Abstract:
A method for mounting a semiconductor device, which can decrease the occurrence rate of failures, a method for repairing a semiconductor device, which can easily repair defective solder joints, and a semiconductor device which makes those methods feasible. 
     A substrate  1  has formed therein through-holes  7  lined on the internal walls with a wiring layer  9 , and solder balls  6  are fusion-bonded to the substrate  1  in such a manner as to cover the through-holes  7 . In the mounting process or in the repair process, heating probes  41  are passed through the through-holes  7  and thrust into the solder balls  6  to thereby melt the solder balls, and the heating probes are pulled out of the solder balls to let the solder balls cool down. In those processes, only the solder balls  6  can be heated, thereby averting adverse effects on the IC chip  3 . In the repair process, the solder balls  6  can be restored to an initial condition free of intermetallic compounds.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a semiconductor device of ball grid array package (BGA) structure, a method for mounting the semiconductor device, and a method for repairing the semiconductor device. 
     PRIOR ART 
       FIG. 26  is a sectional view schematically showing a conventional semiconductor device of BGA structure of a cavity down type. 
     As shown in  FIG. 26 , the conventional semiconductor device comprises a substrate  101  having an electric wiring circuit formed therein, and a heat slug  102  formed by a copper sheet or the like glued by an adhesive to a periphery of a center opening of the substrate  101 . The conventional semiconductor device comprises an IC chip glued by an adhesive to the heat slug, a metal thin line  104  electrically connecting the IC chip  103  and wiring on the substrate  101 , a sealant  105 , such as an epoxy resin, for sealing the IC chip  103  and the metal thin line  104 , and solder balls  106  as external terminals arrayed in lattice form on one surface (the lower surface of the substrate  101  in  FIG. 26 ) opposite to the other surface of the substrate where the heat slug  102  is provided. The substrate  101  has multiple insulating substrates stacked up one on top of another. In the example in  FIG. 1 , the substrate  101  has three insulating substrates  111 ,  112  and  113 . In addition, the substrate  101  includes a wiring layer  114  pinched by the insulating substrate  111 ,  112  and  113 , and conductors  115  for electrically connecting the wiring layer  114  and solder balls  106 . 
       FIG. 27  is an explanatory diagram showing a process of mounting the semiconductor device shown in FIG.  26 . 
     As shown in  FIG. 27 , in the mounting process of a conventional semiconductor device, solder paste, not shown, composed of minute solder particles and an activator (a flux) is applied to solder balls  106  on the semiconductor device. The solder balls  106  are placed on terminals, not shown, on a mother board  121 , which is a printed circuit board. The solder balls  106  are fused to the terminals on the mother board  121  by heating with a heater place  131  from the underside of the mother board  121  and also circulating a hot air  132  between the mother board  121  and the semiconductor device. 
     Incidentally, in the mounting process of a semiconductor of BGA structure, mounting-induced faults sometimes occur. For example, as shown in  FIG. 28 , owing to temperature changes after a semiconductor device is mounted (chiefly temperature changes with passage of time that take place at temperatures not higher than 150 centigrade), it sometimes occurs that, at solder joints, a layer of an intermetallic compound  106   a  (AuSnNi for example) is formed by Sn from the solder balls  106  and Au and Ni from the terminals of the semiconductor device and the terminals of the mother board. Intermetallic compound layers, such as this  106   a,  tend to increase in thickness with the passage of time. Because the intermetallic compound  106   a  is a brittle substance, due to a difference in thermal expansion coefficient between the substrate  101  and the mother board  121 , stress concentrates at a solder joint, with the result that a crack  135  may occur at the solder joint as shown in FIG.  29 ( a ) or if the crack develops, the solder joint may separate from the terminal  133  as indicated by  136  in FIG.  29 ( b ). 
     Semiconductor devices rejected in a performance test in the production stage or semiconductor devices in which a failure occurred after shipment from factory are subjected to a repair process. An ordinary repair method is carried out in a manner similar to the mounting process shown in FIG.  27 . In other words, after the solder balls  106  are heated, the semiconductor device is detached, the residual solder on the mother board  121  is removed, and a new semiconductor device is mounted. 
     However, in the mounting process of a conventional semiconductor device, the solder balls  106  are heated by the hot air  132 . Therefore, the moisture, absorbed by the substrate  101  and also by the adhesive and the sealant resin  105  at temperature in the process, expands, sometimes giving rise to a blowout called the popcorn phenomenon. If this phenomenon occurs, there is a possibility that the sealant cracks or the chip separates from the sealant. 
