Abstract:
A device and method for controlling the temperature of a semiconductor module in which the semiconductor module is sandwiched by a first supporting unit and a second supporting unit. An area of the second supporting unit with which the semiconductor module comes into contact is shielded from heat of external ambient atmosphere, and has a temperature sensor provided thereat. The temperature of the first supporting unit is controlled so that the temperature of this area becomes equal to a predetermined temperature. The amount of heat moving from the heat-shielded area to the semiconductor module is small, so that the difference between the temperatures in the region extending from the heat-shielded area and the semiconductor module is small. The first and second supporting units may be separately controlled at different predetermined temperatures. By this, changes in the temperature of the semiconductor module caused by changes in outside air temperature are reduced. The invention aims at making the difference between the temperature of the semiconductor module and a predetermined temperature small when controlling the temperature of the semiconductor module by bringing it into contact with the supporting units whose temperatures have been controlled.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a device for controlling the temperature of a semiconductor module and a method of controlling the temperature of a semiconductor module. More particularly, the present invention relates to a device and a method for precisely controlling the temperature of a semiconductor module, which is a test sample on which an environmental temperature test is performed, to a test temperature.  
           [0003]    A semiconductor module, such as an optical module having an optical semiconductor element, such as a laser, mounted therein is widely used as a key component of a high-speed communication network as typified by the internet. Among semiconductor modules, the demand for a small cooler-less module for intermediate-distance optical communication is increasing.  
           [0004]    Such semiconductor modules are often used in locations where high reliability is required of them as in a submarine repeater, or in locations where the temperature environment is severe such as outdoors, so that they are subjected to strict environmental temperature tests to guarantee their reliability.  
           [0005]    In environmental temperature tests, the temperatures of semiconductor modules are changed in accordance with a predetermined temperature sequence, during which optical input/output characteristics are observed. Based on the temperature dependencies of the observed semiconductor modules, it is determined whether these observed semiconductor modules are good or defective modules. Therefore, in order to precisely measure the temperature dependencies, it is necessary to precisely control the temperatures of the semiconductor modules.  
           [0006]    2. Description of the Related Art  
           [0007]    Hitherto, in an environmental temperature test of a semiconductor module, such as an optical module, the temperature of the semiconductor module is kept at the test temperature by placing the semiconductor module on an temperature equalizing block controlled to a test temperature. Hereunder, a related test device will be described.  
           [0008]    [0008]FIG. 1 is a side view of a related device used for an environmental temperature test of a semiconductor module. Referring to FIG. 1, in the related test device, a heat exchanger  53 , a Peltier element  51 , and an temperature equalizing block  52  are placed upon each other in that order on a device base  50  in contact with each other. The Peltier element  51  varies the temperature of the temperature equalizing block  52  by absorbing or discharging heat from the temperature equalizing block  52  which is placed in contact with the top surface of the Peltier element  51 . The temperature of the temperature equalizing block  52  is detected by a platinum resistance temperature sensor  54  placed inside a hollow near the top surface of the temperature equalizing block  52 . The Peltier element is driven so that the detected temperature of the temperature equalizing block  52  is equal to the test temperature, that is, an environmental temperature specified in a test specification.  
           [0009]    In a semiconductor module  10 , a semiconductor laser element, a built-in Peltier element for controlling the temperature of the semiconductor laser element, and an optical part (none of which are shown) are incorporated in a package  13  including a heat-dissipating plate  12 , disposed at the lower portion of the semiconductor module  10 , and a cover  11  that covers the heat-dissipating plate  12 . In the semiconductor module  10 , which is a test sample on which an environmental temperature test is conducted, the bottom surface of the heat-dissipating plate  12  is placed in close contact with the top surface of the temperature equalizing block  52 , so that, by conduction of heat from the top surface of the temperature equalizing block  52 , the temperature of the semiconductor module  10  is kept equal to the temperature of the temperature equalizing block  52 . With the temperatures being kept equal to each other, characteristics of the semiconductor module, such as the light input/output characteristics, are measured.  
           [0010]    In the above-described related environmental temperature test device, the temperature of the temperature equalizing block  52  is controlled at a predetermined temperature specified in the test specification. By placing the semiconductor module  10 , which is a test sample, on the temperature equalizing block  52 , the temperature of the semiconductor module  10  is caused to reach the predetermined temperature of the temperature equalizing block.  
           [0011]    However, since the semiconductor module  10  is only placed on the temperature equalizing block  52 , heat resistance between the semiconductor module  10  and the temperature equalizing block  52  tends to become large due to contact failure. Considering heat dissipation, the top surface of the semiconductor module  10  (that is, the surface opposite to the surface that contacts the temperature equalizing block  52 ) is ordinarily designed so that the heat resistance with the ambient atmosphere is small. As a result, a large amount of heat dissipation from the top surface of the semiconductor module  10  causes a large temperature difference to occur due to the heat resistance between the temperature equalizing block  52  and the semiconductor module  10 . Therefore, the temperature of the semiconductor module  10  is different by that amount of temperature difference from the predetermined temperature being specified in the test specification. In an ordinary specification of the environmental temperature test, the test temperature is set at the surface temperature of the semiconductor module  10 . In such a case, the difference between the temperatures of the temperature equalizing block  52  and the semiconductor module  10  cannot be ignored because it causes a reduction in the accuracy of the test temperature of the environmental temperature test.  
