(978) 686-6332  sales@nedc.com

Bergquist GAP PAD® 2500S20: ultra-conformable thermal gap filler for low-pressure assemblies

by | Aug 24, 2025 | Artificial Intelligence, Die Cutting, Electrical Insulators, Thermal Pads, Waterjet Cutting

Bergquist GAP PAD® 2500S20: ultra-conformable thermal gap filler for low-pressure assemblies

If you need a forgiving, fiberglass-reinforced pad that wets out beautifully at very low clamping forces, GAP PAD 2500S20 has been a go-to for years. It sits in the “S-Class” family (the soft, squishy stuff), pairing 2.4 W/m-K conductivity with Shore 00 ~20 softness so it can flow into micro-asperities without over-stressing components. The pad is silicone-based with a fiberglass carrier for tear resistance and stable handling. Typical uses: between processors/ASICs and heat sinks, graphics chips, and any spot where heat must hop across a mechanical gap to a chassis or spreader.

Core specs (quick hit)

  • Thermal conductivity: 2.4 W/m-K (ASTM D5470)

  • Hardness: ~Shore 00 20 (very soft, “S20”)

  • Carrier: fiberglass reinforcement

  • Use temp: −60 to +200 °C (continuous)

  • Dielectric strength: >3 kVAC

  • Inherent tack: natural tack on both sides (“02” option)

  • Flame rating: UL 94 V-0

  • Color: light yellow

Thicknesses, sheets & real-world handling

  • Standard sheet: 8″ × 16″ (0816)

  • Common thicknesses: 0.010″, 0.015″, 0.020″, 0.040″, 0.060″, 0.080″, 0.100″, 0.125″, 0.160″, 0.200″, 0.250″

  • Tack option: 02 = natural tack both sides (great for “stick-in-place” during assembly)

  • “Resultant thickness” matters: pick your thickness based on the compressed gap under your screw/clip load, not the pad’s free thickness. The S-Class modulus is gel-like, so it conforms with very low pressure while maintaining electrical isolation.

How the part numbers are built

Bergquist’s SKU structure makes selection predictable. For example:

GP2500S20-0.040-02-0816

  • GP2500S20 → material family

  • 0.040 → nominal thickness (inches)

  • 02 → natural tack, both sides

  • 0816 → 8″ × 16″ sheet (custom die-cuts often use “00”)

Common, in-stock SKUs include:
GP2500S20-0.020-02-0816, GP2500S20-0.040-02-0816, GP2500S20-0.060-02-0816, GP2500S20-0.080-02-0816, GP2500S20-0.100-02-0816, GP2500S20-0.125-02-0816, GP2500S20-0.160-02-0816, GP2500S20-0.200-02-0816, GP2500S20-0.250-02-0816.

Where GAP PAD 2500S20 fits (and where it doesn’t)

Great for

  • Boards and modules with uneven topography or low allowable clamp loads

  • Clip-mounted sinks, fixed standoffs, plastic bosses—any low-pressure joint

  • Designs needing added dielectric isolation across the gap, without greases or messy cure steps

Maybe not ideal for

  • Extremely high heat flux where you need ≥5–10 W/m-K pads (consider higher-k families)

  • Ultra-tight tolerances requiring very high modulus (this is intentionally soft)

“How much wattage can it handle?” (the engineer’s shortcut)

Pad selection is about temperature rise across the interface, not a fixed “watts rating.” Use the conduction equation:

ΔT ≈ q × R<sub>th,pad</sub>, where R<sub>th,pad</sub> = t / (k·A)

  • t = compressed (“resultant”) thickness (m)

  • k = thermal conductivity (W/m-K) → 2.4 for 2500S20

  • A = contact area (m²)

Example
20 mm × 20 mm contact (A = 0.0004 m²), 1.0 mm resultant thickness (t = 0.001 m):
R<sub>th</sub> ≈ 0.001 / (2.4 × 0.0004) ≈ 1.04 K/W
At 5 W, ΔT ≈ ~5.2 °C across the pad.

Want less ΔT? Increase area, reduce thickness (within your mechanical stack), or step up to a higher-k pad. Also include spreader-to-ambient resistance in your full budget; the pad is just one slice of the thermal stack.

Pro tip: With soft S-Class pads, compression raises the effective contact area and cuts R<sub>th</sub>. Aim for a realistic clamp load so you achieve the intended resultant thickness without bowing the PCB.

Design & DFM notes

  • Die-cut friendliness: Fiberglass carrier resists stretch and tearing during kiss-cutting and pick-and-place. Keep minimum web widths ≥ the pad’s thickness for yield.

  • Surface prep: Finger oils matter. Keep copper, anodized aluminum, and ENIG pads clean; the inherent tack will do the rest.

  • Electrical safety: With >3 kVAC breakdown, 2500S20 adds a comfortable isolation margin in most low-voltage electronics; verify creepage/clearance separately.

Spec table (selected)

  • k: 2.4 W/m-K

  • Hardness: Shore 00 20

  • Density: 3.1 g/cc

  • Heat capacity: 1.0 J/g-K

  • Dielectric constant (1 kHz): ~6.6

  • Volume resistivity: 10¹¹ Ω-m

  • Use temp: −60…+200 °C

  • UL: 94 V-0

Ordering quick list (popular SKUs)

  • GP2500S20-0.020-02-0816

  • GP2500S20-0.040-02-0816

  • GP2500S20-0.060-02-0816

  • GP2500S20-0.080-02-0816

  • GP2500S20-0.100-02-0816

  • GP2500S20-0.125-02-0816

  • GP2500S20-0.160-02-0816

  • GP2500S20-0.200-02-0816

  • GP2500S20-0.250-02-0816

Bottom line

If your design tolerates ~2.4 W/m-K and you prioritize low clamp force + high conformity, GAP PAD 2500S20 aka GAP PAD TGP 2400 is a reliable, production-friendly pick that simplifies assembly while keeping ΔT across the gap in check. For higher heat flux, step up in conductivity—or shrink the gap and grow the area to keep the math on your side.

Share this Article: