Abstract:
An exemplary embodiment of the present invention aims at providing a cooling structure for a test device which has sufficient cooling performance and can reduce the size of the heat sink. The cooling structure for a test device has first and second plates, a cover with a hole on the first plate, and a heat sink attached to the cover. When the vacuum suction is applied in a test space which is formed between the first and the second plates, air is drawn through the hole of the cover and applied onto the heat sink.

Description:
[0001]    This application is based upon and claims the benefit of priority from Japanese patent application No. 2009-245486, filed on Oct. 26, 2009, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    The present invention relates to a cooling structure for a test device and a method for testing a device. More particularly, it, relates to a cooling structure of an in-circuit test fixture that cools a device in an in-circuit tester which brings a probe into contact with a circuit substrate to be tested, which extracts a signal through the probe, and which tests a circuit. 
         [0003]    A known technique for using an in-circuit test fixture is described below. The technique is that a device to be tested is set up on a table, the same electric power and signal as those in a state where the device is mounted on real equipment are input to the device, and a test is conducted while a probe located on the table is brought into contact with a predetermined test point on a circuit substrate to be tested. 
         [0004]    JP-A-S59-6552 discloses a related “multi-pin prober”. In the multi-pin prober, after the circuit substrate to be tested on which the device is mounted has been set up on a test fixture main body, a vacuum suction is applied in a space surrounded between the circuit substrate to be tested and the prober. As a result, a probing pad contacts a contact pin on the prober and the device test is conducted. In this situation, a heater/cooler which is located below the prober is driven under control so as to prevent a positional displacement caused by a difference in thermal expansion between the circuit substrate to be tested and the prober due to heating of the device on the circuit substrate to be tested. On the other hand, JP-A-H11-145349 discloses a technique in which a heat sink is located on a heating member (a device in the case of JP-A-S59-6552), and a cooling air is fed to a fin disposed on the heat sink at a low level to generate a convection. 
         [0005]    In addition to the in-circuit test fixture disclosed in JP-A-S59-6552, a technique illustrated in  FIG. 3  is known. 
         [0006]    An in-circuit test fixture  50  illustrated in  FIG. 3  conducts the test in such a manner that a circuit substrate S having a device D is held in a test space  60  between a top probe plate  51  and a bottom probe plate  52 , and probes  53  and  54  are applied to the circuit substrate S to apply and observe an electric signal from a tester. 
         [0007]    The top probe plate  51  and the bottom probe plate  52  are so disposed as to come closer to or go away from the circuit substrate S which is disposed in an intermediate portion thereof as indicated by arrows A-B. When the test space  60  is sucked by vacuum as indicated by symbol C, the top probe plate  51  and the bottom probe plate  52  approach each other, and the probes  53  and  54  disposed on the plates  51  and  52  contact the circuit substrate S having the device D. 
         [0008]    On the other hand, a cover  55  is disposed on the top probe plate  51  at a side where the device D on the circuit substrate S is arranged so as to sandwich a notch  51 A. A heat sink  58  that is urged by springs  57  each inserted into a pin  56  in a direction indicated by an arrow A is disposed within the cover  55 . When vacuum suction within the test space  60  indicated by the symbol C allows the top probe plate  51  and the bottom probe plate  52  to approach each other, the heat sink  58  comes in close contact with the device D on the circuit substrate S. 
         [0009]    Since the above-mentioned test space  60  within the fixture including the cover  55  is of a sealed structure, in applying the probes  53  and  54  to the circuit substrate S, a vacuum system in which the circuit substrate  5  is held between the top probe plate  51  and the bottom probe plate  52  by the aid of the vacuum suction C to apply the probes  53  and  54  is most popularly employed. In such vacuum suction C, the probes  53  and  54  stop at the time of contacting the circuit substrate S. However, because the entire testing space is in a sealed structure, the test space  60  within the fixture comes to a state close to vacuum, and the probes  53  and  54  are kept in contact with the circuit substrate S. 
         [0010]    In the in-circuit thus configured, there is a structure in which the circuit structure S is cooled by natural cooling not using the above-mentioned heat sink  58 . However, there is a case in which a large amount of heat is generated from the device D by higher processing speed and higher integration of LSI, which cannot be dealt with by the natural cooling. 
