JP2005232484A - Terminal, and component and product having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low cost terminal in which the prevention in the production of whiskers and satisfactory solderability at a low temperature are made to coexist, and a surface coating layer is made thin and uniform. <P>SOLUTION: In the terminal, an Sn layer is formed on the whole face or a part of an electrically conductive substrate, and an Sn alloy layer is formed on the Sn layer. The Sn layer is the one with a thickness of 0.1 to 20 μm composed of Sn and formed by electroplating. The Sn alloy layer is the one with a thickness of 0.1 to 20 μm composed of Sn and formed by electroplating. The Sn alloy layer is the one with a thickness of 0.1 to 20 μ composed of any one selected from an Sn-Ag binary alloy, an Sn-Ag-Cu ternary alloy, and an Sn-Ag-Cu-Bi quarternary alloy and formed by electroplating. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to terminals widely used for connection in electrical, electronic products, semiconductor products, automobiles, cables, solar cells, etc. (for example, connector terminals, relay terminals, slide switch terminals, bumps, solder terminals, flat cables) Terminals, etc., and more specifically, terminals particularly suitable for applications where solderability and contact reliability are required, and parts having the terminals (for example, connectors, relays, slide switches, flat cables, resistors, capacitors) , Coils, substrates, etc.) and products having the same (for example, semiconductor products, electrical products, electronic products, solar cells, automobiles, etc.).

  In various products and parts such as semiconductor products, electrical products, electronic products, automobiles, cables, solar cells, etc., means for conducting electricity include soldering and contact using terminals made of conductive substrates. Can do.

  Such terminals are usually Au, Ag, Pd, Cu, Ni, In, Sn, and Sn− for the purpose of improving solderability and improving corrosion resistance with respect to the surface of the conductive substrate. The surface is coated with a metal such as a Pb alloy (for example, Patent Document 1). Among these metals, it is most common to use Sn and Sn—Pb alloys in view of cost and the like, and the electroplating method is often adopted as the coating method.

  However, when Sn was electroplated alone, a huge columnar single crystal was generated in such a surface coating layer, and this caused the generation of whiskers. When a whisker is generated, it causes an electrical short circuit, so that it is required to prevent the whisker from occurring.

  As one means for preventing the generation of such whiskers, conventionally, alloying of Sn, that is, the use of Sn—Pb alloy or the like has been attempted. However, since Pb is a toxic metal as well known, Its use is restricted due to consideration.

  Then, development of the method of forming the various Sn type | system | group alloys replaced with a Sn-Pb alloy by electroplating is tried. For example, the Sn—Cu alloy has a minimum melting point (227 ° C.) at Sn 99.3 mass% and Cu 0.7 mass% and exhibits good solderability, but has a low Cu content, so whiskers (columnar crystals) ) Cannot be effectively prevented. On the other hand, when the Cu content is increased, the melting point is rapidly increased, so that the solderability is deteriorated.

  On the other hand, when an Sn-based alloy other than the Sn-Pb alloy is formed by electroplating, when Sn or Sn alloy is used as the anode, the alloy-forming element present in the plating solution is deposited on the anode surface (so-called substitution phenomenon). In some cases, electroplating cannot be performed. For this reason, considerable cost must be invested in the maintenance of the anode, resulting in an increase in production cost.

  On the other hand, a method of supplying all the alloy constituent elements containing Sn as a salt to the plating bath without using Sn or an Sn alloy as an anode is conceivable. In order to form the Sn alloy layer, a large amount of expensive salt must be used, and the cost requirement cannot be satisfied.

  As described above, a terminal formed by electroplating with a Sn-based alloy that has both a prevention of whisker generation and good solderability (that is, a low melting point) and also satisfies cost requirements has been developed. Not in the current situation.

  For the purpose of simply bonding the terminals as described above, an Sn-based alloy may be used for molten solder such as solder dip or cream solder. As such an Sn-based alloy, Sn, Ag, Cu, etc. An alloy made of may be used.

  However, Sn-based alloys that are used in this way are obtained by simply thermally melting (melting solder) each metal such as Sn, Ag, Cu, etc. (or an ingot obtained by melting and mixing these metals). Since only the adhesive action was exhibited and the coating thickness could not be controlled, it was not possible to uniformly coat the terminal with a thin thickness of 100 μm or less.

If the film cannot be uniformly coated with such a thin thickness, it not only lacks stability in appearance properties, but also causes an electrical short circuit. Moreover, pinholes and the like are easily generated, and the corrosion resistance is deteriorated.
JP-A-1-298617

  The present invention has been made in view of the present situation as described above, and the object of the present invention is to achieve both prevention of whisker generation and good solderability at low temperatures, and reduce the thickness of the surface coating layer. It is another object of the present invention to provide a terminal that is uniform and inexpensive in terms of cost.

  The terminal of the present invention is formed by forming a Sn layer on the entire surface or part of a conductive substrate, and forming an Sn alloy layer on the Sn layer, and the Sn layer is formed by electroplating. A Sn layer having a thickness of 0.1 to 20 μm, and the Sn alloy layer is formed by electroplating and has a thickness of 0.1 to 20 μm, Sn—Ag binary alloy, Sn—Ag—Cu ternary alloy, Or it is the layer which consists of either Sn-Ag-Cu-Bi quaternary alloy, It is characterized by the above-mentioned.

  The Sn layer can be formed by immersing the conductive substrate in a plating bath and electroplating using Sn as an anode, and the Sn alloy layer is formed by forming the Sn layer. Is immersed in a plating bath, and a metal other than Sn and Sn alloy is used as an anode, and each element constituting the Sn alloy is supplied as a salt, and then electroplated.

  The Sn-Ag binary alloy can be configured with a content ratio in which Ag is 0.1 to 20% by mass and the balance is Sn. The Sn-Ag-Cu ternary alloy has an Ag of 0.1 to 0.1%. 20 mass%, Cu can be comprised at a content ratio of 0.1 to 20 mass%, and the balance is Sn. The Sn—Ag—Cu—Bi quaternary alloy has an Ag content of 0.1 to 20 mass%. , Cu is 0.1 to 20% by mass, Bi is 0.1 to 20% by mass, and the balance is Sn.

  The conductive substrate may be a metal or a metal layer on the surface of an insulating substrate, and a base layer may be formed between the conductive substrate and the Sn layer.

  The electroplating can be performed using any of a barrel plating apparatus, a hook plating apparatus, or a continuous plating apparatus.

  The Sn layer can be matte plating, and the Sn alloy layer can be matte or semi-gloss plating.

  The terminal can be any of a connector terminal, a relay terminal, a slide switch terminal, a bump, a solder terminal, or a flat cable terminal.

  The component of the present invention has the above-described terminal, and can be any of a connector, a relay, a slide switch, a flat cable, a resistor, a capacitor, a coil, or a substrate.

  The product of the present invention has the terminal, and can be any one of a semiconductor product, an electrical product, an electronic product, a solar cell, or an automobile.

  The terminal manufacturing method of the present invention is a terminal manufacturing method in which an Sn layer is formed on the whole or part of a conductive substrate, and an Sn alloy layer is formed on the Sn layer. A step of forming an Sn layer on the whole or part of the conductive substrate by immersing in a plating bath and electroplating with Sn as an anode; and immersing the conductive substrate on which the Sn layer is formed in a plating bath; And forming a Sn alloy layer on the Sn layer by electroplating by using a metal other than the Sn alloy as an anode and supplying each element constituting the Sn alloy as a salt.

  The terminal of the present invention has the above-described configuration, in particular, a configuration in which a specific Sn layer is formed on a conductive substrate and a specific Sn alloy layer is formed thereon, so that the Sn alloy layer is Sn In addition to preventing the formation of whiskers in the layer, it provides a good solderability because of its low melting point. In addition, since the layer covering the terminal surface (surface coating layer) is formed by both the Sn layer and the Sn alloy layer, compared with the case where the surface coating layer is formed by the Sn alloy layer alone, the electroplating is performed. The amount of elemental salt constituting the Sn alloy to be used can be suppressed, so that the cost is excellent. Furthermore, by forming these surface coating layers by electroplating, the thickness of the surface coating layers can be made thin and uniform, and pinholes and electrical shorts can be prevented.

