JP4749359B2 - Contact and socket for integrated circuit using the same - Google Patents

Description

  The present invention relates to a contact and a socket for an integrated circuit using the contact, and more particularly, to a contact shape suitable for a test socket used in an area array type (for example, BGA type) IC package having a spherical bump.

  Conventionally, sockets disclosed in Patent Literature 1 and Patent Literature 2 are known as sockets used in integrated circuits (ICs).

  Patent Document 2 discloses that a contact pin used for an IC socket includes a contact portion, an elastic body portion that allows the contact portion to be displaced in a vertical direction within a predetermined range, and a portion that is inserted and fixed in a socket base. Although configured, this contact had the following problems.

  That is, first, since the contact with each spherical bump of the IC package is only one point on the bottom surface of the bump, the bottom surface of the bump is likely to be damaged. For this reason, there is a lack of stability in terms of contact reliability of electrical connection as compared with a contact having multiple contacts with each bump.

  Second, as shown in FIG. 1, since the continuous portion of the contact portion 102 of the contact and the C-shaped elastic body portion 104 has a straight vertical shape, the pressing force is applied to the contact portion of the contact when the IC package is pressed. From 102, the C-shaped elastic body portion 104 is added in the vertical direction as it is. At this time, since only the C-shaped elastic body portion 104 of the contact is flattened, the contact portion 102 (free end) of the contact is displaced as indicated by an arrow 106 and is displaced in the vertical direction (Z) and in the planar direction ( XY). As a result, the contact portion 102 of the contact held in the alignment hole of the platform (not shown) strongly contacts the inner peripheral surface of the alignment hole. As a result, the contact force of the bump of the contact is reduced, resulting in contact reliability. It also contributes to variation.

  The above phenomenon is not a problem when the spring design of the contact can be performed with a sufficient margin as in the conventional case. However, the lightness, thinness, and miniaturization have progressed as in recent years, compared to the required load (in this case, the predetermined contact force). This was a particular problem when the material had to be used in a state close to the material strength limit.

As disclosed in Patent Document 1, as shown in FIG. 2, the contact pin used for the IC socket is at least a contact portion 210 and an elastic body that can displace the contact portion 210 in the vertical direction within a predetermined range. 220, and the contact portion 210 has a relief portion that is in non-contact with the bottom dead center portion 202 in the lower spherical surface of the spherical bump 200 of the IC package, and around this relief portion. 1 has a flat contact surface 212 that comes into pressure contact with the spherical surface outside the bottom dead center 202. The contact makes contact with the bumps of the IC package at many points, and the first problem of the contact has been solved, but has the following problems.

  First, since the central portion of the contact is deformed by the operation plate, the contact portion 210 (free end) of the contact is originally a mechanism that contacts the alignment hole of the platform. The power was easy to vary. Second, it is assumed that the contact with the IC package bump 200 is in surface contact with the contact flat portion 212, and it is not considered that the concentrated load is applied. Third, it does not have a function of wiping the bump surface.

For the above reasons, there are cases where the contact reliability of electrical signal connection is insufficient (unstable) depending on the use environment and use conditions, and further improvements and improvements have been demanded. This requirement has become an urgent problem with the demand for higher density of passive components.
JP-A-6-203926 JP 7-505255 A

  In recent years, along with the downsizing and higher functionality of electrical devices equipped with ICs, the type of IC package has metal balls or metal bumps on the base surface of the package body at regular intervals so that it can be surface-mounted on a printed wiring board. The area array type in which the external terminals are arranged in a grid pattern has become the mainstream, and at the same time, these IC packages have been downsized and the bump arrangement interval (pitch) has been narrowed. Correspondingly, IC sockets have been required to reduce the size of the socket body and to reduce the contact pitch.

  In response to these requirements, conventional area array type IC socket contacts have the above-mentioned quality problems (particularly, the decrease in the contact force of IC bumps due to contact with other members). As a result, improvement of the contact shape has been demanded from the viewpoint of ensuring the contact reliability of the electrical connection of the used contacts.