         [0011]    As a countermeasure thereagainst, it is conceivable that, for example, a fan indicated by symbol  61  is fitted to the heat sink  58 . However, because the sealed space  60  of the in-circuit test fixture  50  is close to vacuum, a problem arises such that even if the fan  61  is fitted thereto, the convection of air is not generated, and sufficient cooling cannot be obtained. Further, when the size of the heat sink  58  is increased in order to obtain a sufficient cooling performance, a problem arises in that a sufficient space for location of the probes  53  and  54  cannot be ensured around the circuit substrate S having the device D. 
         [0012]    The present invention has been made in view of the above-mentioned circumstances, and aims at providing a cooling structure of an in-circuit test fixture which has sufficient cooling performance and can reduce the size of the heat sink. 
       SUMMARY OF THE INVENTION 
       [0013]    An exemplary object of the present invention is to provide a cooling structure for a test device, and a method for testing a device which has sufficient cooling performance and can reduce the size of the heat sink. 
         [0014]    According to a non-limiting illustrative embodiment, a cooling structure for a test device comprising: a first probe plate; a second probe plate; a cover on the first probe plate; a probe on at least one of the first and second probe plates; and a heat sink attached to the cover; wherein the cover has a hole, wherein a test space is formed between the first and second plates, wherein the probe is capable of connecting to a device to be tested when a vacuum suction is applied to the test space, and wherein when the vacuum suction is applied, air is drawn through the hole and applied onto the heat sink. 
         [0015]    According to another non-limiting illustrative embodiment, a method of cooling a device being tested comprising: placing the device in a test space formed between a first probe plate and a second probe plate, and applying a vacuum suction to the test space, wherein when the vacuum is applied, a probe on at least one of the first and second probe plates connects to the device, and wherein when the vacuum is applied, air is drawn through a hole in a cover on the first probe plate and the air is applied to a heat sink attached to the cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0016]    Other features and advantages of various embodiments of the present invention will become apparent by the following detailed description and the accompanying drawing, wherein: 
           [0017]      FIG. 1  is a front view including a partial cross section of the cooling structure for a test device in the first exemplary embodiment of the present invention. 
           [0018]      FIG. 2  is a plan view of a cover illustrated from the upper side of  FIG. 1 . 
           [0019]      FIG. 3  is a front view including a partial cross section of the cooling structure for a test device in the related art. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The present invention will now be described more fully with reference to the accompanying drawings, in which examples of embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth therein; rather, these examples of embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. 
         [0021]    A first exemplary embodiment of the present invention will be described in detail with reference to  FIGS. 1 and 2 . 
         [0022]    An in-circuit test fixture  10  shown in  FIG. 1  includes a top probe plate  11  and a bottom probe plate  12  which are so disposed as to come closer to or go away from each other as indicated by arrows A-B. In an in-circuit test, a circuit substrate S on which a device D is mounted is held in an intermediate portion between the top probe plate  11  and the bottom probe plate  12 . 
         [0023]    Also, the top probe plate  11  and the bottom probe plate  12  are equipped with probes  13  and  14 , respectively. When the circuit substrate S is held between the top probe plate  11  and the bottom probe plate  12 , the respective probes  13  and  14  are brought into contact with test points on the circuit substrate S, to thereby apply and observe an electric signal from a tester through the probes  13  and  14  to implement the test of the circuit substrate S. 
         [0024]    Also, the test space  20  between the top probe plate  11  and the bottom probe plate  12  is connected to a vacuum source (not shown). When the test space  20  is sucked by vacuum as indicated by symbol C 1 , the top probe plate  11  and the bottom probe plate  12  come closer to each other, and the probes  13  and  14  which are disposed on the plates  11  and  12 , respectively, contact the test points of the circuit substrate S. 
         [0025]    A cover  15  is disposed on the top probe plate  11  at a side where the device D on the circuit substrate S is arranged so as to sandwich a notch  11 A. A heat sink  18  that is urged by springs  17  each inserted into a pin  16  in a direction indicated by an arrow A is disposed within the cover  15 . 
