JP2018168423A - Silver-plated copper substrate and method for manufacturing the same - Google Patents

Abstract

To provide a silver-plated copper substrate which is less likely to generate cracks on a silver gloss plating layer even during such a process as press restriction processing, and a method for manufacturing the same.MEANS FOR SOLVING THE PROBLEM: A silver-plated copper substrate 10 comprises: a copper strip material 12; a copper gloss plating layer 14 formed on the surface of the copper strip material 12; and a silver gloss plating layer 16 formed on the surface of the copper gloss plating layer 14. The copper gloss plating layer 14 is formed on the copper strip material 12 and the silver gloss plating layer 16 is formed on the copper gloss plating layer 14. The copper strip material 12 on which the copper gloss plating layer 14 and the silver gloss plating layer 16 are formed is made to pass through a non-oxidizing atmosphere so as to anneal the silver gloss plating layer 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silver-plated copper-based substrate having a bright silver-plated layer formed on a copper-based substrate and a method for producing the same.

  A silver-plated copper plate in which a silver-plated layer is formed on a copper plate is used as a switch terminal. The terminal of the switch is formed by press-drawing a silver-plated copper plate to form a convex portion at the contact portion of the terminal. Contact when the terminals are pressed by the convex portion can be improved. In order to improve the appearance, it can be considered that the silver plating layer is a bright silver plating layer. A bright silver plating layer is obtained by adding selenium as a brightening agent to silver.

  However, by adding a brightening agent to silver, the Vickers hardness of the bright silver plating layer becomes 110-130. Since the bright silver plating layer is hard, cracks may occur in the convex portions during press drawing. There is a possibility that the contact of the convex portion is deteriorated by the crack, and the electric resistance is increased. When cracks occur in the bright silver plating layer, the appearance is also deteriorated.

  The following Patent Document 1 discloses a movable contact material laminated on a conductive substrate in the order of an underlayer, an intermediate layer, and an outermost layer. The outermost layer uses an alloy of silver and selenium. Also, it is disclosed that cracking of the underlayer is prevented by using nickel or the like for the underlayer and defining the thickness of the underlayer.

  However, Patent Document 1 does not mention prevention of cracks on the outermost layer. Even if there is no crack in the underlayer, there is a possibility that a crack will occur in the outermost layer.

Japanese Patent Laying-Open No. 2015-117424 (paragraphs 0015 and 0023)

  An object of the present invention is to provide a silver-plated copper-based substrate and a method for producing the same, in which cracks are unlikely to occur in the bright silver plating layer when processing such as press drawing.

  The method for producing a silver-plated copper-based substrate of the present invention includes a step of preparing a copper-based substrate, a step of forming a bright copper-plated layer on the copper-based substrate, and forming a bright silver-plated layer on the bright copper-plated layer And a step of passing the non-oxidizing atmosphere through the copper base material on which the bright copper plating layer and the bright silver plating layer are formed and annealing the bright silver plating layer.

  The silver-plated copper-based substrate is formed on a copper-based substrate, a bright copper-plated layer formed on the copper-based substrate, and a bright copper-plated layer, and has a thickness of 6 to 8 μm and a Vickers hardness of 70. A bright silver plating layer of ~ 90 is provided.

  According to the present invention, the bright silver plating layer is annealed in a non-oxidizing atmosphere. Therefore, the Vickers hardness of the bright silver plating layer can be lowered. Even if a convex portion is formed on a silver-plated copper-based substrate by press drawing or the like, cracks are hardly generated in the bright silver-plated layer. Since annealing is performed in a non-oxidizing atmosphere, the copper base material is difficult to oxidize and the appearance of the copper base material is not easily damaged. Further, when the copper-based substrate is matte, the glossy silver-plated layer is adjacent to the matte copper-based substrate, so that the glossy silver-plated layer looks good.

