JP2001203308A - Semiconductor device cooling system and operation control method thereof - Google Patents

Abstract

[PROBLEMS] To provide a compact and reliable semiconductor device cooling system and a simple operation control method which keep a semiconductor chip such as an electronic computer, whose calorific value changes, at a constant low temperature and have high reliability. The heat medium of an evaporator for cooling a semiconductor module is cooled in a wet steam region, and further heats an unevaporated portion of the heat medium, so that a heat amount complementing means is provided on the downstream side of the cooler so as to be in an overheated region. In the cooling system provided with, the calorific value of the semiconductor module is known from the correlation between the calorific value and the surface temperature of the evaporator or the temperature and pressure of the internal heating medium, and the calorific value complementing means is controlled to adjust the heating amount. According to the method, a semiconductor chip can be maintained at a constant low temperature, and a reliable cooling system for a semiconductor device while ensuring reliability, and a simple control method thereof can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device cooling system and an operation control method thereof, and more particularly to a cooling system suitable for cooling semiconductor elements used in electronic equipment such as an electronic computer and an operation control method thereof. It is about.

[0002]

2. Description of the Related Art There are several types of semiconductor devices used in electronic computers. Among them, CMOS devices have been receiving attention in recent years because they can be processed at higher speed as they are cooled.

It is known that when a semiconductor device to be cooled is a CMOS device, its performance changes with temperature. The operating speed of this CMOS device increases as it cools at a lower temperature. For this purpose, the operation speed of the element is accelerated by keeping the element formed on the substrate surface at a low temperature.

Although there is no description of a CMOS device, a conventional example in which a refrigerating device is provided in a semiconductor device is disclosed in Japanese Patent Laid-Open No. 5-25 / 1993.
No. 9679. In this conventional example, a temperature sensor is attached to a heating element, and temperature information from this temperature sensor is input to a ROM containing a Mollier diagram that illustrates a change in state due to a change in the temperature of the refrigerant. . This RO
According to M, a built-in refrigeration / cooling device of an electronic device for controlling the rotation speed of a compressor for adjusting the internal pressure of the refrigeration / cooling system and controlling the opening / closing of an expansion valve for discharging the refrigerant is disclosed.

[0005]

In order to keep a semiconductor chip mounted on a semiconductor module at a low temperature as in the conventional cooling technique described above, a semiconductor device is cooled by attaching a cooler (evaporator) of a refrigerating device to the semiconductor module. The following problems arise.

[0006] An electronic computer using a CMOS element has a characteristic characteristic of CMOS in that the power consumption of the semiconductor module fluctuates with time due to the amount of arithmetic processing, and as a result, the heat generation of the semiconductor module fluctuates.

In the above conventional example, temperature information from a temperature sensor attached to a heating element is inputted to a ROM having a Mollier diagram in which changes in the state of a refrigerant are plotted, and converted into a refrigerant temperature to be converted into a refrigerant temperature. It controls the rotational speed of the compressor to adjust the pressure and controls the opening and closing of the expansion valve that discharges the refrigerant.

However, since the power consumption fluctuation of the semiconductor module, that is, the heat generation amount fluctuation is extremely fast, even if the rotation speed control of the compressor for adjusting the internal pressure of the refrigerating apparatus or the opening / closing control of the expansion valve for discharging the refrigerant is performed, the cooling is not performed. There is a problem that it takes time to reach the temperature of the container to a temperature corresponding to the temperature of the semiconductor module.

As a result, the refrigerating apparatus operates and cools even though the cooling of the semiconductor module is not necessary, or conversely, the refrigerating apparatus stops even though the cooling of the semiconductor module is necessary. Would.

In other words, there is a problem that a time lag occurs between the heat generation amount of the semiconductor module and the cooling power (refrigeration capacity) of the cooler (evaporator) of the refrigerating device.

As a result, the refrigerant in the evaporator partially and temporarily becomes an unevaporated liquid. When this unevaporated liquid is sucked into the compressor (liquid back), a malfunction occurs in the compressor, or the refrigerant largely enters the superheated gas area (superheat large). There was a problem that it was not possible to cool down the water uniformly.

