The WS150 is no longer available. It has been replaced by the WS159

Product Description
The WS150 water washable solder paste is designed to meet the requirements for reliable solder joints in PCB board assemblies. It displays previously unseen level of repeatability and consistency. WS150 is halide-free, has a neutral pH and extended tack and stencil life. Residues can be cleaned using warm water with reduced foaming characteristics.

Attributes

Enhanced activity for tough to solder boards and components

Excellent slump resistance

High speed stencil printing up to 150mm/sec

Excellent tack performance and printer open time

Extended “between-print” abandon time

Very cleanable post solder residues

Performance
The performance of solder paste depends in part on the metal content, solder alloy and the solder particle size range. Increasing metal content reduces the tendency to slump and reduces the tack life of the paste, while the solder balling performance improves.

Refrigeration and storage It is recommended to store WS150 at 5-10°C. The paste should be removed from cold storage a minimum of 8 hours in the unopened container prior to use. If the paste does not reach room temperature, it may stick to the stencil, not deposit onto the SMT pads, de-wet pads during reflow, outgas during reflow, or produce solder balls. Avoid direct sunlight.

Handling and shelf life
The optimum temperature and humidity are 75°F and 60% or below respectively. Provided WS150 water washable solder paste is stored tightly sealed in the original container at 5-10°C, a minimum shelf life of 6 months can be expected. Air shipment is recommended to minimize the time that containers are exposed to higher temperatures.

Printing
The WS150 water soluble solder paste is currently available for stencil printing down to 16 mil (0.4mm) pitch devices with type 3 powder (-325+500 mesh). Printing at up to 100 mm/sec. can be reliably achieved in production using a metal squeegee blade. This is due to a unique rheology, which ensures that the higher shear rate viscosity is relatively low and the thixotropic index is high enough to ensure excellent definition and slump resistance, while maintaining good roll and drop off behavior. High squeegee pressures are not required, making WS150 particularly useful for second side printing processes.

Reflow
Reflow should be performed with a peak of 20-40°C above the liquid temperature of the alloy (depending on the type of board). This temperature should be maintained for 30-60 seconds. Profiles should have less than a 3-minute preheat time above 260°F(130°C) to insure proper wetting of fine pitch leads.

Cleaning
The post reflow residue of WS150 water soluble solder paste must be removed. It is suggested that the residues are removed as soon after reflow as possible, although effective cleaning can be effected up to 3 days after reflow allowing time for secondary processing. Cleaning can be achieved using moderate temperatures 25-700C in most conventional aqueous cleaners. Cleaning takes typically 2-5 minutes.

Problems may also occur when the same cleaner is used for both solder paste and liquid flux. 150N, VOC551, and WS100A liquid fluxes have proved to be compatible, as has the WS101 cored wire. Health & Safety
This product, during handling or use, may be hazardous to health or the environment. Read the Material Safety Data Sheet and warning label before using this product.

Packaging
The WS150 water washable solder paste is also available in: 500gram or 250 gram plastic jar. 1 Kilogram, 500 gram or 250 gram cartridge for direct application. DEK ProFlow cassettes available upon request.