the assembly of small electronic components, it can play a role in ensuring the stability of soldering quality.

Due to its unique paste-like form and function, solder paste is useful in some occasions that require extremely high welding accuracy, such as the welding of clocks and instruments, precision components, medical devices, and microelectronics and semiconductor precision devices. In addition, solder paste is widely used in the production of stainless steel crafts, the production of mobile communication equipment and digital products, the assembly of refrigeration equipment such as air conditioners and refrigerators, the processing of glasses and knives, the manufacture of automobile radiators, and the brazing of various PCB boards and BGA solder balls.

To sum up, there are differences between solder paste and fluxin terms of appearance, main components and functions, usage methods, and application scenarios. Therefore, when choosing to use, we need to combine specific welding needs and process requirements to select the most suitable auxiliary materials to achieve the best welding effect.