Abstract:
A contact member formed with a flat metal structure and an integrated elastomeric body. The contact member can be used to ground a printed circuit board (PCB) with a surrounding housing. The housing loads the contact member in a direction perpendicular to the face of the PCB. The elastomeric body supports the flat metal structure during repeated cycles of loading and unloading of the contact member. The elastic resiliency of the elastomeric body can help to reduce the effects of plastic deformation of the contact member, resulting in more reliable electrical connections a source outside of the PCB. And the elastomeric body does not require adhesive or separate fixing devices to hold it in place.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a contact member to be mounted on the surface of a printed circuit board and to achieve electrical conduction between a ground pattern on the printed circuit board and a grounding conductor. 
   BACKGROUND OF THE INVENTION 
   There is a conventionally known technique in which a contact member is mounted on the surface of a around pattern on a printed circuit board and, in that state, the printed circuit board is fixed in such a manner that the contact member is pressed against a grounding conductor, such as a chassis or the like. Thereby a ground pattern on the printed circuit board is electrically grounded to the grounding conductor via the contact member. Especially, in recent years, as more and more instruments having microcomputers built therein have been manufactured with the development of computer technology, the aforementioned technique is now indispensable for grounding printed circuit boards within such instruments. 
   This kind of contact member is likely to be formed by a conductive elastic sheet to ensure electrical conduction between a ground pattern on a printed circuit and a grounding conductor. Also, this contact member is sometimes combined with a conductive elastic body for the purpose of electromagnetic shield for use. 
   For example, in Publication of Japanese Unexamined Patent Application No. 2002-510873, situation is disclosed where a conductive gasket member is provided to a contact member made of plate metal in which a pair of spring-like finger parts are bent back from an end. 
   When a contact member is disposed between a ground pattern on a printed circuit and a grounding conductor such as a housing etc., tightening the cover of the housing by a bolt means risking that the contact member will be plastically deformed. This would result in the contact member losing its spring characteristics and not being able to elastically recover toward its original configuration. Once elastic resilience is lost, for example, when the housing is opened and closed repeatedly, the contact between the contact member and the housing may not be maintained, resulting in a chance of conductive failure. 
   The conductive gasket, disclosed in FIG. 10 of the Publication of Unexamined Japanese Patent Application No. 2002-510873, is considered by some to resist against the force which is attempting to crush a finger of the contact member. However, there is no reference in the above Japanese Patent Application to the problem of the case in which the elastic resilience of the finger is lost, and no description of measures to guard against the situation in which elastic resilience of the finger is lost. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to decrease the effect of plastic deformation of a contact member which is disposed between a ground pattern on a printed circuit board and a grounding conductor. 
   To attain the above and other objects, there is provided a contact member comprising a thin sheet member and an elastomeric body which may both be conductive and elastic. The thin sheet member includes a base part of which at least a portion is mounted on the surface of a ground pattern on a printed circuit board, a contact part which is provided facing the base part and becomes a joint area with a contact element on a surface providing a grounding conductor different from the printed circuit board on which the base part is mounted, and a supporting spring part which is connected to a part of the base part and to a base end of the contact part and which supports the contact part in such a manner that the contact part can be elastically deformed in the direction perpendicular to the plane of the base part. The elastomeric body is disposed between the base part and the contact part and is attached to the supporting spring part by allowing a part of the supporting spring part to penetrate through the inside of the elastomeric body. 
   A part of the base part is mounted on the surface of a ground pattern whereby this contact member is attached to a printed circuit board. By pressing a grounding conductor against the contact part provided facing the base part (for example, parallel to the base part), electrical conduction between a ground pattern on a printed circuit board and a grounding conductor is achieved. 
   The thin sheet member may preferably be composed of a single piece of sheet material. However, plural pieces of sheet material may be connected for use by spot welding or the like. The supporting spring part, which is connected to a part of the base part and to a base end of the contact part, supports the contact part in such a manner that the contact part can be elastically deformed in a direction perpendicular to the plane of the base part. Consequently, when the contact part is pressed by a grounding conductor, the contact part is elastically deformed in the direction of approaching the base part. The elastic repulsive force of the contact part caused by this deformation strengthens the contact between the contact part and a grounding conductor. As a consequence, the electrical conduction between a ground pattern and a grounding conductor can be favorably achieved. 
   When an external force is applied to elastically deform the contact part, the elastomeric body is elastically deformed. When the external force is released, the elastomeric body sustains an elastic recovery. Therefore, even if the force to elastically deform the contact part becomes excessive, the elastomeric body is a resistance against this force. As a result, it is avoided that the contact part is plastically deformed and that the spring characteristics of the contact part are lost. 
   In addition, even if the spring characteristics of the contact part are lowered and the recovery ability is decreased, the elastomeric body can compensate for the spring characteristics and provide a sufficient recovery ability. For this reason, if the spring characteristics of the contact part are lowered (or lost), the contact part can return toward its original configuration. Therefore, for example, when a housing is opened and closed repeatedly, the contact between the contact member and a grounding conductor is maintained, thus avoiding conductive failure. 
   Further in addition, the elastomeric body is attached to the supporting spring part by allowing a part of the support spring part to penetrate through the inside of the elastomeric body. As a result, for example, in spite of a repeated sequence of compression and release of the spring member, or other changes such as thermal expansion etc., there is little risk that the elastomeric body will be removed from the supporting spring part. In case of only using adhesive agents, there is a possibility that expansion and contraction changes may cause the adhesive agents to be removed. 
   Therefore it is not necessary to separately adhere the elastomeric body and the supporting spring part by adhesive agents or the like. Thus it is possible to use hard-to-adhere materials for the elastomeric body. Yet, the use of adhesive agents is not prohibited. Adhesive agents may be used based upon the material selections and operating environment of the elastomeric body. 
   In case of allowing a part of the supporting spring part to enter through the inside of the elastomeric body, the elastomeric body may be provided with a hole so that the entering part of the supporting spring part may pass through this hole. Alternatively, the elastomeric body may be provided with a groove deep enough that the entering part of the supporting spring part is contained, so that the supporting spring part may pass through this groove. 
