Abstract:
A temperature control apparatus including 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 the intake side of the compressor by a predetermined quantity corresponding to an output of the temperature sensor.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the invention  
         [0002]     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.  
         [0003]     2. Description of the Related Art  
         [0004]     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.  
         [0005]     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  FIG. 1  of this document, executes temperature control of an electronic device  10  by keeping a thermal head  14  which combines a passage  36  in which refrigerant flows with an electric heater  30  in contact with the electronic device  10 . In a cooling system using the thermal head  14  having such a structure, heat is generated from the electronic device  10  and the heater  30  and this heat is absorbed by the cooling system. Therefore, when the amount of heat generated from the heater increases at the time of high temperature test, for example, the quantity of heat absorbed by refrigerant in the thermal head  14  increases so that the temperature of refrigerant supplied to a compressor  32  rises. As a result, the temperature in the compressor  32  is raised by heat generated when refrigerant is compressed and if this temperature exceeds a setting maximum temperature of the compressor  32 , a large thermal stress is applied to components inside the compressor  32 , so that the compressor  32  may be possibly damaged. Therefore, the quantity of heat generated from the heater  14  needs to be controlled strictly in order to prevent this serious phenomenon. This leads to increase in cost of the entire temperature control apparatus and a temperature controllable range between the lower limit and upper limit of the temperature control narrows, thereby limiting an electronic device which can be tested to particular ones.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     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.  
         [0007]     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. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0008]      FIG. 1  is a diagram schematically showing a structure of a cooling circuit of a temperature control apparatus of an electronic device including a compressor protection section according to an embodiment of the present invention;  
         [0009]      FIG. 2  is a structure diagram showing a concrete structure of the embodiment shown in  FIG. 1 ;  
         [0010]      FIG. 3  is a flow chart for explaining the temperature control operation of this embodiment; and  
         [0011]      FIG. 4  is a flow chart for explaining the protective operation of the cooling circuit according to this embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]     Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.  
         [0013]     Referring to  FIG. 1 , an evaporator  13  is provided within a temperature control head  12  with which an electronic device  11  as a testing object such as a semiconductor chip is kept in contact thermally. An electric heater described later is attached to this head  12  and a refrigerant passage  14   a  in which refrigerant flows through is formed within the evaporator  13 . The evaporator  13  is connected to a cooling circuit including a pipe  15  serving as a passage of refrigerant. An expansion valve  16  is connected to a refrigerant intake side of the evaporator  13  and an outlet side thereof is connected to a compressor  18  through an accumulator  17 . The pressure of refrigerant on the intake side of the expansion valve  16  is high while the pressure of refrigerant in the downstream of the evaporator  13  on the outlet is low.  
         [0014]     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 .  
         [0015]     The cooling system having such a structure includes a first temperature sensor T 1  for detecting the temperature in the temperature control head  12  and a second temperature sensor T 2  for detecting the temperature of refrigerant on the outlet side of the compressor  18 . It further includes a system controller (not shown in  FIG. 1 ) which executes for example PID control as a control portion for controlling the temperature of the electronic device by controlling the quantity of current in the electric heater and the quantity of refrigerant flowing through the refrigerant passage corresponding to an output of the first temperature sensor T 1  and controlling the quantity of bypassing of the condensed refrigerant on the intake side of the compressor  18  corresponding to an output of the second temperature sensor T 2 .  
         [0016]     The cooling system shown in  FIG. 1  may be provided with a drier DR, a high-pressure gauge G 1 , a high-pressure pressure switch P 1 , an electromagnetic valve S, a service port SP, a ball valve V, a low pressure gauge G 2 , a low-pressure pressure switch P 2  and the like corresponding to each purpose.  
         [0017]     Hereinafter, the concrete structure of the cooling system shown in  FIG. 1  will be described with reference to  FIG. 2 .  
         [0018]     The same reference numerals are attached to components corresponding to those of  FIG. 1 . The temperature control head  12  is constructed by combining the evaporator  13  having plural refrigerant passages  14   a  and an electric heater  14   b . A semiconductor chip  11  is bonded to the bottom face of the temperature control head  12  through heat conductive films  12   a ,  12   b . A plurality of solder ball terminals  11   a  are formed on the bottom face of the semiconductor chip  11  and the semiconductor chip is connected to a connecting terminal provided on a socket  10   s  through this solder ball terminal  11   a  and further connected to an outside test unit (not shown) so as to perform a predetermined test. A probe T 1 P of the temperature sensor T 1  is kept in contact with the semiconductor chip  11  and a detection output of the temperature sensor T 1  is supplied to a system controller  31  for PID control. The electric heater  14   b  provided on the temperature control head  12  is driven by a heater driver  14   b D under a control of the system controller  31 .  