  Accordingly, a first technical problem to be solved by the present invention is to provide a contact for an area array type IC socket, which provides a reduced contact while ensuring sufficient electrical connection contact reliability. is there. A second technical problem to be solved by the present invention is to provide a contact capable of easily assembling and arranging the contact in the socket. Furthermore, a third technical problem to be solved by the present invention is to provide an IC socket that can use such a contact, and thereby can cope with a higher density of bumps of an area array type IC package. is there.

  In order to solve the above technical problem, the present invention provides a contact having the following configuration.

  The contact of the present invention includes an upper end contact portion that contacts the bumps of the IC package, a lower end terminal portion that is electrically connected to the circuit board and has a base end fixed to the integrated circuit socket, the upper end contact portion, And an elastic body portion including one curved portion that is substantially C-shaped projecting laterally between the lower end terminal portion and the upper end contact portion is elastically displaced in the vertical direction by the elastic body portion. It is of a type configured to be able to. The upper end elastic body portion has a substantially C-shape other than the one curved portion and protrudes to the side of the upper end contact portion side and / or the lower end terminal portion side substantially opposite to the one curved portion. It has a curved part.

  In the above configuration, when the upper end terminal portion is pushed by the bump of the IC package, a downward load is applied to the curved portion of the elastic body portion. As a result, the curved portion of the elastic body portion is flattened to generate a spring force. When the magnitude of the spring force and the magnitude of the load coincide with each other, the contact maintains an equilibrium position.

In general, as shown in FIG. 9, according to material mechanics, in a uniform curved beam OP ₁ P ₂ , one end O (fixed end) is the origin, and the tangent and normal at point O are the x-axis. , Y-axis, and when a load W is applied in the downward direction of the y-axis at the free end P ₂ of the curved beam, the displacements Δx and Δy in the x and y directions of the free end P ₂ are expressed by the following equations: Given in.

Here, E is the modulus of longitudinal elasticity, I is sectional secondary coefficient, r is the radius of curvature of the curved beam, alpha is a central angle formed between the arbitrary point P and the free end P ₂ of the curved beam.

  Each of the approximately C-shaped curved portions of the elastic body portion is not limited to a uniform curved beam as assumed when the above formula is derived. Generally, however, when a downward load is applied to the upper end of the elastic body portion, While flattening and shrinking Δy, Δx projects sideways with respect to the lower end thereof, that is, on the side opposite to the curved projecting side.

In the above configuration, the elastic body portion has a plurality of bending portions, and the other bending portion protrudes on the opposite side to the protruding direction of one bending portion, so when a downward load acts on the elastic body portion from the contact portion, Each curved portion is flattened. For example, in the case of having another bending portion protruding to the side opposite to the one bending portion on the contact portion side of one bending portion, as shown in FIG. The upper end is flattened in the vertical direction with respect to the lower end to contract Δy _{2 and} protrudes Δx ₂ laterally with respect to the lower end. As for the other curved portions, the upper end thereof is contracted by Δy _{1 in the} vertical direction with respect to the lower end, and Δx ₁ protrudes laterally with respect to the lower end. At this time, the protruding directions to the sides of the curved portions are opposite to each other. Therefore, on the whole the elastic part, the vertical displacement △ y ₁ + △ y _2, and the displacement of the lateral △ x ₂ - a △ x _1. By appropriately configuring the respective curved portions of the elastic body portion, if Δx ₂ −Δx ₁ ≈0, as shown in FIG. 10 (II), the elastic body portion is generally displaced only in the vertical direction. If it does in this way, the contact part of a contact pin will not contact strongly with the alignment hole of a platform, and the contact failure of a contact part can be avoided as a result.

  Therefore, the area array type IC socket contact can be reduced in size while ensuring sufficient contact reliability of electrical connection.

  Preferably, the elastic body portion protrudes on the side of the upper end contact portion and the lower end terminal portion of the one bending portion on the side opposite to the one bending portion, and has a curvature from the one bending portion. Each of the other curved portions having a substantially C-shape having a curvature with a small radius is provided.

  According to the above configuration, the two curved portions having a small radius of curvature mainly cancel the lateral displacement of one curved portion. The vertical displacement of the elastic body portion is mainly given by one curved portion. Therefore, the elastic body portion is elastically deformed stably with a small and simple configuration.

