Patent Publication Number: US-7905730-B2

Title: Interposer with a pair of contact points

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date under 35 U.S.C. §119(a)-(d) of Japanese Patent Application No. 2007-337624, filed Dec. 27, 2007. 
     FIELD OF THE INVENTION 
     The present invention relates to a contact that is capable of mating with terminals, such as an electric circuit board and semiconductor bumps, and an interposer having an insulator in which the contact is mounted. 
     BACKGROUND 
     Currently, there is a probing test that measures an electric characteristic on two or more semiconductor chips, which are formed on a semiconductor wafer in such a way that a contact may quickly link with a terminal, such as lands or balls arranged on semiconductor chips. These contacts are known, including an electro conductive rubber, a so-called Pogo pin, a stamping spring produced by a die cutting processing, and a ring spring with an electroformed pipe. In the probing test, an interposer has an insulator, in which such contacts are mounted. 
     U.S. Pat. No. 5,573,435 discloses such a contact, wherein two independent unclosed loops are connected. The loops are prepared through a die cutting process. The proposed contact has a design that allows for high elasticity and low resistance, as well as low self-inductance in the low spring constant. 
     Moreover, the &#39;435 reference proposes a connection body (contact) formed using a MEMS (Micro Electro Mechanical System) process (refer to Japanese Patent Publication TokuHyou 2006-514289, for instance). The contact, proposed by Japanese Patent Publication TokuHyou 2006-514289, has a first contact section where one end meets a semiconductor bump, a connection section that is C shaped and extending continuously from the other end to the one end of the first contact section, a support section that is connected with one end of the connection section and has a convex shape, and a second contact section that is inserted into an electric circuit board and has an O shape extending continuously from one end of the support section. The proposed contact may be prepared using micro processing, such as the MEMS process. Particularly, it is possible to prepare one end of the first contact section through micro processing, the first contact section that meets the semiconductor bump. Preparing the proposed first contact through die cutting section would be difficult to implement. 
     However, a contact prepared from electro-conductive rubber is inferior in durability. A contact that consists of Pogo-pin and the ring spring is inferior in the contact reliability. Moreover, a contact that consists of the stamping spring is difficult to implement miniaturization, because there is a limit in micro processing, and it is inferior in high density mounting and handling a high-speed signal. 
     According to the contact proposed by U.S. Pat. No. 5,573,435, two unclosed loops are formed, but are independent of each other. The amount of displacement is relatively small and the contact pressure increases in an interposer where the contact is mounted on the insulator. 
     It is difficult to minimize the shape of the proposed contact, especially considering that the two independent loops connect. However, it is necessary to reduce the loop in order to achieve maximum displacement and the low contact pressure. Moreover, since the connected structure of two independent loops is a structure joined in the center section, connection might broken when the contact is under a lateral load. Moreover, there is a problem in that the contact is inferior in a high-density mounting and high-speed signal to the insulator, because the contact is the one produced by a die cutting process. 
     According to the contact proposed by Japanese Patent Publication TokuHyou 2006-514289, an interposer, wherein the contact is mounted on an insulator, the amount of displacement depends only on a cantilever beam of a connection section. Accordingly, it is necessary to increase the thickness of the contact, for instance 100 μm or more, to obtain a large amount of displacement (to obtain a prescribed spring load). However, it is known that it takes a long time to form a contact having a thickness of 100 μm using the MEMS process, as much as 10 hours. 
     SUMMARY 
     In view of the foregoing, it is an object of the present invention, among others, to provide a contact which has high durability and reliability, all the while the contact being capable of applying a high-density mounting on the insulator, and also capable of handling high-speed signals. 
