Contact and IC socket using the same

Abstract

To provide a contact which can be easily miniaturized and made high density, has high spring properties, can achieve stable electrical contact with either of two contact objects, and can be easily attached to an IC socket, and the IC socket using the same.SOLUTION: A contact is roughly "L-shaped" with one long side and the other short, and the tip of the long side protrudes from the exit of a contact accommodating portion that penetrates diagonally into the flat socket body and serves as the first contact point. An arc-shaped protruding portion of a bent portion of the "L-shape" contacts a corner portion that extends outward from the entrance of the contact accommodating portion of the socket body, and the tip of the short side connected to it protrudes from the socket body as the second contact point.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a contact and an IC socket using the same, and more particularly to a contact having two contact objects above and below, and an IC socket using such a contact. [Background technology]

[0002] Conventionally, contacts having two contact objects, one above the other (for example, the upper one is an IC package and the lower one is a printed wiring board), as disclosed in Patent Document 1, have been used as contacts for IC sockets for mounting and testing semiconductor packages (hereinafter referred to as "IC packages") Such contacts are configured to be able to electrically connect the IC package and the printed wiring board by elastically contacting both the IC package mounted in the IC socket and the printed wiring board such as a test board.

[0003] [Patent Document 1] JP 2008-21459 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] In recent years, with the trend toward narrower pitches for external contacts of IC packages and printed wiring boards mounted on IC sockets, there has been a demand for miniaturization of such contacts themselves. Therefore, in order to obtain a stable electrical connection between two contact objects, such as an IC package mounted in an IC socket and a printed wiring board, despite the miniaturization of the contacts, efforts have been made to increase the springiness of the contacts, as shown in Patent Document 1.

[0005] The object of the present invention is to improve the springiness of a contact and an IC socket using the same, even if the size of the contact is almost the same, and to increase the amount of elastic deformation of the contact part of the contact that electrically contacts the two external contacts of the contact object. More specifically, to make the bending stress uniform in the entire area of ​​the contact up to the elastic limit of the material. This makes it possible to prevent uneven electrical contact between the contact portion of the contact and the external contact, which occurs due to warping of the IC package or printed wiring board mounted on the IC socket. As a result, even if the IC package or printed wiring board that is the contact target is warped, the contact according to the present invention and the IC socket using the same can obtain a more stable electrical connection. [Means for solving the problem]

[0006] The contact is roughly "L-shaped" with one long side and the other short, and the tip of the long side protrudes from the exit of the contact accommodating section that penetrates diagonally into the flat socket body and serves as the first contact point. The arc-shaped protruding part of the bent part of the "L-shape" contacts the corner section that extends outward from the entrance of the contact accommodating section of the socket body, and the tip of the short side connected to this protrudes from the socket body as the second contact point.

[0007] The contact has the same configuration as above. The long piece is bent outwardly and inwardly from the base toward the tip at the middle, and extends substantially parallel to the base, with this bent portion being set slightly smaller than the distance between the wall surfaces of the contact receiving portion. When the first and second contacts come into contact with an object and the "L-shape" of the contact deforms deeply, the intermediate bent part of the long piece comes into contact with the wall of the contact accommodating portion and deforms in a direction that deepens the inclination of the tip arm, with this point as the fulcrum, and the short piece deforms in a direction that deepens the inclination of the tip side, with the corner contact part of the arc-shaped protrusion as the fulcrum. At this time, the central elastic deformation portion between the intermediate bent portion of the long piece and the corner contact portion of the arcuate protrusion deforms outward in an arc shape but is set so as not to abut against the wall surface of the contact receiving portion. Effect of the Invention

[0008] The actual usage state is as shown in Figure 5, where the first contact portion of the contact receives a force from the upper contact object, the second contact portion receives a force from the lower contact object, and the intermediate bent portion and arc-shaped protrusion of the long piece receive a force from the socket body, resulting in a balanced state. In order to make the theoretical concept of this structure easier to understand, the shape of the contact has been simplified by omitting the intermediate bent portion of the long piece and the arc-shaped protrusion, and the direction of the force is assumed to be vertical. The relationship of the forces received by the contacts, their deformation, and the displacement between the contacts are explained in Figures 1 and 2. Here, the first contact point at the tip of the long piece is represented by point A, the intermediate bent portion is represented by point B, the arc-shaped protrusion is represented by point C, and the second contact point at the tip of the short piece is represented by point D.

