JP2010251432A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device utilizing radiation cooling wherein a solid alumina material having high emissivity in the infrared range is brought into contact with the core or the package of a semiconductor integrated circuit with relatively high driving electric power such as a compact CPU or ASIC serving as a kernel to enhance or maintain performance in compact equipment via a metal plate for heat transfer which has high thermal conductivity such as, for example, an aluminum plate and a copper plate to convert thermal energy into infrared light and then emit it. <P>SOLUTION: The cooling device includes the metal plate for heat transfer mounted on the top surface of the core or package of the semiconductor integrated circuit, and an alumina plate further mounted on the metal plate for heat transfer and composed principally of the alumina material of ≥0.8 in emissivity for radiation cooling, the area of the heat transfer plate and the area of the alumina plate being larger than that of the top surface of the core or package. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cooling plate using an alumina material and a cooling method, and more particularly, to a cooling device using an alumina material having a high emissivity that can be expected for efficient radiative cooling. More specifically, the present invention has recently been remarkably progressed in the downsizing, multi-function, and high-speed, and has been widely used for personal use such as notebook computers, netbooks, personal digital assistants (PDAs), and high-performance mobile phones (smartphones). The present invention relates to a cooling device capable of suitably releasing heat generated when a highly integrated circuit is driven in a sealed space in a main body of a thin small device such as a device.

  In recent years, the rapid spread of various communication infrastructures including wireless local area networks (wireless LANs) including the outdoors has led to the demand for portable computers such as notebook computers and netbooks, personal portable devices such as PDAs and smartphones. The demand for multifunctional and high-speed small electronic devices is increasing due to demand for product differentiation. Up to now, the multi-functionalization and high-speed operation of these devices have been realized along with the progress of micro-processing technology of semiconductor integrated circuits, but in recent years, the development of micro-processing technology has slowed due to physical limitations. In order to solve this problem, introduction of a technique for stacking integrated circuit chips is being studied.

  However, in high-density mounting such as a laminated structure, heat is concentrated on a small area and the internal temperature rises, so that an error in driving an integrated circuit is likely to occur. Another approach is to reduce the power consumption of personal computer CPUs and apply them to mobile devices. However, because it is based on a CPU that generates a lot of heat, it is inherently limited due to power consumption constraints. It is the present situation that we do not draw out the function of. Furthermore, development of a CPU using an integrated circuit having a laminated structure based on this CPU is also being studied. Under such circumstances, there is an increasing demand for a small cooling device with good cooling efficiency, but none satisfies this requirement sufficiently. In general, semiconductor integrated circuits such as CPUs, ASICs, and FPGAs, which are the core for improving the performance of personal mobile devices, are expected to have higher functionality and higher speeds, as estimated from the specifications of conventional relatively large stationary notebook computers. The drive power of possible small CPUs, ASICs and FPGAs is expected to be ~ 20W. However, the current driving power of semiconductor integrated circuits such as small CPUs, ASICs, and FPGAs, which is the core of maintaining the performance of current portable devices, is about 2 W to 4 W. The cause of the current situation is not only that the capacity of the battery built in the portable device is insufficient, but also the problem of heat generation is considered to be one of the main causes. This is because, in general, when the temperature of the semiconductor integrated circuit rises to approximately 90 ° C. or higher during driving of the semiconductor integrated circuit, a leak current is generated in the insulating film to induce an error (see the following cited document).

Y. Kurita, et al. “A 3D Stacked Memory
Integrated on a Logic Device Using SMAFTI
Technology ”Electronic Components and Technology
Conference, pp821-829, 2007.

  The reason for this situation is that the conventional cooling method relies on a fin-type heat sink that requires a large heat medium in principle and heat conduction through the substrate. This is due to the fact that no reasonable method has been studied. In order to solve this problem, the development of providing a micro flow path as a cooling mechanism in an interposer for relaying between an integrated circuit chip having a different terminal pitch and a semiconductor integrated circuit and a main substrate is underway (see below). (Refer to the literature), the micro-fabrication technology is used for forming these flow paths, and there is a high possibility that the manufacturing process increases and the cost is high, and it can be said that the solution is more suitable for high-end products than personal portable terminals.

JU Knickerbocker, et al. “System-on-Package
(SOP) Technology, Characterization and Applications ”Electronic
Components and Technology Conference, pp415-421, 2006.

Calvin. R. King, Jr., et al. “3D Stacking of
Chips with Electrical and Microfluidic I / O Interconnects ”Electronic Components and Technology Conference, pp1-7, 2008.

M. Yu, et al. “Fabrication of Silicon Carriers with TSV Electrical Interconnections
and Embedded Thermal Solutions for High Power 3-D Package ”Electronic Components and Technology Conference, pp24-28, 2008.

M. Sunohara, et al. “Silicon Interposer with
TSVs (Through Silicon Vias) and Fine Multilayer Wireing ”
Electronic Components and Technology Conference, pp847-852, 2008.

  In Patent Document 1, the alumina content is 95% by weight or more, preferably 97% by weight to 98% by weight, the thermal emissivity is 0.93 to 0.98, and the thermal conductivity is 30 to 60 W / m · K. 20 (mm; width) × 40 (mm; length) × 6 (mm; thickness) of a ceramic heat-radiating solid material having a surface (upper surface) temperature of 98 to 100 ° C. (mm; width) x 40 (mm; length) x 3 (mm; thickness) mica heater) When in close contact, the temperature dropped to 67 ° C after 10 minutes and maintained that temperature Are disclosed (paragraphs 0016, 0020 and Table 3).

