DOWSIL SE4400
Harmonization Code : 8001.20 | Unwrought tin: Tin alloys
Main features
- Extended 17-Hour Working Window
- Accelerated 30-Minute Heat Cure
- Thermally Conductive PCB Bonding
Product Description
DOWSIL SE 4400 Thermally Conductive Adhesive is a two-part gray silicone adhesive for thermal bonding in PCB system assembly modules. The flowable 1:1 mix has a typical mixed viscosity of 62,500 mPa s and a 17-hour working time at 25 deg C, providing an extended window for mixing, dispensing, and assembly. Heat cure is accelerated to 30 minutes at 150 deg C, and the addition-cure system produces no cure by-products, allowing deep-section and confined curing. The cured material has 0.92 W/(m K) thermal conductivity and 2.72 MPa unprimed lap shear strength on aluminum for combined heat transfer and attachment.
Key features
- Extended working window: A typical 17-hour working time at 25 deg C supports longer dispensing and assembly operations.
- Accelerated heat cure: Typical cure time is 30 minutes at 150 deg C.
- Thermal and bond performance: Cured bulk thermal conductivity is 0.92 W/(m K), with 2.72 MPa unprimed lap shear on aluminum.
Applications / Suitable for
- Thermal bonding in PCB system assembly modules
- Cooling assemblies that require combined attachment and heat transfer
Technical Specifications
General Properties
Color
Gray
The color
Component System
Two
Describes the number of components that must be supplied, mixed, or activated before application or cure.
Specific Gravity
2.15
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.
Mechanical Properties
Elongation
85 %
Elongation is the process of lengthening something.
It is a percentage that measures the initial, unstressed, length compared to the length of the material right before it breaks.
It is commonly referred to as Ultimate Elongation or Tensile Elongation at break.
Electrical Properties
Dielectric Strength
25 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
5.0E+15 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
Thermal Conductivity
0.92 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
Typical values for the mixed adhesive before cure.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Number of parts | Two | Product configuration | |
| Mix ratio | 1:1 | Part A to Part B | |
| Color | Gray | As mixed | |
| Mixed viscosity | 62,500 | mPa s | Typical |
| Working time | 17 | hours | At 25 deg C |
| Heat cure time | 30 | min | At 150 deg C |
Technical properties
After-processing / final-state properties
Typical properties of the heat-cured adhesive.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Durometer hardness | 79 | Shore A | Cured |
| Specific gravity | 2.15 | Cured | |
| Tensile strength | 5.6 | MPa | Cured |
| Elongation | 85 | % | Cured |
| Unprimed lap shear | 2.72 | MPa | Aluminum |
| Dielectric strength | 25 | kV/mm | Cured |
| Thermal conductivity | 0.92 | W/(m K) | Cured bulk material |
