Method of manufacturing spring contact pin using precipitation hardening process

Abstract

The method of manufacturing a spring contact pin using a precipitation hardening process according to exemplary embodiments of the present invention may comprise the steps of: manufacturing a plurality of contact pins made of a copper alloy; performing a first heat treatment process for hardening the plurality of contact pins; performing an electroless nickel plating process by using, as plating substrates, the plurality of contact pins that have undergone the first heat treatment, thereby forming a nickel plating layer; performing a second heat treatment process for precipitation hardening of the nickel plating layer; and coupling two contact pins among the plurality of contact pins as an upper contact pin and a lower contact pin, respectively, and interposing a spring between the upper contact pin and the lower contact pin, thereby manufacturing a spring contact pin.

Description

Method for manufacturing spring contact pins using a precipitation hardening process

[0001] The present invention relates to a method for manufacturing a spring contact pin using a precipitation hardening process, and more specifically, to a method for manufacturing a spring contact pin using a precipitation hardening process capable of improving the strength and hardness of the spring contact pin through the precipitation hardening process.

[0002] An IC test socket consists of a number of contact probe pins arranged on a circuit board. The IC test socket connects the electrodes of a semiconductor device, such as an IC (integrated circuit) under test, to a test device (tester). By bringing the contact probe pins into contact with electrodes or tin solder on the semiconductor device, it is used for electrical testing.

[0003] Electrical testing of ICs (integrated circuits) is sometimes performed under a room temperature environment, but depending on the intended use of the IC, it may also be performed under a high temperature environment (e.g., 120°C to 160°C) that assumes the intended use environment.

[0004] As materials for these contact probe pins, Re-W alloys (e.g., patent document 1), Be-Cu alloys plated with Au, etc. (e.g., patent document 2), and precipitation-hardening Ag-Pd-Cu alloys (e.g., patent document 3) have been used.

[0005] The material of the contact probe pin used in the IC test socket is required to be one that can obtain good electrical resistance (low resistivity), one that can obtain stable contact resistance even after long-term use (oxidation resistance), and one that is difficult to wear out by repeated contact with the test object for hundreds to tens of thousands of times (high hardness).

[0006] However, the contact probe pin made of the above-described alloy does not sufficiently satisfy all requirements for the material of the contact probe pin in electrical inspection under a high-temperature environment.

[0007] Specifically, contact probe pins using W, such as Re-W alloys, have low resistivity, sufficient hardness, and excellent wear resistance. However, due to poor oxidation resistance in high-temperature environments, an insulating oxide film is formed on the surface, and this oxide may peel off and adhere to the inspection object, resulting in poor conductivity, making it difficult to obtain stable contact resistance values.

[0008] Contact probe pins using Be-Cu alloys plated with Au, etc., are excellent in that they have low resistivity. However, because the plating to prevent oxidation of the Be-Cu alloy peels off upon repeated contact with the inspection object, the wear resistance is poor. In addition, because the Au-Sn alloy, which is derived from the Sn component contained in the Sn-plated electrode or Sn solder of the inspection object and the Au plating component of the contact terminal, is easily eroded by repeated contact with the inspection object in a high-temperature environment, the contact resistance stability is poor.

[0009] Contact probe pins using Ag-Pd-Cu alloys contain a large amount of conductive precious metals and copper, resulting in low resistivity. Furthermore, precious metals are resistant to oxidation, eliminating the need for plating to prevent oxidation and offering excellent oxidation resistance. Furthermore, while not optimal for wear resistance, they are harder than Be-Cu alloys and rank second only to Re-W alloys in hardness.

[0010] From this comprehensive perspective, Ag-Pd-Cu alloys have been widely used as the material for conventional contact probe pins, but recently, in response to the high density of ICs (integrated circuits), the shape of the tip of the contact probe pin needs to be thinner and sharper, and the contact probe pin tends to be easily damaged and worn out. Accordingly, the material of the contact probe pin is required to have at least the same low resistivity and contact resistance stability (oxidation resistance) as before, and further mechanical strength and wear resistance (high hardness) are also required.

[0011] One of the various tasks of the present invention is to provide a method for manufacturing a spring contact pin that can extend the replacement cycle by increasing the hardness of the spring contact pin, reducing the wear rate, and reducing the resistance.

[0012] A method for manufacturing a spring contact pin using a precipitation hardening process according to exemplary embodiments of the present invention may include the steps of manufacturing a plurality of contact pins made of a copper alloy, performing a first heat treatment process for hardening the plurality of contact pins, performing an electroless nickel plating process using the plurality of contact pins subjected to the first heat treatment as a plated substrate to form a nickel plating layer, performing a second heat treatment process for precipitation hardening of the nickel plating layer, and manufacturing a spring contact pin by combining two contact pins among the plurality of contact pins as an upper contact pin and a lower contact pin, respectively, and interposing a spring between the upper contact pin and the lower contact pin.

[0013] The nickel plating layer can be formed on the upper contact pin and the lower contact pin, and can be controlled not to be formed on the spring.

[0014] The plating solution of the above electroless nickel plating process may be composed of at least one selected from the group consisting of nickel sulfate, sodium hypophosphite, sodium citrate, sodium acetate, sodium glycolate, lactic acid, malic acid, citric acid, succinic acid, propionic acid, and sodium acetate.

