Patent Publication Number: US-2011063812-A1

Title: Electronic device, method of manufacturing electronic device, and electronic equipment

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Applications No. 2009-210022 filed on Sep. 11, 2009, and No. 2010-061787 filed on Mar. 18, 2010, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to an electronic device including a semiconductor device and a circuit board, a method of manufacturing the electronic device, and electronic equipment including the electronic device. 
     BACKGROUND 
     One possible form of connection between a semiconductor device and a circuit board is flip-chip connection. Conventionally, solder bumps have been widely used for the flip-chip connection. In this case, the solder bumps are melted in a state arranged between electrodes of a semiconductor device and those of a circuit board, and then are solidified, for electrically connecting the semiconductor device and the circuit board by soldering. Further, there has been proposed a method of evaluating the connection reliability of such solder connection portions by a heat cycle test and a bending test. 
     As a method of connecting the semiconductor device and the circuit board, there have been known a method for connecting them using gold (Au) bumps and solder, a method for extending solder joints in a direction separating the semiconductor device and the circuit board from each other, etc. 
     Further, there have also conventionally been known a technique for connecting between different members using a solder joint material having a solder material impregnated in a surface or pores of a foam metal material, and the like. 
     Japanese Patent No. 3868766 
     Japanese Laid-Open Patent Publication No. 11-111776 
     Japanese Laid-Open Patent Publication No. 2004-298962 
     “High Acceleration Test of Lead-free Solder” 23rd Spring Lecture Meeting of Japan Institute of Electronics Packaging, March, 2009, 11C-08 
     In the connection between the semiconductor device and the circuit board using bumps, there is a case that stress is generated in the connection portions between the semiconductor device and the circuit board due to thermal expansion and contraction of the semiconductor device and the circuit board connected to each other, and the repetition of generation of stress causes metal fatigue, which sometimes results in breakage of the connection portions. Further, when the semiconductor device and the circuit board are connected using bumps, as the semiconductor device and the circuit board each have a smaller inter-electrode pitch, there is a higher possibility that adjacent ones of the bumps are merged, thereby causing a short circuit (bridge). 
     SUMMARY 
     According to one aspect of the invention, there is provided an electronic device including a circuit board having a first electrode formed on a main surface thereof, a semiconductor device disposed toward the main surface of the circuit board, the semiconductor device having a second electrode formed on a surface thereof opposed to the main surface, and a connection member including a hollow cylindrical member and a conductive member disposed within the hollow cylindrical member, and electrically connecting between the first electrode and the second electrode. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
         FIG. 1  is a diagram illustrating an example of an electronic device; 
         FIG. 2  is a diagram illustrating an example of a connection member; 
         FIGS. 3A and 3B  are diagrams illustrating an example of a method of forming an electronic device; 
         FIGS. 4A and 4B  are diagrams illustrating examples of respective states of the electronic device during downtime and during operation; 
         FIGS. 5A and 5B  are diagrams illustrating another example of the method of forming the electronic device; 
         FIGS. 6A and 6B  are diagrams illustrating an example of a circuit board; 
         FIGS. 7A and 7B  are diagrams illustrating an example of a semiconductor package; 
         FIGS. 8A to 8D  are diagrams illustrating an example of a process step of forming connection members according to a first embodiment; 
         FIGS. 9A to 9C  are diagrams illustrating an example of a process step of connecting the connection members according to the first embodiment; 
         FIGS. 10A and 10B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the first embodiment; 
         FIGS. 11A to 11E  are diagrams illustrating an example of a process step of forming connection members according to a second embodiment; 
         FIGS. 12A to 12C  are diagrams illustrating an example of a process step of connecting the connection members according to the second embodiment; 
         FIGS. 13A and 13B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the second embodiment; 
         FIGS. 14A and 14B  are explanatory diagrams of a connection member according to a third embodiment; 
         FIGS. 15A and 15B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the third embodiment; 
         FIGS. 16A and 16B  are explanatory diagrams of a connection member according to a fourth embodiment; 
         FIGS. 17A and 17B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the fourth embodiment; 
         FIGS. 18A to 18D  are diagrams illustrating an example of a process step of forming connection members according to a fifth embodiment; 
         FIGS. 19A and 19B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the fifth embodiment; 
         FIGS. 20A to 20F  are diagrams illustrating an example of a process step of forming connection members according to a sixth embodiment; 
         FIGS. 21A and 21B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the sixth embodiment; 
         FIG. 22  is a diagram illustrating an example of an electronic device including a cooling structure; 
         FIG. 23  is a diagram illustrating another example of an electronic device including a cooling structure; 
         FIG. 24  is a schematic diagram illustrating an example of electronic equipment; 
         FIGS. 25A and 25B  are diagrams illustrating another example of the semiconductor package (another example  1 ); 
         FIGS. 26A and 26B  are diagrams illustrating still another example of the semiconductor package (another example  2 ); 
         FIGS. 27A and 27B  are diagrams illustrating still another example of the semiconductor package (another example  3 ); 
         FIGS. 28A and 28B  are diagrams illustrating an example of a sample; 
         FIGS. 29A and 29B  are diagrams illustrating an example of a method of forming the sample; 
         FIGS. 30A and 30B  are diagrams illustrating an example of the construction of a bending device for use in a bending test; and 
         FIGS. 31A and 31B  are explanatory diagrams of an example of the bending test. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     Embodiments of the present invention will be explained below with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
       FIG. 1  illustrates an example of an electronic device, and  FIG. 2  illustrates an example of a connection member. The electronic device  1  illustrated in  FIG. 1  includes a circuit board  2 , and a semiconductor device  3 . The circuit board  2  and the semiconductor device  3  are connected to each other using a plurality of connection members  4 . 
     The circuit board  2  has a plurality of electrodes  2   a  formed on a main surface thereof. Although not illustrated here, the electrodes  2   a  are electrically connected to a conductive trace pattern (e.g. traces and vias) provided on the circuit board  2 . 
     The semiconductor device  3  is disposed over the circuit board  2 , and has a plurality of electrodes  3   a  provided on a surface opposed to the surface of the circuit board  2  on which the electrodes  2   a  are formed. Although not illustrated here, each electrode  3   a  is electrically connected to a circuit element (a transistor, a resistance, a capacitor, or the like) provided on the semiconductor device  3 . 
     A semiconductor package including e.g. a semiconductor chip can be used for the semiconductor device  3 . As the semiconductor package, it is possible to use a semiconductor package made by electrically connecting (mounting) a semiconductor chip to a circuit board, such as an interposer, by flip-chip connection, wire bonding or the like, and sealing the semiconductor chip and the circuit board with a sealing resin into a package. 
     The semiconductor device  3  can be applied not only to the semiconductor package formed as described above but also to a semiconductor chip. More specifically, an interposer and a semiconductor chip, for example, are used for the circuit board  2  appearing in  FIG. 1  and the semiconductor device  3  appearing in the same, respectively, and the interposer and the semiconductor chip are connected to each other using the connection members  4 . In this case, it is possible to obtain an electronic device  1  (semiconductor device) which includes the interposer and the semiconductor chip connected to each other using the connection members  4 . 
     The electrodes  2   a  of the above-described circuit board  2  and the electrodes  3   a  of the above-described semiconductor device  3  are formed in advance at respective locations corresponding to each other. The electrodes  2   a  of the circuit board  2  and the electrodes  3   a  of the semiconductor device  3  are electrically connected to each other using the connection members  4 . 
     Referring to  FIG. 2 , each connection member  4  includes a hollow cylindrical member  4   a  and a conductive member  4   b  disposed within the hollow cylindrical member  4   a.    
     For the hollow cylindrical member  4   a  of the connection member  4 , it is possible to use e.g. thin wires  4   aa  formed into a mesh-like shape, as illustrated in  FIG. 2 . Each thin wire  4   aa  may be made of a metal or a resin. For the hollow cylindrical member  4   a , it is also possible to use a metal or resin thin wire formed into a coil, a metal or resin plate or sheet formed into a hollow cylindrical shape, or the like. 
     For the hollow cylindrical member  4   a , it is possible to use a metal containing one or not less than two of copper (Cu), a Cu alloy, nickel (Ni), an iron-nickel (Fe—Ni) alloy, palladium (Pd), a Pd alloy, platinum (Pt), and a Pt alloy. Further, e.g. an aromatic polyamide resin as well can be used for the hollow cylindrical member  4   a.    
     To select a material of the hollow cylindrical member  4   a , a material of the conductive member  4   b  disposed within the hollow cylindrical member  4   a  is taken into account. 
     More specifically, as described hereinafter, when mounting the semiconductor device  3  on the circuit board  2 , the conductive member  4   b  disposed within the hollow cylindrical member  4   a  is melted by being heated and is then solidified, whereby the circuit board  2  and the semiconductor device  3  are connected to each other. As the material of the hollow cylindrical member  4   a , it is desirable to use a heat-resistant material which is difficult to be melted or deteriorated when the conductive member  4   b  is heated to be melted, as described above. 
     Further, as the material of the hollow cylindrical member  4   a , it is desirable to use such a material that the conductive member  4   b  melted by heating can wet, so as to suppress connection failure between the circuit board  2  and semiconductor device  3 . Alternatively, as the material of the hollow cylindrical member  4   a , it is desirable to use a material subjected to surface treatment so as to be wetted by the molten conductive member  4   b.    
     Although in the example illustrated in  FIG. 2 , the hollow cylindrical member  4   a  has a circular shape in cross section, this is not limitative, but it is also possible to use a hollow cylindrical member having an elliptic shape or a polygonal shape in cross section, for the hollow cylindrical member  4   a . Further, the hollow cylindrical member  4   a  is not necessarily required to have a closed cross-sectional shape, but a partially broken shape in cross section can be used as the hollow cylindrical member  4   a.    
