Protect® 1500FG
Arlon Protect 1500FG is a fiberglass-supported cured silicone rubber insulator sheet engineered for LED and power applications, delivering 1.5 W/m·K thermal conductivity and > 19 kV/mm dielectric strength. The construction is offered at 7 – 20 mils (0.18 – 0.51 mm) thickness with thermal impedance of 1.9 × 10⁻⁴ m²·K/W at 40 PSI across an operating range of -100°C to +204°C. UL listed (QMFZ2.E54153) with a UL 94 V-0 flame rating, RTI 150°C/150°C, RoHS compliant, and free of halogenated flame retardants.
Key Properties
- Thermal Conductivity: 1.5 W/m·K (ASTM D5470)
- Thermal Impedance @ 40 PSI: 1.9 × 10⁻⁴ m²·K/W / 0.3 in²·°C/W (ASTM D5470)
- Dielectric Strength: > 19 kV/mm / > 500 V/mil (ASTM D149)
- Hardness: 77 Shore A (ASTM D2240)
- Operating Range: -100°C to +204°C
- Thickness Range: 0.18 – 0.51 mm (7 – 20 mils)
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Color | Mauve or Gray | Visual |
| Thickness | 7 – 20 mils / 0.18 – 0.51 mm | ASTM D374 |
| Construction | Supported | — |
| Supporting Material | Fiberglass | — |
Mechanical Properties
| Property | Value | Test Method |
| Hardness | 77 Shore A | ASTM D2240 |
| Tensile Strength | 850 PSI / 5.9 MPa | ASTM D412 |
| Elongation, Machine Direction | 4% | ASTM D412 |
| Elongation, 45° Warp and Fill | 20% | ASTM D412 |
Thermal Properties
| Property | Value | Test Method |
| Thermal Conductivity | 0.87 Btu/(hr·ft·°F) / 1.5 W/m·K | ASTM D5470 |
| Thermal Impedance @ 40 PSI | 0.3 in²·°C/W / 1.9 × 10⁻⁴ m²·K/W | ASTM D5470 |
| Glass Transition Temperature | -180°F / -118°C | ASTM D3418 |
| Operating Range | -150 to +400°F / -100 to +204°C | — |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Strength (kVac) | > 500 V/mil / > 19 kV/mm | ASTM D149 |
Flame & Fire Performance — UL Certification (QMFZ2.E54153)
| Property | Value | Test Method |
| Flammability Rating | V-0 | UL 94 |
| RTI, Mechanical | 300°F / 150°C | UL 746 |
| RTI, Electrical | 300°F / 150°C | UL 746 |
| Hot Wire Ignition (HWI) | 4 @ 0.17 mm / 3 @ 0.51 mm | UL 746 |
| High Current Arc Ignition (HAI) | 3 @ 0.17 mm / 2 @ 0.51 mm | UL 746 |
Standard Sizes / Supply
| Property | Value | Test Method |
| Standard Roll | 16 in. × 125 LY | — |
| Converted Formats | Slit widths, cut pads, and die cuts | — |
| Custom Sizes | Available upon request | — |
Storage
| Property | Value | Test Method |
| Shelf Life | 5 years from date of manufacture | — |
| Storage Temperature | 25°C ± 3°C | — |
Compliance
- UL 94 — Compliant (V-0)
- UL 746 — Compliant (RTI 150°C/150°C, HWI, HAI)
- UL Listed — QMFZ2.E54153
- RoHS — Compliant
- Halogen-Free Flame Retardants
- Thermally coupling power transistors to heat sinks with electrical isolation
- Thermally coupling LED light modules to heat sinks
- LED PCB electrical isolation under mechanical fasteners
- Power transistor isolation in clip-, spring-, or screw-mounted assemblies
- Low-pressure thermal pad service where wet-out at low fastener load is critical
Common industries: LED lighting, power electronics, and thermal management for fastener-mounted assemblies.