[0015] The plating solution of the above electroless nickel plating process may be composed of 20-30 parts by weight of nickel sulfate, 18-36 parts by weight of sodium hypophosphite, 20-40 parts by weight of sodium citrate, and 4-16 parts by weight of sodium acetate.

[0016] The plating solution of the above electroless nickel plating process may be composed of 25 parts by weight of nickel sulfate, 25 parts by weight of sodium hypophosphite, 30 parts by weight of sodium citrate, and 10 parts by weight of sodium acetate.

[0017] The plating solution of the above electroless nickel plating process may be composed of 25 parts by weight of nickel sulfate, 30 parts by weight of sodium hypophosphite, 30 parts by weight of sodium glycolate, and 20 parts by weight of sodium acetate.

[0018] The plating solution of the above electroless nickel plating process may be composed of 21 parts by weight of nickel sulfate, 24 parts by weight of sodium hypophosphite, 30 parts by weight of lactic acid, and 2 parts by weight of propionic acid.

[0019] The plating solution of the above electroless nickel plating process may be composed of 20 parts by weight of nickel sulfate, 24 parts by weight of sodium hypophosphite, 16 parts by weight of malic acid, and 18 parts by weight of succinic acid.

[0020] The plating solution of the above electroless nickel plating process may be composed of 23 parts by weight of nickel sulfate, 18 parts by weight of sodium hypophosphite, 20 parts by weight of lactic acid, and 12 parts by weight of succinic acid.

[0021] The plating solution of the above electroless nickel plating process may be composed of 30 parts by weight of nickel sulfate, 36 parts by weight of sodium hypophosphite, 15 parts by weight of lactic acid, 15 parts by weight of malic acid, 10 parts by weight of citric acid, and 5 parts by weight of succinic acid.

[0022] The above secondary heat treatment process can be performed by applying different temperature conditions depending on the phosphorus content of the nickel plating layer.

[0023] When the phosphorus content of the nickel plating layer is 1 to 4.5%, the secondary heat treatment process can be performed at a temperature of 380 to 420°C.

[0024] When the phosphorus content of the nickel plating layer is 4.5 to 11%, the secondary heat treatment process can be performed at a temperature of 250 to 290°C.

[0025] When the phosphorus content of the nickel plating layer is 9 to 10.5%, the secondary heat treatment process can be performed at a temperature of 400°C.

[0026] When the phosphorus content of the nickel plating layer exceeds 11%, the secondary heat treatment process can be performed at a temperature of 300 to 360°C.

[0027] The copper alloy may contain copper as the remainder, with 1.6 wt% to 2.0 wt% beryllium, 0.2 wt% or less of combined cobalt and nickel, 0.6 wt% or less of combined iron, nickel and cobalt, 0.02 wt% or less of lead, and 0.5 wt% or less of other impurities.

[0028] The above first heat treatment process can be performed at a temperature of 300°C to 330°C for 2 to 3 hours.

[0029] The nickel plating layer may be formed so that its thickness increases toward the edge portion of the upper contact pin and the lower contact pin.

[0030] An additional plating process for plating gold or silver on the above-mentioned manufactured spring contact pin is further included, wherein the gold plating layer or the silver plating layer can be formed on the nickel plating layer.

[0031] The nickel plating layer may have a thickness thicker than the gold plating layer or the silver plating layer.

[0032] Each feature of the above-described embodiments may be implemented in combination in other embodiments as long as it is not inconsistent with or exclusive of other embodiments.

[0033] A method for manufacturing a spring contact pin using a precipitation hardening process according to an exemplary embodiment of the present invention can increase the hardness of the manufactured spring contact pin by using a precipitation hardening process of a nickel plating layer.

[0034] A method for manufacturing a spring contact pin using a precipitation hardening process according to an exemplary embodiment of the present invention can reduce the occurrence of wear of the manufactured spring contact pin by using a precipitation hardening process of a nickel plating layer.

[0035] A method for manufacturing a spring contact pin using a precipitation hardening process according to an exemplary embodiment of the present invention can reduce the resistance of the manufactured spring contact pin by using a precipitation hardening process of a nickel plating layer.

[0036] A method for manufacturing a spring contact pin using a precipitation hardening process according to an exemplary embodiment of the present invention can increase the replacement cycle of the manufactured spring contact pin by using a precipitation hardening process of a nickel plating layer.

[0037] The effects of the present invention are not limited to those described above, and other effects not mentioned will be clearly recognized by those skilled in the art from the description below.

[0038] FIG. 1 is a flowchart illustrating a method for manufacturing a spring contact pin using a precipitation hardening process according to exemplary embodiments of the present invention.

[0039] FIG. 2 is an exploded view of a spring contact pin according to exemplary embodiments of the present invention.

[0040] FIG. 3 is an enlarged view of a spring contact pin manufactured using a precipitation hardening process according to exemplary embodiments of the present invention.

[0041] FIGS. 4 and 5 are enlarged cross-sectional views of spring contact pins manufactured using a precipitation hardening process according to exemplary embodiments of the present invention.

[0042] FIG. 6 is an enlarged cross-sectional view of an edge portion of a spring contact pin manufactured using a precipitation hardening process according to exemplary embodiments of the present invention.

