Online proceedings - EDA Publishing Association

More documents

Recommendations

Info

RA (m 2 K/W) 0.0008 0.0007 0.0006 0.0005 0.0004 0.0003 0.0002 0.0001 0 C2 A3 C1 B3 D2 A1 B1 0 0.5 1 1.5 2 2.5 3 Pressure @ 50% Strain (MPa) D1 F3 7-9 October 2009, Leuven, Belgium measurements will be required. Future work will also involve validating the simultaneous thermal-mechanical numerical model developed by Kempers et al. [6] with this data. Additionally, characterization the thermal contact resistance of these MMT-TIMs as they deform is essential to understating their performance and for the design of optimum MMT-TIMs for a given application. Present work revolves around understanding the relationship between electrical and thermal contact resistance for these deformable metal structures in order to develop a simple electrical measurement to estimate the thermal contact resistance of MMT-TIMs. ACKNOWLEDGMENTS This work was supported by IDA Ireland. Special thanks to Paul Ahern of Alcatel-Lucent for the SEM imaging. Fig. 9: Variation of specific thermal resistance with pressure at 50% strain for each MMT-TIM resistances of the bulk MMT-TIM are extremely small compared to the resistance at the contact surfaces. For these MMT-TIMs, it has been proposed that a relatively straightforward electrical resistance measurement be employed to characterize the thermal contact resistance [6,7]. Work is presently being carried out in order to characterize the relationship between thermal and electrical contact resistance of deformable metal structures for this purpose. V. CONCLUSIONS & FUTURE OUTLOOK Several different hollow conical MMT-TIM structures were characterized experimentally. The results explore the effect of various geometrical parameters such as metal thickness, feature height, size, density and shape on both the mechanical and thermal response of the MMT-TIM. Overall, these parameters can exhibit a definite influence both the thermal and mechanical response of the TIM. Generally speaking, MMT-TIMs with thicker metal plating (foil thickness) exhibit a stiffer mechanical response and a slightly higher effective thermal conductivity. Additionally, stiffer structures and MMT-TIMs with high density feature arrays can exhibit higher effective thermal conductivities but also higher thermal resistances due to lower compressibility in the structure. The best overall TIM performance was achieved through a trade-off between effective thermal conductivity and mechanical compliance. This was achieved with sample “D2” where a dense array of conical features formed an interface of multiple, redundant, thermal contacts. Due to the thin metal plating, the features plastically deform relatively easily providing good compliance and a large interfacial contact area. Thicker metal plating does further reduce thermal resistance of the MMT-TIM, but only at the price of significantly higher assembly pressures. The present work represents an initial exploration into the effects of various MMT-TIM geometries on the mechanical and thermal properties. Although some performance trends were demonstrated, the tested structures are far from optimal. Additional experimental structures and REFERENCES [1] Liu, J., Michel, B., Rencz, M., Tantolin, C, Sarno, C., Miessner, R., Schuett, K-V., Tang, X., Demoustier, S. & Ziaei, A., “Recent Progress of Thermal Interface Material Research—An Overview”, Proceedings of the 14 th Workshop on Thermal Issues in ICs and Systems (THERMINIC), Rome, Italy, September 24-26, 2008 [2] Smith B., Brunschwiler, T., & Michel, B. “Comparison of transient and static test methods for chip-to-sink thermal interface