It is a figure which shows a silver plating copper-type base material, (a) is a perspective view, (b) is an AA sectional view. It is a figure which shows the plating method of a silver plating copper-type base material. It is the figure which shows the manufacturing process of the silver plating copper base material, (a) is the figure where the masking tape is pasted to the copper base material, (b) forms the gloss copper plating layer in the part where there is no masking tape (C) is the figure which formed the glossy silver plating layer on the glossy copper plating layer. It is a figure which shows the annealing method of a silver plating copper-type base material. It is a perspective view which shows a silver plating copper-type base material, (a) is the figure which made the glossy silver plating layer square, (b) is the figure which made the glossy silver plating layer circular.

  The silver-plated copper base material of the present invention and the manufacturing method thereof will be described with reference to the drawings.

[Embodiment 1]
A silver-plated copper base material 10 shown in FIG. 1 includes a copper strip 12, a bright copper plating layer 14 formed on the surface of the copper strip 12, and a bright silver plating formed on the surface of the bright copper plating layer 14. Layer 16 is provided.

  The copper-based strip 12 that is a copper-based substrate is composed of a copper-based material made of pure copper or a copper alloy. Examples of copper alloys include phosphor bronze, aluminum bronze, brass, western white, beryllium copper, titanium copper, Corson alloy, white copper, and red copper.

  As the copper strip 12, for example, a strip (band-like body) having a width of about 80 mm and a thickness of about 0.8 mm is used. The copper strip 12 may be punched or the like to form a predetermined opening or notch in the copper strip 12.

  The bright copper plating layer 14 is formed on a part of the surface of the copper strip 12. In FIG. 1, the bright copper plating layer 14 is disposed on one surface 18 of the copper strip 14, but may be disposed on the other surface 20, or may be disposed on both the one surface 18 and the other surface 20. . The bright copper plating layer 14 has a narrower band shape than the copper strip 12, and its length direction is the same as the length direction of the copper strip 12. In FIG. 1, the number of the bright copper plating layers 14 is two, but the number of the bright copper plating layers 14 is not limited. The thickness of the bright copper plating layer 14 is 1 μm or less, for example, about 0.5 μm.

  The bright copper plating layer 14 is used for plating to produce chloride ions, SPS (bis-3-sulfopropyl-disulfide), mercaptobenzothiazolepropanesulfonic acid, JGB (Yarnus Green B), polyethylene glycol. It is a plating layer in which the surface of copper is smoothed by a system brightener. Specific examples of the brightener include “Capper Gream 125” manufactured by Rohm and Haas Electronic Materials Co., Ltd. The bright copper plating layer 14 is glossy.

  The bright silver plating layer 16 is overlaid on the bright copper plating layer 14 and has a strip shape like the bright copper plating layer 14. The bright silver plating layer 16 is a plating layer in which selenium or antimony is added to silver in order to give gloss.

  If there is no bright copper plating layer 14 below the bright silver plating layer 16, the bright silver plating layer 16 may be darkened. In the present application, the glossy silver plating layer 16 has a glossy silver color due to the glossy copper plating layer 14. When the surface 18 is viewed from above, the glossy silver plating layer 16 sandwiched between the matte copper-based strips 12 shines with gloss, so that the brightness of the glossy silver plating layer 16 is felt bright, and the silver-plated copper-based substrate 10 It looks better.

  As described later, the Vickers hardness (Hv) of the bright silver plating layer 16 is about 70 to 90 by annealing. For example, a normal bright silver plating layer to which selenium is added has a Vickers hardness of about 110 to 130, but in the present application, since the Vickers hardness of the bright silver plating layer 16 is lowered, a convex portion is formed by press drawing. However, cracks are unlikely to occur in the bright silver plating layer 16.

  The thickness of the bright silver plating layer 16 is about 1 to 10 μm, preferably about 6 to 8 μm. When the thickness is thinner than this, when the silver-plated copper-based substrate 10 is press-drawn to form convex portions, the bright silver-plated layer 16 becomes thin and the bright copper-plated layer 14 and the copper-based strip 12 appear on the surface. There is a fear. Further, if the thickness of the bright silver plating layer 16 becomes too thick, it takes time to manufacture and the cost is increased including the material cost.

  Next, the manufacturing method of the silver plating copper-type base material 10 is demonstrated. This application manufactures the silver plating copper-type base material 10 in order of following (1) to (8).