     The contact includes a spring section that is formed as a single closed loop of material, prepared from Ni alloy. The loop may be subjected to force at different points along the loop, to cause elastic deformation. The contact having a pair of contact points, formed in such a way that the contact points project outwardly at positions separated from one another, each contact point positioned about half way around the loop of the spring section. Each contact point capable of meeting with a terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in greater detail in the following with reference to embodiments, referring to the appended drawings, in which: 
         FIG. 1  is a perspective view of an interposer according to a first embodiment of the present invention; 
         FIG. 2  is a plan view of the interposer according to the first embodiment of the present invention; 
         FIG. 3  is a front view of the interposer according to the first embodiment of the present invention; 
         FIG. 4  is a right side view of the interposer according to the first embodiment of the present invention; 
         FIG. 5  is an enlarged sectional view of a portion in which a contact is mounted on a housing of an interposer according to a second embodiment of the present invention; 
         FIG. 6  is an enlarged sectional view of a portion in which a contact is mounted on a housing of an interposer according to a third embodiment of the present invention; 
         FIG. 7  is an enlarged sectional view of a portion in which a contact is mounted on a housing of an interposer according to a fourth embodiment of the present invention; 
         FIG. 8  is an enlarged sectional view of a portion in which a contact is mounted on a housing of an interposer according to a fifth embodiment of the present invention; 
         FIG. 9  is an enlarged sectional view of a portion in which a contact is mounted on a housing of an interposer according to a sixth embodiment of the present invention; 
         FIG. 10  is a plan view of the interposer according to a seventh embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Embodiment(s) 
     Embodiments of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a perspective view of an interposer according to a first embodiment of the present invention.  FIG. 2  is a plan view of the interposer according to the first embodiment of the present invention. A part (a) of  FIG. 2  is a plan view. A part (b) of  FIG. 2  is a front view. A part (c) of  FIG. 2  is a right side view. 
       FIG. 3  is an enlarged sectional view taken along the line A-A line of  FIG. 2 .  FIG. 4  is an enlarged sectional view taken along the line B-B line of  FIG. 2 . Incidentally, for the sake of convenience of the explanation,  FIG. 3  additionally shows a pad  31  of an circuit board  30  and a semiconductor ball  40 . 
     An interposer  1  is composed of a contact  10  and a housing  20  of an insulator where the contact  10  is mounted. 
     The contact  10  is provided with a spring section  11  and a pair of contact points  12  ( 121 ,  122 ). The contact  10  corresponds to a first embodiment of the present invention. The contact  10  is for instance one that consists of the Ni alloy, such as Ni—Co and Ni—Mn (for instance, Hv450-Hv600), and is produced using a micro-process technique that combines photolithography and electroforming, which is well known. Therefore, a contact  10  thickness of 50 μm or less is achieved. In the embodiment shown, the thickness is assumed to be about 20 μm. Additionally, the contact  10 , prepared from a Ni alloy, is extremely resistant to abrasion and has high durability. 
     The spring section  11  of the contact  10  is formed as a single closed loop of material, which is prepared from Ni alloy. The loop is capable of being subjected to force at different points, thus causing elastic deformation. The spring section  11 , as a result, is approximately gourd-shaped having narrow portions  111  that mutually approach an axis connecting a pair of contact points  12  ( 121 ,  122 ). 
     A pair of contact points  12  ( 121 ,  122 ) of the contact  10  are formed in such a way that the contact points  121  and  122  project outwardly at positions, separated from one another, each contact point  121 ,  122  about half way around the loop of the spring section  11 . Moreover, each tip of the contact points  12  ( 121 ,  122 ) are formed using a micro-process technique, to prepare a circular arc of radius 30 μm or less. For instance, each tip has a circular arc of about 5 μm in the embodiment shown. Each contact point  121 ,  122  is capable of contacting an associated terminal. For instance, in the embodiment shown, the contact point  121 ,  122  contacts a pair of terminals, such as a pad  31  of a circuit board  30  and a semiconductor ball  40 . 
     According to the contact  10  of the first embodiment, when a pair of contact points  12  ( 121 ,  122 ) meet with a terminal, it is possible to achieve high concentrated stress, even in case of a low load, such as low touching pressure. Accordingly, even if contamination (pollutant) or an insulation film form on the surface of the terminal, a pair of contact points  12  ( 121 ,  122 ) may overcome the contamination or insulation film through the high concentrated stress. Thus, it is possible to obtain excellent contact resistance with the terminal. Moreover, the contact  10  of the first embodiment is of a shape, which is different from the shape of a conventional contact where the amount of displacement depends only on a cantilever beam shaped connection section. IN the proposed contact, it is possible to obtain an amount of displacement that is larger than that of the conventional contact without increasing the thickness of the contact  10 . Additionally, even in a case where the thickness is 20 μm, for instance, the contact  10  can be produced at lower costs than a conventional contact. 