  The present invention also provides other contacts.

  The contact of the present invention includes an upper end contact portion that contacts the bumps of the IC package, a lower end terminal portion that is electrically connected to the circuit board and has a base end fixed to the integrated circuit socket, the upper end contact portion, And an elastic body portion including one curved portion of a substantially C shape projecting laterally between the lower end terminal portion, and the upper end contact portion is elastically displaced in the vertical direction by the elastic body portion. It is of a type configured to be able to. The upper end contact portion has two contact pieces that protrude upward in parallel with each other. Each of the contact pieces has a tapered shape in which each upper end side is inclined in a direction approaching each other and becomes narrower as it goes upward, and has an upper end portion that is round and curved.

  In the above configuration, when the upper end contact portion of the contact pin is inserted into the alignment hole of the platform, the tip is tapered so that the insertion becomes easy. Therefore, the contacts can be easily assembled and arranged in the IC socket.

  Further, in the above configuration, the bump of the IC package contacts the upper end of each contact piece at the upper end contact portion of the contact pin, spreads between the upper end portions of the contact piece, and contacts while wiping the upper end portion of the contact piece. To do. Since the contact pieces are close to each other at the upper end side and have a letter C shape, the curved upper end portion of the contact piece and the bump are always in a point contact state even when the contact piece is pushed and widened between the upper end portions. Become. Therefore, sufficient contact reliability of electrical connection can be ensured even if the size is reduced.

  The present invention also provides an integrated circuit socket.

  The socket for an integrated circuit of the present invention is electrically connected to the base, a platform for supporting the integrated circuit, the integrated circuit, and has a space for the base to support the platform. A contact type that allows elastic movement of the platform; and means for holding the platform relative to the base at a stationary position and means for allowing parallel movement of the platform from the stationary position toward the base. Is. The contact is a contact having any one of the configurations of the present invention described above.

  According to the above configuration, it is possible to cope with the increase in density of area array type IC bumps by using contacts having high contact reliability with the bumps of the integrated circuit.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings.

  First, the contact 50 of the first embodiment and the test IC socket 1 using the contact 50 will be described.

  As shown in the perspective view of FIG. 3 and the side view of FIG. 4, the contact 50 generally includes a contact portion 52, an elastic body portion 62, a fixing portion 72, and a terminal portion 82, from the upper end toward the lower end. Prepare. The contact 50 is made of an electrically conductive elastic metal material capable of transmitting an electrical signal. For example, in the area array type IC socket 1 shown in the perspective view of FIG. 7 and the cross-sectional view of FIG. It is particularly preferably used as a conductive connection element that contacts and separates the bumps of the package.

  As shown in the enlarged perspective view of FIG. 5, the contact portion 52 of the contact 50 includes a base end 54 and a pair of contact pieces 56. The lower portions of the pair of contact pieces 56 are respectively connected to both sides of the base end 54 and extend substantially parallel to each other in the vertical direction. The upper portions of the pair of contact pieces 56 protrude upward, face toward the inner center as they go upward from the bottom, approach each other, incline in a mountain shape, that is, in a substantially C shape, and have a tapered shape. The upper end portion 58 of each contact piece 56 is processed with roundness, and as will be described in detail later, as shown in the explanatory view of FIG. 6, the upper end portion 58 is opened by contact with the spherical bump 90 of the IC package. Even if it is lost, it is always in point contact. The interval W1 of the upper end portion 58 of the contact piece 56 and the length L of the upper portion of the contact piece 56 corresponding to a substantially cantilever are determined in consideration of the sliding action of the surface of the bump 90 of the IC package.

  The elastic body portion 62 allows the contact portion 52 to be elastically displaced in the vertical direction. That is, as shown in FIGS. 3 and 4, the elastic body portion 62 includes a substantially C-shaped main bending portion 66, an upper connecting portion 64 that connects the contact portion 52 and the main bending portion 66, and a main bending portion. The lower connection part 68 which connects between the part 66 and the fixing | fixed part 72 is provided. Each of the connecting portions 64 and 68 has substantially the same curved shape having a substantially C shape. Each connecting portion 64, 68 is curved to the opposite side of the main curved portion 66, and the radius of curvature of each connecting portion 64, 68 is smaller than the radius of curvature of the main curved portion 66.

