Abstract:
It is an object to use an additional circuit to increase speed and functioning of an existing test apparatus at a low cost. Provided is a test apparatus that is connected to a socket board corresponding to a type of device under test and tests the device under test. The test apparatus comprises a test head including therein a test module that tests the device under test; a function board that is connected to the test module in the test head via a cable and also connected to the socket board; and an additional circuit that is loaded on the function board and connected to the test module and the device under test.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a test apparatus and a connection apparatus. 
         [0003]    2. Related Art 
         [0004]    A test apparatus is known that tests a semiconductor device, as in Patent Document 1, for example. A manufacturer of semiconductor devices must continue developing new test apparatuses to keep up with the higher speeds and functioning of the devices. Implementing a new test apparatus, however, increases the cost of the devices and decreases the operating efficiency of test apparatuses already in use.
   Patent Document 1: Japanese Patent Application Publication No. 2008-292488   
 
         [0006]    There are cases where the board of an existing test apparatus on which devices under test are loaded is provided with an additional circuit, thereby enabling the test apparatus to test devices with higher speeds and functioning. As a result, there is less need to implement new test apparatuses and the operating efficiency of existing test apparatuses can be improved. 
         [0007]    This technique increases manufacturing cost since the additional circuit is a circuit for testing devices with higher speeds and functioning. Furthermore, the boards on which the devices under test are placed differ depending on the type of device under test. Accordingly, a different additional circuit must be created for each board on which a device under test is provided, thereby increasing the cost. 
         [0008]    In addition, when an additional circuit is disposed on a board, the area in which devices under test can be provided is decreased. Accordingly, when an additional circuit is disposed on a board on which devices under test are placed, the number of devices under test that can be tested in parallel is decreased. 
         [0009]    Furthermore, a board on which devices under test are placed experiences a force when a handler attaches or detaches the devices under test. When performing a quick reliability test or the like, a board on which devices under test are placed is sealed in a chamber and heated along with the devices under test. Accordingly, an additional circuit disposed on a board on which devices under test are placed is prone to mechanical stress and thermal stress during testing. 
       SUMMARY 
       [0010]    Therefore, it is an object of an aspect of the innovations herein to provide a test apparatus and a connection apparatus, which are capable of overcoming the above drawbacks accompanying the related art. The above and other objects can be achieved by combinations described in the independent claims. According to a first aspect related to the innovations herein, provided is a test apparatus that is connected to a socket board corresponding to a type of device under test and tests the device under test. The test apparatus comprises a test head including therein a test module that tests the device under test; a function board that is connected to the test module in the test head via a cable and also connected to the socket board; and an additional circuit that is loaded on the function board and connected to the test module and the device under test. Also provided is a connection apparatus used by the test apparatus. 
         [0011]    The summary clause does not necessarily describe all necessary features of the embodiments of the present invention. The present invention may also be a sub-combination of the features described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a configuration of a test apparatus  10  according to an embodiment of the present invention, along with devices under test  200 . 
           [0013]      FIG. 2  shows a configuration of the connection apparatus  14  according to the present embodiment, along with a device under test  200  and the test head  12 . 
           [0014]      FIG. 3  shows an exemplary mechanical configuration of the connection apparatus  14  according to the present embodiment, along with devices under test  200 . 
           [0015]      FIG. 4  shows an exemplary mechanical structure of the connection apparatus  14  according to the present embodiment, along with a line indicating a portion that is exchanged together with replaceable parts of the device under test  200 . 
           [0016]      FIG. 5  shows a partial structure of the connection apparatus  14  according to the present embodiment. 
           [0017]      FIG. 6  shows an exemplary component for injecting or expelling cooling gas according to the present embodiment. 
           [0018]      FIG. 7  shows an exemplary connection of a component for injecting or expelling cooling gas according to the present embodiment. 
           [0019]      FIG. 8  shows an exemplary bottom surface of the function board  50 , i.e. the surface facing the test head  12 , according to the present embodiment. 
           [0020]      FIG. 9  shows an exemplary arrangement of connection units  28  and devices under test  200  connected to the socket board  34 , according to the present embodiment. 
           [0021]      FIG. 10  shows an exemplary connection unit  28  and connection unit frame  40  according to the present embodiment. 