     According to the contact  10  of the first embodiment, the spring section  11  is formed as a single closed loop. This feature allows the contact  10  to remain connected when receiving a lateral load, which is different from the conventional contact, wherein two contact points are connected by positioning the contact member in between the two contact points. It is possible to maintain contact  10  structure and function. Moreover, the contact  10  is formed using a micro-process technique, which combines photolithography and electroforming, in such a way that the contact points  12  ( 121 ,  122 ) are very sharply formed, like a circular arc. In the embodiment shown, the contact points ( 121 ,  122 ) have minute radii of 5 μm. In such a design, it is possible to obtain higher concentrated stress, even with low contact pressure. Therefore, according to the contact  10  of the first embodiment, it is possible to provide a contact having high durability and contact reliability. 
     The contact  10  of the first embodiment is very small, being prepared using the micro process-technique. This makes it possible to achieve high-density mounting between the contact  10  and the housing  20 . The design of the narrow portions  111  facilitates this process. Moreover, the use of the very small contact  10  makes it possible to conduct a high-speed signal because the electrical length is shortened. 
     The housing  20  has a thickness that is thicker than the length of the narrow portions  111 , in a direction extending to the contact points. However, the housing  20  is thinner than a distance between the pair of contact points  12  ( 121 ,  122 ). The housing  20  has two or more circular penetration holes  21  and slits  22 , each having a space larger than the thickness of the contact  10 . The slits  22  each penetrate two or more penetration holes  21 , which are formed on a surface  20   a  and extending to a back  20   b  of the housing  20 . The slits  22  extend parallel to the surface  20   a  and the back  20   b  of the housing. According to the contact  10  of the embodiment shown, the narrow portions  111  are positioned in a central part of the penetration hole  21 . Furthermore, the housing surface  20   a  and back  20   b  are mounted in such a way that the one contact point  121  and the other contact point  122  projected from the associated slits  22  respectively, including the portions which are adjacent to the one contact point  121  and the other contact point  122  of the spring section  11  respectively. The housing  20  has a board support body  23  that supports the mounted contact  10 . 
     Therefore, the interposer  1  of the first embodiment has high durability, and is high in the contact reliability, and is capable high density mounting. Further, the interposer  1  is capable of handling a high-speed signal. According to the interposer  1 , the posture of the contact  10 , which is mounted on the housing  20 , is stabilized by the slit  22 . 
     Next, a second embodiment of the interposer of the present invention will be described. 
     Incidentally, the following second embodiment is one in which the contact  10 , which is a component of the interposer  1  of the first embodiment mentioned above, is replaced with a contact  50  which is shaped differently than the contact  10  of the first embodiment. 
     In the following figures, the same parts are denoted by the same reference numbers as those of  FIGS. 1 to 4 . Redundant explanation will be omitted. It explains only the difference point with the first embodiment. 
       FIG. 5  is an enlarged sectional view of a portion in which the contact  50  is mounted on the housing  20  of the interposer  2 , according to the second embodiment of the present invention. 
     The interposer  2  comprises the contact  50  and the housing  20  of an insulator, where the contact  50  is mounted. 
     The contact  50  has a spring section  51  and a pair of contacts  52  ( 521 ,  522 ). The contact  50  corresponds to the second embodiment of a contact of the present invention. 
     The spring section  51  of the contact  50  is formed as a single closed loop of material, which is prepared from Ni alloy. The loop may be subjected to force, which causes elastic deformation. Moreover, the spring  51  is substantially gourd-shaped having narrow portions  511 , which are narrowed in the direction that mutually approach an axis drawn between a pair of contact points  52  ( 521 ,  522 ), wherein an upper portion and a lower portion of the loop each have an arrow shape. 