[0043] Figures 7 and 8 show the results of a life cycle test of a spring contact pin manufactured using a conventional manufacturing method.

[0044] Fig. 9 is an enlarged cross-sectional view of the tip portion according to a life cycle test of a spring contact pin manufactured using a conventional manufacturing method.

[0045] Figure 10 is an enlarged cross-sectional view of a slide section according to a life cycle test of a spring contact pin manufactured using a conventional manufacturing method.

[0046] Figures 11 and 12 show the results of a life cycle test of a spring contact pin manufactured using the precipitation hardening process of the present invention.

[0047] Fig. 13 is an enlarged cross-sectional view of the tip portion of a spring contact pin manufactured using the precipitation hardening process of the present invention.

[0048] Fig. 14 is an enlarged cross-sectional view of the slide portion of a spring contact pin manufactured using the precipitation hardening process of the present invention.

[0049] FIG. 15 is a flowchart illustrating a method for manufacturing a spring contact pin using a precipitation hardening process according to another embodiment of the present invention.

[0050] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following detailed description is provided to facilitate a comprehensive understanding of the methods, devices, and / or systems described herein. However, these are merely examples and the present invention is not limited thereto.

[0051] In describing embodiments of the present invention, if a detailed description of a known technology related to the present invention is judged to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of their functions in the present invention, and this may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification. The terminology used in the detailed description is only for the purpose of describing embodiments of the present invention and should not be limited in any way. Unless clearly used otherwise, the singular form includes the plural form. In this description, expressions such as "comprises" or "having" are intended to indicate certain features, numbers, steps, operations, elements, parts or combinations thereof, and should not be construed to exclude the presence or possibility of one or more other features, numbers, steps, operations, elements, parts or combinations thereof other than those described.

[0052] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms.

[0053] Below, a method for manufacturing a spring contact pin using a precipitation hardening process is described in detail through drawings.

[0054] FIG. 1 is a flowchart illustrating a method for manufacturing a spring contact pin using a precipitation hardening process according to exemplary embodiments of the present invention.

[0055] Referring to FIG. 1, a method for manufacturing a spring contact pin using a precipitation hardening process according to exemplary embodiments of the present invention may include a contact pin manufacturing step (S100), a first heat treatment step (S200), a nickel plating layer forming step (S300), a second heat treatment step (S400), a spring contact pin manufacturing step (S500), and an additional plating process step (S600).

[0056] The contact pin manufacturing step (S100) may be a step of manufacturing a plurality of contact pins (11, 13) made of a copper alloy.

[0057] In one embodiment, the copper (Cu) alloy may include 1.6 wt% to 2.0 wt% beryllium (Be), 0.2 wt% or less of combined cobalt (Co) and nickel (Ni), 0.6 wt% or less of combined iron (Fe), nickel (Ni), and cobalt (Co), 0.02 wt% or less of lead (Pb), and 0.5 wt% or less of other impurities, with the remainder being copper.

[0058] More specifically, the copper alloy may comprise 1.8 wt% beryllium, 0.2 wt% or less of combined cobalt and nickel, 0.6 wt% or less of combined iron, nickel and cobalt, 0.02 wt% or less of lead, and 0.5 wt% or less of other impurities, with the remainder being copper, but the present invention is not necessarily limited thereto.

[0059] A plurality of contact pins (11, 13) manufactured by the contact pin manufacturing step (S100) may be subjected to a first heat treatment process (S200) for hardening.

[0060] In one embodiment, the first heat treatment process (S200) may be performed at a temperature of 300°C to 330°C for 2 to 3 hours. More specifically, it may be performed at a temperature of 315°C for 2 to 3 hours.

[0061] The above-mentioned first heat-treated plurality of contact pins (11, 13) can be subjected to a nickel plating layer forming step (S300) in which a nickel plating layer is formed by performing an electroless nickel plating process using the plurality of contact pins (11, 13) as a plating material.

[0062] The nickel plating layer may be formed on the plurality of contact pins (11, 13), and may be controlled not to be formed on the spring (15). More specifically, the nickel plating layer may be formed on the upper contact pin (11) and the lower contact pin (13). The structures of the upper contact pin (11) and the lower contact pin (13) will be described in more detail below with reference to FIG. 2.

[0063] The above nickel plating layer can be formed so that its thickness increases toward the edge portion of the upper contact pin (11) and the lower contact pin (13).

[0064] In the above electroless nickel plating process, the plating solution may be composed of at least one selected from the group consisting of nickel sulfate, sodium hypophosphite, sodium citrate, sodium acetate, sodium glycolic acid, lactic acid, malic acid, citric acid, succinic acid, propionic acid, and sodium acetate.

[0065] The plating solution of the above electroless nickel plating process may be composed of 20 to 30 parts by weight of nickel sulfate, 18 to 36 parts by weight of sodium hypophosphite, 20 to 40 parts by weight of sodium citrate, and 4 to 16 parts by weight of sodium acetate.

[0066] As an example, the plating solution of the electroless nickel plating process may be composed of 25 parts by weight of nickel sulfate, 25 parts by weight of sodium hypophosphite, 30 parts by weight of sodium citrate, and 10 parts by weight of sodium acetate.