An object of the present invention is to provide a refrigeration system by providing a control system capable of sufficiently following fluctuations in power consumption of a semiconductor module, that is, fluctuations in the amount of heat generated by a semiconductor module, which is a problem inherent to an electronic computer using a CMOS device. It is an object of the present invention to provide a compact semiconductor device cooling system and a cooling control method capable of keeping a semiconductor chip at a low temperature while ensuring the reliability of the device.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to provide a cooling system for a semiconductor device in which a cooling device for evaporating the unevaporated refrigerant liquid in the evaporator by a heating means provided on the outlet side of the cooler is mounted on a semiconductor module. In this case, the above is achieved by equalizing the refrigerant temperatures on the inlet side and the outlet side of the cooler.

[0014] It is also achieved that the refrigerant on the outlet side of the cooler has two phases, a liquid phase and a gas phase.

Further, a semiconductor device is provided with a cooling device which evaporates the unevaporated refrigerant liquid in the evaporator by heating means provided on the outlet side of the cooler and returns the evaporated refrigerant to the compressor. In the equipment cooling system,
This is achieved when the refrigerant at the inlet of the compressor becomes dry.

In a cooling system for a semiconductor device in which a refrigeration device for evaporating unevaporated refrigerant liquid in the evaporator by a heating means provided on an outlet side of the cooler is mounted on a semiconductor module for cooling, A control unit that stores a correlation between a change in surface temperature and a change in the amount of heat generated by the semiconductor module; and a detection unit that detects a surface temperature of the evaporator. The control unit receives a detection result from the detection unit as an input. Is achieved by controlling the refrigerating capacity of the refrigerating apparatus or the amount of heat generated by the heating means.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigeration cycle diagram showing one embodiment of the present invention.

In FIG. 1, one or a plurality of semiconductor chips 2 are mounted on a substrate 1 and a module cap 3 is mounted.
Is sealed. A large number of CMOSs are formed on one surface of the substrate.

Between the semiconductor chip 2 and the module cap 3, a heat conductor 4 such as a heat conductive grease or a combination fin is provided for transmitting heat. One semiconductor module is composed of the substrate 1, the semiconductor chip 2, the module cap 3, the heat conductor 4, and the like.

In order to know the heat value of the semiconductor module,
Evaporator surface temperature sensor 12 for measuring the evaporator surface temperature, evaporator internal heat medium temperature sensor 13 for knowing the evaporator internal heat medium temperature, evaporator internal temperature for evaporator inside heat medium pressure A heat medium pressure sensor 14 is provided. A temperature / pressure detector 5 for detecting the state values of these temperature sensors and pressure sensors and inputting them to the controller 6 is provided. An evaporator 10 of a refrigerating device is attached to the semiconductor module cap 3.

The refrigerating apparatus comprises a compressor 7, a condenser 8, an expansion valve 9 as a pressure reducing means, an evaporator 10 as a cooler, an electric assist heater 11 installed as a heating means on the downstream side of the evaporator 10. It is composed of The compressor 7, the expansion valve 9, and the electric assist heater 11 are controlled as necessary by the controller 6 that inputs a signal from the temperature / pressure detector 5.

The configuration of the present embodiment has been described above. Next, the operation of the present embodiment will be described.

The heat generated in the semiconductor chip 2 is transmitted to the module cap 3 via the heat conductor 4 and further transmitted to the evaporator 10. By setting the evaporation temperature of the evaporator 10 low, the temperature of the semiconductor chip 2 can be kept low. The speed of the CMOS device formed on the substrate 1 is increased by lowering the temperature.

FIG. 2 is a diagram for explaining a change in the amount of heat generated by the semiconductor device.

