High Thermal Conductivity Film Research Articles

Enhanced thermal conductivity and mechanical property through boron nitride hot string in polyvinylidene fluoride fibers by electrospinning

The electrospun polyvinylidene fluoride (PVDF) based modified boron nitride (m-BN) composite with high thermal conductivity and flexible mechanical property was successfully fabricated by electrospinning method. The uniform dispersion and ordered orientation of m-BN in the m-BN/PVDF composites form a hot string, denoted as a series of thermal conduction fillers, in the direction of the fiber. Hence, the thermal conductivity of the m-BN/PVDF film could reach to 7.29 W m−1K−1 with the addition of 30 wt% m-BN. Besides, the obtained composites also show improved mechanical properties with the tensile strength of 24.06 MPa, low dielectric permittivity of 2.45 and dielectric loss of 0.0242 @ 103 Hz. Therefore, this work provides a new route to prepare the high thermal conductivity films with potential application as flexible power devices.

放熱用絶縁高熱伝導フィルムの開発

放熱用絶縁高熱伝導フィルムの開発

Enhanced thermal and mechanical properties of epoxy composites filled with silver nanowires and nanoparticles

High thermal conductivity films were prepared by blending silver nanowires (AgNws) with epoxy resins. 3-Aminopropyltriethoxysilane (APTES) silane was used to modify the AgNws surface, to produce a high aspect ratio and high thermal conductivity. A thermal interface material with a high thermal conductivity coefficient was used to form a thermal channel in epoxy resins, which possess superior thermal conductivity when the composite contained AgNws higher than 50phr. The phr ratio of AgNws to silver nanoparticles (AgNps) loading was 50:300 when the thermal conductivity coefficient of the composite reached approximately 8W/mK. The composite density ratio of AgNws (50phr) to AgNps (300phr) was 1.512:3.650 (g/cm3), which suggests that the density can be reduced by more than 50% in weight when AgNws, rather than AgNps, were used to prepare thermal interface composites. Furthermore, the adhesion test indicates that the composite containing a lower loading of AgNws exhibits higher adhesive property than that of the composite containing a higher loading of AgNps with a similar thermal conductivity coefficient, thereby resulting in enhanced adhesiveness between devices.

A novel method of hotspot temperature reduction for a 3D stacked CMOS IC chip device fabricated on an ultrathin substrate

A high-performance thermal management method for three-dimensional integrated circuit (IC) integration has been developed for use in conjunction with a three-dimensional (3D) large-scale integration (LSI) technology. By depositing a 10 µm thick high thermal conductivity (HTC) film consisting of 1680 alternating layers of silicon and graphite nano-films directly onto the backside of a Si substrate via an automatic sequencing sputtering method, reduction in the transient hotspot temperature in a thin-substrate CMOS IC chip is achieved. It is shown that this novel HTC film is able to overcome the thermal problems associated with thin substrates and allow the cooling of stacked ICs. In the work described in this paper, we demonstrated the performance of the HTC using a 100 µm thick substrate IC chip consisting of a complementary metal-oxide semiconductor (CMOS) ring oscillator circuit film. Our experimental results, which were confirmed in simulation, reveal a 28% reduction in the hotspot temperature rise owing to the presence of the HTC film. This technology is applicable to future developments in the 3D ultrathin substrate LSI chip stacking technology utilizing through-silicon vias (TSVs) and micro-bumps.

Rapid Thermal Characterization of the High Thermal Conductivity Film Layers by the Film-on Substrate Technique

Lack of an efficient thermal management strategy and system can often lead to overall system failure in advanced microprocessors. This can be avoided by utilization of the high thermal conductivity materials, as heat spreader/sink, in compact packaging systems. The diamondlike dielectric materials, such as diamond, silicon nitride (Si3N4), aluminum nitride (AlN), silicon carbide (SiC), etc., are the likely choices. However, thermal characterization of such high thermal conductivity materials has proven to be challenging due to variations in the fabrication processes and, therefore, their microstructures as well as the practical difficulties in measuring small temperature gradients during the characterization. In this paper, we will report on a novel film on substrate technique that can be used conveniently for repeated measurements of the lateral thermal conductivity of the high thermal conductivity film layers, with thicknesses between 100 and 500μm.

Super-resolution in laser annealing and ablation

This letter reports observation of ablated holes as small as 0.7 μm fabricated by single 25 ns pulses of KrF (λ=248 nm) laser focused onto a 5.6 μm spot. Samples with high thermal conductivity films with respect to that of the substrate (Si/silica, Al/glass) repeatedly showed considerable reduction in the size of the ablated spot (0.7- and 1.2-μm-diam holes, respectively). This letter also presents a likely mechanism of the observed super-resolution and the criteria necessary to achieve super-resolution. Due to the nonoptical origin of this effect it is expected that a tightly focused (<0.5 μm) laser beam can be used to ablate with nanoscale (<100 nm) resolution.