Abstract:
In a ball grid array type semiconductor device including an interposer substrate having first and second surfaces, a semiconductor chip mounted on the first surface of the interposer substrate, and solder balls formed on the second surface of the interposer substrate, a plurality of through holes are formed within the interposer substrate, and each of the solder balls clogs one of the through holes of the interposer substrate.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a ball grid array (BGA) type semiconductor device and its manufacturing method. Particularly, it relates to the improvement of a repairing method of defective solder generated when the BGA type semiconductor device is mounted on a motherboard.  
           [0003]    2. Description of the Related Art  
           [0004]    Since BGA type semiconductor devices (packages) can have a larger number of external terminal pins as compared with quad flat packages (QFPs) and small outline packages (SOPs), such BGA type packages have recently been developed.  
           [0005]    In a prior art method for manufacturing a BGA type semiconductor device, a semiconductor chip is mounted on a first surface of an interposer substrate. On the other hand, solder balls are provided on a second surface of the interposer substrate. As a result, the semiconductor chip is electrically connected via through holes having a relatively small diameter provided in the interposer substrate to the solder balls. Next, the BGA semiconductor device is mounted on a motherboard by soldering the solder balls thereto. This will be explained later in detail.  
           [0006]    In the above-described method, an open state or a short-circuit state may be generated due to the defective soldering process. In order to repair the open state or the short-circuit state, the interposer substrate is separated and detached from the motherboard by a heating process using hot air blown via through holes provided within the motherboard  4  (see JP-A-9-181404) or by a special local heating process using hot air blown via nozzles provided at the periphery of the BGA type semiconductor device (see JP-A-11-26929). Then, the surface of the motherboard is cleaned, and solder paste is again adhered thereto. Finally, a new BGA type semiconductor device is mounted on the motherboard. Note that BGA type semiconductor devices including such defective solder balls are usually discarded. Thus, the manufacturing cost is increased.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of the present invention to decrease the manufacturing cost of BGA type semiconductor devices.  
           [0008]    According to the present invention, in a BGA type semiconductor device including an interposer substrate having first and second surfaces, a semiconductor chip mounted on the first surface of the interposer substrate, and solder balls formed on the second surface of the interposer substrate, a plurality of through holes are formed within the interposer substrate, and each of the solder balls clogs one of the through holes of the interposer substrate. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The present invention will be more clearly understood from the description set forth below, as compared with the prior art, with reference to the accompanying drawings, wherein:  
         [0010]    [0010]FIGS. 1A and 1B are cross-sectional views illustrating a prior art method for manufacturing a BGA type semiconductor device;  
         [0011]    [0011]FIGS. 2A and 2B are cross-sectional views for explaining defective soldering states of the BGA type semiconductor device of FIG. 1B;  
         [0012]    [0012]FIGS. 3A and 3B are cross-sectional views illustrating a first embodiment of the method for manufacturing a BGA type semiconductor device according to the present invention;  
         [0013]    [0013]FIGS. 4A and 4B are cross-sectional views for explaining defective soldering states of the BGA type semiconductor device of FIG. 3B; and  
         [0014]    [0014]FIGS. 5A and 5B are cross-sectional views illustrating a second embodiment of the method for manufacturing a BGA type semiconductor device according to the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    Before the description of the preferred embodiments, a prior art method for manufacturing a BGA type semiconductor device will be explained with reference to FIGS. 1A and 1B.  
         [0016]    First, referring to FIG. 1A, a semiconductor chip  1  is mounted on a first surface of an interposer substrate  2 . In this case, the semiconductor chip  1  can be of a flip-chip type. On the other hand, solder balls  3   a  and  3   b  are provided on a second surface of the interposer substrate  2 . The semiconductor chip  1  is electrically connected via through holes  2   a  and  2   b  having a relatively small diameter such as 0.3 mm provided in the interposer substrate  2  to the solder balls  3   a  and  3   b , respectively. Note that metal layers (not shown) are formed within the through holes  2   a  and  2   b.    
         [0017]    Next, referring to FIG. 1B, the BGA semiconductor device of FIG. 1A is mounted on a motherboard  4  by soldering the solder balls  3   a  and  3   b  thereto.  
         [0018]    In the method as illustrated in FIGS. 1A and 1B, an open state or a short-circuit state may be generated due to the defective soldering process. For example, as illustrated in FIG. 2A, the solder ball  3   a  is disconnected from the motherboard  4 , which shows an open state. On the other hand, as illustrated in FIG. 2B, the solder ball  3   a  is electrically connected to the solder ball  3   b , which shows a short-circuit state.  
         [0019]    In order to repair the open state as illustrated in FIG. 2A or the short-circuit state as illustrated in FIG. 2B, in the prior art, the interposer substrate  2  is separated and detached from the motherboard  4  by a heating process using hot air blown via through holes provided within the motherboard  4  (see JP-A-9-181404) or by a special local heating process using hot air blown via nozzles provided at the periphery of the BGA type semiconductor device (see JP-A-11-26929). Then, the surface of the motherboard  4  is cleaned, and solder paste is again adhered thereto. Finally, a new BGA type semiconductor device is mounted on the motherboard  4 . This would increase the manufacturing cost.  
