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Description for Dow Dowsil 866 Primerless Silicone Adhesive
One-Part, gray, flowable adhesive with high tensile strength, Heat cure.Brand Dowsil Application Type Bond, Gasketing 1 Part or 2 Part 1-Part Material Form Liquid Substrate Aluminum, Ceramics, Glass, Many reactive metals, Plastics Industry Smart Meters, E-Mobility Solutions, Smart Home Devices Manufacturer Dow Chemistry Silicone Cure Method Heat Cure Temperature (°C) 125, 150 Cure Time (min) 60, 30, Rapid Viscosity (cPs) 48,000, Flowable, Self-leveling Color Gray High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Volume Resistivity (O) 2E+15 (ohm/cm) -
Technical Data for Dow Dowsil 866 Primerless Silicone Adhesive
Overview
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Application Type
- Gasketing
- Adhesive - Bond
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1 Part or 2 Part
- 1-Part
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Material Form
- Liquid
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Industry
- Smart Meters
- Smart Home Devices
- E-Mobility Solutions
- Other - Sealing lids and housings, Attaching baseplates, Connector sealing
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Chemistry
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Application Method
- Dispenser - Applied with simple needle dispensing systems, Automated systems are normally used for high volume process, In low volume, manual dispensing may be appropriate
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Cure Method
- Heat
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Color
- Gray
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Brand
- Dowsil
Specifications
Cure Specs
Cure Temperature (°C) 125, 150 Test Method Cure Time (min) 60, 30, Rapid Test Method Viscosity (cPs) 48,000, Flowable, Self-leveling Work / Pot Time (min) Long Test Method Bond Strength
General Bond Strength (psi) High Shear Strength (psi) 775 Test Method Tear Strength (piw) 25 (ppi) Test Method Tensile Strength (psi) 925, High Material Resistance
Environmental Resistance Environmental resistance High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Moisture/Humidity Resistance Moisture/humidity resistance Conductivity
Dielectric Strength (V/mil) Good, Durable, 500 Volume Resistivity (O) 2E+15 (ohm/cm) Hardness
Shore A Hardness 57 Elongation (%) 210 Flexibility Flexible Other Properties
Specific Gravity 1.290 Test Method Coefficient of Thermal Expansion (CTE) 350 (ppm/°C) Test Method 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., Refer to product label for storage temperature conditions. Containers should be kept tightly closed and kept in cold storage at all times to extend shelf life. The product should be stored in its original packaging with the cover tightly attached to avoid any contamination. Store in accordance with any special instructions listed on the product label. The product should be used by its Use Before date as indicated on the product label. Shelf Life Type from date of manufacture Shelf Life (mon) 12 Not Good For
Don't Use For Some solder flux residues, Organotin compounds, Unsaturated hydrocarbon plasitcizers, Organometallic compounds, Silicone rubber containing organotin catalyst, Sulfur, Polysulfides, Polysulfones, Other sulfur containing materials Don't Use With Non-reactive metal substrates, Nonreactive plastic surfaces, Teflon, Polyethylene, Polypropylene, Rubber substrates that are highly plasticized, Plastic substrates that are highly plasticized -
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Best Practices for Dow Dowsil 866 Primerless Silicone Adhesive
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Surface Preparation
All surfaces should be thoroughly cleaned and/or degreased with Dow 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 the container should be thoroughly mixed prior to use
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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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Curing
Certain materials, chemicals, curing agents and plasticizers can inhibit the cure of addition cure adhesives. Most notable of these include: organotin and other organometallic compounds, silicone rubber containing organotin catalyst, sulfur, polysulfides, polysulfones or other sulfur containing materials, unsaturated hydrocarbon plasitcizers, and some solder flux residues. If a substrate or material is questionable with respect to potentially causing inhibition of cure, it is recommended that a small scale compatibility test be run to ascertain suitability in a given application. The presence of liquid or uncured product at the interface between the questionable substrate and the cured gel indicates incompatibility and inhibition of cure.
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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 on a particular substrate, cohesive failure of the product in a lap shear or similar test is needed to ensure 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.
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Cure Temperature Test Methods
Cure Temperature | Cure Time Test Method |
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125°C | Heat Cure |
150°C | Heat Cure |
Cure Time Test Methods
Cure Time | Test Method |
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60 min | Heat Cure |
30 min | Heat Cure |
Rapid |
Work / Pot Time Test Methods
Work / Pot Time | Temperature |
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Long |
Tear Strength Test Methods
Tear Strength | Test Method |
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25 (ppi) | Die B |
Shear Strength Test Methods
Shear Strength | Type | Substrate | Test Method |
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775 psi | Lap shear strength | Aluminum | Unprimed Adhesion |
Coefficient of Thermal Expansion (CTE) Test Methods
Coefficient of Thermal Expansion (CTE) | CTE Test Method |
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350 (ppm/°C) | by TMA |
Specific Gravity Test Methods
Specific Gravity | Test Method |
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1.290 | Cured |

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