Brand Dowsil Application Type Grease 1 Part or 2 Part 1 Part Material Form Grease Industry Diodes, Flyback Transformers, Aircraft engines, PCB assemblies, Heat Sink Compound, Aircraft engines, E-Mobility Solutions, Smart Meters, Smart Home Devices, Electrical devices, High-voltage corona, Silicon-controlled rectifiers, Transistors, TV sets Manufacturer Dow Chemistry Zinc Oxide, Polydimethylsiloxane Viscosity (cPs) 542,000, Non-flowing, Low bleed Color White Arc Resistance (sec) Arc resistance Ozone Resistance Ozone resistance Chemical Resistance Good Relative Solvent Resistance Chemical Resistance: Resistance to minimal or intermittent solvent exposure High Temperature Resistance (°C) 177, 200, Thermal Resistance, High-temperature stability, 0.16 (°C*cm2/W) Low Temperature Resistance (°C) -45, -55, Low thermal resistance Evaporation (%) 0 Can Be Used In Conjunction With These Materials Silicone materials
Technical Data for Dow Dowsil 340 Heat Sink Compound
- Lubricant - Grease
1 Part or 2 Part
- 1 Part or 2 Part - 1 Part
- E-Mobility Solutions
- Aircraft - Aircraft engines
- Electronics - Diodes, Electrical devices, High-voltage corona, Silicon-controlled rectifiers, Transistors, TV sets
- Transformers - Flyback Transformers
- Printed Circuit Board (PCB) - PCB assemblies
- Heat sink - Heat Sink Compound
- Smart Meters
- Smart Home Devices
- Engine - Aircraft engines
- Other - Zinc Oxide
- Silicone - Polydimethylsiloxane
- Dispenser - Automated or manual dispensing
- None - Non-curing
Can Be Used In Conjunction With These Materials
- Other - Silicone materials
Viscosity (cPs) 542,000, Non-flowing, Low bleed
Arc Resistance (sec) Arc resistance Ozone Resistance Ozone resistance Chemical Resistance Good Relative Solvent Resistance Chemical Resistance: Resistance to minimal or intermittent solvent exposure UV Resistance UV resistance High Temperature Resistance (°C) 177, 200, Thermal Resistance, High-temperature stability, 0.16 (°C*cm2/W) Test Method Low Temperature Resistance (°C) -45, -55, Low thermal resistance
Dissipation Factor 0.00100, 0.02000 Test Method Dielectric Strength (V/mil) 210 Test Method Dielectric Constant 5.00, 5.00 Test Method Thermal Conductivity (W/m°K) High, 0.67, Moderate thermal conductivity Volume Resistivity (O) 2.2E+15, 2e15 (ohms/cm) Test Method
Specific Gravity 2.100 Test Method Evaporation (%) 0 Flash Point (°F) 213.8
Shelf Life Details 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 the indicated Exp. Date found on the label. Shelf Life Temperature (°F) 100 Shelf Life (mon) 60
Not Good For
Don't Use With Non-reactive metal substrates, Non-reactive plastic surfaces, Teflon, Polyethylene, Polypropylene
Best Practices for Dow Dowsil 340 Heat Sink Compound
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.
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.
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.
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.
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.
Comparable Materials for Dow Dowsil 340 Heat Sink Compound
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High Temperature Resistance Test Methods
|High Temperature Resistance||Test Method|
|0.16 (°C*cm2/W)||Thermal Resistance at 40 psi|
Dielectric Constant Test Methods
|Dielectric Constant||Test Method|
|5.00||100 Hz, ASTM D 150|
|5.00||100 KHz, ASTM D 150|
Dielectric Strength Test Methods
|Dielectric Strength||Test Method|
|210 V/mil||ASTM D 149, Measured using a sample thickness of 50 mils.|
Dissipation Factor Test Methods
|Dissipation Factor||Test Method|
|0.00100||100 Hz, ASTM D 150|
|0.02000||100 KHz, ASTM D 150|
Volume Resistivity Test Methods
|Volume Resistivity||Test Method|
|2e15 (ohms/cm)||ASTM D 1169|
Specific Gravity Test Methods
|Specific Gravity||Test Method|