     A pair of contact points  52  ( 521 ,  522 ) of the contact  50  are formed in such a way that the contact points  521  and  522  project outwardly at positions, separated from one another, each contact point  521 ,  522  about half around of the loop of the spring section  51 . The pair of contacts  52  ( 521 ,  522 ) are capable of meeting with an associated terminal. 
     The interposer  2  of the second embodiment, in which the substantially gourd-shaped contact  50  is mounted, and designed in much the same way as the interposer  1  of the first embodiment, has high durability and contact reliability. Further, the interposer  2  is capable of high density mounting, and handling a high-speed signal. 
     Next, there will be explained a third embodiment of the interposer of the present invention. 
     Incidentally, the following third embodiment is one in which the contact  10 , which is the component of the interposer  1  of the first embodiment mentioned above, is replaced with a contact  60 , which is different in shape from the contact  10  of the first embodiment. 
     In the following figures, the same parts are denoted by the same reference numbers as those of  FIGS. 1 to 4 . Redundant explanation will be omitted. It explains only the difference point with the first embodiment. 
       FIG. 6  is an enlarged sectional view of a portion in which a contact  60  is mounted on the housing  20  of an interposer  3  according to a third embodiment of the present invention. 
     The interposer  3  comprises the contact  60  and the housing  20  of an insulator, where the contact  60  is mounted. 
     The contact  60  has a spring section  61  and a pair of contacts points  62  ( 621 ,  622 ). The contact  60  corresponds to the third embodiment of the present invention. 
     The spring section  61  of the contact  60  is formed as a single closed loop of material, which is also prepared from Ni alloy. The loop may be subjected to force at different points, causing elastic deformation. Moreover, the spring section  61  is gourd-shaped, having narrow portions  611  that are narrowed in a direction that mutually approach at an axis drawn between a pair of contact points  62  ( 621 ,  622 ). The loop shape of spring section  61 , while divided into two by an axis that connects a pair of contact points  62  ( 621 ,  622 ), is a non-symmetric shape. 
     A pair of contact points  62  ( 621 ,  622 ) of the contact  60  are formed in such a manner that the contacts  621  and  622  project outwardly at positions separated from one another, each contact point  621 ,  622  positioned about half way around the loop of the spring section  61 . The pair of contacts  62  ( 621 ,  622 ) are capable of meeting with an associated terminal. 
     According to the interposer  3  of the third embodiment, wherein the loop shape of the spring section is non-symmetric shape, one side and the other side of the spring section  61  are distorted and transformed when a pair of contact points  62  ( 621 ,  622 ) meets and comes in contact with the associated terminal. As a result, a pair of contact points  62  ( 621 ,  622 ) move in a horizontal direction to meet the terminal, so that wiping action is established. Thus, according to the interposer  3  of the third embodiment, even if contamination (pollutant) or an insulation film is formed on the surface of the terminal, the pair of contact points  62  ( 621 ,  622 ) overcome the contamination or insulation film by the wiping action. Hence, the design improves contact resistance with the terminal, as well as contact reliability. The interposer  3  of the third embodiment, similar to the interposer  1  of the first embodiment, has high durability, and is capable of high density mounting. Further, the interposer  3  is capable of handling a high-speed signal. 
     Next, there will be explained a fourth embodiment of the interposer of the present invention. 
     Incidentally, the following fourth embodiment is one in which the contact  10 , which is the component of the interposer  1  of the first embodiment mentioned above, is replaced with a contact  70  that is shaped differently than the contact  10  described in the first embodiment. 
     In the following figures, the same parts are denoted by the same reference numbers as those of  FIGS. 1 to 4 . Redundant explanation will be omitted. It explains only the difference point with the first embodiment. 
       FIG. 7  is an enlarged sectional view of a portion in which the contact  70  is mounted on the housing  20  of the interposer  4 , according to a fourth embodiment of the present invention. 
     The interposer  4  comprises the contact  70  and the housing  20  of an insulator where the contact  70  is mounted. 
     The contact  70  has a spring section  71  and a pair of contact points  72  ( 721 ,  722 ). The contact  70  corresponds to the fourth embodiment of the present invention. 