[0067] As an example, the plating solution of the electroless nickel plating process may also be composed of 25 parts by weight of nickel sulfate, 30 parts by weight of sodium hypophosphite, 30 parts by weight of sodium glycolate, and 20 parts by weight of sodium acetate.

[0068] As an example, the plating solution of the electroless nickel plating process may be composed of 21 parts by weight of nickel sulfate, 24 parts by weight of sodium hypophosphite, 30 parts by weight of lactic acid, and 2 parts by weight of propionic acid.

[0069] As an example, the plating solution of the electroless nickel plating process may be composed of 20 parts by weight of nickel sulfate, 24 parts by weight of sodium hypophosphite, 16 parts by weight of malic acid, and 18 parts by weight of succinic acid.

[0070] As an example, the plating solution of the electroless nickel plating process may be composed of 23 parts by weight of nickel sulfate, 18 parts by weight of sodium hypophosphite, 20 parts by weight of lactic acid, and 12 parts by weight of succinic acid.

[0071] Additionally, as an example, the plating solution of the electroless nickel plating process may be composed of 30 parts by weight of nickel sulfate, 36 parts by weight of sodium hypophosphite, 15 parts by weight of lactic acid, 15 parts by weight of malic acid, 10 parts by weight of citric acid, and 5 parts by weight of succinic acid.

[0072] However, the present invention is not limited to the above-described embodiments.

[0073] After the nickel plating layer formation step (S300) is completed, a second heat treatment step (S400) may be performed to perform a second heat treatment process for precipitation hardening of the nickel plating layer. The second heat treatment process (S400) may be performed by applying different temperature conditions depending on the phosphorus content of the nickel plating layer.

[0074] As an example, when the phosphorus content of the nickel plating layer is 1 to 4.5%, the second heat treatment process (S400) may be performed at a temperature of 380 to 420°C.

[0075] As an example, when the phosphorus content of the nickel plating layer is 4.5 to 11%, the second heat treatment process (S400) may be performed at a temperature of 250 to 290°C. At this time, when the phosphorus content of the nickel plating layer is 9 to 10.5%, the second heat treatment process (S400) may be performed at a temperature of 400°C.

[0076] In addition, as an example, when the phosphorus content of the nickel plating layer exceeds 11%, the second heat treatment process (S400) may be performed at a temperature condition of 300 to 360°C.

[0077] After the above secondary heat treatment process (S400) is completed, the spring contact pin manufacturing step (S500) can be performed.

[0078] In the spring contact pin manufacturing step (S500), a spring contact pin (10) can be manufactured by combining two contact pins (11, 13) among the plurality of contact pins (11, 13) as an upper contact pin (11) and a lower contact pin (13), respectively, and interposing a spring (15) between the upper contact pin (11) and the lower contact pin (13). The structures of the upper contact pin (11), the lower contact pin (13), and the spring contact pin (10) will be described in more detail below with reference to FIG. 2.

[0079] After the spring contact pin manufacturing step (S500) is completed, an additional plating process step (S600) of plating gold or silver on the manufactured spring contact pin (10) can be performed.

[0080] At this time, the gold plating layer or the silver plating layer may be formed on the nickel plating layer. In addition, the nickel plating layer may have a thickness thicker than the gold plating layer or the silver plating layer.

[0081] The spring contact pin (10) according to the present invention may have a nickel plating layer formed on top of a copper alloy layer. By precipitation hardening the nickel plating layer, the hardness of the spring contact pin (10) is improved, thereby reducing the wear rate. Furthermore, by exhibiting stable resistance, the replacement cycle of the spring contact pin (10) can be extended.

[0082] FIG. 2 is an exploded view of a spring contact pin according to exemplary embodiments of the present invention.

[0083] Referring to FIG. 2, a spring contact pin (10) according to the present invention may include contact pins (11, 13) including an upper contact pin (11) and a lower contact pin (13) and a spring (15). At this time, the spring contact pin (10) may be assembled so that the upper contact pin (11) and the lower contact pin (13) are elastically supported by the spring (15), and the upper contact pin (11) and the lower contact pin (13) are intersected with respect to the spring (15).

[0084] According to one embodiment, the upper contact pin (11) and the lower contact pin (13) may be provided by contact pins having the same size and shape. The two contact pins (11, 13) are assembled in the longitudinal direction so as to be elastically supported by a spring (15), and may be distinguished as the upper contact pin (11) and the lower contact pin (13) depending on the assembled position. Therefore, the following description will be based on the upper contact pin (11).

[0085] The upper contact pin (11) may be composed of a body portion (111), a tip portion (112), a contact portion (113), a shoulder portion (115), a guide portion (114), and a leg portion (118).

[0086] The body part (111) can form a predetermined width and thickness (t1), and the body part (111) can include a tip part (112) and a contact part (113) that form a portion exposed to the outside of the spring (15) in the spring contact pin (10).

[0087] The contact portion (113) is formed at one end of the body portion (111) and can contact either the circuit pattern of the test printed circuit board installed in the test device or the contact ball or land of the BGA type or LGA type semiconductor IC when testing the semiconductor device (IC) through the test socket.

