BERGQUIST® SIL PAD TSP 900 Silicone / Fiberglass Thermally Conductive Insulator Pad (formerly SIL-PAD 400)
BERGQUIST SIL PAD TSP 900 is a silicone rubber / fiberglass composite thermally conductive insulator pad — the original Sil-Pad material — with a thermal conductivity of 0.9 W/(m·K) and a thermal impedance of 1.13°C·in²/W at 50 psi (0.007″ thickness). The pad delivers dielectric breakdown voltage of 3,500 to 4,500 Vac across an operating temperature range of -60°C to +180°C, with documented UL 94 V-0 flammability. The reinforcing fiberglass provides excellent cut-through resistance, and the material is non-toxic and resists damage from cleaning agents.
Key Properties
- Thermal Conductivity: 0.9 W/(m·K) (ASTM D5470)
- Thermal Impedance @ 50 psi (0.007″): 1.13°C·in²/W
- Dielectric Breakdown Voltage: 3,500 to 4,500 Vac (ASTM D149)
- Hardness: 85 Shore A (ASTM D2240)
- Operating Temperature Range: -60°C to +180°C
Total Thickness: 0.178 mm, 0.229 mm
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Technology | Silicone | — |
| Appearance | Gray | — |
| Reinforcement Carrier | Fiberglass | — |
| Total Thickness | 0.178 mm, 0.229 mm | ASTM D374 |
| Operating Temperature Range | -60°C to +180°C | — |
Mechanical Properties
| Property | Value | Test Method |
| Hardness, Shore A | 85 | ASTM D2240 |
| Breaking Strength | 5 kN/m | ASTM D1458 |
| Elongation, 45° to Warp and Fill | 54% | ASTM D412 |
| Tensile Strength | 20 MPa | ASTM D412 |
Thermal Properties
| Property | Value | Test Method |
| Thermal Conductivity | 0.9 W/(m·K) | ASTM D5470 |
Thermal Performance vs. Pressure — 0.007″ Thickness
| Property | Value | Test Method |
| TO-220 Thermal Performance @ 10 psi | 6.62 °C/W | ASTM D5470 |
| Thermal Impedance @ 10 psi | 1.82 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 25 psi | 5.93 °C/W | ASTM D5470 |
| Thermal Impedance @ 25 psi | 1.42 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 50 psi | 5.14 °C/W | ASTM D5470 |
| Thermal Impedance @ 50 psi | 1.13 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 100 psi | 4.38 °C/W | ASTM D5470 |
| Thermal Impedance @ 100 psi | 0.82 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 200 psi | 3.61 °C/W | ASTM D5470 |
| Thermal Impedance @ 200 psi | 0.54 °C·in²/W | ASTM D5470 |
Thermal Performance vs. Pressure — 0.009″ Thickness
| Property | Value | Test Method |
| TO-220 Thermal Performance @ 10 psi | 8.51 °C/W | ASTM D5470 |
| Thermal Impedance @ 10 psi | 2.34 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 25 psi | 7.62 °C/W | ASTM D5470 |
| Thermal Impedance @ 25 psi | 1.83 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 50 psi | 6.61 °C/W | ASTM D5470 |
| Thermal Impedance @ 50 psi | 1.45 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 100 psi | 5.63 °C/W | ASTM D5470 |
| Thermal Impedance @ 100 psi | 1.05 °C·in²/W | ASTM D5470 |
| TO-220 Thermal Performance @ 200 psi | 4.64 °C/W | ASTM D5470 |
| Thermal Impedance @ 200 psi | 0.69 °C·in²/W | ASTM D5470 |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Breakdown Voltage | 3,500 to 4,500 Vac | ASTM D149 |
| Dielectric Constant @ 1,000 Hz | 5.5 | ASTM D150 |
| Volume Resistivity | 1 × 10¹¹ ohm-meter | ASTM D257 |
Flame & Fire Performance
| Property | Value | Test Method |
| Flammability Rating | V-0 | UL 94 |
Compliance
- UL 94 — Compliant (V-0)
- Power supply insulator pads between power devices and heat sinks
- Automotive electronics thermal interface insulation
- Power semiconductor electrical isolation
- Motor control thermal interface
- Cut-through-resistant insulator pads for fiberglass-reinforced service
Common industries: power electronics, automotive electronics, motor controls, and power semiconductor manufacturing.
