Abstract:
A connector includes a movable conductive element and an elastic body. The connector electrically conducts between opposed external electrodes disposed vertically. The movable conductive element has a pair of rigid contact. And the elastic body deforms elastically to receive the load caused by the movement of the movable conductive element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2009-206273, filed on Sep. 7, 2009, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to a technology for a connector and an interposer using the connector. 
     BACKGROUND 
     Conventionally, when a semiconductor integrated circuit (IC) package is mounted on a circuit board, lead wires projecting from the side surface of the IC package are inserted into through-holes with lands of a circuit pattern on the circuit board. And the lead wires are electrically connected to the lands with solder. On the other hand, in recent years, the number of input-output terminals of the IC package is increasing with improvement of the integration density of the IC. Furthermore since operating frequency of the IC rises, there is a demand for improving the high-frequency characteristic of the circuit board. Therefore demands for high density mounting on the circuit board and short distance connection in the circuit board and narrow pitch mounting on the circuit board are increasing. 
     For example, techniques for providing the input-output terminals in a reticular pattern formed on the back side of the IC package such as BGA (Ball Grid Array) and LGA (Land Grid Array) and for mounting the IC package on the surface of the circuit board so as to dispose the input-output terminals efficiently under these demands are proposed. The surface mount technology that uses an interposer as an interconnecting board between the IC package and the circuit board is proposed. The interposer includes an insulation material sheet and a conductor (for example, connector). The insulation material sheet has through-holes corresponding to input-output terminals formed in a grid-array pattern on the IC package. And the conductors are inserted into these through-holes to conduct electrically in vertical direction of the insulation material sheet. Terminal patterns arranged in a grid-array pattern that is similar to that of the IC package are formed on the circuit board. It is illustrated using  FIG. 1  to mount the IC package on the circuit board using the interposer. 
       FIGS. 1A to 1C  illustrate a conventional interposer.  FIG. 1A  illustrates that an interposer  2  is disposed between a circuit board  3  and an IC package  1 . Moreover,  FIG. 1B  illustrates a side view of  FIG. 1A , and especially a cross-sectional view of the interposer  2 . Input-output terminals  4  (electrodes) are provided in a grid-array pattern formed on the back side of the IC package  1 . And for mounting the IC package  1  on the circuit board  3 , each of terminal patterns  6  (electrodes) is formed at position corresponding to each of the input-output terminals  4 . 
     The interposer  2  is disposed between the IC package  1  and the circuit board  3 , and connects the input-output terminals  4  on the back side of the IC package  1  to the terminal patterns  6  on the circuit board  3 . The interposer  2  has a plurality of through-holes  9 , which are formed into the insulation material sheet (hereinafter called an interposer substrate)  8 . Each of the through-holes  9  corresponds to each of the input-output terminals  4  in the grid-array pattern formed on the IC package  1 . A connector  5  is inserted into the through-hole  9 . Each of the connectors  5  is the same length, and the connector  5  is made of the conductive material that electrically conducts between the front side and the back side of the interposer substrate  8 . 
     The interposer  2  is generally disposed inside a socket  7  illustrated in  FIG. 1C , and the socket  7  is mounted on the circuit board  3  by soldering. When the socket  7  is used, the IC package  1  is easy to mount and demount on the circuit board  3 . 
     In the interposer  2  as mentioned above, the structure of the connector  5  that is made of the conductor which conducts electricity between the front side and the back side of the interposer substrate  8  is important. The connector  5  is placed and compressed between the input-output terminal  4  on the back side of the IC package  1  and the terminal patterns  6  on the circuit board  3 . Therefore the connector  5  has elasticity to conduct electricity between the IC package  1  and the circuit board  3  while being compressed under pressure from both the IC package  1  and the circuit board  3 . 
