79 Water Clean

BOW ELECTRNOIC SOLDER
TECHNICAL BULLETIN
BOW # 79
WATER CLEAN TAC FLUX

Description :

This product is a tac flux designed for use in the attachment of bumped chips to various substrates. Bow 79 is an activated surfactant blend that is water-soluble. This OA flux is formulated with nonionic surfactants, tackifying agents, and amine hydrohalides. The formula is designed for maximum solderability to all typical substrates and ease of cleaning in low standoff applications resulting in high reliability in a variety of processes.

Physical Properties
% Solids	88.0 +/- 1.0
Viscosity @ 25°C	15 – 25 Kcps
Peak Tac Force	1.4 g/mm2
Density	0.95 +/- .05 g/ml
Wetting Ability	Will wet oxidized silver, palladium and copper
Halide Content	1.6 % by weight
Flux Activity3	H1
SIR3	> 1x108 Ohms (after cleaning)
Ionic Contamination4	0.66 µg/inches2 (4 hour delay) 0.81 µg/inches2 (24 hour delay)
1Haake PK100 viscometer, PQ1B sensor @ 13.6 S-1 2IPC TM-650-2.4.44 3IPC J-STD-004 4Analysis performed with Ionograph 500 M SMD ll at 4 and 24 hour delays prior to cleaning.

Application Recommendation:

Stencil Printing
Typical protocols for solder paste apply. Contact printing with the stencil thickness being equivalent to the desired flux deposit should be used. Metal squeegees should be used to minimize scooping. Attack angles of 45° are optimal. Stencil life of 8 hours can be obtained if the ambient conditions are controlled to below 25°C and relative humidity between 40 and 60%.

Dip Application:
Bumps should be dipped to 0.5 mils or slightly less to transfer sufficient volume. Flux depth on the applicator should be set to allow for enough flux to be present to compensate for the maximum variability of bump height on the chip to leave the minimum deposit on the smallest bump. Flux depth should also be maintained to keep flux at a minimum of 1.0 mil from the chip surface to avoid flux creep on the die surface. Applicator life of 8 hours can be achieved if the ambient conditions are maintained below 25°C and relative humidity between 40 and 60%.

Reflow Parameters:
Most conventional reflow equipment can be utilized with or without an inert atmosphere. A standard reflow profile for bulk soldering is adequate with preheats that promote even temperature distribution across the substrate or components.Temperatures at least 20°C above liquidus should be achieved with the time above liquidus being maintained for 30 to 60 seconds.

Storage and Shelf life:
Six months shelf life is guaranteed if material is stored in its original sealed container in a dry environment with temperatures between 5 and 25°C. Storage for periods longer than 2 months should be done at temperatures between 5 and 10°C to insure that minimal separation takes place in the container. Syringes should be stored tip down. To avoid contamination and shelf life issues, used material should not be returned to its original container.