Indium 6.3 Water-Soluble Paste - Sn63/Pb37, T3 (89.5 percent); 600g Cartridge
Tin-Lead (SnPb) Solder Paste
Indium Corporation offers a number of SnPb solder pastes for circuit board assembly and high-Pb applications common in semiconductor packaging.
With decades of proven flux technology, these solder pastes will provide you with the highest end-of-line yields.
Storage and Handling Procedures
Refrigerated storage will prolong the shelf life of solder paste. The shelf life of Indium6.3 is 4 months when stored at <10°C. When storing solder paste contained in syringes and cartridges, the packages should be stored with tip down.
Solder paste should be allowed to reach ambient working temperature prior to use. Generally, paste should be removed from refrigeration at least 2 hours before 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 date and time of opening.
Placement
The high tack value of Indium6.3 assures consistent component holding power. It allows high-speed component placement operation, including use of tall components. Tack remains adequate for over 24 hours over a wide humidity range.
Printing
Stencil Design:
Electroformed and laser cut/electropolished 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.
Wetting
Indium6.3 exhibits excellent wetting on a wide variety of surface finishes, such as immersion tin, immersion silver, nickel/gold, palladium, alloy 42, HASL, and OSP, under both air and nitrogen reflow atmosphere. The solder joints yielded are very shiny and smooth, including those of ultrafine-pitch components. Indium6.3 has ultra-low voiding performance. Minimal voiding can be achieved with optimal process conditions.
Cleaning
Residue Cleaning: Indium6.3 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 60psi and a temperature of at least 55°C. These parameters are a function of board complexity and cleaner efficiency.
Stencil Cleaning: This 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.