     In the conventional semiconductor-device repair method, the semiconductor device as the repair object is removed from the mother board and is replaced by a new semiconductor device. A problem here is that the detached semiconductor device is not reutilized and is discarded. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to solve the above-mentioned problem of the prior art and has as its object to provide a method for mounting a semiconductor device, which can reduce the occurrence rate of semiconductor device failures, such as the popcorn phenomenon mentioned above, and provide a semiconductor device that makes this mounting method viable. 
     Another object of the present invention is to provide a semiconductor device repair method for easily repairing a failure of the solder joint in a semiconductor device without changing the semiconductor device, and also provide a semiconductor device that makes this repair method feasible. 
     According to the present invention, there is provided a semiconductor device provided with a semiconductor chip and a substrate, the substrate has a first wiring layer electrically connected to the semiconductor chip and also has a surface with a terminal, comprising:
         a solder ball connected to the terminal;   a through-hole adjacent to the first wiring layer, the through-hole goes through the substrate and extends to the solder ball through the terminal; and   a second wiring layer extending from the first wiring layer along an internal wall of the through-hole to the terminal, the second wiring layer electrically connects between the first wiring layer and the terminal.       

     A heat conductor with heat conductivity, one end of the heat conductor is connected to the solder ball and the other end of the heat conductor is capable of coming into contact with an external heat generating mechanism, may be provided at each through-hole. 
     The semiconductor device according to the present invention, wherein the through-hole provided to the substrate may be formed so as to extend from a surface other than a surface opposite to the surface having the terminal to the solder ball. 
     The semiconductor device according to the present invention, wherein the substrate may be a multilayer substrate formed by stacking a plurality of insulating substrates and said first wiring layer. 
     The semiconductor device according to the present invention, wherein the terminal may have an opening that matches an opening of the through-hole in shape. 
     The semiconductor device according to the present invention, wherein the terminal may have an opening that makes an opening of the through-hole semi-circular in shape. 
     The semiconductor device according to the present invention, wherein the terminal may have a plurality of fan-shaped openings, each pair of fan-shaped openings being symmetrical with respect to a point. 
     The semiconductor device according to the present invention, wherein the terminal may have an opening located at a center of an opening of the through-hole, which is smaller than the opening of the through-hole. 
     The semiconductor device according to the present invention may further comprises, in the through-hole, a conductor having electrical conductivity, the conductor makes the through-hole semi-cylinder in shape. 
     The semiconductor device according to the present invention may further comprises, in the through-hole, a filler having elasticity and non-heat-conductivity, the filler fills up the through-hole. 
     According to the present invention, there is provided a method for mounting a semiconductor device on a printed circuit board, having a semiconductor chip, a substrate having a first wiring layer electrically connected to the semiconductor chip and also having a surface with a terminal, a solder ball connected to the terminal, a through-hole adjacent to the first wiring layer, the through-hole goes through the substrate and extends to the solder ball through the terminal, and a second wiring layer extending from the first wiring layer along an internal wall of the through-hole, the second wiring layer electrically connects between the first wiring layer and the terminal, the method comprising the steps of:
         placing the semiconductor device on the printed circuit board through the solder ball;   inserting a hot heating probe into the through-hole from a surface of the substrate opposite to the surface with the terminal and thrusting the solder ball with the probe in order to melt the solder ball; and   pulling the probe out from the solder ball in order to solidify the solder ball.       

