Measurement of High-Performance Thermal Interfaces Using a Reduced Scale Steady-State Tester and Infrared Microscopy

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Andrew N. Smith ◽  
Nicholas R. Jankowski ◽  
Lauren M. Boteler
Keyword(s):  
Steady State ◽  
High Performance ◽  
Thermal Interface Materials ◽  
Interfacial Resistance ◽  
Heat Meter ◽  
Thermal Interface ◽  
Order Of Magnitude ◽  
Interface Materials ◽  
Reduced Scale ◽  
Magnitude Improvement

Thermal interface materials (TIMs) have reached values approaching the measurement uncertainty of standard ASTM D5470 based testers of approximately ±1 × 10−6 m2 K/W. This paper presents a miniature ASTM-type steady-state tester that was developed to address the resolution limits of standard testers by reducing the heat meter bar thickness and using infrared (IR) thermography to measure the temperature gradient along the heat meter bar. Thermal interfacial resistance measurements on the order of 1 × 10−6 m2 K/W with an order of magnitude improvement in the uncertainty of ±1 × 10−7 m2 K/W are demonstrated. These measurements were made on several TIMs with a thermal resistance as low as 1.14 × 10−6 m2 K/W.

Interfacial Resistance Measurement of High Performance Thermal Interface Materials

2013 ◽  
Author(s):  
Andrew N. Smith ◽  
Nicholas Jankowski ◽  
Lauren Boteler ◽  
Christopher Meyer
Keyword(s):  
Temperature Difference ◽  
High Performance ◽  
Thermal Interface Materials ◽  
Interfacial Resistance ◽  
Resolution Limit ◽  
Heat Meter ◽  
Thermal Interface ◽  
Ir Camera ◽  
Heater Element ◽  
Interface Materials

Advancements in thermal interface materials have reached the resolution limit of typical ASTM D5470 based testers, which is around ±1×10−6 m2K/W. As the interfacial resistance is reduced, the temperature difference at the interface decreases and ultimately becomes difficult to measure. Standard ASTM testers utilize precise temperature sensors and knowledge of the thermal conductivity of the heat meter bar to resolve the temperature difference at the interface. It is difficult to resolve interface resistances on the order of 1×10−6 m2K/W, even when precision RTDs with a resolution of ±0.001°C are utilized, as the location uncertainty of the sensor can become important. Increasing the temperature difference across the interface is necessary for further improvement in the resolution. This work presents a miniature ASTM type tester that was developed to address the resolution limits of standard testers by reducing the heat meter bar thickness, using a chip resistor as the heater element, and using an IR camera to measure the temperature gradient along the meter bar. Reducing the length of the heat meter bars reduces the overall resistance, and increases the resistance of the interface relative to that of the meter bars. Because of the reduced size scale of the miniature tester, measurement of the temperature profile using the typical ASTM approach of embedding temperature probes along the length of the meter bar was not feasible but instead was achieved using a relatively inexpensive uncooled long wavelength infrared camera with a microscope attachment in order to focus down to ∼100 microns. Although the IR camera increases the uncertainty of the measured temperatures, this method is shown to measure a thermal interfacial resistance of 1.45×10−6 m2K/W with an uncertainty of ±1.1×10−7 m2K/W, where the sample interface was a 2 mil AuSn preform soldered interface.

Characterization of Metallically Bonded Carbon Nanotube-Based Thermal Interface Materials Using a High Accuracy 1D Steady-State Technique

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Joseph R. Wasniewski ◽  
David H. Altman ◽  
Stephen L. Hodson ◽  
Timothy S. Fisher ◽  
Anuradha Bulusu ◽  
...  
Keyword(s):  
Steady State ◽  
High Performance ◽  
Applied Pressure ◽  
Test Facility ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Thermal Interface Resistance ◽  
Vertically Aligned ◽  
Performance Results ◽  
Interface Materials

The next generation of thermal interface materials (TIMs) are currently being developed to meet the increasing demands of high-powered semiconductor devices. In particular, a variety of nanostructured materials, such as carbon nanotubes (CNTs), are interesting due to their ability to provide low resistance heat transport from device-to-spreader and compliance between materials with dissimilar coefficients of thermal expansion (CTEs), but few application-ready configurations have been produced and tested. Recently, we have undertaken major efforts to develop functional nanothermal interface materials (nTIMs) based on short, vertically aligned CNTs grown on both sides of a thin interposer foil and interfaced with substrate materials via metallic bonding. A high-precision 1D steady-state test facility has been utilized to measure the performance of nTIM samples, and more importantly, to correlate performance to the controllable parameters. In this paper, we describe our material structures and the myriad permutations of parameters that have been investigated in their design. We report these nTIM thermal performance results, which include a best to-date thermal interface resistance measurement of 3.5 mm2 K/W, independent of applied pressure. This value is significantly better than a variety of commercially available, high-performance thermal pads and greases we tested, and compares favorably with the best results reported for CNT-based materials in an application-representative setting.