characterization”. Microelectron. J., doi:10.1016/j.mejo.2008.06.079 (2008). [3] Linderman, R., Brunschwiler, T., Smith B., and Michel, B. “High performance thermal interface technology overview”. Proceedings of the 13 th Workshop on Thermal Issues in ICs and Systems (THERMINIC), pp. 129-134 (2007). [4] Ziaei, A. & Demoustier, S., “NANOPACK – Nano Packaging Technology for Interconnect and Heat Dissipation”. Proceedings of the 14 th Workshop on Thermal Issues in ICs and Systems (THERMINIC), Rome, Italy, September 24-26, 2008. [5] Liu, J., Michel, B., Rencz, M., Tantolin, C., Sarno, C., Miessner, R., Schuett, K. V., Tang, X., Demoustier, S. & Ziaei, A. “Recent Progress of Thermal Interface Material Research – An Overview”. Proceedings of the 14 th Workshop on Thermal Issues in ICs and Systems (THERMINIC), Rome, Italy, September 24-26, 2008. [6] Kempers, R., Frizzell, R., Lyons, A. & Robinson, A.J., “Development of a Metal Micro-Textured Thermal Interface Material”, ASME InterPACK Conference, IPACK2009-89366, San Francisco, July 8-12, 2009 [7] Kempers, R., Kolodner, P., Lyons, A. & Robinson, A.J. “A High- Precision Apparatus for the Characterization of Thermal Interface Materials” Accepted to Review of Scientific Instruments, (2009). [8] Teertstra, P. “Thermal Conductivity and Contact Resistance Measurements for Adhesives”. Proceedings of ASME InterPACK 2007, Vancouver, BC, July 8-12, 2007. [9] Madhusudana, C.V., Thermal Contact Conductance, Springer-Verlag, New York, (1996). [10] Braunovic, M., Konchits, V.V. &Myshkin, N.K., Electrical Contacts: Fundamentsl, Aplications and Technology, CRC Press, (2007). ©EDA Publishing/THERMINIC 2009 215 ISBN: 978-2-35500-010-2
7-9 October 2009, Leuven, Belgium Carbon Nanotube Enhanced Thermally Conductive Phase Change Material For Heat Dissipation Xinhe Tang, Ernst Hammel and Werner Reiter Electrovac AG Aufeldgasse 37-39 3400 Klosterneuburg, Austria Tel: 0043-2243-450405, Fax: 0043-2243-450315, tan@electrovac.com , www.electrovac.com ABSTRACT Carbon nanotube enhanced thermally conductive phase change material for heat dissipation has been studied in the present paper. It was indicated that the thermal resistance was greatly reduced by incorporating multi-walled carbon nanotubes into the organic matrix. The uniform distribution of carbon nanotubes has been realized by optimizing the dispersion parameters like temperature, shear strength, rolling speed and gap of rollers. New phase change materials have been developed and the thermal performance has been evaluated. The further work relating to physical and mechanical properties and application in heat dissipation is being undertaken. Key words: carbon nanotubes, nanofiller enhanced phase change material, thermal performance, thermal resistance I. INTRODUCTION An organic phase change material (PCM) shows thermal storage capacity due to its latent heat of transformation, but its application in thermal management is limited owing to its low thermal conductivity. It is expected that embedding a thermally conductive nanofiller in the PCM matrix can either increase the thermal conductivity of the composite or decrease the thermal resistance, and therefore reduce the junction temperature of the components. Carbon nanotubes (CNTs) possess high thermal conductivity in the axis direction. An individual multi-walled carbon nanotube (MWCNT) can be as high as 3000 W/mK in thermal conductivity [1]. The CNTs with their outstanding conductivity have a great potential to be employed in PCM for heat dissipation. It is believed that the high inherent thermal conductivity of CNTs significantly enhances the thermal conductivity of the PCM. It was indicated that