[0009] The relationship between the force and moment acting on the contact will be explained with reference to FIG. Points A and D are balanced by external forces, and this force is called P. Points B and C are balanced by forces from the socket body, and this force is called F. If the length of the arm part AB at the end of the long piece is S1, the length of the short piece CD is S2, and the length of the central elastic deformation part BC is 2L, then from the balance of the moment at point C, P(2L+S1)-2FL=PS2. Here, if S1 = S2 = S, then F = P. In other words, we can see that the forces applied to points ABCD are all the same P. Bending moment M at any point X on BC X =P(2L+Sx)-F(2L-x), but F=P, so M X =PS. The bending moment is smaller on AB and CD. In other words, the bending moment M on the central elastic deformation part BC X becomes constant at maximum.

[0010] Deformation of the contact is explained in Figure 2. To make the calculation easier, first determine the deformed shape when points B and C are regarded as rotation fulcrums (their positions do not move). The dashed line shows the original shape, the solid line shows the shape after deformation, and the two-dot chain line shows the positions of contact points A and D when only the central elastic deformation part BC is deformed. Since the bending moment is constant between BC, the center is horizontal. TIFF2025027921000002.tif13145 (Note that E is the modulus of elasticity of the contact material, and I is the second moment of area. TIFF2025027921000003.tif14170 is available.) TIFF2025027921000004.tif29170AB is assumed to be a uniform cross section) TIFF2025027921000005.tif14170This will be called equation ▲1▼. From this equation, the deformation of the central elastic deformation part BC where the bending moment is maximum and constant is TIFF2025027921000006.tif13170 (For example, 3x when L=S) Furthermore, C =i B Therefore, the total displacement of point D relative to point C is also δ DC = δ AB It is.

[0011] The bending stress acting on the contact will now be described. If the bending moment on the central elastic deformation part BC is constant and the cross section is uniform, that is, the plate thickness b and plate width c are constant, the bending stress at any point X between BC is given by the formula for material strength. TIFF2025027921000007.tif28170This shows a uniform deformation into an arc. TIFF2025027921000008.tif11128The bending stress on the central elastic deformation part BC is constant, so when force is applied, the entire area deforms uniformly in an arc shape and the bending stress increases by the same amount, and finally reaches the elastic limit point σ E (If it is any higher, it will start to permanently deform as a spring and will not return to its original shape.) This is the limit of use of the contact. In general, when force is applied to a structure, it will reach the elastic limit point σ E Even if it reaches this point, other parts still remain within that range and have some room for deformation, meaning that elastic deformation is not sufficient over the entire area. On the other hand, the fact that the central elastic deformation section BC of the section where the bending stress is constant is long means that the structure can accommodate a large amount of elastic deformation, and this is expressed by formula (1). As a supplementary note, in this embodiment, the bending moment of the tip arm AB and the short piece CD is smaller toward the tip, so the plate width is narrowed toward the tip so that the bending stress is constant. TIFF2025027921000009.tif13166 (The above formula is not accurate because the whole AC is inclined, but it does not affect the proof of the theoretical idea.)

[0012] In the contact according to the present invention, the bending stress is constant at a maximum over the entire area BC of the central elastic deformation portion, and as a result, it is possible to obtain a large amount of elastic displacement between the contact points. As a result, even if the IC package or printed wiring board to be contacted is warped, the contact according to the present invention and the IC socket using the same can obtain a more stable electrical connection. BEST MODE FOR CARRYING OUT THEINVENTION

[0013] A preferred embodiment of the present invention will now be described with reference to FIGS.

[0014] Fig. 3 is a perspective view of a contact according to one embodiment of the present invention, and Fig. 4 is a partial cross-sectional view showing a state in which the contact shown in Fig. 3 is mounted on a socket body of an IC socket and two contact objects are not attached. Fig. 5 is a partial cross-sectional view similar to Fig. 4 showing a state in which two contact objects are attached to an IC socket and the contact shown in Fig. 3 is in electrical contact with the two contact objects. Fig. 6 is a schematic exploded perspective view of an IC socket using a contact according to the present invention, and Fig. 7 is a schematic exploded cross-sectional view of the IC socket of Fig. 6. 8 and 9 are explanatory diagrams of a locking member that prevents the contact from slipping out of the socket body.

[0015] First, an IC socket using a contact having two contact objects according to the present invention will be described with reference to FIGS.

[0016] 6 and 7, IC socket 100 generally includes a socket body 20 and a pressing member 10. IC socket 100 is fixed to a printed wiring board 60 directly by fixing means 90 such as a screw, or to a base member 70 by penetrating printed wiring board 60.

[0017] The pressing member 10 presses the IC package 80 mounted on the IC socket 100 from above toward the contacts 40. In this embodiment, the lower surface of the pressing member 10 is formed as a pressing part for pressing the IC package 80. The pressing member 10 also preferably includes a heat sink 11 for dissipating heat, as shown in Figs. 6 and 7.