In FIG. 2, in the case of a semiconductor on which a CMOS element is mounted, the amount of heat generated varies with time.
The heat value of the semiconductor module also changes with time. The cooling capacity QR of the cooling device is equal to the heating quantity QAH of the heat quantity complementing means.
Is always heated during operation, the minimum heat value is QAHmin, and the heat value of the semiconductor module is QM.
Assuming that the maximum calorific value is QMmax, the relationship between the cooling calorie of the cooling device, the calorific value of the semiconductor module, and the calorific value of the calorific value complementing means is as follows: QR = QM + QAH (1)

As is apparent from the above relational expression, the cooling capacity QR of the refrigeration system is always larger than the heat generation QM of the semiconductor module. Now, the calorific value QM of the semiconductor module is
When the maximum heat generation amount is QMmax, the relationship is QR = QMmax + QAHmin (2).

When the calorific value of the semiconductor module is reduced, the heat medium cannot be evaporated by the evaporator 10 and the unevaporated liquid is sucked into the compressor 7 (liquid back), so-called liquid compression. In this embodiment, in order to avoid the occurrence of a malfunction in the compressor, in the present embodiment, as a heating device that is a calorific value complementing unit that complements a calorific value greater than or equal to a calorific value difference between the calorific value QM of the semiconductor module and the cooling calorific value of the evaporator, An electric assist heater 11 is provided at the outlet of the evaporator, on the downstream side.

FIG. 5 is a sectional view of the evaporator for explaining the measurement state of the evaporator surface temperature.

In FIG. 5, a heat medium such as Freon enters through the lower left inlet of the evaporator 10, flows inside the evaporator, and exits through the lower right outlet of the evaporator. In this embodiment, the heat medium enters at the evaporator inlet, travels up and down two times in the evaporator, and then exits at the evaporator outlet. During this time, the heat medium evaporates and exchanges heat with the heat generated by the semiconductor module due to the latent heat of evaporation. As a result, the semiconductor module is cooled. A temperature sensor for detecting the temperature is attached to the center evaporator surface of the flow path width of the heat medium flowing in the evaporator. Temperature sensors (thermocouples) are attached at substantially equal intervals from the inlet to the outlet in the order in which the heat medium flows. Here, the respective temperature sensors (thermocouples) are numbered from 01 to 16, and the surface temperature sensors are numbered. The measurement position was indicated by a number.

FIGS. 6 and 7 show actual examples measured in this way, and show the relationship between the calorific value of the semiconductor module and the evaporator surface temperature. The numerical values on the horizontal axis in FIGS. 6 and 7 are the temperature sensor (thermocouple) mounting positions 01 to 16 on the evaporator surface.

FIG. 3 is a diagram showing the correlation between the evaporator surface temperature and the heat value of the semiconductor module.

In FIG. 3, there is a correlation between the heat value of the semiconductor module and the evaporator surface temperature. When the calorific value QM of the semiconductor module increases as QM3>QM2> QM1, the temperature of the evaporator surface also increases. In addition to the operating conditions of the refrigeration cycle at this time, in particular, the circulation flow rate of the heat medium, that is, the rotation speed of the compressor 7 and the opening degree of the expansion valve 9 as the pressure reducing means, the heat generation amount of the semiconductor module and the surface temperature of the evaporator 10 The correlation is known in advance and the controller 6 is provided with this information. The refrigeration cycle condition at this time is given by the equation (1) shown above.
Is determined by

The calorific value QM of the semiconductor module can be known by knowing the surface temperature of the evaporator 10 in contact with the semiconductor module by the temperature sensor 12 and the temperature detector 5 based on this information.

The information of the temperature detector 5 is input to the controller 6, and any one of the rotation speed of the compressor 7, the opening degree of the expansion valve 9, and the heating amount of the electric assist heater 11, or each of them is transmitted via the controller. Is controlled as necessary so that the cooling heat amount QR of the refrigeration apparatus is always constant.

Thus, the reliability of the cooling device can be ensured and the semiconductor chip can be kept at a constant low temperature while responding to a rapid change in the heat generation amount of the semiconductor module.

In this embodiment, since the evaporator 10 of the cooling device is directly attached to the semiconductor module cap 3 and the temperature sensor 12 is attached to the surface of the evaporator 10, heat exchange between the evaporator 10 and the semiconductor module cap 3 is achieved. The temperature information due to the change in the amount of generated heat can be reliably grasped while performing well, and a compact cooling system control method can be provided.

