Thermal interface materials: Critical heat-transfer frontier in semiconductor packaging

The next generation of Thermal Interface Materials (TIMs) offer the opportunity to gain a quantum leap in thermal efficiency, reliability, and market growth. IDTechEx research finds the market size of next-generation TIM1 and TIM1.5 for advanced semiconductor packaging will exceed at a CAGR of 31% from 2026 to 2036.

As semiconductor packaging surges toward 2.5D and 3D architectures, managing thermal resistance at the interface becomes mission critical. With localized power densities surpassing 600 W/cm² for advanced semiconductors, traditional thermal interface materials no longer suffice. 

Enter the next generation of Thermal Interface Materials (TIMs), and the opportunity to gain a quantum leap in thermal efficiency, reliability, and market growth. IDTechEx's research in the report "Thermal Management for Advanced Semiconductor Packaging 2026-2036: Technologies, Markets and Opportunities" reveals the commercial opportunities and technical innovations for next-generation TIMs for advanced semiconductor packaging. 

TIM1 to TIM1.5 evolution: Game-changer
Innovations in TIM architecture are transforming heat transfer. The advanced semiconductor packaging industry is shifting from the classic two-layer system (TIM1 + TIM2) to a unified TIM1.5 layer, designed to collapse thermal path length and eliminate interfaces, critical for stacked die assemblies.

* Liquid Metal Alloys (Phase-Change Metal Alloy TIMs), solid at ambient but molten in operation, deliver ultra-low interfacial resistance and high conductivity, adaptable to TIM1.5 use.

* Indium-based TIMs offer thermal conductivities up to ~86 W/m·K, with melting points (~157 °C) ideal for bonding, minimal void formation, and excellent mechanical conformity.

* Graphene-aligned pads developed by Hitachi Chemical boast >20 W/m·K through-plane conductivity under moderate pressures (~20 psi), a significant leap over polymer greases.

Highlights
* Liquid-metal/indium sandwich TIMs deliver a contact resistance as low as 0.036 cm²·K/W at 50 psi, outperforming high-end thermal pads and enduring ≥200 temperature cycles with minimal performance loss.

* Pure indium foil (~0.05 mm thick) achieves around 84 W/m·K, remains pliable from cryogenic to high-temperature ranges, and remains operational across -273 °C to ~155 °C.

* Graphene-aligned TIMs using vertically oriented fillers offer >20 W/m·K across thickness, but sustaining low contact resistance demands sufficient pressure (>20 psi) and material compliance.

* Graphene composites can boost conventional greases by a factor of ~17× in thermal conductivity even at modest filler loading (5-10 vol %), with interface resistance (~3-4 mm²·K/W) at 330 K rivaling commercial TIMs.

Why TIM1.5 is a strategic differentiator?
TIM1.5 isn't just a material, it's a performance philosophy:

* Dramatically lowers interfacial thermal resistance by eliminating layer transitions.
* Enables die-to-spreader efficiency critical in high-density multi-chip modules.
* Commands higher unit value; early adopters report 3-5× price premiums over conventional TIMs, unlocking margin expansion. (Industry estimate)

Combined with growing thermal loads, driven by high-bandwidth memory, AI accelerators, and stacked die, the TIM market (TIM1 + TIM1.5) is forecast to reach US$500 million by 2036, signaling a robust commercial opportunity. (IDTechEx)

Engineering considerations and market enablers
Contact quality: High k-value TIMs underperform if interface contact is poor—pressure, surface finish, and voiding are critical. Optimizing contact area and mechanical compliance dramatically reduce Rₙ.

Reliability: Advanced TIMs like LM sandwiches endure hundreds of thermal cycles and operational hours with sustained performance.

Regulatory compliance: RoHS and materials certification (e.g., UL 94 rating) can limit the adoption of certain metal-based TIMs, such as indium and Ga alloys, which face regulatory scrutiny in specific regions.

TIM frontier
Advanced TIMs, especially TIM1.5, are not incremental enhancements but foundational enablers of 3D semiconductor packing and ultra-high-performance chips. 

However, despite TIM1.5  being widely used in advanced semiconductor packaging, such as B200 from Nvidia, IDTechEx learned that there are still technical challenges, and the industry is still transitioning from TIM1+TIM2 with lidded design to TIM1.5 with lidless design.

-- Yulin Wang, Senior Technology Analyst, IDTechEx, USA.