     As a structure to provide elasticity to the connector  5 , Japanese Laid-open Patent Publication No. 2001-176580 (hereinafter called “patent document 1”) discloses the connector that includes a flexible conductive element wound around the compressible insulating core and a compressible elastic outer shell the surrounding the conducting element. The patent document 1 also discloses that the outer shell is an elastic body such as rubber, and that the outer shell surrounding the core is surrounded by an insulating layer made of a conductive wire mesh or a continuous metallic layer. 
     However, as a structure to provide elasticity to the connector  5 , the patent document 1 discloses the structure that builds a zigzag wire, a pleat wire or a coiled wire into the main body of the elastic body, and discloses the structure that builds a metallic spring into the main body of the elastic body. However, there is a problem that the structure disclosed in the patent document 1 physically has the limit of downsizing. Moreover, there are problems that the structure disclosed in the patent document 1 is complex and causes high cost. 
       FIGS. 2A to 2D  illustrate a conventional connector. As the solution of the problems described above, the connector  50  that has an elastic connection body  52  illustrated in  FIG. 2A  is proposed. The connector  50  has the elastic connection body  52  that includes a U-shape conductive spring  53 , and the connector  50  is fitted in a through-hole  9  of the interposer substrate  8  as illustrated in  FIG. 2B . 
     Both ends of the spring  53  of the elastic connection body  52  are contact parts  54  and  55 . As shown in  FIG. 2C , when an interposer  80  is disposed at a predetermined position on the circuit board  3  and the IC package  1  is mounted on the interposer, the contact part  54  contacts the input-output terminal  4  of the IC package  1  and the contact part  55  contacts the terminal pattern  6  of the circuit board  3 . Consequently, the pressure received from the IC package  1  and the circuit board  3  is absorbed as the spring  53  is bent. 
       FIG. 2D  illustrates an interposer  70  including a connector  60  with a similar structure to the connector  50  described in  FIGS. 2A to 2C , and it is described in U.S. Pat. No. 4,969,826 (hereinafter called “patent document 2”). The interposer  70  includes an interposer substrate  68  having through-holes  69  and the connector  60  provided in the through-holes  69 . A contact  65  is provided in a housing  64  of the connector  60 . The contact  65  includes two contact parts  61  and  62  and a spring  63  that connects between the contact part  61  and the contact part  62 . The contact parts  61  and  62  protrude from the top surface and the bottom surface of the interposer substrate  68  respectively. The contact part  61  contacts with the input-output terminal  4  of the IC package  1  and the contact part  62  contacts with the terminal pattern  6  of the circuit board  3  as well as the structure of the connector  50  described in  FIGS. 2A to 2C . 
     However, as illustrated  FIGS. 2A to 2C , the interposer  2  in which the U-shape conductive spring  53  is built has some problems. There are problems that a downsizing of the interposer  2  is limited to secure a prescribed deformation amount of a metallic spring, a design of the interposer  2  is difficult, and an electric resistance of the interposer  2  is large because a current pathway is long.  FIG. 7A  illustrates relation between deformation amount of the connector and contact pressure of the connector. In  FIG. 7A , P in y-axis indicates contact pressure of the connector, A in y-axis indicates a range of the contact pressure, D in x-axis indicates deformation amount of the connector and B indicates a range of the deformation amount. As disclosed in the patent document 2, there is a problem that the range of the contact pressure corresponding to the range of the deformation amount in the contact part is large, that is, the variation of the contact pressure is large, as illustrated in  FIG. 7A . 
     SUMMARY 
     According to an aspect of the invention, a connector includes a movable conductive element and an elastic body. The connector electrically conducts between opposed external electrodes disposed vertically. The movable conductive element has a pair of rigid contact. And the elastic body deforms elastically to receive the load caused by the movement of the movable conductive element. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A to 1C  illustrate a conventional interposer. 
         FIGS. 2A to 2D  illustrate a conventional connector. 
         FIGS. 3A to 3E  illustrate a connector according to a first embodiment. 
         FIGS. 4A to 4B  illustrate a connector according to a second embodiment. 