Arlon Protect 1500FG is an insulator sheet composed of cured silicone rubber with functional additives, supported by a fiberglass substrate, and formulated to deliver a balance of thermal, mechanical, and electrical performance for LED and power applications. The material is softer and more compliant than competitive insulators, wetting out and conforming to surface topography at lower fastener pressures to maximize contact area, improve thermal-path consistency, and reduce hot spots.
Protect insulators are designed for use with mechanical fasteners — clips, springs, or screws — to electrically isolate an LED PCB or power transistor from the heat sink while transferring heat.
Mechanical performance includes 77 Shore A hardness, 850 PSI / 5.9 MPa tensile strength, 4% elongation in the machine direction, and 20% elongation at 45° warp and fill. Thermally, the material delivers 1.5 W/m·K (0.87 Btu/(hr·ft·°F)) thermal conductivity, thermal impedance of 0.3 in²·°C/W (1.9 × 10⁻⁴ m²·K/W) at 40 PSI per ASTM D5470, a glass transition temperature of -118°C, and an operating range of -100°C to +204°C (-150 to +400°F).
Electrically, the dielectric strength is > 19 kV/mm per ASTM D149. Under UL certification QMFZ2.E54153, the product is rated UL 94 V-0 with RTI 150°C for both mechanical and electrical applications, Hot Wire Ignition (HWI) of 4 at 0.17 mm and 3 at 0.51 mm, and High Current Arc Ignition (HAI) of 3 at 0.17 mm and 2 at 0.51 mm per UL 746. The product is RoHS compliant and free of halogenated flame retardants.
Standard format is 16 in. × 125 LY rolls, with slit widths, cut pads, and die cuts available; shelf life is 5 years from date of manufacture at 25°C ± 3°C.
Compliant with UL 94 V-0, UL 746 (RTI 150°C/150°C, HWI, HAI), UL listing QMFZ2.E54153, and RoHS, with halogen-free flame retardants.
What differentiates Protect 1500FG from the Secure thermal interface adhesives or competitive insulators?
Protect 1500FG is a cured silicone insulator pad designed for mechanical-fastener service — clips, springs, or screws — rather than a bonding adhesive like the Secure family. The fiberglass-supported construction is softer and more compliant than competitive insulators, wetting out at lower pressures to improve contact area and thermal-path consistency. It is offered across a 0.18 – 0.51 mm thickness range, is RoHS compliant with halogen-free flame retardants, and carries full UL 746 short- and long-term ratings (RTI 150°C/150°C, HWI, HAI) in addition to UL 94 V-0.
Why is dielectric strength important for this application?
Protect 1500FG's primary function is to electrically isolate an LED PCB or power transistor from the heat sink while transferring heat across the interface. The dielectric strength of > 19 kV/mm per ASTM D149 — paired with UL RTI 150°C/150°C, V-0 flame rating, and the HWI/HAI ignition resistance ratings — establishes the voltage withstand and ignition behavior required to safely separate a powered component from a grounded heat sink under continuous service.
What is the operating temperature range for Protect 1500FG?
The operating range is -100°C to +204°C (-150 to +400°F), with a glass transition temperature of -118°C. The UL 746 relative thermal index is 150°C for both mechanical and electrical applications.
Is Protect 1500FG suitable for UL-rated, RoHS, and halogen-free environments?
Yes. The material is UL listed under QMFZ2.E54153 with a UL 94 V-0 flammability rating, RTI 150°C/150°C, and full UL 746 HWI/HAI ratings. It is also RoHS compliant and free of halogenated flame retardants, making it suitable for LED, power transistor, and regulated electronics assemblies.
How should Protect 1500FG be specified?
Specify grade (Arlon Protect 1500FG), thickness (7 – 20 mils / 0.18 – 0.51 mm), color (Mauve or Gray), part geometry (die-cut, cut pad, slit roll, or 16 in. × 125 LY standard roll), dielectric performance requirements, UL compliance (UL 94 V-0, QMFZ2.E54153 RTI 150°C/150°C, HWI/HAI ratings), and finished format.