<Terminal>
The terminal of the present invention is characterized in that a Sn layer is formed on the entire surface or part of a conductive substrate, and an Sn alloy layer is formed on the Sn layer.

  Such terminals include, for example, those that are electrically conducted by soldering and those that are electrically conducted by contact so that the functions intended by the components and products described below can be sufficiently exhibited. Further, such a terminal can be suitably used for applications that require high corrosion resistance and stability in appearance.

  Specific examples of such terminals include connector terminals, relay terminals, slide switch terminals, bumps, solder terminals, flat cable terminals, and the like. For example, resistance terminals, capacitor terminals, Examples include a coil terminal.

  Further, such terminals include circuits (wiring portions) of circuit boards, vias, and the like, as well as flat cables, electric wires, lead portions of solar cells, and the like.

<Conductive substrate>
As the conductive substrate constituting the terminal of the present invention, any conventionally known conductive substrate used for applications such as electric, electronic products, semiconductor products, and automobiles can be used.

  As such a conductive substrate, a metal or a substrate on which a metal is laminated on an insulating substrate can be suitably used. For example, copper alloy materials such as copper (Cu), phosphor bronze, brass, beryllium copper, titanium copper, white (Cu, Ni, Zn), iron alloys such as iron (Fe), Fe-Ni alloy, stainless steel Examples thereof include metals such as nickel-based materials and other nickel-based materials, and those obtained by laminating such metals on at least the surface of an insulating substrate such as a polymer fill or ceramic. Therefore, for example, copper patterns on various substrates are included.

  As described above, suitable examples of the conductive substrate of the present invention include those in which a metal layer (that is, various circuit patterns) is formed on an insulating substrate made of various metals, polymer films, ceramics, or the like. Can be mentioned.

  The shape of such a conductive substrate is not limited to a flat shape such as a tape shape, but also includes a three-dimensional shape such as a press-molded product, and any other shape. There is no problem.

<Surface coating layer>
The surface coating layer of the terminal of the present invention is a term used for convenience in the present invention, and is a layer that covers the surface of the terminal, and is an Sn layer formed on the entire surface or part of the conductive substrate. These are generic names including both the Sn alloy layer formed on the Sn layer.

<Sn layer>
The Sn layer of the present invention is formed on the entire surface or part of the conductive substrate, and is a layer made of Sn having a thickness of 0.1 to 20 μm formed by electroplating. Such an Sn layer is composed of Sn alone except for inevitable impurities.

  As for the thickness of the Sn layer, an arbitrary thickness within the above range can be selected according to the purpose and use of the terminal, but the upper limit is more preferably 12 μm, still more preferably 8 μm, and the lower limit is set to 0. It is preferable that the thickness is 5 μm, more preferably 1.5 μm.

  Moreover, such a Sn layer is formed by electroplating as described above. This is because, when it is formed not by electroplating but by molten solder or reflow, it is difficult to control the thickness itself, and a thin and uniform Sn layer cannot be formed. If the thickness cannot be controlled in this way, an electrical short circuit or a pinhole is caused.

  Further, such an Sn layer is preferably matte plating by electroplating as described above. The matte plating can be performed by using a plating bath that does not contain a so-called secondary additive added for the purpose of imparting luster and contains only a so-called primary additive.

  As such a primary additive, any conventionally known additive can be used. For example, SBS-M (manufactured by Yuken Industry) or 513Y (manufactured by Ishihara Pharmaceutical) What is marketed can be illustrated.

<Sn alloy layer>
The Sn alloy layer of the present invention is formed on the Sn layer, and is formed by electroplating and has a thickness of 0.1 to 20 μm, Sn—Ag binary alloy, Sn—Ag—Cu ternary. It is a layer made of either an alloy or a Sn—Ag—Cu—Bi quaternary alloy. These Sn alloys are constituted by the content ratios (alloy ratios) described later only with the respective alloy constituent elements except for the inclusion of inevitable impurities.

  Although these alloys depend on the content ratio, Sn-Ag-Cu ternary alloys tend to exhibit a lower melting point than Sn-Ag binary alloys, and Sn-Ag-Cu ternary alloys. Sn-Ag-Cu-Bi quaternary alloys tend to exhibit a lower melting point than any of these three types of alloys, depending on the desired application and soldering temperature. It can be selected and used. That is, the reason why these three types of alloys are selected as the Sn alloy layer is to enrich the selection of their melting points.

  The thickness of the Sn alloy layer can be selected from any thickness within the above range depending on the purpose and application of the terminal, but the upper limit is more preferably 5 μm, and even more preferably 1 It is preferable that the lower limit is 0.5 μm, and the lower limit is 0.3 μm, more preferably 0.5 μm. If the thickness is less than 0.1 μm, it may not be possible to prevent whisker generated in the Sn layer from protruding to the surface, and even if the thickness exceeds 20 μm, the whisker's protrusion prevention effect is very different. On the contrary, it becomes economically disadvantageous.

  Here, the said Sn-Ag binary alloy is comprised by the content ratio from which Ag will be 0.1-20 mass%, and the remainder will be Sn. More preferably, the upper limit of the content ratio of Ag is 10% by mass, more preferably 5% by mass, and the lower limit is 1% by mass, more preferably 2.5% by mass. When the Ag content is less than 0.1% by mass, whisker generation is promoted, and when it exceeds 20% by mass, the melting point becomes high and good solderability is not exhibited.

  The Sn-Ag-Cu ternary alloy is composed of a content ratio in which Ag is 0.1 to 20% by mass, Cu is 0.1 to 20% by mass, and the balance is Sn. More preferably, the upper limit of the content ratio of Ag is 10% by mass, more preferably 5% by mass, and the lower limit is 1% by mass, more preferably 2.5% by mass. When the Ag content is less than 0.1% by mass, whisker generation is promoted, and when it exceeds 20% by mass, the melting point becomes high and good solderability is not exhibited. On the other hand, the Cu content ratio is more preferably 8% by mass, more preferably 3% by mass, and 0.2% by mass, and still more preferably 0.3% by mass. When the Cu content is less than 0.1% by mass, whisker generation is promoted, and when it exceeds 20% by mass, the melting point becomes high and good solderability is not exhibited.

  In the Sn-Ag-Cu-Bi quaternary alloy, Ag is 0.1 to 20% by mass, Cu is 0.1 to 20% by mass, Bi is 0.1 to 20% by mass, and the remainder is Sn. Consists of content ratio. More preferably, the upper limit of the content ratio of Ag is 10% by mass, more preferably 5% by mass, and the lower limit is 1% by mass, more preferably 2.5% by mass. When the Ag content is less than 0.1% by mass, whisker generation is promoted, and when it exceeds 20% by mass, the melting point becomes high and good solderability is not exhibited. On the other hand, the Cu content ratio is more preferably 8% by mass, more preferably 3% by mass, and 0.2% by mass, and still more preferably 0.3% by mass. When the Cu content is less than 0.1% by mass, whisker generation is promoted, and when it exceeds 20% by mass, the melting point becomes high and good solderability is not exhibited. Furthermore, the upper limit of the Bi content ratio is more preferably 15% by mass, further preferably 10% by mass, and the lower limit thereof is 0.5% by mass, and more preferably 1% by mass. When the Bi content is less than 0.1% by mass, whisker generation is promoted, and when it exceeds 20% by mass, brittleness increases and sufficient strength cannot be obtained.

  Such an Sn alloy preferably has an alloy ratio as described above, so that its melting point is 140 to 240 ° C, more preferably its upper limit is 230 ° C, more preferably 215 ° C, and its lower limit is 150. ° C, more preferably 180 ° C. By showing the melting point in such a range, good low-temperature solderability is shown.

