Rosin flux is a type of soldering flux derived from rosin, a naturally occurring resin obtained from pine trees. It's a crucial component in soldering, acting as a cleaning agent and preventing oxidation on the metal surfaces being joined. This prevents the formation of oxides that would hinder the solder's ability to create a strong bond.
How Rosin Flux Works
Rosin, primarily composed of abietic acid and its homologs, is typically dissolved in a solvent like isopropyl alcohol for use as a flux. This creates a liquid that can be easily applied to the soldering joints. When heated during soldering, the solvent evaporates, leaving behind the rosin to perform its cleaning and protective functions. The rosin prevents oxidation by creating a barrier between the heated metal and the air.
Different Types of Rosin Flux:
- Type R Rosin Flux: This is the most basic form, consisting only of dissolved rosin and a solvent, without any added activators.
- Mildly Activated Rosin (RMA) Flux: Contains rosin, a solvent, and a small amount of activator to improve its cleaning ability. It's a more aggressive cleaner than Type R but still relatively low in activity.
Key Features of Rosin Flux:
- Non-corrosive: Unlike acid-based fluxes, rosin flux is generally non-corrosive, making it suitable for sensitive electronic components.
- Relatively Low Activity: This means it's less effective at cleaning heavily oxidized surfaces compared to more aggressive fluxes. However, for many soldering applications, this level of activity is sufficient.
- Residue: Rosin flux does leave behind a residue, though it's typically less of a concern than the corrosive residue left by acid fluxes.
Applications:
Rosin flux is widely used in various soldering applications, including:
- Electronics soldering (especially for sensitive components)
- Model railroading
- General metalworking
Examples of Rosin Flux Usage:
- Solder wire often contains a rosin core, providing the flux directly within the solder material.
- Rosin flux can be applied separately as a liquid or paste, using a brush or applicator.
Comparison to Acid Flux:
While rosin fluxes are less aggressive than acid fluxes, they are safer for sensitive electronics as they're non-corrosive. Acid fluxes offer superior cleaning power but require careful cleaning after soldering to prevent corrosion.