   Also, a grounding conductor, which contacts and elastically deforms the supporting spring part, firstly abuts the supporting spring part, because the elastic body is only disposed between the base part and the supporting spring part. Therefore, the elastomeric body does not obstruct earth conduction between a grounding conductor and the supporting spring part. 
   Although it should be clear from this explanation, even though the elastomeric body may be made large enough to protrude beyond the base part or the contact part, it is preferable that the elastomeric body fits within the imaginary extended surfaces of the base part and of the contact part. 
   A basis of the material of the elastomeric body may be an elastomer. However, conductive particle and fiber such as filler etc. may be compounded therein for example. In case that conductive particles etc. are compounded into the elastomeric body or the like in order to achieve electrical conduction, the conductive distance between a ground pattern and a grounding conductor may become much shorter. 
   In the contact member, the elastomeric body is in contact with the contact part and the base part even in the state in which an external force needed to cause elastic deformation of the contact part is not applied to the contact member. As a result, when an external force which may elastically deform the contact part in the direction of the base part is subjected to the contact member, the external force immediately acts upon the elastomeric body as well. Therefore, the function of the elastomer body is performed more favorably. 
   In the contact member, the contact part comprises an attachment surface which can be grasped by an automatic mounting machine. This enables the contact member to be mounted on a printed circuit board using the automatic mounting machine. 
   In the contact member, the attachment surface and the base part are approximately parallel to each other in an unloaded state. Moreover, the attachment surface is set to maintain a substantially parallel relationship relative to the base part even when the contact part is elastically deformed in the direction of approaching the base part. Therefore, even if an elastic deformation is caused by abutment of the vacuum suction nozzle of the vacuum suction automatic mounting machine, gaps between the nozzle and the attachment surface are restrained. Because of this, the grasp of the contact member can be performed relatively efficiently. Thereby efficiency in the overall automatic mounting operation can be improved. 
   In the contact member, the elastomeric body is provided with a hollow part in a portion thereof under the contact part. 
   When the elastomeric body is compressively deformed, the hollow part provided to the elastomeric body in the portion under the contact part becomes a deformation allowing space for the elastomeric body. As a result, when the supporting spring part is elastically deformed in the direction that makes the contact part move closer to the base part, the initial resistance of the elastomeric body is decreased. In short, the ability to prevent the plastic deformation of the end portion of the contact part is enhanced because an excessive force is not applied by the elastomeric body to the supporting spring part and/or the contact part. 
   Preferably by allowing a portion of the elastomeric body located under the end part of the contact part to be the hollow part, an excessive force is inhibited from being applied to the end part of the contact part. As long as the hollow part is constructed so as to become the deformation allowing space when the elastic body is compressively deformed, the hollow part is not limited to a specific configuration and size. However, if the hollow part is configured to have a cavity in which at least one end is opened, the hollow part can be formed by injection molding. 
   In the contact member, the hollow part is preferably a longitudinal hole penetrating from the base part to the contact part. Therefore, the aforementioned effect of allowing injection molding, achieved by having a hollow shape in which at least one end is opened, can be obtained. 
   In the contact member, the hollow part is preferably a side hole penetrating along a direction perpendicular to the displacement direction of the supporting spring part when the supporting spring part is elastically deformed. This is the direction in which the contact part approaches and retreats from the base part. In addition, the ability to injection mold, achieved by having a hollow shape in which at least one end is opened, can be obtained. 
   Alternatively, in the early stage of the compressive deformation of the elastomeric body, the side hole is not greatly contracted. Thus, the resistance of the elastomeric body against this deformation is initially small, preferably helping to prevent excessive force from being applied to the supporting spring part as well as to the contact part, and also helping to reduce the amount of initial plastic deformation. On the other hand, if the compressive deformation of the elastomeric body continues to increase, whereby the side hole is substantially contracted, the resistance of the elastomeric body against the deformation force becomes much greater, thus preventing the excessive deformation (for example, crushing) of the supporting spring part. The function of inhibiting excessive deformation is valid for the contact part as well. 
   In the contact member of the present invention, at least a part of the base part is mounted on the surface of a ground pattern on a printed circuit board. This mounting is usually performed by soldering. Therefore, it is preferable that materials resistant to the heating caused by the soldering operation (generally a maximum temperature of about 260° C.) should be used for the elastomeric body. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1A  is a perspective view of a thin sheet member of a contact member according to a first embodiment of the invention; 
       FIG. 1B  is a top perspective view of the contact member according to the first embodiment of the invention; 
       FIG. 1C  is a bottom perspective view of the contact member shown in  FIG. 1B ; 
       FIG. 2A  is a cross sectional view taken along line IIA—IIA in  FIG. 1B  showing the state in which the contact member, according to the first embodiment of the invention, is mounted on a printed circuit board; 
       FIG. 2B  and  FIG. 2C  are explanatory views according to the first embodiment of the invention at the time that the deforming amount of the contact member is respectively small and large; 
       FIG. 3A  and  FIG. 3B  are a top perspective view and a bottom perspective view of the contact member according to a second embodiment of the invention; 
       FIG. 4A  is a cross sectional view according to the second embodiment of the invention showing the state in which the contact member is mounted on a printed circuit board; 
       FIG. 4B and 4C  are explanatory views according to the second embodiment of the invention at the time the deforming amount of the contact member is respectively small and large; 
       FIG. 5A  and  FIG. 5B  are a top perspective view and a bottom perspective view of the contact member according to a third embodiment of the invention; 
       FIG. 6A  is a cross-sectional view showing the state in which the contact member is mounted on a printed circuit board, according to the third embodiment of the invention; 
       FIG. 6B  is an explanatory view at the time the deforming amount of the contact member is small, according to the third embodiment of the invention; 
       FIG. 6C  is an explanatory view to show the case in which an elastomeric body without a hollow cavity is used for comparison; 
       FIG. 7  is a perspective view showing the entire appearance of the contact member according to a fourth embodiment of the invention; 
       FIG. 8A  is a plan view of the contact member according to the fourth embodiment of the invention; 
       FIG. 8B  is a side view of the contact member according to the fourth embodiment of the invention; 
       FIG. 8C  is a cross-sectional view taken along line IIIC—IIIC of the contact member according to the fourth embodiment of the invention; 
       FIG. 9A  is an explanatory view of the contact member according to the fourth embodiment of the invention; 
       FIG. 9B  is an explanatory view of the contact member of a comparative example without an elastomeric body for comparison; 
       FIGS. 10A ,  10 B and  10 C are explanatory views of modified examples of the thin sheet member; 
       FIGS. 11A ,  11 B,  11 C and  11 D are explanatory views of modified examples of the elastomeric body; 
       FIG. 12  is an explanatory view of modified examples of the elastomeric body; 
       FIGS. 13A and 13B  are graphs of a compressive and recovery experiment of the contact member according to the fourth embodiment of the invention; and 
       FIGS. 14A and 14B  are graphs of a compressive and recovery experiment of the contact member of a comparative example. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   [First Embodiment] 
   As illustrated in  FIGS. 1A ,  1 B, and  1 C, a contact member  70  comprises a thin sheet member  80  and an elastomeric body  90 . 