  In addition, although the melting point of the Sn alloy of the present application shows the low melting point as described above in the state of the alloy alone, in the case of forming on the Sn layer by electroplating, the melting point in the state of the alloy alone Tends to exhibit a lower melting point. This is considered to be because when the Sn alloy is formed by electroplating, it exists as an aggregate of fine crystal particles as described later.

  When the Sn alloy layer is formed on the Sn layer in this manner, the surface exhibits good solderability (that is, low melting point) and whisker generation by the Sn layer can be prevented. In particular, as is apparent from a comparison between FIG. 1 and FIG. 2, a terminal in which a Sn—Ag—Cu ternary alloy is formed as an Sn alloy layer (thickness about 1.5 μm) on a Sn layer (thickness about 1.5 μm). In FIG. 1, which is a micrograph of a cross section using an FIB apparatus, whisker generation is prevented by the presence of a large number of small crystals made of an Sn alloy on a huge columnar crystal of Sn. In FIG. 2, which is a micrograph of the cross section of the terminal on which only the Sn layer is formed, there is a huge columnar crystal, which indicates that this causes the generation of whiskers.

  Furthermore, since such an Sn alloy layer is formed by electroplating, the thickness can be made thin and uniform, and the hardness thereof can be freely controlled. In addition, when the Sn alloy layer is formed by a method other than electroplating, it is impossible to exhibit the formation of fine crystal particles as shown in FIG.

  When the Sn alloy layer is formed of fine crystal particles as in the present invention, various additives present in the voids between the crystal particles act as impurities for the crystal particles and melt at a lower temperature during soldering. As a result, the solderability is further improved.

  On the other hand, when the Sn alloy layer is formed not by electroplating but by molten solder or reflow, the internal structure is formed not in the form of fine crystal particles but in the form of a lump, so that good solderability is expected. I can't do that. In addition, it is difficult to control the thickness of the Sn alloy layer itself, and it is impossible to form a thin and uniform surface coating layer, which causes electrical shorts and pinholes. End up. In addition, when the conductive substrate has a complicated shape, the Sn alloy layer cannot be uniformly formed over the entire surface of the conductive substrate, and may even be a lump that incorporates the entire conductive substrate.

  By forming the Sn alloy layer by electroplating as in the present invention, the above drawbacks can be overcome.

  In addition, it is preferable that such an Sn alloy layer is matte plating or semi-gloss plating by electroplating as described above. In order to achieve matte plating, as described above, it is possible to use a plating bath that does not contain so-called secondary additives added for the purpose of imparting gloss, but contains only so-called primary additives. it can. On the other hand, semi-gloss plating can be performed by using a plating bath containing a small amount of a secondary additive in addition to the primary additive.

  As such a primary additive, the same ones as described above can be used, and as the secondary additive, any conventionally known additive can be used, For example, LSA (manufactured by Yuken Industry) 2 (made by Ishihara Pharmaceutical Co., Ltd.) can be exemplified.

<Underlayer>
The underlayer of the present invention is formed as desired between the conductive substrate and the Sn layer, and has the following effects.

  That is, such a base layer has the effect of improving the adhesion between the conductive substrate and the Sn layer in principle. For example, when the conductive substrate is made of iron, rust is generated. In addition, when the conductive substrate is made of brass, it can also have an effect of preventing zinc contained in the brass from diffusing into the Sn layer.

  Therefore, the formation of such an underlayer can be selected according to the type of the conductive substrate (this point may not require the formation of the underlayer depending on the type of the conductive substrate), and its thickness Can be arbitrarily selected according to the type of the conductive substrate.

  The material constituting such an underlayer can be arbitrarily selected according to the type of the conductive substrate, but can be formed of, for example, Ni or Cu.

  When the underlayer is formed of Ni, it can be preferably formed by electroplating, and a Watt bath or a sulfamic acid bath can be used. On the other hand, when the underlayer is formed of Cu, it can be preferably formed by electroplating, and a copper cyanide bath or a copper sulfate bath can be used.

  Moreover, the thickness of such an underlayer can be preferably 0.01 to 20 μm, and more preferably 0.5 to 5 μm. When the thickness is less than 0.01 μm, the above-described effect cannot be sufficiently achieved, and even if the thickness exceeds 20 μm, there is not much difference in the above-described effect, which is economically disadvantageous.

<Electroplating equipment>
As described above, the Sn layer, the Sn alloy layer and the underlayer of the present invention are usually formed by electroplating. Particularly, as the electroplating apparatus, any of a barrel plating apparatus, a hook plating apparatus or a continuous plating apparatus is used. It is preferable to execute by using these. By using these devices, the terminals can be manufactured very efficiently.

  Here, the barrel plating apparatus is an apparatus for individually plating the terminals one by one, and the continuous plating apparatus is an apparatus for continuously plating a plurality of terminals at a time, and the hook plating apparatus is It is an intermediate device between the former two and has medium-scale production efficiency. These apparatuses are well known in the plating industry, and any apparatus having a known structure can be used.

<Parts>
The component of this invention has the said terminal. Examples include connectors, relays, slide switches, flat cables, resistors, capacitors, coils, electrical parts used as substrates, electronic parts, semiconductor parts, solar battery parts, automobile parts, etc. It is not something that can be done, nor is it a question of its shape.

<Product>
The product of this invention has the said terminal. For example, a semiconductor product, an electrical product, an electronic product, a solar cell, an automobile, and the like can be given, but the invention is not limited to these.

<Manufacturing method of terminal>
The method for manufacturing a terminal of the present invention is a method for manufacturing a terminal in which an Sn layer is formed on the entire surface or part of a conductive substrate, and an Sn alloy layer is formed on the Sn layer. A step of forming a Sn layer on the whole or part of the conductive substrate by immersing in a plating bath and electroplating with Sn as an anode; and immersing the conductive substrate on which the Sn layer is formed in a plating bath; And forming a Sn alloy layer on the Sn layer by electroplating by using a metal other than the Sn alloy as an anode and supplying each element constituting the Sn alloy as a salt. Yes.

  However, the manufacturing method is not limited to this. For example, in the step of forming the Sn alloy layer, Sn is used as an anode and an alloy constituent element other than Sn is supplied as a salt, or an Sn alloy is used as an anode. The method of using can also be employ | adopted.

  Moreover, the manufacturing method of the terminal of this invention can include a pre-processing process, a base layer formation process, etc. besides said each step. More specific description will be given below.

<Pretreatment process>
First, in the method for manufacturing a terminal according to the present invention, prior to the step of forming a surface coating layer made of an Sn layer and an Sn alloy layer on the entire surface or part of the conductive substrate, before the pretreatment of the conductive substrate. Processing steps can be included.

  This pretreatment step is performed for the purpose of forming the surface coating layer stably with high adhesion and without occurrence of pinholes. That is, the main purpose is to remove dirt and oxide adhering to the surface of the conductive substrate. This pretreatment step is particularly effective when the conductive substrate is a rolled metal such as phosphor bronze.

  Such a pretreatment step can be performed by causing an acid having a pH of 5 or less to act on the portion of the conductive substrate on which the surface coating layer is formed (acid treatment). Furthermore, the pretreatment process of the present invention includes a first cleaning process in which the conductive substrate is immersed in an aqueous solution, a second cleaning process in which the conductive substrate is electrolyzed in the aqueous solution, and an acid having a pH of 5 or less. And acid treatment to act on the substrate. In addition, it is preferable to include the water washing process 3-4 times between each of these processes.

  More specifically, the first cleaning process is performed by first immersing the conductive substrate in a tank filled with an aqueous solution, and the water washing is repeated several times.

  Here, the pH of the aqueous solution in the first cleaning treatment is preferably 0.01 or more, and more preferably, the treatment is performed with an alkali having a pH of 9 or more. Further specifying the pH range, the upper limit is 13.8, more preferably 13.5, while the lower limit of the pH is 9.5, more preferably 10. If the pH is less than 0.01 or the pH exceeds 13.8, the surface of the conductive substrate is excessively roughened or deteriorated.

  In addition, as long as it becomes the said pH range, the alkali to be used is not specifically limited, For example, a wide range, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, a chelating agent, and surfactant, can be used. Moreover, the temperature of the aqueous solution in a 1st washing process is 20-90 degreeC, Preferably it is 40-60 degreeC.