           [0012]    To prevent such a temperature difference, an attempt has been made to carry out a method of monitoring the temperature of the semiconductor module  10  using a temperature sensor, such as a thermistor, which is attached to a surface of the semiconductor module  10 . However, in this method, the temperature distribution in the semiconductor module varies due to a considerable change in the heat transfer coefficient at the portion to which the temperature sensor is attached, consequently the temperature of the semiconductor module  10  cannot be precisely measured.  
           [0013]    In addition, the semiconductor module  10  incorporates elements, including the semiconductor laser element and the Peltier element, which generate or absorb a large amount of heat. The generation and absorption of heat by these elements change the temperature distribution of a portion of the test device that contacts the semiconductor module  10 , such as the temperature distribution near the top surface of the temperature equalizing block  52 . The temperature sensor  54  of the temperature equalizing block  52  is not necessarily provided at a location where it can precisely detect this temperature distribution. Therefore, it becomes more difficult to precisely measure and control the surface temperature of the semiconductor module.  
           [0014]    Another problem with the above-described related environmental temperature test device is that there is difficulty in controlling the temperature of the semiconductor module near room temperature.  
           [0015]    Environmental temperature tests usually need to be carried out at ordinary temperatures. This ordinary temperature is generally specified as a temperature near 25 degrees, so that there are cases where there is very little difference between the ordinary temperature and the room temperature. In this case, the difference between the temperature of the temperature equalizing block  52  kept at ordinary temperature and the temperature of the ambient atmosphere at room temperature is small, consequently it is difficult to control the temperature. In addition, changes in the temperature of the ambient atmosphere surrounding the semiconductor package immediately changes the temperature of the surface of the semiconductor package. Accordingly, it is very difficult to stably maintain the temperature of the semiconductor package at an ordinary temperature near a room temperature.  
           [0016]    As described above, in the related device for controlling the temperature of a semiconductor module used in the environmental temperature test, by placing the semiconductor module on the temperature equalizing block controlled at the test temperature, the temperature of the semiconductor module is caused to reach the test temperature. However, there is a problem that the temperature of the semiconductor module is difficult to be controlled precisely, since a temperature difference occurs due to heat resistance between the temperature equalizing block and the semiconductor module.  
           [0017]    When the control temperature is near room temperature, it is difficult to control the temperature of the semiconductor module, since the difference between the temperatures of the semiconductor module and the temperature of the ambient atmosphere is small. In addition, there is another problem that a fluctuation in the room temperature directly leads to large change of the temperature of the semiconductor module.  
         SUMMARY OF THE INVENTION  
         [0018]    It is an object of the present invention to provide a device and method for controlling temperature, which make it possible to precisely control the temperature of a semiconductor module to a predetermined temperature.  
           [0019]    It is another object of the present invention to provide a device and method for controlling the temperature of a semiconductor module, which make it possible to precisely control the temperature of the semiconductor module near ordinary temperature and which are unaffected by changes in the temperature of ambient atmosphere.  
           [0020]    [0020]FIG. 2 is a side view of an assembly of a first embodiment of the present invention, showing the structure of supporting units of a semiconductor module. FIG. 3 is a sectional view of the first embodiment of the present invention, showing a state in which the semiconductor module, mounted to a socket, is supported by the supporting units.  
           [0021]    Referring to FIGS. 2 and 3, in a first structure of the present invention, a first heat transfer surface  25  of a first supporting unit  20  and a second heat transfer surface  31  of a second supporting unit  30  contact different portions, such as the top and bottom surfaces, of a semiconductor module  10 , respectively. Through both of the heat transfer surfaces  25  and  31 , heat is exchanged between the first and second supporting units  20  and  30  and the semiconductor module  10 , respectively.  
           [0022]    The second supporting unit  30  further includes a temperature sensor  34  and a heat insulating section  33 . The heat insulating section  33  is provided near an area including the second heat transfer surface  31  and the temperature sensor  34 , and limits heat flow to that from only the second heat transfer surface  31  with regard to heat flowing into and out of this area. This limiting operation is not limited to the case where, with regard to the flowing-in and flowing-out of heat of the area, heat flow from portions other than the second heat transfer surface is nearly blocked. For example, this operation may be more or less limited heat flow into and out of this area from the portions other than the second heat transfer surface.  
