What is the difference between flux and solder paste? How should one generally make a choice?

Solder materials are indispensable in the production and maintenance work of the electronics industry. During the use of soldering irons, we often use them. Solder paste---Paste-like viscous body, mainly composed of metal powder, rosin, organic acid, thixotropic agent and active agent. ForSMTWelding in the automatic mounting process. Flux andSolder pasteWhat is the difference between them? Now, let's have the editor of JJY explain it to you:

Flux can also be called rosin or flux paste. Both belong to flux. The most important function of flux is to enhance the penetration effect between the welding material and the object to be welded during electric welding(If the infiltration is not good,The solder wire cannot effectively adhere to the object to be soldered, resulting in a spherical shape,It is very easy to weld empty).
There are also others such as removing air oxidation, assisting in heat conduction, reducing the interfacial tension of metal materials, and making spot welding look elegant and decent. Flux is classified into three major categories: the first is inorganic flux, the second is organic chemical flux, and the third is rosin. So what are the differences between them and how should we choose?

Difference:

1The raw materials are different:

Rosin

Solid pine epoxy resin, the raw material for making flux. The key assistance is to remove the metal oxides on the solder layer in the soldering of circuit board components, which is beneficial to the soldering of solder.

Flux

It is an auxiliary material for welding, but flux is composed of rosin, surfactants and some additives, and is produced and processed on the basis of rosin. It has stronger performance and is more powerful than rosin.

Solder paste

A thick paste-like substance, mainly composed of metal powder, rosin, organic matter, thixotropic agent and surfactant. For useSMTWelding of fully automatic surface mount technology. It is an upgraded substitute for flux and soldering processing technology, with a high level of automation technology and high-precision soldering.

2Corrosion is different:

The cleaned surface will effectively attach solder. This is also due to the fact that, in addition to surface surfactants such as rosin, the solder paste contains corrosive components. By using mild erosion to completely clean the surface, the solder can be attached very well.

Rosin is merely a simple surfactant that enables the solder to fully penetrate the soldering surface.

3The melting points are different:

The melting point of flux is much lower than that of solder raw materials.
      When we are welding, the flux will melt before the solder raw material and quickly cover the surface of the welding material, which has the effect of preventing the surface of the metal material from oxidizing. It can react with the surface oxide film of the solder at a higher ambient temperature, causing it to dissolve and restore the pure surface of the metal material.
      Flux is generally a mixture mainly composed of rosin and serves as an auxiliary material to ensure the smooth completion of the entire welding process. Soldering is the entire process of specific processing techniques in the installation of electronic components. Flux is the auxiliary material used during soldering. The primary function of flux is to remove metal oxides from the surfaces of the soldering material and the base material to be soldered, so as to achieve the required cleanliness on the surface of the metal material. It avoids the re-oxidation of the surface during welding, reduces the surface support force of the welding material, and enhances Welding performance. The performance of flux immediately affects the quality of digital products.
The specific active components of rosin are rosin acid and sea rosin acid, which are generally neutral. Liquid rosin has certain vitality, shows poor acidity and alkalinity, can react with metal oxides on the surface of metal materials, convert into chemical substances such as copper rosin acid, and float on the surface of solder. Moreover, it is corrosion-resistant and has strong insulation performance when in use. Generally speaking, rosin is the most common and best flux.
      After we understand this difference and effect, we should have a clear idea in our hearts. Apart from this, everyone should also accurately grasp the qualification certificates of the dealers. If necessary, you can visit the manufacturer's factory. If it is not a professional flux manufacturer, they are very afraid of this.

Shenzhen CityJJYCarry out mutually beneficial cooperation with electronic raw material producers, and also produce solder wires, solder rods, solder pastes and flux pastes for other enterprises. With a rich variety of successful cases in the research and development of chemical raw materials, our overall strength has created a sales market that is of high quality and honest and trustworthy.