  Subsequently, a second cleaning process is performed in which electrolysis is performed in an aqueous solution using the conductive substrate as an electrode, and washing with water is repeated several times. As a result, a gas (hydrogen or oxygen) is generated on the surface of the conductive substrate, and the contamination of the surface of the conductive substrate is further efficiently removed by the redox action of the gas and the physical action of the gas bubbles. .

  Here, the pH of the aqueous solution in the second cleaning treatment is preferably 0.01 or more, and more preferably, the treatment is performed with an alkali having a pH of 8 or more. Further specifying the pH range, the upper limit is 13.8, more preferably 13.5, while the lower limit of the pH is 8.5, more preferably 9. If the pH is less than 0.01 or the pH exceeds 13.8, the surface of the conductive substrate is excessively roughened or deteriorated.

  In addition, as long as it becomes the said pH range, the alkali to be used is not specifically limited, For example, a wide range, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, a chelating agent, and surfactant, can be used.

The electrolysis conditions are as follows: liquid temperature 20 to 80 ° C., preferably 30 to 60 ° C., current density 0.1 to 20 A / dm ² , preferably 1 to 10 A / dm ² , electrolysis time 0.1 to 5 Minutes, preferably 0.5 to 2 minutes. In addition, the conductive substrate may be either an anode or a cathode, and a so-called PR method or a high-speed inversion method that sequentially switches between the anode and the cathode during the processing can be employed. In particular, it is preferable to use a conductive substrate as a cathode because the oxide on the surface of the conductive substrate can be removed by reduction.

  Thereafter, the conductive substrate is immersed in a bath containing an acid such as sulfuric acid, hydrochloric acid, ammonium persulfate, hydrogen peroxide, etc., and acid treatment (activation treatment) is performed by causing the acid to act on the surface of the conductive substrate. Can be performed.

  Here, the pH of the acid is preferably less than 7, more preferably the upper limit of pH is 3, more preferably 2, while the lower limit of pH is 0.001, more preferably 0.1. . If the pH exceeds 7, sufficient activation treatment cannot be performed, and if the pH is less than 0.001, the surface of the conductive substrate is excessively roughened or deteriorated.

  In addition, the immersion time for immersing the conductive substrate in the acid-containing tank is preferably 0.1 to 10 minutes, more preferably the upper limit is 5 minutes, more preferably 3 minutes, The lower limit is 0.5 minutes, more preferably 1 minute. When the immersion time is less than 0.1 minutes, sufficient activation treatment cannot be performed, and when the immersion time exceeds 10 minutes, the conductor surface is excessively roughened or deteriorated. Moreover, the liquid temperature of the said immersion tank is 10-90 degreeC, Preferably it is 20-50 degreeC.

  In the case where the conductive substrate is a polymer film in which a copper layer made of copper or a copper alloy is formed in a circuit shape, the acid cleaning can be performed without performing the first and second cleaning treatments as described above. It is also possible to perform only the treatment by acid (acid treatment). This is to prevent the polymer film from being deteriorated by the washing treatment with alkali. In this case as well, the same conditions as described above can be adopted for the treatment with acid (acid treatment).

  Thus, by performing a pretreatment on the surface of the conductive substrate, the surface coating layer can be formed on the conductive substrate with uniform and strong adhesion without the occurrence of pinholes.

<Underlayer formation process>
In the method for manufacturing a terminal of the present invention, the underlayer forming step can be performed following the pretreatment step. Such a base layer forming step is performed when the conductive substrate is made of a material that is difficult to adhere to the surface coating layer, for example, when the conductive substrate is SUS or iron, or when the conductive substrate is made of brass and contained in the brass. This is effective when Zn diffuses into the surface coating layer and hinders solderability.

  In the present invention, even when the underlayer is formed in this way, it is assumed that the Sn layer is formed on the entire surface or part of the conductive substrate. As long as it is made of metal, the underlayer can be understood as the conductive substrate itself.

  Such an underlayer can be formed by electroplating Ni with a thickness of 0.01 to 20 μm, preferably 0.5 to 5 μm, for example, when the conductive substrate is SUS. When the conductive substrate is brass, the base layer can be formed by electroplating Ni or Cu with the same thickness as described above.

  As described above, when the base layer is formed of Ni, a Watt bath or a sulfamic acid bath can be used. On the other hand, when the underlayer is formed of Cu, a copper cyanide bath or a copper sulfate bath can be used.

<Step of forming Sn layer>
A conductive substrate (a conductive substrate after the above pretreatment step and / or underlayer forming step as described above is performed) is immersed in a plating bath and electroplated with Sn as an anode. Thus, the Sn layer can be formed on the entire surface or part of the conductive substrate.

  Here, as the conditions for the electroplating, the composition of the plating solution may be any conventionally known composition such as an organic acid bath, a fluorination bath, or an alkali bath. For example, in the case of an organic acid bath, the metal Sn is 1 to 90 g / l, preferably 30 to 60 g / l, the organic acid is 50 to 250 g / l, preferably 70 to 130 g / l, and other small amounts of additives (however, secondary) And a composition containing 1 to 100 cc / l, preferably 30 to 50 cc / l, which is composed of only the primary additive without containing the system additive.

The temperature of the plating solution can be 10 to 70 ° C., preferably 15 to 50 ° C., and the current density is 0.1 to 40 A / dm ² , preferably 0.5 to 30 A / dm ^2. Can do.

  When electroplating is performed using the conductive substrate as a cathode and Sn as an anode, an Sn layer can be formed on the entire surface or part of the conductive substrate. In this case, since Sn is successively supplied from the anode in the plating solution, the Sn concentration in the plating solution hardly changes and is kept constant.

<Step of forming Sn alloy layer>
The Sn layer is formed by immersing the conductive substrate on which the Sn layer is formed in a plating bath, and electroplating by using a metal other than Sn and Sn alloy as an anode and supplying each element constituting the Sn alloy as a salt. An Sn alloy layer can be formed thereon. The terminal of the present invention is completed by executing this step.

  As described above, this step is not limited to this. For example, Sn is used as an anode and an alloy constituent element other than Sn is supplied as a salt, or an Sn alloy is used as an anode. It is also possible to adopt a method to do this.

  Here, as a condition for electroplating when a metal other than Sn and Sn alloy is used as an anode, the composition of the plating solution is as follows: Sn—Ag binary alloy, Sn—Ag—Cu ternary alloy and Sn—Ag— In any case of the Cu—Bi quaternary alloy, it contains a salt of each element constituting the Sn alloy, and any of an organic acid bath, a fluoride bath, an alkali bath, and the like can be used. Among these, it is particularly preferable to use an organic acid bath.

  Thus, when using an organic acid bath, the salt of each element which comprises Sn alloy turns into a salt of this each element and organic acid. The expression salt used in the present invention includes the case where it is ionized in an aqueous solution and exists in the form of ions.

  More specifically, regarding the composition of such a plating solution, the composition of the Sn—Ag binary alloy plating solution is 10 to 90 g / l of metal Sn, preferably 30 to 60 g / l, and 0. 1-20 g / l, preferably 1-5 g / l, organic acid 20-200 g / l, preferably 80-130 g / l, chelating agent 1-50 g / l, preferably 10-30 g / l, other small amounts A composition containing 1 to 100 cc / l, preferably 30 to 50 cc / l of additives (may contain a small amount of secondary additives in addition to the primary additives) can be mentioned.

  Moreover, as a composition of the plating solution of Sn-Ag-Cu ternary alloy, metal Sn is 10 to 90 g / l, preferably 30 to 60 g / l, metal Ag is 0.1 to 20 g / l, preferably 1 to 5 g / l, metal Cu 0.1-20 g / l, preferably 1-5 g / l, organic acid 20-200 g / l, preferably 80-130 g / l, chelating agent 1-50 g / l, preferably 10-30 g / l and other small amount of additive (may contain a small amount of secondary additive in addition to primary additive) 1-100 cc / l, preferably 30-50 cc / l Can be mentioned.