           [0022]      FIG. 11  shows an exemplary internal configuration of a connection unit  28  according to the present embodiment. 
           [0023]      FIG. 12  shows an exemplary connection of the function board  50 , the connection unit  28 , and the connection unit frame  40  in the function board frame  60  according to the present embodiment. 
           [0024]      FIG. 13  shows an exemplary connection of the function board  50 , the connection unit frame  40 , the side wall  42 , the socket board  34 , and the socket frame  38  in the function board frame  60  according to the present embodiment. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0025]    Hereinafter, some embodiments of the present invention will be described. The embodiments do not limit the invention according to the claims, and all the combinations of the features described in the embodiments are not necessarily essential to means provided by aspects of the invention. 
         [0026]      FIG. 1  shows a configuration of a test apparatus  10  according to an embodiment of the present invention, along with devices under test  200 . The test apparatus  10  of the present embodiment tests at least one device under test  200 . 
         [0027]    The test apparatus  10  includes a test head  12 , a connection apparatus  14 , and a control apparatus  16 . The test head  12  includes at least one test module  18  therein for testing the device under test  200 . Each test module  18  exchanges signals with the corresponding device under test  200  to test this device under test  200 . 
         [0028]    The connection apparatus  14  is disposed on the test head  12 . The devices under test  200  are disposed on the top surface of the connection apparatus  14 , i.e. the surface that is opposite the surface connected to the test head  12 . The devices under test  200  can be attached to or detached from the connection apparatus  14  by a handler. The connection apparatus  14  provides an electrical connection between a terminal of each test module  18  and a terminal of the corresponding device under test  200 . 
         [0029]    The control apparatus  16  may be a computer executing a program, for example, for controlling the overall test apparatus  10 . The control apparatus  16  controls each test module  18  by communicating with the test module  18  in the test head  12  according to the program. 
         [0030]      FIG. 2  shows a configuration of the connection apparatus  14  according to the present embodiment, along with a device under test  200  and the test head  12 . The connection apparatus  14  includes a motherboard  22 , a function expanding section  24 , and a device connecting section  26 . 
         [0031]    The motherboard  22  is disposed on the test head  12 . The motherboard  22  houses a signal cable, which provides a connection between the function expanding section  24  and the test module  18  in the test head  12 , and a power supply cable, which provides a connection between the function expanding section  24  and a power supply apparatus, for example. 
         [0032]    The function expanding section  24  is disposed on top of the motherboard  22 . In other words, the function expanding section  24  is connected to the surface of the motherboard  22  that is opposite the surface connected to the test head  12 . The function expanding section  24  includes a connector on the motherboard  22  side surface thereof, i.e. the surface facing the test head  12 . The connector is connected to the power supply cable, which is connected to the power supply apparatus, and the signal cable, which is connected to the test module  18 , housed in the motherboard  22 . 
         [0033]    The device connecting section  26  is disposed on top of the function expanding section  24 . In other words, the device connecting section  26  is connected to a surface of the function expanding section  24  that is opposite the surface connected to the motherboard  22 , i.e. opposite the surface of the function expanding section  24  facing the test head  12 . The device under test  200  is loaded on the top surface of the device connecting section  26 , i.e. the surface facing away from the test head  12 . The device connecting section  26  provides an electrical connection between the function expanding section  24  and the device under test  200  loaded thereon. 
         [0034]    The function expanding section  24  includes a plurality of connection units  28  and an additional circuit  30 . The additional circuit  30  is disposed on the motherboard  22  side surface of the function expanding section  24 , i.e. the surface facing the test head  12 . 
         [0035]    The additional circuit  30  is electrically connected to the device under test  200  and the test module  18  in the test head  12 . The additional circuit  30  is an integrated circuit device that is controlled by the test module  18  in the test head  12  to test the device under test  200 . The additional circuit  30  may be an FPGA (Field Programmable Gate Array). The additional circuit  30  may be a plurality of integrated circuit devices. 
         [0036]    The additional circuit  30  may exchange signals in parallel with a plurality of devices under test  200 , according to a signal from one test module  18 . As a result, the additional circuit  30  can increase the number of devices under test  200  that a single test module  18  can test at the same time. 
