Dow 3-6655 Thermally ConDuctive Encapsulant

Dow 3-6655 Thermally ConDuctive Encapsulant Datasheet
  • Description for Dow 3-6655 Thermally ConDuctive Encapsulant

    Two-part; low viscosity; soft; excellent thermal conductivity.

    Note: This material has been discontinued. Please view the Manufacturer's Recommended Replacement tab or call us at (262) 293-7970 for additional help.

    *See Terms of Use Below

    Application Type Pot, Encapsulate
    1 Part or 2 Part 2 Part
    Material Form Liquid, Silicone elastomer
    Industry Electronic, High voltage transformers, Sensors, Heat sinks
    Manufacturer Dow
    Chemistry Silicone elastomer
    Cure Method 2 Parts
    Cure Temperature (°C) 20 to 25, 100, 125, 150
    Viscosity (cPs) Low, 33,000, Flowable
    Color Gray
    Ozone Resistance Ozone resistance
    Chemical Resistance Good
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55
    Key Specifications UL (Underwriters Laboratory), ULC (Underwriters Laboratories of Canada), NFPA (National Fire Protection Association): UL 94: UL 94 V-0
  • Technical Data for Dow 3-6655 Thermally ConDuctive Encapsulant

    Overview
    • Application Type
    • 1 Part or 2 Part
      • 1 Part or 2 Part - 2 Part
    • Material Form
      • Elastomer - Silicone elastomer
      • Liquid
    • Industry
    • Chemistry
    • Application Method
      • Dispenser - Automated meter-mix
      • Brush - Manual
    • Cure Method
      • 2-Part Cure - 2 Parts
    • Color
      • Gray
    • Key Specifications
      • UL (Underwriters Laboratory), ULC (Underwriters Laboratories of Canada), NFPA (National Fire Protection Association): UL 94: V0 - UL 94 V-0
    Specifications
    Cure Specs
    Cure Temperature (°C) 20 to 25, 100, 125, 150 Test Method
    Viscosity (cPs) Low, 33,000, Flowable
    Work / Pot Time (min) 60 Test Method
    Bond Strength
    Tensile Strength (psi) 45
    Material Resistance
    Ozone Resistance Ozone resistance
    Chemical Resistance Good
    UV Resistance UV resistance
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55
    Conductivity
    Dissipation Factor 0.00100, <0.00010 Test Method
    Dielectric Strength (V/mil) Durable, 13,582,677
    Dielectric Constant 5.20, 5.20 Test Method
    Thermal Conductivity (W/m°K) Excellent, 1.80 Test Method
    Volume Resistivity (O) 1.1E+15
    Hardness
    Elongation (%) 1
    Shore OO Hardness 71
    Flexibility Flexible
    Modulus (psi) 6.5 (Compression at (10%, psi))
    Other Properties
    Specific Gravity 2.700
    Coefficient of Thermal Expansion (CTE) 145 (Linear (micron/m °C or ppm ))
    Flash Point (°F) 392.0
    Business Information
    Shelf Life Details Shelf life is indicated by the “Use By” date found on the product label. For best results, Dow Corning thermally conductive materials should be stored at or below the maximum specified storage temperature. Special precautions must be taken to prevent moisture from contacting these materials. Containers should be kept tightly closed and head or air space minimized. Partially filled containers should be purged with dry air or other gases, such as nitrogen. Any special storage and handling instructions will be printed on the product containers.
    Shelf Life Type From date of manufacture
    Shelf Life (mon) 12
    Not Good For
    Don't Use With non-reactive metal substrates, non-reactive plastic surfaces, Teflon, polyethylene, polypropylene.
  • Best Practices for Dow 3-6655 Thermally ConDuctive Encapsulant

    *See Terms of Use Below

    1. Surface Preparation

      All surfaces should be thoroughly cleaned and/or degreased with solvents such as Dow Corning® brand OS Fluids, naphtha, mineral spirits, or methyl ethyl ketone (MEK). Light surface abrasion is recommended whenever possible, because it promotes good cleaning and increases the surface area for bonding. A final surface wipe with acetone or IPA is also useful to remove residues that may be left behind by other cleaning methods. On some surfaces, different cleaning techniques will give better results than others. Users should determine the best techniques for their applications.

    2. Mixing

      Upon standing, some filler may settle to the bottom of the liquid after several weeks. To ensure a uniform product mix, the material in each container should be thoroughly mixed prior to use. Two-part materials should be mixed in the proper ratio either by weight or volume. The presence of light-colored streaks or marbling indicates inadequate mixing.

    3. Deairing/Degassing

      Automated airless dispense equipment can be used to reduce or avoid the need to de-air. If de-airing is required to reduce voids in the cured elastomer, consider a vacuum de-air schedule of >28 inches Hg (or a residual pressure of 10-20 mm of Hg) for 10 minutes or until bubbling subsides.

    4. Curing

      The one-part moisture-cure adhesives are generally cured at room temperature and in a range of 20 to 80 percent relative humidity. Greater than 90 percent of their full physical properties should be attained within 24 to 72 hours depending on the product chosen. These materials are not typically used for highly confined or deep section cures. Materials will generally cure about 0.25 inch (6.35 mm) per 7 days. Addition-cure adhesives should be cured at 100ºC (212ºF) or above. The cure rate is rapidly accelerated with heat (see heat-cure times in Typical Properties table). Thin sections of less than 2 mils may be cured in 15 minutes at 150ºC (302ºF). For thicker sections, a pre-cure at 70ºC (158ºF) may be necessary to reduce voids in the elastomer. Length of pre-cure will depend on section thickness and confinement of adhesive. It is recommended that 30 minutes at 70ºC (158ºF) be used as a starting point for determining necessary pre-cure time. Addition-curing materials contain all the ingredients needed for cure with no by-products from the cure mechanism. Deep-section or confined cures are possible. Cure progresses evenly throughout the material. These adhesives generally have long working times.

    5. Testing

      Due to the wide variety of substrate types and differences in substrate surface conditions, general statements on adhesion and bond strength are impossible. To ensure maximum bond strength for elastomers and adhesives on a particular substrate, 100 percent cohesive failure of the adhesive in a lap shear or similar adhesive strength is needed. This ensures compatibility of the adhesive with the substrate being considered. Also, this test can be used to determine minimum cure time or to detect the presence of surface contaminants such as mold release agents, oils, greases and oxide films.

  • Manufacturer's Recommended Replacement Materials

    *See Terms of Use Below

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
20 to 25°C
100°C Time to 90 percent of final hardness and adhesion or 90 percent of curve height for elastic modulus additional time may be required for the part to warm to near oven temperature.
125°C Time to 90 percent of final hardness and adhesion or 90 percent of curve height for elastic modulus
150°C additional time may be required for the part to warm to near oven temperature.
Cure Time Test Methods
Cure Time Test Method
Work / Pot Time Test Methods
Work / Pot Time Test Method Temperature
60 min Time to double initial mixed viscosity 25°C
Dielectric Constant Test Methods
Dielectric Constant Test Method
5.20 Dielectric constant, 100 Hz
5.20 Dielectric constant, 100 KHz
Dissipation Factor Test Methods
Dissipation Factor Test Method
0.00100 Dissipation factor, 100 Hz
<0.00010 Dissipation factor, 100 KHz
Thermal Conductivity Test Methods
Thermal Conductivity Temperature
Excellent 25°C
1.80 W/m°K