  In Patent Document 2, a heat radiation film, a heat radiation structure, a heat radiation member, and a heat radiation device that are suitable for thin or small electronic devices such as notebook personal computers and flat panel displays and that can efficiently dissipate heat. 4 layers of an aluminum layer 21 and a SiO 0.98 layer 22a / SiO 1.20 layer 22b / SiO 1.70 layer 22c are formed on the surface of the casing (base material) 20 of the electronic device. A heat radiation structure 23 in which a wavelength selective radiation film 22 composed of a three-layered film is formed on a light-reflective aluminum layer 21 by coating, and an electronic device provided with this heat radiation structure 23 on the outer surface It is disclosed.

JP 2006-298703 A JP 2005-144985 A

  However, Patent Document 1 shows that ceramic heat-radiating solids having an alumina content of preferably 97 wt% to 98 wt% are suitable for cooling. There is no indication as to whether it can be used.

  Patent Document 2 (Japanese Patent Laid-Open No. 2005-144985) proposes a radiation cooling method using a heat radiation film composed of silicon oxide, ticker silicon and polyvinyl chloride or polyvinyl fluoride. Even with a high value of 0.7 to 0.9, a heat dissipation film is used, so an increase in thermal resistance due to the generation of voids and the addition of the thermal resistance of the adhesive itself are expected when fixing to the heat source. It is not clear whether it is suitable for use in personal portable devices and improving performance.

As described above, the driving power of a semiconductor integrated circuit used in a personal portable device is currently about 2 to 4 W, even if the driving power is designed to be higher than this. The current situation is that it relies on a technique for reducing drive power and limiting performance. In general, in a semiconductor integrated circuit, speeding up depends on driving power, and if a driving power of up to about 20 W can be input, it can generally cope with multi-function speeding up. The maximum area of the cooling device that can be used for personal portable devices is approximately 100 mm × 100 mm, and is advantageously a flat plate. It is an object of the present invention to provide a device that maintains a temperature lower than 90 ° C., which is a general temperature that induces an error of a semiconductor integrated circuit, by providing a heat dissipation mechanism having a thermal energy discharge capability of 20 W / 10000 mm ² with this flat plate. And

  In addition, since radiative cooling is a cooling mechanism with no power supply, it is common to mount an air cooling fan of about 1/10 of this output in a conventional semiconductor integration of about 20 W of driving power. Power saving of about 10 is possible (referred to the Intel D945GCLF2 board mounted fan). In the present invention, a metal plate for heat transfer having a high thermal conductivity such as an aluminum plate or a copper plate is applied to a semiconductor integrated circuit having a relatively high driving power, such as a small CPU or ASIC, which is the core of performance improvement or maintenance in a small device. An object of the present invention is to provide a cooling device using radiant cooling that contacts a solid alumina material having a high emissivity in the infrared region through heat and converts thermal energy into infrared light and emits it.

As a result of intensive studies by the inventor, in order to efficiently dissipate the heat generated by driving a semiconductor integrated circuit in a personal portable device to the outside, a technique that satisfies both the small portability and the efficient heat dissipation characteristics is necessary. It is. For this purpose, an alumina material having a high emissivity, which can dissipate heat better in a flat plate structure, is brought into direct contact with the surface of the semiconductor integrated circuit package, and the heat is transferred to the alumina material flat plate by heat conduction, and these are transferred to infrared light. The present inventors have considered that it is sufficient to use radiant cooling that is radiated after being converted into the present invention. That is, in order to solve the above problems, a cooling device of the present invention includes a heat transfer metal plate placed on the core or package surface of a semiconductor integrated circuit, and a radiation cooling plate further placed on the heat transfer metal plate. And an alumina plate mainly composed of an alumina material having an emissivity of 0.8 or more, wherein the area of the heat transfer plate and the area of the alumina plate are more than the area of the surface of the core or package. Is also large. Preferably, a load of 85 kgf / m ² or more is applied to the alumina plate in a state where the ceramic plate is placed on the core or package surface.

  A thin, small and highly efficient cooling device that can efficiently cool a semiconductor device with a large amount of heat generation such as a CPU by heat radiation without the need for cooling fins that are bulky in the height direction or a cooling fan that requires driving power. Can be provided. In particular, a small and highly efficient cooling device suitable for cooling a semiconductor device of a small electronic device sealed in a resin or metal housing can be provided.