         [0037]    The additional circuit  30  may convert a signal received from the test module  18  into a signal with a higher clock than the received signal, for example, and supply this signal to the device under test  200 . As another example, the additional circuit  30  may convert a signal received from the test module  18  into a signal with a lower clock than the received signal, and supply this signal to the device under test  200 . As a result, the additional circuit  30  can test a device under test  200  that operates with a higher clock than a device that the test module  18  is capable of testing. 
         [0038]    Each connection unit  28  is disposed on the surface of the function expanding section  24  that is not on the motherboard  22  side, i.e. the surface facing away from the test head  12 . The device connecting section  26  is electrically connected to the function expanding section  24  via the connection units  28 . The connection units  28  are not mechanically fixed by the connectors or the like to the device connecting section  26 , and provide an electrical connection between the device connecting section  26  and the function expanding section  24 . For example, the connection units  28  may include a plurality of pogo pins. In the present embodiment, the connection units  28  are fixed to the upper portion of the function expanding section  24 , but may instead be fixed to the device connecting section  26 , or may be fixed to neither the function expanding section  24  nor the device connecting section  26 . 
         [0039]    Since the connection units  28  are not mechanically fixed between the device connecting section  26  and the function expanding section  24 , the connection apparatus  14  described above enables the device connecting section  26  to be easily exchanged. As a result, the function expanding section  24  including the additional circuit  30  can be used to test a plurality of devices under test  200 , regardless of the type of the devices under test  200 . 
         [0040]    Furthermore, since the function expanding section  24  is disposed below the device connecting section  26 , the connection apparatus  14  enables the additional circuit  30  to be placed relatively far from the device under test  200 . As a result, the connection apparatus  14  enables the device under test  200  and the additional circuit  30  to be mechanically and thermally isolated from each other. Accordingly, with the connection apparatus  14 , transmission of heat or force applied to the device under test  200  to the additional circuit  30  can be restricted. Furthermore, with the connection apparatus  14 , heat generated by the additional circuit  30  and cooling for cooling the additional circuit  30  can be restricted from being transmitted to the device under test  200 . 
         [0041]    In the connection apparatus  14 , the additional circuit  30  is not disposed on the top surface of the device connecting section  26 . Accordingly, with the connection apparatus  14 , a large number of devices under test  200  can be loaded on the top surface of the device connecting section  26 , thereby enabling a large number of devices under test  200  to be tested in parallel. 
         [0042]      FIG. 3  shows an exemplary mechanical configuration of the connection apparatus  14  according to the present embodiment, along with devices under test  200 . 
         [0043]    The device connecting section  26  includes a socket board  34 , a socket frame  38 , and a side wall  42 . The function expanding section  24  includes a function board  50 , a connection unit  28 , a connection unit frame  40 , an additional circuit  30 , a heat sink  54 , and a function board frame  60 . 
         [0044]    The socket board  34  is a board-shaped substrate that includes a socket  36  on the top surface thereof, i.e. the surface facing away from the test head  12 . The socket  36  holds the device under test  200  in a manner enabling attachment and detachment by the handler. The bottom surface of the socket board  34 , i.e. the surface opposite the surface on which the socket  36  is disposed, is connected to the function board  50  via the connection units  28 . The socket board  34  holds the device under test  200  and also provides an electrical connection between the function board  50  on the bottom surface thereof and the device under test  200  held by the socket  36 . 
         [0045]    The socket frame  38  surrounds a region other than the portion of the top surface of the socket board  34  where the socket  36  is disposed. The socket frame  38  may be formed by SUS, for example. 
         [0046]    The side wall  42  surrounds the function board  50  from the sides when the socket board  34  and the function board  50  are connected. The side wall  42  may be formed of a material with low thermal conductivity, such as PEEK (polyethyl ethyl ketone) resin. The side wall  42  can prevent thermal transmission between the inside and the outside of the side wall  42 . 
         [0047]    The connection units  28  are disposed on the top surface of the function board  50 , i.e. the surface facing away from the test head  12 . The top surface of the function board  50  is electrically connected to the socket board  34  via the connection units  28 . 
