Indium 5.7LT Solder Paste
Product Data Sheet
Indium5.7LT Solder Paste
• Formulated for use with the eutectic 58Bi/42Sn and 57Bi/42Sn/1Ag alloys
• Low temperature Pb-Free solution
• Clear residue
• Exceptional wetting in an air reflow
Indium5.7LT is an air reflow, halogen-free, no-clean solder paste designed for assembly processes using the eutectic Sn/Bi and Sn/Bi/Ag alloys. This paste is a moderate residue product with exceptional wetting capabilities. The low activation temperature of Indium5.7LT, in combination with the Sn/Bi alloy, can be especially useful as a low temperature, Pb-Free solution.
Indium Corporation manufactures low-oxide spherical powder composed of the 58Bi/42Sn eutectic alloy in the industr y 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 83-92% for standard alloy compositions.
Standard packaging of Indium5.7LT is packaged in 4oz. jars and 6oz. and 12oz. car tridges. For dispensing applications, 10cc and 30cc syringes are standard. Other packaging options may be available upon request.
Storage and Handling Procedures
Refrigerated storage will prolong the shelf life of solder paste. Storage temperatures should not exceed 25°C. The shelf life of Indium5.7LT is 6 months at storage temperatures <5°C. When storing solder paste contained in syringes and cartridges, they 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 var y with container size. Paste temperature should be verified before use. Jars and cartridges should be labeled with date and time of opening.
Indium Corporation’s internationally experienced engineers provide in-depth technical assistance to our customers. Thoroughly knowledgeable in all facets of Material Science as it applies to the electronics and semiconductor sectors, Technical Support Engineers provide expert advice in solder proper ties, alloy compatibility and selection of solder preforms, wire, ribbon and paste. Indium Corporation’s Technical Support engineers provide Rapid Response to all technical inquiries.
Material Safety Data Sheets The MSDS for this product can be found online at http://www.indium.com/techlibrary/msds.php
BELLCORE AND J-STD TESTS & RESULTS
• Flux Type Classification ROL0
• Present of Halide
Fluoride Spot Test Pass Ag Chromate Pass Quantitative Halide Condent 0%
• Post Reflow Flux Residue
(ICA Test) <5% of solder paste
• Corrosion Pass
• SIR (ohms) Pass
• Acid Value ~110
• Typical Solder Paste Viscosity 2000 Poise
(Eutectic Sn/Bi, Type 3)
Malcolm (10PRM, 5min)
• Typical Tackiness 30g
• Solder Ball Test Pass
• Wetting Test Pass
• Slump Test Pass
Electroformed and laser cut/electropolished stencils produce the best printing characteristics among stencil types. Stencil aper ture design is a crucial step in optimizing the print process. The following are a few general recommendations:
• Discrete components — A 10-20% reduction in stencil aperture area may significantly reduce or eliminate 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).
• A minimum aspect ratio of 1.5 is suggested for adequate release of solder paste from stencil apertures. 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: >8 hrs. @ 30-60% R.H. & 22-28°C
Indium5.7LT is designed for no-clean applications, however the flux can be removed if necessary by using a commercially available flux residue remover.
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 055
This profile is designed for use with Indalloy #281 and can ser ve as a general guideline in establishing a reflow profile for use with other alloys. Adjustments to this profile may be necessar y based on specific process requirements.
A linear ramp rate of 0.5°-1°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 unnecessar y depletion of fluxing capacity when using higher temperature alloys.
A peak temperature of 25°-45°C (175°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.
A rapid cool down is desired to form a fine grain structure. Slow cooling will form a large grain structure, which typically exhibits poor fatigue resistance. The acceptable cooling range is 0.5°C-6.0°C/second (2.0°-6.0°C/second is ideal).
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.