Contact in electric part socket

Abstract: A contact in an electric part socket has a first spring portion, a second spring portion spaced apart from the first spring portion but connected to it at both basal and distal ends thereof, a terminal portion continuously leading to the connected portion between the basal ends and adapted to be brought into contact with a wiring board or the like, and a mount contact portion formed on the connected portion between their distal ends and adapted to be brought into contact with a terminal of an electric part to be mounted on it. The first and second spring portions are flexed about the connected portion between the basal ends in order to displace the mount contact portion downward. The mount contact portion is pressure contacted with the terminal of the electric part mounted on it by reaction of the first and second spring portions.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a contact to be used for contacting with a terminal of an electric part such as IC package. 2. Description of the Prior Art A conventional contact 1, as shown in Fig. 9, often used in a socket for IC, etc. comprises a supporting portion 2 extending in a horizontal direction, a terminal portion 3 extending downward continuously from the supporting portion 2 in order to be contacted with a circuit board or the like, a spring portion 4 disposed above the supporting portion in such a manner as to be continuous therefrom and curved into a horizontal generally U-shape, and a mount contact portion 5 formed on a free end of the spring portion in order to exert a vertical resiliency thereto and adapted to mount thereon an external terminal of IC, the mount contact portion 5 being displaced downward while flexing the U-shaped spring portion 4 when the terminal of an electric part is mounted thereon and pressure is exerted thereto, so that the mount contact portion 5 would be pressure contacted with the terminal of the electric part by reaction thereof. In recent years, with the development of electronics technique, a small size of an IC socket is demanded. Furthermore, miniaturization of a contact in an IC socket and of an external terminal of IC is progressed, and as a result, realization of a reliable contact relation therebetween is increasingly demanded at present. However, the conventional contact of the type that a terminal of an electric part is mounted thereon in order to obtain an electric contact relation therebetween had such shortcomings that when the horizontal U-shaped spring portion is displaced in a vertical direction against its resiliency in order to exert contact pressure to the mount contact portion, the mount contact portion is disconnected from the external terminal of IC because the mount contact portion has such components as to be excessively displaced forward and backward while itself displacing downward. Since the space for accommodating the horizontal generally U-shaped spring portion is limited, even if the configuration of the spring portion is changed in order to reduce the amount of displacement of the mount contact portion in the forward and backward direction, control of the displacement of the mount contact portion in the forward and backward direction owing to the change in configuration thereof is necessarily limited. Also, a conventional IC package called TAB package had such shortcomings that since an external terminal thereof is a Cu foil which is soft, strength thereof is very weak and when the mount contact portion of the contact is displaced in an upward or downward direction, it is moved forward and backward while itself being friction contacted with the Cu foil, to cause the weak external terminal to be deformed. US-A-4,832,617 discloses a contact in accordance with the preamble of Claim 1. SUMMARY OF THE INVENTION It is therefore a general object of the present invention to provide a contact in an electric part socket capable of obviating the above-mentioned shortcomings. A specific object of the present invention is to provide a contact of the type that a terminal of an electric part such as IC or the like is mounted on a mount contact portion formed on a distal end of a spring portion to displace the spring portion downward in order to obtain a contact pressure owing to reaction thereof, wherein displacement of the mount contact portion is effectively made, and displacing components of the mount contact portion in a forward and backward direction can be controlled to a necessary range with ease when the mount contact portion is displaced downward. The invention provides a contact in accordance with Claim 1. With the above constitution, when downward force is exerted to the mount contact portion upon placement of a terminal of an electric part thereon, the first and second spring portions are flexed downward together to cause the mount contact portion to displace downward, and the mount contact portion is pressure contacted with the terminal of the electric part mounted thereon by reaction of the first and second spring portions. When the first and second spring portions are flexed downward together or when they are restored upward together, they mutually control a forward or backward movement, so that the mount contact portion can be displaced downward almost in a vertical direction. Otherwise, by appropriately determining configuration, dimension and arrangement of the first and second spring portions, an amount of displacement of the mount contact portion in a forward or backward direction can be controlled to a limited range with ease. According to the present invention, by effectively restraining or removing excessive displacing components of the mount contact portion in a forward or backward direction, the problem of a mount contact portion being disconnected from a minute terminal of an electric part and the problem of a terminal of a TAB package being damaged can be effectively prevented. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a contact according to one embodiment of the present invention; Fig. 2 is a side view of the above contact; Fig. 3 is a side view showing a displacing state of the above contact; Fig. 4 is a side view of a contact according to another embodiment of the present invention; Fig. 5 is a side view of a contact according to a further embodiment of the present invention; Fig. 6 is a side view of a contact according to a still further embodiment of the present invention; Fig. 7 is a side view of a contact according to a yet further embodiment of the present invention; Fig. 8 is a side view of a contact according to additional embodiment of the present invention; and Fig. 9 is a side view of the conventional contact. DETAILED DESCRIPTION OF THE EMBODIMENTS One embodiment of the present invention will be described with reference to Figs. 1 through 3 inclusive. The numeral 11 denotes a contact to be embedded in an electric part socket. The contact 11 has an inverse T-shaped supporting portion formed of a supporting portion 12a extending in a lateral direction and a vertical supporting portion 12b rising from the portion 12a. Preferably, the lateral supporting portion 12a is extended in a generally horizontal direction, and the vertical supporting portion 12b is risen in a generally vertical direction from a position one sided toward a rear end of the lateral supporting portion 12a. The supporting portion 12 is connected to a first linear spring portion 14 and a second linear spring portion 15 extending in a lateral direction by an equal length from the vertical supporting portion 12b. Accordingly, the first and second spring portions 14 and 15 are located in higher position than the horizontal supporting portion 12a, and the first spring portion 14 is located in higher position than the second spring portion 15 and spaced apart preferably in parallel relation from the second spring portion 15. The basal ends of the first and second spring portions 14 and 15 are interconnected through the vertical supporting portion 12b, and the distal ends thereof are interconnected through the mount contact portion 16. Accordingly, the vertical supporting portion 12b of the supporting portion 12 forms the connected portion between the basal ends of the first and second spring portions, and the mount contact portion 16 forms the connected portion between the distal ends of the first and second spring sections. On the one hand, the mount contact portion 16 interconnects the first and second spring portions 14 and 15, and on the other hand, it is extended in the vertical direction, an upper end thereof projecting upward from the front end of the first spring portion 14 to form a contact end portion 16a, an end face of the contact end portion 16a being served as a mount contact point 16c with respect to a terminal of an electric part to be mounted thereon. Accordingly, the mount contact portion 16 has at its lower part a connected portion 16b for interconnecting the first and second spring portions 14 and 15, and at its upper part the contact end portion 16a. The first and second spring portions 14 and 15 are so designed in configuration of a spring and in sectional configuration that resiliency of the first and second spring portions 14 and 15 would be equal. Further, a connecting configuration of the contact supporting portion 12 with respect to the vertical supporting portion 12b is identical with a connecting configuration of the contact supporting portion 12 with respect to the mount contact portion 16. A terminal portion 13 extends downward from the lateral supporting portion 12a in order to be contacted with a wiring board or the like. As is shown in Fig. 3, when an electric part's terminal 18 is mounted on the mount contact point 16c and pressure is exerted to the mount contact point 16c from above, the first and second spring portions 14 and 15 are displaced from the positions shown by the broken lines to the positions shown by the full lines against resiliency thereof. Reaction of the first and second spring portions 14 and 15 exerts contacting force directing upward to the mount contact portion 16, i.e., mount contact point 16c so that the mount contact point 16c would be pressure contacted to the electric part's terminal 18. In case spring constants of the first and second spring portions 14 and 15 are set to be equal at the time the above displacement is given, each connected portion of the first and second spring portions 14 and 15 to each mount contact portion 16 is displaced in a same direction by an equal distance with respect to the connected portion to each vertical supporting portion 12b. As a result, the mount contact portion tion 16 is displaced almost in a vertical direction, and displacing components of the first and second spring sections 14 and 15 in a forward and backward direction are removed or minimized. Figs. 4 and 5 show other embodiments. In Fig. 4, the first spring portion is formed shorter than the second spring portion 15. As a result, upon downward displacement of the mount contact point 16c of the mount contact portion 16, each connected portion of the first and second spring portions 14 and 15 with respect to the mount contact portion 16 is displaced in a different direction by a different distance. Actually, the connected portion 16d of the first spring portion 14 to the mount contact portion 16 is displaced backward by a greater degree than the connected portion 16e of the second spring portion 15 to the mount contact portion 16. This means that the mount contact portion 16 is displaced downward including a backward displacing component. As a result, the mount contact point 16c is displaced backward by a limited dimension at the same time the mount contact point 16c is being displaced downward. An amount of this backward displacement can be determined to a value within a range of, for example, an area of an electric part's terminal by appropriately setting the lengths of the first and second spring portions. In Fig. 5, the first spring portion 14 is formed longer than the second spring portion 15. As a result, upon downward displacement of the mount contact point 16c of the mount contact portion 16, each connected portion of the first and second spring portions 14 and 15 with respect to the mount contact portion 16 is displaced by a different distance in a different direction. Actually, the connected portion of the second spring portion 15 to the mount contact portion 16 is displaced backward by a greater degree than the connected portion of the first spring portion 14 to the mount contact portion 16. This means that the mount contact portion 16 is displaced downward including a forward displacing component. As a result, the mount contact point 16c is displaced forward by a limited dimension at the same time the mount contact point 16c is being displaced downward. An amount of this forward displacement can be restricted to a necessary minimum by selecting a difference in length between the first and second spring portions. In the embodiments shown in Figs. 4 and 5, an excessive displacement of the mount contact point 16c in the forward and backward direction can be restrained, and an amount of displacement of the mount contact point 16c in the forward and backward direction, which is required for friction with the electric part's terminal 18 as mentioned above, can be controlled by setting the above lengths. Besides the above, by changing various factors which exert affection to resiliency of the first and second spring portions 14 and 15, such as sectional configurations, positional relation, material, length, etc. of