Not every thermal interface demands a premium, ultra-high-conductivity gap filler. In many mainstream electronics applications, the design challenge is finding a pad that balances solid thermal performance with the compressibility and conformability needed to fill uneven gaps — all at a cost that does not strain the bill of materials. The PK504 thermal pad from LiPOLY is built for exactly that space. It belongs to LiPOLY’s General Series, a product family engineered to deliver reliable thermal transfer for high-volume applications where the thermal budget does not justify the Extreme Series price tag.
As part of the General Series, the PK504 is positioned as a workhorse thermal interface material. It delivers 5.0 W/m·K of thermal conductivity — a solid mid-range figure that covers the majority of consumer and automotive electronics cooling requirements. What sets it apart from commodity pads at this conductivity level is its combination of natural surface tack, low thermal impedance, and a hardness rating of 50 Shore OO that gives it excellent conformability without requiring high clamping force.
PK504 Specifications
The PK504 is a silicone-based thermal gap filler rated at 5.0 W/m·K (ASTM D5470). The key performance figure for designers is the thermal impedance: 0.415 °C-in²/W at 10 psi of contact pressure, improving to 0.307 °C-in²/W at 50 psi. That impedance range reflects the material’s ability to wet out against mating surfaces under modest clamping loads while continuing to improve as pressure increases. The natural surface tack — available in 2-side or 1-side configurations — helps the pad stay in position during assembly, which simplifies process handling without requiring a separate adhesive layer.
With a hardness of 50 Shore OO (ASTM D2240), the PK504 is soft enough to conform to surface irregularities and bridge coplanarity gaps between a component and its heatsink. That softness, combined with a density of 3.0 g/cm³, gives the material a balance of compressibility and structural integrity that holds up across a wide operating temperature range of -60°C to 180°C.
Typical properties:
- Thermal conductivity: 5.0 W/m·K (ASTM D5470)
- Thermal impedance: 0.415 °C-in²/W @ 10 psi; 0.307 °C-in²/W @ 50 psi
- Surface tack: 2-side / 1-side, option 2
- Thickness: Customized (ASTM D374)
- Density: 3.0 g/cm³ (ASTM D792)
- Hardness: 50 Shore OO (ASTM D2240)
- Operating temperature: -60°C to 180°C
- Dielectric breakdown: 12 KV/mm (ASTM D149)
- Color: Gray
- ROHS / REACH compliant
For complete technical specifications, download the PK504 datasheet.
Applications Where PK504 Excels
The 5.0 W/m·K rating and 50 Shore OO hardness make the PK504 well-suited for a broad range of consumer, telecom, and automotive thermal applications where moderate heat loads meet uneven surface topography:
- Notebook computers where CPU and GPU heat must transfer to the chassis or heat pipe assembly
- Heat pipe assemblies requiring a conformable interface between the pipe and the heat source
- Memory modules that need thermal contact between DRAM packages and thermal rails or spreaders
- TV hardware with multiple thermal zones and moderate heat flux across large surface areas
- Automotive electronic devices where thermal cycling and vibration demand a compliant interface
- Mobile devices with tight gap tolerances and low clamping force
- High-speed mass storage drives where SSD controllers need consistent thermal contact
- Set-top boxes and streaming hardware with passive cooling architectures
- IP cameras requiring stable thermal performance in compact enclosures
- 5G base stations and infrastructure where long-term reliability under thermal stress is critical
- EV electric vehicle control units and battery management systems
Because the PK504 is a silicone-based pad with a dielectric breakdown of 12 KV/mm (ASTM D149), it provides reliable electrical isolation between live components and grounded heatsinks. That insulation capability removes the need for a separate insulating layer in the thermal stack, which simplifies assembly and reduces the total number of interfaces in the thermal path — each of which would add its own thermal resistance.
PK504 and the LiPOLY General Series
The PK504 is part of LiPOLY’s General Series, a family of thermal gap fillers designed to provide solid thermal performance at a price point suited to high-volume production. The General Series shares the same silicone platform as LiPOLY’s Extreme Series but targets applications where the thermal budget does not require 11–20 W/m·K conductivity. For many consumer electronics, the 5.0 W/m·K conductivity of the PK504 is more than sufficient to move heat from the source to the sink, especially when the pad’s low impedance and conformability are factored into the overall thermal resistance calculation.
Within the PK Series, the PK504 sits as a mid-range option. Higher-conductivity variants in the same series step up thermal performance for applications that demand it, while the PK504 covers the broad middle ground where cost and performance need to balance. That consistency in material family means engineers can prototype with the PK504 and, if thermal testing reveals higher heat loads than expected, move up within the same series without redesigning the interface geometry.
For applications that need more thermal headroom, LiPOLY’s Extreme Series offers a step-change in performance. The T-work7000 delivers 11.0 W/m·K with an impedance of 0.223 °C-in²/W, the T-work8000 reaches 15.0 W/m·K at 0.185 °C-in²/W, and the T-work9000 tops the lineup at 20.0 W/m·K with just 0.110 °C-in²/W of impedance. The PK504 covers the cost-sensitive end of that spectrum where 5.0 W/m·K is the right tool for the job.
Custom Die-Cut Supply Through NEDC
NEDC converts PK504 into custom-configured parts using die-cutting, waterjet cutting, and laser cutting depending on the material thickness and part geometry. The pad arrives at your production line as a ready-to-place component, sized to the housing, PCB feature, or heatsink pocket it was designed for — no secondary cutting or hand fitting required.
The PK504 is available in roll form, sheet form, or as individual die-cut parts. Kiss-cut formats on tape-and-reel are also available for automated pick-and-place assembly, which matters in high-volume production environments. NEDC’s engineering team can advise on optimal thickness selection based on the available gap dimension and clamping force in the assembly, and works directly with LiPOLY to source material configured to the specific application.
For a complete overview of NEDC’s thermal pad offerings, visit thermal pads at NEDC.
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Need a custom PK504 die-cut part? Contact NEDC with your specifications.