Application Type Bond, Seal, Gaskets 1 Part or 2 Part 1 Part Material Form Liquid, Silicone elastomer Substrate Ceramics, Glass, Reactive metals, Plastics, Resins Industry Circuit boards, Light Emitting Diodes (LEDs), E-Mobility Solutions, Smart Meters, CRT module, Electrical leads, Electronic equipment, Electronics, LCD module, Modules, PDP module, Power supplies, PWBs Manufacturer Dow Chemistry Silicone elastomer Cure Method Moisture, RTV 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 Extrusion Rate 179 (g/min)
Technical Data for Dow 839 Silicone Adhesive/Sealant
1 Part or 2 Part
- 1 Part or 2 Part - 1 Part
- Elastomer - Silicone elastomer
- Silicone - Silicone elastomer
- Dispenser - Automated or manual needle dispensing systems
- RTV (Room Temperature Vulcanization) - RTV
- Translucent - Translucent
Cure Temperature (°C) 20 to 25 Cure Time (min) 2,880 Viscosity (cPs) Non-flow Tack Free Time (min) 35 Test Method
Peel Strength (piw) 25.5 (N/cm2) Shear Strength (psi) 140 Test Method Tensile Strength (psi) 285
Environmental Resistance Environmental resistance High Temperature Resistance (°C) 200 Low Temperature Resistance (°C) -45, -55 Moisture/Humidity Resistance Moisture/humidity resistance
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)
Shore A Hardness 32 Elongation (%) 345 Flexibility Flexible
Extrusion Rate 179 (g/min) Specific Gravity 1.020 Coefficient of Thermal Expansion (CTE) 300 (Linear (micron/m °C or ppm ))
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
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.
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.
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.
Comparable Materials for Dow 839 Silicone Adhesive/Sealant
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Tack Free Time Test Methods
|Tack Free Time||Tack Free Temperature|
Shear Strength Test Methods
|140 psi||Lap shear strength|
Dielectric Constant Test Methods
|Dielectric Constant||Test Method|
|2.51||Dielectric constant, 100 Hz|
|2.49||Dielectric constant, 100 KHz|
Dissipation Factor Test Methods
|Dissipation Factor||Test Method|
|0.00090||Dissipation factor, 100 Hz|
|<0.00020||Dissipation factor, 100 KHz|