Technical Data SheetTechnical Data Sheet 951 Soldering Flux Low-Solids No-Clean Liquid Flux Product Description Kester 951 is a halogen-free flux designed for wave soldering conventional and surface mount circuit board assemblies. The extremely low solids content (2.0%) and nature of the activator system results in practically NO RESIDUE left on the assembly after soldering. Boards are dry and cosmetically clean as they exit the wave solder machine. There are no res- idues to interfere with electrical testing. 951 exhibits improved soldering performance to minimize solder bridges (shorts) and excessive solder defects. This flux is suitable for automotive, computer, telecommunications and other applications where reliability considerations are critical. 951 contains a corrosion inhibitor such that no corrosion products are formed when bare copper surfaces are exposed to humid environments. Performance Characteristics: Improves soldering performance Non-corrosive tack-free residues Classified as ORL0 per J-STD-004 Eliminates the need and expense of Compliant to GR-78-CORE cleaning RoHS Compliance This product meets the requirements of the Restriction of Hazardous Substances (RoHS) Directive, 2015/863 for the stated banned substances. Physical Properties Acid Number (typical): 14.3 mg Thinner: 110 Specific Gravity: 0.814 Anton Paar DMA 25C KOH/g flux Tested by potentiometric titration Percent Solids (theoretical): 2.0% Reliability Properties Chloride and Bromides: None SIR, IPC (typical): Pass Copper Mirror Corrosion: Low Tested to J-STD-004, IPC-TM-650, Method 2.6.3 Tested to J-STD-004, IPC-TM-650, Method Detected 2.3.32 Tested to J-STD-004, IPC-TM-650, Method Blank 951PD 951PU 2.3.35 10 9 9 Day 1 2.3 10 9.4 10 8.2 10 Corrosion Test: Low 10 9 9 Tested to J-STD-004, IPC-TM-650, Method Fluorides by Spot Test: Pass Day 4 1.3 10 7.8 10 7.5 10 Tested to J-STD-004, IPC-TM-650, Method 9 9 9 2.6.15 Day 7 9.8 10 6.3 10 5.8 10 2.3.35.1 Silver Chromate: Pass Tested to J-STD-004, IPC-TM-650, Method 2.3.33 Global Headquarters: 800 West Thorndale Avenue, Itasca, IL USA 60143 Phone: +1 800.2.KESTER Fax: +1 630.616.4044 Asia-Pacific Headquarters: 61 Ubi Avenue 1 06-01 UB Point, Singapore 408941 Phone: +65 6.449.1133 Fax: +65 6.242.9036 European Headquarters: Ganghofer Strasse 45, 82216 Gernlinden, Germany Phone: +49 (0) 8142 4785 0 Fax: +49 (0) 8142 4785 61 Asia Manufacturing: Hengqiao Road, Wujiang Economic Development Zone Suzhou, Jiangsu Province, China 215200 Phone: +86 512.82060807 Fax: +86 512.8206 0808 Website: www.kester.com Application Notes Flux Application 2 951 can be applied to circuit boards by a spray, foam or dip process. Flux deposition should be 120-240 mg of solids/cm 2 (750-1500 mg of solids/in ). An air knife after the flux tank is recommended to remove excess flux from the circuit board and prevent dripping on the preheater surface when used in a foam or wave application. Process Considerations The optimum preheat temperature for most circuit assemblies is 93-115C (200-230F) as measured on the top or component side of the printed circuit board. Dwell time in the wave is typically 2-4 seconds for leaded alloys and 4-8 seconds for lead-free alloys. The conveyor speed should be adjusted to accomplish proper board contact time with the solder. Then the preheat temperatures are adjusted to achieve the required preheat top board temperatures. In the event you need further direction on the setup of your wave soldering system, please contact Kester Technical Support. 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. PS-22 Test Kit and procedure are available from Kester. Control of the flux in the foam flux tank during use is necessary for assurance of consistent flux distribution on the circuit boards. The complex nature of the solvent system for the flux makes it imperative that Kester 110 Thinner be used to replace evaporative losses. When excessive debris from circuit boards, such as board fibers and from the air line build up in the flux tank, these particulates will redeposit on the circuit boards which may create a build up of residues on probe test pins. It is, therefore, necessary to clean the tank and then replenish it with fresh flux when excessive debris accumulates in the flux tank. Cleaning 951 flux residues are non-conductive, non-corrosive and do not require removal in most applications. I f residue removal is required, call Kester Technical Support. Storage, Handling and Shelf Life 951 is flammable. Store away from sources of ignition. Shelf life is 1 year from the date of manufacture when handled properly and held at 10-25C (50-77F). The cap must be in place when not being used. Health and Safety This product, during handling or use, may be hazardous to your health or the environment. Read the Safety Data Sheet and warning label before using this product. Global Headquarters: 800 West Thorndale Avenue, Itasca, IL USA 60143 Phone: +1 800.2.KESTER Fax: +1 630.616.4044 Asia-Pacific Headquarters: 61 Ubi Avenue 1 06-01 UB Point, Singapore 408941 Phone: +65 6.449.1133 Fax: +65 6.242.9036 European Headquarters: Ganghofer Strasse 45, 82216 Gernlinden, Germany Phone: +49 (0) 8142 4785 0 Fax: +49 (0) 8142 4785 61 Asia Manufacturing: Hengqiao Road, Wujiang Economic Development Zone Suzhou, Jiangsu Province, China 215200 Phone: +86 512.82060807 Fax: +86 512.8206 0808 Website: www.kester.com