Gas fluxBoth gas flux and solder paste are used in the production of electronic products, especially circuit boards. Since they are quite common, this mainly discusses the differences between gas flux and solder paste.

　　Gas flux:

An ideal flux should not only have chemical reactivity but also possess good thermal stability, adhesion, spreading ability, electrochemical activity, environmental stability, chemical functional groups and their reaction characteristics, rheological properties, and adaptability to general cleaning solutions and equipment.

Flux can be classified based on its composition into inorganic water-soluble flux, rosin flux, and organic water-soluble flux. Based on the type of residue cleaning, it can be divided into solvent-cleaning type, water-cleaning type, and no-clean flux. Due to environmental protection requirements and to improve electrical performance, most are now lead-free no-clean flux.

　　Gas fluxThe main functions can be summarized as "assisting heat transfer", "removing oxides", "reducing the surface tension of the material being soldered", "removing oil stains from the surface of the material being soldered and increasing the soldering area", and "preventing re-oxidation". Among these aspects, two key functions are: "removing oxides" and "reducing the surface tension of the material being soldered."

Solder paste:

Solder paste is used for soldering; it isolates air to prevent oxidation and increases capillary action to enhance wettability and prevent cold solder joints. Solder paste is a white crystalline powder with a content of 99.0%, an acid value of 0.5 mgKOH/g, and a melting point of 112°C. It is easily soluble in ethanol and isopropanol. It is widely used in organic synthesis and as an intermediate in pharmaceuticals, serving as a surfactant in the production of flux and solder paste. It has high resistance, strong activity, and plays a certain role in brightness and full solder joints.

Solder paste is used for soldering larger metal parts, such as kettles or tin buckets. When the soldering iron makes contact for a moment, the high temperature causes gas to be generated from the solder paste, quickly removing dirt from the surface of the metal being soldered. Therefore, it is relatively easy to 'tin', but it also poses significant hazards as it is acidic and corrosive to surrounding metals.