     The spring section  71  of the contact  70  is formed as a single closed loop of material, which is prepared from Ni alloy. The loop may be subjected to force at different points, causing elastic deformation. Moreover, the spring section  71  is a gourd-shaped, having narrow portions  711  that are narrowed in a direction that mutually approach an axis drawn between a pair of contact points  72  ( 721 ,  722 ). The loop shape of spring section  71 , when divided into two by an axis connecting a pair of contact points  72  ( 721 ,  722 ), creates sectional shapes that are mutually different. 
     The pair of contact points  72  ( 721 ,  722 ) of the contact  70  are formed in such a way that the contact points  721  and  722  project outwardly at positions separated from one another, each contact point  721 ,  722  about half way around the loop of the spring section  71 . The pair of contacts  72  ( 721 ,  722 ) are capable of meeting with an associated terminal. 
     According to the interposer  4  of the fourth embodiment, the loop shape of the spring section is non-symmetric shape, wherein one side and the other side of the spring section  71  are distorted and transformed when a pair of contact points  72  ( 721 ,  722 ) meets and comes into contact with the associated terminal. Similar to the interposer  3  of the third embodiment, one side and the other side of the spring section  71  are distorted and transformed when a pair of contacts  72  ( 721 ,  722 ) meet with an associated terminal. As a result, a pair of contact points  72  ( 721 ,  722 ) moves in the horizontal direction in order to meet with the terminal, so that wiping action is established. Thus, according to the interposer  4  of the fourth embodiment, even if contamination (pollutant) or an insulation film is formed on the surface of the terminal, the pair of contact points  72  ( 721 ,  722 ) overcome the contamination or insulation film by wiping action, thus improving contact resistance with the terminal. As a result, the contact  70  is extremely high in contact reliability. The interposer  4  of the fourth embodiment, similar to the interposer  1  of the first embodiment, has high durability, and is capable of high density mounting. Further, the interposer  4 , according to the fourth embodiment, is capable of handling a high-speed signal. 
     Next, there will be explained a fifth embodiment of the present invention. 
     Incidentally, the following fifth embodiment is one in which the contact  10  and the housing  20 , that are components of the interposer  1  of the first embodiment mentioned above, are replaced respectively with a contact  80  and a housing  210  that are different from the contact  80  and the housing  210  in the shape. 
       FIG. 8  is an enlarged sectional view of a portion in which the contact  80  is mounted on the housing  210  of an interposer  5 , according to a fifth embodiment of the present invention. 
     The interposer  5  comprises the contact  80  and the housing  210  of an insulator, where the contact  80  is mounted. 
     The contact  80  has a spring section  81  and a pair of contact points  82  ( 821 ,  822 ). The contact  80  corresponds to the fifth embodiment of the present invention. 
     The spring section  81  of the contact  80  is formed as a single closed loop of material, which is prepared from Ni alloy. The loop is round shaped, yet capable of elastic deformation through force. 
     A pair of contact points  82  ( 821 ,  822 ) of the contact  80  are formed in such a way that the contact points  821  and  822  project outwardly at positions separated from one another, each contact point  821 ,  822  about half way around the loop of the spring section  81 . The pair of contact points  82  ( 821 ,  822 ) are capable of meeting with an associated terminal. 
     The housing  210  has thickness that is thinner than the distance between the pair of contact points  82  ( 821 ,  822 ). The housing  210  has a pair of plate members  212  that include formed slits  211 , which cause one contact point  821  and the other contact point  822  to project through the plate member  212 , respectively. According to the contact  80 , the one contact point  821  and the other contact point  822  enter the slits  211 , and the contact  80  is mounted in such a manner that the one contact point  821  and the other contact point  822  projected from the associated slits  211 , respectively, including the portions which are adjacent to the one contact  821  and the other contact  822  of the spring section  81 , respectively. 
     The interposer  5  of the fifth embodiment, in which the round contact  80  is mounted, is similar to the interposer  1  of the first embodiment, in that the interposer  5  has high durability and contact reliability, and is capable of high density mounting. Additionally, the interposer  5  of the fifth embodiment is capable of handling a high-speed signal. 
     Next, there will be explained a sixth embodiment of the interposer of the present invention. 
