• Alloy: Sn63/Pb37
• Type 4 powder (89.5 percent metal load)
• Quantity: 500g jar
• Superior wetting to a variety of surface finishes and exhibits the best voiding performance
• Low-voiding water-soluble flux for solder paste: Reduced largest voids, fewer voids, minimized voiding overall, For BGA, CSP, and bottom termination components, such as QFNs and DPAKs

Indium6.6HF

Indium6.6HF is a versatile, water-soluble solder paste flux, formulated for air or nitrogen reflow. It is capable of SnPb and Pb-free assembly processes with an exceptional reflow process window. This solder paste provides exceptional stencil printing performance, with long stencil life and excellent response-to-pause.

Indium6.6HF exhibits superior wetting to a variety of surface finishes and exhibits the best voiding performance, with the fewest voids, reduced size of largest voids, and overall minimized voiding for BGAs, CSPs, and BTCs (QFNs, DPAKs, LGAs, etc.).

Refrigerated storage will prolong the shelf life of solder paste. The preliminary shelf life of Indium6.6HF is 6 months when stored at <10°C. When storing solder paste contained in syringes and cartridges, the packages should be stored with the tip down.

Solder paste should be allowed to reach ambient working temperature prior to use and before opening the jar. Ideally, the working environment would be 23–28°C and 40–60% RH. Generally, the paste should be removed from refrigeration at least 2 hours prior to use. Actual time to reach thermal equilibrium will vary with container size. Paste temperature should be verified before use. Jars and cartridges should be labeled with the date and time of opening.

Standard packaging for stencil printing applications includes 500g jars and 600g cartridges. For dispensing applications, 30cc syringes are available. Other packaging options may be available upon request.

Stencil Design

Electroformed and laser-cut stencils produce the best printing characteristics among stencil types. Stencil aperture design is a crucial step in optimizing the print process. The following are a few general recommendations:

• Discrete components - A 10–20% reduction of stencil aperture has significantly reduced or eliminated the occurrence of mid-chip solder beads. The “home plate” design is a common method for achieving this reduction.
• Fine-pitch components - A surface area reduction is recommended for apertures of 20mil pitch and finer. This reduction will help minimize solder balling and bridging that can lead to electrical shorts. The amount of reduction necessary is process-dependent (5–15% is common).
• For optimum transfer efficiency and release of the solder paste from the stencil apertures, industry-standard aperture, and aspect ratios should be adhered to.

• Rework Flux: TACFlux 66HF
• Cored Wire: CW-305
• Wave Flux: 1095-NF, WF-1082

The high tack value of Indium6.6HF assures consistent component holding power. It allows high-speed component placement operation, including the use of tall components. Tack remains adequate for over 8 hours over a wide humidity range.

Indium6.6HF flux residue is cleanable up to at least 72 hours after reflow and is best cleaned using DI water with a spray pressure of at least 40psi and a temperature of at least 40°C. These parameters are a function of board complexity and cleaner efficiency. Electrical testing should be performed after the flux residue is removed.

Stencil cleaning is best performed using an automated stencil cleaning system for both stencil and misprint cleaning to prevent extraneous solder particles. Most commercially available stencil cleaners and isopropyl alcohol (IPA) work well.