         [0048]    The connection unit frame  40  is disposed on the top surface of the function board  50 , which is the surface facing away from the test head  12 . The connection unit frame  40  is shaped as a board with a thickness approximately equal to the thickness of the connection unit  28 , and includes a plurality of apertures. The apertures are positioned to correspond respectively to positions where the connection units  28  are to be arranged, and each aperture is approximately the same size as the corresponding connection unit  28 . The connection unit frame  40  can accurately connect terminals on the bottom surface of the socket board  34  and the terminals on the top surface of the function board  50  at corresponding positions to each other, using the connection units  28 . 
         [0049]    The connection unit frame  40  may be formed of a material with low thermal conductivity, such as a PEEK resin. The connection unit frame  40  can decrease thermal transmission between the region above the connection unit frame  40  and the region below the connection unit frame  40 . The connection unit frame  40  may include, in the surface thereof contacting the function board  50 , a space through which air passes. As a result, the connection unit frame  40  can further reduce the thermal transmission between the region thereabove and the region therebelow. The connection unit frame  40  can also absorb force applied to the device under test  200  by the handler or the like, thereby decreasing the force applied to the components below the connection unit frame  40 . 
         [0050]    The function board  50  includes a connector  58  on the bottom surface thereof, i.e. on the surface facing the test head  12 . The connector  58  is connected to the signal cable  80 , which is connected to the test module  18  in the test head  12 , and to the power supply cable  82 , which is connected to the power supply apparatus. 
         [0051]    The additional circuit  30  is an integrated circuit device, and is loaded on the bottom surface of the function board  50 , i.e. the surface facing the test head  12 . The additional circuit  30  is connected to the test module  18  in the test head  12  via the function board  50  and the signal cable  80 . The additional circuit  30  is connected to the device under test  200  via the function board  50  and the socket board  34 . 
         [0052]    The heat sink  54  is disposed on the surface of the additional circuit  30  that the function board  50  is not attached to. For example, the heat sink  54  may be a metal cylinder with one closed end, and the outer surface of the closed end may be attached to the additional circuit  30 . This heat sink  54  can dissipate heat generated by the additional circuit  30 , and can form a cooling chamber  70  having a substantially sealed space within the cylinder. 
         [0053]    The function board frame  60  is disposed on the bottom surface of the function board  50 , i.e. the surface facing the test head  12 . The function board frame  60  is shaped as a board with apertures formed at the positions corresponding to the additional circuit  30  and the connector  58 . The function board frame  60  holds the function board  50  and mechanically connects the function board  50  to the motherboard  22 . 
         [0054]    The motherboard  22  includes a motherboard frame  62 , a support section  64 , and a connector guiding section  66 . The motherboard frame  62  is loaded on the test head  12  and holds components that are disposed within the motherboard  22 . The support section  64  is disposed on the motherboard frame  62  and supports the function expanding section  24 . For example, the support section  64  fixes and supports the function board frame  60  of the function expanding section  24  from below. 
         [0055]    The motherboard  22  includes an injecting section  72 , an exhaust section  74 , an injection path  76 , and an exhaust path  78 . The injecting section  72  emits gas toward the function board  50  from the test head  12  side to cool the additional circuit  30 . In the present embodiment, the injecting section  72  emits gas into the space within the cooling chamber  70  formed by the heat sink  54 . The exhaust section  74  expels the gas from the space in the cooling chamber  70  formed by the heat sink  54 . 
         [0056]    The injection path  76  is a path for sending gas output from an external heat exchanger to the injecting section  72 . The exhaust path  78  is a path for returning the gas expelled from the exhaust section  74  to the external heat exchanger. 
         [0057]    The injecting section  72  and the exhaust section  74  can cool the additional circuit  30  via the heat sink  54 . The heat sink  54  forms the cooling chamber  70  having the sealed space therein, and therefore the additional circuit  30  can be efficiently cooled without cooling gas leaking to the outside. The gas circulated within the space in the cooling chamber  70  is preferably compressed dry air. In this way, condensation is prevented in the cooling chamber  70  when the temperature is low. 
         [0058]    The motherboard  22  includes the signal cable  80 , the power supply cable  82 , and a sub-board  84 . The signal cable  80  provides a connection between the test module  18  in the test head  12  and the function board  50 . The signal cable  80  may be a coaxial cable, for example. The power cable  82  may provide a connection between an external power supply apparatus and the function board  50 . The sub-board  84  is disposed within the motherboard  22 , between the function board  50  and the test module  18  of the test head  12 . 