         FIGS. 5A to 5F  illustrate a connector according to a variation example of the second embodiment. 
         FIGS. 6A to 6C  illustrate a connector according to a third embodiment. 
         FIGS. 7A to 7B  illustrate relation between deformation amount of the connector and contact pressure of the connector. 
         FIGS. 8A to 8D  illustrates a connector according to a fourth embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereafter, a connector and an interposer including the plurality of the connectors according to embodiments are described in detail with reference to the accompanying drawings. 
       FIGS. 3A to 3E  illustrate a connector according to a first embodiment. As a housing unit, the connector  10  includes a base unit  11 , two frames  16  that extend from both ends of the base unit  11  and a positioning unit  17  that is provided with both ends of the two frames  16  as illustrated in  FIG. 3A . In this embodiment, the two frames  16  are perpendicular to the base unit  11 , and the positioning unit  17  is perpendicular to the two frames  16 . Therefore, the positioning unit  17  is parallel to the base unit  11  in this embodiment. 
     A plate-like spring body  12  is extended from the base unit  11  inside the space enclosed by the base unit  11 , the two frames  16  and the positioning unit  17 . And, a holding unit  13  is disposed at the end of the spring body  12 . An enough space remains between the holding unit  13  and the positioning unit  17 . The holding unit  13  is made of conductor. The base unit  11 , the spring body  12 , and the holding unit  13  serve as an elastic body that receives the load caused by the movement of contacts  14  and  15  described below. The contacts  14  and  15  are an example of a movable conductive element described in claims. 
     In addition, nearly L-shaped two contacts  14  and  15  are fitted between the base unit  11  and the holding unit  13 . The contacts  14  and  15  are made of the conductor. There are a long axis  14 D and a short axis  14 E in the contact  14 . The end of the long axis  14 D is an action part  14 A. There is a sliding part  14 B in the intersection part between the long axis  14 D and the short axis  14 E. The end of the short axis  14 E is a contact part  14 C. Similarly, there are a long axis  15 D and a short axis  15 E in a contact  15 . The end of the long axis  15 D is an action part  15 A. There is a sliding part  15 B in the intersection part between the long axis  15 D and the short axis  15 E. The end of the short axis  15 E is a contact part  15 C. The action parts  14 A and  15 A are held by the holding unit  13 . The sliding parts  14 B and  15 B come into contact with the inner surface of the base unit  11 . The contact  14  and  15  are fitted between the base unit  11  and the holding unit  13  so that the contact parts  14 C and  15 C protrude outside the frame  16 . 
     As illustrated in  FIG. 3D , a recess  18  may be provided to receive the action part  14 A of the contact  14  and the action part  15 A of the contact  15  on the inner surface of the holding unit  13 , so that the contacts  14  and  15  fitted between the base unit  11  and the holding unit  13  are prevented from being released.  FIG. 3E  illustrates that the contacts  14  and  15  are fitted between the base unit  11  and the holding unit  13  with a recess  18 . 
     The connector  10  that the contacts  14  and  15  are fitted between the base unit  11  and the holding unit  13  is inserted in a rectangular through-hole  9  formed in the interposer substrate  8 . The interposer substrate  8  is made of a dielectric material. Distance between the outer surface of the base unit  11  and the outer surface of the positioning unit  17  is equal to the length of the long side of the rectangular through-hole  9 . Each of width of the base unit  11  and width of the positioning unit  17  is equal to the short side of the rectangular through-hole  9 . The ratio between the length of the long side of the rectangular through-hole  9  and the length of the short side of the rectangular through-hole  9  is about 1.4:1.  FIG. 3B  illustrates that the connector  10  is inserted in the rectangular through-hole  9  that is formed in the interposer substrate  8 . That is, the interposer  10 P of the first embodiment is that the connector  10  of the first embodiment is inserted in the interposer substrate  8  instead of the connector  5  illustrated in  FIG. 1A . 