           [0023]    In the first structure, the temperature of the first supporting unit  20  is cotrolled so that the temperature measured by the temperature sensor  34 , which measures the temperature of the area of the second supporting unit  30  insulated by the heat insulating section  33 , is equal to a predetermined temperature which is a control target temperature. Here, the temperature of the first supporting unit  20  is not controlled so that it equals a previously determined temperature. The temperature of the second supporting unit  30  measured by the temperature sensor  34  is controlled so that it equals the target temperature.  
           [0024]    When the temperature of the first supporting unit  20  is lower than that of the second supporting unit  30 , heat flows into the semiconductor module  10  from the second heat transfer surface  31  through a portion of the semiconductor module  10  that contacts the second heat transfer surface  31 . From another portion of the semiconductor module  10 , the heat flows into the first supporting unit  20  through the first heat transfer surface  25  that contacts this another portion. On the other hand, when the temperature of the first supporting unit  20  is higher than that of the second supporting unit  30 , heat flows in the opposite direction. Therefore, based on the heat resistances between the first and second heat transfer surfaces  25  and  31  and the semiconductor module  10 , a temperature difference occurs between the first and second supporting units  20  and  30  and the semiconductor module  10  in proportion to the amount of heat flow through these heat transfer surfaces  25  and  31 .  
           [0025]    In the above-described first structure of the present invention, the area of the second supporting unit  30 , in which the temperature sensor  34  and the second heat transfer surface  31  are disposed, is shielded thermally by the heat insulating section  33 . Therefore the amount of heat flowing into and out of this area is small. The amount of heat flowing through the second heat transfer surface  31  is equal to the sum of the amount of heat required to make the temperature of this area equal to the target temperature and the amount of heat flowing into and out of this area through the periphery of this area except the second heat transfer surface  31 . In the structure, since the amount of heat flowing into and out of this area through the periphery of this area except the second heat transfer surface  31  is small, the amount of heat flowing through the second heat transfer surface  31  is small. As a result the difference between the temperature of the second supporting unit  30  (more exactly the area including therein the second heat transfer surface  31  and the temperature sensor  34 ) and the temperature of the semiconductor module  10  is small. Therefore, the temperature of the semiconductor module  10  can be made nearly equal to the temperature of the second supporting unit  30  with a slight temperature difference. The temperature of the second supporting unit  30  is measured by the temperature sensor  34  and is controlled based on the measurement result, and is, thus, maintained precisely at the predetermined temperature. Consequently, the temperature of the semiconductor module  10  is controlled so as to be almost equal to the predetermined temperature with a slight temperature difference.  
           [0026]    When heat is generated from the inside of the semiconductor module  10 , the generated heat raises the temperature of the semiconductor module  10  and then raises a temperature of a portion of the second supporting unit  30  near the second heat transfer surface  31 . This temperature rise is immediately detected by the temperature sensor  34  disposed near the second heat transfer surface  31  and is corrected. This correction is achieved by increasing the amount of heat flowing into the first supporting unit  20  from the semiconductor module  10  through the first heat transfer surface  25  by lowering the temperature of the first supporting unit  20 . Therefore, the generated heat in the semiconductor module  10  is absorbed mainly as a result of an increase or decrease in the temperature difference between the first heat transfer surface  25  and the semiconductor module  10 , so that the amount of heat flowing through the second heat transfer surface  31  does not vary significantly. For this reason, the difference between the temperatures of the second supporting unit  30  and the semiconductor module  10  varies little, thereby making it possible to precisely control the temperature of the semiconductor module  10  that generates heat.  
           [0027]    The area where heat is blocked may be limited to a small portion of the second supporting unit  30  so as to reduce the heat capacity of this area. By this limitation it is possible to sensitively detect a change of the temperature of the semiconductor module  10 . In addition, the heat insulating section  33 , provided at the second supporting unit  30 , increases the heat resistance between the second supporting unit  30  and the external environment, such as indoor ambient atmosphere. Therefore, the change of the temperature of the external environment does not substantially influence on the controlling operation of the temperature of the semiconductor module  10 .  
           [0028]    [0028]FIG. 5 is a sectional view of an assembly of a second embodiment of the present invention, showing supporting units of a semiconductor module.  
           [0029]    Referring to FIG. 5, a temperature regulator  36  for raising and lowering the temperature of a second supporting unit  30  may be provided in place of the heat insulating section  33  of the above-described first structure in the present invention. The temperature regulator  36  is driven so that the temperature of the second supporting unit  30  is maintained nearly at a control target temperature or becomes at least close to the control a target temperature. This driving operation may be performed to control the temperature of a portion of the second supporting unit  30  other than the area including the temperature sensor  34  at a previously determined temperature, or to generate or absorb heat in the second supporting unit  30  according to a predetermined sequence. In this structure, since the difference between the temperatures of the area including the temperature sensor  34  and portions near this area is small, the amount of heat flowing into and out of the area is small, thereby making it possible to provide similar advantages to those provided when the heat insulating section  33  is disposed.  