     According to the present invention, there is provided a method for repairing a semiconductor device placed on a printed circuit board and to be joined to the board with solder, the semiconductor device has a semiconductor chip, a substrate having a first wiring layer electrically connected to the semiconductor chip and also having a surface with a terminal, a solder ball connected to the terminal, a through-hole adjacent to the first wiring layer, the through-hole goes through the substrate and extends to the solder ball through the terminal, and a second wiring layer extending from the first wiring layer along an internal wall of the through-hole, the second wiring layer electrically connects between the first wiring layer and the terminal, comprising the steps of:
         inserting a hot heating probe into the through-hole from a surface of the substrate opposite to the surface with the terminal and thrusting the solder ball with the probe in order to melt the solder ball; and   pulling the probe out from the solder ball in order to solidify the solder ball.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view schematically showing the upper surface (with the heat slug  2 ) of a semiconductor device according to a first embodiment of the present invention; 
         FIG. 2  is a sectional view schematically showing a section S 2 —S 2  of the semiconductor device according to the first embodiment; 
         FIG. 3  is a plan view schematically showing a lower surface of the semiconductor device according to the first embodiment; 
         FIG. 4  is a plan view showing on an enlarged scale a through-hole and its vicinity at the upper surface of the semiconductor device according to the first embodiment; 
         FIG. 5  is a sectional view showing on an enlarged scale the joint between a terminal and a solder ball of the semiconductor device according to the first embodiment; 
         FIG. 6  is an explanatory diagram of a repair process (step  1 ) of the semiconductor device according to the first embodiment mounted on the mother board; 
         FIG. 7  is an explanatory diagram of the repair process (step  2 ) of the semiconductor device according to the first embodiment mounted on the mother board; 
         FIG. 8  is an explanatory diagram of the repair process (step  3 ) of the semiconductor device according to the first embodiment mounted on the mother board; 
       FIG.  9 ( a ) is an explanatory diagram showing the state of a solder ball before execution of the repair process according to the first embodiment; 
       FIG.  9 ( b ) is an explanatory diagram showing the state of a solder ball after execution of the repair process according to the first embodiment; 
         FIG. 10  is a sectional view schematically showing a semiconductor device to which the mounting method of the first embodiment is applied; 
         FIG. 11  is an explanatory diagram of a process (part  1 ) of mounting a semiconductor device according to the first embodiment on the mother board; 
         FIG. 12  is an explanatory diagram of the process (step  2 ) of mounting the semiconductor device according to the first embodiment on the mother board; 
         FIG. 13  is an explanatory diagram of the process (step  3 ) of mounting the semiconductor device according to the first embodiment on the mother board; 
         FIG. 14  is a sectional view showing a semiconductor device according to a modification of the first embodiment; 
       FIG.  15 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a second embodiment of the present invention; 
       FIG.  15 ( b ) is a sectional view showing on an enlarged scale the through-hole and its vicinity of the semiconductor device according to the second embodiment of the present invention; 
       FIG.  16 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device as a modification of the second embodiment; 
       FIG.  16 ( b ) is a plan view showing on an enlarge scale the through-hole and its vicinity of the semiconductor device as the modification of the second embodiment; 
       FIG.  17 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a third embodiment of the present invention; 
       FIG.  17 ( b ) is a plan view showing the terminal of the semiconductor device according to the third embodiment; 
       FIG.  18 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a fourth embodiment of the present invention; 
       FIG.  18 ( b ) is a plan view showing the terminal of the semiconductor device according to the fourth embodiment; 
       FIG.  19 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a fifth embodiment of the present invention; 
       FIG.  19 ( b ) is a plan view showing the terminal of the semiconductor device according to the fifth embodiment; 
         FIG. 20  is a sectional view schematically showing a semiconductor device according to sixth embodiment of the present invention; 
         FIG. 21  is a sectional view schematically showing a modification of the sixth embodiment; 
         FIG. 22  is a sectional view schematically showing another modification of the sixth embodiment; 
         FIG. 23  is a sectional view schematically showing a semiconductor device according to a seventh embodiment of the present invention; 
         FIG. 24  is a sectional view schematically showing a modification of the seventh embodiment; 
         FIG. 25  is a sectional view schematically showing another embodiment of the present invention; 
         FIG. 26  is a sectional view schematically showing the structure of a conventional semiconductor device; 
         FIG. 27  is an explanatory diagram for illustrating a process for mounting a conventional semiconductor device; 
         FIG. 28  is an explanatory diagram for explaining a problem of the conventional semiconductor device; 
       FIG.  29 ( a ) is a sectional view showing a crack of the solder joint in the conventional semiconductor device; and 
       FIG.  29 ( b ) is a sectional view showing a separation of the solder joint in the conventional semiconductor device. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     &lt;First Embodiment&gt; 
     &lt;The Structure of Semiconductor Device in the First Embodiment&gt; 
       FIG. 1  is a plan view schematically showing the upper surface (with a heat slug  2 ) of a semiconductor device according to a first embodiment of the present invention.  FIG. 2  is a sectional view schematically showing a plane taken along the S 2 —S 2  line of the semiconductor device in  FIG. 1 , and  FIG. 3  is a plan view schematically showing the lower surface (with solder balls  6 ) of the semiconductor device in FIG.  1 .  FIG. 4  is a plan view showing on an enlarged scale a through-hole  7  and its vicinity on the upper surface of the semiconductor device in  FIG. 1 , and  FIG. 5  is a sectional view showing on an enlarged scale a joint between a terminal  8  and a solder ball  6  of the semiconductor device in FIG.  1 . 