It is a conceptual diagram of the cooling device of this invention. It is a figure which shows the data at the time of calculating | requiring the emissivity of the alumina (Nishimura Ceramics N-9H) used for this invention experiment. It is a conceptual diagram which shows the apparatus used for the characteristic investigation of the cooling plate of this invention. It is a figure which shows the time change of the surface temperature of an alumina flat plate and a copper flat plate. It is a figure which shows the temperature characteristic to the saturation temperature of 80 degreeC in the alumina flat plates A, B, and C from which dimensions differ, respectively. It is a figure which shows the relationship between the thermal radiation energy in the case of saturation temperature 80 degreeC, and an alumina flat plate heat sink area. It is a figure which shows the relationship (saturation temperature of 80 degreeC) of the load and thermal radiation energy in the alumina heat sink from which each area differs. It is a figure which shows the relationship (saturation temperature 80 degreeC) of the alumina board thickness and the energy which can be thermally dissipated. It is a figure which shows the comparison (saturation temperature of 80 degreeC) of the surface temperature at the time of using the alumina flat plate heat sink of B in FIG. It is a figure which shows the comparison (surface saturation temperature of 80 degreeC) of the surface temperature at the time of pinching | interposing between the heaters the metal plate of the same size as the alumina flat plate heat sink of B in FIG. 10 is a diagram for comparing the heat radiation energy and alumina plate area dependence of the alumina flat plate + metal plate + heater of FIG. 10 and the alumina flat plate + heater of FIG. It is sectional drawing which shows the side surface of the experimental apparatus used for experiment of Examples 1-4. It is sectional drawing which shows the side surface of the experimental apparatus used for experiment of Examples 5-7. It is sectional drawing which shows the side surface of the experimental apparatus used for experiment of Examples 8-10. It is sectional drawing which shows the side surface of the experimental apparatus used for experiment of Examples 11-13. It is sectional drawing which shows the side surface of the experimental apparatus used for experiment of Example 14. FIG.

  Hereinafter, preferred embodiments of a cooling plate and a cooling method according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows a simple configuration diagram illustrating the principle of the present invention. FIG. 1 shows a semiconductor integrated circuit and a package 12 placed with an alumina plate 11 for cooling superimposed thereon. Heat is transferred from the core or package 12 of the semiconductor integrated circuit to the alumina plate 11 by heat conduction. Heat is transferred from the alumina plate 11 to the external space by radiation cooling by infrared radiation. In general, alumina, zircon, alumina nitride, and the like that are ceramics are known to have high emissivity, but alumina is particularly inexpensive, easy to purify, and easy to increase emissivity, and Since it has strength compared to other ceramics, it is possible to reduce the thickness, and since it has a wide range of applications, it was used as the material of the present invention.

Conventionally, there is an example in which a predetermined heat is applied to a heat sink using an alumina material, and the temperature is measured. However, there is no example of specifically examining how much heat can be radiated in a cooling device using an alumina material. Therefore, the present inventor examined in detail the proof that the heat radiation is radiative cooling and the heat radiation capacity in the following procedure, and that the alumina flat plate (alumina heat sink 31) has a discharge capacity of about 20 W / 10000 mm ^2. Verified. The purity of the alumina flat plate used here is about 99%, and the emissivity is about 0.97 (room temperature to 100 ° C.). The emissivity is calculated from the ratio of the radiation when the radiator is an ideal object (black body) and the radiation of the alumina flat plate (ratio of all wavelengths) using a Perkin Elmer SYSTEM2000 FTIR measuring instrument at the Fine Ceramics Center. Calculated. An example of the emissivity of the alumina flat plate measured at that time is shown in FIG. 2 (0,97 at 30 ° C., 80 ° C. and 100 ° C.).

Fig. 3 shows the experimental apparatus used in this study. The main configuration is a thin resistance heater (resistance heater) 32 having a size of 20 mm (X) × 40 mm (Y) × 2 mm (Z) and a flat alumina heat sink 31 having the same shape and different emissivity. The alumina heat sink 31 has a relatively high emissivity value of 0.97, and the copper heat sink for comparison has a low emissivity value of 0.1. The heater surface of the resistance heater 32 is covered with stainless steel (the emissivity is as low as 0.05) to reduce the influence of radiation (cooling) of the heater itself. The flat alumina heat sink 31 is pressed with a load of 400 kgf / m ^{2 in} the Z-axis direction by a plurality of needles.
The needle is based on an organic material, and its thermal conductivity is as low as 0.15 to 0.25 W / mK, so it is thermally isolated by fixing the needle, and the movement of heat energy due to heat conduction is ignored in the experiment. obtain.

  This experimental apparatus is housed in a sealed glass container (359 mm (X) × 220 mm (Y) × 262 mm (Z)) in order to avoid the influence of outside air and wind. Infrared radiation from the alumina heat sink 31 passes through the glass container and is absorbed by the black cloth on the outer periphery thereof. Through this experiment, it was confirmed that the temperature in the container did not change from room temperature and was no wind (the wind speed was 0 below the detection lower limit in the measurement of Anoster Model AM-B11 / 11-2111 (manufactured by Nippon Chemical Industry Co., Ltd.)). .05 m / sec). Therefore, it can be seen that the air cooling effect is eliminated as much as possible in this experimental system (in general, a flat plate heat sink does not show much air cooling effect at a wind speed of 0 to 3 m / sec. See the following cited reference). Under this condition, a constant power is supplied to the heater in the range of about 5 W for 30 to 120 minutes, and the temperature of the resistance heater 32 surface is measured with a thermocouple to determine the saturation temperature.

Y. Kurita, et al. “A 3D Stacked Memory
Integrated on a Logic Device Using SMAFTI
Technology ”Electronic Components and Technology
Conference, pp821-829, 2007.

Further, in an application experiment described later, the dependency of the supplied power (heat release energy from the alumina heat sink 31) when the heater surface reaches the saturation temperature of 80 ° C. is examined. At that time, in order to facilitate the handling of the experiment, a relatively large size (24 mm (X) × 49 mm (Y) × 1.9 mm (Z)) heater and three types of alumina heat sinks are combined (alumina heat sink). 31A. 50 mm (X) x 50 mm (Y) x 5 mm (Z), Alumina heat sink 31 B. 75 mm (X) x 75 mm (Y) x 5 mm (Z), Alumina heat sink 31 C. 100 mm (X) x 100 mm (Y) x 5 mm (Z)).