           [0030]    Referring to FIG. 5, in a second structure of the present invention, similarly to the already mentioned first structure, a first heat transfer surface  25  disposed on a first supporting unit  20  and a second heat transfer surface  31  disposed on a second supporting unit  30  contact different portions of a semiconductor module  10 , respectively, so that heat is exchanged between the supporting units  20  and  30  and the semiconductor module  10  through both of the heat transfer surfaces  25  and  31 .  
           [0031]    In the second structure, the temperatures of the first and second supporting units  20  and  30  are each controlled at different predetermined temperatures. Heat flows through the semiconductor module  10  based on the temperature difference between the first and second supporting units  20  and  30 . During the temperature test, the temperatures of both of the supporting units  20  and  30  are maintained at certain temperatures so that the heat flow is steady. When the heat flow is steady, the amount of heat flowing through both of the heat transfer surfaces  25  and  31  is constant. Therefore, the difference between the temperatures of the semiconductor module  10  and both supporting units  20  and  30  does not change with time, and, thus, becomes constant. As a result, the temperature of the semiconductor module  10  is maintained at a constant temperature intermediate between those of the first and second supporting units  20  and  30 . For the case where the predetermined temperatures of the supporting units  20  and  30  change in a quasi-steady manner in accordance with the temperature sequence, a similar argument can be made.  
           [0032]    The temperature of the semiconductor module  10  in the second structure is determined by the temperatures of the first and second supporting units  20  and  30  and the heat resistances between the semiconductor module  10  and the first and second heat transfer surfaces  25  and  31 . The heat resistances between the semiconductor module  10  and the first and second heat transfer surfaces  25  and  31  is constant after the semiconductor module  10  has been mounted to the supporting units  20  and  30 , so that it does not change with the passage of time and with changes of the temperatures of the supporting units  20  and  30  with. Therefore, when the heat resistances of the two heat transfer surfaces  25  and  31  or the ratio between the heat resistances is previously known, it is possible to set the temperatures of the first and second supporting units  20  and  30  so that the temperature of the semiconductor module  10  is set at a predetermined temperature. In other words, the temperature of the semiconductor module  10  can be made exactly equal to the predetermined temperature. The heat resistances can be known by, for example, measuring the temperature of the semiconductor module  10 , and comparing it with the temperatures of the supporting units  20  and  30 .  
           [0033]    The temperatures of the first and second supporting units  20  and  30  that can maintain the temperature of the semiconductor module  10  at the predetermined temperature are not limited to one value set. For example, the temperature of the semiconductor module  10  can be maintained at the predetermined temperature by making the temperature of one of the supporting units higher and that of the other supporting unit lower. Therefore, it is possible to control the temperature of the semiconductor module  10  to the predetermined temperature under the condition of large temperature difference existing between the first and second supporting units  20  and  30 . By making the difference between the temperatures of the supporting units  20  and  30  large as mentioned above, the amount of heat flowing through the heat transfer surfaces  25  and  31  is made large, so that stability of the temperature control can be enhanced. When the predetermined temperature is close to room temperature, since the difference between room temperature and the temperatures of the supporting units  20  and  30  to be subjected to temperature control can be made large, the temperatures of the supporting units  20  and  30  is also stably controlled. When the amount of heat flowing through the heat transfer surfaces  25  and  31  is large, the temperature of the semiconductor module  10  is always precisely controlled to the predetermined temperature in accordance with the ratio between the heat resistances regardless of the temperature difference between the semiconductor module  10  and the heat transfer surfaces  25  and  31 .  
           [0034]    In the above-described second structure of the present invention, when the amount of heat generated in the semiconductor module  10  is constant, the temperature of the semiconductor module  10  can be exactly controlled to the predetermined temperature by considering that the temperature of the semiconductor module  10  increases by the corresponding rise in temperature of the semiconductor module  10  due to the heat generation. Even when the amount of generated heat changes (for example, even when the amount of generated heat depends upon the temperature of the semiconductor module  10 ), if the rise in temperature by the heat generation can be known, it is possible to know the exact temperature by correction. However, when the amount of generated heat changes, it is usually difficult to know the amount of rise in temperature. In such a case, the large temperature difference between the supporting units  20  and  30  increases the amount of heat flowing through the heat transfer surfaces  25  and  31 , so that the ratio of the change of the heat flow amount due to the heat generation in the semiconductor module  10  is made small. As result, it is possible to reduce the influence of the heat generation in the semiconductor module.  
           [0035]    A third structure of the present invention relates to a method of controlling temperature by heat exchange with a semiconductor module through a plurality of heat transfer surfaces. The method of controlling temperature relates to the above-described second structure of the present invention corresponds to the case where two heat transfer surfaces are used in the third structure.  
           [0036]    In the third structure, the temperatures of the plurality of heat transfer surfaces are controlled at predetermined temperatures respectively, and the temperature of at least one of the plurality of heat transfer surfaces is controlled at a temperature that is different from the temperatures of the other heat transfer surfaces. Therefore, as in the description of the second structure of the present invention, temperature control can be carried out so that the temperature of the semiconductor module, which contacts these heat transfer surfaces, is equal to a predetermined temperature. The third structure provides operations and advantages that are substantially the same as those provided by the second structure of the invention, such as that stable temperature control is achieved, and that the effects of, for example, room temperature are small.  