     For the conductive member  4   b  disposed within the hollow cylindrical member  4   a  configured as above, there is used a material which has a predetermined conductivity, wets the hollow cylindrical member  4   a , and further has a melting point lower than the heat-resistant temperature of the hollow cylindrical member  4   a . In other words, a material which the conductive member  4   b  wets and is resistant to heat which is not lower in temperature than the melting point of the conductive member  4   b  is used for the hollow cylindrical member  4   a.    
     A metal, for example, can be used for the conductive member  4   b . Examples of the metal for the conductive member  4   b  include solder. Tin-lead (Sn—Pb) solder, for example, can be preferably used as the solder for the conductive member  4   b . In addition, as the solder for the conductive member  4   b , tin-silver-copper (Sn—Ag—Cu) solder, tin-bismuth (Sn—Bi) solder, and the like can be used. 
     The conductive member  4   b  is formed at least on one of the surface(s) (both of the outer and inner surfaces or one of the outer and inner surfaces) of the hollow cylindrical member  4   a  and the inside (the inner space (hollow part)) of the hollow cylindrical member  4   a . When the conductive member  4   b  is formed inside the hollow cylindrical member  4   a , it does not matter even if there remains an empty space within the hollow cylindrical member  4   a.    
     The connection member  4  including the hollow cylindrical member  4   a  and the conductive member  4   b , constructed as above, has e.g. a planar size (diameter) S comparable to that of the electrodes  2   a  and  3   a , and a height T set based on the distance to be secured between the circuit board  2  and the semiconductor device  3  after mounting. 
     The connection member  4  constructed as above is disposed between each electrode  2   a  of the circuit board  2  and an associated one of the electrodes  3   a  of the semiconductor device  3 , and the conductive member  4   b  of the connection member  4  is melted and then solidified, whereby one end of the connection member  4  is connected to the electrode  2   a  and the other end thereof is connected to the associated electrode  3   a . This makes it possible to obtain the electronic device  1 , illustrated in  FIG. 1 , in which the semiconductor device  3  is mounted on the circuit board  2  using the connection members  4 . Even after the semiconductor device  3  is mounted on the circuit board  2 , the connection members  4  each maintain the shape of the hollow cylindrical member  4   a  or a shape similar thereto. 
     When mounting the semiconductor device  3  on the circuit board  2 , it is possible to connect in advance the connection members  4  to the respective electrodes  3   a  of the semiconductor device  3 , place the semiconductor device  3  having the connection members  4  connected thereto over the circuit board  2 , and then melt and solidify the conductive members  4   b.    
     Further, it is possible to form a conductive connection layer (made of a metal, such as solder, solder paste, a conductive resin, or the like) in advance on at least one of each electrode  2   a  and each electrode  3   a , and then connect the connection members  4  to the electrodes  2   a  and  3   a  via the connection layer. 
     By connecting the circuit board  2  and the semiconductor device  3  of the electronic device  1  via the connection members  4  described as above, it is possible to increase the service life of connection portions between the circuit board  2  and the semiconductor device  3 . Further, by using the above-described connection members  4 , it is possible to effectively suppress occurrence of bridges between adjacent ones of the connection portions. Hereinafter, more detailed descriptions will be given of these points. 
     To this end, first, for comparison, a description will be given of an electronic device which has the semiconductor device  3  mounted on the circuit board  2  using solder bumps in place of the above-described connection members  4 . 
       FIGS. 3A and 3B  illustrate an example of a method of forming the electronic device, wherein  FIG. 3A  illustrates a state of the circuit board  2  and the semiconductor device  3  before the semiconductor device  3  is mounted on the circuit board  2 , and  FIG. 3B  illustrates a state of the same after the semiconductor device  3  is mounted on the circuit board  2 . 
     In the example illustrated in  FIG. 3A , each of the solder bumps  110  (solder balls are illustrated in  FIG. 3A , by way of example) is connected to an associated one of the electrodes  3   a  of the semiconductor device  3 . 
     When mounting the semiconductor device  3  on the circuit board  2 , solder pastes  111  are selectively formed on the respective electrodes  2   a  of the circuit board  2 , and the semiconductor device  3  is disposed over the circuit board  2 , as illustrated in  FIG. 3A . Then, the solder bumps  110  and the solder pastes  111  associated therewith, respectively, are heated to the melting temperature thereof, whereby as illustrated in  FIG. 3B , the solder bumps  110  and the solder pastes  111  are merged, and the electrodes  2   a  and  3   a  are electrically connected to each other via respective connection portions  120  formed by the solder bumps  110  and the solder pastes ill merged with each other. At this time, the surface tension of each solder bump  110  and the associated solder paste  111  which are melted and merged with each other is balanced with corresponding part of the weight of the semiconductor device  3  whereby the connection portion  120  is formed into a convex drum shape. 
     In an electronic device  100  using the solder bumps  110  as described above, some of the connection portions  120  are sometimes broken due to heat generated by the semiconductor device  3  after the semiconductor device  3  is mounted on the circuit board  2 . 
       FIGS. 4A and 4B  are diagrams illustrating examples of respective states of the electronic device during downtime and during operation, wherein  FIG. 4A  illustrates an example of the state of the electronic device  100  during downtime, and  FIG. 4B  illustrates an example of the state thereof during operation. 
     Part of heat generated by the semiconductor device  3  during operation of the electronic device  100  is released to the outside, and part thereof conducts inside the electronic device  100  (the semiconductor device  3 , the circuit board  2 , and the connection portions  120  between them). 
     At this time, as illustrated in  FIG. 4B , both the semiconductor device  3  and the circuit board  2  are thermally expanded (in directions indicated by arrows in  FIG. 4B ), but the semiconductor device  3  and the circuit board  2  are different in the degree of thermal expansion depending on the difference between the materials forming them. The difference between the respective degrees of thermal expansion of the semiconductor device  3  and the circuit board  2  generates stresses in the connection portions  120 , which can deform the connection portions  120  each having a fixed shape (convex drum shape), as illustrated in  FIG. 4A , into inclined shapes as illustrated in  FIG. 4B . 
     In the case of the connection portions  120  illustrated in  FIGS. 4A and 4B , portions  120   a  of each connection portion  120  close to the electrodes  2   a  and  3   a  have a thin and narrow shape, and hence stresses are liable to be concentrated on these portions  120   a , which tends to produce cracks  120   b  therein. Further, the portions  120   a  are close to the electrodes  2   a  and  3   a , so that in some cases, inter-metallic compounds are formed between the constituents of the electrodes  2   a  and  3   a  or diffusion of the constituents of the electrodes  2   a  and  3   a  occurs to make the composition of the solder unstable. Therefore, when the electronic device  100  is repeatedly stopped ( FIG. 4A ) and started ( FIG. 4B ), the connection portions  120  are sometimes broken by metal fatigue. Such breakage can be more liable to be caused by an increase in the size of the semiconductor device  3 , making finer the size of the electrodes  2   a  and  3   a  and that of the connection portions  120 , or making finer the pitch between the electrodes  2   a , that between the electrodes  3   a , and that between the connection portions  120 . 
       FIGS. 5A and 5B  illustrate another example of the method of forming the electronic device, wherein  FIG. 5A  illustrates a state of the circuit board  2  and the semiconductor device  3  before the semiconductor device  3  is mounted on the circuit board  2 , and  FIG. 5B  illustrates a state of the same after the semiconductor device  3  is mounted on the circuit board  2 . 
     In the example illustrated in  FIG. 5A , it is assumed that the electrodes  2   a  and the electrodes  3   a  are reduced in pitch. In this case as well, when the semiconductor device  3  is mounted on the circuit board  2  via the solder bumps  110  connected to the semiconductor device  3  and the solder pastes  111  formed on the circuit board  2 , the connection portions  120  are each formed into a convex drum shape with a central bulge, as mentioned hereinabove. However, since the connection portions  120  each have such a convex drum shape, if the electrodes  2   a  and the electrodes  3   a  are reduced in pitch, adjacent ones of the connection portions  120  can be merged with each other to form a bridge  120   c , as illustrated in  FIG. 5B . 
     In contrast, in the electronic device  1  using the connection members  4  illustrated in  FIGS. 1 and 2 , even after the semiconductor device  3  is mounted on the circuit board  2 , each connection member  4  does not have a convex drum shape with a central bulge, but maintains the hollow cylindrical shape which it has before the semiconductor device  3  is mounted on the circuit board  2  or a shape similar to the shape it has before the semiconductor device  3  is mounted on the circuit board  2 . Therefore, the connection members  4  do not have a shape having a narrowed portion at a location close to each of the electrodes  2   a  and  3   a , so that it is possible to prevent stress caused by the difference between the respective degrees of thermal expansion of the semiconductor device  3  and the circuit board  2  from concentrating on portions of the connection members  4  close to the electrodes  2   a  and  3   a . As a result, it is possible to increase the service life of the connection portions of the electronic device  1  that connect between the semiconductor device  3  and the circuit board  2 . 
     Further, since the connection members  4  do not have the convex drum shape after the semiconductor device  3  is mounted on the circuit board  2 , it is possible to effectively suppress occurrence of bridges. This makes it possible to cope with the above-mentioned reduction in pitch between the electrodes  2   a  and between the electrodes  3   a.    
     Hereafter, the electronic device using the above-described connection members will be described in more detail. Now, the description will be given by taking, as an example, a case in which a semiconductor package as a semiconductor device is mounted on the circuit board, using the connection members. 
     First, a description will be given of a first embodiment. 
     In this embodiment, a circuit board illustrated in  FIGS. 6A and 6B  and a semiconductor package illustrated in  FIGS. 7A and 7B  are used. 