[0088] That is, when testing a semiconductor device (IC) through a test socket to which a spring contact pin (10) of the present embodiment is applied, when the contact portion (113) of the upper contact pin (11) comes into contact with the circuit pattern of the test printed circuit board installed in the test device, the contact portion (133) of the lower contact pin (113) comes into contact with the contact ball or land of the BGA type or LGA type semiconductor IC, thereby electrically connecting the test printed circuit board and the semiconductor IC.

[0089] The contact portion (113) may be formed as one or more contact portions in a shape in which the tip is sharp as at least one of the width of the tip portion (112) or the thickness (t1) of the tip portion (112) at one end of the body portion (111) becomes smaller.

[0090] However, this is just an example, and the contact portion (113) may be provided in a rounded shape at the tip according to the characteristics of the contact target, and may be provided in a V shape, U shape, crown shape, etc. so that multiple contact points of the circuit pattern of the inspection printed circuit board or the terminal ball / land of the BGA / LGA type semiconductor IC are formed.

[0091] The solder portion (115) may be formed to protrude in the width direction of the body portion (111). The shoulder portion (115) may be provided to protrude in a vertical direction from each of the left and right side ends of the body portion (111).

[0092] Each shoulder portion (115) may be provided at a position symmetrical to each other with respect to the body portion (111). The shoulder portion (115) protruding in a direction perpendicular to the body portion (111) from one side of the body portion (111) and the shoulder portion (115) protruding in a direction perpendicular to the body portion (111) from the other side of the body portion (111) may be provided in a shape symmetrical with respect to the body portion (111) by having the same degree of protrusion, shape, size, thickness, width, etc.

[0093] The first shoulder (1151R) can be formed by protruding at symmetrical positions on the left and right ends of the body portion (111) to form a wider width (W1) than the width of the tip portion (112) for positional alignment of the upper contact pin (11).

[0094] The second shoulder (1152R) may be formed at a position spaced apart from the first shoulder (1151R) by a predetermined distance in a direction away from the contact portion (113). The second shoulder (1152R) may support the elasticity of the spring (15) in the spring contact pin (10) of the present embodiment.

[0095] More specifically, the spring contact pin (10) can support the elasticity of the spring (15) by the second shoulder (1152R) of the upper contact pin (11) and the second shoulder (1152R) of the lower contact pin (13).

[0096] The guide portion (114) may be formed in a groove shape along the longitudinal direction of the body portion (111). Accordingly, the thickness (t1) formed by the guide portion (114) is formed to be smaller than the thickness (t1) of the body portion. In addition, the guide portion (114) may guide the up-and-down movement of the lower contact pin (13) when the lower contact pin (13) is cross-coupled to the upper contact pin (11).

[0097] That is, as described above, the upper contact pin (11) and the lower contact pin (13) can be joined with the spring (15) interposed in an intersecting direction to form a spring contact pin (10). In this structure, when the spring contact pin (10) is compressed, the engaging member (138) of the lower contact pin (13) can move along the length direction of the body portion (111) of the upper contact pin (11) along the guide portion (114) of the upper contact pin (11).

[0098] The leg portion (118) may be formed to extend in a direction opposite to the contact portion (113) along the longitudinal direction of the body portion (111). The leg portions (118) may be provided as a pair that are symmetrical to each other with respect to the center line of the body portion (111). The pair of leg portions (118) may have a predetermined elasticity so that the width (w3) of the leg portions (118) increases when the spring contact pin (10) is compressed.

[0099] In a conventional pogo-type spring contact structure, as the length of the spring contact pin increases, the thickness of the socket housing that accommodates the spring contact pin also increases, making it more difficult to process a pin hole in the socket housing that accommodates the spring contact pin.

[0100] In order to solve this problem as described above, the present embodiment discloses a contact pin (11, 13) having a first shoulder (1151, 1351) formed therein to assist in positional alignment of the contact pin (11, 13) when manufacturing the contact pin (11, 13).

[0101] If, like a conventional spring contact, there is no first shoulder (1151, 1351) and the contact pin is aligned within the pin hole by a protruding member (second shoulder: 1152, 1352 in the present embodiment) that supports the elasticity of the spring, the longer the length of the spring contact, the deeper the pin hole for accommodating the spring contact must be machined, with a smaller diameter to accommodate the tip of the contact pin, which makes processing difficult. In addition, as the length of the body of the contact pin increases, it is difficult to ensure the strength of the contact pin, which may cause a problem of deterioration in the quality of the product.

[0102] Even if the length of the spring is relatively increased to prevent the length of the tip of the contact pin from becoming longer, there is a clear structural limit when considering the elasticity of the spring, and as the length of the spring becomes longer, a problem of reduced elastic restoring force may occur.

[0103] Accordingly, if the lengths of the spring contact pins are formed differently, the distance between the first shoulder (2151) and the second shoulder (2152) can be formed longer than that of the spring contact pin (10) of FIG. 2 to solve the above-described problem, and the first shoulder (3151, 4151, 5151) can also be formed longer along the longitudinal direction of the body to solve the above-described problem. In addition, the upper contact pin (11) and the lower contact pin (13) can of course be formed to have different lengths according to the customer's requirements.

[0104] That is, the spring contact pin (10) according to the present embodiment can improve the quality of the test socket when the length of the spring contact pin (10) is manufactured in various ways according to the customer's needs, and when the length of the spring contact is manufactured in various ways according to the customer's performance requirements, the defect rate of the test socket can be reduced, thereby improving the product yield.

