Dow Dowsil 340 Heat Sink Compound

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Description for Dow Dowsil 340 Heat Sink Compound

One-Part, White, Moderate thermal conductivity compound. Suitable for thermal coupling of electrical devices and PCB assemblies to heat sinks.

*See Terms of Use Below

Brand	Dowsil
Chemical Resistance	Good, Chemical Resistance: Resistance to minimal or intermittent solvent exposure
Application Type	Grease
1 Part or 2 Part	1-Part
Material Form	Grease
Industry	Diodes, Heat Sink Compound, PCB assemblies, Flyback Transformers, Smart Meters, Aircraft engines, E-Mobility Solutions, Smart Home Devices, Aircraft engines, 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
Ozone Resistance	Ozone resistance
Arc Resistance (sec)	Arc resistance
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
Volume Resistivity (O)	2.2E+15, 2e15 (ohms/cm)
Evaporation (%)	0
Can Be Used In Conjunction With These Materials	Silicone materials

Best Practices for Dow Dowsil 340 Heat Sink Compound

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Technical Data for Dow Dowsil 340 Heat Sink Compound

*See Terms of Use Below

Overview

Chemical Resistance
- Chemical Resistance - Good
- Chemical Resistance : Relative Solvent Resistance - Resistance to minimal or intermittent solvent exposure
Application Type
- Lubricant - Grease
1 Part or 2 Part
- 1-Part
Material Form
- Grease
Industry
- Smart Meters
- Smart Home Devices
- E-Mobility Solutions
- Aircraft - Aircraft engines
- Electronics - Diodes, Electrical devices, High-voltage corona, Silicon-controlled rectifiers, Transistors, TV sets
- Heat sink - Heat Sink Compound
- Printed Circuit Board (PCB) - PCB assemblies
- Transformers - Flyback Transformers
- Engine - Aircraft engines
Chemistry
- Other - Zinc Oxide
- Silicone - Polydimethylsiloxane
Application Method
- Dispenser - Automated or manual dispensing
Cure Method
- None - Non-curing
Color
- White
Can Be Used In Conjunction With These Materials
- Other - Silicone materials
Brand
- Dowsil

Specifications

Cure Specs

Viscosity (cPs)	542,000, Non-flowing, Low bleed

Material Resistance

Ozone Resistance	Ozone resistance
Arc Resistance (sec)	Arc resistance	Test Method
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

Conductivity

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

Other Properties

Specific Gravity	2.100	Test Method
Evaporation (%)	0
Flash Point (°F)	213.8

Business Information

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

*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.
Comparable Materials for Dow Dowsil 340 Heat Sink Compound

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Spec Engine^® Results
- Dowsil SE 4490 CV Thermally Conductive Compound(Dow)
  • One part • Non-flowing • Good thermal conductivity • Controlled silicone volatility • White • Heat flow away from PCB system components can increase reliability
- TC-5021 Thermally Conductive Compound(Dow)
  Non-curing, thermally conductive silicone paste; low thermal resistance; high thermal conductivity.
- CircuitWorks Silver Conductive Grease(Chemtronics (ITW))
  • High electrical conductivity • Excellent thermal conductivity • Provides protection against wear • Protects against moisture and corrosion • Very low viscosity vs. temperature change • Lubrication of Substation Switches orCircuit Breakers • Heat Dissipation from Transformers • Low or Medium Speed SlidingContacts • Static Grounding on Seals or O-Rings • Extending the Life of RotatingSwitches
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