     As shown in  FIGS. 1  to  3 , the semiconductor device according to the first embodiment has a substrate  1 , in which electric circuits have been formed. In the example illustrated, the substrate  1  includes three insulating substrates  11 ,  12  and  13  stacked one on top of another and a wiring layer  14  as a first wiring layer, pinched by the insulating substrates  11 ,  12  and  13 . The number of the insulating substrates is not limited to three and its sectional profile of the insulating substrates is not limited to rectangular. 
     As shown in  FIG. 2 , the semiconductor device according to the first embodiment includes a heat slug  2  of copper, for example, glued by an adhesive to the periphery of a center opening  1   a  in the upper surface  1   c  (top surface in  FIG. 2 ) of the substrate  1 , an IC chip  3  glued by an adhesive to the heat slug  2 , metal thin lines  4  electrically connecting the IC chip to the wires of the substrate  1  (in other words, bonding wires), a sealant  5  of epoxy resin, for example, for sealing the IC chip  3  and the metal thin lines  4 , and a plurality of solder balls  6  as external terminals arranged in lattice form on the lower surface (bottom surface in  FIG. 2 ) of the substrate  1  opposite to the upper surface  1   c.  The semiconductor device according to the first embodiment has a cavity-down type structure with improved heat radiation properties, but may have another structure, such as a cavity-up type. The solder balls are not limited to the array and the number as shown in FIG.  3 . 
     As shown in  FIG. 2 , the semiconductor device according to the first embodiment has through-holes  7  formed in the substrate  1  so as to go through the upper surface  1   c  and the lower surface  1   b,  and wiring layers  9  as second wiring layers, shown in  FIG. 4 , which go along the internal walls of the through-holes to connect to terminals  8  at the lower surface  1   b.  The through-holes  7  may be formed by punching or reaming with a drill. Each terminal  8  has a structure having a Cu layer, a Ni layer and an Au layer stacked in this order as viewed from the substrate  1 , and has an opening matching in shape with the opening of the through-hole  7 . The wiring  9  is a Cu wiring layer formed by a plating process, for example. As shown in  FIG. 5 , the solder balls  6  are fused to the terminals  8 , and are attached to the lower surface  1   b  of the substrate  1 , thus covering the through-holes  7 . The fusion of the solder ball  6  to the terminal  8  is carried out by the following sequence: an activated flux is applied to the terminal  8 , and on top of that, the solder ball  8  is placed, and heat is applied. 
     In  FIG. 2 , the through-holes  7  extend perpendicularly to the surface of the substrate  1 , but those holes  7  may be tilted with respect to the surface of the substrate  1 . The through-holes  7  may be provided in any direction or shape so long as heating probes  41  of heating devices  40 , which will be described later, can pass through the through-holes  7  and contact the solder balls  6 . 
     &lt;Repair Method of Semiconductor Device in the First Embodiment&gt; 
       FIGS. 6 ,  7  and  8  are explanatory diagrams for explaining the repair process (step  1 ˜ 3 ) according to the first embodiment of the semiconductor device mounted on the mother board  21 , which is a printed circuit board. FIGS.  9 ( a ) and  9 ( b ) are explanatory diagrams respectively showing the states of the solder ball  6  before and after the execution of the repair process. 
     The semiconductor device, to which the repair method according to the first embodiment is applied, is a semiconductor device which has the solder balls  6  of the semiconductor device attached and fused to the terminals  22  ( FIG. 9 ) of the mother board  21  as shown in FIG.  6 . Semiconductor devices which are to be repaired are those which were rejected in a performance test at the production stage, and those which turned out to be defective after they were shipped. 