       FIG. 3C  illustrates that the IC package  1  is mounted on the front side of the interposer  10 P illustrated in  FIG. 3B  and the circuit board  3  is mounted on the back side of the interposer  10 P. When the contact part  14 C of the contact  14  of the interposer  10 P is pressed by an input-output terminal  4  of the IC package  1  and the contact part  15 C of the contact  15  of the interposer  10 P is pressed by a terminal pattern  6  of the circuit board  3 , the contact parts  14 C and  15 C are points of force, the sliding part  14 B and  15 B are fulcrums, and the action parts  14 A and  15 A are points of action. That is, when suppress strength is added to the contact parts  14 C and  15 C (the points of force), the sliding parts  14 B and  15 B (the fulcrums) slide on the inner surface of the base unit  11  and the action parts  14 A and  15 A (the points of the action) pushes the holding unit  13 . As a result, the spring body  12  is deformed, and the holding unit  13  moves by deforming 
     The contacts  14  and  15  conduct by contact with each other or conduct through the holding unit  13  which is made of conductor. Therefore, the length of path for an electric signal between the contact parts  14 C and  15 C is equal to the length that the length of the contact  14  is added to the length of the contact  15 . The length of the path for the electric signal is shorter than the length of the path for the electric signal in the elastic connection body  52  described in  FIG. 2 . As the contacts  14  and  15  are made of rigid body, each length of the contacts  14  and  15  is not changed by movement of the contacts  14  and  15 . That is, the length of the path for the electric signal between the contact parts  14 C and  15 C before the IC package  1  is mounted as illustrated in  FIG. 3B  is the same as the length of the path for the electric signal between the contact parts  14 C and  15 C after the IC package is mounted as illustrated in  FIG. 3C . 
     Next,  FIGS. 4A to 4B  illustrate a connector according to a second embodiment. The points that the connector  20  of the second embodiment is different from the connector  10  of the first embodiment are that the connector  20  has without the frame  16  and without the positioning unit  17  as illustrated in  FIG. 4A . As the other components are the same as those of the connector  10 , and description thereof is omitted. When the connector  20  in the second embodiment is inserted into the rectangular through-hole  9  that is formed in the interposer substrate  8 , the outer surface of the base unit  11  is bonded on the inner surface of the rectangular through-hole  9 . Moreover, as illustrated in  FIG. 4B , when grooves  9 A in which the base unit  11  is fitted are formed in the rectangular through-hole  9  of the interposer substrate  8 , the connector  20  may be fitted in the interposer substrate  8  without bonding. 
       FIGS. 5A to 5F  illustrate a connector according to a variation example of the second embodiment.  FIG. 5A  illustrates that the connector  20  of the second embodiment illustrated in  FIG. 4C  is inserted into the through-hole  9  formed in the interposer substrate  8 . Moreover,  FIG. 5B  illustrates that the contact part  14 C of the contact  14  of the connector  20  and the contact part  15 C of the contact  15  of the connector  20  are pushed by two electrodes. When the action parts  14 A and  15 A push the holding unit  13  by movement of the contacts  14  and  15 , the spring body  12  is bent and thereby the holding unit  13  moves. As the contacts  14  and  15  are rigid bodies, the contacts  14  and  15  are not deformed. 
       FIG. 5C  illustrates an interposer using a connector  20 A of the first variation of the connector  20  illustrated in  FIG. 5A . In this first variation, the holding unit  13  is angularly disposed to the spring body  12 . The other components are the same as those of the connector  20 .  FIG. 5D  illustrates that the connector  20 A are compressed by the two electrodes. And when the IC package  1  is mounted on the circuit board  3 , as the holding unit  13  becomes parallel to the base unit  11 , the contacts  14  and  15  are stably held to the holding unit  13 . 