  FIG. 4 shows the cooling effect of the alumina heat sink 31 having different emissivities. In the figure, the curve indicating the heater surface temperature is the result of the alumina heat sink 31 and the copper flat plate (the heater size and the heat sink size are 20 mm (X) × 40 mm (Y) × 2 mm (Z)). The supply power was fixed at 5 W for the heater assumed to be a semiconductor integrated circuit for 30 minutes, and the temperature rise on the heater surface was measured. When the heat sink is not used (control), the heater surface temperature rapidly rises from room temperature to 97 ° C. and thereafter becomes constant. This temperature is a temperature at which an error occurs in driving a general semiconductor integrated circuit.

  Similar results are observed in the temperature curve when a copper heat sink is used. The temperature rises from room temperature to 88 ° C. and then saturates. This temperature is close to an allowable temperature in normal semiconductor integrated circuit driving. On the other hand, when the alumina heat sink 31 is used, the saturation temperature is 66 ° C., which is a low temperature that is superior to the copper heat sink (this temperature is sufficiently low in LSI driving). Temperature.) In general, it is known that the thermal conductivity of copper material is about 6 times higher than that of alumina material, but the experimental device of this experiment is thermally isolated, and the saturation temperature depends on the magnitude of the emissivity. Therefore, it can be seen that a flat plate material having a high emissivity is very effective for obtaining an efficient cooling effect due to radiation cooling.

Next, in order to understand the cooling characteristics of the alumina heat sink 31, the power supplied to the heater at a saturation temperature of 80 ° C. (Generally, the thermal design power of the semiconductor integrated circuit is indicated by the energy supplied to the semiconductor integrated circuit. The energy supply to the heater here is equivalent to the thermal design power, and it is an indicator of the energy required to be released.) This temperature is an allowable range in normal semiconductor integrated circuit driving. 5 are the results for the following heat sink sizes (alumina heat sink 31A.50 mm (X) × 50 mm (Y) × 5 mm (Z), alumina heat sink 31 B.75 mm (X) × 75 mm (Y) × 5 mm). (Z)
Alumina heat sink 31C. 100 mm (X) × 100 mm (Y) × 5 mm (Z)).

As can be seen from FIG. 5, the supply power (release energy) in the smallest-sized alumina heat sink 31A is 5.75 W, which is the lowest. Next, in order of size, the alumina heat sink 31B and the alumina heat sink 31C are 7.63 W,
It was 10.61W. These results indicate that a large size heat sink corresponds to a large supply power (emission energy), and as a result, it is possible to release energy from 5.75 W to 10.61 W.

  In order to better understand this result, FIG. 6 shows the relationship between the heat sink area obtained from the experiment of FIG. 5 and the supply energy (discharge energy). As can be seen from the figure, in the range of the experiment, the supply energy (release energy) is almost directly proportional to the heat sink area, and this relationship can be expressed as [Equation 1].

  E = AS [Formula 1]

Where E is the emission energy, S is the heat sink area, and A is a proportionality constant. It should be noted here that, as described in the previous chapter, the experimental system is configured so as not to be affected as much as possible by the air cooling effect and heat conduction, and the radiant energy depends on the area in the experiment. One interpretation is the effect of radiative cooling, and the relationship is expressed by the well-known Stefan Boltzmann equation of [Equation 2].

E = εδT ⁴ S [Formula 2]

[Equation 2] where E is the emission energy, ε is the correction factor (1 for black bodies), δ is the Stefan-Boltzmann constant (5.67 × 10 ^-12 [W m ^-2 K ^-4 ]), T is the absolute temperature, S Is the heat sink area. From the above, it was found that the cooling effect by the alumina heat sink 31 is radiative cooling, and the maximum capacity is about 10 W / 10000 mm ² . Although it has not reached 20 W / 10000 mm ² as the initial purpose, it is very effective industrially to be able to dissipate heat up to this point in a sealed space equivalent to no wind with a simple structure (an effect will be described in the examples).

In order to further increase the radiation capacity to about 20 W / 10000 mm ² , the following investigation was conducted. Up to now, data has been acquired by applying a load of 400 kgf / m ^{2 in} the (Z) axis direction to fix the heater as if it were an alumina heat sink 31 and a semiconductor integrated circuit. It was investigated whether this weighting was a reasonable weight to obtain a stable result. FIG. 7 is a graph plotting the weight dependence of the thermal radiation energy when the heater temperature is the saturation temperature of 80 ° C.

As can be seen from the figure, the thermal radiation energy becomes constant by applying a weight of 170 kgf / m ² or more. This indicates that the reduction in thermal resistance between the alumina heat sink 31 and the heater affects the amount of heat radiation energy. If a reduction in heat release of about 10% is allowed, a weight of 85 kgf / m ² or more can be said to be an effective weight. The thermal resistance is considered to be generated by the alumina heat sink 31 and the resistance heater 32 or the semiconductor integrated circuit gap. For this reason, by applying a viscous material (silicon grease, conductive grease, etc.) that fills the gap between the alumina heat sink 31 and the semiconductor integrated circuit or resistance heater 32, a heat dissipation amount of about 85 kgf / m ² is obtained without load. be able to. It is necessary to follow these know-how for improvement.