  Moreover, as a composition of the plating solution of Sn-Ag-Cu-Bi quaternary alloy, metal Sn is 10 to 90 g / l, preferably 30 to 60 g / l, metal Ag is 0.1 to 20 g / l, preferably 1-5 g / l, metal Cu 0.1-20 g / l, preferably 1-5 g / l, metal Bi 0.1-20 g / l, preferably 1-5 g / l, organic acid 20-200 g / L, preferably 80 to 130 g / l, chelating agent 1 to 50 g / l, preferably 10 to 30 g / l, and other small amounts of additives (in addition to primary additives, secondary additives are included in small amounts) May be included) in a composition containing 1 to 100 cc / l, preferably 30 to 50 cc / l.

The temperature of each plating solution can be 10 to 60 ° C., preferably 20 to 40 ° C., and the current density is 0.1 to 40 A / dm ² , preferably 0.5 to 30 A / dm ² . can do.

  Further, as described above, each plating solution preferably contains a chelating agent. If this chelating agent is not used, metals other than Sn, such as Ag, Cu and Bi, separate from the plating solution, and a Sn alloy layer having a desired alloy ratio is formed by electroplating. This is because it becomes difficult.

  In addition, as such a chelating agent, it is preferable to use at least two or more Sn—Ag—Cu ternary alloy plating solution or Sn—Ag—Cu—Bi quaternary alloy plating solution. This is because the types of chelating agents suitable for preventing the separation and precipitation of Ag, Cu, and Bi metals are different from each other.

  That is, for example, an inorganic chelating agent is a suitable chelating agent that prevents the separation and precipitation of Ag and Bi, while an organic chelating agent is a suitable chelating agent that prevents the separation and precipitation of Cu. However, some organic chelating agents effectively prevent the separation and precipitation of Ag and Bi (particularly 4- (2-pyridylazo) resorcin effectively prevents the separation and precipitation of Bi). Some agents effectively prevent Cu separation and precipitation.

  Some of these metals effectively prevent the separation and precipitation of two kinds of metals by a single chelating agent (in this case, the two kinds of metals tend to be a combination of Ag and Bi). A single chelating agent that simultaneously prevents the separation and precipitation of three kinds of metals, Cu and Bi, is not yet known. Therefore, it is necessary to use at least two chelating agents as a result, and it is particularly preferable to use an inorganic chelating agent and an organic chelating agent in combination.

Examples of such inorganic chelating agents include condensed phosphate chelating agents, aluminum salt chelating agents, manganese salt chelating agents, magnesium salt chelating agents, metal fluoro complex chelating agents (for example, (TiF ²⁻ )). OH, and the like can be given (SiF ^2-) OH, etc.).

  Examples of organic chelating agents include nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, dipivaloylmethanate, lauryldiacetic acid, 4- (2-pyridylazo) resorcin, and methylenediamines. Examples include porphyrins and phthalocyanines.

  In this step, electroplating can be performed by using the conductive substrate on which the Sn layer is formed as a cathode and using a metal other than Sn and an Sn alloy as an anode. Thereby, an Sn alloy layer is formed on the Sn layer, and the terminal of the present invention is obtained. Unlike the case where the Sn layer is formed, Sn is not supplied from the anode in the plating solution. Therefore, the salt of each element constituting the Sn alloy as described above is sequentially supplied to the plating solution. As a result, the salt concentration of each element constituting the Sn alloy in the plating solution is kept constant.

  The salt of each element constituting the Sn alloy as described above is more expensive than Sn as an anode used for forming the Sn layer. As described above, in the present invention, the surface coating layer is used as the Sn alloy layer. And the Sn layer, the amount of salt used is small compared with the case where the surface coating layer is formed only by the Sn alloy layer, and the cost of the terminal can be reduced. .

  Here, the metal other than Sn and the Sn alloy is used as the anode in order to prevent a so-called substitution phenomenon in which a metal other than Sn such as Ag, Cu, Bi, etc. is deposited on the anode surface.

  Examples of such an anode include Pt, Ir, Ru, Rh, or those obtained by coating the surface of an electrode made of Ti with one or more of these. Among these, the use of an electrode made of Ti coated on the surface of Pt can effectively prevent the above-described substitution phenomenon, and can be a particularly suitable example.

  The plating apparatus used for carrying out the above electroplating is not particularly limited. For example, as described above, by using any of the barrel plating apparatus, the hook plating apparatus, or the continuous plating apparatus. It is preferable to implement. By using these devices, the terminal of the present invention can be manufactured very efficiently.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
First, after tape-shaped copper rolled into a thickness of 0.3 mm and a width of 30 mm as a conductive substrate is pressed into the shape of a connector and a continuous connector terminal is cut to a length of 100 m, I wound it on a reel. And this reel was set to the delivery shaft of a continuous plating apparatus.

  Next, the conductive substrate is immersed in the immersion bath of the continuous plating apparatus filled with an aqueous solution containing sodium hydroxide having a liquid temperature of 48 ° C. (Eglace 30 (Okuno Pharmaceutical Co., Ltd.), 50 g / l used, pH 12.5). The first cleaning treatment was performed by continuously immersing the material for 1 minute. Thereafter, washing was performed several times.

Subsequently, in the electrolytic bath in which the pH of the continuous plating apparatus was alkaline (NC lastol (made by Okuno Pharmaceutical Co., Ltd.) as a sodium hydroxide aqueous solution was used at 100 g / l, pH 13.2), the first cleaning treatment was performed. A second washing process was performed by conducting electrolysis for 1 minute under the conditions of a liquid temperature of 50 ° C. and a current density of 5 A / dm ^{2 using} the conductive substrate as a cathode, and then washing with water five times was repeated.

  Next, the conductive substrate thus cleaned is immersed in an activation bath at 30 ° C. and filled with sulfuric acid having a pH of 0.5 for 1 minute, so that an acid acts on the surface of the conductive substrate. The acid treatment with the acid to be performed was performed. Thereafter, washing with water was repeated three times.

Next, a step of forming a Sn layer made of Sn by electroplating was performed on the conductive substrate subjected to the above treatment. That is, the conductive substrate subjected to the above treatment is immersed in the plating bath of the continuous plating apparatus, the conductive substrate is used as a cathode and Sn is used as the anode, and a plating solution ( Filled with 110 g / l organic acid (Metas AM, manufactured by Yuken Kogyo), Sn 60 g / l, additive (SBS-M, manufactured by Yuken Kogyo Co., Ltd.) 30 cc / l, liquid temperature 35 ° C., pH 0.5, current An Sn layer was formed on the conductive substrate by electroplating under conditions of a density of 4 A / dm ² for 2 minutes.

Subsequently, the Sn base layer formed of the Sn-Ag binary alloy is formed on the Sn layer by continuously immersing the conductive substrate on which the Sn layer is formed as described above in a plating bath of the continuous plating apparatus and performing electroplating. A forming step was performed. That is, a conductive substrate on which an Sn layer is formed is used as a cathode, a surface of an electrode made of Ti as an anode is coated with Pt, and a plating solution of Sn—Ag binary alloy is used in the plating bath of the above continuous plating apparatus. (Organic acid (Metas AM, Yuken Kogyo) 110 g / l, Sn 60 g / l, Ag 3 g / l, additive (FCM-C, manufactured by FCM) 30 cc / l) was charged, and the liquid temperature was 35 ° C., pH 0. 5. An Sn alloy layer made of a Sn—Ag binary alloy was formed by electroplating under conditions of a current density of 4 A / dm ² for 0.5 minutes. Then, after performing water washing 4 times, after draining with air, the terminal of this invention was obtained by drying for 2 minutes with a 70 degreeC hot air.

  The terminal thus obtained was sampled at a point 10 m and a point 90 m from the end, the cross section was cut using a FIB apparatus, and the thickness was measured. As a result, the thickness of the Sn layer was 4 μm. The thickness of the Sn alloy layer made of the Ag binary alloy was 1 μm. Moreover, the Sn alloy layer is an aggregate of fine crystal particles as shown in FIG. 1 and is extremely uniform.