       FIGS. 6A and 6B  illustrate an example of the circuit board, wherein  FIG. 6A  is a schematic plan view of the circuit board, and  FIG. 6B  is a schematic cross-sectional view taken on line L 1 -L 1  of  FIG. 6A . Further,  FIGS. 7A and 7B  illustrate an example of the semiconductor package, wherein  FIG. 7A  is a schematic plan view of the semiconductor package, and  FIG. 7B  is a schematic cross-sectional view taken on line L 2 -L 2  of  FIG. 7A . 
     As the circuit board, there is used a circuit board  20  which has a flat square surface and has a predetermined number of electrodes  21  of a predetermined size arranged at a predetermined pitch on the surface, as illustrated in  FIG. 6A . For example, the circuit board  20  has a planar size of 110 mm square and has 420 electrodes  21  with a diameter of 1 mm arranged at a pitch of 1.27 mm on the surface thereof. 
     As illustrated in  FIG. 6B , the circuit board  20  includes an insulating layer  22 , and a conductive trace pattern  23  including traces formed in the insulating layer  22  and vias that connect between different traces. The electrodes  21  are electrically connected to the conductive trace pattern  23  formed within the circuit board  20  constructed as above. The electrodes  21  and the conductive trace pattern  23  are formed using Cu, for example. 
     As illustrated in  FIG. 7A , as the semiconductor package, there is used a semiconductor package  30  which has a square flat surface and has a predetermined number of electrodes  31  of a predetermined size arranged at a predetermined pitch on the surface. For example, the semiconductor package  30  has a planar size of 40 mm square and has 420 electrodes  31  with a diameter of 1 mm arranged at a pitch of 1.27 mm on the surface in association with the respective electrodes  21  of the circuit board  20 . 
     As illustrated in  FIG. 7B , the semiconductor package  30  includes an interposer  32 , and a semiconductor chip  33  which is flip-chip connected to the interposer  32  via bumps  33   a , such as solders. Within the semiconductor chip  33 , there are formed circuit elements, such as transistors, resistances, and capacitors. 
     The interposer  32  includes an insulating layer  32   a , and a conductive trace pattern  32   b  including traces formed in the insulating layer  32   a  and vias that connect between different traces. The electrodes  31  of the semiconductor package  30  are electrically connected to the semiconductor chip  33  via the conductive trace pattern  32   b . The electrodes  31  and the conductive trace pattern  32   b  are formed using Cu, for example. 
     In the present embodiment, the semiconductor chip  33  connected to the interposer  32  is sealed with a sealing resin  34 . 
     In the following, the illustration of the internal construction of the circuit board  20  except for the electrodes  21 , and the illustration of the internal construction of the semiconductor package  30  except for the electrodes  31  are omitted, for convenience sake. 
     Next, a description will be given of a process step of forming connection members connecting between the circuit board  20  and the semiconductor package  30 , constructed as described above. 
       FIGS. 8A to 8D  illustrate an example of a process step of forming connection members according to the first embodiment. 
     First, a sheet-like net  41  is prepared which is made of a mesh of thin wires  41   a , illustrated in  FIG. 8A . Then, the sheet-like net  41  is wound around a core rod  42 , as illustrated in  FIG. 8A , such that it is formed into a hollow cylindrical shape. After that, the core rod  42  is pulled out to obtain a hollow cylindrical (tube-like) net  41  (hollow cylindrical member), as illustrated in  FIG. 8B . 
     In the present embodiment, as the net  41 , it is possible to use a 200 mesh copper net made of thin wires  41   a  having a diameter of 0.05 mm. Further, the core rod  42  may have a diameter of 0.5 mm. When the net  41  and the core rod  42 , thus configured, are used, the  FIG. 8B  hollow cylindrical net  41  obtained after pulling out the core rod  42  has a diameter of approximately 0.8 mm to 0.9 mm, for example. 
     After the hollow cylindrical net  41  is formed as described above, solder  43  as a conductive member is disposed within the net  41 , as illustrated in  FIG. 8C . 
     To dispose the solder  43  within the net  41 , an Sn—Pb (Sn 63%, Pb 37%) string solder  43  containing turpentine is heated to approximately 250° C. to 300° C. while being brought into contact with the hollow cylindrical net  41 . The solder  43  can be melted using e.g. a solder iron or a hot plate set to a predetermined temperature. The molten solder  43  is wet-spread on the surface of the net  41  e.g. by capillary action, and as illustrated in  FIG. 8C , fills the inside of the hollow cylindrical net  41 . 
     Furthermore, it is possible to dispose the solder  43  inside the net  41  by dipping the hollow cylindrical net  41  in a tank containing the molten solder  43 . 
     Further, the hollow cylindrical net  41  having the solder  43  disposed therein can be formed by winding the sheet-like net  41  around the string solder (solder  43 ), or by further heating and melting the string solder of the hollow cylindrical net  41  thus formed. 
     After the solder  43  is disposed within the hollow cylindrical net  41 , the net  41  is cut, as illustrated in  FIG. 8D , to a length based on a distance to be secured between the circuit board  20  and the semiconductor package  30  after the semiconductor package  30  is mounted on the circuit board  20  (the height of each connection portion connecting between the circuit board  20  and the semiconductor package  30 ), e.g. a length corresponding to the distance (e.g. 1 mm). This makes it possible to obtain a plurality of connection members  40  having a predetermined height. 
     Next, a description will be given of a process step of connecting the connection members  40  to the semiconductor package  30  according to the first embodiment. 
       FIGS. 9A to 9C  illustrate an example of the process step of connecting the connection members according to the first embodiment, wherein  FIG. 9A  illustrates a process step of arranging the connection members,  FIG. 9B  illustrates a process step of heating the connection members, and  FIG. 9C  illustrates a state of the connection members after connected to the semiconductor package. 
     First, a rosin-based flux (not illustrated) is applied to the surfaces of the electrodes  31  of the semiconductor package  30 . 
     Then, as illustrated in  FIG. 9A , a mask  51  having holes  51   a  each formed at the same position as that of an associated one of the electrodes  31  is disposed on the semiconductor package  30  after aligning the holes  51   a  with the electrodes  31 , respectively. As the mask  51 , it is possible to use e.g. a metal mask made of Kovar, which has a thickness of 1 mm and has holes  51   a  with a diameter of 1.2 mm formed at a position of the associated one of the electrodes  31 . 
     Then, as illustrated in  FIG. 9A , the connection members  40  are dropped, shaken, and rolled on the mask  51  arranged on the semiconductor package  30 . Thus, as illustrated in  FIG. 9B , the connection members  40  are rolled into the respective openings  51   a , and are disposed on the respective electrodes  31  in an erected state (oriented in a direction in which the hollow cylindrical net  41  is erected). From this state, the connection members  40  are arranged and heated on the hot plate to a temperature at which the solder  43  of each connection member  40  is melted, e.g. 250° C., whereby the molten solder  43  and the associated electrode  31  are connected to each other. 
     Finally, by removing the mask  51 , it is possible to obtain the semiconductor package  30  which has the connection members  40  connected to the associated electrodes  31 , respectively, as illustrated in  FIG. 9C . 
     The connection members  40  can be arranged on the electrodes  31  not only by the above-described method of using the mask  51  but also by a method of using a manufacturing apparatus, such as a solder ball mounting apparatus, and causing the manufacturing apparatus to operate to automatically arrange the connection members  40 , in place of solder balls, on the electrodes  31 . 
     Next, a description will be given of a process step of mounting the semiconductor package  30  on the circuit board  20 , according to the first embodiment. 
       FIGS. 10A and 10B  are diagrams illustrating an example of a process step of mounting the semiconductor package according to the first embodiment, wherein  FIG. 10A  illustrates a state of the circuit board and the semiconductor package before the semiconductor package is mounted on the circuit board, and  FIG. 10B  illustrates a state of the same after the semiconductor package is mounted on the circuit board. 
     After the connection members  40  are connected to the semiconductor package  30  as described above, first, as illustrated in  FIG. 10A , the semiconductor package  30  is brought to a position above the circuit board  20  such that a side having the connection members  40  disposed thereon is opposed to the circuit board  20 , and then the semiconductor package  30  is positioned by aligning the connection members  40  with the electrodes  21 , respectively. 
     Then, in a state where the foremost end of each connection members  40  is brought into abutment with an associated electrode  21 , the solder  43  of each connection member  40  is melted by heating in a nitrogen atmosphere using a reflow furnace set such that the temperature around the connection members  40  becomes equal to 220° C. at the highest. This makes it possible to obtain an electronic device  10 A, illustrated in  FIG. 10B , in which the electrodes  31  of the semiconductor package  30  and the electrodes  21  of the circuit board  20  are connected to each other by the connection members  40 , respectively. 
     In the electronic device  10 A constructed as above, the semiconductor package  30  and the circuit board  20  are connected to each other by the connection members  40  each having the solder  43  disposed within the hollow cylindrical net  41 . Since the connection members  40  are configured as above, even during operation of the electronic device  10 A, it is possible to prevent stress caused by the difference between the degrees of thermal expansion of the semiconductor package  30  and the circuit board  20  from concentrating on portions of the connection members  40  close to the electrodes  21  and  31 . As a result, it is possible to increase the service life of the connection portions of the electronic device  10 A that connect between the semiconductor package  30  and the circuit board  20 . 
     Further, by using the connection members  40  configured as above, it is possible to maintain the cylindrical shape of the connection portions that connect between the semiconductor package  30  and the circuit board  20 , and hence it is possible to effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     Although in the above description, Cu is used as the material of the net  41  of each connection member  40 , by way of example, the material of the net  41  is not limited to this. For example, a metal having a solder wettability to the solder  43 , e.g. a metal comprising one or a combination of two or more of Cu, a Cu alloy, Ni, an Fe—Ni alloy, Pd, a Pd alloy, Pt, and a Pt alloy can be used as the material of the net  41 . 
