JP2001147251A - Temperature distribution controller for thermostatic oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermostatic oven which holds its intake side at the same temperature with its blowout side as much as possible when air is sent in a next board rack by suppressing a temperature difference between both sides on the same burn-in board as much as possible and eliminating impedance to an air velocity between board racks and is simple and adaptive to a high load by making it possible to decrease a temperature error based upon prescribed temperature as a thermostatic oven which has board racks mounted with burn-in boards and arrayed in an array or laterally in arrays. SOLUTION: A board rack on which burn-in boards mounted with many devices is installed in the thermostatic oven; and one end of a heat pipe is installed where the temperature in the thermostatic oven desires to be lowered and the other end is installed where the temperature in the thermostatic oven desires to be held higher than specific temperature to hold the temperature on the turn-in boards in the thermostatic oven uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature distribution control device for a thermostatic oven used in a burn-in process of a device such as an IC or an LSI, which can equalize the temperature on each burn-in board in the thermostatic oven. It is an object of the present invention to provide a new temperature distribution control device for a thermostat.

[0002]

2. Description of the Related Art Conventionally, a burn-in test in which a device composed of a semiconductor integrated circuit such as an IC or LSI is placed in a furnace of a thermostat and a power supply voltage or a test pattern signal is externally applied to the device in the furnace for testing. To ensure device reliability.

In the burn-in test, the temperature of a furnace in a thermostat is set to a high temperature or a low temperature, a test pattern signal is applied for a long time to apply a stress, and an intended failure is detected. In the burn-in test, since the test time for each device is long, thousands to 10,000 devices are simultaneously placed in the furnace to prevent the test time and cost from being increased.

Further, in recent years, devices made of semiconductor integrated circuits such as the ICs and LSIs have been reduced in size, and the density of devices mounted on the same area of a burn-in board has been increasing. The increase in the number of mountings in the same area in this way means that the load during the burn-in process increases accordingly. Therefore, in order to use the same thermostat or a miniaturized thermostat to reduce the load, the conditions in the burn-in process must be grasped and solved.

At present, a board rack having a plurality of burn-in boards on which a large number of devices are mounted is installed inside the constant temperature bath using a board rack which also functions as a transportable jig. The arrangement of the board racks and the number of used board racks vary depending on the capacity of the device and the outer diameter of the thermostat. The burn-in process is performed with these components mounted. In the normal burn-in process, the burn-in test is performed while always controlling the temperature. It should be noted that this temperature-controlled temperature distribution has a range in which a temperature error from a specified temperature is recognized.

On the other hand, hot air or cold air set at a predetermined temperature is sent to the board rack by a blower fan or the like, and the temperature of the furnace in the constant temperature bath is maintained at the predetermined temperature. However, as shown in FIG. 5, the air blown into the board rack from the outlet side of the blower fan is heated by the heat generated from the device, and the mounting density of the device on the burn-in board and the mounting of the burn-in board on the board rack are increased. The calorific value increases according to the density. Therefore, the calorific value must be evenly distributed in the constant temperature bath to ensure constant temperature accuracy.

In the conventional thermostat, the above-mentioned temperature change is adjusted by increasing the wind speed of the air blown from the blow-out side of the blower fan toward the board rack, or positioned on the opposite side of the board rack with respect to the blow-out side. The suction amount of the air on the suction side is adjusted, and the air pressure is adjusted to a certain level. For example, as shown in FIG. 6 and FIG.
A sirocco fan or pump 12 and a stepless automatic damper 13 are attached to 1, and the exhaust air in the thermostat and room air are mixed and sent into the thermostat by the sirocco fan or pump 12. The temperature is adjusted by synchronizing the operation of the sirocco fan or the pump 12 and the opening and closing of the stepless automatic damper 13 with the set value of the temperature in the constant temperature bath.

Further, by heating or cooling with a heater, a refrigerator, or the like, the temperature change in the thermostat due to the calorific value of the device has been supplementarily adjusted.

[0009]

As described above, in the constant temperature bath, an air blowing side and an air suction side are arranged to circulate air in a certain direction. When there is no load on the temperature side in the thermostat, there is almost no temperature difference between the blow-out side and the suction side. However, when a temperature load is applied to the thermostat, the temperature rises from the blowing side to the suction side. This is because the heat of the device is picked up as it is.

[0010] Even with a single row of burn-in boards, this temperature difference occurs between the blow-out side and the suction side. For example, if the board racks are arranged in two rows as shown in Fig. 1, the temperature difference may be doubled. Can be In fact, it is very difficult to control such a temperature difference reliably and quickly in the conventional control using a heater, a refrigerator, or the like.