  Moreover, when the alloy ratio of the Sn alloy layer was measured using EPMA (Electron Beam Microanalyzer, manufactured by JEOL Ltd.), the content ratio was Sn 96.5% by mass and Ag 3.5% by mass. Further, the melting point of this Sn alloy layer was 221 ° C., which showed good solderability.

<Example 2>
First, after tape-shaped phosphor bronze rolled to a thickness of 0.3 mm and a width of 30 mm as a conductive substrate is pressed into a connector shape, and a continuous connector terminal shape is cut to a length of 100 m And wound on a reel. And this reel was set to the delivery shaft of a continuous plating apparatus.

  Next, the conductive substrate is immersed in the immersion bath of the continuous plating apparatus filled with an aqueous solution containing sodium hydroxide having a liquid temperature of 48 ° C. (Eglace 30 (Okuno Pharmaceutical Co., Ltd.), 50 g / l used, pH 12.5). The first cleaning treatment was performed by continuously immersing the material for 1 minute. Thereafter, washing was performed several times.

Subsequently, in the electrolytic bath in which the pH of the continuous plating apparatus was alkaline (NC lastol (made by Okuno Pharmaceutical Co., Ltd.) as a sodium hydroxide aqueous solution was used at 100 g / l, pH 13.2), the first cleaning treatment was performed. A second washing process was performed by conducting electrolysis for 1 minute under the conditions of a liquid temperature of 50 ° C. and a current density of 5 A / dm ^{2 using} the conductive substrate as a cathode, and then washing with water five times was repeated.

  Next, the conductive substrate thus cleaned is immersed in an activation bath at 30 ° C. and filled with sulfuric acid having a pH of 0.5 for 1 minute, so that an acid acts on the surface of the conductive substrate. The acid treatment with the acid to be performed was performed. Thereafter, washing with water was repeated three times.

Next, a base layer forming step for forming a base layer made of Ni was performed on the conductive substrate that had undergone the above treatment. That is, a Ni plating solution (containing nickel sulfate 240 g / l, nickel chloride 45 g / l, boric acid 40 g / l) was filled in the plating bath of the above continuous plating apparatus, the solution temperature 55 ° C., pH 3.8, current density 4 A / A base layer made of Ni was formed by electroplating under the condition of dm ² for 5 minutes. Thereafter, washing with water was performed three times.

Then, the step which forms the Sn layer which consists of Sn by electroplating with respect to the electroconductive base which passed through said process was implemented. That is, the conductive substrate subjected to the above treatment is immersed in the plating bath of the continuous plating apparatus, the conductive substrate is used as a cathode and Sn is used as the anode, and a plating solution ( Filled with 110 g / l organic acid (Metas AM, manufactured by Yuken Kogyo), Sn 60 g / l, additive (SBS-M, manufactured by Yuken Kogyo Co., Ltd.) 30 cc / l, liquid temperature 35 ° C., pH 0.5, current An Sn layer was formed on the conductive substrate on which the underlayer was formed by electroplating under conditions of a density of 4 A / dm ² for 2 minutes.

Next, the Sn alloy layer made of Sn—Ag—Cu ternary alloy is formed on the Sn layer by subsequently immersing the conductive substrate on which the Sn layer is formed as described above in a plating bath of the continuous plating apparatus and performing electroplating. The step of forming was carried out. That is, a conductive substrate on which an Sn layer is formed is used as a cathode, and the surface of an electrode made of Ti as an anode is coated with Pt, and the Sn-Ag-Cu ternary alloy is used in the plating bath of the above continuous plating apparatus. Plating solution (Organic acid (Metas AM, Yuken Kogyo) 110 g / l, Sn 60 g / l, Ag 3 g / l, Cu 2 g / l, inorganic chelating agent (for preventing separation and precipitation of Ag, FCM-A, manufactured by FCM) 15 g / L, filled with organic chelating agent (for Cu separation and precipitation prevention, FCM-B, manufactured by FCM) 10 g / l, additive (FCM-C, manufactured by FCM) 30 cc / l), and liquid temperature 35 An Sn alloy layer made of Sn—Ag—Cu ternary alloy was formed by electroplating for 0.5 minutes under the conditions of ° C., pH 0.5, and current density 4 A / dm ² . Then, after performing water washing 4 times, after draining with air, the terminal of this invention was obtained by drying for 2 minutes with a 70 degreeC hot air.

  The terminal obtained in this way was sampled at 10 m and 90 m from the end, and when the cross section was cut using a FIB apparatus and the thickness was measured, the thickness of the underlayer made of Ni was 1 μm. The thickness of the Sn layer was 4 μm, and the thickness of the Sn alloy layer made of Sn—Ag—Cu ternary alloy was 1 μm. Moreover, the Sn alloy layer is an aggregate of fine crystal particles as shown in FIG. 1 and is extremely uniform.

  Moreover, when the alloy ratio of the Sn alloy layer was measured using EPMA (Electron Beam Microanalyzer, manufactured by JEOL Ltd.), the content ratio was 94% by mass of Sn, 5% by mass of Ag, and 1% by mass of Cu. Further, the melting point of this Sn alloy layer was 216 ° C., which showed good solderability.

<Example 3>
First, after tape-shaped iron rolled into a thickness of 0.3 mm and a width of 30 mm as a conductive substrate is pressed into a connector shape, and a continuous connector terminal shape is cut into a length of 100 m, I wound it on a reel. And this reel was set to the delivery shaft of a continuous plating apparatus.

  Next, the conductive substrate is immersed in the immersion bath of the continuous plating apparatus filled with an aqueous solution containing sodium hydroxide having a liquid temperature of 48 ° C. (Eglace 30 (Okuno Pharmaceutical Co., Ltd.), 50 g / l used, pH 12.5). The first cleaning treatment was performed by continuously immersing the material for 1 minute. Thereafter, washing was performed several times.

Subsequently, in the electrolytic bath in which the pH of the continuous plating apparatus was alkaline (NC lastol (made by Okuno Pharmaceutical Co., Ltd.) as a sodium hydroxide aqueous solution was used at 100 g / l, pH 13.2), the first cleaning treatment was performed. A second washing process was performed by conducting electrolysis for 1 minute under the conditions of a liquid temperature of 50 ° C. and a current density of 5 A / dm ^{2 using} the conductive substrate as a cathode, and then washing with water five times was repeated.

  Next, the conductive substrate thus cleaned is immersed in an activation bath at 30 ° C. and filled with sulfuric acid having a pH of 0.5 for 1 minute, so that an acid acts on the surface of the conductive substrate. The acid treatment with the acid to be performed was performed. Thereafter, washing with water was repeated three times.

Next, the base layer formation process which forms the base layer which consists of Cu with respect to the electroconductive base | substrate which passed through the said process was implemented. That is, a Cu plating solution (made of copper cyanide 70 g / l, sodium cyanide 20 g / l) is filled in the plating bath of the above continuous plating apparatus, the solution temperature is 50 ° C., and the current density is 2.5 A / dm ² . An underlayer made of Cu was formed by electroplating under conditions for 1 minute. Thereafter, washing with water was performed three times.

Then, the step which forms the Sn layer which consists of Sn by electroplating with respect to the electroconductive base which passed through said process was implemented. That is, the conductive substrate subjected to the above treatment is immersed in the plating bath of the continuous plating apparatus, the conductive substrate is used as a cathode and Sn is used as the anode, and a plating solution ( Filled with 110 g / l organic acid (Metas AM, manufactured by Yuken Kogyo), Sn 60 g / l, additive (SBS-M, manufactured by Yuken Kogyo Co., Ltd.) 30 cc / l, liquid temperature 35 ° C., pH 0.5, current An Sn layer was formed on the conductive substrate on which the underlayer was formed by electroplating under conditions of a density of 4 A / dm ² for 2 minutes.

