Silicone Gel Thermal Interface Materials for High Heat Dissipation and Thermo-Mechanical Stress Management for Good Reliability Performance

2005 ◽  
Author(s):  
J. C. Matayabas ◽  
Vassou LeBonheur
Keyword(s):  
High Performance ◽  
Heat Dissipation ◽  
High Heat ◽  
Thermal Interface Material ◽  
Market Demand ◽  
Heat Spreader ◽  
Good Reliability ◽  
Theoretical Understanding ◽  
Thermal Interface ◽  
Silicone Gel

The recent trend in microprocessor architecture has been to increase the number of transistors (higher power), shrink processor size (smaller die), and increase clock speeds (higher frequency) in order to meet the market demand for high performance microprocessors. These have resulted in the escalation of power dissipation as well as the heat flux at the silicon die level. The Intel packaging technology development group has been challenged to develop packaging solutions that not only meet the package thermal targets but also the reliability requirements. As a result, an integrated heat spreading (IHS) package was developed, comprising a Cu based heat spreader and a first level thermal interface material (TIM) between the die and the heat spreader. Due to CTE mismatches between its different elements, the IHS package is subjected to high level of thermo-mechanical stresses which lead to severe failures post reliability testing. A significant amount of theoretical understanding of thermal resistance has been developed and applied to the development of TIM formulations, and it was found that the thermo-mechanical properties of the TIM material need to be optimized to mitigate the package reliability stresses. Several material and process solutions have been investigated using fundamental approaches, and, as a result of these efforts, low stress silicone gel TIM’s were developed. This paper provides an overview of the silicone gel TIM technologies investigated at Intel, and the key learnings from the fundamental material and package integration studies.

Thermal Resistance Analysis of Sn-Bi Solder Paste Used as Thermal Interface Material for Power Electronics Applications

2014 ◽  
Vol 136 (1) ◽  
Author(s):  
Rui Zhang ◽  
Jian Cai ◽  
Qian Wang ◽  
Jingwei Li ◽  
Yang Hu ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Power Electronics ◽  
Heat Dissipation ◽  
Laser Flash ◽  
Acoustic Microscopy ◽  
Thermal Interface Material ◽  
Solder Paste ◽  
Good Reliability ◽  
Thermal Interface ◽  
Power Modules

To promote heat dissipation in power electronics, we investigated the thermal conduction performance of Sn-Bi solder paste between two Cu plates. We measured the thermal resistance of Sn-Bi solder paste used as thermal interface material (TIM) by laser flash technique, and a thermal resistance less than 5 mm2 K/W was achieved for the Sn-Bi TIM. The Sn-Bi solder also showed a good reliability in terms of thermal resistance after thermal cycling, indicating that it can be a promising candidate for the TIM used for power electronics applications. In addition, we estimated the contact thermal resistance at the interface between the Sn-Bi solder and the Cu plate with the assistance of scanning acoustic microscopy. The experimental data showed that Sn-Bi solder paste could be a promising adhesive material used to attach power modules especially with a large size on the heat sink.

Maximum Resolution of a Probe-Based, Steady-State Thermal Interface Material Characterization Instrument

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Ronald J. Warzoha ◽  
Andrew N. Smith ◽  
Maurice Harris
Keyword(s):  
Steady State ◽  
Thermal Resistance ◽  
High Performance ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Interfacial Thermal Resistance ◽  
Uniform Heat Flux ◽  
Thermal Probe ◽  
Thermal Interface

Thermal interface materials (TIMs) constitute a critical component for heat dissipation in electronic packaging systems. However, the extent to which a conventional steady-state thermal characterization apparatus can resolve the interfacial thermal resistance across current high-performance interfaces (RT < 1 mm2⋅K/W) is not clear. In this work, we quantify the minimum value of RT that can be measured with this instrument. We find that in order to increase the resolution of the measurement, the thermal resistance through the instrument's reference bars must be minimized relative to RT. This is practically achieved by reducing reference bar length. However, we purport that the minimization of reference bar length is limited by the effects of thermal probe intrusion along the primary measurement pathway. Using numerical simulations, we find that the characteristics of the probes and surrounding filler material can significantly impact the measurement of temperature along each reference bar. Moreover, we find that probes must be spaced 15 diameters apart to maintain a uniform heat flux at the interface, which limits the number of thermal probes that can be used for a given reference bar length. Within practical constraints, the minimum thermal resistance that can be measured with an ideal instrument is found to be 3 mm2⋅K/W. To verify these results, the thermal resistance across an indium heat spring material with an expected thermal contact resistance of ∼1 mm2⋅K/W is experimentally measured and found to differ by more than 100% when compared to manufacturer-reported values.