           [0037]    In the above-described first and second structures, the semiconductor module  10  may be interposed between the heat transfer surfaces  25  and  31  disposed so as to oppose each other. By interposing the semiconductor module  10 , the heat transfer surfaces  25  and  31  can be pressed against the semiconductor module  10 , so that heat resistances therebetween can be made small.  
           [0038]    In the first and second structures, by using a specially constructed supporting unit and a socket, it is possible to control the temperature of the semiconductor module with the semiconductor module being mounted to the socket. Hereunder, a description of the supporting unit and the socket will be given.  
           [0039]    With reference to FIGS. 4A and 4B, a socket  40  for mounting the semiconductor module  10  thereto has a through hole  42  formed in the center of a socket base  41 . A head section  32  is provided so as to protrude from the supporting unit, with an end of the head section  32  being a heat transfer surface  31 . The head section  32  is fitted through the through hole  42 , so that the heat transfer surface  31  protrudes from the socket base  41 . The protruding heat transfer surface  31  contacts the surface of the semiconductor module  10  mounted to the socket base  41 . By using the supporting unit and the socket, the temperature controlling devices in accordance with the already described first and second structures of the present invention can be applied with the semiconductor module being mounted to the socket. The head section  32  that is fitted through the through hole  42  of the socket  40  may be provided in either of the first and second supporting units  20  and  30 .  
           [0040]    In a fourth structure of the present invention, a first unit for controlling the temperature of a semiconductor module and a second unit for measuring the temperature of the semiconductor module are disposed apart from each other as separate units. For the semiconductor module, a portion suitable for controlling temperature and a portion suitable for measuring temperature are sometimes different. In this structure, these portions can be separately thermally connected.  
           [0041]    Since the inside of the semiconductor module is not homogeneous, even if an attempt is made to change the temperature of the semiconductor module by desired temperature, the rate of changes in temperature of the semiconductor module (changes in temperature per unit time) is sometimes different from the rate of changes in temperature of the first unit for controlling temperature. According to this structure, the temperature of the first unit for controlling temperature is not measured. The second unit that thermally contacts the semiconductor module separately of the first unit is used to measure the temperature of the semiconductor module, so that the rate of changes in temperature of the semiconductor package can be more precisely obtained than that when the temperature of the first unit is measured. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0042]    [0042]FIG. 1 is a side view of a related example.  
         [0043]    [0043]FIG. 2 is a side view of an assembly of a first embodiment of the present invention.  
         [0044]    [0044]FIG. 3 is a sectional view of the first embodiment of the present invention.  
         [0045]    [0045]FIGS. 4A to  4 C are perspective views of the first embodiment of the present invention.  
         [0046]    [0046]FIG. 5 is a sectional view of an assembly of a second embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0047]    The first embodiment of the present invention relates to a device for controlling the temperature of a semiconductor module. The device is related to the first structure of the present invention used in an environmental temperature test for an optical module.  
         [0048]    First, a description of a semiconductor module, which is a test sample on which the environmental temperature test is conducted, will be described. Referring to FIG. 2, a semiconductor module  10  in the embodiment is an optical module incorporating a semiconductor laser element (not shown), and includes a package  13 . The package  13  includes a heat-dissipating plate  12 , which forms the bottom surface of the optical module and which serves as a mounting attachment, and a cover  11  for covering the top surface of the heat-dissipating plate  12  as a box does. Inside the package  13 , an optical part and a Peltier element for controlling the temperature of the laser element, neither of which is shown, are provided on the heat-dissipating plate  12 , with the semiconductor laser element (not shown) being placed on the Peltier element. DIP (dual in-line package) lead pins  15  are provided in a row on both side surfaces of the package  13 , and an optical fiber  14  is drawn out from an end of the package  13 .  
         [0049]    The semiconductor module  10  is subjected to the environmental temperature test by being mounted to the socket  40  serving as a jig of the temperature controlling device. Referring to FIG. 4A, two rows of pin holes  45  for inserting the pins  15  of the semiconductor module  10  therethrough are formed, one row each at the left and right sides of the top surface of the socket base  41 . Pads  43  are provided on both side surfaces of the socket base  41  in correspondence with each of the pin holes  45 . In FIG. 4A, some of the pads  43  are not shown. Contactors (not shown) for electrical connection with the pins  15  are provided at the pin holes  45 . Using an internal wiring, the contactors are electrically connected to their corresponding pads  45 . The pads  43  are used to electrically connect the semiconductor module  10  and devices like measuring devices during the environmental temperature test.  