     In the repair method according to the first embodiment, heating devices  40  are used to heat the solder balls  6  as shown in FIG.  6 . The heating device  40  includes a heat generator  42  that holds proximal ends  41   b  of heating probes  41 , and a moving mechanism  43  for moving the heat generator  42  in horizontal and vertical directions. The heating probe  41  is preferably formed by a material of better thermal conductivity. Materials suitable for the heating probes  41  are metals, such as copper, silver, and platinum, or copper alloys, such as Zr—Cu, Fe—Cu, and Ni—Cu, or iron alloys, such as a 42-alloy (42% Ni—Fe). In the example shown in  FIG. 6 , the distal ends  41   a  of the heating probes  41  are saliently pointed, but may be formed with a spherical head or a flat head. 
     Description will be made of a repair method according to the first embodiment. The heating probes  41  of the heating devices shown in  FIG. 6  are heated. The heating temperature may be set at a predetermined temperature within a range of about 180 to 350 centigrade according to the composition, for example, of the solder balls  6 , but preferably about 240 centigrade. The heating probes  41 , after set at a predetermined temperature, lowered from above the through-holes  7  of the semiconductor device, inserted into the through-holes  7 , thrust into the solder balls  6  as shown in  FIG. 7 , and the solder balls  6  are thereby melted. 
     After this, as shown in  FIG. 8 , the heating probes  41  of the heating devices  40  are pulled out of the solder balls  6  and the solder balls are made to solidify. 
     By the repair method described above, the intermetallic compound layers  6   a  of the solder ball  6 , as shown in FIG.  9 ( a ), are eliminated as is clearly shown in FIG.  9 ( b ). Accordingly, defective solder joints between the solder balls  6  and the terminals  8  or  22  are eradicated which result from the presence of brittle intermetallic compound layers  6   a.    
     Note that if the amount of solder in the solder balls  6  is decreased by actions of thrusting or extracting the heating probes  41 , granular or molten solder may be added from the through-holes  7  of the upper surface  1   c  before the heating probes  41  are inserted. 
     According to the repair method of the first embodiment, the failures at the joints of the solder balls  6  of the semiconductor device can be repaired easily and semiconductor devices having such failures need not be changed. Another advantage is that only the solder balls  6  are heated by the heating probes  41 , with the result that the other component parts of the semiconductor device, the IC chip, above all else, are not adversely affected by high temperature during heating. 
     &lt;Mounting Method of Semiconductor Device in First Embodiment&gt; 
       FIG. 10  is a sectional diagram schematically showing the semiconductor device to which the mounting method according to the first embodiment is applied. 
     Semiconductor devices, for which the mounting method according to the first embodiment is applicable, are those, in which flux was applied to the terminals  8  on the substrate  1 , on top of that, the solder balls  6  were placed, and when they were passed through a heating furnace, not shown, the solder balls  6  were partially melted at the surface and were thereby fusion-bonded to the terminals  8 . 
       FIGS. 11 ,  12  and  13  are explanatory diagrams of the process (steps  1 ˜ 3 ) for mounting the semiconductor device to the mother board  21 . 
     In the method for mounting a semiconductor device according to the first embodiment, the same heating devices  40  as are used in the above-mentioned repair method are used. The mounting method of the first embodiment is as follows. As shown in  FIG. 11 , flux, not shown, is applied to the solder balls  6  of the semiconductor device and the semiconductor balls  6  are placed on the mother board  21 . Then, the heating probes  41  of the heating devices  40  are heated to a predetermined temperature similar to that in the repair method, and lowered from above the through-holes  7  of the semiconductor device, inserted into the through-holes  7 , and as shown in  FIG. 12 , and thrust into the solder balls  6 , which are thereby melted. After this, as shown in  FIG. 13 , the heating probes  41  of the heating devices  40  are pulled out of the solder balls  6 , and the solder balls  6  are made to solidify. 
     By this process, the solder balls  6  are soldered to the terminals of the mother board  21 . 
     If the amount of solder is decreased by actions of thrusting and extracting the heating probes  41 , granular or molten solder may be added from the upper side of the through-holes  7  before the heating probes  41  are inserted. 
     According to the mounting method of the first embodiment, only the solder balls  6  are heated by the heating probes  41 , the other component parts (particularly, the IC chip  3 ) are not negatively-affected during heating. Therefore, the failure occurrence rate of semiconductor devices can be reduced. 