Prospects for automotive SiP modules applying IC assembly and packaging technology

2019 ◽  
Vol 2019 (1) ◽  
pp. 000006-000012
Author(s):  
Tomohiro Furukawa ◽  
Takahiro Kasuga ◽  
Masato Umehara ◽  
Yuka Tamadate
Keyword(s):  
Flip Chip ◽  
Heat Dissipation ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Interface Material ◽  
Heat Sources ◽  
Heat Spreader ◽  
Thermal Interface ◽  
Passive Components ◽  
Reflow Temperature ◽  
Assembly Technology

Abstract We develop a package that ensures quality complying with AEC-Q 100 Grade 2 which is in-vehicle quality from various flip chip mounting methods and bump sealing technology with underfill resin and mold resin. FC CSP with heat spreader mounted on the product which has started mass production since last year is in the lineup, The heat dissipation can be improved by attaching the heat spreader directly to the chip backside which are heat sources and the Thermal Interface Material (TIM), using our assembly technology of flip chip mounting and molding the periphery while exposing the chip backside. By adjusting the Coefficient of Thermal Expansion (CTE) and thickness of the material, we realize low warpage and low coplanarity at reflow temperature and product use temperature environment and reduce package displacement behavior, we will improve the secondary mountability to the motherboard and provide reliable packages. Furthermore, it can be applied to SiP modules. It is also possible to construct multiple chip modules by mounting multiple ICs or placing low-passive components around them. We will consider heat spreader mounting on multiple ICs that generate heat, and metal coating on the entire SiP module to have a structure that achieves both heat dissipation and electromagnetic shielding as a future idea.

Thermal Contact Resistance of Phase Change and Grease Type Polymeric Materials

2000 ◽  
Author(s):  
Ravi S. Prasher ◽  
Craig Simmons ◽  
Gary Solbrekken
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Phase Change ◽  
High Performance ◽  
Phase Change Materials ◽  
Thermal Contact ◽  
Polymeric Materials ◽  
Thermal Interface Material ◽  
Heat Spreader ◽  
Thermal Grease

Abstract Thermal interface material (TIM) between the die and the heat spreader or between the heat spreader and the heat sink in any electronic package plays a very important role in the thermal management of electronic cooling. Due to increased power and power density high-performance TIMs are sought every day. Phase change materials (PCM) seem to be very good alternative to traditionally used thermal greases because of various reasons. These phase change materials also have the advantage of being reworked easily without damaging the die. Typically these phase change materials are polymer based and are particle laden to enhance their thermal conductivity. The thermal conductivity of these materials is relatively well understood than their contact resistance. Current work focuses on explicitly measuring the contact resistance and the thermal conductivity of a particular phase change TIM and some silicon-based greases. Effect of various parameters, which can affect the contact resistance of theses TIMs and Greases, are also captured. The steady state measurements of the thermal conductivity and the contact resistance was done on an interface tester. In general the work on the contact resistance of fluid-like polymer based TIM, such as thermal grease or phase change polymer has been experimental in the past. A semi-analytical model, which captures the various parameters affecting the contact resistance of two class of materials; the phase change and the thermal grease is also developed in this paper. This model fits very well with the experimental data.

A HIGH THROUGHPUT, LOW COST ASSEMBLY APPROACH FOR LED IMS PACKAGES TO HEAT SINK USING ADVANCED THERMAL INTERFACE MATERIALS

2015 ◽  
Vol 2015 (1) ◽  
pp. 000627-000632 ◽  
Author(s):  
Swapan K. Bhattacharya ◽  
Fei Xie ◽  
Han Wu ◽  
Kelley Hodge ◽  
Keck Pathammavong ◽  
...  
Keyword(s):  
Heat Sink ◽  
High Performance ◽  
High Reliability ◽  
Low Cost ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Cycle Times ◽  
High Adhesion ◽  
Machine Cycle

The objective of this study is to design and fabricate a high reliability LED Insulated Metal Substrate (IMS) package to complex heat sink attachment using an advanced thermal interface material (TIM). The assembly consists of LED IMS parts bonded to a heat spreader/sink using an advanced TIM and a corner bond material to quickly and accurately secure the LEDs in position. The corner bond adhesive is snap cured for fast machine cycle times while the high performance, high adhesion TIM materials cure throughout the rest of the assembly operation. This approach allows high accuracy LED bonding without the need for alignment pins or fasteners to anchor to the IMS. The IMS attached to the heat sink is then electrically interconnected with a thin flex substrate on top of the IMS. This approach is expected to replace the current mechanical fastners and low strength silicone TIM materials and reduce the cycle time and overall placement cost which are key drivers especially for the automotive industry.

Using In situ Capacitance Measurements to Monitor the Stability of Thermal Interface Materials in Complex PCB Assemblies

2010 ◽  
Vol 2010 (1) ◽  
pp. 000450-000457
Author(s):  
Michael Gaynes ◽  
Timothy Chainer ◽  
Edward Yarmchuk ◽  
John Torok ◽  
David Edwards ◽  
...  
Keyword(s):  
Thermal Cycle ◽  
Bond Line ◽  
Thermal Interface Material ◽  
Circuit Board ◽  
Large Area ◽  
Voltage Transformer ◽  
Heat Spreader ◽  
Thermal Interface ◽  
Thermal Solution