[0018] A plurality of contacts 40 are arranged on the socket body 20, which electrically connects the IC package 80 and the printed wiring board 60. The socket body 20 is made of an electrically insulating synthetic resin such as a liquid crystal polymer or polyethersulfone, and is a hexahedron having a roughly square shape when viewed from above. The outer periphery of the socket body 20 has a top surface 21, a bottom surface 23 parallel to the top surface 21, and four side surfaces that are perpendicular to the surfaces 21, 23 and connect the surfaces 21, 23 together.

[0019] An IC package mounting recess 22 having a bottom and a substantially square shape when viewed from above is formed in the approximate center of the upper surface 21 of the socket body 20. In this embodiment, the IC package mounting recess 22 has four side surfaces perpendicular to the upper surface 21 of the socket body 20 and a bottom surface 22a having a substantially rectangular horizontal cross section parallel to the upper surface 21 of the socket body 20. The bottom surface 22a constitutes a mounting surface for the IC package 80. Note that mounting members may be provided at the four corners or four sides of the bottom surface 22a having a substantially rectangular horizontal cross section to form the mounting surface for the IC package 80. Mounting holes 38 are formed at the four corners of the socket body 20 so as to penetrate the socket body 20, through which a fixing means 90 can pass when the socket body 20 is fixed to, for example, a printed wiring board 60.

[0020] In order to accurately maintain the horizontal positional relationship between the socket body 20 and the printed wiring board 60, the gap between the fixing means 90, the socket body mounting hole 38, and the mounting hole 39 of the printed wiring board may be minimized, or a projection and hole may be provided between the socket body 20 and the printed wiring board 60 separately to serve as a positional reference so as to prevent horizontal movement. This allows the socket body 20 and the printed wiring board 60 to move vertically. In order to accurately maintain the horizontal positional relationship between the IC package 80 and the IC package mounting recess 22 of the socket body 20, a spring (not shown) is inserted between the side walls of the two so that they come into contact with the walls that serve as references in the two horizontal directions. This allows the two to move vertically while being in close contact with the reference side walls.

[0021] A plurality of contact accommodating chambers 25, each accommodating a plurality of contacts 40, are arranged in a matrix on the bottom surface 22a of the IC package mounting recess 22 in correspondence with the contact pads 81 (FIG. 5) serving as external contacts of the IC package 80. As shown in FIG. 7, each of the contact accommodating chambers 25 accommodates one contact 40 facing in the same direction.

[0022] As shown in FIG. 4, the contact accommodating chamber 25 penetrates the socket body 20 from the bottom surface 22a of the IC package mounting recess 22 toward the bottom surface 23 of the socket body 20. As shown in FIG. The contact receiving chamber 25 preferably forms an angle of approximately 45° with the bottom surface 22a of the IC package mounting recess 22.

[0023] The structure of the contact receiving chamber 25 will be further described with reference to FIGS. The contact cavity 25 has a rectangular shape when viewed along the cross-sectional line AA shown in FIG. 4, and is therefore defined by four side walls. Of the four side walls, the side walls opposing each other on the left and right in FIG. The dimension W between the inclined surfaces of the first upper inclined side wall 29a and the second inclined side wall 31 is set to be slightly larger than the height H of the arc of the central elastic deformation portion BC, and the intermediate bent portion (T shown in FIG. 3 described later) of the long piece of the contact is set to be slightly smaller than W so that it can pass smoothly through the accommodating chamber. Since the dimension W between the inclined surfaces of the storage chambers can be small, if the thickness of the resin portion between adjacent storage chambers is also made thin, this structure is very suitable for achieving a narrow pitch.

[0024] A horizontal step 30 is provided between the first upper inclined side wall 29a and the first lower inclined side wall 29b. The horizontal step 30 is approximately parallel to the bottom surface 22a of the IC package mounting recess 22 or the bottom surface 23 of the socket body 20, and supports the arc-shaped protrusions 44 of the contacts 40 in the upward direction. Furthermore, when the central elastic deformation portion 43 connected to the arc-shaped protrusion 44 is in close contact with the second inclined side wall 31, if a small gap is set between the arc-shaped protrusion 44 and the downward inclined side wall 29b, the horizontal step portion 30 and the downward inclined side wall 29b will form a corner, which acts as a wall that prevents the arc-shaped protrusion 44 of the contact 40 from moving upward and to the left.

[0025] In Figure 4, the remaining two side walls, which are located at the front and back of the paper and face each other, are perpendicular to the first upper inclined side wall 29a and the first lower inclined side wall 29b, the second inclined side wall 31, and the bottom surface 22a of the IC package mounting recess 22.

