Alcohol-Based Flux
The main advantage of alcohol-based fluxes is that they require less preheat to drive off the solvent prior to entering the wave. This allows assemblers to run smaller wave soldering machines at a higher throughput rate. It also reduces the concern about flux that has not been completely heated inadvertently transferring to the top side of the circuit board.
Fluxes that have high solids content, as well as higher amounts of halogen, tend to be more heat-stable and solder better with a variety of board types, sizes, and thicknesses. Fluxes with lower solids contents and no rosin tend to be easier to electronically probe-test and have less visually apparent residue. Halogen content is not necessarily an indicator of final circuit board reliability since halogen types vary and rosin in the flux will enhance an assembly's surface insulation resistance.
WF-9948 Wave Solder Flux
WF-9948 is a fourth generation high-performance no-clean wave solder flux designed for use with through-hole and mixed-technology assemblies. While only containing about 3.3% flux solids, WF-9948 is very heat stable and well-suited for selective soldering applications. It performs well with both tin-lead and lead-free solders. WF-9948 has been designed to pass all known reliability requirements, including J-STD-004B SIR and ECM. This modern flux is non-corrosive, compatible with probe testing, compatible with most conformal coatings, and does not contribute to detrimental circuit board insulation resistance degradation or electrochemical migration.
WF-9948 Features
- Passes J-STD-004B SIR and ECM requirements for ROL0
- Indium Corporation created WF-9948 by adapting Indium’s very popular WF-9940 flux to the J-STD-004B requirements
- Fast wetting halogen-free formulation
- Wide process window for soldering larger and/or thick circuit boards: The halogen activator allows for better soldering and heat stability with lower total flux solids than a comparable halogen-free formula
- More heat stable than rosin-free formulations: Tested compatibility with a wide range of selective solder operations
- Tested for use with all common lead-free and tin-lead alloys, including: SAC305, SAC105, SAC0307, silver-free tin-copper plus additive alloys, such as Indium Corporation’s Sn995, 96.5Sn/3.5Ag, 63Sn/37Pb, 60Sn/40Pb, and many others
- Tested compatibility with Hot Air Leveled (HASL), Immersion Silver, Electroless Nickel Immersion Gold (ENIG) and Organically Solder Preserved (OSP) Copper Surfaces
- Compatible with all spray fluxes
Physical Properties
The color of WF-9948 is light amber, which is representative of fluxes that contain rosin. The solvent blend ensures an even distribution of flux solids both during storage and during spray flux deposition. The specific gravity of WF-9948, 0.792 at 25°C, is measurably higher than that of pure isopropyl alcohol. However, in contrast to higher solids content fluxes, specific gravity is not the best method to assign quality standards for WF-9948. This is because the flux solids content is relatively low and small amounts of water contamination can confuse specific gravity measurements. While in-process quality control of WF-9948 is not generally required, the best method to ensure both solids content and activity level is by acid value titration.
| Test | Result |
| Color | Amber |
| Specific Gravity @ 25°C (77°F) | 0.792 |
| Specific Gravity @ 15.5°C (60°F) | 0.799 |
| Acid Value mgKOH/g flux | 14.9 |
| Acid Value mgKOH/g flux solids | 456 |
| Solids Content | 3.27% |
| Flash Point (°F TCC) | 54 |
| J-STD-004B Flux Type | ROL0 |
Shelf Life
The shelf life for this product is 2 years in an unopened container stored at less than 32.2°C (90°F). Shelf life for an opened container will vary depending on storage conditions, including open time, temperature, and humidity. For the longest shelf life of an opened container, replace the cap to reduce alcohol evaporation and store it in a cool, dry environment.
Indium Corporation Compatible Products
- Solder Paste: Indium8.9 or Indium10.1
- Cored Wire: CW-807
- Flux Pen: FP-500
Indium Corporation’s wave soldering fluxes have been designed to be fully compatible with Indium solder paste, cored wire, and rework flux, and are also expected to be compatible with many of Indium's competitors’ products. For example, WF-9948 Wave Solder Flux is not only compatible with Indium8.9HF Solder Paste, but also with our 5.2LS, 8.9 series, 92 series, and 10 series. Indium Corporation determines compatibility primarily by matching flux chemistry. However, a select number of the wave, reflow, and rework product combinations have been thoroughly tested to ensure that the combined flux residues meet the electrical and reliability requirements of IPC J-STD-004B. Please contact Indium Corporation Technical Support if you are interested in knowing about these fully-tested combinations.