the thermal grease made from carbon nanofibers (CNF) showed low thermal resistance in the previous work [2-3]. It has been reported that CNT arrays lead to a minimum thermal resistance of 19.8 Kmm 2 /W, while the combination of the CNT arrays with phase change material results in much lower resistance of 5.2 Kmm 2 /W [4]. The dispersion and the formation of a network of CNTs in the matrix, the loading grade of the fillers, the manufacture process and even the properties of the matrix itself exert an important influence on the thermal performance of the PCM. The objective of this work is to develop nanofiller enhanced phase change material by finding out desirable compositions where CNTs and matrix may well be incorporated, and by optimizing dispersing parameters to generate minimum thermal barriers between nanofillers and matrix and to realize a maximum thermal conductivity of the phase change material. In the present work following activities have been involved in developing CNTs enhanced PCM: • Selection of PCM matrices and filler materials; • Pre-treatment of carbon nanotubes; • Optimization of dispersion parameters; • Optimization of loading grade of CNTs; • Evaluation of CNTs distribution in PCM; • Measurment of the thermal resistance of the PCM; • Comparison of the enhancement over the matrix; II. EXPERIMENTAL 1. Selection of carbon nanofibers as filler It has been reported that the thermal grease made from heattreated carbon nanofibers showed lower thermal resistance than any other non-treated CNF and CNT[2]. A multi-walled carbon nanotube was treated at high temperature and used as the filler to enhance the thermal performance. Fig. 1 shows the SEM morphology of this filler material. As many nanoparticles, the carbon nanotubes are also strongly agglomerated, which shows the difficulty to be well dispersed into the organic matrix. Fig. 1: SEM morphology of multi-walled carbon nanotube 2. Selection of organic phase change material The following properties have been taken into account to select organic PCM: ©EDA Publishing/THERMINIC 2009 216 ISBN: 978-2-35500-010-2
Page 1 and 2:
International Workshop on THERMal I
Page 3 and 4:
7-9 October 2009, Leuven, Belgium
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Poster session: Introduction* 7-9 O
Page 11 and 12:
7-9 October 7-9 October 2009, 2009,
Page 13 and 14:
7-9 October 2009, Leuven, Belgium T
Page 15 and 16:
7-9 October 2009, Leuven, Belgium u
Page 17 and 18:
7-9 October 2009, Leuven, Belgium p
Page 19 and 20:
7-9 October 2009, Leuven, Belgium E
Page 21 and 22:
x −1 V(x) = , f(y) = x + 1 y + 1
Page 23 and 24:
of 75 o C for fair comparison. Only
Page 25 and 26:
II. GCS DESIGN AND FIELD TEST 7-9 O
Page 27 and 28:
7-9 October 2009, Leuven, Belgium a
Page 29 and 30:
External Nodes (ne) European projec
Page 31 and 32:
G 2 (resp. C 2 , F 2 ) and G 2e (re
Page 33 and 34:
TABLE I MODEL PARTS CHARACTERISTICS
Page 35 and 36:
II. DEVELOPMENT OF CTM FOR SFP The
Page 37 and 38:
7-9 October 2009, Leuven, Belgium r
Page 39 and 40:
7-9 October 2009, Leuven, Belgium a
Page 41 and 42:
7-9 October 2009, Leuven, Belgium I
Page 43 and 44:
7-9 October 2009, Leuven, Belgium u
Page 45 and 46:
7-9 October 2009, Leuven, Belgium s
Page 47 and 48:
7-9 October 2009, Leuven, Belgium N
Page 49 and 50:
7-9 October 2009, Leuven, Belgium s
Page 51 and 52:
7-9 October 2009, Leuven, Belgium D
Page 53 and 54:
7-9 October 2009, Leuven, Belgium b
Page 55 and 56:
7-9 October 2009, Leuven, Belgium C
Page 57 and 58:
OASIS files Final 2D layout design_
Page 59 and 60:
7-9 October 2009, Leuven, Belgium B
Page 61 and 62:
Page 63 and 64:
7-9 October 2009, Leuven, Belgium 3
Page 65 and 66:
7-9 October 2009, Leuven, Belgium b
Page 67 and 68:
Page 69 and 70:
7-9 October 2009, Leuven, Belgium F
Page 71 and 72:
Page 73 and 74:
Thermal behaviour causes some varia
Page 75 and 76:
on devices of long-term storage at
Page 77 and 78:
Page 79 and 80:
Fig. 3. Standard package simulation
Page 81 and 82:
Page 83 and 84:
∂ 2 T ∂ x ∂2 T T 2 ∂ y 2
Page 85 and 86:
Page 87 and 88:
q h T h 7-9 October 2009, Leuven, B
Page 89 and 90:
Page 91 and 92:
7-9 October 2009, Leuven, Belgium P
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
7-9 October 2009, Leuven, Belgium c
Page 99 and 100:
is used to model the forward polari
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
III. SUMMARY In this study it was s
Page 107 and 108:
where V is open-circuit voltage, r
Page 109 and 110:
V. THERMAL MATCHING IN LOW-DIMENSIO
Page 111 and 112:
Fig. 8. Low-power wireless medical
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
7-9 October 2009, Leuven, Belgium [
Page 125 and 126:
7-9 October 2009, Leuven, Belgium R
Page 127 and 128:
III. FINITE ELEMENT MODELLING OF BG
Page 129 and 130:
Page 131 and 132:
7-9 October 2009, Leuven, Belgium V
Page 133 and 134:
I OLED 7-9 October 2009, Leuven, Be
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
7-9 October 2009, Leuven, Belgium r
Page 145 and 146:
Fig. 5 Computed absolute temperatur
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
ETF ∫ VCO f vco (T) output 7-9 Oc
Page 155 and 156:
7-9 October 2009, Leuven, Belgium H
Page 157 and 158:
profile describes the temperature v
Page 159 and 160:
In Fig. 9 (a) the same integer work
Page 161 and 162:
7-9 October 2009, Leuven, Belgium H
Page 163 and 164:
Page 165 and 166:
meshes with highest heat removal ra
Page 167 and 168:
[5] P. Lee and S. Garimella, “Hot
Page 169 and 170:
Page 171 and 172:
7-9 October 2009, Leuven, Belgium o
Page 173 and 174:
In contrast to earlier results pres
Page 175 and 176: 7-9 October 2009, Leuven, Belgium (
Page 177 and 178: 7-9 October 2009, Leuven, Belgium 0
Page 179 and 180: 7-9 October 2009, Leuven, Belgium H
Page 181 and 182: hosing fittings etc.) were ‘off t
Page 183 and 184: 7-9 October 2009, Leuven, Belgium F
Page 185 and 186: ©EDA Publishing/THERMINIC 2009 174
Page 191 and 192: 7-9 October 2009, Leuven, Belgium H
Page 193 and 194: The spray boiling curves obtained i
Page 195 and 196: along the measure zone over the hea
Page 197 and 198: 7-9 October 2009, Leuven, Belgium T
Page 199 and 200: 7-9 October 2009, Leuven, Belgium f
Page 201 and 202: 7-9 October 2009, Leuven, Belgium t
Page 203 and 204: 7-9 October 2009, Leuven, Belgium P
Page 205 and 206: 7-9 October 2009, Leuven, Belgium a
Page 207 and 208: III. TEMPERATURE AND THICKNESS DEPE
Page 209 and 210: 7-9 October 2009, Leuven, Belgium d
Page 211 and 212: 7-9 October 2009, Leuven, Belgium s
Page 213 and 214: 7-9 October 2009, Leuven, Belgium h
Page 215 and 216: an increasing function of its TE fi
Page 217 and 218: 7-9 October 2009, Leuven, Belgium (
Page 219 and 220: The regime transition at λ β = 1.
Page 221 and 222: 7-9 October 2009, Leuven, Belgium C
Page 225: 7-9 October 2009, Leuven, Belgium k
Page 229 and 230: 7-9 October 2009, Leuven, Belgium r
Page 231 and 232: transient is measured by the transi
Page 235 and 236: 7-9 October 2009, Leuven, Belgium P
Page 237 and 238: 7-9 October 2009, Leuven, Belgium s
Page 239 and 240: 7-9 October 2009, Leuven, Belgium a
Page 241 and 242: onding it was compressed down to ~6
Page 243 and 244: 7-9 October 2009, Leuven, Belgium M
Page 245: 7-9 October 7-9 October 2009, 2009,
show all

Online proceedings - EDA Publishing Association

Create successful ePaper yourself

Delete template?

Save as template?