[0026] By configuring the contact accommodating portion 25 in this manner, the first and second contact portions 41a, 45a of the contact 40 described later can be positioned to protrude upward and downward without interfering with the four side walls that define the contact accommodating chamber 25, as shown in FIG. 4. When the long piece tip 41a of the contact is pressed, the arcuate protruding portion 44 comes out from the corner, but the lower edge of the recess 51 of the locking member 50 prevents the contact protruding piece 47 from coming out. The structure of the locking member 50 will be explained later.

[0027] The contacts 40 are punched out of a thin conductive metal sheet such as beryllium copper (BeCu) into a long, thin strip of a predetermined shape, and then the strip is bent into a shape capable of contacting two contact objects, one above the other, as shown in FIG. 3.

[0028] In this embodiment, the contacts are shown in the embodiments of FIGS. 3 to 5, although the embodiments are not limited thereto.

[0029] The contact 40 according to this embodiment is generally dogleg shaped with one long piece and the other short, and the tip of the long piece forms the first contact 41a. The dogleg bent portion has an arc-shaped protrusion 44, and the tip of the short piece 45 connected to it has a second contact 45a. At the middle of the long piece, the tip side from the base part bends outward and then bends inward, extending almost parallel to the base part to form tip arm part 41. As described above, the height T of this intermediate bent part 42 is smaller than the dimension W between the inclined surfaces of contact accommodating space 25. The central elastic deformation part 43 between this intermediate bent part 42 and arc-shaped protruding part 44 has a uniform cross section.

[0030] It is preferable that the center of curvature G of the arc-shaped protrusion 44 also protrudes outward from the first upper inclined side wall 29a, and that the apex of the arc contacts the corner formed by the horizontal step 30 and the lower inclined side wall 29b. As a result, even if the contact 40 receives some force from below, the arcuate protrusion 44 and the corresponding corner are less likely to come out of engagement with each other.

[0031] The first contact portion 41a is formed at the tip of the long piece so as to be convex upward, and the second contact portion 45a is formed at the tip of the short side 45 so as to be convex downward in a circular arc shape. As shown in Figures 4 and 5, the first contact portion 41a can be displaced up and down and left and right, centered on the intermediate bend portion 42, and the second contact portion 45a can be displaced up and down and left and right, centered on the center of curvature G of the arc-shaped protrusion portion 44.

[0032] Next, the operation of contact 40 when IC socket 100 having contact 40 is mounted on printed wiring board 60 and then IC package 80 is attached will be described.

[0033] 5, the contact 40 is accommodated in the contact accommodating chamber 25 of the socket body 20, and then the contact 40 is prevented from coming out by the locking member 50, and the printed wiring board 60 and the IC package 80 are attached to the IC socket 100. At this time, the first contact portion 41a of the contact 40 abuts against the contact pad 81, which is the external contact of the IC package 80, and is elastically lowered by the IC package 80. Furthermore, the restoring force of the distal arm portion 41 and the central elastic deformation portion brings the first contact portion 41a into electrical contact with the contact pad 81 of the IC package 80 with a predetermined contact pressure.

[0034] At the same time, the second contact portion 45a of the contact 40 comes into contact with the contact pad 61, which is an external contact of the printed wiring board 60, and is pushed up by the printed wiring board 60. The short piece portion 45 rotates around the center of curvature G of the arc-shaped protrusion 44 and elastically deforms, causing the second contact portion 45a to elastically rise. In addition, the return force of the short piece portion 45 electrically contacts the second contact portion 45a and the contact pad 61 of the printed wiring board 60 with a predetermined contact pressure. For the sake of explanation, it has been described above that the first arm portion 41, the central elastic deformation portion 43, and the short piece portion 45 move individually, but as explained in FIGS. 1 and 2, they elastically deform while the overall force is balanced.

[0035] At this time, the vertical forces acting on the contact 40 are balanced as shown in Fig. 1. That is, the arcuate protrusion 44 is supported in the vertical direction so as to be in contact with the first horizontal step 30.

[0036] The first contact portion 41a is displaced up and down and left and right around the intermediate bent portion 42, while the second contact portion 45a is displaced up and down and left and right so as to draw a circle around the center of curvature G of the arc-shaped protruding portion 44. As a result, both the first contact portion 41a and the second contact portion 45a also move to the right, but since the IC package 80, the socket body 20, and the printed wiring board 60 approach each other vertically while accurately maintaining their horizontal positional relationship, frictional forces are applied to the left from the contact pads 81 of the IC package 80 and the contact pads 61 of the printed wiring board 60. Therefore, the contacts 40 are supported horizontally as the arc-shaped protrusions 44 abut against the first downwardly inclined side wall 29b. In summary, the contact 40 is stably held within the contact receiving portion 25 while the arcuate protruding portion 44 abuts against the corner formed by the first horizontal step portion 30 and the downward inclined side wall 29b.