Another embodiment of the present invention will be described with reference to FIG.

In order to know the heat value of the semiconductor module,
The temperature and pressure of the internal heating medium of the evaporator 10 are measured by a temperature sensor 13 and a pressure sensor 14 directly provided inside the evaporator.
Detected using the pressure detector 5, the detected information is input to the controller 6, and the
, The degree of opening of the expansion valve 9, or the amount of heating of the electric assist heater 11, which is the means for complementing the amount of heat, is controlled as necessary, and the cooling heat amount QR of the refrigerating device is always constant. Is to do so.

The evaporator 10 is made of a copper material or the like having a high thermal conductivity. The difference between the surface temperature of the evaporator and the temperature of the internal heating medium is the thermal resistance of the components. In other words, the temperature difference between the two is the difference of this thermal resistance, and usually,
In a member having a high thermal conductivity, the difference is small and has a correlation.

Therefore, the relationship between the heat value of the semiconductor module and the surface temperature of the evaporator shown in FIG. 3 can be replaced with the relationship between the heat value of the semiconductor module and the temperature of the internal heat medium of the evaporator. This information is stored in the controller 6 in advance. By knowing the temperature of the internal heat medium of the evaporator with the heat medium temperature sensor 13 and the temperature detector 5, the heat value of the semiconductor module can be known.

Further, there is a certain relationship between the temperature and the pressure of the heat medium. Therefore, similarly, there is a certain relation between the heat value of the semiconductor module and the pressure of the heat medium. By knowing the internal pressure of the heat medium using the heat medium pressure sensor 14 and the pressure detector 5, the amount of heat generated by the semiconductor module can be known.

Accordingly, a heat medium temperature sensor, a heat medium pressure sensor and a heat medium pressure sensor provided with either or both of the heat medium temperature and the heat medium pressure inside the refrigerator 10 which is in close contact with the semiconductor module. -Detect with the pressure detector 5 and input either or both of temperature information and pressure information to the controller 6,
The rotation speed of the compressor 7 and the expansion valve 9
And the amount of heating of the electric assist heater 11, which is the heat amount complementing means, is controlled as necessary, so that the cooling heat amount QR of the refrigerating apparatus is always constant.

Thus, the reliability of the cooling device can be ensured and the semiconductor chip can be kept at a constant low temperature while responding to a rapid change in the heat generation amount of the semiconductor module.

Another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a Mollier diagram.

In the refrigeration apparatus of this embodiment shown in the Mollier diagram in FIG. 4, the cooling heat of the heat medium for cooling the heat value QM of the semiconductor module includes the heat medium liquid and gas. Here, the point is within the wet steam range, and the heat amount for cooling the calorific value QM of the semiconductor module. Is the calorific value QAH of the electric assist heater 11 which is the calorific value complementing means attached to the downstream side of the evaporator.

The maximum heating value QMmax of the semiconductor module and the minimum heating amount QAHmin of the electric assist heater 11 as the heat amount supplementing means are determined from the above-described relational expression (2). In this state, the dryness X of the heat medium at the outlet of the evaporator is X ≦ 0.9.
The rotation speed of the compressor 7 of the refrigeration cycle is kept constant, and the opening of the expansion valve 9 as the pressure reducing means is kept constant.

Therefore, in the present embodiment, the heating amount QAH of the electric assist heater 11, which is the heating amount supplementing means, is controlled so that the non-evaporated liquid of the heating medium does not remain with respect to the fluctuation of the heating value QM of the semiconductor module. Is increased or decreased to respond.

The reason for setting the dryness X at the outlet of the evaporator 10 as a cooler to X ≦ 0.9 is that the influence of heat conduction due to the heat conduction of the piping at the outlet of the evaporator is eliminated and the pressure loss, which is a characteristic of the heat medium, is eliminated. By using a region having a small temperature, the width of change of the evaporation temperature of the heat medium due to the pressure loss is reduced, the surface temperature of the evaporator 10 is kept constant, and the semiconductor module is kept at a constant low temperature.

