Heat generation from silicon microprocessors is highly non-uniform both spatially and temporally, with localized high heat fluxes that vary with the workload. Current electronics cooling technologies based on conduction and convection can potentially cool moderately high heat fluxes by utilizing either novel passive heat transport materials (such as carbon nanotubes) or advanced heat exchangers (such as microchannels), respectively. But they cannot provide site-specific and/or on-demand localized cooling of high heat flux regions, thus resulting in over-designed, inefficient, and bulky thermal systems. In contrast, solid state (thermoelectric) refrigeration can provide rapid, localized, and on-demand active cooling, as well as increased cooling power densities.

Chip-scale thermoelectric coolers for high-performance microelectronics can be integrated into microprocessor and electronics packages for high heat-flux thermal management for demanding computation. In the example below, a thermoelectric cooler (TEC) is placed inside the chip package, where the cooler is integrated onto conventional copper heat spreaders (Figure 1), just like the type already used in chip packaging to disperse heat.

Figure 1. TEC for microprocessor hot‐spot thermal management. At left, the TEC with quarter shown for size. At right, illustration showing location of the TEC in the actual circuit‐level implementation.

Usually this piece of copper is in close contact with the chip, but we have put the 0.4 mm2, only 100-m-thick cooler between the chip and the copper. When the TEC is turned on, it cools a localized “hot” (>1200 W/cm2) region on the chip by about 15°C (Figure 2).

Figure 2. Cooling data for the TEC.

This is significant, because generally speaking, for each 5°C increase in chip temperature, there is a many-fold decrease in a chip’s reliability and performance. In the demonstration, only one TEC was used, however, three or four TECs could cover the hottest areas of multi-core chips (Figure 3).

Figure 3. This figure shows several high‐power‐density spots on a state‐of‐the‐art microprocessor chip that may need to be thermally managed for effective operation. Data courtesy of Intel Corp.

Another example is managing hot spots in graphic card chips (figure 4).

Figure 4. TEC on a graphics add‐in card. Here a hot spot has developed in the main data processing chip in the center of the graphic card. The TEC could help selectively manage such hot spots without the need to cool the entire graphic card. Note: To protect client confidentiality, the specific location of the hot spot on the graphics card is not shown but schematically indicated.

Here a hot spot has developed in the main data processing chip in the center of the graphic card. The TEC selectively manages such hot spots without the need to cool the entire graphic card.

Microscale thermoelectric coolers can be used to cool many electronic components, such as infrared arrays, and to enable efficient refrigeration/thermal management systems for many electronic, optoelectronic, and power electronic applications, bio-applications, such as high-speed polymerase chain reaction (PCR) applications, and other high-performance thermal management applications.

This approach for hot spot cooling is described in detail in an article entitled "On-chip cooling by superlattice-based thin-film thermoelectrics," published in Nature Nanotechnology (2009). See an abstract at here. Hot spot cooling is covered by U.S. Patent 7,523,617, "Thin film thermoelectric devices for hot spot thermal management in microprocessors and other electronics."

Nextreme Products for Hot Spot Cooling

UPF40 - ideal for applications with high heat-flux requirements.  More >

HV14 - a high voltage, low current thermoelectric cooler optimized for standard circuitry and power requirements.  More >

Note: Semi-custom or custom solutions may be required to integrate thin film TEC’s into heat spreaders. Nextreme offers a variety of services for the modeling, design and engineering of heat rejection systems. For more information, visit the Nextreme Labs page.