[0037] The structure of the locking member 50 will be described with reference to Figures 8 and 9. Figure 8 is a side view of Figure 4, showing that the locking member 50 is fitted into the groove 28 provided on the underside of the socket body 20 and fixed thereto. Figure 9 shows the state just before the contact is inserted into the socket body and the locking member is pushed into the corresponding position (Figure 4 shows the state after it has been pushed in and fixed). The groove 28 is connected to the contact receiving chamber 25 so that the retaining projection 47 projects into the groove 28 when the contact is received in the receiving chamber. The locking member 50 is provided with a recess 51 whose edge surrounds the contact retaining projection 47. The distance M between the contact retaining projections 47 is greater than the distance N between the walls of the accommodation chamber, and it can be seen that the lower edge of the recess 51 prevents the contact from slipping out downward (see also FIG. 4). The depth of the recess 51 is set so that the contact retaining projection 47 does not come into contact with it. (The recess 51 may be connected on both sides and penetrate through the recess.) Accurate positioning of the socket body 20 and the locking member 50 is achieved by a combination such as the projection 52 and the recess 26 in FIG. The socket body 20 and the locking member 50 are press-fitted into the groove 28 at an appropriate interval and firmly fixed.

[0038] There is a slightly large space between the edge of the recess 51 of the locking member 50 and the contact anti-slip protrusion 47 to allow movement when the contact is deformed, but as described above, when contact is made, the contact 40 is stably held within the contact accommodating portion 25 as the arc-shaped protrusion 44 abuts against the corner formed by the first horizontal step portion 30 and the downward inclined side wall 29b, so this does not cause a problem. [Brief description of the drawings]

[0039] [Figure 1] This is the relationship between the force and moment acting on the contact. [Diagram 2] This is a deformation of the contact. [Diagram 3] FIG. 2 is a perspective view of a contact according to one embodiment of the present invention. [Figure 4] 4 is a partial cross-sectional view showing a state in which the contact shown in FIG. 3 is mounted on a socket body of an IC socket, but two contact objects are not attached. FIG. [Diagram 5] 5 is a partial cross-sectional view similar to FIG. 4, illustrating a state in which two contact objects are attached to an IC socket and the contact shown in FIG. 3 is in electrical contact with the two contact objects. [Figure 6] 1 is a schematic exploded perspective view of an IC socket using a contact according to the present invention. [Figure 7] 7 is a schematic exploded cross-sectional view of the IC socket of FIG. 6. [Figure 8] FIG. 9 is an explanatory diagram of a locking member that prevents the contact from coming off the socket body. [Explanation of symbols]

[0040] 20 Socket body 25 Contact receiving portion 29a first upper inclined side wall 29b first lower inclined side wall 30 horizontal step portion 31 second upper inclined side wall 40 Contact 41 End arm 42 Intermediate bent portion 42a First contact portion 43 central elastic deformation portion 44 arc-shaped protrusion portion 45 Short piece 45a Second contact part 50 Locking member 60 Printed wiring board 80 IC package 100 IC Sockets G Center of curvature of arc-shaped protrusion

Claims

1. The contact is roughly "L-shaped" with one long side and the other short, and the tip of the long side protrudes from the exit of the contact accommodating section that penetrates diagonally into the flat socket body and serves as the first contact point. The arc-shaped protruding part of the bent part of the "L-shape" contacts the corner section that extends outward from the entrance of the contact accommodating section of the socket body, and the tip of the short side connected to this protrudes from the socket body as the second contact point.

2. A contact having the same configuration as claim 1, The long piece is bent outwardly and inwardly from the base toward the tip at the middle, and extends substantially parallel to the base, with this bent portion being set slightly smaller than the distance between the wall surfaces of the contact receiving portion. When the first and second contacts come into contact with an object and the "L-shape" of the contact deforms deeply, the intermediate bent portion of the long piece comes into contact with the wall of the contact accommodating portion, and the tip side deforms in a direction deepening the inclination, with this point as the fulcrum, while the short piece deforms in a direction deepening the inclination, with the corner contact portion of the arc-shaped protrusion as the fulcrum. At this time, the area between the intermediate bent portion of the long piece and the corner contact portion of the arcuate protrusion is deformed outwardly in an arcuate shape, but is set so as not to come into contact with the wall surface of the contact receiving portion.

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