         [0059]    The connection apparatus  14  may have a chamber  32  mounted thereon by the handler or the like when testing a device. The chamber  32  encloses the devices under test  200  so that the atmosphere around the devices under test  200  can be controlled to have a predetermined temperature and humidity. As a result, the test apparatus  10  can perform quick and reliable testing of devices under test  200 . 
         [0060]    The connection apparatus  14  of the present embodiment has the function board  50  disposed on the bottom surface of the socket board  34  and has the additional circuit  30  disposed on the surface of the function board  50  facing the test head  12 . Therefore, the connection apparatus  14  can prevent heat added to the device under test  200  from affecting the additional circuit  30 , and can prevent the device under test  200  from being affected by heating or cooling of the additional circuit  30 . Furthermore, the connection apparatus  14  can decrease the mechanical stress placed on the additional circuit  30  when the devices under test  200  are attached, for example. 
         [0061]    The connection apparatus  14  includes the socket frame  38 , the connection unit frame  40 , and the side wall  42 . Accordingly, the connection apparatus  14  can thermally isolate the space within the chamber  32  and the additional circuit  30  from each other. 
         [0062]    In the connection apparatus  14 , the additional circuit  30  is not disposed on the top surface of the socket board  34 . Accordingly, with the connection apparatus  14 , a large number of devices under test  200  can be attached to the top surface of the socket board  34 , thereby enabling a large number of devices under test  200  to be tested in parallel. 
         [0063]      FIG. 4  shows an exemplary mechanical structure of the connection apparatus  14  according to the present embodiment, along with a line indicating a portion that is exchanged together with replaceable parts of the device under test  200 . 
         [0064]    The connection apparatus  14  electrically connects the socket board  34  to the function board  50 , but the socket board  34  and the function board  50  are not mechanically fixed by connectors or the like. Accordingly, during maintenance or the like, the connection apparatus  14  enables the socket board  34  to be easily detached from the function board  50 . The portion of the connection apparatus  14  above the dotted line A 1 -A 2  in  FIG. 4  may be removed, for example. 
         [0065]    Accordingly, the connection apparatus  14  enables the function board  50  and the additional circuit  30  to be shared regardless of the type of the device under test  200 . As a result, the connection apparatus  14  can decrease the cost of testing. 
         [0066]      FIG. 5  shows a partial structure of the connection apparatus  14  according to the present embodiment. The socket board  34  may be a thin board with a substantially square planar shape, for example. The socket  36  and the socket frame  38 , which are not shown in  FIG. 5 , are disposed on the socket board  34 . 
         [0067]    The function board  50  is a thin board that is slightly smaller than the socket board  34 , and has a planar shape resembling that of the socket board  34 . The additional circuit  30  with the heat sink  54  attached thereto is disposed on the surface of the function board  50  that the socket board  34  is not connected to. 
         [0068]    The connection unit frame  40  is sandwiched between the function board  50  and the socket board  34 . The connection unit frame  40  is a board whose planar shape substantially matches that of the function board  50 . The connection unit frame  40  may be thicker than the function board  50  and the socket board  34 , and may have an aperture through which the connection unit  28  is inserted formed at a predetermined position in the planar surface thereof. The connection unit frame  40  has a groove formed in the surface thereof that contacts the function board  50 , enabling air to pass therethrough. The connection unit frame  40  prevents thermal transmission between the socket board  34  and the function board  50 . 
         [0069]    The side wall  42  is a cylinder with an inner circumference whose planar shape matches that of the function board  50  and the connection unit frame  40  and with an output circumference whose planar shape substantially matches that of the socket board  34 . The side wall  42  prevents thermal transmission between (i) the function board  50  and the additional circuit  30  and (ii) the atmosphere around the device under test  200 . 
         [0070]    The function board frame  60  supports the pair of the function board  50  and the socket board  34  from below. In the example of  FIG. 5 , the function board frame  60  supports eight pairs of a function board  50  and a socket board  34 . 
         [0071]    The support section  64  is a square frame having apertures formed therein, and is provided in the upper portion of the motherboard  22 . The support section  64  supports one or more function board frames  60 . In the example of  FIG. 5 , the support section  64  supports two function board frames  60 . 