     &lt;Modification of First Embodiment&gt; 
       FIG. 14  is a sectional view showing a modification of the first embodiment. In this semiconductor device, each through-hole  7  is filled with a filling material  15 . For the filling material  15 , it is possible to use materials which have elasticity and non-heat-conductivity, like gel resins which do not exhibit fluidity after the through-hole  7  is filled, such as a silicon-based resin “JCR6110” by Toray Industries, Inc. or a polyimide-based resin “PIX8200” by Hitachi Chemical Co., Ltd. The filled portion  15  is formed by injecting a gel resin from the upper side of the openings of the through-holes  7 . As shown in  FIG. 14 , by the provision of the filled portion  15  in the through-hole  7 , it is possible to prevent failures ascribable to corrosion, for example, of the joint between the terminal  8  and the solder ball  6 , and also preclude the occurrence of failures resulting from the infiltration of foreign matter into the through-holes  7  from outside. 
     By the way, in the repair process of the semiconductor device shown in  FIG. 14 , the heating probe  41  is thrust into the filled portion  15 , and further thrust into the solder ball  6 , and subsequently the heating probe is pulled out. If the gel resin is decreased during the repair process, a gel resin can be replenished as one thinks fit from the opening of the through-hole  7 . 
     &lt;Second Embodiment&gt; 
     FIG.  15 ( a ) is a sectional view schematically showing the through-hole and its vicinity of the semiconductor device according to a second embodiment of the present invention. FIG.  15 ( b ) is a plan view showing the through-hole and the vicinity on an enlarged scale. 
     The difference from the semiconductor device according to the first embodiment is that an electrode  16  as an electrical conductor is formed in the shape of a semi-circular column within the through-hole  7  in the semiconductor device of the second embodiment. For forming the conductor made by an electrode material  16 , it is possible to adopt a method of manufacturing a semicircular column part, setting this column part in each through-hole of the substrate  1 , and forming an electrode  16  that fills up the clearance between the column part and the through-hole  7 , and then extracting the semi-circular electrode  16 . According to the semiconductor device of the second embodiment, the electrode  16  is additionally connected to the solder ball  6 , the bond area with the solder joint  6  is increased, and therefore the bond strength of the solder ball  6  is improved. 
     The repair method and the mounting method of the semiconductor device according to the second embodiment are the same as those in the first embodiment. 
     FIG.  16 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device as a second embodiment of the present invention, and FIG.  16 ( b ) is a plan view showing on an enlarged scale the through-hole and its vicinity of the semiconductor as the second embodiment of the present invention. 
     The only difference from the semiconductor device shown in  FIG. 15  is that a filler  17  of a gel resin is provided that fills up the through-hole  7  of semi-cylindrical structure as shown in FIG.  16 . Note that the material and the role of the filler  17  are the same as those of the filler in the first embodiment. 
     &lt;Third Embodiment&gt; 
     FIG.  17 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a third embodiment of the present invention, and FIG.  17 ( b ) is a plan view showing the terminal  31  of the substrate  1 . 
     The only difference from the semiconductor device of the first embodiment is that a semi-cylindrical opening  31   a  is provided in the terminal  31  as shown in FIG.  17 ( b ) in the semiconductor device in the third embodiment. According to the semiconductor device of the third embodiment, the bond area between the solder ball  6  and the terminal  31  is increased and the bond strength of the solder ball is increased. 
     The repair method and the mounting method of the semiconductor device according to the third embodiment are the same as those in the first embodiment. 
     A filler of gel resin may be provided that fills up the through-hole of the semiconductor device according to the third embodiment. 
     FIG.  18 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a fourth embodiment of the present invention, and FIG.  18 ( b ) is a plan view showing the terminal  32  of the substrate  1 . 
     The difference of the fourth embodiment from the first embodiment is that an opening  32   a  is provided at the terminal  32 , which is located at the center of the through-hole  7  and which has a smaller diameter than the inside diameter of the through-hole. According to the semiconductor device of the fourth embodiment, the bond area between the solder ball  6  and the terminal  32  can be increased and the bond strength of the solder ball  6  can be increased. Moreover, when the heating probe  41  is thrust into the solder ball  6 , the heating probe  41  is guided by the opening  32   a  of the terminal  32  to about the center of the solder ball  6 , and therefore the solder ball  6  can be heated uniformly, thereby ensuring a good bonded state of the solder joint after the mounting or repair process. Furthermore, the opening  32   a  of the terminal  32  may be tapered such that the diameter becomes gradually smaller along the path of the opening from the through-hole  7  to the solder ball  6 , by which the positioning of the heating probe  41  with respect to the solder ball  6  can be made easier. 