  (1) A copper strip 12 is prepared. As shown in FIG. 2, a copper strip 12 wound around a supply-side roll 22 to form a roll is prepared. The copper strip 12 is drawn from the supply-side roll 22, and the silver-plated copper base 10 is manufactured while the copper strip 12 is running. In the middle of running the copper strip 12, the running direction is changed or tension is applied by the roll 24 as necessary.

  In addition, before the following process, the copper-type strip material 12 is wash | cleaned as needed. Examples of cleaning methods include cathodic electrolytic degreasing and acid immersion. Cathodic electrolytic degreasing uses a sodium hydroxide aqueous solution, and acid immersion uses sulfuric acid.

  (2) In the copper strip 12, a plating resist is formed in a portion where the bright copper plating layer 14 and the bright silver plating layer 16 are not formed. For example, as shown in FIG. 3A, a masking tape 26 is used as a plating resist. As the masking tape 26, for example, a polyester resin or a fluorine resin is used. A silicon-based adhesive layer (not shown) is provided on the portion of the masking tape 26 where the copper strip 12 is attached. The thickness of the masking tape 26 is about 0.08 to 0.1 mm, for example.

  In FIG. 3A, three strip-shaped masking tapes 26 are attached to one surface 18 of the copper strip 12, and the masking tape 26 is attached to the entire other surface 20. The width and position of the masking tape 26 are changed depending on the shapes of the bright copper plating layer 14 and the bright silver plating layer 16 to be formed.

  The method of applying the masking tape 26 is as follows. As shown in FIG. 2, the masking tape 26 is wound around a supply-side roll 28 to form a roll. While pulling out the masking tape 26, the copper strip 12 and the masking tape 26 are synchronized. The affixing roll 30 rotates while synchronizing with the traveling speed of the copper strip 12 and the masking tape 26, and the copper strip 12 and the masking tape 26 are sandwiched by the affixing roll 30 so that the masking tape 26 is made of copper. Affixed to the surface of the system strip 12.

  (3) A bright copper plating layer 14 is formed on the copper strip 12 by electroplating (FIG. 3B). As shown in FIG. 2, the copper strip 12 is caused to travel in the plating solution 34 stored in the plating tank 32. The plating solution 34 may be a copper sulfate bath, which contains copper sulfate, sulfuric acid and chloride ions. Further, a brightener as described above is added to the plating solution 34.

  A cathode 36 is disposed upstream and downstream of the plating tank 32, and an anode 38 is disposed in the plating solution 34. The cathode 36 has a roll shape and rotates while contacting the copper strip 12. Even if the masking tape 26 is affixed to the copper strip 12, the thickness thereof is thin, and the cathode 36 comes into contact with the copper strip 12 due to blurring or fluttering while the copper strip 12 is running. The anode 38 is a plate-shaped electrode that is not in contact with the copper strip 12.

While the copper strip 12 is running, the copper strip 12 and the plating solution 34 are energized, and the bright copper plating layer 14 is electrodeposited on the portion of the copper strip 12 where the masking tape 26 is not present. An example of the current density at the time of electrodeposition is about 1 to 20 A / dm ² , but it is appropriately changed depending on the composition and temperature of the plating solution 34, the traveling speed of the copper-based strip 12, and the like.

  (4) A bright silver plating layer 16 is formed on the bright copper plating layer 14 by electroplating (FIG. 3C). As shown in FIG. 2, the copper strip 12 on which the bright copper plating layer 14 is formed is run in the plating solution 42 stored in the plating tank 40. The plating solution 42 is a plating solution mainly composed of silver potassium cyanide, and a brightener containing selenium or antimony is added to the plating solution 42.

A cathode 44 is disposed upstream and downstream of the plating tank 40, and an anode 46 is disposed in the plating solution 42. The cathode 44 has a roll shape and rotates while being in contact with the bright copper plating layer 14 on the copper strip 12. The anode 46 is a plate-like electrode that is not in contact with the copper strip 12 or the like. While running the copper strip 12 having the bright copper plating layer 14, the copper strip 12 and the plating solution 42 are energized to deposit the bright silver plating layer 16 on the bright copper plating layer 14. An example of the current density at the time of electrodeposition is about 0.5 to 1.5 A / dm ^2. However, the current density is appropriately changed depending on the composition and temperature of the plating solution 42, the running speed of the copper strip 12, and the like. When the brightener is selenium, the Vickers hardness (Hv) of the bright silver plating layer 14 at this stage is 110 to 130.

