Abstract:
Electrical connection of a measuring socket to an IC package, to measure electrical characteristics of the IC package, is realized by bringing a measuring pin of a measuring arm of the measuring socket into contact with an end surface of a distal end of a lead of the IC package. Accordingly, a problem of solder plated to the lead becoming attached to and deposited on an upper side of a socket pin and shaved off by the distal end of the lead, and thereby producing solder residue, is solved. This problem occurs when electrical connection to an IC package is conventionally realized by bringing the distal end of the lead of the IC package into contact with a distal end of the socket pin.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the invention  
           [0002]    The present invention relates to a semiconductor-package measuring method for testing electrical characteristics of a semiconductor package by setting the semiconductor package individually into a measuring socket in the semiconductor-package inspecting step, to a measuring socket of a semiconductor package, and to a semiconductor package to be tested.  
           [0003]    2. Description of the related art  
           [0004]    Conventionally, the inspecting step of testing an IC package, which has been formed into an individual piece by molding the IC package onto a lead frame with a mold resin and then soldering the package onto the surface of the lead frame and lead-working the package, has been manually executed or automatically executed while the IC package was automatically carried. The inspecting step described below is automatically executed.  
           [0005]    [0005]FIG. 7 is a view showing a conventional IC-package measuring method, and is a schematic sectional view of a measuring device viewed from a side thereof.  
           [0006]    A test tray  2  mounting an IC package  1  is transported by a not-illustrated transporting mechanism and the IC package  1  is set to an inspection position at which a socket  3  is disposed. In this case, the IC package  1  is positioned to a position at which the distal end of a lead  4  of the IC package  1  contacts the distal end of a conductive socket pin  5  of the socket  3 .  
           [0007]    Then, a lead-holding portion  7  made of an insulator and provided for a lead holding mechanism  6  of the measuring device lowers from the upper side to lower the test tray  2  simultaneously with the IC package  1  and bring the distal end of the lead  4  of the IC package  1  into contact with an upper surface of the distal end of the socket pin  5 .  
           [0008]    The lead holding mechanism  6  stops at a position where the mechanism  6  contacts a stopper  8  of a lead holder provided for the socket  3 . Thereby, the lead holding portion  7  stops at a position further down by a certain distance from a position where the portion  7  contacted the lead  4  of the IC package  1 . A stroke of the lead holding mechanism  6  from a position at which the lead holding portion  7  contacts the inserted lead  4  of the IC package  1  to the stopper  8  is referred to as socket pushing distance B.  
           [0009]    In this case, the lead  4  and socket pin  5  move from the position shown by a continuous line to the position shown by an alternate-long-and-short-dash line and the lead  4 , socket pin  5 , a conductive portion of the socket  3 , and a contact  9  are electrically connected with a not-illustrated measuring device, and thereby electrical characteristics are measured.  
           [0010]    [0010]FIGS. 8A and 8B are enlarged views of the portion A in FIG. 7, in which FIG. 8A shows a case when the lead  4  and socket pin  5  are present at the continuous-line position and FIG. 8B shows a case when the same are present at the alternate-long-and-shortdash-line position.  
           [0011]    Solder residue  10  is solder deposited on the socket pin  5  when the lead  4  is set to the socket pin  5  as shown in FIG. 8A, which solder was used for solder-plating the surface of the lead  4  of the IC package  1  in a previous step.  
           [0012]    In the conventional IC-package measuring method described above, however, the deposited solder residue  10  is shaved off at the distal end of the lead  4  as shown in FIG. 8B during the stroke of the socket pushing distance B.  
           [0013]    The shaved-off solder residue  10  attaches to the surface of the lead  4  or between a plurality of the leads  4  to cause a problem that the IC package  1  is mis-measured and the operating rate of the measuring device is lowered.  
         SUMMARY OF THE INVENTION  
         [0014]    To solve the above problem, the present invention measures electrical characteristics by bringing a measuring pin of a measuring arm of a measuring socket into contact with an end surface of a distal end of a lead of a semiconductor package.  
           [0015]    In accordance with the present invention, because electrical characteristics are measured by bringing the measuring pin into contact with an end surface of the distal end of the lead, no solder residue is produced and thus IC packages are not mis-measured and the operating rate of the measuring device is improved. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a view showing a first embodiment of the present invention.  
         [0017]    [0017]FIG. 2 is a view showing a measuring method of the first embodiment.  
         [0018]    [0018]FIG. 3 is a view showing a second embodiment of the present invention.  
         [0019]    [0019]FIG. 4 is an enlarged view of the distal end of a lead.  
         [0020]    [0020]FIG. 5 is a side view of a measuring socket of the second embodiment of the present invention viewed from the direction of the arrow E in FIG. 3.  
         [0021]    [0021]FIGS. 6A and 6B are views showing a third embodiment of the present invention.  
         [0022]    [0022]FIG. 7 is a view showing a conventional IC-package measuring method.  
