VOC-free, no-clean soldering flux for selective soldering

1.Description:

SelectIF 2040 is a VOC-free and no clean soldering flux developed for selective soldering. The flux combines a wide process window in selective soldering with low residue formation.

SelectIF 2040 is suitable for soldering units with high thermal mass and

hence high temperatures and long process times. Due to its special composition, it leaves less residues after soldering than the conventional fluxes for selective soldering.

SelectIF 2040 tends to give low solder balling after soldering. The flux is compatible with lead-free and SnPb alloys. Additionally, the flux is absolutely halogen free, guaranteeing a high reliability after soldering.

2. Applying the flux

In selective soldering, the flux is usually being applied by a micro-jet nozzle. The correct amount of flux will depend on parameters like type of surface finishing, oxidation level, thermal mass of the board and component,...and soldering parameters like used alloy, soldering temperature and time, turbulence of the wave,... It should be the goal to apply as little as possible flux with good soldering results. In practice this optimal flux volume is being determined by trial and error or by copying values of similar boards/solder joints. Compared to most fluxes, SelectIF 2040 typically only needs about half of the flux volume.

3. Preheating and wave contact

In general a preheating is used to limit the temperature shock and to evaporate the solvent of the flux. It is advisable to have the water content evaporated before wave contact. A good preheating can promote through hole wetting. SelectIF 2040 has no lower limit for the preheating temperature. It is advisable to keep the preheating below 160掳C when possible.

In selective soldering the wave contact is mostly determined by good through hole wetting. This is influenced by the preheating, the thermal mass of PCB and component, the wettability of the finishes, the solidification point of the used alloy and the working temperature. Like the flux amount, in practice this is being determined by