scholarly journals Development of polyvinyl alcohol-based carbon nano fiber sheet for thermal interface material

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiangling Xiong ◽  
Siran Chen ◽  
Yongbum Choi ◽  
Kazuhiro Matsugi

AbstractPolyvinyl alcohol (PVA)-based carbon nanofiber (CNF) sheets are fabricated as an innovative thermal interface material (TIM), which is a potential substitute for traditional TIMs. Five types of PVA-based CNF sheets were fabricated at different mass ratios of PVA:vapor-grown carbon fiber (VGCF) (1:0.100, 1:0.070, 1:0.050, 1:0.030, 1:0.025). The thickness of the PVA-based CNF sheets was 30–50 µm, which was controlled by the amount of VGCF. The microstructure of the CNF sheets indicated that VGCFs were arranged in random directions inside the sheet, and PVA was formed as a membrane between two VGCFs. However, many pores were found to exist between the VGCFs. The porosity of the PVA-based CNF sheets decreased from 25 to 13% upon decreasing the mass ratio of VGCF from 43.38 to 16.13%. The density and Shore hardness of all CNF sheets were 1.03–1.15 × 106 g m−3 and 82.4–85.0 HS, respectively. The highest thermal conductivity, measured as the mass ratio of PVA:VGCF, was achieved at 1:0.05, with the in-plane thermal conductivity of the fabricated sheet being 14.3 W m−1 k−1.

2021 ◽  
pp. 002199832110595
Author(s):  
Weontae Oh ◽  
Jong-Seong Bae ◽  
Hyoung-Seok Moon

The microstructural change of graphite was studied after ultrasonic treatment of the graphite. When the graphite solution was treated with varying ultrasonic power and time, the microstructure changed gradually, and accordingly, the thermal conductivity characteristics of the composite containing the as-treated graphite was also different with each other. Thermal conductivity showed the best result in the silicone composite containing graphite prepared under the optimum condition of ultrasonic treatment, and the thermal conductivity of the composite improved proportionally along with the particle size of graphite. When the silicone composite was prepared by using a mixture of inorganic oxides and graphite rather than graphite alone, the thermal conductivity of the silicone composite was further increased. A silicone composite containing graphite was used for LED (light emitting diode) lighting system as a thermal interface material (TIM), and the temperature elevation due to heat generated, while the lighting was actually operated, was analyzed.


2018 ◽  
Vol 7 (4.33) ◽  
pp. 530
Author(s):  
Mazlan Mohamed ◽  
Mohd Nazri Omar ◽  
Mohamad Shaiful Ashrul Ishak ◽  
Rozyanty Rahman ◽  
Zaiazmin Y.N ◽  
...  

Epoxy mixed with others filler for thermal interface material (TIM) had been well conducted and developed. There are problem occurs when previous material were used as matrix material likes epoxy that has non-uniform thickness of thermal interface material produce, time taken for solidification and others. Thermal pad or thermal interface material using graphene as main material to overcome the existing problem and at the same time to increase thermal conductivity and thermal contact resistance. Three types of composite graphene were used for thermal interface material in this research. The sample that contain 10 wt. %, 20 wt. % and 30 wt. % of graphene was used with different contain of graphene oxide (GO).  The thermal conductivity of thermal interface material is both measured and it was found that the increase of amount of graphene used will increase the thermal conductivity of thermal interface material. The highest thermal conductivity is 12.8 W/ (mK) with 30 w. % graphene. The comparison between the present thermal interface material and other thermal interface material show that this present graphene-epoxy is an excellent thermal interface material in increasing thermal conductivity.  


