Description:
WS353 SN100C® water soluble solder paste has been developed in response to electronics manufacturers demand for an all-purpose, reliably consistent water-soluble solder paste. WS353 SN100C® offers extended stencil life and tack time, robust environmental tolerance and printing characteristics, excellent activity, a broad cleaning process window, and compatibility with both tin-lead and lead-free solder alloys.
WS353 SN100C® can be used in fine pitch printing applications and has proven effective in the assembly of 0201 components. WS353 SN100C® provides consistent printing characteristics and slump resistance during high-speed printing. The excellent activity of WS353 SN100C® makes it a suitable choice when soldering to standard or difficult-to-wet parts, including lead-free alloys and finishes. In addition, WS353 SN100C® has proven to substantially reduce voiding under micro-BGAs. The residues of WS353 SN100C® may be cleaned easily in straight water, with the result being exceptional electrical reliability. In addition, WS353 SN100C® is designed to not foam during washing, even in high-pressure wash systems.
Features:
- Broad Printing Process Window
- Excellent Wetting
- Easily Cleaned Residues
- Lengthy Stencil Life and Tack Time
- Reduces Voiding Under BGAs
- Low Foaming during Washing
- Halide-Free
Paste Application:
- Apply sufficient paste to the stencil to allow a smooth, even roll during the print cycle (a bead diameter of ½ to 5/8 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. WS353 SN100C® provides the necessary tack time/force for today’s high-speed placement equipment.
- Ensuring proper support of PCBs during assembly and handling will enhance product performance and reliability.
Printing:
- Snap-off distance = on contact (0.00”)
- PCB Separation Distance = .030-.100”
- PCB Separation Speed = Slow-Medium
- Squeegee Pressure =1-1.7lbs/ In. of blade
- Print Speed .5
- 4 inches per second
Reflow Profile:
RTS Profile Guidelines:
- The typical rate of rise for the RTS profile is .9 – 1.2°C/second.
- The profile should be a straight line or concave; it should not be convex.
- Peak temperature is 240 - 250° C.
- Time above liquidus is 60 ± 15.
- The total profile length should be between 3.5 – 4 minutes from ambient to peak temperature.
- Cool down should be controlled within 4° C/second.
Paste Tech Tips:
- Problems and Possible Causes: - Bridging - Excessive solder, pad component solder ability, alignment
- Solder Balls - low Preheat temperature, oxidized or excess paste, too rapid initial ramp up
- Tomb Stoning - excessive delta temperature, rapid heat rate, component to pad mismatch, paste registration
- Discolored Joints - excessive peak temperature, board paste component contamination, excessive soak time
- White Residue – Solder paste oxidation, excessive time at temperature
- Beading – Excess solder paste, component placement
- Leaching – Excessive reflow time or temperature
