JP2009272246A - Socket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a socket which responds to low resistance, having a larger current, and an increase in speed, and enables superior contact while utilizing advantages in both of a leaf spring type and an elastomer type. <P>SOLUTION: The socket 1 includes an insulating elastomer sheet 3 having a penetrating hole 3H, metal circuits 5A, 5B installed at least at a part of front and rear faces of this elastomer sheet 3, a convex part 7 installed at least at a part of the elastomer sheet 3 or the metal circuits 5A, 5B, and a through-hole 9 having a metal film formed on an inner wall of the penetrating hole 3H. Furthermore, a groove part 11 is installed around the convex part 7, and by sidewall parts of this groove part 11, a tapered part 13 is formed which is inclined so that an obtuse angle is formed against front and rear faces of the elastomer sheet 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a socket used when an IC package such as a CPU or LSI is mounted on a printed circuit board on a mother board side, and more particularly to a socket having a structure for forming a three-dimensional circuit using a three-dimensional circuit technique.

  Conventionally, techniques for mounting an IC package such as a CPU or LSI on a printed circuit board using a socket have been studied. Many personal computers and motherboards are equipped with sockets for mounting CPUs of LGA packages or BGA packages.

  In order to cope with the increase in the number of pins and the increase in speed that accompany improvements in functions and performance, CPUs are being increased in size and fine pitch. Along with this, the socket side has been increased in size and fine pitch.

  On the package side, it is expected that the amount of deflection, contact land, and ball variation will increase as the size increases. On the other hand, on the socket side, it is necessary to increase the allowable contact stroke in order to cope with an increase in the package size.

  Further, as a countermeasure to fine pitch, it is expected that the contact object will be miniaturized, but the structure must ensure a stroke necessary for stabilizing the contact resistance.

The current mainstream of LGA package sockets is 400 to 1000 pins with a pitch of about 1 mm, and a structure in which a metal plate is bent in a complicated manner to form a contact terminal of a predetermined shape, and the contact terminal is inserted into the socket housing. Is used. These conventional techniques are disclosed in Patent Document 1 and Patent Document 2, for example.
JP 2004-158430 A JP 2005-19284 A

  However, since the conventional technology disclosed in Patent Document 1 and Patent Document 2 uses a leaf spring method for contact terminals, if the spring is lengthened to increase the contact stroke, the contact terminal is brought into contact with an adjacent pin. There was a problem that the stroke could not be increased when the pitch was increased.

  In order to solve this problem, a method using a conductive elastomer has been studied. In this structure, since the repulsive force is determined by the characteristics of the elastomer, it is possible to ensure a sufficient stroke with the required load by selecting an elastomer having a repulsive force that meets the requirements.

  However, the problem of using a conductive elastomer is that the contact is not a metal but an elastomer, so that the contact resistance is higher than that of a metal contact, and there is a risk of heat generation and an increase in voltage drop when the current is increased. Furthermore, since the contact does not wipe the metal land when the package is inserted, a new problem arises that the oxide film cannot be removed from the land.

  It is an object of the present invention to provide a socket that can make good contact while responding to low resistance, large current, and high speed while taking advantage of both the leaf spring method and the elastomer method.

  In order to solve the above problems, a socket of the present invention includes an insulating elastomer sheet provided with a through hole, a metal circuit provided on at least a part of the front and back surfaces of the elastomer sheet, and the elastomer sheet or the metal. A socket having a convex portion provided in at least a part of the circuit and a through hole in which a metal film is formed on the inner wall of the through hole, and a groove portion is provided around the convex portion, and the side wall portion of the groove portion is The taper part which inclines so that an obtuse angle may be made with respect to the front and back of an elastomer sheet may be formed.

  In the socket of the present invention, it is preferable that in the socket, the elastomer sheet is made of a fluorine-based elastomer.

  In the socket of the present invention, it is preferable that in the socket, the elastomer sheet is formed by laminating elastomer layers on the front and back of a sheet-like core material made of a material having a smaller thermal expansion coefficient than that of the elastomer.

  As can be understood from the means for solving the problems as described above, according to the present invention, the contact terminal for connection to the printed circuit board and the IC package can be made of a metal circuit having good conductivity, and repulsion can be achieved. Since the force can be secured by the elastomer sheet, the load-stroke characteristic can be designed with the characteristic of the elastomer while being a contact by metal contact. Therefore, the contact resistance is low, the current can be increased and the speed can be increased, and the number of parts can be reduced.