     Further, although in the above description, the connection members  40  are formed in a flow illustrated in  FIGS. 8A to 8D , by way of example, the method of forming the connection members  40  is not limited to this. For example, a method may be employed in which a long hollow cylindrical net  41  is formed, and then the net  41  is cut off to a predetermined length to dispose the solder  43  within each individual cut-off net  41 . 
     Further, although in the above description, the connection members  40  are formed using the net  41 , by way of example, this is not limitative, but it is possible to replace the net  41  by a hollow cylindrical member formed by rolling a plate member and dispose the solder  43  within the hollow cylindrical member to thereby form connection members. In this case, one end and the other end of the rolled plate are not necessarily required to be in contact with each other, but they may be separate from each other. 
     Further, although in the above description, the connection members  40  are directly connected to the electrodes  21  of the circuit board  20 , by way of example, this is not limitative, but the connection members  40  can be connected to the electrodes  21  by bringing the connection members  40  into abutment with associated ones of the electrodes  21  after forming a conductive connection layer e.g. of solder paste on each electrode  21  by screen printing or a like method. 
     Next, a second embodiment will be described. 
     First of all, a description will be given of a process step of forming connection members according to the second embodiment. 
       FIGS. 11A to 11E  illustrate an example of the process step of forming the connection members according to the second embodiment. 
     Referring to  FIGS. 11A and 11B , first, as described above in the first embodiment, the sheet-like net  41  is wound around the core rod  42 , such that it is formed into a hollow cylindrical shape. After that, the core rod  42  is pulled out to obtain a hollow cylindrical (tube-like) net  41 . 
     Then, as illustrated in  FIG. 11C , dies  60  having a convex surface with a predetermined curvature radius are pushed against the hollow cylindrical net  41  in a manner sandwiching the hollow cylindrical net  41 , and in this state, the hollow cylindrical net  41  is circumferentially rotated (in a direction indicated by arrows in  FIG. 11C ). This makes it possible to obtain a hollow cylindrical net  41  having narrow portions  41   b  formed thereon. In doing this, e.g. stainless (SUS304) dies having a curvature radius R of 1.5 mm can be used as the dies  60 . 
     Positions of the narrow portions  41   b  are set based on the distance to be secured between the circuit board  20  and the semiconductor package  30  after the semiconductor package  30  is mounted on the circuit board (the height of each connection portion connecting between the circuit board  20  and the semiconductor package  30 ). For example, each narrow portion  41   b  is formed such that the distance between bulging portions  41   c  on the opposite sides thereof (e.g. the distance between two adjacent most bulging points of the net  41 ) becomes equal to a distance (e.g. 1 mm) corresponding to the distance to be secured between the circuit board  20  and the semiconductor package  30  after the semiconductor package  30  is mounted on the circuit board  20 . 
     After forming the hollow cylindrical net  41  having the narrow portions  41   b  formed as above, as illustrated in  FIG. 11D , the solder  43  as a conductive member is disposed therein. The disposition of the solder  43  can be performed in the same manner as described above in the first embodiment, i.e. by the method of heating and melting the Sn—Pb (Sn 63%, Pb 37%) string solder  43  containing turpentine while bringing the string solder  43  into contact with the hollow cylindrical net  41 , or the method of dipping the hollow cylindrical net  41  in the tank containing the molten solder  43 , for example. The molten solder  43  is wet-spread on the surface of the hollow cylindrical net  41  having the narrow portions  41   b  formed thereon, and fills the inside of the hollow cylindrical net  41 . 
     It should be noted that after winding the sheet-like net  41  around the string solder (solder  43 ) to form a hollow cylindrical shape, or further heating the string solder to melt the same and then solidifying the molten solder, the solder and the net  41  can be deformed using the dies  60  to form the narrow portions  41   b.    
     After the solder  43  is disposed within the hollow cylindrical net  41  including the narrow portions  41   b , the net  41  having the solder  43  disposed therein is cut through at each bulging portion  41   c , as illustrated in  FIG. 11E . For example, in a case where the narrow portions  41   b  are formed such that the distance between the most bulging points of adjacent bulging portions  41   c  on the opposite sides of one narrow portion  41   b  becomes equal to the distance to be secured between the circuit board  20  and the semiconductor package  30  after the semiconductor package  30  is mounted on the circuit board  20 , the net  41  is cut through at the most bulging points. This makes it possible to obtain a plurality of so-called concave drum shaped connection members  40   a  each having a predetermined height and having the narrow portion  41   b  formed at a central portion thereof. 
     To form such connection members  40   a , there may be employed a method in which after forming a long hollow cylindrical net  41  having the narrow portions  41   b  formed thereon, the hollow cylindrical net  41  is cut off to a predetermined length, and then the solder  43  is disposed within each resultant individual net  41 . 
     Next, a description will be given of a process step of connecting the connection members  40   a  to the semiconductor package  30  according to the second embodiment. 
       FIGS. 12A to 12C  are diagrams illustrating an example of a process step of connecting the connection members according to the second embodiment, wherein  FIG. 12A  illustrates a process step of arranging the connection members,  FIG. 12B  illustrates a process step of heating the connection members, and  FIG. 12C  illustrates a state of the connection members after connected to the semiconductor package. 
     First, fluxes (not illustrated) are formed on the surfaces of the respective electrodes  31  of the semiconductor package  30 . Then, as illustrated in  FIG. 12A , a mask  51  having holes  51   a  each formed at the same position as that of an associated one of the electrodes  31  is arranged on the semiconductor package  30  after aligning the openings  51   a  of the mask  51  with the electrodes  31 , respectively. 
     Then, using the mask  51 , the connection members  40   a  are rolled into the respective openings  51   a  thereof, and are arranged, as illustrated in  FIG. 12B , on the respective electrodes  31  in an erected state (oriented in a direction in which the hollow cylindrical  41  is erected). From this state, the connection members  40   a  are heated to a temperature at which the solder  43  is melted, whereby the molten solder  43  and each electrode  31  are connected to each other. 
     Finally, by removing the mask  51 , it is possible to obtain the semiconductor package  30  which has the connection members  40   a  connected to the electrodes  31 , respectively, as illustrated in  FIG. 12C . 
     Next, a description will be given of a process step of mounting the semiconductor package  30  on the circuit board  20  according to the second embodiment. 
       FIGS. 13A and 13B  illustrate an example of the process step of mounting the semiconductor package according to the second embodiment, wherein  FIG. 13A  illustrates a state of the circuit board  20  and the semiconductor package  30  before the semiconductor package is mounted on the circuit board  20 , and  FIG. 13B  illustrates a state of the same after the semiconductor package  30  is mounted on the circuit board  20 . 
     After the connection members  40   a  are connected to the semiconductor package  30  as described above, first, as illustrated in  FIG. 13A , a side having the connection members  40   a  disposed thereon is caused to be opposed to the circuit board  20 , and the semiconductor package  30  is positioned by aligning the connection members  40   a  with the electrodes  21 , respectively. It should be noted that each electrode  21  of the circuit board  20  may have e.g. solder paste (not illustrated) applied thereto in advance by screen printing or a like method. 
     Then, the foremost end of each connection member  40   a  is brought into abutment with an associated one of the electrodes  21 , and is heated in a nitrogen atmosphere using a reflow furnace set to a predetermined temperature. As a result, an electronic device  10 B, illustrated in  FIG. 13B , can be obtained in which the electrodes  31  of the semiconductor package  30  and the electrodes  21  of the circuit board  20  are connected to each other by the connection members  40   a , respectively. 
     In the electronic device  10 B constructed as described above, the semiconductor package  30  and the circuit board  20  are connected to each other by the respective concave drum shaped connection members  40   a  each having the narrow portion  41   b  formed at a central portion thereof. Therefore, even during operation of the electronic device  10 B, it is possible to prevent stress caused by the difference between the respective degrees of thermal expansion of the semiconductor package  30  and the circuit board  20  from concentrating on the portions of the connection members  40   a  close to the electrodes  21  and  31 . The stress is liable to occur at the narrow portion  41   b  where the composition of the solder  43  is relatively stable. As a result, it is possible to increase the service life of the connection portions between the semiconductor package  30  and the circuit board  20 . 
     Further, by using the above-described connection members  40   a , the connection portions connecting the semiconductor package  30  and the circuit board  20  can each maintain its cylindrical shape with a narrow central portion. This makes it possible to effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     Next, a third embodiment will be described. 
     First, a description will be given of connection members according to the third embodiment. 
       FIGS. 14A and 14B  are explanatory diagrams of the connection member according to the third embodiment, wherein  FIG. 14A  illustrates an example of a hollow cylindrical member, and  FIG. 14B  illustrates an example of the connection member using the hollow cylindrical member in  FIG. 14A . 
     In this embodiment, as the hollow cylindrical member for a connection member  70 , there is used a hollow cylindrical (tube-like) coil  71  (hollow cylindrical member) formed by a spiral of a thin wire  71   a.    
     For the thin wire  71   a  of the coil  71 , it is possible to use a metal wire having a diameter of 0.05 mm, for example. For the thin spiral wire  71   a , it is possible to use a metal wire having wettability to the solder  43 , e.g. a metal wire formed using one or a combination of two or more of Cu, a Cu alloy, Ni, an Fe—Ni alloy, Pd, a Pd alloy, Pt, and a Pt alloy. A coil having a diameter of 0.8 mm to 1 mm and a height of 1 mm can be used as the above-described coil  71 . 