  When a load in the vertical direction acts on the elastic body portion 62 due to contact with the bumps of the IC package, the main curved portion 66 corresponding to the bending beam and the connecting portions 64 and 68 are respectively in the vertical direction and the horizontal direction as described above. It is displaced to. Since the main bending portion 66 and the connecting portions 64 and 68 are displaced in the horizontal direction in the direction opposite to the respective curved protruding directions, the horizontal displacement of the main bending portion 66 is caused by the horizontal displacement of the connecting portions 64 and 68. Accordingly, the contact portion 52 can be dimensional accuracy required by the IC socket design standard (for example, EIAJ EDR-7315) before using the IC socket (before applying stress), when using (when applying stress). ) Can be maintained.

  The fixing portion 72 includes a reference wall 74 that fixes the contact 50 to the base 10 and a pair of side walls 76. The side wall 76 has a locking projection 78 at its lower end.

  When the contact 50 is assembled in the IC socket 1, the terminal portion 82 protrudes downward from the socket 1 and is fixedly connected to a conductor of an external circuit board such as a printed wiring board (not shown). It has become.

  Next, the IC socket 1 using the contact 50 having the above configuration will be described.

  As shown in FIGS. 7 and 8, the IC socket 1 generally includes a base 10, a platform 20 that supports the IC package, and a cover 40 that holds the IC package that is in contact with the platform 20 (not shown in FIG. 7). ), An alignment plate 30 disposed on the lower side of the base 10, and a plurality of contacts 50 (only one part is shown).

  The base 10 has a substantially rectangular plate-like bottom wall 12 and four side walls 16 a, 16 b, 16 c, 16 d that protrude upward from the four sides of the bottom wall 12. An opening space 18 is formed. The elastic body portion 62 of the contact 50 is arranged in the internal opening space 18. Through holes 14 (only a part of which is shown) are formed in the bottom wall 12 corresponding to the arrangement of bumps of the IC package. The through hole 14 is slightly shifted in the center position in the vertical direction, and an upward and downward step surface is formed at an intermediate position of the bottom wall 12.

  The platform 20 has a substantially rectangular plate shape, and includes raised ridges 22 raised at the four corners of the upper surface thereof to form a mounting portion, that is, a nest, for an IC package. In the platform 20, through holes 24, that is, alignment holes are formed corresponding to the bump arrangement of the IC package. The platform 20 is positioned within a predetermined horizontal gap by the upper part of the side walls 16a, 16b, 16c, 16d of the base 10, and the upper limit position is regulated by the nest bracket 28 fixed to the upper part of the side walls 16b, 16d of the base 10. In this state, the contact 50 is elastically supported upward by the contact 50 and is in a state of floating from the base 10.

  The alignment plate 30 has a generally rectangular plate shape, and four locking legs 32 projecting upward are provided around the alignment plate 30 so as to be detachably held on the lower side of the base 10. . Specifically, the locking leg 32 has a protrusion 33 at its tip, and the locking leg 32 is inserted from below into a recess 17 formed in the side walls 16 b and 16 d of the base 10. The protrusion 33 of the locking leg 32 engages with the upper surface of the bottom wall 12 of the base 10 so that the alignment plate 30 does not move downward from the bottom wall 12 of the base 10 by a certain amount or more. A through hole 34 is formed in the alignment plate 30 corresponding to the through hole 14 of the base 10.

  The cover 40 is rotatably attached to the base 10 by a hinge arranged along one side of the base 10, that is, one side wall 16a. The cover 40 has a latch 42 that engages with the protrusion 19 provided on the side surface 16c facing the one side wall 16a, and can hold the cover 40 in a closed state.