  In addition, a groove is provided around the terminal of the convex portion, and the side wall portion of the groove is a tapered portion that is inclined so as to form an obtuse angle with respect to the front and back surfaces of the elastomer sheet.

(1) Since there is no blind spot portion of parallel light in the process of forming the metal circuit, it is not necessary to take measures such as inclining the elastomer sheet several times, and only one exposure is required.

(2) The part connected from the circuit upper surface to the side wall becomes an obtuse angle, and resist cutting due to resist flow in the PEB process can be prevented.

(3) In the development and etching processes, the blind spot of the spray solution disappears, and a new spray solution can be supplied at all times. Therefore, the dissolution of resist and plating and the removal by physical action can be promoted, and the production efficiency is improved. Contributes to quality improvement.

(4) The resistance to the lateral force vector with respect to the convex portion is increased, the circuit can be displaced vertically, and the designed function can be achieved.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2, a socket 1 according to this embodiment includes an insulating elastomer sheet 3 provided with a through hole 3H and a metal circuit provided on at least a part of the front and back surfaces of the elastomer sheet 3. 5A, 5B, a protrusion 7 provided on at least a part of the elastomer sheet 3 or the metal circuits 5A, 5B, and a through hole 9 in which a metal film is formed on the inner wall of the through hole 3H. Further, a groove portion 11 is provided around the convex portion 7, and a side wall portion of the groove portion 11 forms a tapered portion 13 that is inclined so as to form an obtuse angle with respect to the front and back surfaces of the elastomer sheet 3. To do.

  In this embodiment, the convex portion 7 is provided on at least a part of the elastomer sheet 3, and the convex portion 7 has a substantially semicircular dome shape. The metal circuits 5A and 5B are formed on the convex portion 7. Unlike the case of this example, as described above, the convex portion 7 is applied even when it is provided on at least a part of the metal circuits 5A and 5B.

  Further, the metal circuit 5 </ b> A on the front surface side of the elastomer sheet 3 and the metal circuit 5 </ b> B on the back surface side are electrically connected by the through hole 9. The metal circuits 5A and 5B are provided with a gold plating 15.

  Further, as shown in FIGS. 3 and 4, the socket 1 has good conductivity such as copper as a contact terminal for connection with the pattern wiring 17A of the printed circuit board 17 and the LGA 19A of the IC package 19. A metal foil made of a simple metal is used, and the repulsive force is secured by the elastomer sheet 3. By adopting this structure, it is possible to design the load-stroke characteristic with the characteristic of an elastomer while being a contact by metal contact.

  Therefore, since current flows through the metal circuits 5A and 5B in contact with the pattern wiring 17A of the printed circuit board 17 and the LGA land 19A of the IC package 19, the contact resistance is low, and the socket 1 corresponding to high current and high speed is provided. Become. Moreover, since the base material of the socket 1 and the elastomer for ensuring the repulsive force are integrated, the socket 1 with a small number of parts can be realized.

  The material of the elastomer sheet 3 can be appropriately selected from various insulating elastomer materials that can exhibit an appropriate elastic repulsion when a load is applied to the metal circuits 5A and 5B. In particular, it is preferable to use a fluorine-based elastomer. The reason for this is that when fluorine-based elastomers are used, the heat resistance becomes high, and when the socket 1 is joined to the printed circuit board 17 or the IC package 19, the solder can be reflowed, the joining process becomes easy, and the production is facilitated. This is because the cost can be reduced.

  The elastomer sheet 3 used as a base material or an elastic body generally has a large thermal expansion coefficient. When the CPU is mounted on the printed circuit board 17 via the socket 1, heat from the CPU is also transmitted to the socket 1. Therefore, when the elastomer sheet 3 is used as a base material, each terminal is considered in consideration of expansion and contraction of the elastomer. It is necessary to design the clearance.

