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Description for Dow 839 Silicone Adhesive/Sealant
Silicone adhesive sealant one-part, translucent blue, moisture cure adhesives are generally cured at room temperature, non-flowing, automated or manual needle dispensing systems.Application Type Bond, Seal, Gaskets 1 Part or 2 Part 1-Part Material Form Pre-Cure: Paste, Post-Cure: Elastomer Substrate Ceramics, Glass, Reactive metals, Plastics, Resins Industry Circuit boards, Light Emitting Diodes (LEDs), Smart Meters, E-Mobility Solutions, Smart Home Devices, CRT module, Electrical leads, Electronic equipment, Electronics, LCD module, Modules, PDP module, Power supplies, PWBs Manufacturer Dow Chemistry Silicone elastomer Cure Method RTV, Moisture Cure Temperature (°C) 20 to 25 Cure Time (min) 2,880 Viscosity (cPs) Non-flow Color Blue, Translucent High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Volume Resistivity (O) 2.5E+14 (ohms/cm) Extrusion Rate (g/sec) 10,740 -
Technical Data for Dow 839 Silicone Adhesive/Sealant
Overview
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1 Part or 2 Part
- 1-Part
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Material Form
- Elastomer - Post-Cure: Elastomer
- Paste - Pre-Cure: Paste
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Industry
- LED (Light-Emitting Diodes) - Light Emitting Diodes (LEDs)
- Smart Meters
- Smart Home Devices
- E-Mobility Solutions
- Electronics - Circuit boards, CRT module, Electrical leads, Electronic equipment, LCD module, Modules, PDP module, Power supplies, PWBs
- Power Supplies
- Industrial - Housings, Yoke
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Chemistry
- Silicone - Silicone elastomer
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Application Method
- Dispenser - Automated or manual needle dispensing systems
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Cure Method
- Moisture / Condensation Cure - Moisture
- RTV (Room Temperature Vulcanization) - RTV
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Color
- Translucent - Translucent
- Blue
Specifications
Cure Specs
Cure Temperature (°C) 20 to 25 Cure Time (min) 2,880 Viscosity (cPs) Non-flow Tack Free Time (min) 35 Test Method Bond Strength
Peel Strength (piw) 25.5 (N/cm2) Shear Strength (psi) 140 Test Method Tensile Strength (psi) 285 Material Resistance
Environmental Resistance Environmental resistance High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Moisture/Humidity Resistance Moisture/humidity resistance Conductivity
Dissipation Factor 0.00090, <0.00020 Test Method Dielectric Strength (V/mil) Good, 480 Durable, 19 (kV/mm) Dielectric Constant 2.51, 2.49 Test Method Volume Resistivity (O) 2.5E+14 (ohms/cm) Hardness
Shore A Hardness 32 Elongation (%) 345 Flexibility Flexible Other Properties
Extrusion Rate (g/sec) 10,740 Specific Gravity 1.020 Coefficient of Thermal Expansion (CTE) 300 (Linear (micron/m °C or ppm )) Business Information
Shelf Life Details Shelf life is indicated by the “Use Before” date found on the product label. For best results, Dow Corning RTV adhesives should be stored at or below 25°C (77°F). Special precautions must be taken to prevent moisture from contacting these materials. Containers should be kept tightly closed with head or air space minimized. Partially filled containers should be purged with dry air or other gases, such as nitrogen. Shelf Life Temperature (°F) <90 Shelf Life Type from date of manufacture Shelf Life (mon) 24 Not Good For
Don't Use With Plastic, rubber -
Best Practices for Dow 839 Silicone Adhesive/Sealant
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Surface Preparation
All surfaces should be thoroughly cleaned and/or degreased with Dow Corning® brand OS Fluids, naphtha, mineral spirits, methyl ethyl ketone (MEK) or other suitable solvent. Solvents such as acetone or isopropyl alcohol (IPA) do not tend to remove oils well, and any oils remaining on the surface may interfere with adhesion. 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. Some cleaning techniques may provide better results than others
users should determine the best techniques for their particular applications.
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Mixing
Upon standing, some filler may settle to the bottom of the liquid containers 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 (1:1 or 10:1) either by weight or volume. The presence of light colored streaks or marbling indicates inadequate mixing.
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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 for 10 minutes or until bubbling subsides.
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Tack Free Time Test Methods
Tack Free Time | Tack Free Temperature |
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35 min | 25°C |
Shear Strength Test Methods
Shear Strength | Type |
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140 psi | Lap shear strength |
Dielectric Constant Test Methods
Dielectric Constant | Test Method |
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2.51 | Dielectric constant, 100 Hz |
2.49 | Dielectric constant, 100 KHz |
Dissipation Factor Test Methods
Dissipation Factor | Test Method |
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0.00090 | Dissipation factor, 100 Hz |
<0.00020 | Dissipation factor, 100 KHz |