  The contact 50 is held by the base 10 by inserting the terminal portion 82 side of the contact 50 into the through hole 14 of the bottom wall 12 of the base 10 from above. At this time, the fixing portion 72 of the contact 50 has the lower end surface of the reference wall 74 abutting on the upward step surface of the through hole 14 in the bottom wall 12 of the base 10, and the protrusion 78 of the side wall 76 is formed in the through hole 14. The base 10 is fixed to the bottom wall 12 by being locked to the upward stepped surface. By fixing in this way, the contact 50 can be fixed without applying excessive stress to the bottom wall 12 of the base 10, so that unlike the case of the conventional press-fitting method, the deformation of the contact 50 during assembly or Generation | occurrence | production of defects, such as whitening and a crack of the base 10, can be prevented markedly.

  The terminal portion 82 of the contact 50 protrudes downward through the through hole 34 of the alignment plate 30. The protruding tip 84 of the terminal portion 82 is electrically connected to, for example, a hole of a circuit board (not shown) to which the IC socket 10 is attached.

  After all the contacts 50 are supported by the base 10, the platform 20 is placed on the base 10. At this time, since the upper end side of the contact portion 52 of each contact 50 is narrowed, each contact portion 52 of the corresponding contact 50 can be easily inserted into each through hole 24 of the platform 20. The contact 50 supports the platform 20 so that the platform 20 can be displaced in the vertical direction by the contact portions 52 being in sliding contact with the through holes 24 of the platform 20. At this time, the tip end side of the contact piece 56 of each contact portion 52 of the contact 50 protrudes from the upper surface of the platform 20.

  When the IC socket 1 having the above configuration is used, the IC package (not shown) is placed on the platform 20 and then the cover 40 is closed, and each bump of the IC package and an external circuit (not shown) are electrically connected by the contact 50. Connecting.

  When the cover 40 is closed, contact between the cover 40 and the IC package does not occur simultaneously across the entire surface of the IC package, but rather is concentrated along one end of the IC package. The platform 20 of the IC socket 1 is supported by the contact 50 so as to be elastically displaceable in the vertical direction with respect to the base 10, and the platform 20 is positioned with respect to the base 10 with a horizontal gap. The IC package is freely tilted in an arbitrary direction according to the force applied nonuniformly to the IC package to prevent damage to the IC package. When the cover 40 is completely closed, the platform 20 is substantially completely parallel to the cover 16. In this final position, the force applied to the IC package by the cover 40 is distributed almost evenly on the surface of the IC package, and the good contact between the bumps of the IC package and the contact portion 52 of the contact 50 is as follows. It becomes a state.

That is, as shown in FIG. 6, due to the force applied to the IC package, the spherical lower surface of the bump 90 comes into contact with the upper end portions 58 of the pair of contact pieces 56 of the corresponding contact 50 and pushes between the upper end portions 58. . For example, the distance between the upper end portions 58 of the pair of contact pieces 56 becomes the width W ₂ that is opened by contacting the bump 90 from the minimum width W ₁ when not in contact with the bump 90. When the bump 90 pushes open the upper end portion 58 of the pair of contact pieces 56, the surface of the bump 90 is wiped to remove the oxide film, and the wiping portion has a convex shape with the upper end portion 58 rounded. Since the portions are in contact, good contact can be obtained between the bump 90 and the contact 50.

  Further, since the upper end sides of the pair of contact pieces 56 are tapered (inwardly opened) in a mountain shape (substantially C-shaped), even if the upper end portions 58 of the pair of contact pieces 56 abut against the bumps 90 and open, 90 is always in contact with the convex rounded portion of the upper end 58. If the contact piece is inclined in an approximately V shape (opened outward), if the contact piece hits the bump and opens, the flat part inside the contact piece comes into contact with the bump. It is not a contact condition. In the case where the contacts are outwardly opened, problems such as difficulty in inserting the contacts into the alignment holes 24 of the platform 20 occur during assembly.

  The upper end portion 58 of the contact piece 56 is specifically designed in shape and structure in consideration of the size and height of the bump, and is designed to obtain good contact with the bump 90. As a good example of the bump 90 and the contact portion 52 of the contact 50, it is preferable that the perpendicular formed to the tangent line at the two contact points, that is, the angle β formed by the normal line is 60 ° to 120 °. If the angle β is too small, the lowermost surface of the bump 90 is damaged, and dents and damages are likely to occur. On the other hand, if the angle β is too large, the contact 50 is likely to hit the bump 90 unless the socket, IC package, and both are arranged with high precision during manufacture and assembly.