  Moreover, the elastomer sheet 3 of this embodiment is configured by laminating an elastomer layer 3B on both front and back surfaces of a sheet-like core material 3A made of a material having a smaller thermal expansion coefficient than the elastomer material. The core material 3A reduces the heat generation of the CPU and the influence of heat in the manufacturing process. As the material having a small thermal expansion coefficient constituting the core material 3A, a material having a smaller thermal expansion coefficient than that of an elastomer such as glass fiber, glass epoxy resin, and polyimide, and a material close to the thermal expansion coefficient of the IC package 19 or the printed circuit board 17 is used. desirable. The elastomer sheet 3 is not limited to the above structure, and for example, the whole may be constituted by the elastomer layer 3B without using the core material 3A.

  Furthermore, the groove part 11 is provided in the ellipse shape by planar view along the periphery of the terminal formation area | region of at least one of the surface of the elastomer sheet 3, and a back surface. In other words, the groove portion 11 is provided around the convex portion 7. Thereby, in the state which applied the load, the transmission of the force by the tension | pulling of the elastomer produced between adjacent terminals and compression can be reduced. In addition, the said groove part 11 is not limited to elliptical shape by planar view, For example, it may be U-shaped by planar view around the convex part 7, or may be provided in another shape.

  Further, as shown in FIG. 2, even if a structure in which a large number of terminals including the metal circuit 5 and the through holes 9 are arranged, connection of all terminals can be ensured when a load is applied.

  Further, the socket 1 is controlled so that each terminal obtains a desired load-displacement characteristic by adjusting the dimensions of the groove portion 11 (groove depth, groove width, area surrounded by the groove, etc.). can do. Therefore, since various sockets having different load-displacement characteristics can be easily manufactured, it is possible to meet demands for various sockets having different load-displacement characteristics. Furthermore, when a load is applied to each terminal, the influence of the load on the adjacent terminals can be minimized. In addition, since current flows through the circuit forming portion, it is possible to realize low inductance by shortening the electrical conduction path, and to provide a socket 1 corresponding to low resistance, high current, and high speed. it can.

The groove 11 may be processed with a laser such as a YAG laser, a CO ₂ laser, an excimer laser, or a femtosecond laser after circuit formation is completed, or may be provided with a thin drill. Moreover, you may shape | mold the elastomer sheet 3 which provided the groove part 11 for reducing the transmission of the force by the tension | pulling of the elastomer which arises between adjacent terminals, and compression previously.

  This socket 1 is used when the terminal on the IC package 19 side is a land, or when the contact portion is exchanged during maintenance, like the server socket, so that the printed circuit board 17 side is not soldered and needs to be connected as a land. This is a socket structure for connecting, for example, an LGA package as the IC package 19 to be used and the printed board 17. By providing the convex part 7 in a part of the formation part of the metal circuits 5A and 5B, the structure is such that a stroke is generated depending on the height of the convex part 7.

  In addition, as a method of providing the convex portion 7 in a part of the metal circuit forming portion, the convex portion 7 is provided in advance on the elastomer sheet 3, and the through hole 3 </ b> H that becomes the convex portion 7, the metal circuit forming portion, and the through hole 9 It is also possible to perform a treatment such as plating. The convex part 7 formed on the elastomer sheet 3 can be easily formed by preparing a mold having a concave part provided with the convex part 7 at a desired position when the elastomer sheet 3 is formed.

  At this time, it is necessary to form a circuit on the surface of the elastomer sheet 3 including the convex portion 7. In this case, it becomes a problem whether an etching resist can be apply | coated to the surface including the convex part 7. FIG.

  In general, a spin coating method using centrifugal force and surface tension is used to form a thick resist film, but it is difficult to apply the spin coating method to apply a resist on a non-planar surface. That is, since the elastomer sheet 3 has a three-dimensional structure that causes a problem in one photolithography process of the manufacturing process, it is performed by film-type photoresist, spin coating, curtain coating, or printing that performs lamination using a general laminator. It is difficult to apply a liquid photoresist.

  Therefore, an electrodeposited positive photoresist (Kansai Paint Sonne EDUV-P800B) is used, but this resist needs to be heated by PEB (pre-exposure bake) after exposure, and softening and flow occur due to heating. For example, in the socket 21 as a comparative example as shown in FIG. 9, the resist is easily cut at the corners of the vertical wall surface 23.

