Spherical Aluminum Nitride Fillers for Heat‐Conducting Plastic Packages

Abstract

It is necessary for encapsulants to have not only a suitable coefficient of thermal expansion (CTE) compatible to IC devices and a low dielectric constant to reduce the device propagation delay, but also a high thermal conductivity to dissipate large amounts of heat from power-hungry, high-speed IC and highdensity packages. Fillers such as silica have been mixed with polymers to improve their properties. Aluminum nitride (AlN) is considered as an alternative one, because it has a higher theoretical thermal conductivity of B320 W/mK 1 , a compatible CTE with silicon chips and a low dielectric constant. Commercial AlN fillers are angular in shape, because they are prepared via grinding coarse AlN powders synthesized by direct nitridation of aluminum metal and classification. The angular AlN are not expected to have high fluidity when mixed with polymers and hence low packing density. Recently, we successfully obtained single-crystalline spherical AlN fillers. Furthermore, polymer composites filled with the spherical AlN showed excellent thermal conductivity (48 W/mK) as encapsulants for dissipating the heat generated in electronic devices.

Ultrahigh Thermal Conductivity of Interface Materials by Silver‐Functionalized Carbon Nanotube Phonon Conduits

“…[19,27,28] The electrical and thermal transport properties of nAg-MWNT-Ag-flake-epoxy and Ag-flake-epoxy TIMs are compared as a function of the curing duration ( Figure 3). As shown in Figure 3a, the σ of nAgMWNT-Ag-flake-epoxy TIMs was [3] orange open up-pointing triangle (silver nanoparticle 45 vol%), [6] blue open down-pointing triangle (aluminum nitride 74 vol%), [7] dark cyan open diamond (iodine-treated silver 35 vol%), [8] wine open star (silver epoxy plus graphene 5 vol%), [9] violet open pentagon (copper nanowire arrays 25 vol%), [10] magenta open left-pointing triangle (graphite 25 vol%), [11] dark yellow open right-pointing triangle (aligned MWNT 16.7 vol%), [12] navy open hexagon (MWNT 25 vol% plus graphene 25 vol%), [13] pink open inverted triangle (silver 70 vol% plus MWNT 3.1 vol%). [33] Half-filled symbols: olive half-filled pentagon (boron nitride nanosheet 50 vol%), [34] purple half-filled hexagon (carbon nanosheet 33 vol%).…”

“…[14,15] TIMs can be classified into two categories. Electrically conducting TIMs with metal or nanocarbon fillers provided generally higher κ than electrically insulating TIMs with ceramic fillers because additional thermal transport could be realized by electrons: [6][7][8][9][10][11][12][13] ele l at lat…”

Thermal Conductivity of Nanoparticles Filled Polymers

“…Being aware of the high electrical conductivity of metallic particles, several ceramic materials such as aluminum nitride (AlN), boron nitride (BN), silicon carbide (SiC) and beryllium oxide (BeO) gained more attention as thermally conductive fillers due to their high thermal conductivity and electrical resistivity (Nu et al, 2008) and (Ishida & Rimdusit, 1998). Thermal conductivities of composites with ceramic filler are influenced by filler packing density (Ohashi et al, 2005), particle size and size distribution (Yu et al, 2002) and , surface treatment (Gu et al, 2009) and mixing methods . Models and theories for predicting the thermal conductivity of polymer composites were discussed.…”

Investigation of Lattice Defects in Aluminum Nitride with High Thermal Conductivity by Positron Annihilation Lifetime Measurement

“…Therefore, AlN is expected to the heat dissipative material of high power devices and light emitting diode (LED) etc. Furthermore, AlN filler is now attracting attention in the resin composite material field from the aspect of thermal conductivity [2]. Properties of AlN ceramics are influenced by grain boundaries and lattice defects in AlN crystal.…”