Next, the conductive substrate on which the Sn layer is formed as described above is subsequently immersed in a plating bath of the continuous plating apparatus and electroplated to form Sn-Ag-Cu-Bi quaternary alloy on the Sn layer. A step of forming an alloy layer was performed. That is, a conductive substrate on which an Sn layer is formed is used as a cathode, a surface of an electrode made of Ti as an anode is coated with Pt, and Sn—Ag—Cu—Bi quaternary is used as a plating bath of the above continuous plating apparatus. Alloy plating solution (Organic acid (Metas AM, Yuken Kogyo) 110 g / l, Sn 60 g / l, Ag 3 g / l, Cu 2 g / l, Bi 1 g / l, inorganic chelating agent (for preventing precipitation of Ag and Bi, FCM) -A, manufactured by FCM) 15 g / l, organic chelating agent (for preventing Cu separation and precipitation, FCM-B, manufactured by FCM) 10 g / l, additive (FCM-C, manufactured by FCM) 30 cc / l ), And electroplating for 0.5 minutes under conditions of a liquid temperature of 35 ° C., pH 0.5, and current density of 4 A / dm ² , thereby forming an Sn alloy layer made of Sn—Ag—Cu—Bi quaternary alloy Formed. Then, after performing water washing 4 times, after draining with air, the terminal of this invention was obtained by drying for 2 minutes with a 70 degreeC hot air.

  The terminal thus obtained was sampled at 10 m and 90 m from the end, and when the cross section was cut using a FIB apparatus and the thickness was measured, the thickness of the underlying layer made of Cu was 1 μm. The thickness of the Sn layer was 4 μm, and the thickness of the Sn alloy layer made of Sn—Ag—Cu—Bi quaternary alloy was 1 μm. Moreover, the Sn alloy layer is an aggregate of fine crystal particles as shown in FIG. 1 and is extremely uniform.

  Moreover, when the alloy ratio of the Sn alloy layer was measured using EPMA (Electron Beam Microanalyzer, manufactured by JEOL Ltd.), it was a content ratio of Sn 93% by mass, Ag 5% by mass, Cu 1% by mass, and Bi1% by mass. . Moreover, the melting point of this Sn alloy layer was 212.5 ° C., indicating good solderability.

<Comparative Example 1>
In Example 1, a terminal was obtained in the same manner as in Example 1 except that the thickness of the Sn layer was 5 μm and the Sn alloy layer made of the Sn—Ag binary alloy was not formed.

<Comparative example 2>
In Example 1, a terminal was obtained in the same manner as in Example 1 except that the Sn layer was not formed and the thickness of the Sn alloy layer made of the Sn—Ag binary alloy was 5 μm.

<Comparative Example 3>
In Example 2, a terminal was obtained in the same manner as Example 2 except that the Sn layer was not formed and the thickness of the Sn alloy layer made of the Sn—Ag—Cu ternary alloy was 5 μm. .

<Comparative example 4>
In Example 3, except that the Sn layer is not formed and the thickness of the Sn alloy layer made of Sn—Ag—Cu—Bi quaternary alloy is set to 5 μm, the terminals are formed in the same manner as in Example 3. Obtained.

<Solder wettability test>
A solder wettability test was performed using the terminal of each example obtained above and the terminal of each comparative example.

  Specifically, each terminal having the same shape is immersed in a molten Sn—Ag—Cu solder bath heated to 250 ° C. until the terminal surface melts and begins to get wet with the solder in the solder bath. This was done by measuring the time. The shorter the time, the better the solderability. The results are shown in Table 1 below.

<Whisker generation test>
A whisker generation test was conducted using the terminal of each example obtained above and the terminal of each comparative example.

  Specifically, each terminal was held in a high-temperature and high-humidity tank (60 ° C., humidity 90%) for 168 hours, and then the presence or absence of whisker generation was confirmed. The results are shown in Table 1 below.

<Cost comparison>
When the cost of the terminal of Comparative Example 1 was 100 (index), the cost of each terminal was shown as a relative index. The larger the index, the more disadvantageous the cost. The comparison is shown in Table 1 below.

  As is apparent from Table 1, the terminal of Comparative Example 1 in which the Sn alloy layer was not formed was advantageous in terms of cost, but was poor in solder wettability and accompanied by whisker generation. On the other hand, the comparative examples 2 to 4 showed the same performance with respect to the solder wettability and the presence or absence of whisker compared with those of the examples 1 to 3, but the cost was extremely inferior. It was a thing. From these results, it is understood that the terminal of each example of the present invention achieves both excellent performance (coexistence of whisker generation and good solderability) and cost.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a microscope picture of the cross section of the terminal which formed Sn-Ag-Cu ternary alloy as a Sn alloy layer on Sn layer. It is a microscope picture of the cross section of the terminal in which only the Sn layer was formed.

The terminal of the present invention is formed by forming a Sn layer on the entire surface or part of a conductive substrate, and forming an Sn alloy layer on the Sn layer, and the Sn layer is formed by electroplating. Sn—Ag—Cu ternary alloy having a thickness of 0.1 to 20 μm and a melting point of 230 ° C. or less. It is characterized by being a layer consisting of

The Sn layer can be formed by immersing the conductive substrate in a plating bath and electroplating using Sn as an anode, and the Sn alloy layer is formed by forming the Sn layer. was immersed in a plating bath containing a chelating agent, it shall be formed by electroplating by metals other than Sn and Sn alloy supplying each element constituting the Sn alloy with an anode as a salt it can.

Upper Symbol Sn-Ag-Cu ternary alloy, Ag is 0.1 to 20 mass%, Cu is 0.1 to 20 mass%, can be composed of a content ratio of the residual is Sn.

The terminal manufacturing method of the present invention is a terminal manufacturing method in which an Sn layer is formed on the whole or part of a conductive substrate, and an Sn alloy layer is formed on the Sn layer. A step of forming an Sn layer on the whole or part of the conductive substrate by immersing in a plating bath and electroplating using Sn as an anode, and the conductive substrate on which the Sn layer is formed in a plating bath containing a chelating agent Dipping and using a metal other than Sn and Sn alloy as an anode and forming an Sn alloy layer on the Sn layer by electroplating by supplying each element constituting the Sn alloy as a salt. be able to.

<Sn alloy layer>
The Sn alloy layer of the present invention is formed on the above Sn layer, and is Sn-Ag-Cu ternary having a thickness of 0.1 to 20 μm and a melting point of 230 ° C. or less formed by electroplating. It is a layer made of an alloy . These Sn alloys are constituted by the content ratios (alloy ratios) described later only with the respective alloy constituent elements except for the inclusion of inevitable impurities.

Here, as a condition for electroplating when a metal other than Sn and the Sn alloy is used as an anode, the composition of the plating solution first contains a salt of each element constituting the Sn alloy. Either a chemical bath or an alkali bath can be used. Among these, it is particularly preferable to use an organic acid bath.

Further, as described above, each plating solution preferably contains a chelating agent. If this chelating agent is not used, metals other than Sn, such as Ag and Cu, separate from the plating solution, and it is difficult to form a Sn alloy layer having a desired alloy ratio by electroplating. Because it becomes.

In addition, such chelating agents in the plating solution Sn-Ag-Cu ternary alloy, it is preferred to use at least 2 or more. This is because the types of chelating agents suitable for preventing the separation and precipitation of Ag and Cu metals are different from each other.

That is, for example, an inorganic chelating agent is a suitable chelating agent that prevents the separation and precipitation of Ag , while an organic chelating agent is a suitable chelating agent that prevents the separation and precipitation of Cu. However, there is also an organic chelating agent Ri mower as to effectively prevent the separation precipitation of Ag, also be an inorganic chelating agent is also intended to effectively prevent the separation deposition of Cu.

Therefore, consequently it than it is necessary to use at least two or more chelating agents, it is preferable to particularly used together with the inorganic chelating agent and the organic chelating agent.

Here, the reason why the metal other than Sn and Sn alloy is used as the anode is to prevent a so-called substitution phenomenon in which a metal other than Sn, such as Ag and Cu , is deposited on the surface of the anode.

