958 958 Low-Solids No-Clean Liquid Flux Low-Solids No-Clean Liquid Flux Product Description Physical Properties Kester 958 is a no-clean, non-corrosive, liquid flux Specific Gravity: 0.806 0.005 that is specifically designed for the wave soldering Antoine Paar DMA 35 25C of conventional and surface mount circuit board Percent Solids (typical): 2.7 assemblies. Kester 958 was developed to give Tested to J-STD-004, IPC-TM-650, Method 2.3.34 excellent soldering performance on bare copper printed circuit boards treated with OSP coatings. Acid Number: 23.2 1.0 mg KOH/g of flux Essentially, no residue remains after soldering. Tested to J-STD-004, IPC-TM-650, Method 2.3.13 Boards are dry and cosmetically clean as they exit the wave solder machine, thus posing no interfer- pH (10% solution): 3.1 ence with electrical testing. Kester 958 has excel- Hanna Instruments 8314 25C lent compatibility with most conformal coating products on the market today. This comprehen- Flash Point: 18C (64F) sive formulation possesses improved wetting characteristics and also exhibits superior corro- Reliability Properties sion inhibiting properties and provides a non- tacky residue. A major advantage of this flux is the Copper Mirror Corrosion: Low reduced odor associated with the soldering Tested to J-STD-004, IPC-TM-650, Method 2.3.32 process. Corrosion Test: Low Performance Characteristics: Tested to J-STD-004, IPC-TM-650, Method 2.6.15 Excellent for bare copper circuit board Silver Chromate: Pass technology Tested to J-STD-004, IPC-TM-650, Method 2.3.33 Compatible with conformal coat processes Improves soldering performance Chloride and Bromides: None Detected Reduced odor associated with soldering Tested to J-STD-004, IPC-TM-650, Method 2.3.35 process Eliminates the need and expense of cleaning Fluorides by Spot Test: Pass Non-corrosive tack-free residues Tested to J-STD-004, IPC-TM-650, Method 2.3.35.1 Classified as ORL0 per J-STD-004 SIR, IPC (typical): Pass Compliant to Bellcore GR-78 Tested to J-STD-004, IPC-TM-650, Method 2.6.3.3 Blank 958 PD 958 PU 9 9 9 Day 1 5.0 10 W 3.1 10 W 5.2 10 W 9 9 9 Day 4 6.8 10 W 5.810 W 4.9 10 W 9 9 9 7.2 10 W Day 7 6.3 10 W 5.5 10 W958 Application Notes Flux Application: Kester 958 can be applied to circuit boards by a spray, foam or dip process. Flux deposition should be 2 2 120-240 mg of solids/cm (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. Process Considerations: The optimum preheat temperature for most circuit assemblies is 90-105C (194-221F) as measured on the top or component side of the printed circuit board. Dwell time in the wave is typically 2-4 seconds. The wave soldering speed should be adjusted to accomplish proper preheating and evaporate excess solvent, which could cause spattering. For best results, speeds of 1.1-1.8 m/min (3-6 ft/min) are used. The surface tension has been adjusted to help the flux form a thin film on the board surface allowing rapid solvent evaporation. 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-20 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 4662 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 rede- posit on the circuit boards which may create a build up of residues on probe test pins. It is, therefore, nec- essary to clean the tank and then replenish it with fresh flux when excessive debris accumulates in the flux tank. Cleaning: Kester 958 flux residues are non-conductive, non-corrosive and do not require removal in most applications. Storage and Shelf Life: Kester 958 is flammable. Store away from sources of ignition. Shelf life is 3 years from date of manufacture when handled properly and held at 10-25C (50-77F). Health & Safety: This product, during handling or use, may be hazardous to health or the environment. Read the Material Safety Data Sheet and warning label before using this product. World Headquarters: 800 West Thorndale Avenue, Itasca, Illinois, 60143 USA Phone: (+1) 630-616-4000 Email: customerservice kester.com Website: www.kester.com Asia Pacific Headquarters European Headquarters Japanese Headquarters 500 Chai Chee Lane Zum Plom 5 20-11 Yokokawau 2-Chome Singapore 469024 08541 Neuensalz Sumida-Ku (+65) 6449-1133 Germany Tokyo 130-0003 Japan customerservice kester.com.sg (+49) 3741 4233-0 (+81) 3-3624-5351 customerservice kester-eu.com jpsales kester.com.sg The data recommendations presented are based on tests, which we consider reliable. Because Kester has no control over the conditions of use, we disclaim any responsibility connected with the use of any of our products or the information presented. We advise that all chemical products be used only by or under the direction of technically qualified personnel who are aware of the poten- tial hazards involved and the necessity for reasonable care in their handling. The technical information contained herein is consistent with the properties of this material but should not be used in the preparation of specifications as it is intended for reference only. For assistance in preparing specifications, please contact your local Kester office for details. Rev: 5March10