Patent Application
20070240870
1. Field of the invention
The present invention relates to a temperature control apparatus, and particularly to a temperature control apparatus for controlling the temperature of an electronic device at the time of test.
2. Description of the Related Art
Prior to shipment, performance test of an electronic device, for example, a semiconductor chip needs to be carried out at a room temperature or a higher temperature or a lower temperature. When the performance test of a semiconductor chip is carried out at a room temperature under a rated current, heat is generated inside the semiconductor chip by this current so that the temperature of the chip is raised more than the room temperature. Thus, the semiconductor chip needs to be cooled appropriately to maintain the temperature at the room temperature. When the semiconductor chip is heated with a heater or the like in case of high temperature test, it needs to be cooled appropriately in order to keep the temperature from being raised more than a setting temperature. These cases of cooling are carried out with a temperature setting head loaded with a semiconductor chip connected to a predetermined cooling system.
As a conventional temperature control apparatus, a temperature control apparatus disclosed in, for example, U.S. Pat. No. 6,668,570 has been well known. This conventional apparatus, as shown in
According to one aspect of the present invention, there is provided a temperature control apparatus comprising: a temperature control head kept in contact with an electronic device as a testing object thermally; an electric heater attached to the temperature control head; a refrigerant passage formed within the temperature control head so as to run through inside thereof; a compressor which compresses refrigerant coming out of the temperature control head; a temperature sensor which detects a temperature of refrigerant on an outlet side of the compressor; a condenser which condenses refrigerant coming out of the compressor; a returning portion which returns refrigerant condensed by the condenser to the temperature control head; and a control portion which bypasses the condensed refrigerant to an intake side of the compressor by a predetermined quantity corresponding to an output of the temperature sensor.
According to another aspect of the present invention, there is provided a temperature control apparatus comprising: a temperature control head kept in contact with an electronic device as a testing object thermally; an electric heater attached to the temperature control head; a refrigerant passage formed within the temperature control head so as to run through inside thereof; a first temperature sensor which detects a temperature of the electronic device; a compressor which compresses refrigerant coming out of the temperature control head; a second temperature sensor which detects a temperature of refrigerant on the outlet side of the compressor; a condenser which condenses refrigerant coming out of the compressor; a returning portion which returns refrigerant condensed by the condenser to the temperature control head; and a control portion which controls the temperature of the electronic device by controlling the quantity of electricity supplied to the electric heater and the quantity of refrigerant flowing through the refrigerant passage corresponding to an output of the first temperature sensor and controls the quantity of the condensed refrigerant bypassed to the intake side of the compressor corresponding to an output of the second temperature sensor.
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
Referring to
After passing the temperature control head 12, low pressure refrigerant is collected in the accumulator 17 and then fed to and compressed in the compressor 18. High pressure refrigerant compressed by this compressor 18 is condensed by a condenser 19 on a next step using a fan 20 and condensed refrigerant is returned to the expansion valve 16 through the pipe 15 and further returned to the accumulator 17 through an electromagnetic valve 21 and a capillary tube 22.
The cooling system having such a structure includes a first temperature sensor T1 for detecting the temperature in the temperature control head 12 and a second temperature sensor T2 for detecting the temperature of refrigerant on the outlet side of the compressor 18. It further includes a system controller (not shown in
The cooling system shown in
Hereinafter, the concrete structure of the cooling system shown in
The same reference numerals are attached to components corresponding to those of
The plurality of refrigerant passages 14a formed within the evaporator 13 are connected to the refrigerant pipe 15 on the intake side and the refrigerant pipe 15 on the outlet side. The refrigerant pipe 15 connected to the outlet side of the temperature control head 12 is connected to the compressor 18 through the accumulator 17. A probe T2P of another temperature sensor T2 is installed on the refrigerant pipe 15 on the outlet side of this compressor 18 so as to detect the temperature of refrigerant on the outlet side of the compressor 18. A detection output of this temperature sensor T2 is supplied to the system controller 31.
The refrigerant pipe 15 connected to the outlet side of the compressor 18 is coupled with the intake side of the condenser 19. This condenser 19 is a radiator and heat of refrigerant is radiated by blowing air to the radiator 19 with the fan 20 to condense gaseous refrigerant to liquid refrigerant. The refrigerant pipe 15 connected to the outlet side of the condenser 19 is branched to a first branch pipe 15A and a second branch pipe 15B in succession. These first and second branch pipes 15A, 15B communicate with the refrigerant pipe 15 connected to the intake side of the accumulator 17 through electromagnetic valves 15AV, 15BV. These electromagnetic valves 15AV, 15BV are opened/closed by the system controller 31 under each predetermined condition, which will be described later.