<Reference Example 1>
First, after tape-shaped copper rolled into a thickness of 0.3 mm and a width of 30 mm as a conductive substrate is pressed into the shape of a connector and a continuous connector terminal is cut to a length of 100 m, I wound it on a reel. And this reel was set to the delivery shaft of a continuous plating apparatus.

Subsequently, the Sn base layer formed of the Sn-Ag binary alloy is formed on the Sn layer by continuously immersing the conductive substrate on which the Sn layer is formed as described above in a plating bath of the continuous plating apparatus and performing electroplating. A forming step was performed. That is, a conductive substrate on which an Sn layer is formed is used as a cathode, a surface of an electrode made of Ti as an anode is coated with Pt, and a plating solution of Sn—Ag binary alloy is used in the plating bath of the above continuous plating apparatus. (Organic acid (Metas AM, Yuken Kogyo) 110 g / l, Sn 60 g / l, Ag 3 g / l, additive (FCM-C, manufactured by FCM) 30 cc / l) was charged, and the liquid temperature was 35 ° C., pH 0. 5. An Sn alloy layer made of a Sn—Ag binary alloy was formed by electroplating under conditions of a current density of 4 A / dm ² for 0.5 minutes. Then, after performing 4 times with water, after draining by the air, to obtain a Litan child by the drying for 2 minutes with hot air at 70 ° C..

<Example 1>
First, after tape-shaped phosphor bronze rolled to a thickness of 0.3 mm and a width of 30 mm as a conductive substrate is pressed into a connector shape, and a continuous connector terminal shape is cut to a length of 100 m And wound on a reel. And this reel was set to the delivery shaft of a continuous plating apparatus.

<Reference Example 2>
First, after tape-shaped iron rolled into a thickness of 0.3 mm and a width of 30 mm as a conductive substrate is pressed into a connector shape, and a continuous connector terminal shape is cut into a length of 100 m, I wound it on a reel. And this reel was set to the delivery shaft of a continuous plating apparatus.

Next, the conductive substrate on which the Sn layer is formed as described above is subsequently immersed in a plating bath of the continuous plating apparatus and electroplated to form Sn-Ag-Cu-Bi quaternary alloy on the Sn layer. A step of forming an alloy layer was performed. That is, a conductive substrate on which an Sn layer is formed is used as a cathode, a surface of an electrode made of Ti as an anode is coated with Pt, and Sn—Ag—Cu—Bi quaternary is used as a plating bath of the above continuous plating apparatus. Alloy plating solution (Organic acid (Metas AM, Yuken Kogyo) 110 g / l, Sn 60 g / l, Ag 3 g / l, Cu 2 g / l, Bi 1 g / l, inorganic chelating agent (for preventing precipitation of Ag and Bi, FCM) -A, manufactured by FCM) 15 g / l, organic chelating agent (for preventing Cu separation and precipitation, FCM-B, manufactured by FCM) 10 g / l, additive (FCM-C, manufactured by FCM) 30 cc / l ), And electroplating for 0.5 minutes under conditions of a liquid temperature of 35 ° C., pH 0.5, and current density of 4 A / dm ² , thereby forming an Sn alloy layer made of Sn—Ag—Cu—Bi quaternary alloy Formed. Then, after performing 4 times with water, after draining by the air, to obtain a Litan child by the drying for 2 minutes with hot air at 70 ° C..

<Comparative Example 1>
In Reference Example 1 , terminals were obtained in the same manner as in Reference Example 1 except that the thickness of the Sn layer was 5 μm and the Sn alloy layer made of the Sn—Ag binary alloy was not formed.

<Comparative example 2>
In Reference Example 1 , terminals were obtained in the same manner as Reference Example 1 except that the Sn layer was not formed and the thickness of the Sn alloy layer made of the Sn—Ag binary alloy was 5 μm.

<Comparative Example 3>
In Example 1 , a terminal was obtained in the same manner as Example 1 except that the Sn layer was not formed and that the thickness of the Sn alloy layer made of the Sn—Ag—Cu ternary alloy was 5 μm. .

<Comparative example 4>
In Reference Example 2 , except that the Sn layer is not formed and the thickness of the Sn alloy layer made of Sn—Ag—Cu—Bi quaternary alloy is set to 5 μm, all the other steps were performed in the same manner as in Reference Example 2. Obtained.

<Solder wettability test>
A solder wettability test was performed using the terminal of Example 1 obtained above and the terminal of each comparative example.

<Whisker generation test>
A whisker generation test was performed using the terminal of Example 1 obtained above and the terminal of each comparative example.

As is clear from Table 1, the terminal of Comparative Example 1 in which the Sn alloy layer was not formed was advantageous in terms of cost, but was poor in solder wettability and accompanied by whisker generation. In contrast, Comparative Examples 2 to 4 showed comparable performance with respect to solder wettability and the presence or absence of whiskers compared to Example 1 , but were extremely inferior in cost. there were. From these results, it is understood that the terminal of Example 1 of the present invention has both excellent performance (both prevention of whisker generation and good solderability) and cost.

Claims (15)

A terminal formed by forming a Sn layer on the entire surface or part of a conductive substrate and forming a Sn alloy layer on the Sn layer;
The Sn layer is a layer made of Sn having a thickness of 0.1 to 20 μm formed by electroplating,
The Sn alloy layer is any one of Sn-Ag binary alloy, Sn-Ag-Cu ternary alloy, or Sn-Ag-Cu-Bi quaternary alloy having a thickness of 0.1 to 20 μm formed by electroplating. A terminal characterized by being a layer comprising:   The Sn layer is formed by immersing the conductive substrate in a plating bath and electroplating using Sn as an anode, and the Sn alloy layer is formed by plating the conductive substrate on which the Sn layer is formed. 2. It is formed by dipping in a metal, electroplating by using a metal other than Sn and Sn alloy as an anode and supplying each element constituting the Sn alloy as a salt. Terminal.   2. The terminal according to claim 1, wherein the Sn—Ag binary alloy is configured with a content ratio in which Ag is 0.1 to 20 mass% and the balance is Sn.   The Sn-Ag-Cu ternary alloy is constituted by a content ratio in which Ag is 0.1 to 20 mass%, Cu is 0.1 to 20 mass%, and the balance is Sn. The listed terminal.   The Sn—Ag—Cu—Bi quaternary alloy has a content ratio in which Ag is 0.1 to 20 mass%, Cu is 0.1 to 20 mass%, Bi is 0.1 to 20 mass%, and the balance is Sn. The terminal according to claim 1, comprising:   2. The terminal according to claim 1, wherein the conductive substrate is a metal or a metal layer laminated on a surface of an insulating substrate.   The terminal according to claim 1, wherein an underlayer is formed between the conductive substrate and the Sn layer.   The terminal according to claim 1, wherein the electroplating is performed using any one of a barrel plating apparatus, a hook plating apparatus, and a continuous plating apparatus.   The terminal according to claim 1, wherein the Sn layer is matte plating, and the Sn alloy layer is matte plating or semi-gloss plating.   The terminal according to claim 1, wherein the terminal is one of a connector terminal, a relay terminal, a slide switch terminal, a bump, a solder terminal, or a flat cable terminal.   A component having the terminal according to claim 1.   The component according to claim 11, wherein the component is any one of a connector, a relay, a slide switch, a flat cable, a resistor, a capacitor, a coil, and a board.   A product comprising the terminal according to claim 1.   The product according to claim 13, wherein the product is one of a semiconductor product, an electrical product, an electronic product, a solar cell, or an automobile. A method for producing a terminal comprising: forming a Sn layer on the entire surface or part of a conductive substrate; and forming a Sn alloy layer on the Sn layer,
Immersing the conductive substrate in a plating bath and electroplating with Sn as an anode to form a Sn layer on the entire surface or part of the conductive substrate;
The Sn layer is formed by immersing the conductive substrate on which the Sn layer is formed in a plating bath, and electroplating by using a metal other than Sn and Sn alloy as an anode and supplying each element constituting the Sn alloy as a salt. Forming a Sn alloy layer thereon;
The manufacturing method of the terminal characterized by including.

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