  (5) The masking tape 26 is peeled off from the copper strip 12. As shown in FIG. 2, the masking tape 26 travels along the stripping roll 48 and is wound around the winding-side roll 50. The copper strip 12 on which the bright copper plating layer 14 and the bright silver plating layer 16 are laminated moves straight, whereas the masking tape 26 moves away from the copper strip 12. Therefore, the masking tape 26 is peeled off from the copper strip 12.

  After peeling off the masking tape 26, the copper strip 12 on which the plating layers 14 and 16 are laminated is washed and dried as necessary. As a cleaning method, a method of immersing the copper-based strip material 12 in sodium triphosphate is exemplified.

  (6) The bright silver plating layer 14 and the bright silver plating layer 16 are passed through a non-oxidizing atmosphere and the bright silver plating layer 14 is annealed. As shown in FIG. 4, the annealing furnace 52 for annealing includes a heat-resistant annealing furnace main body 54, an inlet 56 of the copper strip 12 above the annealing furnace main body 54, and a copper below the annealing furnace main body 54. An outlet 58 of the system strip 12, a burner 60 provided in the annealing furnace main body 54, and a ventilation port 62 near the inlet 56 are provided. The annealing furnace body 54 has a cylindrical shape, and the inlet 56 and the outlet 58 are narrower than the annealing furnace body 54.

  The outlet 58 is in the coolant 66 stored in the water tank 64, and the inlet / outlet of air to the annealing furnace main body 54 is an inlet 56 and a ventilation port 62. By igniting the burner 60 in the annealing furnace main body 54, the inside of the annealing furnace main body 54 becomes a non-oxidizing atmosphere. For example, the oxygen concentration in the annealing furnace main body 54 is 100 ppm or less, preferably 50 ppm or less. The oxygen concentration is adjusted by intake / exhaust from the ventilation port 62. A pump may be used for the intake and exhaust.

  The copper strip 12 travels in the vertical direction from the inlet 56 to the outlet 58. The time for the copper-based strip 12 to reach from the inlet 56 to the outlet 58 is several seconds to several tens of seconds. During this time, the surface of the bright silver plating layer 14 is set to 500 to 700 ° C., and the bright silver plating layer 14 is annealed. The Vickers hardness (Hv) of the bright silver plating layer 14 is set to 70 to 90 by annealing. A burner 60 may be disposed at a position facing the bright silver plating layer 14 so that the bright silver plating layer 14 is likely to reach a predetermined temperature.

  Since the copper strip 12 passes through the non-oxidizing atmosphere, its surface is difficult to oxidize. The bright silver plating layer 14 can be annealed without oxidizing the copper strip 12.

  (7) Cool the copper strip 12 having the bright silver plating layer 14 annealed. The outlet 58 of the annealing furnace 52 is in the cooling liquid 66, and the copper strip 12 can be put directly into the cooling liquid 66 from a non-oxidizing atmosphere. The copper strip 12 does not touch normal air and is difficult to oxidize. The copper-based strip 12 travels through the coolant 66 and is cooled. As the cooling liquid 66, water (including pure water) or a fluorine-based inert liquid may be used. If it is a fluorine-type inert liquid, it will be hard to corrode the copper-type strip 12.

  (8) The silver-plated copper base material 10 is completed by cooling, and is made into a winding roll shape on the winding side roll 68. Before winding, it is preferable to wash and dry the silver-plated copper-based substrate 10. As a cleaning method, there is a method of immersing the silver-plated copper base material 10 in sodium triphosphate.

  The steps (1) to (8) have been described on the assumption that they are continuously performed in-line, but any steps may be performed separately. For example, after at least one of the above steps (2), (3), (4), and (5), the product manufactured so far is wound on a roll and used in the next step.