         [0023]    [0023]FIGS. 8A and 8B are enlarged views of portion A of FIG. 7. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    [0024]FIG. 1 is a view showing the first embodiment of the present invention, and is a schematic sectional view of a principal portion including a measuring socket viewed from the side.  
         [0025]    A seat  13  provided with a lead-receiving portion  12 , for receiving by point contact a bottom of a distal end of a lead of an IC package such as a semiconductor package, is provided at an end of a measuring socket  11  made of synthetic resin.  
         [0026]    A distal end of the lead-receiving portion  12  is formed as a point, and the lead-receiving portions  12  (sockets to be electrically connected with measuring sockets for measurement) corresponds to a number of leads to be tested.  
         [0027]    Moreover, measuring arms  14  corresponding to the number of leads to be measured are linearly arranged near the seat  13  and are rotatably supported by a shaft  15 .  
         [0028]    The measuring arm  14  is formed of a conductive material in a gentle L-shape as a whole, a hole is formed near a central portion of the arm  14 , and the insulator shaft  15  is passed through the hole.  
         [0029]    A convex measuring pin  16  such as a pin having an acuteangular distal end is formed at one end of the measuring arm  14 . When the lead-receiving portion  12  receives a lead, the distal end of the measuring pin  16  is positioned so as to line-contact at a central portion of an end surface of the lead in the thickness direction thereof.  
         [0030]    Moreover, the measuring arm  14  is constantly urged by a spring  17  such that the measuring pin  16  is kept separate from the distal end of the lead.  
         [0031]    A rotational-mechanism portion  19  provided at a lead-holding mechanism  18  of the measuring device contacts another end of the measuring arm  14 . When a distal end of the rotational-mechanism portion  19  presses the other end of the measuring arm  14  downward, the measuring arm  14  rotates against the spring  17  with the shaft  15  serving as a fulcrum.  
         [0032]    A portion of the measuring arm  14  extended toward the other end of the arm  14  from a portion slightly separate from the shaft  15  of the arm  14  is formed to have a certain angle, and a contact such as a POGO contact pin  20  is embedded in the measuring socket  11  and a board  21  under this portion of the measuring arm  14 .  
         [0033]    POGO contacts  20  equal to the number of measuring arms  14  are linearly arranged such that the bottom of each measuring arm  14  contacts and electrically connects with the head of each POGO contact pin  20 .  
         [0034]    The POGO contact pin  20  is connected to a measuring device used to measure an electrical characteristic of the IC package, and it is also possible to apply a contact probe to the pin  20 .  
         [0035]    A lead-holding arm  22  made of an insulating material is set at the lead-holding mechanism  18 . The lead-holding arm  22  is constituted so as to move downward, hold the distal end of the lead of the IC package mounted on the test tray  2  together with the lead-receiving portion  12  of the seat  13 , and further move downward, while holding the lead, to an upper side of a stopper  23  set at the board  21 .  
         [0036]    [0036]FIG. 2 is a view showing a measuring method of the first embodiment, and is a schematic sectional view of a principal portion of the measuring socket and the like to which the IC package is set, viewed from the side.  
         [0037]    The test tray  2  on which the IC package  1  is mounted is transported by a not-illustrated transporting mechanism and the IC package  1  is set to an inspection position at which the measuring socket  11  is disposed. In this case, the distal end of the lead  4  of the IC package  1  is positioned to a position corresponding to the measuring pin  16 .  
         [0038]    Then, the lead-holding mechanism  18  lowers from the upper side, the distal end of the lead  4  is held by the lead-receiving portion  12  of the seat  13  formed at the measuring socket  11  and the lead-holding arm  22 , and the lead-holding mechanism  18  further lowers, while holding the distal end of the lead  4 , to the upper side of the stopper  23 .  
         [0039]    At this time, the distal end of the lead  4  point-contacts the lead-receiving portion  12 .  
         [0040]    When the lead-holding mechanism  18  lowers, the rotational-mechanism portion  19  lowers in the direction of arrow C to press the end of the measuring arm  14  opposite to the end thereof at which the measuring pin  16  is formed.  
         [0041]    Then, the measuring arm  14  rotates in the direction of arrow D against the spring  17 , using the shaft  15  as a fulcrum, and the measuring pin  16  perpendicularly contacts the end surface of the distal end of the lead  4 . The pointed distal end of the measuring pin  16  line-contacts the central portion of the section of the lead  4  in the thickness direction thereof.  
         [0042]    When the measuring arm  14  rotates, the bottom of the measuring arm  14  contacts the POGO contact pin  20 , the lead  4  of the IC package  1  and the POGO contact pint  20  are electrically connected through the measuring pin  16  and measuring arm  14 , and electrical characteristics of the IC package  1  are measured by a measuring device connected with the POGO contact pin  20 .  