         [0050]    In the socket  40 , a through hole  42  is formed in the central portion of the socket base  41 . Referring to FIG. 4B, the through hole  42  is formed with a shape in accordance with the shape of a head section  32  so that the head section  32 , provided so as to protrude from the supporting unit  30 , is fitted through the through hole  42 . It is desirable that the through hole  42  be provided at a location where the top surface (heat transfer surface  31 ) of the head section  32 , fitted through the through hole  42 , contacts a high-heat-transfer-coefficient portion of the surface of the semiconductor module  10 . In addition, it is desirable for the area of the through hole  42  to be large from the viewpoint of making the top surface, that is, the heat transfer surface  31  of the head section  32  large. The formation of the through hole  42  is not limited to the case where it is completely formed in the inside portion of the socket base  41 , so that a portion thereof may appear at a side surface of the socket base  41 .  
         [0051]    Referring to FIGS. 2 and 3, the environmental temperature test is conducted with the semiconductor module  10 , mounted to the socket  40 , being sandwiched by supporting units  20  and  30  from above and below the semiconductor module  10 .  
         [0052]    Referring to FIGS. 2, 3, and  4 , in the lower supporting unit  30 , which forms the temperature controlling device, the head section  32 , formed of a material which conducts heat well (such as copper) and having a rectangular parallelepiped shape, is provided on the top surface of a unit support  35 , serving as a base of the supporting unit  30 , by interposing an heat insulating section  33  (which is a layer of heat insulating material) between the top surface of the unit support  35  and the head section  32 . The head section  32  is loosely fitted and passed through the through hole  42  of the socket  40 , so that the top surface of the head section  32  protrudes from the top surface of the socket base  41 . The top surface of the head section  32  is formed as a flat head transfer surface  31 , and is in close contact with the bottom surface of the heat-dissipating plate  12  of the semiconductor module  10  sandwiched by the supporting units  20  and  30 . A hollow  38  is formed in the head section  32  from the bottom surface thereof, with a platinum resistance temperature sensor  34  being attached to the inside portion of the head section  32 . The lower supporting unit  30  is installed on a device base  50  of the temperature test device serving as a heat sink.  
         [0053]    The upper supporting unit  20 , which forms the temperature controlling device, includes an temperature equalizing block  22  which is in close contact with the bottom surface of a temperature regulator  21 , comprising a Peltier element, and which is formed of a material which conducts heat well. The temperature regulator  21  varies the temperature of the temperature equalizing block  22  by discharging or absorbing heat being transferred towards the temperature equalizing block  22 . A heat exchanger  23  is provided on the top surface of the temperature regulator  21 , and processes waste heat and absorbed heat of the temperature regulator  21 . For the heat exchanger  23 , for example, an air cooling type or a liquid cooling type may be used. The bottom surface of the temperature equalizing block  22  is formed as a flat heat transfer surface  25 . Springs  24  are provided above the heat exchanger  23 , and push down the temperature equalizing block  22 , the temperature regulator  21 , and the heat exchanger  23 . By this, the heat transfer surface  25  pushes down on and is brought into close contact with the top surface of the package  13  of the semiconductor module  10 . From the view point of more closely contacting the heat transfer surface  25  and the package  13 , the larger the pushing forces of the springs  24 , the better. Therefore, the pushing forces of the springs  24  are made large within a range allowed by the strength of the package  13 . In this embodiment, the pushing force is set at a value that is automatically selected in accordance with the material of the package. The strength of the package  13  is ordinarily virtually determined based on the package material. Therefore, by setting the pushing force in accordance with the package material, a proper pushing force can be easily obtained.  
         [0054]    Next, a description of controlling the temperature of the semiconductor module in the environmental temperature test will be given. Referring to FIG. 2, the pins  15  of the semiconductor module  10  is inserted into the pin holes  45  of the socket  40  in order to mount the semiconductor module  10  onto the socket base  41 . Next, referring to FIG. 3, the head section  32  of the lower supporting unit  30  is passed through the through hole  42  of the socket base  41  in order to mount the socket  40  onto the supporting unit  30  so that the top surface, that is, the heat transfer surface  31  of the head section  32  is in close contact with the bottom surface of the heat-dissipating plate  12  of the semiconductor module  10 . Here, the semiconductor module  10  and the socket  40  are held so that the heat-dissipating plate  12  is placed and supported on the heat transfer surface  31 .  
         [0055]    Then, the upper supporting unit  20  moves down from above the semiconductor module  10 , so that the bottom surface, that is, the heat transfer surface  25  of the temperature equalizing block  22  comes into close contact with and pushes down on the top surface of the package  13  of the semiconductor module  10 . Therefore, the semiconductor module  10  is supported by being sandwiched between the heat transfer surfaces  25  and  31  of the corresponding supporting units  20  and  30  from above and below the semiconductor module  10 . Here, the plurality of springs  24  are used for pushing down on the package  13 . By this, even if the top surface of the package  13  is tilted from the horizontal direction, the heat transfer surface  25  tilts along and is in close contact with the top surface of the package  13 .  