   The thin sheet member  80  may be made of plate metal (a material such as beryllium copper and phosphor bronze for example) and its thickness may be in the range of 0.3 mm to 0.8 mm. Known press operation, such as stamping out and bending or the like, is performed to the thin sheet member  80 . A base part  81 , a supporting spring part  82 , and a contact part  83  are provided thereto. 
   The base part  81  may have a substantially rectangular shape. In the middle area thereof, a longitudinal hole  81   a,  having a substantially rectangular shape, is formed by cutting and raising the supporting spring part  82  and the contact part  83 . Therefore, a joint surface  81   b,  which is to be soldered to a circuit pattern on a printed circuit board, is the undersurface of the surrounding area of the longitudinal hole  81   a.    
   The supporting spring part  82  is an incline connected to the base part  81  at one side of the longitudinal hole  81   a.  The end portion of the supporting spring part  82  is bent approximately parallel to the base part  81 , forming the flat contact part  83 . 
   The supporting spring part  82  can be elastically deformed in a direction causing the contact part  83  to move closer to the base part  81  (the joint surface  81   b ) or in the opposite direction about an area in which the supporting spring part  82  is connected to the base part  81 . The elastomeric body  90 , having a shape of a square frustum, is preferably a silicone elastomer which resists heating to 260° C. In the middle area thereof, is provided a side hole  91  having a shape of approximately a rectangular prism. The side hole  91  has openings at total three places; two places facing the sides perpendicular to the side of the longitudinal hole  81   a  connected to the supporting spring part  82 , and one place having an opening in the middle area of the longitudinal hole  81   a  at the undersurface of the elastomeric body  90 . 
   Also, as illustrated in  FIG. 2A , a joint hole  94  is provided in the elastomeric body  90 . The supporting spring part  82  penetrates through this joint hole  94  allowing the elastomeric body  90  to be attached to the thin sheet member  80 . 
   Moreover, the bottom of the elastomeric body  90  fits within the longitudinal hole  81   a.  This also enables the combination of the elastomeric body  90  with the thin sheet member  80 . 
   This contact member  70  is mounted for use on a printed circuit board  60  as illustrated in  FIGS. 2A ,  2 B, and  2 C. An attachment surface, more specifically, the upper surface of the contact part  83  (along with the upper surface  92  of the elastomeric body  90 ), is grasped by means of a vacuum suction automatic mounting machine in order to convey the contact member  70 . This contact member  70  is disposed onto the printed circuit board  50  in such a manner that a joint surface  81   b  is in contact with solder paste located on a circuit pattern. The solder paste is melted by reflow soldering and cooled. Thereby, the contact member  70  is soldered to the printed circuit board  50 . In  FIGS. 2A ,  2 B, and  2 C, the circuit pattern  51  and the solder paste  51   a  disposed between the joint surface  81   b  and the printed circuit board  50  are not shown in order to simplify the figures. 
   In the contact member  70  mounted onto the surface of the printed circuit board  50  in the aforementioned manner, the contact part  83  is pressed against a grounding conductor  60 , such as a housing or the like, by the closing of the housing accommodating the printed circuit board  50 . 
   The distance between the printed circuit board  50  and the grounding conductor  60  interposing the contact member  70  therebetween is set to be smaller than the height of the contact member  70  when it is not subjected to an external force. Consequently, a pressing force from the assembled grounding conductor  60  is applied to the contact part  83 . 
   Because of this pressing force, as shown in  FIG. 2B , the supporting spring part  82  is elastically deformed in such a manner that it rotates around the connecting part between the supporting spring part  82  and the base part  81 . Additionally, this pressing force acts upon the elastomeric body  90  either through the supporting spring part  82  and the contact part  83 , or directly, resulting in the elastic deformation of the elastomeric body  90  as though it were crushed. 
   The pressing force applied to the contact part  83  acts upon the elastomeric body  90  as well, so that the elastomeric body  90  adds to the resistance and the contact member  70  is not excessively deformed. Therefore, even if the force to elastically deform the contact member  70  becomes excessive as in the case above, the contact part  83  and the supporting spring part  82  avoid being only plastically deformed and losing a great deal of their spring characteristics. 
   When the elastomeric body  90  is elastically deformed in this way, the side hole  91  becomes a deformation allowing space for the elastomeric body  90 . As a result, when the supporting spring part  82  is elastically deformed in the direction that drives the contact part  83  closer to the base part  81 , the resistance of the elastomeric body  90  is initially decreased. In short, because an excessive force is not applied by the elastomeric body  90  to the supporting spring part  82  and the contact part  83 , the ability to inhibit the plastic deformation of these parts is enhanced. 
   Also, when the amount of elastic deformation of the contact member  70  by a pressing force is small (at the early stage of deformation) as illustrated in  FIG. 2B , the existence of the side hole  91  facilitates the deformation of the elastomeric body  90 , thus allowing the elastomeric body  90  to be deformed as shown with little force. 
