Abstract:
A connector for connecting with an external terminal on an electronic component includes a spiral contact which is wound a plurality of turns. The spiral contact has a single projection that projects outwardly toward an outer circumference of the turns. When the spiral contact is in contact with the external terminal, the projection of the spiral contact comes into contact with the external terminal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a divisional of U.S. patent application Ser. No. 10/889,767 filed on Jul. 12, 2004, in the name of Shin Yoshida, and entitled “CONNECTOR,” which is incorporated herein by reference in its entirety and for all purposes. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a connector included in a testing socket having, for example, an electronic component such as a semiconductor. More specifically, the invention relates to a connector that provides a stable electrical connection between a connection terminal on the electronic component and a connection terminal on the testing socket.  
         [0004]     2. Description of the Related Art  
         [0005]     The semiconductor testing apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2002-175859 provides an interim electrical connection between a semiconductor and an external circuit board. A grid or matrix consisting of a plurality of spherical contacts is disposed on the back side of the semiconductor. A plurality of depressions is formed on an insulating substrate opposing the back side of the semiconductor. In these depressions, spiral contacts are disposed such that they oppose the spherical contacts.  
         [0006]     When the back side of the semiconductor is pressed towards the insulating substrate, the spiral contact wraps around and comes in contact with the outer surface of the spherical contact. In this way, the spherical contacts and the spiral contacts are reliably connected electrically.  
       SUMMARY OF THE INVENTION  
       [0007]     For the above-mentioned semiconductor testing apparatus, the characteristics of the semiconductor have to be measured with high accuracy. In order to do so, spiral contacts on the semiconductor testing apparatus and the spherical contacts on the semiconductor must be stably connected.  
         [0008]     There is, however, a case in which, for example, the spiral contacts undergo plastic deformation or different pressure is applied to different areas due to restrictions such as the shape of the semiconductor. In such a case, the location of the electrical contact point between each pair of spherical contact and spiral contact differs in that, for example, a contact point is formed near the root of the spiral contact and another contact point is formed near the tip of the spiral contact. This is a problem because maintaining a stable electrical connection between the spiral contacts and the spherical contacts becomes difficult.  
         [0009]     It is often believed that a stable electrical connection can be obtained by increasing the pressure applied to the contact points between the spiral contacts and the spherical contacts by increasing the pressure applied to the semiconductor.  
         [0010]     However, increasing the pressure applied to the semiconductor is not necessarily the best solution because there is a limit to the amount of pressure that can be applied to the semiconductor and because it is preferable to apply less pressure to prevent damaging the semiconductor. Another reason is that the amount of pressure applied to each contact point decreases as the number of contact points increase and, thus, sufficient pressure may not be applied to each contact point.  
         [0011]     An object of the present invention is to solve the above-mentioned problems and to provide a connector that is capable of forming a stable electrical connection between the spiral contacts on the testing apparatus and the spherical contacts on the electronic component, such as a semiconductor, while less pressure is applied to the contact points. In other words, while the spring pressure of the entire spiral contact is maintained constant, the contact area is minimized and the contact pressure per unit area is increased so that the film on the surface of the contact point can be easily removed.  
         [0012]     A connector for connecting with an external terminal on an electronic component includes a spiral contact which is wound a plurality of turns. The spiral contact has a single projection that projects outwardly toward an outer circumference of the turns. When the spiral contact is in contact with the external terminal, the projection of the spiral contact comes into contact with the external terminal.  
         [0013]     In one example embodiment of the invention, the projection is formed in a vicinity of a tip of the spiral contact. In another example embodiment of the invention, an end of the projection constitutes an acute angle.  
         [0014]     In the connector according to the present invention, a protrusion that is a discontinuous contact point formed on the spiral contact on the connector comes into contact with parts of the spherical contact on the semiconductor. In this way, an electrical connection between the two contacts can be maintained. In particular, since the spiral contact and the spherical contact come into contact at the protrusion, the electrical connection between these contacts can be stabilized. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a perspective view of a testing socket used for testing the operation of an electronic component.  
         [0016]      FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1  of the testing socket including the electronic component.  
         [0017]      FIG. 3  is a plan view of a spiral contact according to a first embodiment of the present invention.  