A thermal solution for an array of voltage transformer modules which are cooled by a large area, common aluminum heat spreader for a high end server was evaluated using an in situ, capacitive bond line thermal measurement technique. The method measures the capacitance of a non-electrically conducting thermal interface material (TIM) between the electronic module and heat spreader to quantify the TIM bond line effective thickness during assembly and operation. The thermal resistance of the TIM has the same geometric dependence as the inverse of capacitance, therefore, the capacitive technique also provided a monitor of the thermal performance of the interface. This technique was applied to measure the bond line in real time during the assembly of the heat spreader to an array of 37 modules mounted on a printed circuit board. The results showed that the target bond lines were not achieved by application of a constant force alone on the heat spreader, and guided an improved assembly process. The mechanical motion of the TIM was monitored in situ during thermal cycling and found to fluctuate systematically from the hot to cold portions of the thermal cycle, either compressing or stretching the TIM respectively. The capacitive bond line trend showed thermal interface degradation vs. cycle count for several modules which was confirmed by disassembly and visual inspection. Areas of depleted TIM ranged as high as 25% of the module area. Several design and material changes were shown to improve the TIM stability. Power cycling tests were run in parallel to the thermal cycle tests to help relate the results to field performance. The capacitance technique enabled the development and verification of a thermal solution for a complex mechanical system early in the development cycle.

Challenges in Package Cooling of High Performance Servers

2007 ◽  
Author(s):  
Jie Wei
Keyword(s):  
Thermal Conductivity ◽  
Power Dissipation ◽  
High Performance ◽  
Heat Pipes ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
Heat Spreader ◽  
Asymmetric Power ◽  
Heat Spreading ◽  
Silver Composite

Cooling technologies for dealing with high-density and asymmetric power dissipation are discussed, arising from thermal management of high performance server CPU-packages. In this paper, investigation and development of associated technologies are introduced from a viewpoint of industrial application, and attention is focused on heat conduction and removal at the package and heatsink module level. Based on analyses of power dissipation and package cooling characteristics, properties of a new metallic thermal interface material are presented where the Indium-Silver composite was evaluated for integrating the chip and its heat-spreader, effects of heat spreading materials on package thermal performance are investigated including high thermal conductivity diamond composites, and evaluations of enhanced heatsink cooling capability are illustrated where high thermal conductivity devices of heat pipes or vapor chambers were applied for improving heat spreading in the heatsink base.

scholarly journals Recent Advances in Design and Preparation of Polymer-Based Thermal Management Material

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2797 ◽  
Author(s):  
Hongli Zhang ◽  
Tiezhu Shi ◽  
Aijie Ma
Keyword(s):  
Thermal Management ◽  
High Performance ◽  
Heat Dissipation ◽  
Electronic Devices ◽  
High Heat ◽  
Consumer Electronics ◽  
Recent Advances ◽  
Processing Strategies ◽  
Innovative Material ◽  
Processing Properties

The boosting of consumer electronics and 5G technology cause the continuous increment of the power density of electronic devices and lead to inevitable overheating problems, which reduces the operation efficiency and shortens the service life of electronic devices. Therefore, it is the primary task and a prerequisite to explore innovative material for meeting the requirement of high heat dissipation performance. In comparison with traditional thermal management material (e.g., ceramics and metals), the polymer-based thermal management material exhibit excellent mechanical, electrical insulation, chemical resistance and processing properties, and therefore is considered to be the most promising candidate to solve the heat dissipation problem. In this review, we summarized the recent advances of two typical polymer-based thermal management material including thermal-conduction thermal management material and thermal-storage thermal management material. Furtherly, the structural design, processing strategies and typical applications for two polymer-based thermal management materials were discussed. Finally, we proposed the challenges and prospects of the polymer-based thermal management material. This work presents new perspectives to develop advanced processing approaches and construction high-performance polymer-based thermal management material.

scholarly journals RGO-Coated Polyurethane Foam/Segmented Polyurethane Composites as Solid–Solid Phase Change Thermal Interface Material

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3004
Author(s):  
Cong Zhang ◽  
Zhe Shi ◽  
An Li ◽  
Yang-Fei Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
High Performance ◽  
In Situ Polymerization ◽  
Solid Phase ◽  
Thermal Interface Material ◽  
Segmented Polyurethane ◽  
Thermal Interface ◽  
Self Assembling

Thermal interface material (TIM) is crucial for heat transfer from a heat source to a heat sink. A high-performance thermal interface material with solid–solid phase change properties was prepared to improve both thermal conductivity and interfacial wettability by using reduced graphene oxide (rGO)-coated polyurethane (PU) foam as a filler, and segmented polyurethane (SPU) as a matrix. The rGO-coated foam (rGOF) was fabricated by a self-assembling method and the SPU was synthesized by an in situ polymerization method. The pure SPU and rGOF/SPU composite exhibited obvious solid–solid phase change properties with proper phase change temperature, high latent heat, good wettability, and no leakage. It was found that the SPU had better heat transfer performance than the PU without phase change properties in a practical application as a TIM, while the thermal conductivity of the rGOF/SPU composite was 63% higher than that of the pure SPU at an ultra-low rGO content of 0.8 wt.%, showing great potential for thermal management.

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