   When the amount of deformation is large, as illustrated in  FIG. 2C , the inner walls of the side hole  91  come into contact with each other. Thus, the elastic repulsive force of the elastomeric body  90  gets larger than before and provides support for the contact part  83  as well as for the supporting spring part  82 . Therefore, the elastomeric body  90  inhibits these parts from being deformed beyond the elastic limit; in other words, plastic deformation of the supporting spring part  82  and the contact part  83  is suppressed. 
   Although the elastomeric body  90  is disposed on the upper side of the base part  81 , the grounding conductor  60 , which elastically deforms the contact member  70 , firstly abuts the contact part  83  (and the upper face  92  of the elastomeric body  90 ). Therefore, the elastomeric body  90  does not disturb the electric contact between the grounding conductor  60  and the contact part  83 . 
   After the grounding conductor  60  is removed from the contact member  70  and the pressing force is released by the opening of the housing or the like, the elastomeric body  90  goes through an elastic recovery. Accordingly, even if the spring characteristics of the supporting spring part  82 , which was deformed by the pressure of the grounding conductor  60 , are lowered and the recovery ability of the supporting spring part  82  is decreased, the elastomeric body  90  compensates for the lost spring characteristics and provides a sufficient recovery ability. For this reason, even if the spring characteristics of the thin sheet member  80  are decreased (or lost), the contact part  83  can return toward its original state. Therefore, for example, when the housing is opened and closed repeatedly, the contact between the contact member  70  and the grounding conductor  60  is maintained, inhibiting conductive failure 
   Furthermore, as the elastomeric body  90  is attached to the supporting spring part  82  by allowing a part of the supporting spring part  82  to penetrate into the joint hole  94 , there is relatively no risk that the elastomeric body  90  is unintentionally removed from the supporting spring part  82  (in short, from the entire thin sheet member  80 ) because of either adhesion failure or deterioration of an adhesive. There is no need to separately adhere the elastomeric body  90  and the supporting spring part  82  with an adhesive or the like, so it is possible to use hard-to-adhere materials for the elastomeric body  90 . 
   In the present embodiment, such a configuration is adopted that the elastomeric body  90  is in contact with the contact part  83  and the base part  81  even in the state in which an eternal force, which would cause the contact member  70  to be elastically deformed, is not applied to the contact member  70 . Consequently, when an external force, which would cause the contact part  83  to be elastically deformed in the direction of the base part  81 , is applied, it is immediately applied to the elastomeric body  90  as well. 
   Such a configuration may also be adopted that the elastomeric body  90  is in contact with neither the contact part  83  nor the base part  81  in an unloaded state. In this configuration, after the contact part  83  is displaced toward the base part  81  by more than a predetermined amount, the external force of the elastic deformation is applied to the elastomeric body  90  as well. By doing this, for example, when the amount of displacement of the contact part  83  (and/or the amount of elastic deformation of the supporting spring part  82 ) is small, only the elastic repulsive force of the thin sheet member  80  maintains the abutting conduction between the contact part  83  and the grounding conductor  60 . Subsequently, the elastomeric body  90  inhibits the amount of elastic deformation of the supporting spring part  82  which would be considered excessive. 
   Furthermore, the upper surface of the contact part  83  of the contact member  70  in the present embodiment is flat. This upper surface becomes an attachment surface that can be grasped with an automatic mounting machine. Therefore, the flat upper surface is grasped by the automatic mounting machine, allowing the contact member  70  to be automatically mounted on the printed circuit board  50 . In this respect, since the upper surface  92  of the elastomeric body  90  may also be used as an attachment surface, some deviation of the grasping position by the automatic mounting machine does not cause problems with respect to grasping. 
   [Second Embodiment] 
   The second embodiment uses an elastomeric body (the same type of material as in the first embodiment) having a side hole similar to the first embodiment; however, the configuration of the side hole is different from the first embodiment. 
   As illustrated in  FIGS. 3A , and  3 B, and  FIGS. 4A ,  4 B, and  4 C, the configuration of a side hole  101  provided to an elastomeric body  100  of the second embodiment is substantially a trapezoid. The present embodiment is similar to the first embodiment except for primarily this point. Accordingly, the components with the same configurations are denoted with the same reference numerals as in the first embodiment, and a description of the same components may not be repeated. 
   As illustrated in  FIGS. 3A and 3B , an elastomeric body  100  of the present embodiment comprises a side hole  101 . The side hole  101  is in the shape of approximately a trapezoid, and has openings at three places; two places facing the sides perpendicular to the side of the longitudinal hole  81   a  connected to the supporting spring part  82 , and one place having an opening in the middle area of the longitudinal hole  81   a  at the undersurface of the elastomeric body  100 . 
   The elastomeric body  100  comprises an upper surface  92  which is identical to the first embodiment. In the joint hole  94 , that is also the same as in the first embodiment, the elastomeric body  100  is connected to the supporting spring part  82  This contact member  70  is mounted on a printed circuit board  50  for use as in the first embodiment (refer to  FIGS. 4B and 4C ). In  FIGS. 4A ,  4 B, and  4 C, the circuit pattern  51  and the solder paste  51   a  disposed between the joint surface  81   b  and the printed circuit board  50  are not shown in order to simplify the figures. After the contact member  70  is mounted on the surface of the printed circuit board  50 , the contact part  83  is pressed against a grounding conductor  60 , such as a housing or the like, by the closing of the housing accommodating the printed circuit board  50  (refer to  FIGS. 4B  and C). 
   The distance between the printed circuit board  50  and the grounding conductor  60 , interposing the contact member  70  therebetween, is set to be smaller than the height of the contact member  70  (measured from a joint surface  81   b  to an upper surface of the contact part  83 ) when the contact member  70  is not subjected to an external force. Consequently, a pressing force from the grounding conductor  60  is applied to the contact part  83 . 
   As illustrated in  FIG. 4B , because of this pressing force, the supporting spring part  82  is elastically deformed in such a manner that it collapses around a connecting part between the supporting spring part  82  and the base part  81 . Additionally, this pressing force acts upon the elastomeric body  100  either through the supporting spring part  82  and the contact part  83 , or directly, resulting in the elastic deformation of the elastomeric body  100  as if the elastomeric body  100  were crushed. 