BERGQUIST SIL PAD TSP 900 is the original Sil-Pad thermally conductive insulator — a silicone rubber and fiberglass composite engineered to electrically isolate power sources from heat sinks while transferring heat across the interface. The pliable surface allows complete contact and excellent heat dissipation, and notably the material’s thermal resistance improves with age. The reinforcing fiberglass carrier provides excellent cut-through resistance, and the construction is non-toxic and resists damage from common cleaning agents.
Mechanical performance includes 85 Shore A hardness, 5 kN/m breaking strength, 54% elongation at 45° to warp and fill, and 20 MPa tensile strength. Electrically, the dielectric breakdown voltage is 3,500 to 4,500 Vac, dielectric constant at 1,000 Hz is 5.5, and volume resistivity is 1 × 10¹¹ ohm-meter.
Thermally, the material delivers 0.9 W/(m·K) thermal conductivity, with TO-220 thermal performance ranging from 6.62°C/W at 10 psi to 3.61°C/W at 200 psi at 0.007″ thickness, and 8.51°C/W at 10 psi to 4.64°C/W at 200 psi at 0.009″ thickness. Operating temperature range is -60°C to +180°C, and the material is UL 94 V-0 flame retardant. Total thickness options are 0.178 mm and 0.229 mm.
Compliant with UL 94 V-0 (flame retardancy) and the listed ASTM test methods: ASTM D374, D2240, D1458, D412, D149, D150, D257, and D5470.
What differentiates SIL PAD TSP 900 from higher-performance SIL PAD TSP grades?
SIL PAD TSP 900 is the original Sil-Pad material — a fiberglass-reinforced silicone insulator with 0.9 W/(m·K) thermal conductivity and 3,500 to 4,500 Vac dielectric breakdown voltage, offered at 0.178 mm and 0.229 mm thickness. It is positioned as the general-purpose Sil-Pad grade, with higher-conductivity alternatives in the line (TSP 1600S, 1800ST, 3500) and a Kapton-reinforced cost-down alternative for ceramic insulators (TSP K1300). The defining differentiators of TSP 900 are excellent cut-through resistance from the fiberglass reinforcement, UL 94 V-0 flame retardancy, resistance to common cleaning agents, and the documented characteristic that thermal resistance improves with age.
Why does thermal conductivity matter in material selection?
The function of a Sil-Pad insulator is to transfer heat from a power device to a heat sink while keeping the two electrically isolated. Thermal conductivity sets the bulk heat transport, and thermal impedance — which includes interfacial resistance and is pressure-dependent — determines real-world performance. TSP 900 delivers 0.9 W/(m·K) and 1.13°C·in²/W at 50 psi (0.007"), suitable for general-purpose insulator service. Higher-conductivity alternatives in the TSP family fit applications where lower thermal impedance is required.
What is the operating temperature range for SIL PAD TSP 900?
The operating temperature range is -60°C to +180°C.
Is SIL PAD TSP 900 suitable for flame-rated electronics environments?
Yes. The material is rated UL 94 V-0 for flammability, making it suitable for power supply, automotive electronics, and other UL-rated electronics assemblies that require flame-retardant thermal interface insulation.
How should SIL PAD TSP 900 be specified?
Specify grade (BERGQUIST SIL PAD TSP 900), thickness (0.178 mm or 0.229 mm), part geometry (sheet, roll, die-cut, or kiss-cut), adhesive option (with or without pressure-sensitive adhesive), dielectric and thermal impedance requirements at target pressure, UL 94 V-0 flame rating, and finished format.
