Impact of Aging on Mechanical Properties of Thermally Conductive Gap Fillers

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Abel Misrak ◽  
Tushar Chauhan ◽  
Pavan Rajmane ◽  
Rabin Bhandari ◽  
Dereje Agonafer
Keyword(s):  
Mechanical Properties ◽  
Sample Preparation ◽  
Thermal Aging ◽  
Coefficient Of Thermal Expansion ◽  
Selection Process ◽  
Thermal Interface Materials ◽  
Dynamic Mechanical Analyzer ◽  
Element Analysis ◽  
Thermally Conductive ◽  
Interface Materials

Abstract Thermal interface materials (TIMs) are an important component in electronic packaging, and there is a concerted effort to understand their reliability when used under various environmental load conditions. Previous researchers have investigated gap fillers and other types of TIMs to understand their performance degradation under loading conditions such as thermal cycling and thermal aging. Most of the study in the literature focuses on studying the changes in thermal properties, and there is a lack of understanding when it comes to studying the mechanical behavior of TIMs. Degradation of mechanical properties is the cause for the loss in thermal performance and is critical during TIM selection process. Moreover, mechanical properties such as modulus and coefficient of thermal expansion (CTE) are critical to assess performance of TIMs using finite element analysis (FEA) and potentially save time and money in the evaluation and selection process. Due to the very soft nature of TIMs, sample preparation is a challenging part of material characterization. In this paper, commercially available TIMs are studied using testing methods such as thermomechanical analyzer (TMA), dynamic mechanical analyzer (DMA), and Fourier infrared spectroscopy (FTIR). These methods are used to characterize the material properties and study the changes in properties due to aging. In this work, the followings are presented: impact of filler content on the mechanical properties, sample preparation method for curable TIM materials with specified thicknesses, and impact of thermal aging on mechanical properties.

Estimation of Effective Thermal and Mechanical Properties of Particulate Thermal Interface Materials (TIMs) by a Random Network Model

2017 ◽  
Author(s):  
Pavan Kumar Vaitheeswaran ◽  
Ganesh Subbarayan
Keyword(s):  
Mechanical Properties ◽  
Network Model ◽  
Thermal Stresses ◽  
Volume Fraction ◽  
Random Network ◽  
Thermal Interface Materials ◽  
Thermal And Mechanical Properties ◽  
Thermal Interface ◽  
Classical Models ◽  
Interface Materials

Particulate thermal interface materials (TIMs) are commonly used to transport heat from chip to heat sink. While high thermal conductance is achieved by large volume loadings of highly conducting particles in a compliant matrix, small volume loadings of stiff particles will ensure reduced thermal stresses in the brittle silicon device. Developing numerical models to estimate effective thermal and mechanical properties of TIM systems would help optimize TIM performance with respect to these conflicting requirements. Classical models, often based on single particle solutions or regular arrangement of particles, are insufficient as real-life TIM systems contain a distriubtion of particles at high volume fractions, where classical models are invalid. In our earlier work, a computationally efficient random network model was developed to estimate the effective thermal conductivity of TIM systems [1,2]. This model is extended in this paper to estimate the effective elastic modulus of TIMs. Realistic microstructures are simulated and analyzed using the proposed method. Factors affecting the modulus (volume fraction and particle size distribution) are also studied.

Thermal and Mechanical Properties of Silicone Thermal Interface Materials With Varying Cross-Link Densities

2005 ◽  
Author(s):  
Arun Gowda ◽  
Annita Zhong ◽  
Sandeep Tonapi ◽  
Kaustubh Nagarkar ◽  
K. Srihari
Keyword(s):  
Mechanical Properties ◽  
Thermal Performance ◽  
Cross Linking ◽  
Thermal Interface Materials ◽  
Material System ◽  
Thermal And Mechanical Properties ◽  
Thermal Impedance ◽  
Operating Life ◽  
Thermal Interface ◽  
Interface Materials