   The pressing force applied to the contact part  83  acts upon the elastomeric body  100  as well, so that the elastomeric body  100  adds to the overall resistance and the result is that the contact member  70  is not excessively deformed. Therefore, even if the force to elastically deform the contact member  70  becomes excessive as in the situation above, the contact part  83  and the supporting spring part  82  can avoid being only plastically deformed and losing the spring characteristics. 
   When the elastomeric body  100  is elastically deformed in this manner, the side hole  101  becomes a deformation allowing space for the elastomeric body  100 . As a result, when the supporting spring part  82  is elastically deformed in a direction that brings the contact part  83  closer to the base part  81 , the resistance of the elastomeric body  100  is initially slight. In short, the effect to inhibit the plastic deformation of the parts is enhanced, because excessive force is applied to neither the supporting spring part  82  nor the contact part  83 . 
   Also, when the amount of elastic deformation of the contact member  70  is small (at an early stage of deformation by pressing) as illustrated in  FIG. 4B , the existence of the side hole  101  facilitates the deformation of the elastomeric body  100 , thus allowing it to be deformed as shown in  FIG. 4B  with relatively little force. In this state, the end part of the contact part  83  engages the elastomeric body  100 , resulting in an elastic repulsive force being generated in the elastomeric body  100  and suppressing the excessive deformation of the contact member  70 . 
   When the amount of deformation is increased as illustrated in  FIG. 4C , the side hole  101  is mostly contracted and the elastomeric body  100  starts shifting from elastic deformation to compressive deformation. This makes the elastic repulsive force of the elastomeric body  100  larger than initially in order to support the contact part  83  and the supporting spring part  82 . Consequently, the elastomeric body  100  inhibits these parts from being permanently deformed over the elastic limit; in other words, the effects of plastic deformation of the supporting spring part  82  and the contact part  83  are suppressed. 
   Although the elastomeric body  100  is disposed on the upper side of the base part  81 , the grounding conductor  60 , which elastically deforms the contact member  70 , firstly abuts the contact part  83  (and the upper face  92  of the elastomeric body  100 ). Therefore, the elastomeric body  100  does not disturb the electric contact between the grounding conductor  60  and the contact part  83 . 
   After the grounding conductor  60  is removed from the contact member  70  and the pressing force is released by the opening of the housing or the like, the elastomeric body  100  recovers elastically. Accordingly, even if the spring characteristics of the supporting spring part  82 , which is deformed by the pressure of the grounding conductor  60 , are lowered and the recovery ability of the spring part  82  is decreased, the elastomeric body  100  compensates for some of the lost spring characteristics and provides a sufficient recovery ability. For this reason, if the spring characteristics of the thin sheet member  80  are decreased (or lost), the contact part  83  can return sufficiently close to its original state. Therefore, for example, when the housing is opened and closed repeatedly, the contact between the contact member  70  and the grounding conductor  60  is maintained, inhibiting conductive failure. 
   Furthermore, as the elastomeric body  100  is attached to the supporting spring part  82  by having a part of the supporting spring part  82  penetrate into the joint hole  94 , there is no risk that elastomeric body  100  will be removed from the supporting spring part  82  (or, the thin sheet member  80 ) because of adhesion failure or the deterioration of an adhesive. There is no need to additionally adhere the elastomeric body  100  and the supporting spring part  82  with separate adhesive or the like, so it is possible to use hard-to-adhere materials for the elastomeric body  100 . 
   In the present embodiment, a configuration is adopted that the elastomeric body  100  is in contact with the contact part  83  and the base part  81  even in the state in which an eternal force, which would cause the contact member  70  to be elastically deformed, is not applied to the contact member  70 . Consequently, when the external force, which would result in the contact part  83  being elastically deformed in the direction of the base part  81 , is applied, the external force is immediately applied to the elastomeric body  100  as well. 
   However, such a configuration may also be adopted that the elastomeric body  100  is in contact with neither the contact part  83  nor the base part  81  in the state in which an external force, necessary to cause elastic deformation, is not applied to the contact member  70 . Only when the contact part  83  is displaced toward the base part  81  by more than a predetermined amount, the external force of the elastic deformation will be applied to the elastomeric body  100  as well. By using this configuration, for example, when the amount of displacement of the contact part  83  (and/or the amount of elastic deformation of the supporting spring part  82 ) is small, only the elastic repulsive force of the thin sheet member  80  maintains the abutting conduction between the contact part  83  and the grounding conductor  60 . Subsequently, the elastomeric body  100  primarily inhibits the amount of elastic deformation of the supporting spring part  82  that is excessive. 
   Furthermore, the upper surface of the contact part  83  in the present embodiment is flat. This surface becomes an attachment surface that can be grasped with an automatic mounting machine. This flat surface is grasped by the automatic mounting machine, allowing the contact member  70  to be mounted onto the printed circuit board  50 . In this situation, the upper surface  92  of the elastomeric body  100  may also become an attachment surface, so that some deviation of the grasping position by the automatic mounting machine does not result in problems. 
   [Third Embodiment] 
   The third embodiment uses an elastomeric body (with the same type of material as in the first embodiment) having a longitudinal hole. The components with the same configurations are denoted with the same reference numerals and the description of these components may not be repeated due to similarities and descriptions of the first embodiment. 
   As illustrated in  FIGS. 5A , and  5 B, and  FIGS. 6A ,  6 B, and  6 C, an elastomeric body  110  of the third embodiment is provided with a cylindrically configured longitudinal hole  111 . The longitudinal hole  111  has a bottom opening in the area defined by the longitudinal hole  81   a.  While the longitudinal hole  111  may have an open top and the top reaches the undersurface of the contact part  83 , in this embodiment the top of the longitudinal hole  111  is not opened thoroughly. About half of the diameter of the open top is covered by the flat upper surface  92 , which lies along the same plane as the upper surface of the contact part  83 . 
