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DOWSIL™ TC-5515 LT Low Density Thermal Conductive Gap Filler
- Low Density, Soft, & Compliant cured material
- Room-temperature cure in 360 minutes at 25°C
- Tacky surface after cure
Product Description
DOWSIL™ TC-5515 LT Low Density Thermally Conductive Gap Filler is a two-part, room-temperature-curing silicone gap filler designed for lightweight thermal management in EV modules, printed circuit boards, control units, and other heat-generating electronic assemblies. With 2.0 W/m·K thermal conductivity, low cured specific gravity of 1.95, and UL 94 V-0 recognition, TC-5515 LT helps transfer heat from electronic devices to aluminum housings or heat sinks while reducing added module weight. Once cured, the material forms a soft, compliant, and tacky interface that provides stress relief in vibration applications, holds vertical position, supports rework after assembly, and maintains reliable performance across a working temperature range of -40°C to 150°C.
Key Features
2.0 W/m·K thermal conductivity for reliable heat dissipation.
Low density with cured specific gravity of 1.95.
Two-part 1:1 mix ratio by weight or volume.
Room-temperature cure in 360 minutes at 25°C.
Heat-accelerated cure in 30 minutes at 80°C.
Soft, compliant cured material for vibration stress relief.
Non-flowable behavior on flat and vertical surfaces.
Tacky surface after cure for easier rework after assembly.
UL 94 V-0 recognition for flame-rated electronics applications.
Excellent dielectric strength of 19 kV/mm.
High volume resistivity of ≥1.0 × 10¹³ Ω·cm.
Working temperature range of -40°C to 150°C.
Suitable for EV modules, PCB assemblies, control units, battery modules, aluminum housings, and heat sink interfaces.
Technical Specifications
| General Properties | |||||||
| Color Color The color | Part A: White | Part B: Blue | ||||||
| Component System Component System Describes the number of components that must be supplied, mixed, or activated before application or cure. | Two Part | ||||||
| Mix Ratio Mix Ratio The amount of a constituent divided by the total amount of all other constituents in a mixture | 1:1 | ||||||
| Specific Gravity Specific Gravity 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. | A/B: 1.95 | ||||||
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| Physical Properties | |||||||
| Thixotropic index Thixotropic index 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. | 3.5 | ||||||
| Viscosity (Part A) | @10/s 150000 mPa.s | ||||||
| Viscosity (Part B) | @10/s 120000 mPa.s | ||||||
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| Curing Conditions | |||||||
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| Mechanical Properties | |||||||
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| Thermal Properties | |||||||
| Specific Heat Capacity Specific Heat Capacity Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property. It is also an example of an extensive property since its value is proportional to the size of the system being examined. | @20°C 1.40 J/(g⋅°C) | ||||||
| Thermal Conductivity Thermal Conductivity 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. | 2.0 W/m.K | ||||||
| UL 94 Rating UL 94 Rating 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 | V0 | ||||||
| Electrical Properties | |||||||
| Dielectric Strength Dielectric Strength 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. | 19.0 kV/mm | ||||||
| Volume Resistivity Volume Resistivity 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. | ≥ 1.0 E+13 Ohms⋅cm | ||||||
Additional Information
DOWSIL™ TC-5515 LT: Low Density Thermally Conductive Gap Filler for EV Modules
DOWSIL™ TC-5515 LT Low Density Thermally Conductive Gap Filler is a two-part, room-temperature-curing silicone gap filler designed to dissipate heat from EV modules, printed circuit boards, and other heat-generating electronic components. With 2.0 W/m·K thermal conductivity, low cured specific gravity of 1.95, UL 94 V-0 recognition, and a soft compliant cured form, TC-5515 LT helps provide reliable thermal transfer while reducing weight and mechanical stress in battery packs, control units, and electronic modules.
Lightweight thermal gap filling for EV and electronics reliability — TC-5515 LT combines 2.0 W/m·K thermal conductivity, low density, soft compliance, and vertical stability for reliable module cooling.
Once cured, the material remains soft and tacky for easy rework, while providing dielectric insulation, environmental protection, and stress relief against vibration, shock, and thermal cycling.
Designed for EV battery and control unit modules — suitable for transferring heat from EV modules, PCB-mounted components, and power electronics to aluminum housings or heat sinks.
