Indium 6.4R Water-Soluble Pb-Free Solder Paste - SAC305, T4 (88.5 Percent), 500g jar
Solder Paste Features & Benefits
Indium Corporation produces a wide range of solder paste products to fit every need and challenge in the PCB Assembly and semiconductor manufacturing market space.
No-clean solder paste is by far the most prevalent solder paste in modern electronic manufacturing, but there is still a purpose and a fit for water-soluble and RMA solder paste as well. Solder paste can be manufactured in hundreds of alloys and with powder size ranging from Type 3 to Type 8. Solder pastes are available for a wide variety of process deposition techniques, including printing, dipping, dispensing, jetting, and pin transfer assembly. Each formula is specifically designed to meet the gamut of manufacturing challenges that plague the electronics manufacturing industry. Whether you are dealing with warpage induced defects, voiding, insufficient solder paste volume, or electrical or mechanical reliability issues, Indium Corporation’s solder pastes – coupled with our world-renowned technical support – allow for the lowest total cost of ownership and fewer end-of-line defects.
Indium 6.4R
Indium6.4R 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.
Indium6.4R exhibits superior wetting to a variety of surface finishes and exhibits the best voiding performance, with fewest voids, reduced size of largest voids, and overall minimized voiding for BGAs, CSPs, and BTCs (QFNs, DPAKs, LGAs, etc.).
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.
Voiding
The following data was collected using QFNs on a test vehicle. More details can be found in the table. Both SAC305 and Sn63 results are provided using a 4mil stencil. Voiding results are highly dependent on many factors, such as the reflow profile, flux chemistry, alloy, PCB surface finish and design, and components, so your results may vary.
QFN Voiding
| Alloy | Profile | Average | Standard Deviation |
| SAC305 | 5 minutes | 19.48 | 3.65 |
| SAC305 | 3 minutes | 22.15 | 2.45 |
| Sn63 | 5 minutes | 29.02 | 1.66 |
| Sn63 | 3 minutes | 23.38 | 3.46 |
Compatible Products
- Rework Flux: TACFlux 025-NP
- Flux Pen: FP-1095-NF
- Cored Wire: CW-301
- Wave Flux: 1095-NF
Storage and Handling Procedures
Refrigerated storage will prolong the shelf life of solder paste. The shelf life of Indium6.4R is 6 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 and before opening the jar. Ideally, the working environment would be 23–28°C and 40–60% RH. Generally, 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 date and time of opening.
Packaging
Standard packaging for stencil printing applications includes wide-mouth 500g jars and 600g cartridges. For dispensing applications, 30cc syringes are available. Other packaging options may be available upon request.
Cleaning
Indium6.4R 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.