     The repair method and the mounting method of the semiconductor device according to the fourth embodiment are the same as those in the first embodiment. 
     A filler of gel resin may be provided that fills up the through-hole  7  of the semiconductor device of the fourth embodiment. 
     &lt;Fifth Embodiment&gt; 
     FIG.  19 ( a ) is a sectional view schematically showing a through-hole and its vicinity of a semiconductor device according to a fifth embodiment of the present invention, and FIG.  19 ( b ) is a plan view showing the terminal  33  of the substrate. 
     In the semiconductor device of a fifth embodiment, its difference from the semiconductor device of the first embodiment is that the terminal  33  has a cruciform portion  33   a  as shown in FIG.  19 ( b ), for which reason the terminal  33  has four fan-shaped openings  33   b.  According to the semiconductor device according to the fifth embodiment, the bond area between the solder ball  6  and the terminal  33  is increased, and the higher bond strength of the solder ball  6  can be secured. Further, each pair of the bond areas between the terminal  33  and the solder ball  6  is symmetrical with respect to a point, so the bond strength of the joint is made higher and stable. 
     The repair method and the mounting method of the semiconductor device according to the fifth embodiment are the same as those in the first embodiment. The heating probe  41  is passed through the opening  33   b  and thrust into the solder ball  6 . 
     In the through-hole  7  of the semiconductor device of the fifth embodiment, a filler of gel resin may be provided to fill up the through-hole. 
     &lt;Sixth Embodiment&gt; 
       FIG. 20  is a sectional view schematically showing a semiconductor device according to a sixth embodiment of the present invention. 
     The only difference of the sixth embodiment from the semiconductor device of the first embodiment is that fixed probes  44  of heat-conducting material are provided so as to protrude above the upper surface  1   c  in order that one end of each fixed probe  44  is in contact with the solder ball  6  and the other end is capable of contacting a heat generating part  51  of an external heating unit. The fixed probes  44  are previously inserted into the through-holes  7 , and can be ground to have the same height. The fixed probes  44  are preferably formed by a material with good heat conductivity. Suitable materials for this purpose are metals, such as copper, silver and platinum, copper alloys, such as Zr—Cu, Fe—Cu and Ni—Cu, or iron alloys, including 42-alloy (42% Ni—Fe). 
     The repair method and the mounting method of the semiconductor device according to the sixth embodiment are as follows. The heating part  51  (a panel type for example) of an external heating unit is heated and brought into contact with end portions  44   a  of the fixed probes  44  to heat the solder balls  6 . In this heating, the heat generating part  51  may first be brought into contact with the solder balls  6  and then heated. After the solder balls  6  are made molten by the heating described above, the heat generating part  51  of the heating unit is detached from the end portions  44   a  of the fixed probes  44  (or, heat-generation is stopped) to cool the solder balls  6 . 
     According to the sixth embodiment, the solder balls  6  can be heated uniformly. In the mounting process, flux, not shown, is applied to the solder balls  6  of the semiconductor device, and those solder balls  6  are put on the terminals on the mother board  21 , and then the fixed probes  44  are heated by the heat generating part  51  of the heating unit. 
     In other respects except for what was described above, the sixth embodiment is the same as the first embodiment. 
     A filler of gel resin may be provided to fill up the gap between the wiring layer and the fixed probe  44  in each through-hole of the semiconductor device of FIG.  20 . 
       FIG. 21  is a sectional view schematically showing a modification of the semiconductor device of the sixth embodiment of the present invention. 
     The semiconductor device as a modification shown in  FIG. 21  differs from the semiconductor device as the sixth embodiment shown in  FIG. 20  in that the end faces  45   a  of the fixed probes  45  are flush with the surface  1   c  of the substrate. In this modification, protrusions, which can contact the end faces  45   a  of the fixed probes  45 , are provided on the heat generating part  52  of the heating unit. 
       FIG. 22  is a sectional view schematically showing another modification of the semiconductor device of the sixth embodiment of the present invention. 
     The semiconductor device as a modification shown in  FIG. 22  differs from the semiconductor device as the sixth embodiment shown in  FIG. 20  in that the end faces  46   a  of fixed probes  46  are lower than the surface  1   c  of the substrate  1 . In this modification, protrusions, which can contact the end faces  46   a  of the fixed probes  46 , are provided on the heat generating part  53  of the heating unit. 