         [0043]    At this time, the measuring pin  16  contacts the end surface of the distal end of the lead  4 . However, the lead  4  was cut by individual-piece punching after solder-plating of the lead  4 , and thus no solder remains on the end surface and no solder is transferred (attached) to or deposited on the measuring pin  16 .  
         [0044]    Moreover, because the lead-receiving portion  12  of the synthetic-resin seat  13  receives the distal end of the lead  4  by point contact, no solder is attached to the seat  13 .  
         [0045]    As described above, according to the first embodiment, because electrical characteristics are measured by bringing the measuring pin  16  into contact with the end surface of the distal end of the lead  4 , no solder is attached to or deposited on the measuring pin  16  and no solder residue is produced.  
         [0046]    Therefore, no solder residue attaches to the surface of the lead  4  or between the leads  4 , no IC package  1  is mis-measured, and it is possible to improve the operating rate of a measuring device.  
         [0047]    [0047]FIG. 3 is a view showing the second embodiment of the present invention, and is a schematic sectional view of a principal portion of a measuring socket and the like at which an IC package is set, viewed from the side.  
         [0048]    [0048]FIG. 4 is an enlarged sectional view of a distal end of a lead of an IC package and FIG. 5 is a side view of the second embodiment in FIG. 3, viewed from the direction of arrow E, in which view measuring arms are omitted.  
         [0049]    As shown in FIG. 4, a V-shaped groove  26  is formed at the bottom of the distal end of a lead  25  of an IC package  24 .  
         [0050]    As shown in FIG. 5, concave grooves  29  respectively having a width into which the lead  25  can be inserted and corresponding to the number of the leads  25  are formed in a seat  28  formed at an end of a measuring socket  27 .  
         [0051]    A lead-receiving portion  30  whose cross section is formed into an acute angle is set in the groove  29 . As shown in FIG. 4, the lead-receiving portion  30  engages and line-contacts with the V-shaped groove  26  formed at the bottom of the distal end of the lead  25 .  
         [0052]    As shown in FIG. 5, a distal end  32  of a lead-holding arm  31  of the lead-holding mechanism  18  is formed into a convex shape so as to correspond to the concave shape of the groove  29  of the seat  28  and functions so as to hold the distal end of the lead  25  by the lead-receiving portion  30  and the distal end  32 .  
         [0053]    Other structures are the same as those of the first embodiment, and the measuring method is the same as in the first embodiment except that the distal end of the lead  25  is held by the convex distal end  32  of the lead-holding arm  31  and the lead-receiving portion  30  of the seat  28 , and the V-shaped groove  26  of the lead  25  engages with the lead-receiving portion  30 . Therefore, descriptions of the other structures are omitted.  
         [0054]    According to the second embodiment as described above, in addition to the advantages of the first embodiment, the lead  25  is prevented from bending toward an the IC package side when the measuring pin  16  is pressed and the measuring arm  14  is rotated to bring the pin  16  into contact with an end surface of the lead  25 , because a pressure applied to the distal end of the lead  25  is controlled by the V-shaped groove  26  and lead-receiving portion  30 .  
         [0055]    [0055]FIGS. 6A and 6B are views showing the third embodiment of the present invention, and FIG. 6A is a top view of the IC package and FIG. 6B is an enlarged top view of a portion F in FIG. 6A at which portions of a seat and a measuring pin are added.  
         [0056]    A distal end of a lead  34  of an IC package  33  is cut when the distal end of the lead is worked after solder-plating. An end surface of the distal end is formed into a concave shape such as the V-shape shown in FIG. 6B.  
         [0057]    Moreover, a measuring pin  35  of the measuring arm is formed into a convex shape such as a reversed V-shape so as to engage an end surface shape of the distal end of the lead  34 .  
         [0058]    Other structures are the same as those of the second embodiment.  
         [0059]    When the distal end of the lead  34  of the IC package  33  is set at a lead-receiving portion  30  of the seat  28 , the same as in the second embodiment, a reversed V-shaped portion of the measuring pin  35  contacts a V-shaped portion formed in the end surface of the distal end of the lead  34  and is pressed to be electrically connected, and electrical characteristics of the IC package  33  are measured.  
         [0060]    Thus, by forming the end surface of the distal end of the lead  34  into a concave shape and the distal end of the measuring pin  35  into a reversed V-shape, a position of the lead  34  is corrected by the distal end of the measuring pin  35  even if the IC package  33  is slightly shifted from a predetermined inspecting position while it is transported.  
         [0061]    Moreover, because no solder is present on the end surface of the distal end of the lead  34 , no solder residue is produced.  
         [0062]    According to the third embodiment as described above, in addition to the effect of the second embodiment, because the shape of the end surface of the distal end of the lead  34  and that of the distal end of the measuring pin  35  are formed so that they are easily engaged with each other, a position of the lead  34  is corrected by the distal end of the measuring pin  35  and the lead  34  thereby securely contacts the measuring pin  35  and proper measurement can be performed.