       FIG. 5E  illustrates a connector  20 B of the second variation of the connector  20  illustrated in  FIG. 5A . In this second variation, the spring body  12  is made of an accordion spring  12 B. The other components are the same as those of the connector  20 . In the second variation,  FIG. 5F  illustrates that the connector  20 B is compressed by the two electrodes, when the IC package  1  mounted on the circuit board  3 . As a result, the holding unit  13  becomes parallel to the base unit  11  as the accordion spring  12 B expands. Therefore, in the second variation, the contacts  14  and  15  are more firmly held by the holding unit  13 . The shape of the spring body  12  is not limited to the accordion type. 
     Next,  FIGS. 6A to 6C  illustrate a connector according to a third embodiment. The points that a connector  30  of the third embodiment are different from the connector  20  of the second embodiment are a structure of the holding unit  13  and the shape of the action part  32  of the contact  14  and the shape of the action part  33  of the contact  15  engaging with the holding unit  13  as illustrated in  FIG. 6A . The other components are the same as those of the connector  20  of the second embodiment, and description thereof is omitted. In the connector  30  of the third embodiment, a hemisphere recess  31  is formed into the inner surface of the holding unit  13 . And the action part  32  of the contact  34  and the action part  33  of the contact  35  are spherically formed. Reference marks  34 B and  35 B represent sliding parts. Reference marks  34 C and  35  C represent contact parts. The contacts  34  and  35  are fitted between the hemisphere recess  31  of the base unit  11  and the holding unit  13  as well as the connector  10  of the first embodiment and the connector  20  of the second embodiment. 
       FIG. 6B  illustrates a plan view that the connector  30  illustrated in  FIG. 6A  is assembled and is fitted into the through-hole  9  of the interposer substrate  8 . The action part  32  of the contact  34  and the action part  33  of the contact  35  are fitted in the hemisphere recess  31  that is formed in the inner surface of the holding unit  13 . When the terminal pattern  6  (electrode) of the circuit board  3  is connected with the top of the connector  30  (the contact part  34 C) and the input-output terminal  4  (electrode) of the IC package  1  is connected with the bottom (the contact part  35 C) of the connector  30 , the contact part  34 C of the contact  34  of the connector  30  and the contact part  35 C of the contact  35  of the connector  30  are pushed by the two electrodes and move as illustrated in  FIG. 6C . 
       FIG. 6C  illustrates that the spring body  12  curves and the holding unit  13  moves since the action parts  32  and  33  push the holding unit  13  by the movement of the contacts  34  and  35 . However, in the third embodiment, as the holding unit  13  has the hemisphere recess  31 , the action part  32  of the contact  34  and the action part  33  of the contact  35  are more firmly held and held in the hemisphere recess  31 . As a result, the action part  32  of the contact  34  and the action part  33  of the contact  35  are not easily released from the hemisphere recess  31 . 
     A recess may be provided to receive the sliding part  14 B of the contact  14 , the sliding part  15 B of the contact  15 , the sliding part  34 B of the contact  34  and the sliding part  35 B of the contact  35  on the inner surface of the base unit  11 , so that the sliding part  14 B of the contact  14 , the sliding part  15 B of the contact  15 , the sliding part  34 B of the contact  34  and the sliding part  35 B of the contact  35  do not release from the base unit  11  when they slide on the base unit  11 . 
     Next,  FIGS. 7A and 7B  illustrate relation between deformation amount of the connector and contact pressure of the connector. In  FIGS. 7A and 7B , P in y-axis indicates the contact pressure of the connector, A in y-axis indicates a range of the contact pressure, D in x-axis indicates deformation amount of the connector and B indicates a range of the deformation amount.  FIG. 7B  illustrates linear change of spring load that a moving member receives from an elastic member. The range of the contact pressure illustrated in  FIG. 7B  in the connector of the embodiments is smaller than the range of the contact pressure illustrated in  FIG. 7A  in a conventional connector corresponding to the same range of the deformation amount. That is, the variation of the contact pressure in the connector of the embodiments is small. Therefore, in the interposer including the connector according to the embodiments, the interposer has the advantage of stability and high reliability even if the interposer connects a plurality of pins. Therefore the interposer using the connector of the embodiments improves high reliability and signal quality of a component that large and a high-speed IC package is stacked and mounted on the circuit board via the interposer. As a result, a higher-speed apparatus with higher density mounting may be developed. 