   The elastomeric body  110  is connected to the supporting spring part  82  by a joint hole  94  which is identical to the first embodiment. This contact member  70  is also mounted on a printed circuit board  50  for use as in the first embodiment (refer to  FIG. 6B ). In  FIGS. 6A ,  6 B, and  6 C, the circuit pattern  51  and the solder paste  51   a  disposed between the joint surface  81   b  and the printed circuit board  50  are not shown in order to simplify the figures. For the contact member  70  mounted on the surface of a printed circuit board  50  in this manner, the contact part  83  is pressed against a grounding conductor  60 , such as a housing or the like, by the closing of the housing accommodating the printed circuit board  50 . 
   The distance between the printed circuit board  50  and the grounding conductor  60 , interposing the contact member  70  therebetween, is set to be smaller than the height of the contact member  70  (as measured from a joint surface  81   b  to the upper surface of the contact part  83 ) when the contact member  70  is not subjected to an external force. Consequently, a pressing force from the grounding conductor  60  is applied to the contact part  83 . 
   As illustrated in  FIG. 6B , because of this pressing force, the supporting spring part  82  is elastically deformed in such a manner that it collapses around a connecting part located between the supporting part  82  and a base part  81 . Additionally, this pressing force acts upon the elastomeric body  110  either through the supporting spring part  82  and the contact part  83 , or directly, resulting in elastic deformation of the elastomeric body  110  as it is crushed. 
   The pressing force applied to the contact part  83  acts upon the elastomeric body  110  as well, so that the elastomeric body  110  adds to the resistance and the contact member  70  is not excessively deformed. Therefore, even if the force to elastically deform the contact member  70  becomes excessive as described above, the result is avoided that the contact part  83  and the supporting spring part  82  are non-recoverably plastically deformed and that the spring characteristics of the parts are lost. 
   When the elastomeric body  110  is elastically deformed in this way, the longitudinal hole  111  becomes a deformation allowing space for the elastomeric body  110 . As a result, when the supporting spring part  82  is elastically deformed in the direction that makes the contact part  83  closer to the base part  81 , the resistance of the elastomeric body  110  is initially small. Consequently, the effect to inhibit plastic deformation is enhanced because excessive force is not applied to the supporting spring part  82  and the contact part  83 . Especially since the underside of the end part of the contact part  83  is positioned over the longitudinal hole  111 , thus preferably inhibiting excessive force being applied to the end part of the contact part  83  (i.e., potentially resulting in deformation of this part). 
     FIG. 6C  shows the case in which an elastomeric body  120 , without the longitudinal hole  111 , is used for comparison. In this case, the repulsive force of the elastomeric body  120  is generated in the direction so that the contact part  83  is bent away or spread apart from the supporting spring part  82 . Thus, there is a risk that the bend forming the joint between the contact part  83  and the supporting spring part  82  is spread out and plastically deformed. 
   Although the elastomeric body  110  is disposed on the upper side of the base part  81 , the grounding conductor  60 , which elastically deforms the contact member  70 , firstly abuts the contact part  83  (and the uppersurface  92  of the elastomeric body  110 ). Therefore, the elastomeric body  110  does not disturb the electric contact formed between the grounding conductor  60  and the contact part  83 . 
   After the grounding conductor  60  is removed from the contact member  70  and the pressing force is released by the opening of the housing or the like, the elastomeric body  110  experiences an elastic recovery. Accordingly, even if the spring characteristic of the supporting spring part  82 , which is deformed by the pressure of the grounding conductor  60 , is lowered and the recovery ability is decreased, the elastomeric body  110  can compensate for some of the lost spring characteristics and provide a sufficient recovery ability. For this reason, even if the spring characteristic of the thin sheet member  80  is decreased (or lost), the contact part  83  can return sufficiently toward its original state. Therefore, for example, when the housing is opened and closed repeatedly, the contact between the contact member  70  and the grounding conductor  60  is maintained, thus inhibiting conductive failure. 
   Furthermore, as the elastomeric body  110  is attached to the supporting spring part  82  by using a part of the supporting spring part  82  penetrating into the joint hole  94  as a securing means, there is no risk that elastomeric body  110  is removed from the supporting spring part  82  (or, the thin sheet member  80 ) solely because of adhesion failure or the deterioration of an adhesive. It is not necessary to provide additional securing means between the elastomeric body  110  and the supporting spring part  82 , such as with an adhesive or the like, so it is possible to use hard-to-adhere materials for the elastomeric body  110 . 
   In the present embodiment, a configuration is adopted such that the elastomeric body  110  is in contact with the contact part  83  and the base part  81  even in an unstressed state. Consequently, when the external force, which causes the contact part  83  to be elastically deformed toward the base part  81 , is applied, it is immediately applied to the elastomeric body  110  as well. 
   A configuration may also be adopted such that the elastomeric body  110  is in contact with neither the contact part  83  nor the base part  81  in the state in which an external force able to cause elastic deformation is not applied to the contact member  70 . In this configuration, when the contact part  83  is displaced to the base part  81  by more than a predetermined amount, the external force of the elastic deformation is only then applied to the elastomeric body  110  as well. By doing this, for example, when the amount of displacement of the contact part  88  (and/or the amount of elastic deformation of the supporting spring part  82 ) is small, only the elastic repulsive force of the thin sheet member  80  maintains the abutting connection between the contact part  83  and the grounding conductor  60 . Subsequently, the elastomeric body  110  of this configuration only inhibits the amount of deformation of the supporting spring part  82  that is excessive. 
   Furthermore, the upper surface of the contact part  83  of the present embodiment is flat, which allows it to become an attachment surface that can be grasped with an automatic mounting machine. Therefore, this flat surface is subsequently grasped by the automatic mounting machine, allowing the contact member  70  to be mounted upon the printed circuit board  50 . On this occasion, as the upper surface  92  of the elastomeric body  110  may also become an attachment surface, small deviations of the grasping position with the automatic mounting machine does not cause any problems. 
   [Fourth Embodiment] 
   As illustrated in  FIG. 7  and  FIGS. 8A ,  8 B, and  8 C, a contact member  1  is shown which comprises a thin sheet member  10  and an elastomeric body  40 . 
