AIM manufactures Lead-Free Soldering Assembly Materials for the Electronics Industry including solder paste, liquid flux, bar solder, wire solder, solder preforms, adhesives, cleaners, chemicals, plating anodes and indium and gold alloys.

Description

WS353 water soluble solder paste has been developed in response to electronics manufacturers demand for an allpurpose,reliably consistent water-soluble solder paste. WS353 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 can be used in fine pitch printing applications and has proven effective in the assembly of 0201 components. WS353 provides consistent printing characteristics and slump resistance during high-speed printing. The excellent activity of WS353 makes it a suitable choice when soldering to standard or difficult-to-wet parts, including lead-free alloys and finishes. In addition, WS353 has proven to substantially reduce voiding under micro-BGAs. The residues of WS353 may be cleaned easily in straight water, with the result being exceptional electrical reliability. In addition, WS353 is designed to not foam during washing, even in high-pressure wash systems.

FEATURES

• EXCELLENT WETTING
• LENGTHY STENCIL LIFE & TACK TIME
• BROAD PRINT PROCESS WINDOW
• ELIMINATES/REDUCES VOIDING UNDER BGAs
• EASILY CLEANED RESIDUES
• LOW FOAMING DURING WASH

STANDARD PASTE COMPOSITION

PRINTER SETUP

Below are some suggested starting parameters for your screen printer. Adjustments will vary between equipment, application and facility environment.

PASTE APPLICATION

• Apply sufficient paste to the stencil to allow a smooth, even roll during the print cycle. A bead diameter of 1/2 to 5/8 inch is normally sufficient to begin.
• Apply small amounts of fresh solder paste to the stencil at frequent, controlled intervals to maintain paste chemistry and workable properties.
• Cleaning of your stencil will vary according to the application. A dry wipe during printing is recommended as needed to yield excellent print results. Never use Isopropyl Alcohol or a blend using Isopropyl Alcohol to wipe the stencil. This practice will negatively affect print life.
• WS 353 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.

RSS Profile Guidelines

• The typical initial rate of rise for the RSS profile is 1.4 to 1.8°C/second.
• Ramp up to 150°C and then soak the assembly for 30 to 60 seconds.
• The soak zone should be controlled between 150 -170°C. Above this point the paste will lose its activator.
• Proceed to spike immediately once the PCB has reached thermal stability.
• Peak temperature is 215ºC ± 5ºC.
• Time above liquidus is 45 ± 15 seconds.
• The total profile length should be between 2 ¾ - 3 ½ minutes from ambient to peak temperature.
• Cool down should be controlled within 4°C/second.

RTS Profile Guidelines

• The typical rate of rise for the RTS profile is 0.7 to 1.5°C/second.
• The profile should be a straight line or concave; it should not be convex.
• 2/3 of the profile should be below 150°C.
• Peak temperature is 215ºC ± 5ºC.
• Time above liquidus is 60 ± 15 seconds.
• The total profile length should be between 3 ½ - 4 minutes from ambient to peak temperature.
• Cool down should be controlled within 4°C/second.

LSP Guidelines

• The typical initial rate of rise for the LSP profile is 1.25°C/second.
• Ramp up to 120°C and then soak the assembly for 120 to 180 seconds.
• Proceed to spike immediately after exiting the soak zone.
• Peak temperature is 215ºC ± 5ºC.
• Time above liquidus is 60 ± 15 seconds.
• The total profile length should be between 4 ½ - 5 minutes from ambient to peak temperature.
• Cool down should be controlled within 4°C/second.