Product Description Kester FL250DS is a no-clean, air or nitrogen reflowable solder paste specifically designed for automotive requirements. FL250DS is compatible with post-soldering process chemicals, including conformal coatings and potting compounds. FL250DS is capable of stencil printing downtimes of up to 90 minutes with an effective first print at 20mils. FL250DS also has the capability of printing up to 200mm/sec (8in/sec) with squeegees or within an enclosed head.
Standard Applications 90% Metal -- Stencil Printing. 90% Metal ? Enclosed Head Printing.
Physical Properties (Data given for Sn63/Pb37,90% metal, -325+500 mesh) Viscosity (typical) : 1600 poise Malcom Viscometer @ 10 rpm and 25°C Initial Tackiness (typical) : 42 grams Tested to J-STD-005, IPC-TM-650, Method 2.4.44 Slump Test: Pass Tested to J-STD-005, IPC-TM-650, Method 2.4.35 Solder Ball Test: Preferred Tested to J-STD-005, IPC-TM-650, Method 2.4.43 Wetting Test: Pass Tested to J-STD-005, IPC-TM-650, Method 2.4.45
Recommended Reflow Profile
The recommended convection reflow profile for FL250DS formula made with either the Sn63Pb37 or Sn62Pb36Ag02 is shown here. This profile is simply a guideline. Since FL250DS is a highly active, no-clean solder paste, it can solder effectively over a wide range of profiles. Your optimal profile may be different from the one shown based on your oven, board and mix of defects. Please contact Kester if you need additional profiling advice.

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