         [0019]     The plurality of refrigerant passages  14   a  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 T 2 P of another temperature sensor T 2  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 T 2  is supplied to the system controller  31 .  
         [0020]     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  15 A and a second branch pipe  15 B in succession. These first and second branch pipes  15 A,  15 B communicate with the refrigerant pipe  15  connected to the intake side of the accumulator  17  through electromagnetic valves  15 AV,  15 BV. These electromagnetic valves  15 AV,  15 BV are opened/closed by the system controller  31  under each predetermined condition, which will be described later.  
         [0021]     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 .  
         [0022]     Next, the operation of the cooling system having such a structure will be described with reference to  FIGS. 3, 4 . If the performance test of the electronic device  11  is carried out at a predetermined temperature higher than the room temperature, a user sets up a lower limit value STL of a setting temperature range in the system controller  31 . In this case, a temperature DT of the electronic device  11  is equal to the room temperature and a temperature detected by the temperature sensor T 1  through the probe T 1 P is low when the temperature control is started. Thus, a result of determination turns to YES in initial step S 1  of  FIG. 3  (DT&lt;STL?) and the control proceeds to step S 2 . As a consequence, an instruction of “CLOSE” is sent from the system controller  31  to the electromagnetic expansion valve  16  so that no refrigerant flows to the evaporator  13  and the valve  15 BV turns to “OPEN” to allow refrigerant to pass through the bypass passage  15 B. At the same time, the heater driver  14   b B is driven to supply electricity to the electric heater  14   b , so that the electronic device  11  is heated without being cooled.  
         [0023]     When the temperature DT of the electronic device  11  exceeds the lower setting temperature STL, a result of determination in step S 1  is NO and then, the control proceeds to step S 3 . Here, whether or not the temperature DT of the device  11  detected by the temperature sensor T 1  exceeds the upper limit value STH of the test temperature range (DT&gt;STH?) is determined. If the result is NO, the control proceeds to step S 4 , 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  15 BV turns to “OPEN” so that refrigerant continues to pass through the bypass passage  15 B. At the same time, the drive condition of the heater driver  14   b D is released so that the electric heater  14   b  turns to non-conductive state, thereby stopping heating of the electronic device  11 .  
         [0024]     On the other hand, if the temperature of the electronic device  11  rises too much (DT&gt;STH?) in the condition of step S 3  (YES in step S 3 ), 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  15 BV turns to “CLOSE” so that refrigerant is blocked from passing the bypass passage  15 B. At this time, the drive condition of the heat driver  14   b D is released so that the electric heater  14   b  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&lt;STL, the control is YES in step S 1  so that the same temperature control action is maintained between the lower and upper temperature setting ranges STL and STH.  
         [0025]     As for the control of the electric heater  14   b  and the expansion valve  16 , software control by a computer can be executed instead of hardware control by the system controller  31  by PID.  
         [0026]     Next, the operation of preventing the compressor  18  from being destroyed by overheat will be described with reference to  FIG. 4 . When the temperature control of the electronic device  11  is carried out with reference to  FIG. 3 , the refrigerant temperature RT in the pipe  15  on the outlet side of the compressor  18  is detected by the probe T 2 P of the temperature sensor T 2  and sent to the system controller  31 . A refrigerant upper limit temperature PT is set up on the system controller  31  in order to protect the compressor  18  and whether or not this refrigerant temperature RT is over the set refrigerant upper limit temperature PT is determined in step S 11 .  
         [0027]     When the refrigerant temperature RT is lower than the refrigerant upper limit temperature PT, the result is NO and the control proceeds to step S 12 , in which the electromagnetic valve  15 AV on the refrigerant bypass passage  15 A is kept in “CLOSE”. At this time, the electromagnetic valve  15 BV on the other refrigerant bypass passage  15 B can be opened or closed corresponding to the temperature DT of the electronic device  11  as described in  FIG. 3 .  
         [0028]     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 S 11  is YES and the control proceeds to step S 13 . The electromagnetic valve  15 AV 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  15 A. 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.  
         [0029]     Drop of the refrigerant temperature RT on the outlet side of the compressor  18  by opening of the electromagnetic valve  15 AV is continued while the result is NO in step S 14  (RT&lt;PT?).  
         [0030]     If the result is YES in step S 14  (RT&lt;PT?), the control proceeds to step S 12 , in which the electromagnetic valve  15 AV 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  15 AV can be carried out without affecting the temperature control operation of the electronic device  11  so much.  
         [0031]     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  14   b  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  14   b  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.  
         [0032]     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.