     The connection member  70  is obtained by disposing solder  73  as a conductive member within the coil  71  illustrated in  FIG. 14A , as illustrated in  FIG. 14B . The disposition of the solder  43  within the coil  71  can be performed in the same manner as described above in the first embodiment, i.e. by the method of heating and melting Sn—Pb (Sn 63%, Pb 37%) string solder  73  containing turpentine while bringing the string solder  73  into contact with the coil  71 , or the method of dipping the coil  71  in a tank containing the molten solder  73 , for example. The molten solder  73  is wet-spread on the surface of the coil  71 , and fills the inside of the coil  71 . 
     In the third embodiment, the semiconductor package  30  and the circuit board  20  are connected to each other using the connection members  70  thus obtained. 
       FIGS. 15A and 15B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the third embodiment, wherein  FIG. 15A  illustrates a state of the circuit board  20  and the semiconductor package  30  before the semiconductor package is mounted on the circuit board  20 , and  FIG. 15B  illustrates a state of the same after the semiconductor package  30  is mounted on the circuit board  20 . 
     First, the connection members  70  are connected to the electrodes  31  of the semiconductor package  30 , respectively. Connection of the connection members  70  to the electrodes  31  can be performed in the same manner as described above in the first embodiment ( FIGS. 9A to 9C ). That is, it is only required that by using the mask  51  having the holes  51   a  each formed at the same position as that of an associated one of the electrodes  31 , the connection members  70  are rolled into the respective openings  51   a  to dispose the connection members  70  on the respective electrodes  31 , and the connection members  70  are heated to a temperature at which the solder  73  is melted, to thereby connect the connection members  70  to the electrodes  31 , respectively. After that, the mask  51  is removed. 
     After the connection members  70  are connected to the semiconductor package  30  as described above, as illustrated in  FIG. 15A , a side of the semiconductor package  30  having the connection members  70  disposed thereon is caused to be opposed to the circuit board  20 , and the semiconductor package  30  is positioned by aligning the connection members  70  with the electrodes  21 , respectively. It should be noted that each electrode  21  of the circuit board  20  may have e.g. solder paste (not illustrated) applied thereto in advance by screen printing or a like method. 
     Then, the foremost end of each connection member  70  is brought into abutment with an associated one of the electrodes  21 , and is heated in a nitrogen atmosphere using a reflow furnace set to a predetermined temperature. As a result, an electronic device  10 C, illustrated in  FIG. 15B , can be obtained in which the electrodes  31  of the semiconductor package  30  and the electrodes  21  of the circuit board  20  are connected to each other by the connection members  70 , respectively. 
     In the thus-obtained electronic device  10 C, the connection portions connecting the semiconductor package and the circuit board  20  can each maintain its cylindrical shape, so that it is possible to increase the service life of the connection portions and effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     Next, a fourth embodiment will be described. 
     First, a description will be given of connection members according to the fourth embodiment. 
       FIGS. 16A and 16B  are explanatory diagrams of the connection member according to the fourth embodiment, wherein  FIG. 16A  illustrates an example of a hollow cylindrical member, and  FIG. 16B  illustrates an example of the connection member using the hollow cylindrical member in  FIG. 16A . 
     In this embodiment, as the hollow cylindrical member for a connection member  70   a , a coil  71  is used which is formed by a spiral of a thin wire  71   a  and has a narrow portion  71   b  in a central portion thereof, as illustrated in  FIG. 16A . The connection member  70   a  having the narrow portion  71   b  in the central portion thereof, as illustrated in  FIG. 16B , can be obtained by disposing the solder  73  within the coil  71  illustrated in  FIG. 16A , in the same manner as described above in the third embodiment. 
     In the fourth embodiment, the semiconductor package  30  and the circuit board  20  are connected to each other using the connection members  70   a  obtained as above. 
       FIGS. 17A and 17B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the fourth embodiment, wherein  FIG. 17A  illustrates a state of the circuit board  20  and the semiconductor package  30  before the semiconductor package is mounted on the circuit board  20 , and  FIG. 17B  illustrates a state of the same after the semiconductor package  30  is mounted on the circuit board  20 . 
     First, the connection members  70   a  described above are connected to the respective electrodes  31  of the semiconductor package  30 , similarly to the above-described connection members  70  according to the third embodiment. The semiconductor package  30  having the connection members  70   a  connected thereto is positioned such that it is opposed to the circuit board  20  by performing alignment, as illustrated in  FIG. 17A . 
     Then, the foremost end of each connection member  70   a  is brought into abutment with an associated one of the electrodes  21  (which may have e.g. solder paste (not illustrated) applied thereto), and is heated at a predetermined temperature. As a result, an electronic device  10 D, illustrated in  FIG. 17B , can be obtained in which the electrodes  31  of the semiconductor package  30  and the electrodes  21  of the circuit board  20  are connected to each other by the connection members  70   a , respectively. 
     In the thus-obtained electronic device  10 D as well, the connection portions connecting the semiconductor package  30  and the circuit board  20  can each also maintain its cylindrical shape with a narrow central portion. This makes it possible to increase the service life of the connection portions and effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     Next, a fifth embodiment will be described. 
     First, a description will be given of a process step of forming connection members according to the fifth embodiment. 
       FIGS. 18A to 18D  are diagrams illustrating an example of a process step of forming the connection members according to the fifth embodiment. 
     In the fifth embodiment, a hollow cylindrical (tube-like) resin net  81  (hollow cylindrical member) formed by a mesh of resin-made thin wires (fibers), illustrated in  FIG. 18A , is prepared. An aromatic polyamide resin, for example, can be used for a material of the thin wire of the net  81 . A net having a thickness of 0.05 mm and an inner diameter of approximately 1 mm, for example, can be used for the hollow cylindrical net  81 . 
     A solder  83  (string solder) is inserted into the hollow cylindrical resin net  81 , illustrated in  FIG. 18A , as a conductive member, as illustrated in  FIGS. 18B and 18C . 
     After disposing the solder  83  within the net  81 , the net  81  containing the solder  83  is cut off to a length (e.g. 1 mm) based on the distance to be secured between the circuit board  20  and the semiconductor package  30  after the semiconductor package  30  is mounted on the circuit board  20  (the height of each connection portion connecting between the circuit board  20  and the semiconductor package  30 ). This makes it possible to obtain a plurality of connection members  80  having a predetermined height. 
     Although in the illustrated example, the hollow cylindrical net  81  formed by a mesh of resin-made thin wires is used by way of example, this is not limitative, but a resin-made thin wire formed into a shape of a coil (a hollow cylindrical shape, a shape with a narrow central portion, or the like) can also be used as the hollowing cylindrical member. 
     Further, although in the illustrated example, the connection members  80  are formed using the resin-made net  81 , by way of example, it is also possible to replace the net  81  e.g. by a resin molded article having a hollow cylindrical shape, or a flexible resin sheet rolled into a hollow cylindrical shape, as the cylindrical member. Further, one end and the other end of the rolled sheet are not necessarily required to be in contact with each other, but they may be separate from each other. 
     In the fifth embodiment, the semiconductor package  30  and the circuit board  20  are connected to each other using the above-described connection members  80 , respectively. 
       FIGS. 19A and 19B  are diagrams illustrating an example of a process step of mounting a semiconductor package according to the fifth embodiment, wherein  FIG. 19A  illustrates a state of the circuit board  20  and the semiconductor package  30  before the semiconductor package is mounted on the circuit board  20 , and  FIG. 19B  illustrates a state of the same after the semiconductor package  30  is mounted on the circuit board  20 . 
     First, the connection members  80  are connected to the electrodes  31  of the semiconductor package  30 , respectively. Connection of the connection members  80  to the electrodes  31  can be performed in the same manner as described above in the first embodiment ( FIGS. 9A to 9C ). That is, it is only required that by using the mask  51  having the holes  51   a  each formed at the same position as that of an associated one of the electrodes  31 , the connection members  80  are rolled into the respective openings  51   a  to dispose the connection members  80  on the respective electrodes  31 , and the connection members  80  are heated to a temperature at which the solder  83  is melted, to thereby connect the connection members  80  to the electrodes  31 , respectively. After that, the mask  51  is removed. 
     Then, the semiconductor package  30  having the connection members  80  connected thereto is positioned such that it is opposed to the circuit board  20  by performing alignment, as illustrated in  FIG. 19A . Then, the foremost end of each connection member  80  is brought into abutment with an associated one of the electrodes  21  (which may have solder paste (not illustrated) applied thereto) and is heated to a predetermined temperature. As a result, an electronic device  10 E, illustrated in  FIG. 19B , can be obtained in which the electrodes  31  of the semiconductor package  30  and the electrodes  21  of the circuit board  20  are connected to each other by the connection members  80 , respectively. 
     In the thus obtained electronic device  10 E as well, the connection portions between the semiconductor package  30  and the circuit board  20  can each also maintain its cylindrical shape, whereby it is possible to increase the service life of the connection portions and effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     Next, a sixth embodiment will be described. 
     First, a description will be given of a process step of forming connection members according to the sixth embodiment. 
       FIGS. 20A to 20F  are diagrams illustrating an example of a process step of forming the connection members according to the sixth embodiment. 
     In the sixth embodiment, first, a resin-made sheet  91   a , illustrated in  FIG. 20A , is prepared. As the sheet  91   a , it is possible to use a fabric sheet made of an aromatic polyamide resin (formed by weaving resin thin wires (fibers)), for example. 
     Then, a sheet  91   a  provided with a surface-treated layer  91   b , i.e. a surface-treated sheet  91  is prepared by forming the surface-treated layer  91   b  having wettability to solder  93 , referred to hereinafter, on a surface of the sheet  91   a , as illustrated in  FIG. 20B . As the surface-treated layer  91   b , it is possible to form a layer containing a metal having solder wettability, e.g. metal containing one or a combination of two or more of Cu, a Cu alloy, Ni, an Fe—Ni alloy, Pd, a Pd alloy, Pt, and a Pt alloy. The thickness of the surface-treated layer  91   b  can be set to 0.01 mm, for example. Such a surface-treated layer  91   b  can be formed on the sheet  91   a  e.g. by an electroless plating method. 
