Comparison of commonly used fluxes aggression on copper surface

Soldering is the process of joining two metals by the use of a solder alloy. Joining material such as copper and other materials used in electronics assembly rapidly oxidize upon exposure to air, moisture, and heat. Reliable solder connections can only be accomplished with truly cleaned surfaces. For this purpose are used fluxes in electronics assembly. Flux is a chemical cleaner which removes oxidation from metal surfaces - cleans surfaces that are going to be joined together to enhance wetting by solder in the molten state. On the other hand flux can cause problems with future reliability due to aggressive residues which have conducting or corrosive properties. There are varieties of fluxes available for many purposes and applications. The most common types of fluxes include: Rosin - No Clean, Rosin - Mildly Activated and Water Soluble. This article deals with observation of commonly used fluxes aggression on copper surface in electronics assembly during the reflow process. Ten types of fluxes were compared in our experiment. Measurement was carried on glass samples with copper vapor deposition. Determination of flux aggression on copper surface was based on the measurement of absorption of light on spectrophotometer.