         [0026]    The pins  16  are arranged along the directions indicated by the arrows A-B which are orthogonal to the plates  11  and  12 , and the heat sink  18  is so disposed as to be movable along the pins  16  in the directions indicated by the arrows A-B. Also, the springs  17  are compression springs each formed in a coil shape, and are arranged between the cover  15  and the heat sink  18  to urge the heat sink  18  in the direction indicated by the arrow A. 
         [0027]    Then, when the vacuum suction indicated by the symbol C 1  allows the top probe plate  11  and the bottom probe plate  12  to approach each other, the urging of the spring  17  brings the heat sink  18  into close contact with the device D on the circuit substrate S. 
         [0028]    The cover  15  is provided with a suction hole  19  for taking in external air. 
         [0029]    As shown in  FIG. 2 , the suction hole  19  is circular. The suction hole  19  is arranged at an upper side of the cover  15  so as to face an upper surface of the heat sink  18 . Then, air taken in from outside the test fixture as indicated by symbol C 2  through the suction hole  19  when the test space  20  is subjected to vacuum suction C 1  is introduced into the cover  15 , and blown to the heat sink  18  located in the cover  15 . As a result, the heat sink  18  is cooled. The size of the suction hole  19  is determined on the basis of the vacuum suction, and the number and position of the probes  13  and  14  so that no problem arise with the contact of the probes  13 ,  14  and the circuit substrate S. 
         [0030]    The action of the in-circuit test fixture configured as described above will now be described. 
         [0031]    First, when vacuum suction is conducted as indicated by the symbol C 1 , the top probe plate  11  and the bottom probe plate  12  approach each other, and the probes  13  and  14  disposed on the plates  11  and  12 , respectively, contact the test points of the circuit substrate S. In this state, the device D and the circuit substrate S are tested and observed. In this situation, the suction of the external air from the suction hole  19  as indicated by the symbol C 2  allows air to be applied onto the upper surface of the heat sink  18 , thereby preventing the overheat of the heat sink  18 . 
         [0032]    Also, the vacuum suction C 1  is continued even after the probes  13  and  14  contact the circuit substrate S, to thereby continue the suction of the external air from the suction hole  19  as indicated by the symbol C 2 . As a result, because air is constantly applied to the upper surface of the heat sink  18 , overheating of the heat sink  18  is prevented, and the cooling performance of the heat sink  18  does not deteriorate. Thereafter, upon completion of the device test, the vacuum suction C 1  stops, and the circuit substrate S is released. 
         [0033]    As has been described above, according to the in-circuit test fixture described in this embodiment, the cover  15  having the heat sink  18  for cooling the device D therein is disposed on the probe plate  11  at the side where the device D on the circuit substrate S is arranged. Also, the cover  15  is provided with the suction hole  19  for taking in the external air. Therefore, when the test space  20  is subjected to the vacuum suction C 1 , the external air taken in through the suction hole  19  is introduced into the heat sink  18  (symbol C 2 ) within the cover  15 , to thereby cool the heat sink  18 . As a result, as compared with the conventional in-circuit test fixture that fans air by the fan under vacuum, the heat sink  18  can be efficiently cooled, and the heat sink  18  can be reduced in size. In the above embodiment, the suction hole  19  is circular. However, the shape is not limited to a circle, but may be shaped, for example, as a rectangle or a triangle. Also, the number of suction holes  19  is not limited to one, but a plurality of suction holes  19  may be formed. Also, the suction hole  19  is not limited to being placed on the upper portion of the cover  15 , but may be disposed at a side of the cover  15  as long as air sucked from outside the test fixture is applied to the heat sink  18 . 
         [0034]    Also, the number and size of the suction holes  19  are determined on the basis of the vacuum suction and the number and position of the probes  13  and  14  so that no problems arise with the contact of the probes  13  and  14  with the circuit substrate S. 
         [0035]    The embodiment of the present invention has been described above in detail with reference to the drawings. However, specific configurations are not limited to this embodiment, and the design can be modified without departing from the subject matter of the present invention.