Therefore, the temperature distribution control device for a thermostatic bath according to the present invention, in a thermostatic bath in which board racks on which burn-in boards are mounted are arranged in a single row or in a plurality of rows in a horizontal direction, minimizes the temperature difference between both sides on the same burn-in board. The air is sent to the next board rack so that the temperature of the suction side is the same as that of the blowing side when air is sent to the next board rack so as not to hinder the air pressure between the board racks. And since such a uniform temperature adjustment is possible and the cooling means which can quickly cool to the predetermined temperature is provided, it is possible to reduce the temperature error from the specified temperature, and to achieve a simple and high load. It is intended to provide a thermostatic bath that can respond.

That is, the heat pipe utilizes a very quick heat transfer. One end of the heat pipe is installed at a portion where the temperature in the thermostat is to be lowered, and the other end is lower than a predetermined temperature in the thermostat. An object of the present invention is to provide a temperature distribution control device for a thermostatic bath, which can be instantaneously cooled down by setting up at a temperature site, an atmosphere heated up by a load based on the test of the site.

[0013]

SUMMARY OF THE INVENTION A temperature distribution control apparatus for a thermostat according to the present invention comprises a thermostat in which a board rack in which a plurality of burn-in boards on which a large number of devices are mounted is mounted is provided. The temperature on each burn-in board in the thermostat is made uniform by installing it at the location where you want to lower the temperature in the thermostat and by installing the other end at a temperature lower than the predetermined temperature in the thermostat. It is assumed that.

[0014] The temperature distribution control device for a thermostatic bath according to the present invention comprises:
By installing heat pipes along the direction of air flow in the constant-temperature bath in a constant-temperature bath in which a board rack with multiple burn-in boards with multiple devices mounted is installed, Characterized in that the temperature in the above is made uniform.

Therefore, according to the present invention, by setting one end of the heat pipe at a position in the constant temperature bath where the temperature is desired to be lowered, and setting the other end at a position lower than a predetermined temperature in the constant temperature bath, A new type of temperature distribution control in a constant temperature bath that enables the very quick heat transfer of the pipes to be used effectively and allows the atmosphere that has been heated up by the load from the above test to be instantly cooled down. Equipment can now be provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a temperature distribution control device for a thermostatic bath according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing one embodiment of a temperature distribution control device for a thermostatic bath of the present invention, FIG. 2 is a schematic diagram showing another embodiment of the temperature distribution control device for a thermostatic bath of the present invention, and FIG. FIG. 4 is a schematic diagram showing a temperature change under a test load.

In FIG. 1, reference numeral 1 denotes a thermostat, in which a pair of board racks 3-1 and 3-2 on which a plurality of burn-in boards on which a number of devices are mounted are mounted are installed inside the furnace body 2. The constant temperature bath 1 is provided with an air circulation mechanism (not shown). And, -Y ° C. of the thermostat 1
Is circulated and mixed with the temperature X ° C. in the board racks 3-1 and 3-2 to adjust the temperature.

In the thermostat 1 having the above structure, a heat pipe unit 5 is provided between the pair of board racks 3-1 and 3-2 in the furnace main body 2 and has an upper end protruding above the furnace main body 2. Installed. This heat pipe unit 5
The inside of the sealed metal pipe container is evacuated, and a small amount of water or CFC liquid is sealed. Then, for example, when one end is heated and the other end is cooled, the internal liquid becomes [boiling].
A [vapor transfer]-[condensation]-[reflux] cycle occurs, and heat is transported very quickly through the exchange of latent heat.

That is, by installing one end of the heat pipe unit 5 at a location where the temperature in the thermostat 1 is to be lowered and the other end at a location in the thermostat 1 at a temperature lower than a predetermined temperature, The temperature on each burn-in board in 1 is equalized. Figure 1 shows the temperature change at that time.
This is shown in the lower graph.

In the second embodiment shown in FIG. 2, reference numeral 1 denotes a thermostat, and a burn-in board 6 on which a number of devices are mounted.
Are mounted inside the furnace main body 2. The constant temperature bath 1 is provided with an air circulation mechanism (not shown).
Is circulated to make the temperature in the board racks 3-1 and 3-2 uniform. In this example, a large number of heat pipe unit groups 5 ′ including a small diameter heat pipe, a sheet heat pipe and the like are arranged along the burn-in board 6. Moreover, a large number of the heat pipe unit groups 5 ′ are arranged, for example, along the burn-in boards 6 of corresponding heights, between the pair of board racks 3-1 and 3-2 located before and after the flow of air. Has been established.