[0105] In addition, when manufacturing the body portion in various lengths for the spring contact pin (10) of various lengths reflecting the customer's performance requirements, the length of the tip portion may not be manufactured to be longer than necessary by manufacturing the first shoulder (3151, 4151, 5151) in proportion to the length of the body portion. Accordingly, by manufacturing a series of spring contact pins (10) of various lengths in which the lengths of the body portion and the first shoulder (3151, 4151, 5151) are proportional, the manufacturing time and cost can be reduced.

[0106] FIG. 3 is an enlarged view of a spring contact pin manufactured using a precipitation hardening process according to exemplary embodiments of the present invention, and FIGS. 4 and 5 are enlarged cross-sectional views of a spring contact pin manufactured using a precipitation hardening process according to exemplary embodiments of the present invention.

[0107] Referring to FIGS. 3 to 5, a spring contact pin (10) manufactured using a precipitation hardening process according to the present invention can be formed by joining an upper contact pin (11) and a lower contact pin (13) in a direction in which they intersect each other with a spring (15) therebetween.

[0108] The contact pins (11, 13) may be formed of a copper alloy layer and a nickel plating layer. In one spring contact pin (10), the thicknesses of the copper alloy layer and the nickel plating layer may not be constant.

[0109] As an example, the copper alloy layer may be formed to a thickness of 1.400 μm to 2.300 μm, and the nickel plating layer may be formed to a thickness of 0.300 μm to 1.300 μm.

[0110] The copper alloy layer may be formed to a thickness of 1.590 μm to 2.196 μm. More specifically, the copper alloy layer may be formed to a thickness of at least one of 1.590 μm, 1.621 μm, 1.706 μm, 2.196 μm, and 2.093 μm, but the present invention is not necessarily limited thereto.

[0111] The nickel plating layer may be formed to a thickness of 0.482 μm to 1.221 μm. More specifically, the nickel plating layer may be formed to a thickness of at least one of 0.482 μm, 0.487 μm, 0.493 μm, 1.067 μm, 1.170 μm, and 1.221 μm, but the present invention is not necessarily limited thereto.

[0112] FIG. 6 is an enlarged cross-sectional view of an edge portion of a spring contact pin manufactured using a precipitation hardening process according to exemplary embodiments of the present invention.

[0113] Referring to Fig. 6, in the contact pins (11, 13) manufactured using the precipitation hardening process according to the present invention, the nickel plating layer may be formed so that its thickness increases toward the edge portion of the contact pins (11, 13). That is, the nickel plating layers of the upper contact pin (11) and the lower contact pin (13) may be formed so that their thickness increases toward the edge portion.

[0114] FIG. 7 and FIG. 8 are the results of a life cycle test of a spring contact pin manufactured by a conventional manufacturing method, FIG. 9 is an enlarged cross-sectional view of a tip portion according to a life cycle test of a spring contact pin manufactured by a conventional manufacturing method, and FIG. 10 is an enlarged cross-sectional view of a slide portion according to a life cycle test of a spring contact pin manufactured by a conventional manufacturing method.

[0115] Referring to FIGS. 7 and 8, the life cycle test of a spring contact pin manufactured using a conventional manufacturing method showed that a large resistance deviation occurred after 300 K. In addition, the force (gf) of the spring contact pin manufactured using a conventional manufacturing method was found to be unstable, and the resistance (㏁) value also increased as the number of LTT (Life Time Test) operations increased.

[0116] Referring to FIGS. 9 and 10, the tip and slide portions of the spring contact pin manufactured using a conventional manufacturing method were found to develop cracks and wear as the number of LTT (Life Time Test) increases, which is caused by contact instability of the signal path and can be a major cause of increased resistance.

[0117] FIG. 11 and FIG. 12 are the results of a life cycle test of a spring contact pin manufactured using the precipitation hardening process of the present invention, FIG. 13 is an enlarged cross-sectional view of a tip portion of a spring contact pin manufactured using the precipitation hardening process of the present invention, and FIG. 14 is an enlarged cross-sectional view of a slide portion of a spring contact pin manufactured using the precipitation hardening process of the present invention.

[0118] Referring to FIGS. 11 and 12, as a result of a life cycle test of a spring contact pin (10) manufactured using the precipitation hardening process of the present invention, the hardness (Force, gf) was found to be higher than that of a spring contact pin manufactured using a conventional manufacturing method. In addition, the spring contact pin (10) manufactured using the manufacturing method of the present invention was found to have a lower and more stable Resistance (MΩ) value than that of a spring contact pin manufactured using a conventional manufacturing method.

[0119] Referring to FIGS. 13 and 14, the tip and slide portions of the spring contact pin (10) manufactured using the precipitation hardening process of the present invention show wear as the number of LTT (Life Time Test) increases, but the wear is found to be very low compared to the spring contact pin manufactured using a conventional manufacturing method.

[0120] That is, the spring contact pin (10) manufactured according to the manufacturing method of the present invention can exhibit improved hardness compared to the spring contact pin manufactured according to the conventional manufacturing method by utilizing a precipitation hardening process, thereby reducing wear and exhibiting stable resistance. Accordingly, the replacement cycle of the spring contact pin (10) can be extended.