  More specifically, the socket 21 of the comparative example is described for easy understanding of the characteristics of the socket 1 of this embodiment. The groove portion 11 is provided around the convex portion 25 and the side wall of the groove portion 11 is provided. The difference from the socket 1 of this embodiment is that the portion is a vertical wall surface 23. Others are the same as the socket 1.

  Further, in the case of the socket 21, in order to irradiate the UV light UV passing through the photomask 27 onto the vertical wall surface 23 during exposure, an inclination jig as shown in FIGS. It is necessary to tilt the elastomer sheet 3 using 29. When exposure is performed in this way, it becomes very difficult to control the boundary between the portion to which the UV light UV is to be applied and the portion that is not desired to be applied due to the influence of the tilting error of the elastomer sheet 3 and the warp of the elastomer sheet 3.

  Further, in the development and etching processes, the vertical wall surface 23 becomes a blind spot of the spray liquid, and the spray liquid does not directly hit. Therefore, it takes a long time to remove the resist and plating on the vertical wall surface 23.

  When the socket 21 is mounted on the mother board, if a load is applied perpendicularly to the terminals of the convex portion 25, the expected movement can be exhibited. However, the ideal vertical load is not always applied. Thus, when a load in an oblique direction is applied to the convex portion 25, the terminal of the convex portion 25 is inclined as shown in FIG. 13, and thus the function as designed cannot be exhibited.

  However, in the socket 1 of this embodiment, the groove portion 11 is provided around the convex portion 7, and the side wall portion of the groove portion 11 is inclined so as to form an obtuse angle with respect to the front and back surfaces of the elastomer sheet 3. Therefore, softening of the electrodeposited photoresist during PEB and resist cutting due to flow can be prevented. In addition, even when the ultraviolet light UV is irradiated vertically during exposure, the dead angle of the side wall portion is eliminated. Therefore, it is not necessary to incline the elastomer sheet 3 for exposure, and process management becomes easy. The socket 21 having the vertical wall surface 23 needs to be tilted according to each vertical wall surface 23 and therefore needs to be exposed several times to several tens of times. However, the socket 1 according to this embodiment performs one exposure. Productivity is improved.

  Further, in the development and etching processes, since the liquid directly hits the taper portion 13, a new liquid can be always supplied, and the removal of the resist and the plating by the physical action can be promoted. The time required can be shortened.

  Further, when the socket 1 is mounted, since the area of the lower part is larger than the upper part of the convex part 7, the resistance against the lateral force vector is increased. Therefore, as shown in FIG. 5, even if a load is applied to the convex portion 7 in an oblique direction, the terminal of the convex portion 7 is displaced vertically as shown in FIG. It is possible to fulfill the functions as designed.

  Next, the outline of the manufacturing method of the socket 1 of this embodiment will be described.

  In the elastomer molding die, a taper is provided at a portion corresponding to the taper portion 13 of the terminal side wall of the convex portion 7. A core material 3A made of a polyimide base material is set in the molding die, and an elastomer such as a fluorine-based elastomer is injected and cast to produce an elastomer base material. Next, a through hole 3H to be a through hole 9 is formed at a predetermined position on the sheet by a drill or a laser.

  Next, the elastomer is activated by performing a special pretreatment, and the electroless copper plating and the electrolytic copper plating are used together to form a metal film, for example, on the surface of the elastomer, the back surface, and the through hole 3H that becomes the through hole 9. Copper plating is applied. Note that a thick metal film can be applied to the elastomer sheet 3 by applying electroplating after applying a thin metal film by electroless plating in advance.

  Next, the oxide on the copper surface of the copper plating is removed with an acid-based pretreatment liquid, and an electrodeposition resist is applied. As a method of applying the electrodeposition resist, there is a method of spraying in the form of a mist by spray coating.

  A photomask is set on the electrodeposition resist using a jig. Next, the upper and lower surfaces of the electrodeposition resist are exposed, and PEB (Post Exposure Bake) is performed at 140 ° C. for about 15 minutes. Next, development is performed and etching is performed in a state where the resist of only the circuit portion is left, and the copper foil of only the circuit portion is left. In this state, the circuit is formed using an aqueous solution of iron chloride, copper chloride, ammonium hydroxide or the like to form a circuit. After that, surface finishing is performed by the gold plating 15.

