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In 1967 IBM demonstrated an optical data link between two computers at the 1967 Montreal Exposition [15]. An optical diode emitting light in the infrared range and dissipating 3 watts was key to the operation of the link. To ensure satisfactory and reliable operation of the optical diode it was mounted on a two-stage cascaded thermoelectric cooler with the cold side surface tempera- ture at -25 °C and the hot side temperature at 55 OC. As shown in Figure 4, the heat load of 68 watts from the diode and thermoelectric cooler was rejected to ambicnt air via a small water-cooling loop. It may be noted that the

Figure 4 In 1967 IBM demonstrated an optical data link between two computers at the 1967 Montreal Exposition [15]. An optical diode emitting light in the infrared range and dissipating 3 watts was key to the operation of the link. To ensure satisfactory and reliable operation of the optical diode it was mounted on a two-stage cascaded thermoelectric cooler with the cold side surface tempera- ture at -25 °C and the hot side temperature at 55 OC. As shown in Figure 4, the heat load of 68 watts from the diode and thermoelectric cooler was rejected to ambicnt air via a small water-cooling loop. It may be noted that the

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ure 1. Relative performance factors (normalized with respect to operation at 100 °C) for 1.5 V CMOS circuits as a function of operating temperature [5].
ure 1. Relative performance factors (normalized with respect to operation at 100 °C) for 1.5 V CMOS circuits as a function of operating temperature [5].
Although the principle of thermoclectricity dates back to the discovery of the Peltier effect in 1834, there was little practical application of the phenomenon until the middle 1950s. Prior to then the poor thermoelectric propertics of known matcrials made them unsuitable for use in a practical refrigerating device. As discussed by Nolas et al. [6], from the mid-1950s to the present the major thermoelectric material design approach was that introduced by A.V. Ioffe. This approach was to select semiconducting compounds of heavy elements from the lower right of the periodic table and then to reduce the lattice thermal conductivity by forming mixed crystals. This technique led to compounds such as Bi2Te3 which is currently used in thermoclectric modules. These materials made possible the development of practical thermoelectric devices for attaining temperatures below ambient without the use of vapor-compression refrigeration. The application of thermoclectric cooling modules to cool electronics was discussed by Kraus [7] in the first book devoted to cooling clectronic equipment. Thermoelectric moduies offer the potential to augment the cooling of electronic module packages to: 1) reduce chip operating temperatures at a given module heat load, or 2) allow higher module heat loads at a given chip temperature level. Thermoclectric cooling modules also offer the advantages of being compact, quiet, and having no moving parts. In addition, the degree of cooling may be readily controlled by means of the current supplied to the thermoelcctrics. Fleurial et al. [11] reported that in 1991 JPL started a broad search to identify and develop advanced thermoelectric materials. Among the materials consid- ered, skutterudite and Zn4Sb3-based materials appeared particularly promising and several of these materials are being developed. ZT values equal to or greater than | have been obtained for these materials over different ranges of temperature varying from 375 to 975 K. Unfortunately, to be particularly useful for electronic cooling applications improvements are necded in ZT over the tempcrature range of 300 to 325 K or below. Another Sixteenth IEEE SEMI-THERM™ Symposium
Although the principle of thermoclectricity dates back to the discovery of the Peltier effect in 1834, there was little practical application of the phenomenon until the middle 1950s. Prior to then the poor thermoelectric propertics of known matcrials made them unsuitable for use in a practical refrigerating device. As discussed by Nolas et al. [6], from the mid-1950s to the present the major thermoelectric material design approach was that introduced by A.V. Ioffe. This approach was to select semiconducting compounds of heavy elements from the lower right of the periodic table and then to reduce the lattice thermal conductivity by forming mixed crystals. This technique led to compounds such as Bi2Te3 which is currently used in thermoclectric modules. These materials made possible the development of practical thermoelectric devices for attaining temperatures below ambient without the use of vapor-compression refrigeration. The application of thermoclectric cooling modules to cool electronics was discussed by Kraus [7] in the first book devoted to cooling clectronic equipment. Thermoelectric moduies offer the potential to augment the cooling of electronic module packages to: 1) reduce chip operating temperatures at a given module heat load, or 2) allow higher module heat loads at a given chip temperature level. Thermoclectric cooling modules also offer the advantages of being compact, quiet, and having no moving parts. In addition, the degree of cooling may be readily controlled by means of the current supplied to the thermoelcctrics. Fleurial et al. [11] reported that in 1991 JPL started a broad search to identify and develop advanced thermoelectric materials. Among the materials consid- ered, skutterudite and Zn4Sb3-based materials appeared particularly promising and several of these materials are being developed. ZT values equal to or greater than | have been obtained for these materials over different ranges of temperature varying from 375 to 975 K. Unfortunately, to be particularly useful for electronic cooling applications improvements are necded in ZT over the tempcrature range of 300 to 325 K or below. Another Sixteenth IEEE SEMI-THERM™ Symposium
Figure 3. Structure for a thin film thermoclectric device (adapted from Fleurial and Vandersande [9] ).
Figure 3. Structure for a thin film thermoclectric device (adapted from Fleurial and Vandersande [9] ).
Figure 5. Cross-sectional view of memory array chambcr utilizing thermoelectric cooling. In another application, it was necessary to cool chips on wafers under test prior to dicing. To do this wafers were held on a water-coolcd platform by means of a vacuum. It was determined that in order to cool a chip under test it was nccessary to provide a water tempcra- ture of 20°C entering the platform. Cooling water was
Figure 5. Cross-sectional view of memory array chambcr utilizing thermoelectric cooling. In another application, it was necessary to cool chips on wafers under test prior to dicing. To do this wafers were held on a water-coolcd platform by means of a vacuum. It was determined that in order to cool a chip under test it was nccessary to provide a water tempcra- ture of 20°C entering the platform. Cooling water was
Figure 6. Cross-sectional view of thermoelectric wafer test cooling system.
Figure 6. Cross-sectional view of thermoelectric wafer test cooling system.
R, is the thermal resistance across the interface between the cap and heat sink base or between the cap and the cold-side of the thermoelectric module. The thermoclectric hot-side temperature is related to the cooling fluid temperature, To, Lo
R, is the thermal resistance across the interface between the cap and heat sink base or between the cap and the cold-side of the thermoelectric module. The thermoclectric hot-side temperature is related to the cooling fluid temperature, To, Lo
Table 1. Chip Temperature and Allowable Power Dissipation Equations for Thermoelectric Module Augmentation.
Table 1. Chip Temperature and Allowable Power Dissipation Equations for Thermoelectric Module Augmentation.
Figure 9. Lotus 1-2-3 T.E. spreadsheet calculator screen.
Figure 9. Lotus 1-2-3 T.E. spreadsheet calculator screen.
ure 10. Module temperature reduction versus module power for air or water-cooled 126 mm x 126 mm multi-chip modules.
ure 10. Module temperature reduction versus module power for air or water-cooled 126 mm x 126 mm multi-chip modules.
Related topics:
HistoryComputer Aided ManufacturingHeat pumpThermal ResistanceThermoelectric CoolingElectronics PackagingComputer CoolingPower DissipationApplication Software
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