• Compatibility with common conformal coatings
• Clear, benign residue
• Superior stencil life
• Exceptional wetting in air reflow
• Outstanding print characteristics
Indium Corporation manufactures low-oxide spherical powder composed of Sn-Pb and Sn-Pb-Ag 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 85-92% for standard alloy compositions.
Standard Product Specifications
Standard packaging for stencil printing applications includes 4 oz. jars and 6 oz. or 12 oz. cartridges. Packaging for enclosed print head systems is also readily available. For dispensing applications, 10cc and 30cc syringes are standard. Other packaging options are available on request.
Storage and Handling Procedures
Refrigerated storage will prolong the shelf life of solder paste. The shelf life of NC-SMQ92H is 6 months when stored at <10°C. Solder ® paste packaged in syringes and cartridges should be stored tip down.
Solder paste should be allowed to reach ambient working temperature prior to use. Generally, paste should be removed from refrigeration at least two 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.
Material Safety Data
The MSDS for this product can be found online at
BELLCORE AND J-STD TESTS & RESULTS
• Flux Type Classification - ROL0
• Flux Induced Corrosion (Copper Mirror) - Pass
• Presence of Halide Fluoride Spot Test - Pass
Elemental Analysis (Br, Cl, F) - 0%
• Post Reflow Flux Residue (ICA Test) - 46%
• Corrosion - Pass
• SIR - Pass
• Acid Value - 128
• Typical Solder Paste Viscosity (Sn63, 90%, Type 3) Malcom (10 rpm) - 1400 poise
• Typical Thixotropic Index; SSF (ICA Test) - -0.75
• Slump Test - Pass
• Solder Ball Test - Pass
• Typical Tackiness - 32 grams
• Wetting Test - Pass
• SIR - Pass
• Electromigration - Pass
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 20 mil 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 adequate release of solder paste from stencil aperatures, 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.
The following are general recommendations for stencil printer optimization. Adjustments may be necessary based on specific process requirements:
• Solder Paste Bead Size: 20-25mm diameter
• Print Speed: 25-100mm/sec.
• Squeegee Pressure: 0.018-0.027kg/mm of blade length
• Underside Stencil Wipe: Once ever y 10-25 prints
• Solder Paste Stencil Life: >12 hrs. 30-60% R.H. & 22-28°C
NC-SMQ92H is designed for no-clean applications. However, the flux can be removed if necessary by using a commercially available flux residue remover.
Stencil Cleaning: This is best-per formed using an automated stencil cleaning system for both stencil and misprint cleaning to prevent extraneous solder balls. Most commercially available stencil cleaning formulations including isopropyl alcohol (IPA) work well.
• Rework Flux: TACFlux 018
This profile is designed for use with Sn63/Pb37 and Sn62/Pb36/Ag2 and can serve as a general guide- line in establishing a reflow profile for use with other alloys. Adjustments to this profile may be necessary based on specific process requirements.
A linear ramp rate of 0.5°-2.0°C/second allows gradual evaporation of volatile flux constituents and prevents defects such as solder balling/ beading and bridging as a result of hot slump.
It also prevents unnecessary depletion of fluxing capacity when using higher temperature alloys. A profile with an extended soak above 150°C can be implemented to reduce void formation and minimize tombstoning when required.
A peak temperature of 25°-45°C (215°C shown) above the melting point of the solder alloy is needed to form a quality solder joint and achieve acceptable wetting due to the formation of an intermetallic layer. If the peak temperature is excessive, or the time above liquidus greater than the recommended 30-90 seconds, flux charring, excessive intermetallic formation and damage to the board and components can occur.
A rapid cool down of <4°C/second is desired to form a fine grain structure. Slow cooling will form a large grain structure, which typically exhibit poor fatigue resistance. If excessive cooling >4°C/ second is used, both the components and the solder joint can be stressed due to a high CTE mismatch.
This product data sheet is provided for general information only. It is not intended, and shall not be construed, to warrant or guarantee the performance of the products described which are sold subject exclusively to written warranties and limitations thereon included in product packaging and invoices.