DOWSIL 3-1818
Harmonization Code : 5906100000 | Adhesive tape of a width not exceeding 20cm
Main features
- Glass-Bead Bondline Control
- 1.68 W/(m K) Thermal Conductivity
- 10-Minute Cure at 150 deg C
Product Description
DOWSIL 3-1818 Thermally Conductive Adhesive is a one-part, gray, flowable silicone adhesive for thermally conductive bonding in electronic assemblies. The material contains glass beads for bondline control and has a typical viscosity of 758,000 cP with a thixotropy value of 3.4. Cure schedules include 60 minutes at 100 deg C, 45 minutes at 125 deg C, and 10 minutes at 150 deg C. Typical cured thermal conductivity is 1.68 W/(m K), with typical unprimed aluminum adhesion of 560 psi.
Key features
- Glass-bead bondline control: The adhesive contains glass beads for controlled bondline thickness.
- Cured thermal conductivity: Typical cured thermal conductivity is 1.68 W/(m K).
- Elevated-temperature cure: The shortest listed cure schedule is 10 minutes at 150 deg C.
Applications
Thermally conductive bonding in electronic assemblies where controlled bondline thickness and heat transfer are required.
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Color
Gray
The color
Specific Gravity
2.63
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume.
For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.
Physical Properties
Thixotropic index
3.4
Thixotropic Index is a ratio of a material s viscosity at two different speeds in Ambient temperature, generally different by a factor of ten.
A thixotropic material s viscosity will decrease as agitation or pressure is increased. It indicates the capability of a material to hold its shape. Mayonnaise is a great example of this. It holds its shape very well, but when a shear stress is applied, the material easily spreads.
It helps in choosing a material in accordance to the application, dispense method and viscosity of a material.
Viscosity
76,000 mPa.s
Viscosity is a measurement of a fluid’s resistance to flow.
Viscosity is commonly measured in centiPoise (cP). One cP is defined as
the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP.
A product like honey would have a much higher viscosity -around 10,000 cPs-
compared to water. As a result, honey would flow much slower out of a tipped glass than
water would.
The viscosity of a material can be decreased with an increase in temperature in
order to better suit an application
Electrical Properties
Dielectric Strength
16 kV/mm
Dielectric strength is measured in kV per mm and is calculated by the Breakdown voltage divided by the thickness of the tested material.
Those two properties go hand in hand and while Breakdown voltage is always thickness dependent, dielectric strength is a general material property.
As an example, the dielectric strength of Polyimide is 236 kV/mm. If we place 1mm of Polyimide between two electrodes, it will act as an insulator until the voltage between the electrodes reaches 236 kV. At this point it will start acting as a good conductor, causing sparks, potential punctures and current flow.
Volume Resistivity
6.85 E+13 Ohms⋅cm
Volume resistivity, also called volume resistance, bulk resistance or bulk resistivity is a thickness dependent measurement of the resistivity of a material perpendicular to the plane of the surface.
Thermal Properties
Temperature Range
-45°C to 200 °C
Thermal Conductivity
1.7 W/m.K
Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance.
Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system.
Additional Information
Technical properties
As-supplied / before-processing properties
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Color | Gray | - | As supplied |
| Number of parts | 1 | part | As supplied |
| Flow behavior | Flowable | - | As supplied |
| Viscosity | 758,000 | cP | As supplied |
| Thixotropy | 3.4 | - | As supplied |
| Bondline control | Glass beads | - | As supplied |
| Heat-cure schedule | 60; 45; 10 | minutes | At 100; 125; 150 deg C, respectively |
