Core Functions of Lead-Free Flux
2026-07-31 00:00:00
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Introduce lead-free flux functions to remove oxide and improve solder joint reliability
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Lead-free flux is an essential functional chemical auxiliary for electronic soldering processes. It can be classified into solid, liquid and gaseous types by form. Its core functions include heat conduction, removal of metal surface oxides, reduction of substrate surface tension, degreasing, expanding soldering area and preventing secondary oxidation under high temperature. Removing oxide layers and lowering surface tension are the two primary functions.
Rosin serves as the main active ingredient of lead-free flux, which will be decomposed by molten solder at approximately 260℃. Strict control of solder pot temperature is required during actual production. Excessively high temperature will impair soldering quality. The four core functions of lead-free flux are listed as follows:
1、Dissolve and remove oxide films on base materials
Metal substrates continuously form oxide layers upon long-term exposure to air. These layers hinder solder wetting and lead to poor soldering. Spraying lead-free flux reduces and dissolves oxide films, purifies soldering interfaces and creates conditions for reliable soldering.
2、Isolate air to prevent secondary oxidation of substrates
High soldering temperature accelerates metal oxidation. Liquid flux evenly covers substrates and solder surfaces to form a dense protective film, isolating air, restraining re-oxidation of base materials and solder at high temperature, and keeping soldering interfaces clean.
3、Reduce surface tension and improve solder wettability
Molten solder features high surface tension, which tends to agglomerate and spread poorly. Lead-free flux reduces the surface tension of molten solder, enabling even spreading of solder, improving wetting performance and joint bonding effect.
4、Protect substrates and stabilize soldering qualityHigh soldering temperature may damage surface protection of substrates and trigger corrosion and oxidation. After cooling, high-quality lead-free flux forms a stable protective film on circuit boards to shield solder joints, lower risks of oxidation and corrosion, ensure firm solder joints and improve the soldering reliability of electronic products.