         [0018]      FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 3  in which the area between a spiral contact and a spherical contact is partially enlarged.  FIG. 4A  illustrates the state before the contacts come in contact, and  FIG. 4B  illustrates the state after the contacts come in contact.  
         [0019]      FIG. 5  is a plan view of a spiral contact according to a second embodiment of the present invention.  
         [0020]      FIG. 6  is a cross-sectional view taken along line VI-VI of  FIG. 5  illustrating a state in which a spiral contact and a spherical contact are in contact.  
         [0021]      FIG. 7  is a plan view of a spiral contact according to a third embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]      FIG. 1  is a perspective view of a testing socket for testing the operation of an electronic component.  FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1  and illustrates the testing socket including the electronic component.  
         [0023]     As illustrated in  FIG. 1 , a testing socket  10  includes a base  11  and a cover  12  rotatably supported at one of the edges of the base  11  by a hinge  13 . The base  11  and the cover  12  are composed of a material such as an insulating resin. On the central part of the base  11 , a loading region  11 A that is a depression towards the Z 2  direction in the drawing is formed. An electronic component  1  such as a semiconductor can be disposed in the loading region  11 A. At the other edge of the base  11 , a lock-receiving member  14  is formed. On the cover  12 , a locking member  15  that engages with the lock-receiving member  14  is formed.  
         [0024]     As illustrated in  FIG. 2 , the testing socket  10  is for conducting a test on the electronic component  1  including a matrix (or grid) of a plurality of spherical contacts (external terminals)  1   a  disposed on the lower surface.  
         [0025]     As illustrated in  FIG. 2 , the loading region  11 A has a predetermined diameter. A plurality of depressions (through-holes)  11   a  penetrating from the front surface of the loading region  11 A to the back surface of the base  11  is formed to correspond to each of the spherical contacts  1   a  of the electronic component  1 . The upper surface of the depressions  11   a  (the front surface of the loading region  11 A) includes spiral contacts (connection terminals)  20 .  
         [0026]     On the inner wall of the depressions  11   a , plated conductive regions  17  are formed (refer to  FIG. 4B ). The upper edge of the plated conductive regions  17  and a base  21  of the spiral contacts  20  are connected by, for example, a conductive adhesive. The lower edge of the lower opening of the depressions  11   a  is covered with a connection terminal  18  connected to the conductive regions  17 .  
         [0027]     As illustrated in  FIG. 2 , at the lower area of the base  11 , a printed board  30  including a plurality of electrical lines and other circuit components is disposed. The base  11  is fixed on the printed board  30 . On the front surface of the printed board  30 , an opposing electrode  31  opposing the connection terminal  18  on the bottom surface of the base  11  is disposed. When each connection terminal  18  comes into contact with the corresponding opposing electrode  31 , the electronic component  1  and the printed board  30  are electrically connected via the testing socket  10 .  
         [0028]     On the center of the inner surface of the cover  12  of the testing socket  10 , a pressing member  12   a  projecting downwards (in the drawing) to press down the electronic component  1  is formed so that it opposes the loading region  11 A. In the area opposite the hinge  13 , the locking member  15  is formed.  
         [0029]     A biasing member (not depicted in the drawings) including a coil spring for biasing the pressing member  12   a  in a direction away from the inner surface of the cover  12  is disposed between the cover  12  and the pressing member  12   a . Thus, when the electronic component  1  is disposed in the depressions  11   a  and the cover  12  is closed by engaging the locking member  15  with the lock-receiving member  14 , the electronic component  1  is resiliently pressed in the direction towards the front surface of the loading region  11 A (direction Z 2 ).  
         [0030]     The size of the loading region  11 A of the base  11  is substantially the same as the outline of the electronic component  1 . Thus, when the electronic component  1  is disposed in the loading region  11 A and the cover  12  is locked, the spherical contacts  1   a  on the electronic component  1  and the corresponding spiral contacts  20  on the testing socket  10  are accurately aligned.  
       First Embodiment  
       [0031]      FIG. 3  is a plan view of spiral contacts according to a first embodiment of the present invention.  FIG. 4  is a cross sectional view taken along line IV-IV of  FIG. 3  in which the area between a spiral contact and a spherical contact is partially enlarged.  FIG. 4A  illustrates the state before the contacts come in contact, and  FIG. 4B  illustrates the state after the contacts come into contact.  
