• Alloy: Sn63/Pb37
• Type 4 powder (89.5 percent metal load)
• Quantity: 700g cartridge
• Compatibility with common conformal coatings
• Clear, benign residue 

NC-SMQ 92H is a halogen-free, air-reflow, no-clean solder paste formulated for low flux spatter. It provides consistent fine-pitch paste deposition, and excellent stencil life and tack time. NC-SMQ®92H has a hard flux residue and can accommodate reflow temperatures higher than typically required for many Pb-containing alloys. NC-SMQ 92H meets or surpasses all ANSI/J-STD-004, -005 specifications and Bellcore test criteria.

Alloys

Indium Corporation manufactures low-oxide spherical powder composed of SnPb and SnPbAg in the industry standard Type 3 mesh size. Other, non-standard, mesh sizes are available upon request. The weight ratio of the flux/vehicle to the solder powder is referred to as the metal load and is typically in the range of 84–92% for standard alloy compositions.

Storage and Handling Procedures

Refrigerated storage will prolong the shelf life of solder paste. Solder paste packaged in cartridges should be stored tip down.

Solder paste should be allowed to reach ambient working temperature prior to use. Generally, the paste should be removed from refrigeration at least two hours before use. The 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.

Compatible Products 

• Rework Flux: PoP Flux 8.9HF-LV, TACFlux 018
• Cored Wire: CW-807
• Wave Flux: WF-9945, WF-9955, FP-500, NC-771

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 the adequate release of solder paste from stencil apertures, a minimum aspect ratio of 1.5 is suggested. The aspect ratio is defined as the width of the aperture divided by the thickness of the stencil.

Cleaning

NC-SMQ®92H is designed for no-clean applications. However, the flux can be removed if necessary by using a commercially available flux residue remover.

Stencil cleaning is best performed using isopropyl alcohol (IPA) as a solvent. Most commercially available non-water-based stencil cleaners work well.