     &lt;Seventh Embodiment&gt; 
       FIG. 23  is a sectional view schematically showing the semiconductor device according to a seventh embodiment of the present invention. 
     The differences of the semiconductor device of the seventh embodiment from the semiconductor device of the first embodiment are that as shown in  FIG. 23 , through-holes  60  are formed in the substrate  1  so as to run from the lower surface  1   b  to the side face  1   d  of the substrate  1 , and that fixed probes  61  of heat conducting material are provided in the through-holes  60 , the fixed probes being joined at one end to the solder balls  6  and protruding at the other end from the side face  1   d  so as to be able to contact the heat generating part, not shown, of an external heating unit. For the method for manufacturing fixed probes  61 , it is possible to use a method of pinching a copper plate material between the insulating substrates in the manufacture process of the substrate  1 . The probes  61  are preferably formed by a material of better heat conductivity. Materials suitable for the fixed probes  61  are metals, such as copper, silver and platinum, copper alloys, such as Zr—Cu, Fe—Cu and Ni—Cu, or iron alloys, such as 42-alloy (42% Ni—Fe). 
     In the repair method and the mounting method of the semiconductor device according to the seventh embodiment, after a heat generator part, not shown, of a heating unit is heated, the heat generator part is brought into contact with the end portions  61   a  of the fixed probes  61  (or the heat generator is first brought into contact with the fixed probes and then heated), to thereby heat the solder balls  6 . After this, by separating the heat generator part of the heating unit from the end portions  61   a  of the fixed probes (or by turning off the heating), the solder balls  6  are cooled down. 
     According to the seventh embodiment, the solder balls  6  can be heated uniformly. Because the fixed probes  61  can be heated from the side faces  1   d  of the substrate  1 , the so-called three-dimensional mounting is made possible, by which the structure of the semiconductor device is expanded in the height direction. In the mounting process, flux, not shown, is applied to the solder balls  6  of the semiconductor device, the solder balls  6  are put on the terminals of the mother board  21 , and then the fixed probes  61  are heated by the heat generating part of the heating unit. 
     In other respects except for what was described above, the seventh embodiment is the same as the first embodiment. 
     A filler of gel resin may be provided to fill up the gap between the through-hole  7  and the fixed probe  61  as shown in FIG.  23 . 
       FIG. 24  is a sectional view schematically showing a modification of the semiconductor device according to the seventh embodiment of the present invention. 
     The semiconductor device as a modification shown in  FIG. 24  differs from the semiconductor device as the seventh embodiment in  FIG. 23  in that the end faces  62   a  of the fixed probes  62  are flush with the side faces  1   d  of the substrate  1 . In this modification, protrusions that can contact the end faces  62   a  of the fixed probes  62  need to be provided on the heat generator body of the heating unit. 
       FIG. 25  is a sectional view schematically showing another modification of the semiconductor device according to the seventh embodiment of the present invention. 
     The semiconductor device as a modification shown in  FIG. 25  differs from the semiconductor device shown in  FIG. 23  in that the end faces  63   a  of the fixed probes  63  are retracted from the side faces  1   d  of the substrate  1 . In this modification, protrusions, which can contact the end faces of the fixed probes  63  need to be provided on the heat generating part of the heating unit. 
     According to the semiconductor device according to the present invention, the occurrence rate of failures attending on mounting of semiconductor devices can be reduced. 
     Further, according to the semiconductor device of the present invention, failures in the solder joints of semiconductor devices can be repaired easily, making it unnecessary to replace semiconductor devices having failures at their solder joints. 
     Further, if the through-holes of the semiconductor device according to the present invention are filled with fillers, it is possible to prevent deterioration of the solder joints resulting from penetration of foreign substances. 
     Further, if fixed probes as heat conductors are used to fill up the through-holes of the semiconductor device according to the present invention, the structure of the heating unit to heat the solder balls can be simplified. 
     Further, if the end portions of the fixed probes are exposed on the side faces of the substrate, three-dimensional mounting becomes possible by which semiconductor substrates are stacked one upon another. 
     According to the mounting method of the semiconductor device of the present invention, the occurrence rate of failures attending on mounting of semiconductor devices can be decreased. 
     According to the repair method of the semiconductor device of the present invention, the defective solder joints can be repaired easily and semiconductor devices having such failures need not be changed.