         [0056]    Next, a probe (not shown), which is an electrically measuring instrument, is brought into contact with the pads  43  at the side surfaces of the socket base  41  in order to electrically connect it with the semiconductor module  10 . The optical fiber  14  is connected to an optical measuring device (not shown), such as a light intensity measuring device or a light wavelength measuring device.  
         [0057]    Next, the semiconductor module  10  is driven to start optical measurements. Thereafter, temperature control of the semiconductor module  10  is started in accordance with a temperature sequence set for test use. In this temperature control, control electrical power to the temperature regulator  21  of the upper supporting unit  20  is adjusted in order to control the temperature of the head section  32  of the lower supporting unit  30  measured by the temperature sensor  34  so as to be equal to a predetermined temperature determined by the specified temperature sequence. By this, the temperature of the semiconductor module  10  is precisely controlled at a predetermined temperature value.  
         [0058]    A temperature controlling device of the second embodiment of the present invention relates to a device including temperature regulators at the upper and lower supporting units. FIG. 5 is a sectional view of the assembly of the second embodiment, showing the structure of the temperature controlling device.  
         [0059]    Referring to FIG. 5, the socket and the semiconductor module used in the embodiment are similar to the above-described socket and semiconductor module used in the first embodiment.  
         [0060]    Referring to FIG. 5, a lower supporting unit  30  used in the embodiment differs from the lower supporting unit (the supporting unit  30  shown in FIGS. 2 and 3) used in the above-described first embodiment in the following ways. First, a heat insulating section  33  for shielding a head section  32  is not provided. Therefore, heat exchange between the head section  32  and the unit support  35  cannot be prevented. Rather, in this embodiment, it is preferable to make the difference between the temperatures of the head section  32  and the unit support  35  small by forming the unit support  35  using a material which conducts heat well. Second, a temperature regulator  36  that can change the temperature of a supporting unit  30  is provided. The temperature regulator  36  comprises, for example, a Peltier element, and is provided in close contact with the bottom surface of the unit support  35 . In addition, a heat exchanger  37  for processing waste heat of the temperature regulator  36  is provided below the temperature regulator  36 . The other structural features, including the structural features that a heat transfer surface  31  is formed as the top surface of the head section  32  fitted through a through hole  42  of a socket  40 , and that a temperature sensor  34  for measuring the temperature of the head section  32  is provided, are the same as those of the lower supporting unit  30  used in the first embodiment.  
         [0061]    The upper supporting unit  20  used in the embodiment is the same as the upper supporting unit  20  used in the first embodiment except that a temperature sensor  26  for measuring the temperature of an temperature equalizing block  22  is provided.  
         [0062]    The above-described temperature controlling device of the second embodiment of the present invention has two methods of use. Hereunder, referring to FIG. 5, the procedure for controlling the temperature of the semiconductor module  10  after the semiconductor module  10  has been interposed between the upper and the lower supporting units  20  and  30  will be described.  
         [0063]    In the first method of use, as in the first embodiment, the temperature regulator  21  of the upper supporting unit  20  is controlled so that the temperature of the head section  32  is maintained at a predetermined temperature. First, electrical power to the temperature regulator  36  of the lower supporting unit  31  is controlled in order to maintain the temperature of the head section  32  measured at the temperature sensor  34  at a temperature (for example, within a certain temperature range of from 24° C. to 26° C) close to the predetermined temperature (such as 25° C.). After the temperature of the head section  32  has become steady, the electrical power to the temperature regulator  36  is fixed at this value. Instead of fixing the electrical power, it is possible to measure the temperature of the top surface of the temperature regulator  36  or the temperature of the unit support  35  in order to control the electrical power so that the temperature is constant. By this, the effects of changes in the environmental temperature of the device, such as to room temperature, on the controlling of the temperature of the head section  32  can be reduced.  
         [0064]    Then, electrical power is supplied to the temperature regulator  21  of the upper supporting unit  20  in order to control the temperature of the temperature equalizing block  22  so that the temperature of the head section  32  is equal to the predetermined temperature. When the temperature of the head section  32  has reached the predetermined temperature, electrical and optical tests of the semiconductor module  10  are started.  
         [0065]    In this method of use, since the difference between the temperatures of the unit support  35  and the head section  32  is small, the amount of heat flowing into and out of the head section  32  is small. Therefore, the difference between the temperatures of the head section  32  and the semiconductor module  10  also becomes small, thereby making it possible to precisely control the semiconductor module  10  at its predetermined temperature value. In addition, it is possible to monitor the temperature of the temperature equalizing block  22  by the temperature sensor  26 . In this case, it is possible to confirm that the temperature of the semiconductor module is controlled within a temperature range measured by the two temperature sensors  26  and  34  provided at the upper and lower supporting units  20  and  30 , respectively.  