In this example, a pair of board racks 3-1,
The temperature of the air flowing between 3-2 can always be kept uniform as shown in the lower graph of FIG. Therefore, in the thermostat 1, the temperature of the air flowing between the pair of board racks 3-1 and 3-2 can be adjusted only by controlling the temperature of the air outside the furnace body 2.

In the third embodiment shown in FIG. 3, reference numeral 1 denotes a constant temperature in which a board rack 3-1, 3-2, 3-3 on which a plurality of burn-in boards on which a large number of devices are mounted is mounted inside the furnace body 2. It is a tank. An air circulation mechanism 4 composed of a sirocco fan or the like is attached to the constant temperature bath 1, and the air in the constant temperature bath 1 is circulated so that the board racks 3-1, 3-2, 3
The temperature is adjusted so as to make the temperature within -3 uniform. In this example, the heat pipe units 5-1 and 5-2 are arranged between the board racks 3-1, 3-2 and 3-3, respectively. And this heat pipe unit 5-
If 1, 5-2 are connected to each other, the temperature difference between the board racks 3-1, 3-2, 3-3 is eliminated, and the board racks 3-1, 3-2, 3-3 The temperature can always be kept constant.

FIG. 4 shows the temperature change at that time. That is, when the heat pipe units 5-1 and 5-2 are not provided, the board racks 3-1 → 3 as shown on the left side of FIG.
Although the temperature rises in the order of −2 → 3−3, by arranging the heat pipe units 5-1 and 5-2, accurate temperature adjustment can be performed as shown on the right side of FIG. It is.

The following is an example of the effects of the embodiment of the temperature distribution control device for a constant temperature bath. 1) The set temperature can be accurately maintained within a range of ± precision of a predetermined temperature distribution in the thermostat. 2) By using the current thermostat, it is possible to apply a load larger than the current load, and it is possible to cope with a device with a high load, and to increase the number of mounted devices even under the current condition. Will be able to Therefore, in the burn-in process performed at one time, the unit price for burn-in can be reduced. 3) The temperature distribution of the temperature distribution control device of the thermostatic bath can be automatically adjusted, the time of the temperature adjustment can be shortened, and the additional components such as the heat pipe unit can be compensated for by reducing the number of steps. 4) By adopting a unit configuration such as a heat pipe unit, a small-sized apparatus can be provided without increasing the size of a thermostat, and the unit cost of a device in a floor area can be reduced. 5) A plurality of board racks can be arranged in parallel, and a large-capacity burn-in test can be performed. 6) Since the temperature can be lowered more rapidly than at the time of temperature lowering, the time required for the burn-in process can be shortened.

[0025]

According to the present invention, by installing one end of the heat pipe in a portion of the thermostat where the temperature is desired to be lowered and the other end in a portion of the thermostat having a temperature lower than a predetermined temperature, A new thermostatic chamber temperature distribution that can effectively utilize the very fast heat transfer of the heat pipe and instantly cool down the atmosphere that has been heated up by the load of the above part test A control device can now be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a temperature distribution control device for a thermostatic bath according to the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the temperature distribution control device for a thermostatic bath of the present invention.

FIG. 3 is a schematic view showing still another embodiment.

FIG. 4 is a schematic diagram showing a temperature change under a test load in the embodiment of FIG. 3;

FIG. 5 is a schematic view showing an example of a conventional thermostat.

FIG. 6 is a schematic view showing an example of a conventional temperature distribution control device for a thermostatic bath.

FIG. 7 is a schematic view showing a main part thereof.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 constant temperature bath 2 furnace body 3-1, 3-2, 3-3 board rack 4 air circulation mechanism 5, 5-1, 5-2 heat pipe unit 5 'heat pipe unit group 6 burn-in board 11 constant temperature bath 12 sirocco fan Or pump 13 stepless automatic damper

Claims (2)

[Claims] 1. A thermostat in which a board rack in which a plurality of burn-in boards on which a number of devices are mounted is mounted is installed inside a heat pipe, one end of a heat pipe is installed in a portion where the temperature in the thermostat is to be lowered, and the other end is thermostated. A temperature distribution control device for a thermostatic bath, wherein the temperature distribution on each burn-in board in the thermostatic bath is made uniform by being installed in a portion of the bath having a temperature lower than a predetermined temperature. 2. A constant-temperature bath in which a board rack on which a plurality of burn-in boards on which a large number of devices are mounted is mounted is installed in a constant-temperature bath by installing a heat pipe along a flow direction of air in the constant-temperature bath. A temperature distribution control device for a thermostat, wherein the temperature on each burn-in board is made uniform.