the first and second spring portions 14 and 15 which are not shown, an intended downward displacement can be obtained while freely controlling displacing components of the mount contact point 16c, such as component of a forward displacement, component of a backward displacement and the like, without increasing the size of a contact, that is, without increasing the size of a socket. Fig. 6 shows a further embodiment, in which the supporting portion 12 of the contact 11 is not provided with the vertical supporting portion 12b, and the basal ends of the first and second spring portions 14 and 15 are connected to the lateral supporting portion 12a. At this time, the first spring portion 14, which is located in a higher position, may be provided at a basal end portion thereof with a supporting piece 19 having high rigidity as shown by imaginary lines of Fig. 6 in order to make the spring lengths of the first and second spring portions 14 and 15 as equal as possible. The first and second spring portions 14 and 15 have a curved portion at basal end portions thereof, respectively, and are connected to the lateral supporting portion 12a through this curved portion. In a still further embodiment of Fig. 7, the first and second spring portions 14 and 15 are interconnected at distal end portions thereof and are connected to the mount contact portion 16. Furthermore, Fig. 8 shows a yet further embodiment of the present invention, in which the first and second spring portions 14 and 15 are curved in an opposing direction with respect to each other so that they exhibit a convex curve respectively and are extended in a lateral direction. This embodiment also includes a constitution wherein only one of the spring portions 14 and 15 is curved. As suggested in this embodiment, the first and second spring portions 14 and 15 may take various other shapes than the curved-shape between the connected portion at the basal end portions thereof and the connected portion at the distal end portions thereof. The present invention includes the embodiments shown in Figs. 4 through 8 in addition to the embodiment shown in Figs. 1 through 3 and also includes other modified embodiments of a mount contact type contact suggested by these embodiments. As described in the foregoing, a contact in an electric part socket according to the present invention includes a first spring portion, a second spring portion spaced apart from the first spring portion but connected thereto at both basal and distal ends thereof, a terminal portion continuously leading to the connected portion between the basal ends and adapted to be brought into contact with a wiring board or the like, and a mount contact portion formed on the connected portion between the distal ends and adapted to be brought into contact with a terminal of an electric part to be mounted thereon, said first and second spring portions being flexed about the connected portion between the basal ends in order to displace the mount contact portion downward, said mount contact portion being pressure contacted with the terminal of the electric part mounted thereon by reaction of said first and second spring portions. Accordingly, since the first and second spring portions mutually control a forward or backward movement when they are flexed downward together or when they are restored upward together, the mount contact portion can be displaced downward almost in a vertical direction. Otherwise, by forming a difference in length, width, etc. of the first and second spring portions, an amount of displacement thereof in a forward or backward direction can be controlled to a limited range with ease. That is, by effectively restraining or removing excessive displacing components of the mount contact portion in a forward or backward direction, the problem of a mount contact portion being disconnected from a minute terminal of an electric part and the problem of a terminal of a TAB package being damaged can be effectively prevented. According to the present invention, displacement of a mount contact point can be freely controlled without increasing the size of a socket, and as a result, it becomes easy to design a contact which is hardly displaced with respect to an external terminal of a miniaturized IC. Furthermore, since displacement of the mount contact point in a forward and backward direction can be controlled, an amount of displacement of the mount contact point can be limited to a necessary range. As a result, by effecting a wiping action in order to obtain a stable electric contact relation, oxide skins of the mount contact point and external terminal of IC can be wiped out with ease.

Claims: A contact for use in a socket for receiving an electric part, said contact comprising: a first spring portion (14); a second spring portion (15) spaced apart from said first spring portion; a basal end connecting portion (12b) connected between basal ends of said spring portions; a distal end connecting portion (16b) connected between distal ends of said spring portions; a terminal portion (12) connected to the basal end connecting portion (16b) and adapted to be brought into contact with a wiring board or the like; and a contact end portion (16a) on said distal end connecting portion; characterized in that said contact end portion (16a) extends from said distal end connecting portion in the direction of an extension of an imaginary line passing through the connection points (16d,16e) of the first and second spring portions (14,15) with the distal end connecting portion (16b) and is disposed above the distal end connecting portion (16b); and said distal end connecting portion (16b) is connected by said first and second spring portion (14,15) to said basal end connecting portion (12b) such that the locus of movement of the contact end portion (16a) is substantially parallel to said line, when a contact point (16c) on the free end of said contact end portion (16a) is contacted, in use, by a terminal of an electric part inserted into the socket, in order to maintain contact between said contact point (16c) and the terminal. A contact according to Claim 1 wherein said first and second spring portions (14,15) are curved in opposite directions from each other. A contact according to Claim 1 wherein said first and second spring portions (14,15) are generally parallel to each other. A contact according to Claim 1 or Claim 3 wherein said first and second spring portions (14,15) are substantially the same in length. A contact according to Claim 1 or Claim 3 wherein said first and second spring portions (14,15) are of different lengths.

Inventors: MATSUOKA NORIYUKI, MATSUOKA, NORIYUKI
Applicants: YAMAICHI ELECTRONICS CO LTD, YAMAICHI ELECTRONICS CO., LTD.
Application year: 1992
Main classification: H01R13
IPC codes: H01R33, H01R13