Thermal Interface Materials (TIMs) play a key role in the thermal management of microelectronics by providing a path of low thermal impedance between the heat generating devices and the heat dissipating components (heat spreader/sink). In addition, TIMs need to reliably maintain this low thermal resistance path throughout the operating life of the device. Currently, several different TIM material solutions are employed to dissipate heat away from semiconductor devices. Thermal greases, adhesives, gels, pads, and phase change materials are among these material solutions. Each material system has its own advantages and associated application space. While thermal greases offer excellent thermal performance, their uncured state makes them susceptible to pump-out and other degradation mechanisms. On the other hand, adhesives offer structural support but offer a higher heat resistance path. Gels are designed to provide a level of cross-linking to allow the thermal performance of greases and prevent premature degradation. However, the degree of crosslinking can have a significant effect of the behavior of gels. In this research, TIMs with varying cross-linking densities are studied and their thermal and mechanical properties reported. The base resin systems and fillers were maintained constant, while slight compositional alternations were made to induce different degrees of cross-linking.

scholarly journals Hybrid Composites Based on Polypropylene with Basalt/Hazelnut Shell Fillers: The Influence of Temperature, Thermal Aging, and Water Absorption on Mechanical Properties

Polymers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 18 ◽  
Author(s):  
Anna Kufel ◽  
Stanisław Kuciel
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Water Absorption ◽  
Thermal Aging ◽  
Hybrid Composites ◽  
Coefficient Of Thermal Expansion ◽  
Tensile Modulus ◽  
Charpy Impact ◽  
Creep Tests ◽  
Influence Of Temperature

The aim of the research was to study the effects of adding natural fillers to a polypropylene (PP) matrix on mechanical and physical properties of hybrid composites. The 10%, 15%, and 20% by weight basalt fibers (BF) and ground hazelnut shells (HS) were added to the PP matrix. Composites were produced by making use of an injection molding method. Tensile strength, tensile modulus, strain at break, Charpy impact strength, and the coefficient of thermal expansion were determined. The influence of temperature, thermal aging, and water absorption on mechanical properties was also investigated. In addition, short-time creep tests were carried out. To characterize the morphology and the filler distribution within the matrix, a scanning electron microscope (SEM) was used. The results showed that the addition of the two types of filler enhanced mechanical properties. Furthermore, improvements in thermal stability were monitored. After water absorption, the changes in the tensile properties of the tested composites were moderate. However, thermal aging caused a decrease in tensile strength and tensile modulus.

scholarly journals Ball-Milled Recycled Lead-Graphite Pencils as Highly Stretchable and Low-Cost Thermal-Interface Materials

Polymers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 799 ◽  
Author(s):  
Chun-An Liao ◽  
Yee-Kwan Kwan ◽  
Tien-Chan Chang ◽  
Yiin-Kuen Fuh
Keyword(s):  
Low Cost ◽  
Exfoliated Graphite ◽  
Thermal Interface Materials ◽  
Graphite Nanoplatelets ◽  
Thermal Interface ◽  
Thermally Conductive ◽  
Highly Stretchable ◽  
Exfoliated Graphite Nanoplatelets ◽  
Interface Materials ◽  
Thermal Conductivities

A simple and sustainable production of nanoplatelet graphite at low cost is presented using carbon-based materials, including the recycled lead-graphite pencils. In this work, exfoliated graphite nanoplatelets (EGNs), ball-milled exfoliated graphite nanoplatelets (BMEGNs) and recycled lead-graphite pencils (recycled 2B), as well as thermally cured polydimethylsiloxane (PDMS), are used to fabricate highly stretchable thermal-interface materials (TIMs) with good thermally conductive and mechanically robust properties. Several characterization techniques including scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) showed that recycled nanoplatelet graphite with lateral size of tens of micrometers can be reliably produced. Experimentally, the thermal conductivity was measured for EGNs, BMEGNs and recycled 2B fillers with/without the effect of ball milling. The in-plane thermal conductivities of 12.97 W/mK (EGN), 13.53 W/mK (recycled 2B) and 14.56 W/mK (BMEGN) and through-plane thermal conductivities of 0.76 W/mK (EGN), 0.84 W/mK (recycled 2B) and 0.95 W/mK (BMEGN) were experimentally measured. Anisotropies were calculated as 15.31, 15.98 and 16.95 for EGN, recycled 2B and BMEGN, respectively. In addition, the mechanical robustness of the developed TIMs is such that they are capable of repeatedly bending at 180 degrees with outstanding flexibility, including the low-cost renewable material of recycled lead-graphite pencils. For heat dissipating application in high-power electronics, the TIMs of recycled 2B are capable of effectively reducing temperatures to approximately 6.2 °C as favorably compared with thermal grease alone.

Sign in / Sign up

Export Citation Format

Share Document