Characterization of Metallically Bonded Carbon Nanotube-Based Thermal Interface Materials Using a High Accuracy 1D Steady-State Technique

2011 ◽  
Author(s):  
Joseph R. Wasniewski ◽  
David H. Altman ◽  
Stephen L. Hodson ◽  
Timothy S. Fisher ◽  
Anuradha Bulusu ◽  
...  
Keyword(s):  
Steady State ◽  
High Performance ◽  
Applied Pressure ◽  
Test Facility ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Thermal Interface Resistance ◽  
Vertically Aligned ◽  
Performance Results ◽  
Interface Materials

The next generation of Thermal Interface Materials (TIMs) are currently being developed to meet the increasing demands of high-powered semiconductor devices. In particular, a variety of nanostructured materials, such as carbon nanotubes (CNTs), are interesting due to their ability to provide low resistance heat transport from device to spreader and compliance between materials with dissimilar coefficients of thermal expansion (CTEs). As a result, nano-Thermal Interface Materials (nTIMs) have been conceived and studied in recent years, but few application-ready configurations have been produced and tested. Over the past year, we have undertaken major efforts to develop functional nTIMs based on short, vertically-aligned CNTs grown on both sides of a thin interposer foil and interfaced with substrate materials via metallic bonding. A high-precision 1-D steady-state test facility has been utilized to measure the performance of nTIM samples, and more importantly, to correlate performance to the controllable parameters. Nearly 200 samples have been tested utilizing myriad permutations of such parameters, contributing to a deeper understanding and optimization of CNT growth characteristics and application processing conditions. In addition, we have catalogued thermal resistance results from a variety of commercially-available, high-performance thermal pads and greases. In this paper, we describe our material structures and the parameters that have been investigated in their design. We report these nTIM thermal performance results, which include a best to-date thermal interface resistance measurement of 3.5 mm2-K/W, independent of applied pressure. This value is significantly better than all commercial materials we tested and compares favorably with the best results reported for CNT-based nTIMs in an application-representative setting.

scholarly journals Graphene-Based Thermal Interface Materials: An Application-Oriented Perspective on Architecture Design

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1201 ◽  
Author(s):  
Le Lv ◽  
Wen Dai ◽  
Aijun Li ◽  
Cheng-Te Lin
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Electronic Devices ◽  
Point Of View ◽  
Future Research ◽  
Thermal Interface Materials ◽  
Research Directions ◽  
Thermal Interface ◽  
Future Research Directions ◽  
Interface Materials

With the increasing power density of electrical and electronic devices, there has been an urgent demand for the development of thermal interface materials (TIMs) with high through-plane thermal conductivity for handling the issue of thermal management. Graphene exhibited significant potential for the development of TIMs, due to its ultra-high intrinsic thermal conductivity. In this perspective, we introduce three state-of-the-art graphene-based TIMs, including dispersed graphene/polymers, graphene framework/polymers and inorganic graphene-based monoliths. The advantages and limitations of them were discussed from an application point of view. In addition, possible strategies and future research directions in the development of high-performance graphene-based TIMs are also discussed.

Thermomechanical Degradation of Thermal Interface Materials: Accelerated Test Development and Reliability Analysis

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Hayden Carlton ◽  
Dustin Pense ◽  
David Huitink
Keyword(s):  
Thermal Performance ◽  
Structural Integrity ◽  
Void Formation ◽  
Conductivity Measurement ◽  
Cyclic Stress ◽  
Thermal Interface Materials ◽  
Interfacial Resistance ◽  
Thermal Interface ◽  
Mechanical Cycling ◽  
Interface Materials

Abstract Due to the inherently low adhesive strength and structural integrity of polymer thermal interface materials (TIMs), they present a likely point of failure when succumbed to thermomechanical stresses in electronics packaging. Herein, we present a methodology to quantify TIM degradation through an accelerated and repeatable mechanical cycling technique. The testing apparatus incorporated a steady-state thermal conductivity measurement system, consistent with ASTM 5470-06, with added displacement actuation and force sensing to provide controlled cyclic loading between −20 N and 20 N. Additionally, a novel optical technique was utilized to observe void formation, pump-out, and dry-out behavior during cycling, in order to correlate the thermal performance with physical behaviors of different TIMs under cyclic stress. Of the two different pastes analyzed, cyclic testing was found to degrade the thermal performance of the less viscous TIM by increasing its interfacial resistance. Optical qualitative measurements revealed the breakdown of the TIM structure at the interface, which indicated the formation of voids due to TIM degradation. Applying this testing method for future TIM development could help in optimizing TIM structure for particular package applications.

Thermo-Mechanical Degradation of Thermal Interface Materials: Accelerated Test Development and Reliability Analysis

2019 ◽  
Author(s):  
Dustin Pense ◽  
Hayden Carlton ◽  
David Huitink
Keyword(s):  
Thermal Performance ◽  
Structural Integrity ◽  
Mechanical Degradation ◽  
Thermal Interface Materials ◽  
Interfacial Resistance ◽  
Thermal Reliability ◽  
Thermal Interface ◽  
Static Test ◽  
Mechanical Cycling ◽  
Interface Materials

Abstract Thermal interface materials (TIMs) comprise an important role in the thermal management of a myriad of electronic devices, and their ability to ensure both enhanced thermal conductance and reliable adhesion at thermal interfaces is paramount to the reliability of electronics packaging. Like most aspects of a typical electronics package, on/off cycles undergone during a device’s operation induce thermo-mechanical stresses that can negatively affect the integrity of the package. Due to the inherently low adhesive strength and structural integrity of polymer TIMs, they present a likely point of failure when succumbed to these interfacial stresses. Methods for quantifying TIM degradation during mechanical cycling have been quite infrequent in literature; an accelerated and repeatable method for measuring the thermal reliability of TIMs would prove to be beneficial. Herein, we present a methodology to quantify the thermal reliability of TIMs during mechanical cycling using a custom-built steady-state thermal conductivity tester. Additionally, an optical technique was utilized to observe void formation, pump-out, and dry-out behavior during cycling, in order to correlate the thermal performance with physical behaviors of the TIM under cyclic stress. After an initial long-term static test, cyclic testing was found to degrade the thermal performance of the TIM through increasing its interfacial resistance. Optical qualitative measurements revealed the breakdown of the TIM structure at the interface, which indicated the formation of voids due to TIM degradation. Applying this testing method for future TIM development could help in optimizing TIM structure for particular package applications.

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