920-CXF Soldering Flux, Zero-Halogen, No-Clean, 1 Gallon
Kester 920-CXF is a zero-halogen, low-solids, no-clean organic flux designed for wave soldering conventional and surface-mount circuit board assemblies. This flux eliminates defects often experienced in surface mount assembly wave soldering operations with traditional fluxes. This non-corrosive and non-conductive flux has an extremely low solid content. There is essentially no residue left on the assembly after soldering. There are no residues to interfere with electrical testing and the expense of cleaning is eliminated. PCB assemblies are dry as they exit the wave soldering machine. The surface insulation resistance is higher than that provided by typical organic water-soluble fluxes. The electrical reliability of the assembly is assured. This flux formulation is suitable for soldering bare copper and solder-plated circuit boards. For optimum soldering performance, it is advised that bare copper boards be free of excessive oxides and other contamination.
Performance Characteristics:
- Essentially no residue left behind after soldering
- Eliminates expense of cleaning
- Boards are dry as they exit the wave solder machine
- Non-corrosive and halogen-free
- No surface insulation resistance degradation
- No offensive odors given off during soldering
- Classified as ORL0 per J-STD-004
RoHS Compliance
This product meets the requirements of the Restriction of Hazardous Substances (RoHS) Directive, 2015/863 for the stated banned substances.
Flux Application
920-CXF can be applied to circuit boards by a spray, foam or dip process. Flux deposition should be 120 to 240 μg of solids/ cm² (750 to 1500 μg of solids/in²). An air knife after the flux tank is recommended for the foam and dip application to remove excess flux from the circuit board and prevent dripping on the preheated surface when the foam or dip process is used.
Flux Control
Acid number is normally the most reliable method to control the flux concentration of low solids, no-clean fluxes. To check concentration, a simple acid-base titration should be used. The Kester PS22 Test Kit and procedure are available from Kester. The complex nature of the solvent system for the flux makes it imperative that Kester 4662 Thinner be used to replace evaporative losses. When excessive debris and contaminants accumulate in the flux tank over time, this may affect the soldering performance of the flux. Hence, it is necessary to clean the tank and then replenish it with fresh flux or dispose of the spent flux when applicable. During flux change, it is recommended to clean the reservoir applicator with isopropanol solvent.
Cleaning
Kester 920-CXF flux residues are non-conductive, non-corrosive, and do not require removal in most applications. If residue removal is required, call Kester Technical Support.
Storage, Handling and Shelf Life
920-CXF is flammable. Keep it away from sources of ignition. The shelf life is 1 year from the date of manufacture when handled properly and held at 10 to 25 °C (50 to 77 °F).