         [0020]    Note that BGA type semiconductor devices including such defective solder balls are usually discarded.  
         [0021]    A first embodiment of the method for manufacturing a BGA type semiconductor device according to the present invention will be explained next with reference to FIGS. 3A and 3B.  
         [0022]    First, referring to FIG. 3A, a semiconductor chip  1  is mounted on a first surface of an interposer substrate  2 . In this case, the semiconductor chip  1  can be of a flip-chip type. On the other hand, solder balls  3   a  and  3   b  are provided on a second surface of the interposer substrate  2 . The semiconductor chip  1  is electrically connected via through holes  2   a ′ and  2   b ′ having a relatively large diameter such as 0.5 mm provided in the interposer substrate  2  to the solder balls  3   a  and  3   b , respectively. In this case, the solder balls  3   a  and  3   b  are provided so as to clog the through holes  2   a   40  and  2   b ′, respectively. Also, metal layers (not shown) are formed within the through holes  2   a ′ and  2   b′.    
         [0023]    Next, referring to FIG. 4B, the BGA semiconductor device of FIG. 4A is mounted on a motherboard  4  by soldering the solder balls  3   a  and  3   b  thereto.  
         [0024]    Even in the method as illustrated in FIGS. 3A and 3B, an open state or a short-circuit state may be generated due to the defective soldering process. For example, as illustrated in FIG. 4A, the solder ball  3   a  is disconnected from the motherboard  4 , which shows an open state. On the other hand, as illustrated in FIG. 4B, the solder ball  3   a  is electrically connected to the solder ball  3   b , which shows a short-circuit state.  
         [0025]    In order to repair the open state solder ball  3   a  in FIG. 4A, melted solder is added by using a special tool via the through hole  2   a ′ onto the solder ball  3   a  as indicated by an arrow, so that the solder ball  3   a  can be in touch with the motherboard  4 . Thus, the solder ball  3   a  can be repaired without separating and detaching the interposer substrate  2  from the motherboard  4 , which would decrease the manufacturing cost.  
         [0026]    In order to repair the short-circuited solder balls  3   a  and  3   b  in FIG. 4B, the solder balls  3   a  and  3   b  are sucked by using a special tool as indicated by arrows. Then, melted solder is injected by using a special tool into the through holes  2   a ′ and  2   b ′, so that new solder balls can be in touch with the motherboard  4 . Thus, the short-circuited solder balls  3   a  and  3   b  can be repaired without separating and detaching the interposer substrate  2  from the motherboard  4 , which would decrease the manufacturing cost.  
         [0027]    A second embodiment of the method for manufacturing a BGA type semiconductor device according to the present invention will be explained next with reference to FIGS. 5A and 5B.  
         [0028]    First, referring to FIG. 5A, resin layers  5   a  and  5   b  are formed in advance within through holes  2   a ′ and  2   b ′ of an interposer substrate  2 . Then, a semiconductor chip  1  is mounted on a first surface of the interposer substrate  2 . In this case, the semiconductor chip  1  can be of a flip-chip type. On the other hand, solder balls  3   a  and  3   b  are provided on a second surface of the interposer substrate  2 . The semiconductor chip  1  is electrically connected via through holes  2   a ′ and  2   b ′ having a relatively large diameter such as 0.5 mm provided in the interposer substrate  2  to the solder balls  3   a  and  3   b , respectively. In this case, the solder balls  3   a  and  3   b  are provided so as to clog the through holes  2   a ′ and  2   b ′, respectively. Also, metal layers (not shown) are formed within the through holes  2   a ′ and  2   b′.    
         [0029]    Next, referring to FIG. 5B, the BGA semiconductor device of FIG. 4A is mounted on a motherboard  4  by soldering the solder balls  3   a  and  3   b  thereto.  
         [0030]    The resin layers  5   a  and  5   b  serve as means for supporting the solder balls  3   a  and  3   b . Therefore, if the BGA semiconductor device of FIG. 5A is relatively heavy, the solder balls  3   a  and  3   b  cannot penetrate the through holes  2   a ′ and  2   b ′, respectively, due to the presence of the resin layers  5   a  and  5   b.    
         [0031]    Even in the method as illustrated in FIGS. 5A and 5B, an open state or a short-circuit state may be generated due to the defective soldering process in the same way as in the first embodiment.  
         [0032]    In order to repair the solder ball  3   a  and/or  3   b  in FIG. 5B, the resin film  5   a  and/or  5   b  is first removed by a mechanical or chemical process. Then, the solder ball  3   a  and/or  3   b  can be repaired in the same way as in the first embodiment. Thus, the solder ball  3   a  and/or  3   b  can be repaired without separating and detaching the interposer substrate  2  from the motherboard  4 , which would decrease the manufacturing cost.  
         [0033]    As explained hereinabove, according to the present invention, since defective solder balls can be repaired without separating and detaching an interposer substrate from a motherboard, the manufacturing cost can be decreased. Note that BGA semiconductor devices including such defective solder balls can be reused.