The refrigerant pipe 15 connected to the outlet side of the condenser 19 is connected to the intake side of the electronic expansion valve 16 provided on the intake side of evaporator 13.
Next, the operation of the cooling system having such a structure will be described with reference to
When the temperature DT of the electronic device 11 exceeds the lower setting temperature STL, a result of determination in step S1 is NO and then, the control proceeds to step S3. Here, whether or not the temperature DT of the device 11 detected by the temperature sensor T1 exceeds the upper limit value STH of the test temperature range (DT>STH?) is determined. If the result is NO, the control proceeds to step S4, in which an instruction of “CLOSE” continues to be given to the electromagnetic expansion valve 16 from the system controller 31 and a condition in which refrigerator is blocked from flowing to the evaporator 13 is maintained and the valve 15BV turns to “OPEN” so that refrigerant continues to pass through the bypass passage 15B. At the same time, the drive condition of the heater driver 14bD is released so that the electric heater 14b turns to non-conductive state, thereby stopping heating of the electronic device 11.
On the other hand, if the temperature of the electronic device 11 rises too much (DT>STH?) in the condition of step S3 (YES in step S3), the control proceeds to step 5, in which an instruction of “OPEN” is supplied from the system controller 31 to the electromagnetic expansion valve 16 and refrigerant flows into the evaporator 13. At the same time, the valve 15BV turns to “CLOSE” so that refrigerant is blocked from passing the bypass passage 15B. At this time, the drive condition of the heat driver 14bD is released so that the electric heater 14b turns to non-conductive state and the heating of the electronic device 11 is continuously halted. As a result, the electronic device 11 is cooled by absorption of heat when refrigerant flowing through the evaporator 13 is evaporated and the temperature DT falls to the lower setting temperature STL. When DT<STL, the control is YES in step S1 so that the same temperature control action is maintained between the lower and upper temperature setting ranges STL and STH.
As for the control of the electric heater 14b and the expansion valve 16, software control by a computer can be executed instead of hardware control by the system controller 31 by PID.
Next, the operation of preventing the compressor 18 from being destroyed by overheat will be described with reference to
When the refrigerant temperature RT is lower than the refrigerant upper limit temperature PT, the result is NO and the control proceeds to step S12, in which the electromagnetic valve 15AV on the refrigerant bypass passage 15A is kept in “CLOSE”. At this time, the electromagnetic valve 15BV on the other refrigerant bypass passage 15B can be opened or closed corresponding to the temperature DT of the electronic device 11 as described in
When the refrigerant temperature RT on the outlet side of the compressor 18 is higher than the upper limit temperature PT, a determination result in step S11 is YES and the control proceeds to step S13. The electromagnetic valve 15AV is opened by a control of the system controller 31 and refrigerant condensed and cooled by the condenser 19 flows into the accumulator 17 through the bypass passage 15A. As a consequence, the temperature RT of refrigerant supplied from the accumulator 17 to the compressor 18 drops thereby preventing the compressor 18 from being overheated.
Drop of the refrigerant temperature RT on the outlet side of the compressor 18 by opening of the electromagnetic valve 15AV is continued while the result is NO in step S14 (RT<PT?).
If the result is YES in step S14 (RT<PT?), the control proceeds to step S12, in which the electromagnetic valve 15AV is closed under a control of the system controller 31 so that bypass refrigerant flowing into the accumulator 17 is vanished. As a consequence, the refrigerant temperature RT on the outlet side of the compressor 18 begins to rise again. Control of the refrigerant temperature on the outlet side of the compressor 18 by opening/closing of the electromagnetic valve 15AV can be carried out without affecting the temperature control operation of the electronic device 11 so much.
According to this embodiment, as described above, this temperature does not exceed the setting maximum temperature of the compressor 18 even if the quantity of heat generated from the heater 14b increases in a high temperature test so that the temperature of refrigerant supplied to the compressor 18 rises. Thus, components in the compressor 18 are protected from a large thermal stress, thereby protecting the compressor 18 from a damage. Therefore, the quantity of heat generated from the heater 14b does not need to be carried out strictly, cost of the entire temperature control apparatus can be suppressed to a low level, a temperature controllable range between the lower limit and upper limit of the temperature control can be secured and an electronic device which can be tested is not restricted to any particular type.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