  Further, it was examined whether the thickness (5 mm) of the alumina heat sink 31 used in FIGS. 5 and 6 is appropriate. Here, for a 100 mm × 100 mm alumina heat sink 31C and a 50 mm × 50 mm alumina heat sink 31A at a saturation temperature of 80 ° C., the energy capable of thermal radiation was examined when the thicknesses were changed. The experimental method is the same as in FIG. The results are shown in FIG. As can be seen from the figure, both alumina plates have good heat radiation efficiency when the thickness is 3 mm to 8 mm. Conventionally, when investigating the radiable energy at an arbitrary saturation temperature, it has been common knowledge to examine the area according to the Stefan Boltzmann equation. However, it was newly found that there is a dependence on thickness.

  The details of this mechanism are unknown, but it is presumed as follows. First, it is presumed that the amount of radiation that can be emitted increases as the number of molecules of the main component of alumina increases. This can be inferred from the fact that the radiable energy is dependent on the area. From the tendency of FIG. 8, when the number of molecules increases in the thickness direction, when the infrared light generated from the portion close to the heat source passes toward the far portion, the amount of passage is suppressed by some absorption and reflection. . Thereby, it is considered that a thickness suitable for the radiable energy is generated. Therefore, in the experiments of FIGS. 5 and 6, using 5 mm, which is a thickness suitable for increasing the amount of heat radiation, is a coincidence, but is considered appropriate. In FIG. 4, a 2 mm thick alumina heat sink has a high heat radiation capability of obtaining a saturation temperature of about 66 ° C. when 5 W is applied to the resistance heater. This is because the resistance heater and the alumina heat sink are the same size and the thermal resistance is small. It is considered that better results can be obtained by setting the thickness to about 5 mm.

Further, in order to increase the radiation capacity to about 20 W / 10000 mm ² , with respect to the alumina heat sink 31B (75 mm (X) × 75 mm (Y) × 5 mm (Z)) in FIG. 6, the resistance heater surface, the center of the alumina heat sink 31B, The temperature at the end of the heat sink of the alumina heat sink 31B was examined. The results are shown in FIG.

The temperature at the center of the alumina heat sink 31B was 80 ° C., the same as the resistance heater surface, but the temperature at the end of the heat sink of the alumina heat sink 31B was 73 ° C., which was 7 ° C. lower. The present inventor considers that heat dissipation performance can be further improved by improving the heat conduction at the end of the alumina heat sink 31B, and heat transfer with good heat conduction between the alumina heat sink 31B and a heater that is regarded as a semiconductor integrated circuit such as a CPU. I tried to sandwich a metal plate (aluminum plate). The size of the heat transfer metal plate (aluminum plate) viewed from the upper surface is larger than that of a heater that is regarded as a semiconductor integrated circuit, and is the same size as the alumina heat sink 31B. The results are shown in FIG. The weight was 400 kgf / m ² as before.

  As in FIG. 9, the temperature of the heater surface and the temperature of the center of the alumina heat sink 31B were 80 ° C. Further, the difference from FIG. 8 is that the temperature of the end of the heat sink of the alumina heat sink 31B is 80 ° C., and the heat release energy is increased to 15.1W. Similar results were confirmed with other metal plates (stainless steel, copper).

  The area dependence of the heat release energy at a saturation temperature of 80 ° C. in the structure shown in FIG. 10 was examined. The results are shown in FIG.

As can be seen from the graph of FIG. 11, the heat radiation energy from the alumina heat sink 31B could be increased about twice by inserting a heat transfer metal plate between the alumina flat plate and the heater as shown in FIG. The reason why there is such an increase due to a temperature difference of several degrees at the end of the heat sink of the alumina heat sink 31B in FIGS. 9 and 10 is unknown, but the heat of the heater can be efficiently transferred by sandwiching a metal plate with good thermal conductivity. It is considered that the heat can be efficiently radiated from the peripheral portion of the alumina heat sink 31B. As a result, a large heat dissipation effect was obtained. From the above, a flat plate heat sink having a discharge capacity of about 20 W / 10000 mm ² which was the original purpose was realized. Further, even with a structure that does not use a metal plate as shown in FIG. 9, a discharge capability of about 10 W has been obtained, and thus a technique for selectively using the required capacity and cost can be established.

Currently, in the case of using the semiconductor integrated circuit of about thermal design output 10 W, 45 mm but (X) × 45mm (Y) × 45mm (Z) Size cooling fin heat sink is used, the area 2000 mm ² order of FIG. 11 ( It can be expected that an alumina heat sink (about 45 mm (X) × 45 mm (Y) × 5 mm (Z)) can be substituted.

Therefore, in a small desktop computer in which an air-cooled fin heat sink of 45 mm × 45 mm × 45 mm size and a CPU with a thermal design output of 8 W (the core part is exposed and the area of the core part is about 50 mm ² ) are used. A load of 100% was applied to the CPU for 60 minutes, and a 45 mm × 45 mm × 5 mm alumina flat plate heat sink 31D and an aluminum plate were stacked and used as shown in FIG. Further, an alumina flat plate heat sink 31D was used on top of it, and the following examples were also compared with the case where they were placed in the same order. The wind speed in the sealed container is 0.05 m / sec. The distance between the resin wall surface of the sealed container and the surface of the alumina flat plate heat sink 31D was 10 mm. As a result, it was found that the performance was almost equivalent (CPU surface temperature was 50 ° C .: allowable temperature of 90 ° C. or less). This uses an alumina flat plate heat sink 31D with an emissivity of 0.97, but even with an alumina flat plate heat sink with an emissivity of 0.80, the CPU surface temperature is about 60 ° C., which is below the allowable temperature. The above description is based on the assumption that the core part of the CPU is exposed. However, in the type of CPU where the core is not exposed, a ceramic package (surface area of about 200 mm ^{2 to} 900 mm ² , that is, 15 mm × 15 mm to 30 mm × The aluminum plate heat sink 31D is stacked on the aluminum plate for heat conduction more than this package and the alumina plate heat sink 31D is stacked on the aluminum plate (in the following embodiments, the alumina plate heat sink 31A or the alumina plate is used instead of the alumina plate heat sink 31D). The same except that a heat sink 31C may be used).

