Resistance welding flux is printed on PCB components before they are coated on plates. Its main function is to prevent “wiring” and short circuit during wave soldering and protect the PCB permanently. In addition, printing plants can also save solder, reduce the weight of printed circuit boards, reduce costs.
The soldering flux has the following properties: high temperature resistance, brazing temperature (260±2℃), in the specified welding time (5±2), no softening, no damage; Good electrical performance, surface insulation resistance should be greater than 1×10^ (3). Alcohol, acetone, banana water and other solvents. Has a certain wear resistance, in printing plates and other machine processing. The solder film should not be damaged. The colors are beautiful and even.
It can be divided into two types according to curing conditions: hot solid type and light solid type, hot solid type resistance flux, single component and two component. Single component modified epoxy resin, alkyd resin, amino resin, acrylic resin, polyurethane resin, melamine resin, silicone, epoxy resin as the main raw materials, add appropriate amount of pigment, fillers, curing agent, solvent, auxiliary materials, after grinding and processing.
A two-component thermal curing flux is a curing agent of imidazole or amine, namely solidified solid or liquid epoxy resins. UV-cured flux is a kind of solder resistance commonly used in printing plants. Its main components are: light solid resin, photosensitizer, thinner, pigment, leveling agent and thixotropic agent.
Photosolid resin is mainly composed of epoxy resin acrylate and its modifier, diluent and photosensitizer, mainly polyacrylate, generally benzene ether. This kind of flux is characterized by ultraviolet light irradiation in a certain wavelength range, the crosslinking reaction can quickly solidify the film. Usually does not contain volatile solvents, low temperature fast curing, can meet the requirements of mass production automation, high production efficiency, good product quality, heat curing flux about more than 10 energy
