New no-clean, low solids liquid fluxes from Heraeus ready to use in air and nitrogen wave soldering applications

Citation

(1999), "New no-clean, low solids liquid fluxes from Heraeus ready to use in air and nitrogen wave soldering applications", Soldering & Surface Mount Technology, Vol. 11 No. 1. https://doi.org/10.1108/ssmt.1999.21911aad.012

New no-clean, low solids liquid fluxes from Heraeus ready to use in air and nitrogen wave soldering applications

New no-clean, low solids liquid fluxes from Heraeus ready to use in air and nitrogen wave soldering applications

Keywords Flux, Heraeus, No-clean, Soldering

Heraeus has released two new, ready-to-use, no-clean liquid fluxes: Surf 11, a water-based, low solids, VOC-free flux that offers a high performance environmentally-friendly alternative to alcohol-based fluxes; and Surf 26, a traditional solvent-based flux that can be applied by spray, foam and wave.

Surf 11 features a special activator blend that ensures a very wide processing window, and consequently, is ideal for a wide range of applications in through hole and mixed technology assemblies. Unlike competing products, this is a ready-to-use formulation which can be applied in standard wave soldering equipment and is suitable for either air or nitrogen solder baths. After preheat and soldering, a very small amount of residue remains that is dry, non-tacky and not visible to the naked eye. Most importantly, such residues do not impede post-wave in-circuit testing, which can be carried out without any prior cleaning. However, if desired, residues can be cleaned using aqueous systems without any danger of white residues remaining after cleaning.

Water-based, Surf 11 is VOC-free, non-flammable and completely Halide free, offering an environmentally-friendly alternative to alcohol-based fluxes that are currently used in the industry. Advantages include a significantly improved atmosphere inside and outside the factory (no alcohol or IPA odour) as well as reduced costs in fire prevention and health and safety needs.

A high-performance solution, Surf 11 provides excellent wetting with Sn/Pb, Ni-Au and protected Cu surfaces. The flux also passes all Bellcore requirements for no-clean fluxes per TR-NWT-000078 as well as IPC criteria for class 3 (high reliability) no-clean fluxes to IPC-SF-818.

Application of Surf 11 can be either by spray or foam. For rework and testing purposes, the flux is also available in spray bottles. After application to boards by foam, it is recommended that the surplus be removed with an air knife. In a properly adjusted spray, there will be no surplus flux. After some time, in foam applications, the flux may concentrate due to water evaporation. Based on acidity values, dilution to the appropriate level must be made by adding de-ionised water. The level of acidity can be measured using the Heraeus acid value titration kit.

Halide-free, Surf 26 is a low-solids, no-clean liquid flux that can be applied by spray and foam. In a spray application dilution is not required as there are no evaporation losses. Foam applications may require the occasional addition of thinner, to dilute the flux due to excess solvent evaporation after some time in use.

Dilution of the Surf 26 flux to the appropriate level must be made using the specially formulated thinner WFT26. A simple test to measure acidity is used to determine how much thinner is needed. This can be carried out using the Heraeus acid value titration kit, which includes simple graphs to make calculations easy.

During the foam application there is the likelihood of moisture being present in the air line. This means the flux will absorb water, which within reasonable limits (up to 5 per cent) will not affect performance.

For further information, please contact: Mr Quentin Reynolds, Heraeus Materials Ltd, 1 Craven Court, Canada Road, Byfleet, Weybridge, Surrey KT14 7JL, UK. Tel +44 (0) 1932 349 315; Fax: +44 (0) 1932 347 904; E-mail: QReynolds@aol.com