     Next, the surface-treated sheet  91  is wound around a core rod  92 , as illustrated in  FIG. 20C , such that it is formed into a hollow cylindrical shape (having a diameter e.g. of 1 mm). After that, the core rod  92  is pulled out to thereby obtain the surface-treated sheet  91  (hollow cylindrical member) which is wound into a hollow cylindrical (tube-like) shape, as illustrated in  FIG. 20D . By virtue of the plastic deformation of the surface-treated layer  91   b  formed on its surface, the surface-treated sheet  91  wound into the hollow cylindrical shape preserves its hollow cylindrical shape even after the core rod  92  is pulled out therefrom. Further, one end and the other end of the surface-treated sheet  91 , which has the core rod  92  pulled out after being wound therearound, are not necessarily required to be in contact with each other, but they may be separate from each other. 
     After forming the surface-treated sheet  91  having the hollow cylindrical shape, the solder  93  as a conductive member is disposed therein, as illustrated in  FIG. 20E . The disposition of the solder  93  can be performed in the same manner as described above in the first embodiment, i.e. by the method of heating and melting the Sn—Pb (Sn 63%, Pb 37%) string solder  93  containing turpentine while bringing the string solder  93  into contact with the surface-treated sheet  91 , or the method of dipping the surface-treated sheet  91  in a tank containing the molten solder  93 , for example. The molten solder  93  is wet-spread on the surface-treated layer  91   b  formed on the surface of the surface-treated sheet  91  having the hollow cylindrical shape, and fills the inside of the surface-treated sheet  91  wound as above. 
     The surface-treated sheet  91 , after having the solder  93  disposed therein, is cut off to a length (e.g. 1 mm) based on the distance to be secured between the circuit board  20  and the semiconductor package  30  after the semiconductor package  30  is mounted on the circuit board  20  (the height of each connection portion connecting between the circuit board  20  and the semiconductor package  30 ), as illustrated in  FIG. 20F . This makes it possible to obtain a plurality of connection members  90  having a predetermined height. 
     In the sixth embodiment, the semiconductor package  30  and the circuit board  20  are connected to each other using the thus obtained connection members  90 . 
       FIGS. 21A and 21B  are diagrams illustrating an example of a process step of mounting the semiconductor package according to the sixth embodiment, wherein  FIG. 21A  illustrates a state of the circuit board  20  and the semiconductor package  30  before the semiconductor package is mounted on the circuit board  20 , and  FIG. 21B  illustrates a state of the same after the semiconductor package  30  is mounted on the circuit board  20 . 
     First, the connection members  90  are connected to the electrodes  31  of the semiconductor package  30 , respectively. Connection of the connection members  90  to the electrodes  31  can be performed in the same manner as described above in the first embodiment ( FIGS. 9A to 9C ). That is, it is only required that by using the mask  51  having the holes  51   a  each formed at the same position as that of an associated one of the electrodes  31 , the connection members  90  are rolled into the respective openings  51   a  to dispose the connection members  90  on the electrodes  31 , respectively, and the connection members  90  are heated to a temperature at which the solder  93  is melted, to thereby connect the connection members  90  to the electrodes  31 , respectively. After that, the mask  51  is removed. 
     Then, the semiconductor package  30  having the connection members  90  connected thereto is positioned such that it is opposed to the circuit board  20  by performing alignment, as illustrated in  FIG. 21A . Then, the foremost end of each connection member  90  is brought into abutment with an associated one of the electrodes  21  (which may have e.g. solder paste (not illustrated) applied thereto) and is heated to a predetermined temperature. As a result, an electronic device  10 F, illustrated in  FIG. 21B , can be obtained in which the electrodes  31  of the semiconductor package  30  and the electrodes  21  of the circuit board  20  are connected to each other by the connection members  90 , respectively. 
     In the thus-obtained electronic device  10 F as well, the connection portions between the semiconductor package  30  and the circuit board  20  can each also maintain its cylindrical shape, so that it is possible to increase the service life of the connection portions and effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     Although the above descriptions have been given of the electronic devices  10 A to  10 F, the electronic devices  10 A to  10 F each can be further provided with a cooling structure (a heat sink). 
       FIG. 22  illustrates an example of an electronic device including a cooling structure. 
     The electronic device  10 G illustrated in  FIG. 22  has, by way of example, a cooling structure  201  including a plurality of fins  201   a  provided on the semiconductor package  30  connected to the circuit board  20  using the connection members  40  described above in the first embodiment. The cooling structure  201  can be formed by a metal material, such as aluminum (Al) or Cu, having excellent thermal conductivity, and is provided on the semiconductor package  30  e.g. via a thermal grease (not illustrated) or an adhesive agent (not illustrated) having a predetermined thermal conductivity. The semiconductor package  30  and the circuit board  20  are thermally connected to each other. 
     By providing such a cooling structure  201 , heat generated in the semiconductor package  30  (not necessarily all the generated heat) is transferred to the cooling structure  201 , and is efficiently released therefrom. As a result, it is possible to effectively suppress an excessive rise in temperature of the semiconductor package  30  and deformation (expansion, contraction, or warpage) of the circuit board  20  and the semiconductor package  30 , thereby making it possible for the electronic device  10 G to stably operate for a long time period. 
     Further,  FIG. 23  illustrates another example of an electronic device including a cooling structure. 
     The electronic device  10 H as illustrated in  FIG. 23  has, by way of example, the cooling structure  202  including a plurality of fins  202   a  provided on the semiconductor package  30  connected to the circuit board  20  using the connection members  40  described above in the first embodiment. The cooling structure  202  can be formed by a metal material, such as Al or Cu, having excellent thermal conductivity, and is provided on the semiconductor package  30  e.g. via a thermal grease (not illustrated) or an adhesive agent (not illustrated) having a predetermined thermal conductivity. 
     The cooling structure  202  is provided with through holes  202   b  through which a plurality of fixing screws  203  extend, respectively. Further, in the illustrated example, the circuit board  20  as well is provided with through holes  20   b  through which the fixing screws  203  extend, respectively. Each fixing screw  203  is inserted through the through holes  202   b  and  20   b , and is screwed into a screw-receiving plate  204  on a side of the circuit board  20  opposite from the semiconductor package  30 . The electronic device  10 H is thus configured such that the cooling structure  202  is firmly fixed using the fixing screws  203 . 
       FIG. 23  illustrates a case where stand-offs  210  are provided between the circuit board  20  and the semiconductor package  30  for maintaining the distance therebetween constant. 
     By using the electronic device  10 H as well, it is possible to effectively suppress an excessive rise in temperature of the semiconductor package  30  and deformation (expansion, contraction, or warpage) of the circuit board  20  and the semiconductor package  30 , thereby making it possible to cause the electronic device  10 H to stably operate for a long time period. 
     Although in the illustrated examples, the semiconductor package  30  is connected to the circuit board  20  using the connection members  40  described above in the first embodiment, by way of example, this is not limitative, but it is possible to dispose the cooling structure  201  or  202  in the electronic devices in which the semiconductor package  30  is connected to the circuit board  20  using the connection members  40   a ,  70 ,  70   a ,  80  and  90  described in the second to sixth embodiments, similarly to the electronic devices illustrated in  FIGS. 22 and 23 . 
     Further, the above-described electronic devices  10 A to  10 F, and electronic devices (electronic devices  10 G,  10 H, etc.) having the cooling structure  201  or  202  provided thereon are applicable to various electronic equipment (electronic devices). 
       FIG. 24  is a schematic diagram illustrating an example of electronic equipment. 
       FIG. 24  illustrates a notebook computer which is one of information processing apparatuses, as electronic equipment  400 , by way of example. The electronic equipment  400  incorporates e.g. the electronic device  10 A in which the semiconductor package  30  is mounted on the circuit board  20  (the connection members  40  are omitted from illustration). In  FIG. 24 , the internal structure of the electronic equipment  400  except for the electronic device  10 A is omitted from illustration. 
     The electronic devices  10 B to  10 H can be applied to the electronic equipment  400  in place of the electronic device  10 A illustrated in  FIG. 24 . Further, although in the example illustrated in  FIG. 24 , the electronic device  10 A or the like is applied to the notebook computer, the electronic device  10 A or the like can be applied to various electronic equipment, such as a desktop computer, a server computer, a semiconductor manufacturing apparatus, and a semiconductor test device. 
     Further, in place of the semiconductor package  30  described above, semiconductor packages constructed as illustrated in  FIGS. 25A to 27B , described hereinafter, can be applied to the above-described electronic devices  10 A to  10 H. 
     A semiconductor package  500 A illustrated in  FIG. 25A  has a construction similar to that of the semiconductor package  30  illustrated in  FIGS. 7A and 7B . More specifically, a semiconductor chip  503  including electrodes  503   b  is flip-chip connected to an interposer  502  including an insulating layer  502   a , a conductive trace pattern  502   b , and electrodes  501   a  and  501   b , via bumps  503   a . The semiconductor chip  503  connected to the interposer  502  is sealed with a sealing resin  504 . 
