Description:
NC257-2 has been developed to offer extremely broad process windows for printing, wetting and pin-probe testing. The superior wetting ability of NC257-2 results in bright, smooth and shiny solder joints, and it has been specifically formulated to lower solder beading.
It also offers very low post process residues, which remain crystal clear and easily probed. This solder paste offers a chemistry developed for use in air reflow, as well as providing slump and humidity tolerances to extend the useable life in facilities where environmental control is not at its optimum.
Features:
- Broad Printing Process Window
- Low-Tombstoning
- No Head-in-Pillow
- Clear Pin–Probe Testable Residue
- 24 Hour Stencil Life
- Excellent Wetting
- Reduces Voiding Under Micro-BGAs
- 12-14 Hour Tack Time
- Low Solder Beading
Printing:
- Apply sufficient paste to the stencil to allow a smooth, even roll during the print cycle (a bead diameter of 12 to 16 mm (½ to ⅝ inch) is normally sufficient to begin)
- Apply small amounts of fresh solder paste to the stencil at controlled intervals to maintain paste chemistry and workable properties
- NC257-2 provides the necessary tack time and force for today’s high speed placement equipment, which will enhance product performance and reliability
- Snap-off distance = On Contact 0.00 mm (0.00”)
- PCB Separation Distance = 0.75-2.0 mm (.030-.080”)
- PCB Separation Speed = Slow
- Squeegee Pressure = 0.10-0.30 kg/cm (.6 - 1.7 lbs/In.) of blade
- Squeegee Stroke Speed = 25-50 mm/sec (1 - 2 In./sec)
- * Note: Recommended initial printer settings above are dependent on PCB and pad design
- Cleaning of your stencil will vary by application; however, it can be accomplished using AIM 200AX-10 stencil cleaner
Reflow Profile:
Two unique profile families are depicted below; both can be used in ramp-spike or ramp-soak-spike applications, and they each have similar reflow temperatures. The two profiles differ in where they reach their respective peak temperatures, as well as the time above liquidus (TAL). The shorter profile of the two would apply to smaller assemblies, where as the longer profile would apply to larger assemblies, such as backplanes or high-density boards. The shaded area defines the process window. Oven efficiency, board size/mass, component type and density all influence the final profile for a given assembly. These profiles are starting points, and processing boards with thermal-couples attached is recommended to optimize the process.
- THE RECOMMENDED REFLOW PROFILE FOR NC257-2 IS PROVIDED AS A GUIDELINE. OPTIMAL PROFILE MAY DIFFER DUE TO OVEN TYPE, ASSEMBLY LAYOUT, OR OTHER PROCESS VARIABLES. CONTACT AIM TECHNICAL SUPPORT IF YOU REQUIRE ADDITIONAL PROFILING ASSISTANCE.
- THE REFLOW PROFILE FOR THE Sn/Pb PASTES USING A VAPOR PHASE REFLOW OVEN:PEAK TEMPERATURE RANGE I S 230°C–245°C.