  Moreover, although the space | interval with the resin wall surface of the airtight container which opposes the widest surface which the alumina flat plate heat sink 31D opposes is set to 0 mm, 5 mm, and 10 mm, the surface temperature of CPU is 50 to 60 degreeC, and it has influence on operation | movement. There wasn't. The temperature of the resin wall surface at this time was 30 to 35 ° C. The temperature of the resin wall surface is a temperature that does not cause a burn or the like even if human skin contacts the resin wall surface.

  Moreover, although the space | interval with the metal wall surface (black coating) of the airtight container which opposes the widest surface which the alumina flat plate heat sink 31D exposes was 1 mm, 5 mm, and 10 mm, the surface temperature of CPU is 50 to 60 degreeC. There was no effect on operation. The resin temperature at this time was 35-40 degreeC. I never got burned.

  This CPU has a lineup of 4W in the same series, and this is installed in Netbook (trademark) which is a portable device for individuals. 8W products are also required to be mounted, but they are difficult to dissipate and are only applied to small desktops. According to the present invention, it is possible to reduce the heat sink volume, and it is possible to apply it to a personal portable device. This completes the description of the radiation cooling performance by the combination of the integrated circuit and the alumina heat sink.

Next, a description will be given of an embodiment in which the CPU to which the alumina heat sink is attached is operated in a situation close to an actual mounting form. In the following Examples 1 to 16, the core part of the CPU is exposed, the area of the core part is about 50 mm ² (10 mm × 5 mm) with ^two cores (dual core), and the CPU with the thermal design output of 8 W Is used. FIG. 12 shows an experimental apparatus according to Examples 1 to 4.

Example 1
In a computer on which a 45 mm × 45 mm × 45 mm size air-cooled fin heat sink and a CPU 125 with a thermal design output of 8 W are mounted, this air-cooled fin heat sink is removed and a 50 mm × 50 mm × 5 mm alumina flat plate heat sink 123 (its material and size are (It is the same as the above-mentioned alumina heat sink 31A) and a load of 400 kgf / m ² is applied to the alumina flat plate heat sink 123 by the weight 121 and the weight support 122 so as to contact the upper surface of the CPU 125 on the CPU base 126. The CPU 125 was operated with a load of 100% usage for 30 minutes. The wind speed in the hermetic container 127 is 0.05 m / sec. The distance between the widest surface where the alumina flat plate heat sink 123 is exposed and the wall surface of the resin plate 124 facing it is 10 mm. The wind speed is 0.05 m / sec or less. The temperature of the alumina heat sink flat plate 123 at that time was measured. The saturation temperature of the alumina flat plate heat sink 123 was 70 to 80 ° C., which is 85 ° C. or less of the allowable limit temperature. The wall surface temperature of the resin plate 124 was about 30 ° C. In FIG. 12, the resin plate 124 has four holes for allowing the legs of the weight support 122 to pass through, and two of the holes are shown in a sectional view as seen from the side. Therefore, in FIG. 12, the resin plate 124 is shown as being divided into three parts. The same applies to the other drawings (the metal plate 134 in FIG. 13, the resin plate 145 in FIG. 14, the metal plate 155 in FIG. 15, and the resin plate 165 in FIG. 16).

Example 2
In Example 1, the distance between the widest surface where the alumina flat plate heat sink 123 is exposed and the wall surface of the resin plate 124 facing the surface is 5 mm. The saturation temperature of the alumina flat plate heat sink 123 was 70 to 80 ° C., which is 85 ° C. or less of the allowable limit temperature. The wall surface temperature of the resin plate 124 was about 30 ° C.

Example 3
In Example 1, the distance between the widest surface where the alumina flat plate heat sink 123 was exposed and the wall surface of the resin plate 124 facing the surface was set to 0 mm. The saturation temperature of the alumina flat plate heat sink 123 was 70 to 80 ° C., which is 85 ° C. or less of the allowable limit temperature. The wall surface temperature of the resin plate 124 was about 35 ° C.

Example 4
In Example 1, the wind speed was tested in the range of 0.05 to 3.0 m / sec, but each temperature had only a change of about 0 to 3 ° C.