         [0032]     A spiral contact  20 A illustrated in  FIG. 3  is formed flush with a plane. The periphery of the spiral contact  20 A is surrounded by a square base  21 . The base  21  is fixed to the edge of the upper opening of a depression  11   a.    
         [0033]     As illustrated in  FIG. 3 , a root  22  of the spiral contact  20 A is located at the base  21 , and a tip  23  extending in a spiral from the root  22  is located at the center of the depression  11   a.    
         [0034]     For the spiral contact  20 A according to the first embodiment illustrated in  FIG. 3 , the width of the root  22  is WO and the width of the tip  23  is W 1 , which is slightly smaller than WO (WO&gt;W 1 ). The width of the spiral contact  20 A becomes continuously smaller at a predetermined rate from the root  22  having a width of WO to the tip  23  having a width of W 1 .  
         [0035]     If the entire length of the spiral contact  20 A, from the root  22  to the tip  23 , is L and the length from the root  22  to a predetermined position closer to the tip  23  is X (where  0 &lt;X&lt;L), the width of the spiral contact  20 A at a predetermined position X can be indicated by Formula  1  below.  
             W   =             W   ⁢           ⁢   1     -     W   ⁢           ⁢   0       L     ·   X     +     W   ⁢           ⁢   0               [     Formula   ⁢           ⁢   1     ]             
 
         [0036]     The spiral contact  20 A according to the first embodiment, however, includes a discontinuous contact region  24  having a width that differs from the width determined by Formula  1  and being formed at a predetermined position between the root  22  and the tip  23 . In other words, the discontinuous contact region  24  is a protrusion protruding from the side of the spiral contact  20 A towards the center and which is flush with the spiral contact  20 A (the discontinuous contact region  24  is a protrusion on the inner circumference).  
         [0037]     The width W of the spiral contact  20 A according to the present invention is not limited to the above and may be constant for the entire length of the spiral contact  20 A (W 0 =W 1 ). Moreover, if the resilient strength in the Z direction can be maintained, the width of the spiral contact may be W 0 &lt;W 1 .  
         [0038]     As illustrated in  FIG. 4B , when the locking member  15  of the cover  12  is engaged with the lock-receiving member  14  of the base  11 , the electronic component  1  is pushed downwards (in the drawing) by the pressing member  12   a . Therefore, each of the spherical contacts  1   a  pushes each of the corresponding spiral contacts  20 A towards the inside of the depressions  11   a  (downwards in the drawing). Simultaneously, the outline of the spiral contact  20 A is deformed so that it expands from the tip  23  towards the root  22  (from the center of the spiral to the periphery of the spiral). In this way, the spiral contacts  20 A wrap around the outer surface of the spherical contacts  1   a  to electrically connect the spherical contacts  1   a  and the spiral contacts  20 .  
         [0039]     Hence, the spherical contacts  1   a  and the corresponding spiral contacts  20  constitute connectors for electrically connecting the electronic component  1  and an electrical circuit on the printed board  30 . At this time, the angular portion at the tip of the discontinuous contact region  24  comes into contact with the surface of the corresponding spherical contact  1   a  first since the discontinuous contact region  24  of the spiral contact  20 A protrudes in the width direction of the spiral contact  20 A,. In other words, the spiral contact  20 A and the corresponding spherical contact  1   a  can always be electrically connected via a contact point P on the angular portion at the tip of the discontinuous contact region  24  and the surface of the corresponding spherical contact  1   a . Thus, the distance from the root  22  of the spiral contact  20 A and the contact point P becomes constant. In this way, a change in the electrical characteristics such as a contact resistance that easily changes every time the spiral contact  20 A and the spherical contact  1   a  come into contact can be suppressed, and the electrical connection between the spiral contact  20 A and the spherical contact  1   a  can be stabilized.  
         [0040]     The preferable size of the contact point P for this case is 100 μm or less in diameter.  
         [0041]     The spiral contact  20 A illustrated in  FIG. 3  includes a narrow region S that has a smaller width than the regular width of the spiral contact  20 A (i.e., the narrow region S has a width smaller than the width W calculated from Formula  1  or the predetermined constant width). A narrow region S is formed in an area opposing the discontinuous contact region  24  in respect to the central axis  0  and one turn outwards from the discontinuous contact region  24 .  