[0121] FIG. 15 is a flowchart illustrating a method for manufacturing a spring contact pin using a precipitation hardening process according to another embodiment of the present invention.

[0122] The method for manufacturing a spring contact pin described with reference to Fig. 15 is substantially the same as or similar to the method for manufacturing a spring contact pin described with reference to Fig. 1, except that the heat treatment step is performed once after the nickel plating layer formation step. Therefore, a repeated description of the same configuration will be omitted.

[0123] Referring to FIG. 15, a method for manufacturing a spring contact pin using a precipitation hardening process according to another embodiment of the present invention may include a contact pin manufacturing step (S10), a nickel plating layer forming step (S20), a heat treatment step (S30), and a spring contact pin manufacturing step (S40).

[0124] The contact pin manufacturing step (S10) may be a step of manufacturing a plurality of contact pins (11, 13) made of a copper alloy.

[0125] In one embodiment, the copper (Cu) alloy may include 1.6 wt% to 2.0 wt% beryllium (Be), 0.2 wt% or less of combined cobalt (Co) and nickel (Ni), 0.6 wt% or less of combined iron (Fe), nickel (Ni), and cobalt (Co), 0.02 wt% or less of lead (Pb), and 0.5 wt% or less of other impurities, with the remainder being copper.

[0126] More specifically, the copper alloy may comprise 1.8 wt% beryllium, 0.2 wt% or less of combined cobalt and nickel, 0.6 wt% or less of combined iron, nickel and cobalt, 0.02 wt% or less of lead, and 0.5 wt% or less of other impurities, with the remainder being copper, but the present invention is not necessarily limited thereto.

[0127] A plurality of contact pins (11, 13) manufactured by the contact pin manufacturing step (S10) can be subjected to a nickel plating layer forming step (S20) by performing an electroless nickel plating process on the contact pins (11, 13) without being separately heat-treated to form a nickel plating layer.

[0128] The nickel plating layer may be formed on the plurality of contact pins (11, 13), and may be controlled not to be formed on the spring (15). More specifically, the nickel plating layer may be formed on the upper contact pin (11) and the lower contact pin (13).

[0129] The above nickel plating layer can be formed so that its thickness increases toward the edge portion of the upper contact pin (11) and the lower contact pin (13).

[0130] In the above electroless nickel plating process, the plating solution may be composed of at least one selected from the group consisting of nickel sulfate, sodium hypophosphite, sodium citrate, sodium acetate, sodium glycolic acid, lactic acid, malic acid, citric acid, succinic acid, propionic acid, and sodium acetate.

[0131] The plating solution of the above electroless nickel plating process may be composed of 20 to 30 parts by weight of nickel sulfate, 18 to 36 parts by weight of sodium hypophosphite, 20 to 40 parts by weight of sodium citrate, and 4 to 16 parts by weight of sodium acetate.

[0132] After the nickel plating layer formation step (S20) is completed, a heat treatment step (S30) may be performed to perform heat treatment for precipitation hardening of the plated material and the nickel plating layer.

[0133] In exemplary embodiments, the heat treatment step (S30) may be performed by sequentially performing a first heat treatment process performed at a relatively low temperature and a second heat treatment process performed at a relatively high temperature.

[0134] The above first heat treatment process can be performed at a temperature of 300°C to 330°C for 2 to 3 hours, and more specifically, can be performed at a temperature of 315°C for 2 to 3 hours.

[0135] The secondary heat treatment process (S400) can be performed by applying different temperature conditions depending on the phosphorus content of the nickel plating layer.

[0136] As an example, when the phosphorus content of the nickel plating layer is 1 to 4.5%, the second heat treatment process (S400) may be performed at a temperature of 380°C to 420°C.

[0137] As an example, when the phosphorus content of the nickel plating layer is 4.5 to 11%, the second heat treatment process (S400) may be performed at a temperature of 250°C to 290°C. At this time, when the phosphorus content of the nickel plating layer is 9 to 10.5%, the second heat treatment process (S400) may be performed at a temperature of 400°C.

[0138] In addition, as an example, when the phosphorus content of the nickel plating layer exceeds 11%, the secondary heat treatment process (S400) may be performed at a temperature of 300°C to 360°C.

[0139] Alternatively, the heat treatment step (S30) may be performed by performing either only the first heat treatment process performed at a relatively low temperature or only the second heat treatment process performed at a relatively high temperature. That is, for example, the heat treatment step (S30) may be completed by performing only the first heat treatment process or only the second heat treatment process.

[0140] After the above heat treatment step (S30) is completed, the spring contact pin manufacturing step (S40) can be performed.

[0141] In the spring contact pin manufacturing step (S40), a spring contact pin (10) can be manufactured by combining two contact pins (11, 13) among the plurality of contact pins (11, 13) as an upper contact pin (11) and a lower contact pin (13), respectively, and interposing a spring (15) between the upper contact pin (11) and the lower contact pin (13).

[0142] Meanwhile, although not shown, after the spring contact pin manufacturing step (S40) is completed, an additional plating process step (not shown) of plating gold or silver on the manufactured spring contact pin (10) may be performed.

[0143] At this time, the gold plating layer or the silver plating layer may be formed on the nickel plating layer. In addition, the nickel plating layer may have a thickness thicker than the gold plating layer or the silver plating layer.