     On the other hand, a semiconductor package  500 B illustrated in  FIG. 25B  has a structure in which each of the bumps  503   a  of the semiconductor package  500 A is replaced by a connection member  600 . As the connection member  600 , it is possible to use a connection member including a cylindrical member  600   a , and a conductive member  600   b  disposed in the cylindrical member  600   a , as described above. For example, as the connection member  600 , it is possible to use any of the above-described connection members  40 ,  40   a ,  70 ,  70   a ,  80 , and  90 . In this case, the planar size (diameter) of the connection members  40 ,  40   a ,  70 ,  70   a ,  80 , and  90  is set to a size corresponding to the planar size of the electrodes  503   b  of the semiconductor chip  503  and the electrodes  501   b  of the interposer  502 . As illustrated in  FIG. 25B , when the semiconductor chip  503  and the interposer  502  are connected to each other using the connection members  600 , it is possible to prevent stress from concentrating on portions of the connection members  600  close to the electrodes  503   b  and  501   b , whereby it is possible to increase the service life of the connection portions between the semiconductor chip  503  and the interposer  502 . 
     For the above-described electronic devices  10 A to  10 H, it is possible to use not only the semiconductor package  500 A illustrated in  FIG. 25A  but also the semiconductor package  500 B illustrated in  FIG. 25B . 
     Further, a semiconductor package  510 A illustrated in  FIG. 26A  has a structure in which the semiconductor chip  503  flip-chip connected to the interposer  502  via the bumps  503   a  is covered with a metal cover  511 . The metal cover  511  is joined (thermally connected) to the upper surface of the semiconductor chip  503  mounted on the interposer  502 , by a thermal conductive member  512 , such as a thermal grease or an adhesive agent having a predetermined thermal conductivity. Furthermore, the metal cover  511  has an edge thereof joined to the upper surface of the interposer  502  using an adhesive material  513 . In the case of the electronic devices  10 G and  10 H provided with the cooling structure  201  or  202 , the cooling structure  201  or  202  is provided on the metal cover  511  using e.g. the thermal grease or the adhesive agent having a predetermined thermal conductivity. In this case, heat generated in the semiconductor chip  503  (not necessarily all the generated heat) is transferred e.g. to the thermal conductive member  512  and the metal cover  511 , and is then transferred to the cooling structure  201  or  202 , for being released therefrom. 
     On the other hand, a semiconductor package  510 B illustrated in  FIG. 26B  has a structure in which each of the bumps  503   a  of the semiconductor package  510 A illustrated in  FIG. 26A  is replaced by a connection member  600 . For example, as the connection member  600 , it is possible to use any of the connection members  40 ,  40   a ,  70 ,  70   a ,  80 , and  90  having a predetermined size depending on the size of the electrodes  503   b  and  501   b . Also when the metal cover  511  illustrated in  FIG. 26B  is used, the semiconductor chip  503  and the interposer  502  are connected to each other using the connection members  600 , whereby it is possible to prevent stress from concentrating on portions of the connection members  600  close to the electrodes  503   b  and  501   b  to increase the service life of the connection portions. Furthermore, by connecting the semiconductor chip  503  and the interposer  502  using the above-described connection members  600 , it is possible to maintain the shape of each connection section to effectively suppress occurrence of bridges between adjacent ones of the connection portions. 
     For the above-described electronic devices  10 A to  10 H, it is also possible to use the semiconductor package  510 A in  FIG. 26A  or the semiconductor package  510 B in  FIG. 26B . 
     Further, semiconductor packages  520 A and  520 B illustrated in  FIGS. 27A and 27B , respectively, are distinguished from the respective semiconductor packages  510 A and  510 B illustrated in  FIGS. 26A and 26B , respectively, in that connection portions between the interposer  502  and the semiconductor chip  503  are sealed with a sealing resin  521 . By providing such a sealing resin  521 , it is possible to further enhance the strength of connection between the interposer  502  and the semiconductor chip  503 . 
     For the above-described electronic devices  10 A to  10 H, it is also possible to use the semiconductor package  520 A in  FIG. 27A  or the semiconductor package  520 B in  FIG. 27B . 
     In the above, the descriptions have been given of the connection between the semiconductor package  30  and the circuit board  20  using the connection members  40 ,  40   a ,  70 ,  70   a ,  80 , and  90 , and the connection between the semiconductor chip  503  and the interposer  502  using the connection members  600 . Next, a description will be given of an example of a method of evaluating reliability of the connections, and an example of the results of evaluation of the connection reliability by the method. 
     As the method of evaluating reliability of the connections, there is used a heat cycle test performed by repeatedly raising and lowering the temperature of a mounting structure in which a semiconductor device, such as a semiconductor package or a semiconductor chip, is flip-chip connected to a substrate, such as a circuit board or an interposer, within a predetermined temperature range. Further, there is also used a method of evaluating the connection reliability of the mounting structure by a bending test which repeatedly generates mechanical stress on the mounting structure. Here, a description will be given of the evaluation of the connection reliability by the bending test. 
     First, a description will be given of an example of the mounting structure (sample) used in the bending test. 
       FIGS. 28A and 28B  are diagrams illustrating an example of a sample, wherein  FIG. 28A  is a plan view of the sample and  FIG. 28B  is a side view of the same. 
       FIGS. 28A and 28B  illustrate a sample  700  in which a semiconductor package  720  is mounted on a circuit board  710 . As the circuit board  710  and the semiconductor package  720 , it is possible to use not only a circuit board and a semiconductor package which can be sold as products but also a circuit board and a semiconductor package which are produced for test purposes based on the respective designs of the products. 
     Here, the circuit board  710  having a planar size of 110 mm square, and the semiconductor package  720  having a planar size of 40 mm square are used, by way of example. The circuit board  710  and the semiconductor package  720  have electrodes  711  and  721  arranged at positions corresponding to each other on opposed surfaces thereof, respectively. The electrodes  711  and  721  each have a diameter of 0.76 mm, for example, and  520  of both of them are arranged on the respective opposed surfaces of the circuit board  710  and the semiconductor package  720  at a pitch of 1.27 mm. Out of the large number of electrodes  711  and  721  opposed to each other, only electrodes  711  and  721  arranged at four corners of the circuit board  710  and the semiconductor package  720  are connected by connection members  730 , respectively. 
     Two leads  712 , and terminals  713  arranged at respective ends of the two leads  712 , are electrically connected to an associated one of the electrodes  711  arranged at the respective four corners of the circuit board  710 . On the other hand, two leads  722  arranged on a surface of the semiconductor package  720 , opposite from the electrodes  721 , and terminals  723  arranged at respective ends of the two leads  722  are electrically connected to an associated one of the electrodes  721  arranged at the respective four corners of the semiconductor package  720  via a via  724  and an electrode  725 . 
     The connection members  730  connecting between the electrodes  711  at the four corners of the circuit board  710  and the electrodes  721  at the four corners of the semiconductor package  720  can be formed, for example, by winding a 200 mesh copper net having a diameter of 0.05 mm around a metal wire having a diameter of 0.3 mm, then pulling out the metal wire to obtain a hollow cylindrical net, and disposing solder within the hollow cylindrical net. It is possible to use e.g. Sn—Pb solder as the solder. Further, the disposition of the solder within the hollow cylindrical net can be performed in the same manner as described above in the first embodiment. When such a metal wire or a net is used, a member obtained after the disposition of the solder has a diameter of approximately 0.6 mm to 0.7 mm. By cutting off the thus obtained member to a length e.g. of 2 mm, separate connection members  730  are formed, and by using the connection members  730 , the sample  700  having the semiconductor package  720  mounted on the circuit board  710  is formed. 
       FIGS. 29A and 29B  are diagrams illustrating an example of a method of forming a sample, wherein  FIG. 29A  illustrates a state of the sample before the semiconductor package  720  is mounted on the circuit board  710 , and  FIG. 29B  illustrates a state of the same after the semiconductor package  720  is mounted on the circuit board  710 . 
     When mounting the semiconductor package  720  on the circuit board  710 , first, the connection members  730  are connected to the electrodes  721  at the four corners of the semiconductor package  720 , respectively. This connection of the connection members  730  can be performed e.g. as follows: 
     Fluxes are formed on the surfaces of the respective electrodes  721  of the semiconductor package  720 , and a mask having openings formed at the respective positions of the electrodes  721  at the four corners of the semiconductor package  720  is disposed on the semiconductor package  720  after aligning the openings with associated ones of the electrodes  721  at the four corners. As the mask, it is possible to use e.g. a metal mask made of Kovar, having a thickness of 1 mm to 2 mm. Then, the connection members  730  are rolled into the openings of the mask to dispose them on the respective electrodes  721  at the four corners of the semiconductor package  720 , in an erected state (oriented in a direction in which the hollow cylindrical net is erected). From this state, the connection members  730  are heated to a temperature at which the solder is melted, whereby the molten solder and the electrodes  721  are connected to each other. Finally, the mask used for rolling the connection members  730  is removed, whereby it is possible to obtain the semiconductor package  720  in which the connection members  730  are connected to the associated electrodes  721  at the four corners of the semiconductor package  720 , respectively. 
     On the other hand, as for the circuit board  710 , a mask, e.g. a metal mask having a thickness of 0.15 mm, which has openings formed at the respective positions of the electrodes  711  at the four corners of the circuit board  710 , is disposed on the circuit board  710  after aligning the openings with associated ones of the electrodes  712  at the four corners. Then, a solder paste  714  is printed on the electrodes  711  at the four corners, as illustrated in  FIG. 29A . As the solder paste  714 , it is possible to use the Sn—Pb solder, for example. 
     As illustrated in  FIG. 29A , the semiconductor package  720  having the connection members  730  connected thereto is brought to a position above the circuit board  710  printed with the solder paste  714 , as described above, such that a side of the semiconductor package  720  having the connection members  730  connected thereto is opposed to the circuit board  710 , and is then positioned by performing alignment. Then, the foremost ends of the connection members  730  are brought into contact with the solder paste  714  on the electrodes  711 , and are heated in a nitrogen atmosphere using a reflow furnace set such that the temperature around the connection members  730  becomes equal to 220° C. at the highest to thereby melt the solder of the connection members  730  and the solder paste  714 . This makes it possible to obtain the sample  700  in which the electrodes  711  at the four corners of the circuit board  710  and the associated electrodes  721  at the four corners of the semiconductor package  720  are connected to each other by the connection members  730 , respectively, as illustrated in  FIG. 29B . 