  The socket 1 manufactured in the above manufacturing process is very fine with a pitch of 0.5 to 1 mm, but was able to show a load sufficient to stabilize the contact resistance.

  Further, since the area is increased by the tapered portion 13 extending from the upper portion toward the lower portion, the resistance against the lateral force vector applied to the terminal of the convex portion 7 is increased, and the terminal operation as designed can be performed. It was confirmed that wiping was performed on 19 lands and substrate lands.

  Next, the contact operation in the semiconductor device using the socket 1 of this embodiment will be described. As an example, a contact operation when the socket 1 is used as a socket for an IC of an IC package 19 such as an LGA package will be described.

  Referring to FIG. 3, socket 1 is placed on printed circuit board 17 of the semiconductor device, and IC package 19 (LGA package) is placed on socket 1. A pattern wiring 17A is formed on the printed circuit board 17, and an LGA land 19A is formed on the IC package 19. The socket 1 has a structure in which a stroke is generated depending on the height of the convex portion 7 provided in the metal circuit 5 portion.

  When a load is applied to the IC package 19, as shown in FIG. 6, the elastomer sheet 3 is compressed and sinks while generating a repulsive force, and the load at this time and the generated sink are the load − Displacement characteristics. Moreover, since the metal circuits 5A and 5B sink with the vicinity of the through hole 9 as a fulcrum, the contact point moves to the through hole 9 side when a load is applied. As a result, a wiping effect is brought about, and the oxide films on the respective metal contact surfaces can be removed to bring the fresh metal surfaces into contact with each other. Therefore, the contact can be realized with low resistance.

  In the socket 1 of the above-described embodiment, the convex portion 7 has a substantially semicircular cross section. However, other embodiments of the convex shape are shown in FIGS. As described above, the tip can be formed into an acute protrusion shape. Thereby, the wiping effect for removing the oxide on the metal surface can be further improved.

It is side surface sectional drawing which shows the socket of embodiment of this invention, and is sectional drawing of the arrow II line of FIG. It is a top view which shows the socket of embodiment of this invention. It is side surface sectional drawing which shows the state before giving pressing force with the semiconductor device with which the socket of FIG. 1 was mounted | worn. FIG. 4 is a side cross-sectional view showing a state when a pressing force is applied in the semiconductor device of FIG. 3. It is explanatory drawing of the state before an oblique load is applied to the terminal of the convex part of the socket of FIG. It is explanatory drawing of a state when a diagonal load is applied to the terminal of the convex part of the socket of FIG. It is side surface sectional drawing which shows the socket of other embodiment of this invention. It is side surface sectional drawing which shows the socket of other embodiment of this invention. It is side surface sectional drawing which shows the socket which has a vertical wall surface. It is state explanatory drawing which inclined the elastomer sheet using the jig | tool for inclination. It is state explanatory drawing which inclined the elastomer sheet to the opposite side to FIG. 10 using the jig | tool for inclination. It is explanatory drawing of the state before an oblique load is applied to the terminal of the convex part of the socket of FIG. It is explanatory drawing of a state when an oblique load is applied to the terminal of the convex part of the socket of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Socket 3 Elastomer sheet 3A Core material 3B Elastomer layer 5A, 5B Metal circuit 7 Convex part 9 Through hole 11 Groove part 13 Tapered part 15 Gold plating 17 Printed circuit board 17A Pattern wiring 19 IC package 19A LGA land 21 Socket 23 Vertical wall surface 25 Convex part 27 Photomask 29 Tilt jig

Claims (3)

  An insulating elastomer sheet provided with a through hole, a metal circuit provided on at least a part of the front and back surfaces of the elastomer sheet, a convex part provided on at least a part of the elastomer sheet or the metal circuit, and the through hole A socket having a through-hole formed with a metal film on the inner wall of the first and second grooves, and a groove portion is provided around the convex portion, and the side wall portion of the groove portion is inclined to form an obtuse angle with respect to the front and rear surfaces of the elastomer sheet. A socket having a tapered portion.   The socket according to claim 1, wherein the elastomer sheet is made of a fluorine-based elastomer.   3. The socket according to claim 1, wherein the elastomer sheet is formed by laminating elastomer layers on the front and back of a sheet-like core material made of a material having a smaller thermal expansion coefficient than that of the elastomer.

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