  The completed silver-plated copper base material 10 is cut into a predetermined shape and used for various switch terminals and lead frames. The silver-plated copper-based substrate 10 cut into a predetermined shape may be press-drawn to form a convex portion at a portion where the bright silver plating layer 16 is present. The shape of the convex portion is not limited, and may be a hemisphere, a cone, a truncated cone, or the like.

  As described above, the Vickers hardness of the bright silver plating layer 16 is lowered by annealing. When the silver-plated copper-based substrate 10 is press-drawn to form convex portions, the bright silver-plated layer 16 is unlikely to crack. The glossy silver plating layer 16 has a thickness of about 6 to 8 μm, and even if the convex portions are formed, the glossy silver plating layer 16 does not become too thin.

  In addition, since the glossy copper plating layer 14 and the glossy silver plating layer 16 are stacked, the glossy silver plating layer 16 is not black and has a good gloss. When the copper-based strip material 12 is matte, the matte copper-based strip material 12 is disposed so as to sandwich the glossy silver-plated layer 16 when the silver-plated copper-based substrate 10 is viewed from above, that is, the medium is not glossy. The glossy silver plating layer 16 is glossy, and the gloss of the glossy silver plating layer 16 stands out and looks good.

[Embodiment 2]
In the above-described embodiment, the bright copper plating layer 14 and the bright silver plating layer 16 are striped in the length direction of the copper strip 12, but the shapes thereof are not limited. For example, a square bright copper plating layer 72 and a bright silver plating layer 74 may be arranged in the length direction of the copper strip 12 as in the silver plated copper base 70 of FIG. 5B, the circular bright copper plating layer 78 and the bright silver plating layer 80 may be arranged in the length direction of the copper strip 12.

  Further, the bright copper plating layer 14 and the bright silver plating layer 16 are formed on a part of the one surface 18 or the other surface 20 of the copper strip 12, but the entire one surface 18 or the other surface 20 of the copper strip 12 is glossy. A copper plating layer 14 and a bright silver plating layer 16 may be formed.

[Embodiment 3]
Although described using the copper-based strip material 12, a copper-based substrate of another shape made of a copper-based material may be used. The copper base material is not limited to a planar one, and may be three-dimensional.

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

10, 70, 76: Silver-plated copper-based substrate 12: Copper-based strip material (copper-based substrate)
14, 72, 78: Glossy copper plating layers 16, 74, 80: Glossy silver plating layer 18: One side of the copper-based strip 20: The other side of the copper-based strip 22: Supply side roll of the copper-based strip 24: Roll 26: Masking tape 28: Masking tape supply side roll 30: Masking tape application roll 32, 40: Plating tank 34, 42: Plating solution 36, 44: Cathode 38, 46: Anode 48: Stripping of masking tape Roll 50: Masking tape winding side roll 52: Annealing furnace 54: Annealing furnace body 56: Inlet 58: Outlet 60: Burner 62: Ventilation port 64: Water tank 66: Coolant 68: Winding of silver-plated copper base material Take-up roll

Claims (6)

Preparing a copper-based substrate;
Forming a bright copper plating layer on the copper-based substrate;
Forming a bright silver plating layer on the bright copper plating layer;
Passing the non-oxidizing atmosphere through the copper base material on which the bright copper plating layer and the bright silver plating layer are formed, and annealing the bright silver plating layer;
The manufacturing method of the silver plating copper-type base material provided with. The method for producing a silver-plated copper-based substrate according to claim 1, wherein the bright silver-plated layer has a Vickers hardness of 70 to 90 in the annealing step. The method for producing a silver-plated copper-based substrate according to claim 1 or 2, wherein the annealing step is performed in a non-oxidizing atmosphere at 500 to 700 ° C. The method for producing a silver-plated copper-based substrate according to any one of claims 1 to 3, wherein the bright silver plating layer is formed by adding selenium or antimony to silver. A copper-based substrate;
A bright copper plating layer formed on the copper-based substrate;
A bright silver plating layer formed on the bright copper plating layer, having a thickness of 1 to 10 μm and a Vickers hardness of 70 to 90;
Silver-plated copper base material with The silver-plated copper-based substrate according to claim 5, wherein the bright silver plating layer is a plating layer obtained by adding selenium or antimony to silver.

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