FIGS. 6 and 7 show actual measurement examples when the dryness X at the outlet of the evaporator 10 is X = 1.0 (FIG. 6) and X = 0.9 (FIG. 7).

The flow rate of the heating medium (fluorocarbon) is as shown in FIG.
In the case of FIG. 7, the same flow rate flows through the evaporator at 9 g / s.
The difference between the two is the amount of heat generated by the semiconductor module (the amount of cooling of the evaporator). The former is 16.9 W / cm ² , and the latter is 1
0.6 W / cm ² , and the former has a larger calorific value (cooling amount of the evaporator).

In the former case of FIG. 6, the dryness X of the heat medium at the outlet of the evaporator is X = 1.0. Looking at the relationship between the surface temperature (vertical axis) and the temperature measurement position (horizontal axis) of the evaporator surface at this time, the surface of the heat medium at the evaporator outlet side and the measurement positions at positions 14, 15, and 16 were determined. It can be seen that the temperature is higher than the surface temperature at the other measurement positions, that is, at the positions of the inlets 01 to 13 of the evaporator. Moreover, the evaporator inlet 0
The surface temperatures at positions 1 to 13 are constant.

On the other hand, in the latter case of FIG. 7, since the dryness X at the outlet of the evaporator is set to X = 0.9, the surface temperature of the evaporator is changed from the inlet 01 of the evaporator to the position 16 near the outlet. It can be seen that the surface temperature is constant up to this point.

Under the above conditions, the relationship between the temperature of the evaporator surface and the semiconductor module shown in FIG. 3 is known in advance, and such information is provided in the controller 6.

With respect to the fluctuation of the heat value QM of the semiconductor module, the rotation speed of the compressor 7 is kept constant, and the expansion valve
The opening degree of the compressor 7 is kept constant, and only the heating amount QAH of the electric assist heater 11, which is the heat amount supplementing means, is increased or decreased to control the change in the rotation speed of the compressor 7 and the pressure reducing means. Eliminating fluctuations in the refrigeration cycle due to changes in the opening degree of the expansion valve 9, speeding up the stabilization of the refrigeration cycle, and controlling the heating amount QAH of the electric assist heater 11 as the heat amount supplementing means can be easily controlled, and fluctuations in the cooling temperature. The width can be reduced.

By knowing the surface temperature of the evaporator 10 shown in FIG. 1 by the attached temperature sensor 12 and temperature detector 5, the controller 6 having a correlation between the evaporator surface temperature and the heat generation amount of the semiconductor module is provided. By inputting the information and knowing the heat generation amount of the semiconductor module via the controller 6, controlling the heating amount QAH of the electric assist heater 11 which is the heat amount complementing means, and operating the cooling device, the surface temperature of the semiconductor module is kept at a constant low temperature. And a compact cooling device.

Another embodiment of the present invention will be described with reference to FIGS. 1, 3 and 4.

In the above embodiment, the calorific value of the semiconductor module is detected by detecting the surface temperature of the evaporator 10 during operation from the correlation between the evaporator surface temperature detected in advance and the calorific value of the semiconductor module.

In the present embodiment, since there is a correlation between the surface temperature of the evaporator 10 and the temperature of the heat medium inside the evaporator 10 and the pressure of the heat medium, the calorific value of the semiconductor module and the inside of the evaporator 10 are determined in advance. The correlation between the heat medium temperature and the internal heat medium pressure is detected in the same manner as in FIG. 3 (not shown), and the heat medium temperature sensor 13 provided inside the evaporator 10 shown in FIG.
Alternatively, one or both of the heat medium pressure sensors 14 are transferred by the temperature / pressure detector 5, and the information is provided with the temperature of the heat medium inside the evaporator, and the correlation between the heat medium pressure and the calorific value of the semiconductor module. Input to the controller 6.

From the prepared information, the heat value of the semiconductor module is known by the controller 6, and as shown in the Mollier diagram of FIG. 4, the dryness X of the heat medium at the outlet of the evaporator is X ≦ 0.
Only the heat quantity QAH of the electric assist heater 11, which is the heat quantity complementing means, is controlled to increase or decrease through the controller 6 so as to be 9.