Next, the experimental apparatus figure concerning Examples 5-7 is shown in FIG.
Example 5
45mm × 45mm × 45mm size air-cooled fin heat sink Thermal design output 8W CPU 135 In the computer, this air-cooled fin heat sink is removed, and the 50mm × 50mm × 5mm alumina flat plate heat sink 133 (the material and size are described above) Is installed with a load of 400 kgf / m ² by a weight 131 and a weight support 132 so as to come into contact with the CPU 135 on the CPU base 136, and the usage rate of the CPU 135 is 100% for 30 minutes. It was operated with a load applied. The distance between the widest surface where the alumina flat plate heat sink 133 is exposed and the wall surface of the opposing metal plate 134 is 10 mm. The wind speed is 0.05 m / sec or less. The surface of the metal plate 134 facing the alumina flat plate heat sink 133 was painted with a matte black. The temperature of the alumina flat plate heat sink 133 at that time was measured. The saturation temperature of the alumina flat plate heat sink 133 was 70 to 80 ° C., which is an allowable limit temperature of 85 ° C. or less. The wall surface temperature of the metal plate 134 was about 30 ° C.

Example 6
In Example 5, the interval between the widest surface where the alumina flat plate heat sink 133 is exposed and the wall surface of the metal plate 134 facing the surface was set to 5 mm. The saturation temperature of the alumina flat plate heat sink 133 was 70 to 80 ° C., which is an allowable limit temperature of 85 ° C. or less. The wall surface temperature of the metal plate 134 was about 35 ° C.

Example 7
In Example 5, the distance between the widest surface where the alumina flat plate heat sink 133 is exposed and the wall surface of the metal plate 134 facing it was set to 0 mm. The saturation temperature of the alumina flat plate heat sink 133 was 70 to 80 ° C., which is an allowable limit temperature of 85 ° C. or less. The wall surface temperature of the metal plate 134 was about 40 ° C.

Next, an experimental apparatus diagram according to Examples 8 to 10 is shown in FIG.
Example 8
45mm × 45mm × 45mm size air-cooled fin type heat sink Thermal design output 8W CPU 146 is mounted on this computer, this air-cooled fin type heat sink is removed and 45mm × 45mm × 5mm alumina flat plate heat sink 143 (the material and size are the same as above) And the aluminum plate 144 having the same dimensions as the alumina flat plate heat sink 143 (thickness is 1 mm to 5 mm), but in contact with the upper surface of the CPU 146 on the CPU base 147. Thus, the load of 400 kgf / m ² was applied by the weight 141 and the weight support 142 so that the CPU 146 was operated with a load of 100% utilization for 30 minutes. The distance between the widest surface where the alumina flat plate heat sink 143 is exposed and the wall surface of the resin plate 145 facing it was set to 10 mm. 14, the area of the lower surface of the aluminum plate (heat transfer metal plate) 144 is larger than the area of the core portion on the upper surface of the CPU 146, and the area of the upper surface of the aluminum plate 144 is substantially the same as the area of the lower surface of the alumina flat plate heat sink 143. is there. Further, the upper surface of the CPU 146 does not need to be in contact with the central portion of the lower surface of the aluminum plate (heat transfer metal plate) 144, and may be in contact with one side of the aluminum plate (metal plate for heat transfer) 144, The same applies to other examples using the following aluminum plates (metal plates for heat transfer). The wind speed is 0.05 m / sec or less. The temperature of the alumina flat plate heat sink 143 at that time was measured. The saturation temperature of the alumina flat plate heat sink 143 was 50-60 ° C., which is 85 ° C. or less, which is an allowable limit temperature. The wall surface temperature of the resin plate 145 was about 30 ° C.

Example 9
In Example 7, the distance between the widest surface where the alumina flat plate heat sink 143 was exposed and the wall surface of the resin plate 145 facing the surface was 5 mm. The saturation temperature of the alumina flat plate heat sink 143 was 50-60 ° C., which is 85 ° C. or less, which is an allowable limit temperature. The wall surface temperature of the resin plate 145 was about 35 ° C.

Example 10
In Example 7, the distance between the widest surface where the alumina flat plate heat sink 143 was exposed and the wall surface of the resin plate 145 facing the surface was set to 0 mm. The saturation temperature of the alumina flat plate heat sink 143 was 50-60 ° C., which is 85 ° C. or less, which is an allowable limit temperature. The wall surface temperature of the resin plate 145 was about 40 ° C.

Next, FIG. 15 shows an experimental apparatus according to Examples 11-13.
Example 11
45mm × 45mm × 45mm size air-cooled fin type heat sink Thermal design output 8W CPU 156 is mounted on this computer, this air-cooled fin type heat sink is removed and 45mm × 45mm × 5mm alumina flat plate heat sink 153 (the material and size are the same as above) And the aluminum plate (heat transfer metal plate) 154 having the same dimensions as the alumina flat plate heat sink 153 (thickness is 1 mm to 5 mm), and are stacked in the order shown in the figure. A load of 400 kgf / m was applied by a weight 151 and a weight support 152 so as to be in contact with the upper surface of the CPU 156, and the CPU 156 was operated with a load of 100% utilization of the CPU 156 for 30 minutes. The distance between the widest surface where the alumina flat plate heat sink 153 is exposed and the wall surface of the metal plate 155 opposite to the widest surface was set to 10 mm. In FIG. 15, the area of the lower surface of the aluminum plate 154 is larger than the area of the core portion of the CPU 156, and the area of the upper surface of the aluminum plate 154 is substantially the same as the area of the lower surface of the alumina flat plate heat sink 153. The wind speed is 0.05 m / sec or less. The air volume in the sealed container is 0.05 m / sec. The surface of the metal plate 155 facing the alumina flat plate heat sink 153 was painted with a matte black. The temperature of the alumina flat plate heat sink 153 at that time was measured. The saturation temperature of the alumina flat plate heat sink 153 was 50 to 60 ° C., which is 85 ° C. or less of the allowable limit temperature. The wall surface temperature of the metal plate 155 was about 30 ° C.