         [0042]     If such a narrow region S is formed, as illustrated in  FIG. 4B , when the spherical contacts  1   a  come in contact with the surface of the spiral contact  20 A, the inner circumference of the narrow region S is tilted and pressed downwards in the Z 2  direction more than the outer periphery. At this time, a torsional moment M is applied to the narrow region S of the spiral contact  20 A in a clockwise direction, as illustrated in the drawing. Similarly, as illustrated in the drawing, a counter-clockwise torsional moment M is applied to the area opposing the narrow region S in respect to the central axis  0 . For this reason, the discontinuous contact region  24  of the spiral contact  20 A is also tilted and the inner circumference is pressed downwards.  
         [0043]     Accordingly, as illustrated in  FIG. 4B , the tip of the angular portion of the discontinuous contact region  24  easily comes into contact with the surface of the spherical contact  1   a , and the contact point P can be formed between each spiral contact  20 A and the tip of the angular portion of the corresponding spherical contact  1   a . Therefore, when the pressure applied to the contact points between the spiral contacts  20 A and the spherical contacts  1   a  is small, or, in other words, when a plurality of spherical contact regions of the electronic component  1  and a plurality of spiral contacts  20 A of the testing socket  10  are connected, each of the spherical contacts  1   a  and the corresponding spiral contacts  20 A come into contact via each contact point P. In this way, the electrical connection between the spherical contacts  1   a  and the corresponding spiral contacts  20 A becomes stable.  
       Second Embodiment  
       [0044]      FIG. 5  is a plan view of a spiral contact according to a second embodiment of the present invention.  FIG. 6  is a cross-sectional view taken along line VI-VI of  FIG. 5  and illustrates the connection between a spiral contact and a spherical contact.  
         [0045]     A spiral contact  20 B according to the second embodiment illustrated in  FIG. 5  differs from the spiral contact  20 A according to the first embodiment in that the discontinuous contact region  24  is a protrusion protruding towards the outer circumference of the spiral contact  20 B instead of protruding towards the inner circumference (the discontinuous contact region  24  is a protrusion on the outer circumference).  
         [0046]     As illustrated in  FIG. 6 , similar to that described above, for the spiral contact  20 B according to the second embodiment, when the electronic component  1  is pressed towards the Z 2  direction, the tip of the angular portion of the discontinuous contact region  24  of the spiral contact  20 B comes into contact with the surface of a spherical contact  1   a  to form a contact point P. The spherical contact  1   a  and the spiral contact  20 B are electrically connected via the contact point P. Thus, similar to the first embodiment, the electrical connection between the spiral contact  20 B and the spherical contact  1   a  is stabilized.  
         [0047]     The spiral contact  20 B according to the second embodiment is particularly effective when a large torsional moment is applied to the spiral contact  20 B because the diameter of the spherical contact  1   a  is small or when the pressure applied to the contact point in the Z 2  direction is large.  
       Third Embodiment  
       [0048]      FIG. 7  is a plan view of a spiral contact according to a third embodiment of the present invention.  
         [0049]     A spiral contact  20 C according to the third embodiment differs from the spiral contacts  20 A and  20 B according to the first and the second embodiments, respectively, in that the discontinuous contact region  24  is not a protrusion and, instead, is a notch in the spiral contact  20 C. Even if the discontinuous contact region  24  is a notch, the discontinuous contact region  24  can partially come into contact with the surface of a spherical contact  1   a  and form a contact point P similar to that described above.  
         [0050]     Since the discontinuous contact region  24  according to the first and second embodiments is a protrusion and a two-dimensional structure formed on a plane, it can be formed easily by common methods such as photolithography.  
         [0051]     In the above embodiments, the discontinuous contact region  24  is formed on one location on the spiral contact  20 . The discontinuous contact region  24  according to the present invention, however, is not limited to one location and may be formed in a plurality of locations. When a plurality of discontinuous contact regions  24  are formed, a plurality of contact points P are also formed. Thus, the electrical connection between the spiral contacts  20  and the spherical contacts  1   a  can be stabilized even more.  
         [0052]     In the above embodiments, the contact for the testing socket was a spherical contact (ball grid array (BGA)). The present invention, however, is not limited to this and, for example, a land grid array (LGA), ellipsoid contact, a cone contact, or a polygonal pyramid contact may be used.