         [0072]    The support section  64  includes a connector guiding section  66  therein. The connector guiding section  66  holds the power supply cable  82  and the signal cable  80  connected to the function board  50 . The support section  64  includes holes  85  in which components are arranged for the injection or expelling of cooling gas, and these holes  85  are arranged at positions corresponding respectively to additional circuits  30  disposed on respective function boards  50 . 
         [0073]      FIG. 6  shows an exemplary component for injecting and expelling cooling gas according to the present embodiment. As shown in  FIG. 6 , the component for injecting and expelling cooling gas to and from the additional circuit  30  may be a nozzle  86 . The nozzle  86  includes a base  87 , an injecting section  72 , and an exhaust section  74 . The nozzle  86  includes an annular packing  88  attached to the sides of the base  87 . A nozzle  86  such as this is attached in each of the holes  85  shown in  FIG. 5 . 
         [0074]      FIG. 7  shows an exemplary connection of a component for injecting and expelling cooling gas according to the present embodiment. The outer circumference of the base  87  of the nozzle  86  has a shape that is substantially the same as that of the open portion of the heat sink  54  formed as a cylinder. 
         [0075]    When the function board frame  60  on which the function board  50  is disposed is loaded in the connector guiding section  66 , the end of the open portion of the heat sink  54  contacts the annular packing  88 . As a result, the heat sink  54  and the nozzle  86  can form the cooling chamber  70  containing a sealed space. 
         [0076]    The injecting section  72  formed in the nozzle  86  can inject cooling gas into the space within the cooling chamber  70 . The exhaust section  74  formed in the nozzle  86  can expel gas from the space within the cooling chamber  70 . For example, the injecting section  72  may inject the gas from a position closer to the additional circuit  30  than the exhaust section  74 . As a result, the injecting section  72  and the exhaust section  74  can efficiently circulate the gas heated by the additional circuit  30 . 
         [0077]      FIG. 8  shows an exemplary bottom surface of the function board  50 , i.e. the surface facing the test head  12 , according to the present embodiment.  FIG. 9  shows an exemplary arrangement of connection units  28  and devices under test  200  connected to the socket board  34 , according to the present embodiment. 
         [0078]    As shown in  FIG. 8 , connectors  58 , one additional circuit  30 , and DC-DC conversion circuits  89  are disposed on the bottom surface of the function board  50  of the present embodiment. The connectors  58  may be LIF (Low Insertion Force) connectors that connect a plurality of coaxial signal lines. The DC-DC conversion circuits  89  increase or decrease the DC voltage supplied from the power supply apparatus to convert this DC voltage to a power supply voltage for the devices under test  200 . 
         [0079]    As shown in  FIG. 9 , a plurality of devices under test  200  may be disposed on the socket board  34 . In the present embodiment, eight devices under test  200  are disposed on the socket board  34 . A plurality of connection units  28  are connected to the socket board  34 . Each connection unit  28  has the same configuration. In the present embodiment, eight connection units  28  are respectively connected to the eight devices under test  200 . 
         [0080]    By using the socket board  34  and the function board  50  shown in  FIGS. 8 and 9 , the connection apparatus  14  enables a plurality of devices under test  200  to be equipped in correspondence with a single additional circuit  30 . As a result, the test apparatus  10  according to the present embodiment can test a plurality of devices under test  200  in parallel using a single additional circuit  30 . 
         [0081]      FIG. 10  shows an exemplary connection unit  28  and connection unit frame  40  according to the present embodiment. The connection unit  28  may be a component obtained by forming a plurality of pins integrally using a resin or the like. In the connection unit  28 , the tips of each pin are exposed on both the surface facing the socket board  34  and the surface facing the function board  50 . 
         [0082]    The connection unit frame  40  includes a plurality of apertures  120  that each have substantially the same shape as a corresponding connection unit  28  and that are arranged at positions corresponding to the connection units  28 . When inserted in the corresponding aperture  120 , each connection unit  28  is fixed by being sandwiched between the socket board  34  and the function board  50 . As a result, each connection unit  28  can provide an electrical connection between a terminal provided at a predetermined position on the socket board  34  and a terminal provided at a predetermined position on the function board  50 . 
