DOWSIL 738 ELECTRICAL SEALANT
Harmonization Code : 3214.10.00 | Putty and other mastics | Resin cements, caulking compounds and other mastics
Main features
- One-Part Moisture-Cure Sealing
- Non-Sag Placement Control
- 500% Cured Elongation
Product Description
DOWSIL™ 738 Electrical Sealant is a one-part, white, non-flowing moisture-cure silicone adhesive and sealant for bonding and sealing electrical assemblies. It cures at room temperature without component mixing or oven curing and can be heat-accelerated when faster in-line processing is required. The cured elastomer combines 500% typical elongation with Shore A 35 hardness, providing flexibility and stress relief in electrical components, circuit boards, assemblies and housings.
Key features
- One-part moisture cure: Requires no component mixing and cures at room temperature without an oven.
- Non-flowing consistency: Supports controlled application and placement during bonding and sealing operations.
- Flexible cured elastomer: Provides 500% typical elongation for stress relief in electrical assemblies.
Applications / Suitable for
- Bonding and sealing electrical assemblies
- Circuit boards and assembled electronic systems
- Electrical components and housings
- Battery-pack assembly applications
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Specific Gravity
1.04
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
Viscosity
Non-flowing 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
Mechanical Properties
Elongation
500 %
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.
Physical Properties
Tack-Free Time
89 minutes
Electrical Properties
Dielectric Strength
19 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.
Thermal Properties
Thermal Conductivity
0.2 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.
Mechanical Properties
Peel Strength
16.5 N/cm
Additional Information
Technical properties
As-supplied / before-processing properties
Typical characteristics of the sealant before cure. Typical values are not intended for use as specifications.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Color | White | — | As supplied; typical |
| Flow characteristic | Non-flowing | — | As supplied |
| Specific gravity | 1.04 | — | At 25°C; typical |
| Tack-free time | 89 | minutes | At 50% relative humidity; typical |
| Cure system | Moisture cure | — | One-part, room-temperature cure; optional heat acceleration |
Technical properties
After-processing / final-state properties
Typical properties of the cured silicone elastomer. Typical values are not intended for use as specifications.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Durometer hardness | 35 | Shore A | Cured material; typical |
| Elongation | 500 | % | Cured material; typical |
| Tensile strength | 360 | psi | Cured material; typical |
