DOWSIL 744 RTV SILICONE SEALANT
Harmonization Code : 3506.91.90.99 | Prepared glues and other prepared adhesives, not elsewhere specified or included; products suitable for use as glues or adhesives, put up for retail sale as glues or adhesives, not exceeding a net weight of 1 kg ; Adhesives based on polymers of headings 3901 to 3913 or on rubber; Other ; Other
Main features
- One-Part Moisture-Cure Sealing
- 70 psi Cured Tensile Strength
- Primerless Aluminum Bonding
Product Description
DOWSIL™ 744 RTV Adhesive Sealant is a one-part, white, non-flowing moisture-cure silicone adhesive for bonding large components such as batteries and capacitors to circuit boards. It cures at room temperature without component mixing or mandatory oven processing, while optional heat acceleration can support faster in-line processing. After cure, the silicone elastomer combines 590% typical elongation with Shore A 37 hardness, providing flexibility and stress relief within bonded assemblies.
Key features
- One-part moisture cure: Requires no component mixing and cures at room temperature under ambient humidity.
- Non-flowing consistency: Supports controlled placement during manual or automated dispensing.
- Flexible cured elastomer: Provides 590% typical elongation and a tensile modulus of 70 psi for stress-relieving bonds.
Applications / Suitable for
- Bonding batteries to circuit boards
- Bonding capacitors to circuit boards
- Automated or manual dispensing processes
Technical Specifications
General Properties
Specific Gravity
1.42
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
Skin Time
10 minutes
Viscosity
753,000 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
Mechanical Properties
Elongation
590 %
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
55 minutes
Electrical Properties
Dielectric Strength
15 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
5E + 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
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.
UL 94 Rating
94-HB
Flammability rating classification.
It determines how fast a material burns or extinguishes once it is ignited.
HB: slow burning on a horizontal specimen; burning rate less than 76 mm/min for thickness less than 3 mm or burning stops before 100 mm
V-2: burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.
V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
5VB: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.
5VA: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole
Additional Information
Technical properties
As-supplied / before-processing properties
Typical characteristics of the adhesive 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 |
| Tack-free time | 55 | minutes | At 25°C; typical |
| Cure system | Moisture cure | — | One-part; normally cured at room temperature and 30–80% relative humidity |
| Shelf life | 12 | months | When stored at 25°C; typical |
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 |
|---|---|---|---|
| Specific gravity | 1.42 | — | Cured material; typical |
| Durometer hardness | 37 | Shore A | Cured material; typical |
| Tensile strength | 395 | psi | 2.7 MPa; 28 kg/cm²; cured material; typical |
| Elongation | 590 | % | Cured material; typical |
| Tensile modulus | 70 | psi | 0.5 MPa; 5 kg/cm²; cured material; typical |
| Tear strength | 30 | ppi | Die B; 20 N/cm; cured material; typical |
| Unprimed lap-shear adhesion | 430 | psi | Aluminum substrate; 3 MPa; 29 kg/cm²; typical |
