In recent decades, in the soldering process of electronic products, rosin resin fluxes mainly composed of rosin, resin, halide-containing activators, additives and organic solvents are generally used. This type of flux can be soldered. Good performance, low cost, but high residue after welding. The residue contains halogen ions, which will gradually cause problems such as electrical insulation performance degradation and short circuit. To solve this problem, the rosin resin system on the electronic printed board must be assisted. Flux residues are cleaned. This will not only increase production costs, but the cleaning agent for cleaning rosin resin flux residues is mainly fluorochloro compound. This compound is a depletion substance of the atmospheric ozone layer, which is banned and eliminated. Still. The process used by many companies belongs to the aforementioned process of using rosin tree finger-based flux solder and then cleaning it with a cleaning agent, which is low in efficiency and high in cost.
The main raw materials of no-clean flux are organic solvents, rosin resin and its derivatives, synthetic resin surfactants, organic acid activators, corrosion inhibitors, co-solvents, and film-forming agents. Simply put, various solid components are dissolved in various The liquid forms a uniform and transparent mixed solution, in which the proportions of various components are different, and their roles are different.
Organic solvents: one or a mixture of ketones, alcohols, and esters. Commonly used are ethanol, propanol, butanol; acetone, toluene, isobutyl ketone, ethyl acetate, butyl acetate, etc. as liquid components Its main function is to dissolve the solid components in the flux to form a uniform solution, so that the components to be welded can be evenly coated with an appropriate amount of flux components. At the same time, it can also clean light dirt and oil on the metal surface.
Natural resin and its derivatives or synthetic resin
Surfactants: halogen-containing surfactants have strong activity and high fluxing ability, but because halogen ions are difficult to clean, the ion residual degree is high, halogen elements (mainly chlorides) are highly corrosive, so they are not suitable for use The raw material of no-clean flux, halogen-free surfactant, has slightly weaker activity, but less ion residue. Surfactants are mainly fatty acid or aromatic non-ionic surfactants, and their main function is to reduce solder The surface tension generated when it comes into contact with the lead metal, enhances the surface wetting power, enhances the penetration of the organic acid activator, and can also act as a foaming agent
Organic acid activator: It is composed of one or more of organic acid dibasic acid or aromatic acid, such as succinic acid, glutaric acid, itaconic acid, o-hydroxybenzoic acid, sebacic acid, pimelic acid, apple Acid, succinic acid, etc. Its main function is to remove the oxide on the lead pin and the oxide on the surface of the molten solder. It is one of the key components of the flux
Anti-corrosion agent: reduce the residue of solid components such as resin and activator after high temperature decomposition
Co-solvent: prevent the tendency of activator and other solid components to de-solve from the solution, and avoid poor non-uniform distribution of activator
Film-forming agent: During the soldering process of the lead pin, the applied flux precipitates and crystallizes to form a uniform film. The residue after high-temperature decomposition can be quickly solidified, hardened, and reduced due to the presence of the film-forming agent. viscosity.