COOLTHERM 6735
Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others
Main features
- Eight-Hour Working Window
- 55 to 205 deg C Service Range
- Reversion-Resistant Addition-Cure System
Product Description
Circalok™ 6735 Silicone Encapsulant is a clear, two-component, addition-cure silicone system for potting and encapsulation applications requiring a flexible cured material and high-temperature service. The mixed material has a typical 3,500 cP viscosity at 25°C, an eight-hour working life, and a 10:1 resin-to-hardener mix ratio by weight. It cures for 4 hours at 65°C, with an overnight post-cure at 85°C recommended for optimum properties, particularly in large volumes. Typical cured properties include 40 Shore A hardness, 750 psi tensile strength, 150% elongation at break, 450 V/mil dielectric strength, and operation from -55°C to +205°C.
Key features
- Clear, two-part addition-cure silicone encapsulant
- Low 3,500 cP mixed viscosity for flow around components and into cavities
- Eight-hour working life at 25°C
- Broad documented operating range from -55°C to +205°C
- Typical volume resistivity of 1 × 1014 ohm-cm and dielectric strength of 450 V/mil
- Adheres to most substrates without primer, subject to substrate validation
- Reversion-resistant, non-corrosive high-temperature silicone system
Applications
- Potting and encapsulation of electrical and electronic assemblies
- High-temperature assemblies requiring a flexible silicone encapsulant
- Large-volume or deep-section encapsulation using controlled heat cure and post-cure
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Physical Properties
Mechanical Properties
Electrical Properties
Thermal Properties
Additional Information
Circalok™ 6735 Silicone Encapsulant
A clear, low-viscosity, two-component silicone system for potting and encapsulation where flexible electrical insulation and high-temperature operation are required. Circalok 6735 provides an eight-hour working life for meter/mix/dispense processing and cures to a 40 Shore A elastomer after controlled heat cure.
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Component and mixed-material properties
Both components and the mixed system are clear liquids. The resin provides the main viscosity, while the lower-viscosity hardener is incorporated at a controlled 10:1 ratio by weight. All values are typical.
| Property | 6735 A resin | 6735 B hardener | Mixed material |
|---|---|---|---|
| Appearance | Clear liquid | Clear liquid | Clear liquid |
| Viscosity at 25°C | 3,700 cP | 200 cP | 3,500 cP |
| Specific gravity | 1.00 | 1.00 | 1.00 |
| Working life at 25°C | 8 hours after mixing | ||
Stir, meter at 10:1, dispense, and heat cure
Thoroughly stir each component separately, then combine Circalok 6735 A resin and Circalok 6735 B hardener at 10:1 by weight. Apply using automatic meter/mix/dispense equipment. Keep the material away from surfaces containing cure-inhibiting amines, sulfur, or tin salts.
- Where substrate compatibility is uncertain, apply a test patch and allow it to complete the normal cure.
- Cure for 4 hours at 65°C after the material reaches the target temperature.
- Allow for oven ramp rate and the thermal mass of parts and large encapsulated volumes.
- An overnight post-cure at 85°C is recommended for optimum properties, especially for large volumes.
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Restore each component to a uniform state before combining.
Control the resin-to-hardener ratio and mix thoroughly without unnecessary air entrainment.
Apply within the eight-hour working life using validated meter/mix/dispense equipment.
Cure 4 hours at 65°C; use the recommended overnight 85°C post-cure where optimum properties are required.
Storage and handling
Each component has a six-month shelf life from the date of manufacture when stored at 25°C in its original, unopened container. Before handling, review the current product label and applicable safety documentation. Circalok 6735 is for trained industrial or commercial personnel and is not intended for household or consumer use.
Mechanical, thermal, and electrical properties
The cured values below are typical laboratory properties. The datasheet identifies a 2-hour cure at 150°C for the cured-property specimen, so these values should not be assumed to represent every 65°C production cure without validation.
| Property | Typical value | Context |
|---|---|---|
| Hardness | 40 Shore A | Flexible cured elastomer. |
| Tensile strength | 750 psi | Bulk tensile property. |
| Elongation at break | 150% | Bulk tensile specimen property. |
| Thermal conductivity | 0.2 W/m·K | Bulk cured-material property; the product is not positioned as a thermally conductive encapsulant. |
| Volume resistivity at 25°C | 1 × 1014 ohm-cm | ASTM D257. |
| Dielectric strength | 450 V/mil | Test property, not an assembled-system working-voltage rating. |
| Dielectric constant | 3.0 at 100 Hz | Frequency-specific bulk property. |
| Dissipation factor | 0.001 at 100 Hz | Frequency-specific bulk property. |
Flexible, high-temperature electrical and electronic encapsulation
Circalok 6735 is positioned within Parker’s electronic potting and encapsulation portfolio for assemblies requiring a clear, flexible silicone and high-temperature operation. Validate cure compatibility, adhesion, section size, electrical design, and environmental exposure in the complete assembly.
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Evaluate Circalok™ 6735 for your encapsulation process
Krayden can help review component compatibility, cure-inhibition risk, section volume, metering and dispensing, cure and post-cure profiles, adhesion, dielectric requirements, and high-temperature validation for Circalok™ 6735.