         [0066]    In the second method of use, the temperature of the semiconductor module  10  is controlled at the predetermined temperature by maintaining the temperatures of the upper and lower supporting units  20  and  30  at different temperature values. In this method, the temperature regulator  21  of the upper supporting unit  20  is controlled in order to cause the temperature of the temperature equalizing block  22  measured by the temperature sensor  26  to be equal to a previously determined temperature value. On the other hand, the temperature regulator  36  of the lower supporting unit  30  is controlled in order to cause the temperature of the head section  32  measured by the temperature sensor  34  to be equal to a previously determined temperature that differs from that of the temperature equalizing block  22 . For example, when the predetermined temperature of the semiconductor module  10  is 25° C., the temperature regulators  21  and  36  are controlled so that the temperature of the temperature equalizing block  22  is 26° C., and the temperature of the head section  32  is 24° C., respectively. At this time, when the difference between the temperatures of the temperature equalizing block  22  and the head section  32  is made large, the amount of heat flowing to the heat transfer surfaces  25  and  31  becomes large, so that the temperature controlling operation is more stably carried out. This temperature control is carried out separately for the upper and lower supporting units  20  and  30 . For example, the temperature of the temperature equalizing block  22  is controlled by controlling the temperature regulator  21  of the upper supporting unit  20  by using an output from the temperature sensor  26  provided inside the temperature equalizing block  22 . On the other hand, the temperature of the head section  32  is controlled by controlling the temperature regulator  36  of the lower supporting unit  30  by using an output from the temperature sensor  34  provided inside the head section  32 .  
         [0067]    In this second method of use, it is guaranteed that the temperature of the semiconductor module  10  is maintained within a temperature range intermediate between those of the temperature equalizing block  22  and the head section  32 . When the heat resistance between the semiconductor module  10  and the temperature equalizing block  22  and between the semiconductor module  10  and the head section  32  or the ratio of the heat resistances of the component parts can be known, it is possible to calculate the exact temperature of the semiconductor module from the temperatures of the temperature equalizing block  22  and the head section  32 . Therefore, it is possible to cause the temperature of the semiconductor module  10  to be exactly equal to the predetermined temperature, such as 25° C., specified in the test specification.  
         [0068]    The heat resistance ratio can be experimentally obtained. For example, while the temperature of the semiconductor module  10  is maintained at a constant value in a thermal equilibrium state, the temperature of either one of the supporting units  20  and  30  is raised, while the temperature of either one of the other supporting units  20  and  30  is lowered. The heat resistance ratio is the ratio between the amount of temperature rise and the amount of temperature fall. Whether or not the temperature of the semiconductor module  10  is maintained at a constant value can be confirmed by directly observing the temperature of the semiconductor module  10  with a radiation thermometer or by observing that the optical properties of the semiconductor module  10 , such as light intensity and wavelength, remain at constant values. When the temperature of the semiconductor module  10  is directly measured, the heat resistances are immediately obtained.  
         [0069]    A temperature controlling device of a third embodiment of the present invention will be described by referring to the above-described temperature controlling device of the first embodiment of the present invention. Referring to FIGS. 2, 3, and  4 , a first unit used in this embodiment is similar to the first supporting unit  20  used in the first embodiment, and includes an temperature equalizing block  22  at one surface of a temperature regulator  21  and a heat exchanger  23  at the other surface of the temperature regulator  21 . A heat transfer surface  25  is formed at the temperature equalizing block  22 , and comes into thermal contact with a semiconductor package  13  by being pushed by springs  24 . Here, the temperature of the first unit is controlled so that the temperature of a particular portion of a semiconductor module  10  is equal to a predetermined temperature. Here, ordinarily, a portion, such as a heat-dissipating plate  12 , suitable for temperature control of the semiconductor module  10  is selected as the particular portion. A second unit used in the embodiment may be any unit as long as the unit measures the surface temperature of a portion of the semiconductor module  10  other than the aforementioned particular portion, and is similar to the second supporting unit  30  used in the first embodiment. The second unit may be one not including the heat insulating section of the second supporting unit  30  used in the first embodiment. The second unit may be a unit for measuring the surface temperature of the aforementioned particular portion. In that case, the temperature of the first unit is controlled so that the temperature of the semiconductor module  10  measured by the second unit equals the predetermined temperature.  
         [0070]    According to one embodiment of the present invention, since the amount of heat flowing into or out of an area which is brought into contact with the semiconductor module is made small by shielding portions near this area from heat, the difference between the temperatures of the semiconductor module and the temperature sensor or the temperature sensors becomes small, so that the temperature of the semiconductor module can be precisely controlled at the predetermined temperature value.  
         [0071]    According to another embodiment of the invention, since the temperature of the semiconductor module is maintained at the predetermined temperature value by bringing the semiconductor module into contact with the heat transfer surfaces whose temperatures are controlled at different temperature values, it is possible to cause the temperature of the semiconductor module to be exactly equal to the predetermined temperature value.  
         [0072]    Accordingly, according to the present invention, since the temperature of the semiconductor module can be precisely controlled, a precise temperature test can be conducted, which contributes to increasing the reliability of a semiconductor device.