Alcohol-Based Wave Solder 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-9945
WF-9945 is a halogen-free no-clean flux developed for wave soldering mixed-technology and through-hole electronics assemblies. WF-9945 is formulated to provide excellent wetting and superior hole-fill under a wide variety of conditions. When compared to Indium Corporation’s halogen-free WF-9955, WF-9945 contains more rosin, which increases heat stability and widens the effective heat profiles, allowing for very high yield when wave soldering larger, thicker, and more complex circuit boards. The trade-off is slightly more visible residue and in some cases, changes required to electronic probe testing procedures. WF-9945 is designed for use with tin-copper, tin-silver-copper, and tin-lead alloys.
Features
- Halogen-free per J-STD-004B* To be halogen-free per J-STD-004B, the formula must contain less than 500ppm of any kind of halogen, ionic or nonionically bonded chlorine, bromine, or fluorine. This is new to J-STD-004B since fluxes that conform to the original J-STD-004 or J-STD-004A may still contain halogens that only disassociate at soldering temperatures, but leave a residue that contains ionic halogen.
- Light-colored, low-residue, and rosin-containing flux for better performance on large and thick circuit boards. Rosin, modified rosins, and resins contribute to enhanced heat stability for thick or difficult-to-solder boards and for the encapsulation of flux activators. However, in some cases, rosins and resins may interfere with electronic probe-testability.
- Compatible with Hot Air Solder Leveled (HASL), Immersion Silver, Electroless Nickel Immersion Gold (ENIG), and Organically Solder Preserved (OSP) Copper surfaces.
- 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.
Physical Properties
As received, Indium Corporation’s WF-9945 flux is light amber in color. This amber color is a result of more than one-half of the 5.77% flux solids being composed of amber-colored rosin or rosin derivatives. The balance of the flux is an anhydrous alcohol and aliphatic hydrocarbon blend having a flash point of 54°C. This solvent blend ensures even distribution of flux solids both during storage and during spray flux deposition. The specific gravity of WF-9945—0.796 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 quality control WF-9945. This is because flux solids content is relatively low and small amounts of water contamination can confuse specific gravity measurements. While in-process quality control of WF-9945 is not generally required, the best method to ensure both solids content and activity level is by acid value titration. The WF-9945 formula contains no ionic or nonionic halogenated compounds. The total halogen content, as shipped, is warranted not to exceed 50ppm.
| Test | Result |
| Specific Gravity @ 25°C (77°F) | 0.796 |
| Specific Gravity @ 15°C (60°F) | 0.802 |
| Acid Value mgKOH/g flux | 14.4 |
| Acid Value mgKOH/g flux solids | 249.6 |
| Solids Content | 5.77% |
| Flash Point (°F TCC) | 54 |
| J-STD-004B Flux Type | ROL0 |
Shelf Life
The shelf life for this product is 3 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 longest shelf life of an opened container, replace cap to reduce alcohol evaporation and store in a cool, dry environment.
Residue Removal Recommendations
All of Indium Corporation’s no-clean fluxes, including this formula, are designed to be electrically safe under normal consumer electronic and telecommunication operating conditions. Unless otherwise specified, electrically safe means that the post-soldering residues pass J-STD-004B SIR and ECM testing. However, it is understood that some customers desire to remove residues for cosmetic reasons, improved in-circuit testing, improved compatibility with specific conformal coatings, or where the operating parameters of the circuit board may be in extreme conditions for a prolonged period.
If the removal of no-clean flux residues is desired, most commercially available cleaning agents will be effective. Indium Corporation’s Technical Support Engineers work closely with cleaning agent vendors and have confirmed flux residue removal capabilities from several vendors using their recommended products and parameters. It is unlikely that users of Indium Corporation’s no-clean products will need to change their current residue removal materials and parameters from those currently used. However, when establishing a new process or desiring confirmation of process recommendations, please contact Indium Corporation’s Technical Support staff for assistance.
Indium Corporation Compatible Products
- Solder Paste: Indium8.9HF
- Cored Wire: CW-807
- Flux Pen: FP-500 (rosin-containing)
Indium Corporation’s wave soldering fluxes have been designed to be fully compatible with our solder paste, cored wire, and rework f lux, and are also expected to be compatible with many of our competitors’ products. For example, WF-9945 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 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.