[0144] The spring contact pin (10) according to the present invention may have a nickel plating layer formed on top of a copper alloy layer. By precipitation hardening the nickel plating layer, the hardness of the spring contact pin (10) is improved, thereby reducing the wear rate. Furthermore, by exhibiting stable resistance, the replacement cycle of the spring contact pin (10) can be extended.

[0145] While various embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that various modifications to the above-described embodiments are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims set forth below but also by equivalents thereof.

Claims

1. A step of manufacturing a plurality of contact pins made of copper alloy; A step of performing a first heat treatment process for hardening the plurality of contact pins; A step of forming a nickel plating layer by performing an electroless nickel plating process using the plurality of contact pins subjected to the first heat treatment as a plating material; A step of performing a secondary heat treatment process for precipitation hardening of the nickel plating layer; and A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that it comprises the step of manufacturing a spring contact pin by combining two contact pins among the plurality of contact pins as an upper contact pin and a lower contact pin, respectively, and interposing a spring between the upper contact pin and the lower contact pin.

2. In paragraph 1, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the nickel plating layer is formed on the upper contact pin and the lower contact pin, and is controlled so as not to be formed on the spring.

3. In paragraph 1, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the plating solution of the electroless nickel plating process comprises at least one selected from the group consisting of nickel sulfate, sodium hypophosphite, sodium citrate, sodium acetate, sodium glycolate, lactic acid, malic acid, citric acid, succinic acid, propionic acid, and sodium acetate.

4. In paragraph 1, The plating solution of the above electroless nickel plating process is: 20-30 parts by weight of nickel sulfate; 18-36 parts by weight of sodium hypophosphite; 20-40 parts by weight of sodium citrate; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 4-16 parts by weight of sodium acetate.

5. In paragraph 1, The plating solution of the above electroless nickel plating process is: 25 parts by weight of nickel sulfate; 25 parts by weight of sodium hypophosphite; 30 parts by weight of sodium citrate; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 10 parts by weight of sodium acetate.

6. In paragraph 1, The plating solution of the above electroless nickel plating process is: 25 parts by weight of nickel sulfate; 30 parts by weight of sodium hypophosphite; 30 parts by weight of sodium glycolate; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 20 parts by weight of sodium acetate.

7. In paragraph 1, The plating solution of the above electroless nickel plating process is: 21 parts by weight of nickel sulfate; 24 parts by weight of sodium hypophosphite; 30 parts by weight of lactic acid; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 2 parts by weight of propionic acid.

8. In paragraph 1, The plating solution of the above electroless nickel plating process is: 20 parts by weight of nickel sulfate; 24 parts by weight of sodium hypophosphite; 16 parts by weight of malic acid; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 18 parts by weight of succinic acid.

9. In paragraph 1, The plating solution of the above electroless nickel plating process is: 23 parts by weight of nickel sulfate; 18 parts by weight of sodium hypophosphite; 20 parts by weight of lactic acid; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 12 parts by weight of succinic acid.

10. In paragraph 1, The plating solution of the above electroless nickel plating process is: 30 parts by weight of nickel sulfate; 36 parts by weight of sodium hypophosphite; 15 parts by weight of lactic acid; 15 parts by weight of malic acid; 10 parts by weight of citric acid; and A method for manufacturing a spring contact pin using a precipitation hardening process characterized by comprising 5 parts by weight of succinic acid.

11. In paragraph 1, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the secondary heat treatment process is performed by applying different temperature conditions depending on the phosphorus content of the nickel plating layer.

12. In paragraph 11, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the secondary heat treatment process is performed at a temperature condition of 380°C to 420°C when the phosphorus content of the nickel plating layer is 1 to 4.5%.

13. In paragraph 11, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that when the phosphorus content of the nickel plating layer is 4.5 to 11%, the secondary heat treatment process is performed at a temperature condition of 250°C to 290°C.

14. In paragraph 13, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that when the phosphorus content of the nickel plating layer is 9 to 10.5%, the secondary heat treatment process is performed at a temperature condition of 400°C.

15. In paragraph 11, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that when the phosphorus content of the nickel plating layer exceeds 11%, the secondary heat treatment process is performed at a temperature condition of 300°C to 360°C.

16. In paragraph 1, The above copper alloy is, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that it comprises 1.6 to 2.0 wt% of beryllium, 0.2 wt% or less of combined cobalt and nickel, 0.6 wt% or less of combined iron, nickel and cobalt, 0.02 wt% or less of lead, and 0.5 wt% or less of other impurities, with the remainder being copper.

17. In paragraph 1, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the first heat treatment process is performed at a temperature of 300°C to 330°C for 2 to 3 hours.

18. In paragraph 1, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the nickel plating layer is formed so that its thickness increases toward the edge portion of the upper contact pin and the lower contact pin.

19. In paragraph 1, It further includes an additional plating process for plating gold or silver on the above-mentioned manufactured spring contact pin; A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the gold plating layer or the silver plating layer is formed on the nickel plating layer.

20. In paragraph 19, A method for manufacturing a spring contact pin using a precipitation hardening process, characterized in that the nickel plating layer has a thickness thicker than the gold plating layer or the silver plating layer.

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