     The bending test is performed on the sample  700  thus obtained to thereby evaluate the connection reliability of connection portions between the circuit board  710  and the semiconductor package  720 . Here, for comparison, the bending test is performed on a sample (comparative sample) in which the electrodes  711  at the four corners of the circuit board  710  and the associated electrodes  721  at the four corners of the semiconductor package  720  are connected to each other by solder bumps formed by solder balls, respectively, for evaluation of the connection reliability of the comparative sample. 
       FIGS. 30A and 30B  are diagrams illustrating an example of the construction of a bending device for use in the bending test, wherein  FIG. 30A  is a plan view of essential elements of the bending device, and  FIG. 30B  is a side view of the essential elements. Further,  FIGS. 31A and 31B  are explanatory diagrams of an example of the bending test, wherein  FIG. 31A  illustrates a first state of the bending test, and  FIG. 31B  illustrates a second state thereof.  FIGS. 30A and 30B  and  FIGS. 31A and 31B  illustrate the sample  700  using the connection members  730 , by way of example. 
     As illustrated in  FIGS. 30A and 30B  and  FIGS. 31A and 31B , the bending device  800  for use in the bending test comprises a support stand  801 , pushers  802 , a controller  803 , a breakage detection section  804 , and a display section  805 . 
     The support stand  801  includes a pair of support sections  801   a  which are arranged such that they can support unidirectionally opposite edges  710   a  of the circuit board  710  having the semiconductor package  720  mounted thereon, and fixing sections  801   b  for fixing the opposite edges  710   a  of the circuit board  710  to the support sections  801   a . The circuit board  710  having the semiconductor package  720  mounted thereon is placed on the support sections  801   a  of the support stand  801  with the semiconductor package  720  facing toward the support stand  801 , and is fixed to the support sections  801   a  by the fixing sections  801   b.    
     As illustrated in  FIGS. 30A and 30B  and  FIGS. 31A and 31B , the foremost ends of the pushers  802  are configured to be capable of holding respective opposite edges  710   b  of the circuit board  710  placed on the support stand  801 , which are opposite in a direction orthogonal to a direction in which the opposite edges  710   a  are opposite to each other. As illustrated in  FIGS. 31A and 31B , the pushers  802  are configured to vertically move toward and away from the support stand  801  while holding the opposite edges  710   b  of the circuit board  710  with the foremost ends thereof. The vertical motion of the pushers  802  is performed at a predetermined amplitude and a predetermined frequency. The vertical motion of the pushers  802  performed at the predetermined amplitude and the predetermined frequency is controlled by the controller  803 . The bending device  800  is configured such that the conditions (amplitude and frequency) for the vertical motion of the pushers  802  can be set in advance in the bending device  800 . The controller  803  causes the pushers  802  to vertically move according to the set conditions. 
     In the bending test using the bending device  800 , first, the position of the pushers  802  holding the circuit board  710  fixed to the support stand  801  before the start of the bending test is set as a reference position. From the reference position, the pushers  802  are pushed toward the support stand  801  by a predetermined amount ( FIG. 31A ), and then the pushers  802  are returned again to the original reference position ( FIG. 31B ). The motion of the pushers  802  that are pushed from the reference position and are returned again to the original reference is set as one cycle. In the illustrated example, under a temperature environment of room temperature (approximately 25° C.), the one-cycle motion of the pushers  802  that are pushed from the reference position toward the support stand  801  by 1.5 mm and are returned again to the original reference position is performed at a frequency of 0.5 Hz. 
     When the above-described bending test by the pushers  802  is performed, stress is generated in the connection portions between the circuit board  710  and the semiconductor package  720 , and eventually, the connection portions are broken by metal fatigue. The stress generated at the connection portions connecting the circuit board  710  and the semiconductor package  720  is liable to increase in the connection portions at the four corners, implemented using the connection members  730  or the solder bumps. Here, as to only the connection portions at the four corners, where such large stress is liable to occur, the liability (or difficulty) of occurrence of breakage, i.e. the connection reliability is evaluated using the sample  700  using the connection members  730  and the comparative example using the solder bumps. 
     During the bending test, breakage of the connection portions between the circuit board  710  and the semiconductor package  720  can be detected by causing electric current to flow through each of the connection portions at the four corners and monitoring a change in voltage (electric resistance) caused by the electric current. The detection of the breakage of each connection portion can be performed by a four-terminal method, using the leads  712  and  722 , the terminals  713  and  723 , the via  724  and the electrode  725 , formed in advance on the circuit board  710  and the semiconductor package  720 . 
     For example, in the case of the sample  700 , illustrated in  FIGS. 28A and 28B , in which the connection members  730  are used, first, electric current is caused to flow between one of two pairs of the leads  712  and terminals  713  connected to the associated electrode  711  and one of the two pairs of the leads  722  and terminals  723  connected to the associated electrode  721  via the via  724  and the electrode  725 . For example, 160 mA of direct current is caused to flow between the terminals  713  and  723 . Then, voltage between the other of the two pairs of the leads  712  and terminals  713  connected to the electrode  711  and the other of the two pairs of the leads  722  and terminals  723  connected to the electrode  721  is measured. Also in the case of the comparative sample using the solder bumps, similarly to the case of the sample  700 , electric current is caused to flow to measure voltage. 
     Electric current caused to flow through each connection portion between the circuit board  710  and the semiconductor package  720 , and electric resistance determined from voltage measured at the connection portion are monitored, whereby breakage of the connection portion is detected based on the value of the electric resistance. For example, a time point (the number of cycles of vertical motion of the pushers  802 ) when the electric resistance of a connection portion increases by 1% with respect to an initial monitoring value (initial value) of the electric resistance is judged to be a time point when the breakage of the connection portions is detected. 
     Such detection of breakage is performed on each of the respective connection portions at the four corners of the circuit board  710  and the semiconductor package  720 , during the bending test, illustrated in  FIGS. 31A and 31B , by using the bending device  800 , illustrated in  FIGS. 30A and 30B . In doing this, the breakage detection section  804  performs control of the electric current flowing through the connection portions, measurement of voltage of the electric current, calculation and monitoring of the electric resistance as time elapses based on the electric current and voltage, and detection (determination) of breakage of a connection portion based on the value of the electric resistance. Further, the number of cycles of vertical motion of the pushers  802 , controlled by the controller  803 , is supplied to the breakage detection section  804 . Information (electric current, voltage, electric resistance, etc.) on the detection of breakage of a connection portion, obtained by the breakage detection section  804 , is displayed on the display section  805  in association with the number of cycles of vertical motion of the pushers  802 , controlled by the controller  803 . 
     The bending test was performed on the connection portions between the circuit board  710  and the semiconductor package  720  under the above-described conditions, using the comparative sample in which the solder bumps are used and the sample  700  in which the connection members  730  are used. As a result, in the comparative sample in which the solder bumps are used, breakage of a connection portion thereof occurred at the time of a 142-nd cycle. On the other hand, in the sample  700  in which the connection members  730  are used, breakage of a connection portion thereof occurred at the time of a 926-th cycle. When the connection members  730  are used for the connection portions between the circuit board  710  and the semiconductor package  720 , the fatigue life of the connection portions becomes not less than 6.5 times longer than when the solder bumps are used for the connection portions. Therefore, by using the connection members  730 , it is possible to enhance the connection reliability of the connection portions between the circuit board  710  and the semiconductor package  720 . 
     According to the above-mentioned bending test, the connection reliability of the connection portions connecting between the circuit board  710  and the semiconductor package  720  can be evaluated more appropriately in a shorter time period than by the heat cycle test. 
     The conditions for the bending test are not limited to the above-described example. For example, the conditions (amplitude and frequency) of the motion of the pushers  802  can be set as appropriate depending on the materials of the circuit board  710 , the semiconductor package  720 , and the connection members  730 . 
     Further, in the above-described example, a criterion for determining the breakage of a connection portion between the circuit board  710  and the semiconductor package  720  is set to a time point when the electric resistance of the connection portion increases by 1% from the initial value thereof. Such a criterion for determining the breakage of a connection portion can be set as appropriate based on the materials of the circuit board  710 , the semiconductor package  720 , and the connection members  730 , or the degree of required connection reliability. 
     Further, in the above-described example, the case is taken as an example, where the bending test is performed by connecting only the electrodes  711  and  721  at the four corners of the circuit board  710  and the semiconductor package  720  using the connection members  730  or the solder bumps. Instead of this, it is also possible to carry out the bending test by connecting between all the electrodes  711  of the circuit board  710  and all the electrodes  721  of the semiconductor package  720  using the connection members  730  or the like. In this case, the circuit board  710  and the semiconductor package  720  are more firmly connected to each other, so that although it takes a longer time to detect breakage of any of the connection portions, it is possible to evaluate the connection reliability of the connection portions based on an actual form of products or under conditions closer to the actual form of the products. 
     The evaluation of the connection reliability by the above-mentioned bending test can similarly be applied to the evaluation of the connection reliability of the connection portions between the semiconductor chip and the interposer. 
     According to the disclosed electronic device, it is possible to suppress breakage of the connection portions between the circuit board and the semiconductor device, and occurrence of bridges between adjacent ones of the connection portions. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present invention has(have) been described in detail, it should be understood that various changes, substitutions and alterations could be made hereto without departing from the spirit and scope of the invention.