DESCRIPTION
WS 735 is an alcohol based, organically activated, water-soluble liquid flux designed specifically for wave solder applications. WS 735 may be applied by automated flux sprayers, foamed, dipped, or brushed on with favorable results. WS 735 is active at room temperature and maintains a wide activation range and exceptional wetting characteristics that produce bright shiny solder joints. WS 735 performs well with bare copper, solder coated, and organic coated pwbs. WS 735 may be utilized with tin-lead and lead-free solder alloys. Since WS 735 flux is still active post-processing, all residues must be removed from PCBs.
FEATURES
- ENHANCED ACTIVITY LEVEL
- EXCELLENT WETTING
- LEAD-FREE COMPATIBLE
- WIDE PROCESS WINDOW
- CAN BE FOAMED, SPRAYED, BRUSHED, OR DIPPED
- FOAM RESISTANT RESIDUES
* Passes IPC requirements, product testing results available upon request
PHYSICAL PROPERTIES
- SOLIDS CONTENT 23.1%
- FLUX DENSITY 0.997 +/-0.005
- ACID VALUE 63.6 ± 2
HANDLING
- WS 735 has an unopened shelf life of 12 months when stored at room temperature.
- Do not store near fire or flame. Keep away from sunlight as it may degrade product.
- WS 735 is shipped ready-to-use, no mixing is necessary.
- Do not mix used and unused chemical in the same container. Reseal any opened containers.
FLUX APPLICATION
- WS 735 is formulated for application via foam but may be sprayed, brushed, or dipped as well. Flux pots should be plastic or titanium.
- For spraying, WS 735 is ready to use directly from its container, no thinning is required. When spray fluxing, it is imperative that proper flux coverage and uniformity be achieved and maintained. A dry flux coating of 500 to 1500 micrograms per square inch is recommended as a starting point.
- When nitrogen sealed wave solder equipment is used, it is generally necessary to apply slightly more flux than normal as a result of excess drying, due to the extended length of the equipment.
- When foaming, air stones should be supplied with compressed air, free of oil and moisture. Adjust foam head to achieve a uniform distribution of small bubbles for optimum flux coverage.
- During foaming applications it is periodically necessary to add AIM’s Common Flux Thinner to replace that which is lost through evaporation.
PROCESS CONTROL
Specific gravity should be monitored and controlled either with an automated flux density controller, or anually with a hydrometer. Specific gravity should be maintained at 0.997 +/-0.005 for optimum performance. Dump and refill flux pot with fresh flux at least once per week when used daily.
For spray flux applications, ensure proper coverage of PWB is maintained.
THERMAL PROFILE
FLUX TECH-TIPS:-
PROBLEMS & POTENTIAL CAUSE
- BRIDGING: INSUFFICIENT FLUX, EXCESSIVE PRE-HEAT, EXCESS CONVEYOR SPEED, SOLDER CONTAMINATION
- SOLDER BALLS: LOW PREHEAT TEMPERATURE, EXCESS FLUX
- WHITE RESIDUE: EXCESS FLUX, FLUX CONTAMINATION, SOLDER CONTAMINATION
- DISCOLOURED JOINT: SOLDER OXIDATION, BOARD/COMPONENT CONTAMINATION, EXCESSIVE HEAT
CLEANING
WS 735 can be cleaned in normal tap water. Deionized water is recommended for the final rinse. A temperature of 100° - 150°F is sufficient for removing any residues and will produce MIL-F-28809 ionic cleanliness levels. An in-line or other pressurized spray cleaning system is suggested, but is not required.