     Incidentally, the following sixth embodiment is one in which the contact  10  and the housing  20 , that are the components of the interposer  1  of the first embodiment mentioned above, are replaced with a contact  90  and a housing  220  that are different from the contact  10  and the housing  20  in shape. 
       FIG. 9  is an enlarged sectional view of a portion in which the contact  90  is mounted on the housing  220  of an interposer  6 , according to the sixth embodiment of the present invention. 
     The interposer  6  comprises the contact  90  and the housing  220  of an insulator where the contact  90  is mounted. 
     The contact  90  has a spring section  91  and a pair of contact points  92  ( 921 ,  922 ). The contact  90  corresponds to the sixth embodiment of the present invention. 
     The spring section  91  of the contact  90  is formed is formed as a round single closed loop, which may be subjected to force in order to cause elastic deformation. 
     A pair of contact points  92  ( 921 ,  922 ) of the contact  90  are formed in such a way that the contact points  921  and  922  project outwardly at positions separated from one another, each contact point  921 ,  922  about half way around the loop of the spring section  91 . The pair of contact points  92  ( 921 ,  922 ) capable of meeting with an associated terminal. 
     The housing  220  has a thickness that is thinner than the distance between the pair of contact points  92  ( 921 ,  922 ). The housing  220  has a pair of plate members  222  having formed slits  221 , which cause one contact point  921  and the other contact point  922  to project through the plate members  222 , respectively. According to the contact  90 , the one contact point  921  and the other contact point  922  enter the slits  221 , and the contact  90  is mounted in such a way that the one contact point  921  and the other contact point  922  project through the associated slits  221 , respectively, including the portions which are adjacent to the one contact point  921  and the other contact point  922  of the spring section  91 , respectively. 
     The interposer  6  of the sixth embodiment, in which the substantially round contact  90  is mounted, and similar to the interposer  1  of the first embodiment, has high durability and contact reliability, and is capable of high density mounting. Further, the interposer  6  of the sixth embodiment is capable of handling a high-speed signal. 
     Next, there will be explained a seventh embodiment of the interposer of the present invention. 
     Incidentally, the following seventh embodiment is one in which the housing  20 , that is the component of the interposer  1  of the first embodiment mentioned above, is replaced with a housing  220  which is different from the housing  20  in the shape. 
     In the following figures, the same parts are denoted by the same reference numbers as those of  FIGS. 1 to 4 . Redundant explanation will be omitted. It explains only the difference point with the first embodiment. 
       FIG. 10  is a plan view of the interposer  7 , according to a seventh embodiment of the present invention. 
     The interposer  7  comprises the contact  10  and the housing  230  of an insulator where the contact  10  is mounted. 
     The housing  230  has thickness that is thicker than the narrow portions  111 , but is thinner than the distance between a pair of contact points  12  ( 121 ,  122 ). The housing  230  has a rectangular parallelepiped shape. Two or more contacts  10  are arranged on a two-dimensional basis. Slits  231  are prepared within the housing  230 , so that the slits  231  diagonally extend toward a side of the rectangular shape of the housing  230 , as shown by a plane view of  FIG. 10 . 
     The interposer  7 , similar to the interposer  1  of the first embodiment, has high durability and is capable of high density mounting, as well as the ability to handle a high-speed signal. 
     The contacts, according to the embodiments as mentioned above, can be applied also to a test socket of a semiconductor testing device and a connection between high density substrates beside the interposer. 
     Moreover, the interposer, according to the embodiments as mentioned above, can be prepared through high density mounting for use in ultrasonic diagnostic equipment for medical treatment, such as CT, MRI, and NMR equipment, as well as devices for probing tests that measures an electric characteristic. 
     The interposers of the first through fourth embodiments are explained by way of example enumerating such a case where the housing has two or more penetration holes and slits. However, it is possible that the housing, referred to in the present invention, may have a board support body that has thickness corresponding to the length of the narrow portions of the contact, and has a penetration hole that the narrow portion enters. 
     As mentioned above, and according to the present invention, it is possible to provide a contact wherein the contact has high durability and contact reliability, and is further capable of high density mounting and handling of a high-speed signal. 
     While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by those embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and sprit of the present invention.