Kester WP616 is a halogen-free, lead-free, water-soluble solder paste formulation suitable for nitrogen and air reflow applications.

Kester WP616 is a zero-halogen, lead-free, water-soluble solder paste formula for both nitrogen and air reflow applications. WP616 is a breakthrough in water-soluble solder paste technology, providing a  combination of consistent print performance at wide humidity levels, excellent solderability and ease of cleaning, while maintaining a zero-halogen flux formulation. WP616 is a stable water-soluble  formula, providing consistent stencil life, tack time and print definition. WP616 is classified as ORM0 flux under IPC J-STD-004B.

Performance Characteristics:

■ Zero-halogen (none intentionally added)                      

■ Cleaning can be accomplished with heated de-ionized water

■ Consistent printing performance at wide humidity levels (30-60% RH)

■ Good solderability in air under straight profiles

RoHS Compliance

Initial Tackiness (typical): 35 grams Tested to J-STD-005A, IPC-TM-650, Method 2.4.44

Slump Test: Pass Tested to J-STD-005A, IPC-TM-650, Method 2.4.35

Solder Ball Test: Pass Tested to J-STD-005, IPC-TM-650, Method 2.4.43

Viscosity: 2200 poise Malcom Viscometer PCU-203 @ 10 rpm, 25°C,measurement after 9 minutes

Reliability Properties

Copper Mirror Corrosion: Moderate Tested to J-STD-004B, IPC-TM-650, Method 3.1.1.1

Corrosion Test: Moderate Tested to J-STD-004B, IPC-TM-650, Method 3.4.1.2

Surface Insulation Resistivity (SIR):Pass, All Readings >1.0x108 ? Tested to J-STD-004B, IPC-TM-650, Method 2.6.3.7

Surface Insulation Resistivity (SIR):Pass All Readings >1.0x108 ? Tested to J-STD-004A, IPC-TM-650, Method 2.6.3.3

Halogen Content: None Detected Tested to J-STD-004B, IPC-TM-650, Method 2.3.28.1

Electro Chemical Migration (ECM):Pass Tested to J-STD-004B, IPC-TM-650, Method 2.6.14.1

Availability

WP616 is available in the SAC305 alloy with Type 4/5 powder. This is recommended for standard and fine pitch applications. For specific packaging information refer to Kester’s Solder Paste Packaging Chart for available sizes. The appropriate combination depends on process variables and the specific application.

Printing Parameters

Squeegee Blade              80 mm/sec (3 in/sec), process window is under evaluation

Squeegee Speed              25mm/sec–150mm/sec

Stencil Material            Stainless Steel

Temperature/Humidity        Optimal ranges are 20-25°C (68-77°F) and 30-60% RH

Recommended Reflow Profile

The general recommended reflow profile for WP616 formula made with SAC alloys is shown here as a starting point. Your final profile will depend on your board mass and component combination. WP616 has excellent solderability and wetting capabilities in air or nitrogen reflow atmospheres. Please contact Kester Technical Support if you need profiling advice.

Cleaning

WP616 residues are best removed using automated cleaning equipment (in-line) within 48 hours of soldering. Deionized water is recommended for the final rinse. Water temperatures should be 49-60°C (120-140°F). Kester’s 5768 Cleaner can also be used in a 1-2% ratio for aqueous cleaning systems.

Storage, Handling and Shelf Life

Refrigeration is the recommended optimum storage condition for solder paste to maintain consistent viscosity, reflow characteristics and overall performance. WP616 should be stabilized at room temperature prior to printing. WP616 should be kept at standard refrigeration conditions, 0-10°C (32-50°F). Shelf life is 6 months from the date of manufacture when handled properly when held at 0-10°C (32-50°F). Storage of cartridges should be with the small tip down or on their sides, never with the large end down. Jars can be stored with the bottom down and stacked. Never freeze solder paste, this will shorten its shelf life. Please contact Kester Technical Support if you require additional advice regarding storage and handling of this material.

Health and Safety

This product, during handling or use, may be hazardous to your health or the environment. Read the Safety Data Sheet and warning label before using this product.