       FIGS. 8A to 8D  illustrates a connector according to a fourth embodiment. The points that a connector  40  of the firth embodiment is different from the connector  30  of the third embodiment are shape of the base unit  11 , shape of the spring body  12 , shape of the holding unit  13 , shape of the first contact  44 , and shape of the second contact  45  as illustrated in  FIG. 8A . In the connector  40  of the fourth embodiment, first of all, seen from the sides of the base unit  11 , the shape of the base unit  11  is W-character shape that height is small and width is horizontally long. And, two recesses  41 B and  42 B are formed on each inner surface of two concave parts in the base unit  11  so as to prevent the first contact  44  and the second contact  45  described later from releasing from the base unit  11 . The recesses  41 B and  42 B may be formed as one recess portion when boundary between the recesses  41 B and  42 B are took down. Moreover, concave parts  43  forming W-shape in the holding unit  13  are formed on the opposite surface to the base unit  11 . A recess further may be formed in the concave parts  43 . 
     As illustrated in  FIG. 8C , the side face of the base unit  11  and the side face of the holding unit  13  are connected with the spring body  12 . On the other hand, seen from the sides of the first contact  44  and the second contact  45 , the shape of the first contact  44  and the shape of the second contact  45  in the fourth embodiment each is formed in r-character shape. Each of the contact  44  and the contact  45  has three ends. The ends  44 A and  45 A correspond to the action parts of the contacts  14  and  15 , respectively. The ends  44 B and  45 B correspond to the sliding parts of the contacts  14  and  15 , respectively. The ends  44 C and  45 C correspond to the contact parts of the contacts  14  and  15 , respectively. 
     The contacts  44  and  45  in the fourth embodiment are fitted between the base unit  11  and the holding unit  13 . The ends  44 A and  45 A (action parts) are fitted in the concave parts  43  in the holding unit  13 . The ends  44 B and  45 B (sliding parts) are fitted in recesses  41 B and  42 B. As illustrated in  FIG. 8B , the ends  44 C and  45 C (contact parts) protrudes outside from the base unit  11 . The holding unit  13  and contacts  44  and  45  are made of conductive material as well as above-mentioned embodiments. 
     In the connector  40  of the fourth embodiment as illustrated in  FIG. 8D , when the ends  44 C and  45  C (contact parts) are pushed by the force “F” in vertical direction, the ends  44 B (sliding part) of the contact  44  and the ends  45 B (sliding part) of the contact  45  respectively move in the center of the base unit  11 . When the ends  44 A and  45 A (action parts) push the holding unit  13  by the movement of the ends  44 B and  45 B (sliding parts), the spring body  12  curves and thereby the holding unit  13  moves. In the fourth embodiment, the ends  44 B and  45 B (sliding parts) are fitted in the recesses  41 B and  42 B of the base unit  11 , and the ends  44 A and  45 A (action parts) are fitted in the concave parts  43  of the holding unit  13 . Therefore the contacts  44  and  45  do not easily release from the base unit  11  and the holding unit  13 . 
     According to the embodiments, the interposer includes a metal component which is used as an electrical path and a metal which is elastically deformed. And as the metal which is used as the electrical path is formed in small size, the interposer has a short electrical path. Thereby the IC package and the circuit board are connected at a short distance, and the structure is simple. As a result the interposer is manufactured at low cost. In addition, this interposer improves high reliability and signal quality of a component that large and a high-speed IC package is stacked and mounted on the circuit board via the interposer. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a illustrating of the superiority and inferiority of the invention. Although the embodiment(s) of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.