  Next, second and third embodiments in which the upper end shape of the contacts is different from the first embodiment will be described.

  As shown in the enlarged perspective view of FIG. 11, the contact according to the second embodiment forms an upper end portion 58a by rounding the upper end side of each contact piece 56a of the contact portion inward in an arc shape. Therefore, even if the contact with the bump is repeated, the upper end portion 58a of the contact piece 56a is hardly deformed or worn.

  As shown in the enlarged perspective view of FIG. 12, the contact according to the third embodiment has a raised portion 59 provided around the portion in contact with the bump at the upper end portion 58 b of the contact piece 56 b of the contact portion. The bump 59 always contacts the center of the upper end portion 58b of the contact piece 56b by the raised portion 59.

  In addition, this invention is not limited to said each embodiment, It can implement in another various aspect.

It is a principal part perspective view of the contact of a prior art example. It is a principal part perspective view of the contact of another prior art example. It is a perspective view of the contact of 1st Embodiment of this invention. FIG. 4 is a side view of the contact of FIG. 3. It is an expansion perspective view of the contact part of the contact of FIG. It is explanatory drawing of the contact of a contact. FIG. 4 is an exploded perspective view of an IC socket using the contact of FIG. 3. It is sectional drawing of the IC socket of FIG. It is explanatory drawing of the elastic deformation | transformation of a contact. It is explanatory drawing of the elastic deformation | transformation of a contact. It is an expansion perspective view of the contact part of the contact of 2nd Embodiment of this invention. It is an expansion perspective view of the contact part of the contact of 3rd Embodiment of this invention.

Explanation of symbols

1: IC socket, 10: base, 12: bottom wall, 14: through hole, 16a, 16b, 16c, 16d: side wall, 17: recessed, 18: internal opening space, 19: protrusion, 20: platform, 22: protuberance Part, 24: through hole, 28: nest bracket, 30: alignment plate, 32: locking leg, 33: protrusion, 34: through hole, 40: cover, 42: latch, 50: contact, 52: contact part (upper end Contact portion), 54: proximal end, 56, 56a, 56b: contact piece, 58, 58a, 58b: upper end portion, 59: raised portion, 62: elastic body portion, 64: upper connecting portion (other curved portion), 66: main curved portion (one curved portion), 68: lower connecting portion (other curved portion), 72: fixed portion (lower end terminal portion, proximal end) 74: reference wall, 76: side wall, 78: protrusion, 82 : Terminal part (lower end terminal part), 84: tip, 90: Amplifier.

Claims (2)

An upper end contact portion (52) that contacts the bumps of the IC package, a lower end terminal portion (72, 82) that is electrically connected to the circuit board and whose base end (72) is fixed to the integrated circuit socket; Between the upper end contact portion (52) and the lower end terminal portion (72, 82), there is provided an elastic body portion (62) including one curved portion (66) having a substantially C-shape projecting laterally. In the contact (50), the upper end contact portion (52) can be elastically displaced in the vertical direction by the elastic body portion (62). There are two contact pieces (56, 56a, 56b) that protrude upward substantially parallel to each other, and each contact piece (56, 56a, 56b) is inclined upward in a direction in which each upper end side approaches each other. The taper shape is narrower and the IC package Characterized in that it has an upper end surface which is convexly curved round and toward the other contact piece over di bump contacts (58a, 58b), respectively, contact.   A base (10), a platform (20) for supporting an integrated circuit, and an electrical connection to the integrated circuit, and a space (18) for the base (10) are provided to support the platform (20). And a contact (50) allowing the platform (20) to move elastically relative to the base (10), and holding the platform (20) relative to the base (10) in a stationary position, Means for allowing the platform (20) to translate in the direction from the base (10) to the base (10), wherein the contact (50) is a contact according to claim 1. A socket for integrated circuits.

Images