   A thin sheet member  10  is made up of plate metal (i.e., a material such as beryllium copper and phosphor bronze), and its thickness is in the range of 0.3 mm to 0.8 mm. Known press operations such as stamping out and bending are performed to the thin sheet member  10 . A base portion  11 , a supporting spring portion  21 , and a contact portion  31  are provided thereto. 
   The base part  11  is in an approximately rectangular shape, and includes a concave portion  11   b  in a middle area of the base part  11  in its width direction. Both areas to the side of this concave portion  11   b  are flat shaped and are referred to as joint surfaces  11   a.  The joint surfaces  11   a  are soldered onto a circuit pattern on a printed circuit board. 
   One end of the base part  11  is curved in an arc, while the other end is bent back in the direction opposing a joint surface  11   a,  forming a U-shape. This bending part  11   c  becomes a joint part with the supporting spring part  21 . 
   The entire supporting spring part  21  is an extremely gentle curve (the radius of curvature is relatively large). The supporting spring part  21  is bent in such a manner that the distance between the supporting spring part  21  and the base part  11  becomes greater as the supporting spring part  21  moves away from the bending part  11   c.  The supporting spring part  21  is also bent in such a manner that the inclination of the supporting spring part  21  relative to the base part  11  becomes gentler as the supporting spring part  21  approaches its terminal part. An edge  21   b  of the supporting spring part  21  is bent back in the direction of the base part  11 , substantially forming a semicircle. 
   Then, a middle area of the supporting spring part  21  in the width direction (i.e., the direction shown by X in  FIG. 8A ) is cut and raised to form the contact part  31 . The contact part  31  has a width approximately equal to one-third of the total width of the supporting spring portion  21  and is disposed in the direction opposite to the base part  11 . 
   A contact part  31  comprises a connected part  31   a,  which is connected to the terminal part of the supporting spring part  21  and inclined in a direction away from the base part  11 , a flat part  31   b  which is bent down from the connected part  31   a  and extends substantially parallel to the base part  11  (the joint surface  11   a ), and a free end part  31   c  which is bent further down from the flat part  31   b  and inclined in a direction toward the base part  11 . The connected area between the connected part  31   a  and the supporting spring part  21  is referred to as a base end part α; the terminal of the free end part  31   c  is referred to as a free end. 
   Also, by cutting and raising the contact part  31 , a substantially rectangular longitudinal hole  21   a  is formed in the middle area of the supporting spring part  21 . The elastomeric body  40  is preferably a silicone elastomer which resists heating at 260° C. and has a cross section in the form of an elliptical bar like body. A deep slot  41  is provided to both end surfaces of the elastomeric body  40  as partially illustrated in  FIG. 8C . 
   The elastomeric body  40  is disposed so as to be sandwiched between the base part  11  (the upper surface of the concave part  11   b ) and the contact part  31  (the under surface of the flat part  31   b ). 
   A part of the supporting spring part  21  enters the deep slot  41  of the elastomeric body  40 , thereby attaching the elastomeric body  40  to the supporting spring part  21 , i.e. the thin sheet member  10 . Also, the elastomeric body  40  is positioned directly under the contact part  31 ; however, the elastomeric body  40  is connected to neither the contact part  31  nor the base part  11  (it is not adhesively joined or the like). 
   This contact member  1 , as illustrated in  FIG. 9A , is mounted on a printed circuit board  50  for use. More specifically, the contact member  1  is movably held by the upper surface (attachment surface) of the flat part  31   b  being grasped by the vacuum suction of an automatic mounting machine. That contact member  1  is then disposed upon the printed circuit board  50  in such a manner that the joint surfaces  11   a  are provided onto a solder paste  51   a  on the printed circuit board  50 . The solder paste  51   a  is subsequently melted by reflow soldering and cooled, thereby soldering the contact member  1  to the printed circuit board  50 . 
   In the contact member  1  mounted on the surface of the printed circuit board  50  in the aforementioned manner, the flat part  31   b  is pressed against the grounding conductor  60 , for example a housing or the like, by the closing of the housing accommodating the printed circuit board  50 . 
   The distance between the printed circuit board  50  and the grounding conductor  60 , interposing the contact member  1  therebetween, is set to be smaller than the height of the contact member  1  when the contact member  1  is not subjected to an external force. Consequently, a pressing force from the grounding conductor  60  is applied to the flat part  31   b.    
   Because of this pressing force, the contact part  31  is elastically deformed around the base end part α, while the supporting spring part  21  is elastically deformed around the bending part  11   c.  In this situation, the flat part  31   b  is displaced while maintaining a substantially parallel relationship relative to the joint surfaces  11   a.  Additionally, this pressing force acts upon the elastomeric body  40  as well through the contact part  31 , resulting in the elastic deformation of the elastomeric body  40  as if it were subject to a crushing type of force.  FIG. 9A  shows the state in which the contact part  31 , the supporting spring part  21 , and the elastomeric body  40 , are all elastically deformed using chain double-dashed lines. 
     FIG. 9B  shows the state in which the elastomeric body  40  is not provided (illustrating with chain double-dashed lines the state in which the contact part  31  and the supporting spring part  21  are elastically deformed). In the case shown in  FIG. 9A , unlike in the case shown in  FIG. 9B , the pressing force applied to the contact part  31  acts upon the elastomeric body  40  as well, so that the elastomeric body  40  provides resistance and the contact member  1  is not excessively deformed. Therefore, even if the force to elastically deform the contact part  31  becomes excessive as shown above, the contact part  31  is inhibited from being plastically deformed and losing its spring characteristics. 
   The grounding conductor  60 , which contacts the contact part  31  and elastically deforms this, firstly abuts the contact part  31  (specifically the flat part  31   b ), because the elastomeric body  40  is sandwiched between the base part  11  and the contact part  31 . Therefore, the elastomeric body  40  does not disrupt the electric contact between the grounding conductor  60  and the contact part  31 . 
