Electrospinning Equipment: Enhancing Epoxy Molding Compounds' Thermal Conductivity with SiO₂-Embedded Carbon Nanofibers

With the rapid development of artificial intelligence, the Internet of Things, and high - performance computing technologies, the performance requirements for semiconductor chips are constantly increasing. However, the heat dissipation problem caused by the miniaturization and high integration of chips has become a key bottleneck restricting the development of high - performance semiconductors. Recently, a study published in Macromolecular Research proposed an innovative solution: by adding silica - embedded carbon nanofibers (SiO₂/eCNFs), the thermal conductivity and mechanical properties of epoxy molding compounds (EMCs) were significantly enhanced, opening up a new path for the thermal management of semiconductor packaging.

I. Heat Dissipation - The "Stumbling Block" in Semiconductor Development

As the integration level of semiconductors increases, the heat generation of chips has increased dramatically, leading to many performance and reliability issues, such as cracks at the internal input/output terminals of the chip. Currently, although there are various heat dissipation methods, such as microfluidic cooling systems, the application of phase change materials, the use of graphene - based heat sinks, and the embedding of cooling channels in the chip substrate, they all have limitations. For example, microfluidic cooling systems have complex structures and high costs.

Epoxy molding compound (EMC) is a commonly used material for semiconductor packaging. It is composed of epoxy resin, fillers, and curing agents. The fillers account for a large proportion and have a significant impact on the performance. Silica (SiO₂) is a commonly used filler. Although it has a low cost and good performance, with the increasing performance requirements of semiconductors, it is difficult to meet the heat dissipation requirements in terms of thermal performance. Therefore, it is urgent to find a way to improve the thermal conductivity of EMC.

II. New Additive Boosts EMC Performance

This article focuses on the new additive of SiO₂ - embedded carbon nanofibers (SiO₂/eCNFs), aiming to improve the heat dissipation and mechanical properties of EMC for semiconductor packaging. The researchers prepared three sizes of SiO₂ nanoparticles and added them to the precursor solution of polyacrylonitrile (PAN) nanofibers. The electrospinning machine was then employed to carry out the electrospinning process. Through electrospinning and carbonization, SiO₂ nanoparticle - embedded PAN nanofibers were successfully converted into SiO₂/eCNFs. Different concentrations (0.1 - 1.0 wt%) of SiO₂/eCNFs were mixed with EMC to study their effects. The results showed that when 0.4 wt% of 500SiO₂/eCNFs was added to EMC, the thermal conductivity increased by 67% and the impact strength increased by 43%. Observations with an infrared camera found that the surface temperature of the chip packaged with this material rose faster, indicating that it has great potential in improving the heat dissipation performance of EMC and is expected to become a key additive for next - generation high - performance semiconductor packaging.

III. Main Research Content and Methods

The research team first prepared three different sizes (100 nm, 300 nm, and 500 nm) of SiO₂ nanoparticles by the Stöber method and uniformly dispersed them in the polyacrylonitrile (PAN) precursor solution. Subsequently, the electrospinning device was used to spin PAN and SiO₂ nanoparticles into nanofibers. And then carbonized at high temperatures. Finally, SiO₂/eCNFs were prepared (Figure 1). This process not only retained the one - dimensional structure of carbon nanofibers but also successfully embedded SiO₂ nanoparticles, laying the foundation for subsequent thermal management applications.

Next, the researchers added the prepared SiO₂/eCNFs to EMC at different concentrations (0.1 wt% to 1.0 wt%) and systematically evaluated its thermal and mechanical properties. The experimental results showed that when the concentration of SiO₂/eCNFs was 0.4 wt%, the thermal conductivity and impact strength of EMC reached the best values (Figure 2). This discovery indicates that an appropriate amount of SiO₂/eCNFs can significantly improve the performance of EMC, while an excessively high concentration will lead to the aggregation of fillers and instead reduce the thermal conductivity.

To deeply understand the mechanism of SiO₂/eCNFs in EMC, the researchers characterized the microstructure of the material through scanning electron microscopy (SEM) and optical microscopy (OM) (Figure 3). The results showed that SiO₂/eCNFs could successfully embed between the fillers of EMC, forming additional heat conduction channels, and at the same time, they exhibited good interfacial adhesion with the epoxy resin matrix.

In addition, the research team also actually tested the thermal performance of the packaged chips using an infrared camera. In the experiment, chips packaged with SiO₂/eCNFs - EMC and traditional EMC were placed on a 70°C heating plate, and the changes in their surface temperatures were observed (Figure 4). The results showed that the surface temperature of the chips packaged with SiO₂/eCNFs - EMC rose faster and the temperature distribution was more uniform, further confirming its advantages in thermal management.

IV. Innovation Points and Conclusions

The innovation of this study lies in combining one - dimensional carbon nanofibers with zero - dimensional SiO₂ nanoparticles to form a new type of composite additive. This structure not only fully utilizes the high thermal conductivity and one - dimensional advantages of carbon nanofibers but also optimizes the compatibility with EMC fillers through the embedded SiO₂ nanoparticles, thus significantly enhancing the thermal conductivity and mechanical properties of EMC. During the preparation process, the electrospinning machine played a crucial role in fabricating the SiO₂/eCNFs. In addition, through experimental verification, this new EMC additive has demonstrated excellent thermal management performance in actual chip packaging, providing a highly promising solution for the field of high - performance semiconductor packaging.

Electrospinning Nanofibers Article Source: 

https://doi.org/10.1007/s13233-024-00317-y