Example 12
In Example 10, the distance between the widest surface where the alumina flat plate heat sink 153 is exposed and the wall surface of the metal plate 155 facing the surface is 5 mm. The saturation temperature of the alumina flat plate heat sink 153 was 50 to 60 ° C., which is 85 ° C. or less of the allowable limit temperature. The wall surface temperature of the metal plate 155 was about 35 ° C.

Example 13
In Example 11, the distance between the widest surface where the alumina flat plate heat sink 153 was exposed and the wall surface of the metal plate 155 facing the surface was set to 0 mm. The saturation temperature of the alumina flat plate heat sink 153 was 70 to 80 ° C., which is 85 ° C. or less of the allowable limit temperature. The wall surface temperature of the metal plate 155 was about 40 ° C.

  Next, an experimental apparatus diagram according to Example 14 is shown in FIG.

Example 14
45mm x 45mm x 45mm size air-cooled fin-type heat sink + A computer with a thermal design output 20W CPU 166 on which an electric fan is mounted. This air-cooled fin-type heat sink + electric fan is removed, and a 100mm x 100mm x 5mm alumina plate A heat sink 163 (the material and size of which are the same as those of the above-described alumina heat sink 31C) and an aluminum plate (a metal plate for heat transfer) 164 having substantially the same dimensions as the alumina flat plate heat sink 163 (thickness is 1 to 5 mm) are shown in the figure. Stacked in the order shown, installed with a load of 400 kgf / m ² by a weight 161 and a weight support 162 so as to contact the upper surface of the CPU 166 on the CPU base 167, and a load of 100% usage of the CPU 166 for 30 minutes. It was put into operation. The distance between the widest surface where the alumina flat plate heat sink 163 is exposed and the wall surface of the resin plate 165 facing it was set to 10 mm. In FIG. 16, the area of the lower surface of the aluminum plate 164 is larger than the area of the core portion of the CPU 166, and the area of the upper surface of the aluminum plate 164 is substantially the same as the area of the lower surface of the alumina flat plate heat sink 163. The wind speed is 0.05 m / sec or less. The temperature of the alumina flat plate heat sink 163 at that time was measured. The saturation temperature of the alumina flat plate heat sink 163 was 60 to 70 ° C., which is an allowable limit temperature of 85 ° C. or less. The wall surface temperature of the resin plate 165 was about 30 ° C. This is the end of the description of each embodiment.

  As described above, according to the cooling device of the present invention, the heat conducting metal plate having a larger area than the semiconductor device and the alumina heat sink are in close contact with the highly heat-generating semiconductor device, so that highly efficient cooling is achieved by heat radiation. In particular, when used in a small electronic device in which a semiconductor device is encapsulated in a resin housing or metal housing, heat can be efficiently dissipated through the resin housing or metal housing, and no cooling fan is required. It is possible to provide a very suitable cooling device that is small in direction and does not require cooling fins and does not require cooling power.

11 Alumina plate 12 Semiconductor integrated circuit and package 31 Alumina heat sink 32 Resistance heater 121 Weight 122 Weight support 123 Alumina plate heat sink 124 Resin plate 125 CPU
126 CPU base 127 Sealed container 131 Weight 132 Weight support 133 Alumina flat plate heat sink 134 Metal plate 135 CPU
136 CPU base 137 Sealed container 141 Weight 142 Weight support 143 Alumina flat plate heat sink 144 Aluminum plate (metal plate for heat transfer)
145 Resin plate 146 CPU
147 CPU base 148 Sealed container 151 Weight 152 Weight support 153 Alumina flat plate heat sink 154 Aluminum plate (metal plate for heat transfer)
155 Metal plate 156 CPU
157 CPU base 158 Sealed container 161 Weight 162 Weight support 163 Alumina flat plate heat sink 164 Aluminum plate (metal plate for heat transfer)
165 Resin plate 166 CPU
167 CPU base 168 Airtight container

Claims (6)

A heat transfer metal plate placed on the core or package surface of a semiconductor integrated circuit, and an alumina mainly composed of an alumina material having a radiation rate of 0.8 or more, which is further placed on the heat transfer metal plate. A cooling device composed of a plate,
A cooling device for a semiconductor integrated circuit, wherein an area of the heat transfer metal plate and an area of the alumina plate are larger than an area of a surface of the core or the package. The cooling device according to claim 1, wherein the alumina plate is used by applying a load of 85 kgf / m ² or more to the alumina plate in a state where the alumina plate is placed on a core or a package surface. The semiconductor integrated circuit, the heat transfer metal plate, and the alumina plate are accommodated in a casing constituted by a plurality of walls,
The distance between the wall surface of the housing and the wall surface of the housing facing the upper surface which is the widest surface of the alumina plate is 0 mm to 10 mm,
The cooling device according to claim 1 or 2, wherein the alumina plate radiates heat through the wall surface of the opposing housing.   4. The cooling device according to claim 3, wherein the wall surface of the casing is made of metal or resin.   The cooling device according to any one of claims 1 to 4, wherein the alumina plate has a thickness of 3 mm to 8 mm. The cooling according to any one of claims 1 to 5, wherein when the thermal design power of the semiconductor integrated circuit is 10 W or less, the area of the widest surface of the alumina plate is 10,000 mm ² or less. apparatus.

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