POS7-1467
Enhancing Thermal Conductivity of Non-Conductive Films through Freeze-Cast Alumina Filler Network Formation
Topic
S7. Innovations in Polymeric Composites: From Design and Processing to Industrial Applications
When and Where
Oct 1, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Jinkee HONG
Ki Su KIM
Presenter(s)
Minwook Jeon (Seoul National University)
Co-Author(s)
Abstract
As semiconductor device miniaturization approaches its physical limits, three-dimensional integration and advanced packaging have become essential for high-performance devices. Non-conductive films (NCFs) are key materials for inter-chip bonding in flip-chip and through-silicon via (TSV)-based stacking structures for high bandwidth memory (HBM). However, polymer resins used in NCFs have low thermal conductivity of 0.2–0.3 W/mK, limiting heat dissipation and reliability. Commercial NCFs also remain at approximately 0.45 W/mK, requiring improved thermal management.
In this study, a thermally conductive epoxy-based NCF was developed for low-temperature stacking. To suppress premature curing at 50–70 °C, a thermosetting epoxy resin with an imidazole-based curing agent was used. DSC confirmed a curing degree below 10%, demonstrating processability. Electrically insulating α-phase aluminum oxide nanoparticles with a particle size of 500 nm were uniformly dispersed in the epoxy matrix to fabricate an approximately 50 μm-thick NCF. The film containing 42 vol% aluminum oxide exhibited a thermal conductivity of 1.28 W/mK. Although higher than that of commercial NCFs, the value remained limited because of the random filler distribution.
To overcome this limitation, a continuous filler network was formed by freeze casting. An aqueous aluminum oxide suspension was directionally frozen, and ice crystals aligned the particles into an interconnected inorganic framework. After freeze-drying and sintering, the alumina structure was polished and infiltrated with epoxy resin under vacuum. The resulting composite achieved a thermal conductivity of 2.41 W/mK at only 26 vol% aluminum oxide, approximately half the filler content of the randomly dispersed composite. These results show that continuous inorganic filler networks form efficient thermal pathways and can improve heat dissipation and reliability in high-density 3D semiconductor packaging.
In this study, a thermally conductive epoxy-based NCF was developed for low-temperature stacking. To suppress premature curing at 50–70 °C, a thermosetting epoxy resin with an imidazole-based curing agent was used. DSC confirmed a curing degree below 10%, demonstrating processability. Electrically insulating α-phase aluminum oxide nanoparticles with a particle size of 500 nm were uniformly dispersed in the epoxy matrix to fabricate an approximately 50 μm-thick NCF. The film containing 42 vol% aluminum oxide exhibited a thermal conductivity of 1.28 W/mK. Although higher than that of commercial NCFs, the value remained limited because of the random filler distribution.
To overcome this limitation, a continuous filler network was formed by freeze casting. An aqueous aluminum oxide suspension was directionally frozen, and ice crystals aligned the particles into an interconnected inorganic framework. After freeze-drying and sintering, the alumina structure was polished and infiltrated with epoxy resin under vacuum. The resulting composite achieved a thermal conductivity of 2.41 W/mK at only 26 vol% aluminum oxide, approximately half the filler content of the randomly dispersed composite. These results show that continuous inorganic filler networks form efficient thermal pathways and can improve heat dissipation and reliability in high-density 3D semiconductor packaging.