         [0083]    The connection units  28  may be inserted to the connection unit frame  40  from the function board  50  side, for example. Each connection unit  28  has an engaging member  122  that protrudes to contact a portion of the connection unit frame  40  when the connection unit  28  is inserted to the connection unit frame  40 . With the connection unit frame  40  and connection units  28  described above, the connection units  28  are prevented from passing through the connection unit frame  40  during insertion. 
         [0084]      FIG. 11  shows an exemplary internal configuration of a connection unit  28  according to the present embodiment. The connection unit  28  may have a plurality of pins including a power supply pin  90 , a signal pin  92 , and a ground pin  94 . The power supply pin  90 , the signal pin  92 , and the ground pin  94  each include a function-board-side probe  102 , a socket-board-side probe  104 , and a probe connecting section  106 . 
         [0085]    Each function-board-side probe  102  is a metal probe exposed to the outside from the surface of the connection unit  28  facing the function board  50 . Each function-board-side probe  102  contacts a terminal pad  98  of the function board  50  when the socket board  34  is connected to the function board  50 . 
         [0086]    Each socket-board-side probe  104  is a metal probe exposed to the outside from the surface of the connection unit  28  facing the socket board  34 . Each socket-board-side probe  104  contacts a terminal pad  100  of the socket board  34  when the socket board  34  is connected to the function board  50 . 
         [0087]    Each probe connecting section  106  holds the corresponding function-board-side probe  102  in a manner to allow movement in the axial direction, and achieves this holding by applying an outward force using a spring or the like. Furthermore, each probe connecting section  106  holds the corresponding socket-board-side probe  104  in a manner to allow movement in the axial direction, and achieves this holding by applying an outward force using a spring or the like. Each probe connecting section  106  provides an electrical connection between the corresponding function-board-side probe  102  and socket-board-side probe  104 . 
         [0088]    The connection unit  28  includes fixing portions  108  that fixes the integrated power supply pin  90 , signal pin  92 , and ground pin  94  at predetermined locations. The fixing portions  108  hold each of the power supply pin  90 , the signal pin  92 , and the ground pin  94  via the ends of the probe connecting section  106  on the function board  50  side and the socket board  34  side. The fixing portions  108  may be a resin, for example. 
         [0089]    The power supply pin  90  connects to a power supply line. Accordingly, the power supply pin  90  preferably has a thicker transmission line than the signal pin  92 . The probe connecting section  106  of the power supply pin  90  is preferably covered by an insulating material or the like. The ground pin  94  connects to a ground line. Accordingly, the ground pin  94  preferably has a thicker transmission line than the signal pin  92 . 
         [0090]    In the connection unit  28  having the above configuration, the device connecting section  26  and the function expanding section  24  are electrically connected to each other without being mechanically fixed by connectors or the like. 
         [0091]      FIG. 12  shows an exemplary connection of the function board  50 , the connection unit  28 , and the connection unit frame  40  in the function board frame  60  according to the present embodiment.  FIG. 13  shows an exemplary connection of the function board  50 , the connection unit frame  40 , the side wall  42 , the socket board  34 , and the socket frame  38  in the function board frame  60  according to the present embodiment. 
         [0092]    As shown in  FIG. 12 , the connection unit  28  may be inserted in the connection unit frame  40  and attached to the function board  50 . The function board  50  with the connection unit frame  40  and the connection unit  28  attached thereto is disposed at a corresponding position on the function board frame  60 . 
         [0093]    As shown in  FIG. 13 , a unit obtained by integrally forming the side wall  42 , the socket board  34 , and the socket frame  38  is attached to the function board frame  60  on which the connection unit frame  40  and the function board  50  are disposed. Since each unit is integrally formed, the connection apparatus  14  described above enables easy manufacturing and maintenance. 
         [0094]    While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above described embodiments. It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiments. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the invention. 
         [0095]    The operations, procedures, steps, and stages of each process performed by an apparatus, system, program, and method shown in the claims, embodiments, or diagrams can be performed in any order as long as the order is not indicated by “prior to,” “before,” or the like and as long as the output from a previous process is not used in a later process. Even if the process flow is described using phrases such as “first” or “next” in the claims, embodiments, or diagrams, it does not necessarily mean that the process must be performed in this order.