The low-density silicone formulation supports lightweight thermal management while maintaining stable performance across demanding temperature and vibration environments.
2.0 W/m·K Thermal Conductivity • Low Density 1.95 • UL 94 V-0 • -45 °C to 150 °C Operation
Features & Benefits
- 2.0 W/m·K thermal conductivity — supports reliable heat dissipation.
- Low density — cured specific gravity of 1.95 for weight-sensitive designs.
- Room-temperature cure — cures in 360 minutes at 25 °C.
- Heat-accelerated cure — cures in 30 minutes at 80 °C.
- Soft and compliant — provides stress relief in vibration applications.
- Non-flowable after dispense — holds position on flat and vertical surfaces.
- Surface tacky after cure — supports rework after curing and assembly.
- UL 94 V-0 recognition — suitable for flame-rated electronic assemblies.
Typical Applications
- EV battery module thermal management.
- EV control unit modules.
- PCB-to-aluminum housing thermal interfaces.
- Automotive electronics and power modules.
- Component-to-heat-sink gap filling.
- Lightweight electronics thermal management.
- Vibration-sensitive module assemblies.
Thermal Challenges in Lightweight EV Modules
EV battery and control unit modules require thermal materials that can dissipate heat while limiting added weight and protecting sensitive electronics from mechanical stress. DOWSIL™ TC-5515 LT helps address these needs with a low-density silicone gap filler that transfers heat from EV modules, printed circuit boards, and other heat-generating components to aluminum housings or heat sinks.
Engineering Data for DOWSIL™ TC-5515 LT
| Property | DOWSIL™ TC-5515 LT | Condition / Note |
|---|---|---|
| Type | Two-part silicone gap filler | Low density thermally conductive material |
| Mix Ratio | 1:1 | By weight or volume |
| Color | Part A: White Part B: Blue | Typical appearance |
| Mixed Viscosity | 140 Pa·s | At 10 s-1 |
| Thixotropic Index | 3.5 | 1 s-1 / 10 s-1 |
| Working Time | 90 minutes | At 25 °C |
| Specific Gravity, Cured | 1.95 | Low density |
| Thermal Conductivity | 2.0 W/m·K | Hot Disk |
| Cure Time | 360 minutes | At 25 °C |
| Heat-Accelerated Cure | 30 minutes | At 80 °C |
| Hardness | Shore 00 65 | Soft compliant material |
| Dielectric Strength | 19.0 kV/mm | Cured material |
| Volume Resistivity | ≥ 1.0E+13 ohm·cm | Electrical insulation |
| Lap Shear Strength | 0.20 MPa | Aluminum to aluminum |
| Shear Modulus | 0.27 MPa | DMA |
| Minimum BLT | 142 µm at 0.14 MPa 127 µm at 0.42 MPa | Bondline thickness data |
| UL Flame Classification | UL 94 V-0 | Recognized classification |
| Shelf Life | 9 months | At 25 °C |
*Typical properties are not intended for specification writing. Verify performance under actual application, substrate, assembly, compression, cure, and reliability conditions.
Where DOWSIL™ TC-5515 LT Fits
- Battery modules
- Cell-to-plate interfaces
- Thermal management assemblies
- EV control units
- PCB-mounted components
- Aluminum housing interfaces
- Vertical gaps
- Automated dispensing
- Reworkable module assemblies
Mixing, Dispensing & Cure
Mixing
Mix Part A and Part B at a 1:1 ratio by weight or volume. A static mixer is recommended for manual and automated dispensing.
Dispensing
The thixotropic, non-flowable material is designed to remain in position after dispensing, including flat and vertical applications.
Curing
Cures in 360 minutes at 25 °C or can be heat accelerated to 30 minutes at 80 °C. No post-cure is required after cure completion.
How TC-5515 LT Supports EV Module Design
| Design Challenge | DOWSIL™ TC-5515 LT Benefit |
|---|---|
| EV modules require thermal transfer with reduced added weight. | Low specific gravity of 1.95 supports lightweight thermal gap filling. |
| Vibration and thermal cycling can stress sensitive components. | Soft compliant silicone provides stress relief after cure. |
| Thermal material must stay in place during assembly. | Non-flowable behavior supports flat and vertical dispensing conditions. |
| Module assemblies may require serviceability after cure. | Tacky cured surface helps enable easier rework after assembly. |
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