   After the grounding conductor  60  is removed from the flat part  31   b  and the pressing force is released by the opening of the housing or the like, the elastomeric body  40  undergoes an elastic recovery. Accordingly, even if the spring characteristics of the contact part  31 , which is deformed by the pressure of the grounding conductor  60 , are reduced and the recovery ability is decreased, the elastomeric body  40  can compensate for the spring characteristics and provide a sufficient recovery ability. For this reason, if the spring characteristics of the contact part  31  are decreased (or lost), the contact part  31  can sufficiently return toward the original state. Therefore, for example, when the housing is frequently opened and closed, the contact between the contact member  1  and the grounding conductor  60  is maintained, inhibiting conductive failure. 
   Furthermore, there is no risk that elastomeric body  40  is unintentionally or accidentally removed from the supporting spring part  21  (i.e., the thin sheet member.  10 ) because of either adhesion failure or deterioration of an adhesive for example, because the elastomeric body  40  is attached to the supporting spring part  21  by causing a part of the supporting spring part  21  to penetrate the deep slot  41  within each end of the elastomeric body  40 . There is no need to supplemently adhere the elastomeric body  40  and the supporting spring part  21  with an adhesive or similar substance, so it is possible to use hard-to-adhere materials for the elastomeric body  40 . 
   Meanwhile, in the present embodiment, such a configuration is adopted that the elastomeric body  40  is in contact with the contact part  31  and the base part  11  even in the state in which the eternal force, which causes the contact part  31  to be elastically deformed in the direction of the base part  11 , is not applied to the contact member  1 . Consequently, when the external force is applied, it is immediately applied to the elastomeric body  40  as well. 
   Such a configuration may also be adopted that the elastomeric body  40  is in contact with neither the contact part  31  nor the base part  11  when the contact member  1  is unstressed, and that after the contact part  31  is elastically displaced in the direction of the base part  11  by more than a predetermined amount, the external force of the elastic deformation is applied to the elastomeric body  40  as well. For example, when the amount of elastic deformation of the contact part  31  is small, only the elastic repulsive force of the thin sheet member  10  maintains the abutting connection between the contact part  31  and the grounding conductor  60 . Subsequently, the elastomeric body  40  only inhibits when the elastic deformation of the contact part  31  becomes excessive. 
   In addition, the contact part  31  of the contact member  1  of the present embodiment is provided with the flat part  31   b  which also functions as an attachment surface that can be grasped with an automatic mounting machine. Therefore, when the flat part  31   b  is grasped by an automatic mounting machine, the contact member  1  can be mounted on the printed circuit  50 . 
   Further in addition, the flat part  31   b  and the joint surface  11   a  are approximately parallel to each other in the condition ill which the external force able to cause elastic deformation of the contact part  31  is not applied to the contact member  1 . Even when the contact part  31  is elastically deformed in a direction that makes the free end part  31   c  approach the base part  11 , the flat part  31   b  is able to maintain a substantially parallel relationship relative to the joint surface  11   a.  Therefore, even when elastic deformation is caused by abutment onto a vacuum suction nozzle of the vacuum suction automatic mounting machine, gaps between the nozzle and the flat part  31   b  are restrained. The grasp of the contact member  1  can be thereby performed effectively and the efficiency in the automatic mounting operation can be improved. 
   [Comparative Experiment] 
   The contact member  1  of the fourth embodiment and a contact member of a comparative example, which does not include the elastomeric body  40  and is only composed of the thin sheet member, are used for illustrative comparison. The comparison involves loading a contact part  31  (a flat part  31   b ) and measuring the recovery ability. The results are illustrated in  FIG. 13A  (the contact of the embodiment) and in  FIG. 14A  (the contact of the comparative example).  FIG. 13B  and  FIG. 14B  are graphs of loading (compressive force). 
   It is clear from the comparison between  FIG. 13A  and  FIG. 14A  that the contact member  1  of the embodiment has a higher recovery rate from compressive deformation. 
   [Modified Example of a Thin Sheet Member] 
   In the aforementioned fourth embodiment, the width of the middle area of a longitudinal hole  21   a  in its longitudinal direction is substantially the same as the width of the flat part  31   b  of a contact part  31 . As a modification of this, as illustrated in  FIG. 10A , a supporting spring part  22  may be provided with a longitudinal hole  22   a  having a width wider than that of the flat part  31   b  of the contact part  31 . 
   Also, in the aforementioned fourth embodiment, the contact part  31  is formed by cutting and raising a portion of a supporting spring part  21 ; however, a contact part may also be formed as an extension of the supporting spring part and bent from the terminal part thereof. More particularly, as shown in  FIG. 10B , a contact part  33  may be formed by bending an extension back from an end part  23   b  of a supporting spring part  23  in the direction opposite to a base part  13 . Alternatively, as shown in  FIG. 10C , an end  24   b  of a supporting spring part  24  may be bent around in the direction of a base part  14 , thereby forming a contact part  34 , which has a connected part  34   a  penetrating through a longitudinal hole  24   a  of the supporting spring part  24 . 
   [Modified Example of an Elastomeric Body] 
   In the above described fourth embodiment, an elastomeric body  40  whose cross section is approximately elliptical is used; however, the cross section thereof maybe circular ( FIG. 11A ), oval ( FIG. 11B ), square or rectangular ( FIG. 11C ), and polygonal ( FIG. 11(   d )) or a combination of any of the above. 
   Also, as shown in  FIG. 12 , it is possible to adopt such a configuration that approximately the whole space inside of the thin sheet member  10  may be filled with an elastomeric body  40  (hatching is performed for clarification). 
   All of the embodiments described may be used without separate fastening or adhering techniques. But this does not imply that the use of such techniques is prohibited within the scope of this invention, but only implies that they are not required. 
   In addition, specific types of material, shapes and/or configurations were described in an attempt to enable the embodiments of the invention. The scope of this invention includes combinations of geometric figures described as well as all obvious variations thereof, including but not limited to, the use of material with multiple densities and spring rates, conductive materials, cavities, holes, and other variations known or accepted by people skilled in the art. 
   The invention is not restricted to the embodiment as described above, and may be practiced or embodied in still other ways without departing from the subject matter thereof.