Author(s):  
David Shaddock ◽  
Stanton Weaver ◽  
Ioannis Chasiotis ◽  
Binoy Shah ◽  
Dalong Zhong

The power density requirements continue to increase and the ability of thermal interface materials has not kept pace. Increasing effective thermal conductivity and reducing bondline thickness reduce thermal resistance. High thermal conductivity materials, such as solders, have been used as thermal interface materials. However, there is a limit to minimum bondline thickness in reducing resistance due to increased fatigue stress. A compliant thermal interface material is proposed that allows for thin solder bondlines using a compliant structure within the bondline to achieve thermal resistance <0.01 cm2C/W. The structure uses an array of nanosprings sandwiched between two plates of materials to match thermal expansion of their respective interface materials (ex. silicon and copper). Thin solder bondlines between these mating surfaces and high thermal conductivity of the nanospring layer results in thermal resistance of 0.01 cm2C/W. The compliance of the nanospring layer is two orders of magnitude more compliant than the solder layers so thermal stresses are carried by the nanosprings rather than the solder layers. The fabrication process and performance testing performed on the material is presented.


2019 ◽  
Vol 2019 (1) ◽  
pp. 000312-000315
Author(s):  
Maciej Patelka ◽  
Sho Ikeda ◽  
Koji Sasaki ◽  
Hiroki Myodo ◽  
Nortisuka Mizumura

Abstract High power semiconductor applications require a Thermal Interface Die Attach Material with high thermal conductivity to efficiently release the heat generated from these devices. Current Thermal Interface Material solutions such as thermal grease, thermal pads and silicones have been industry standards, however may fall short in performance for high temperature or high-power applications. This presentation will focus on development of a cutting-edge Die Attach Solution for Thermal Interface Management, focusing on Fusion Type epoxy-based Ag adhesive with an extremally low Storage Modulus and the Thermal Conductivity reaching up to 30W/mK, and also Very Low Modulus, Low-Temperature Pressureless Sintered Silver Die Attach with the Thermal Conductivity of 70W/mK.


2019 ◽  
Vol 32 (5) ◽  
pp. 506-523 ◽  
Author(s):  
Sagar Kumar Nayak ◽  
Smita Mohanty ◽  
Sanjay K Nayak

In this work, a facile two-step method for the synthesis of highly thermal conductive expanded graphite (EG) was proposed. A binary component system of ammonium persulfate and concentrated sulfuric acid was prepared for the synthesis of EG from natural graphite flakes in which the former one acted as an oxidizing agent and the latter one used as an intercalating agent. Further, the silane functionalization of EG (mEG) was purposefully completed, as confirmed from the X-ray diffraction and Fourier transform infrared spectroscopy analysis. Epoxy-based thermal interface materials (TIMs) were fabricated with reinforcing EG and mEG by stir-casting method at different filler fraction. The guarded heat flow meter method indicated that the enhancement in thermal conductivity (TC) was 12.12-fold at 10 wt% loading of mEG (mEG10-Ep) than neat epoxy. The binding strength of mEG10-Ep composite tuned to 6.18 ± 0.8 MPa and determined by a single lap shear test, which confirms better reinforcing effect of silane functionalized EG than neat EG counterpart. The same was also corroborated from porosity evaluation of the composite system. At 50% weight loss in nitrogen atmosphere, thermogravimetric analysis revealed that the composite was stable up to 430°C. Dynamic mechanical analysis was engaged to estimate the glass transition temperature ( T g) of the epoxy composite system, which validates its prospective application as preferred TIMs in the electroactive device. The electrical conductivity of composite was deteriorated due to the encapsulation of EG with nonconductive silane functional groups. The uniform dispersion was achieved by mEG-filled composite as compared to its EG counterpart, which was visualized from fracture surface through scanning electron microscopy.


2018 ◽  
Vol 6 (36) ◽  
pp. 17540-17547 ◽  
Author(s):  
Zhilin Tian ◽  
Jiajia Sun ◽  
Shaogang Wang ◽  
Xiaoliang Zeng ◽  
Shuang Zhou ◽  
...  

A high thermal conductivity boron nitride based thermal interface material was developed by a foam-templated method.


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