In the present embodiment, by operating the cooling device in this manner, the influence of heat due to heat conduction at the outlet of the semiconductor module can be eliminated, and the semiconductor module can be cooled in a region where the pressure loss, which is the characteristic of the heat medium, is small. Therefore, the surface temperature of the semiconductor module can be cooled to a constant low temperature, and a compact cooling device can be provided.

As described above, according to the present invention, the calorific value of the semiconductor module, that is, the required cooling power of the cooling device evaporator is detected via the controller, and the rotational speed of the compressor, the opening degree of the expansion valve,
By controlling any one or each of the heating amounts of the heat amount complementing means, even if the load of the semiconductor module is fluctuated quickly, the cooling can be surely performed and the reliability of the refrigeration system is ensured.

Further, by detecting the required cooling power of the cooling device evaporator and controlling any one or each of the number of rotations of the compressor, the opening degree of the expansion valve, and the amount of heating of the calorific value supplementing means, a high semiconductor module load can be obtained. This ensures reliable cooling and ensures the reliability of the refrigerator.

[0064]

According to the present invention, the operation and reliability can be ensured, the semiconductor chip can be kept at a constant low temperature, and a compact device and a simple control method can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating a change in the amount of heat generated by a semiconductor device.

FIG. 3 is a diagram showing a correlation between an evaporator surface temperature and a heat value of a semiconductor module.

FIG. 4 is a diagram for explaining the operation of the present invention.

FIG. 5 is a sectional view of a cooler showing one embodiment of the present invention.

FIG. 6 is a graph showing the degree of dryness of a heat medium (fluorocarbon).

FIG. 7 is a graph showing the degree of dryness of a heat medium (fluorocarbon).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Semiconductor chip, 3 ... Module cap, 4 ... Thermal conductor, 5 ... Temperature / pressure detector, 6 ... Controller, 7 ... Compressor, 8 ... Condenser, 9 ... Decompression means (expansion valve) Reference numeral 10: evaporator (cooler), 11: calorific value supplementing means (electric assist heater), 12: evaporator surface temperature sensor, 13: evaporator internal heat medium temperature sensor, 14: evaporator internal heat medium pressure sensor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Keizo Kawamura 502, Kandachi-cho, Tsuchiura-shi, Ibaraki Pref.Mechanical Research Laboratories, Inc. In the Enterprise Server Division (72) Inventor Akio Ide 1 Horiyamashita, Hadano-shi, Kanagawa F-term in the Enterprise Server Division, Hitachi, Ltd. 5F036 AA01 BA03 BA08 BA24 BB53 BB56

Claims (4)

[Claims] 1. A cooling system for a semiconductor device in which a cooling device for evaporating unevaporated refrigerant liquid in the evaporator by a heating means provided on an outlet side of a cooler is mounted on a semiconductor module. A cooling system for the semiconductor device, wherein the temperature of the refrigerant at the outlet and the temperature of the refrigerant at the outlet are equalized. 2. The cooling system for a semiconductor device according to claim 1, wherein the refrigerant on the outlet side of the cooler has two phases, a liquid phase and a gas phase. 3. A semiconductor module having a cooling device mounted on a semiconductor module, wherein a non-evaporated refrigerant liquid in the evaporator is evaporated by a heating means provided on an outlet side of the cooler and the evaporated refrigerant is returned to a compressor. A cooling system for a semiconductor device, wherein a refrigerant at an inlet of the compressor is dried. 4. A cooling system for a semiconductor device in which a refrigeration device for evaporating an unevaporated refrigerant liquid in the evaporator by a heating means provided on an outlet side of the cooler is mounted on a semiconductor module for cooling. A control unit that stores a correlation between a change in surface temperature and a change in the amount of heat generated by the semiconductor module; and a detection unit that detects a surface temperature of the evaporator. The control unit receives a detection result from the detection unit as an input. Controlling the refrigerating capacity of the refrigerating device or the amount of heat generated by the heating means, and a method for controlling the operation of the semiconductor device.