What is PCB rosin process-- ONESEINE

What is PCB rosin process?

What is PCB rosin process-- ONESEINE

Rosin on PCB surface treatment, also known as flux, is a surface treatment done by PCB circuit board factories during the post processing of PCBs. Its function is to facilitate customer SMT and plug-in processing in the later stage. It is a product with low board formation and high efficiency. Early rosin technology was mainly used for single-sided PCB boards, with materials such as 22F, FR-1, CEM-1, etc. Mostly used for small home appliance circuit boards.

The rosin process has three main functions:

1. Remove the oxide film. The essence is that the substances in the flux undergo a reduction reaction, thereby removing the oxide film, and the reaction products become suspended slag, floating on the surface of the solder.

2. Prevent oxidation. After melting, it floats on the surface of the solder, forming an isolation layer, thus preventing oxidation of the welding surface.

3. Reduce surface tension, increase solder flowability, and help solder wet solder components

The above is what rosin process is and the application of rosin process. With the passage of time, the improvement of electronic products and new requirements, it will gradually be changed to a more environmentally friendly OSP antioxidant process.

The PCB rosin process refers to the application of rosin-based flux or a protective rosin coating on printed circuit boards to prevent oxidation and improve solderability. Rosin, a natural resin derived from pine trees, is widely used in electronics manufacturing due to its excellent fluxing properties and its ability to leave a non-corrosive, insulating residue that can either be left on the board or removed depending on the application.

In typical PCB assembly, the rosin process involves spraying or foaming liquid rosin flux onto the board before wave soldering or selective soldering. The flux removes oxides from copper pads and component leads, allowing molten solder to wet the surfaces evenly. After soldering, a thin, transparent rosin residue often remains, which protects the soldered joints from humidity and corrosion. This residue is generally safe to leave on the board for low-voltage applications, though some industries require cleaning with solvents like isopropyl alcohol.

For bare PCB fabrication, the rosin process can also be used as a temporary protective coating. After etching and before final surface finish, a thin layer of rosin is sometimes applied to prevent copper pads from tarnishing during storage or handling. Companies like ONESEINE have refined this process, offering rosin-based protection that balances cost-effectiveness with reliability. ONESEINE provides both rosin flux application services and rosin coating solutions for PCB manufacturers seeking a simple, no-clean option for standard electronic assemblies.

The rosin process remains popular because it is forgiving and has a long history of proven performance. However, for high-reliability or high-frequency boards, manufacturers like ONESEINE often recommend switching to low-residue or no-clean synthetic fluxes, as rosin can occasionally cause ionic contamination issues in sensitive circuits. Still, for general-purpose electronics, the rosin process is a dependable and economical choice.