JP5925422B2 - Joint terminal and manufacturing method thereof - Google Patents

Description

  The present invention relates to a joint terminal and a manufacturing method thereof, and more particularly to a joint terminal used when an electronic component is attached to a surface of a substrate by a surface mounting technique and a manufacturing method thereof.

  Conventionally, in order to attach an electronic component to a substrate, a surface mounting technique for directly soldering the electronic component to the surface of the substrate is known. In order to attach electronic components to the printed circuit board by this surface mounting technology, the board connection parts (fixed parts) of a pair of joint terminals are soldered and fixed to the surface of the printed circuit board, and then the electronic part holding parts of these joint terminals A method is known in which an electronic component is sandwiched and fixed by a (pressure contact portion).

  As such joint terminal materials, inexpensive Sn plating materials in which Sn plating is applied to the outermost layer of materials such as copper and copper alloys are widely used from the viewpoints of corrosion resistance, contact reliability, solderability and economy. Has been.

  This Sn plating is generally performed by electroplating. In order to remove internal stress of the Sn plating material and suppress the generation of whiskers, after Sn plating (the surface of the Sn plating material is heated to melt Sn). Reflow processing is performed (see, for example, Patent Document 1).

  When reflow treatment is performed after Sn plating in this way, a part of Sn diffuses into the material and the base component to form a compound layer (for example, a Cu-Sn compound layer in the case of a material made of copper or a copper alloy). An Sn layer having a soft melt-solidified structure is formed on this compound layer. The Sn layer that has become a soft melt-solidified structure plays an extremely important role in order to obtain excellent contact reliability, corrosion resistance, and solder wettability.

JP 2003-293187 A (paragraph number 0010)

  However, when the reflow process is performed after Sn plating, there is a problem that molten Sn gathers at the center of the material due to surface tension, the Sn plating film becomes thin at the edge portion of the material, and solder wettability decreases. In particular, when using a Sn-plated material subjected to reflow treatment as a material for a joint terminal, it is necessary to suppress a decrease in solder wettability at the edge portion of the board connecting portion, which is a soldered portion of the joint terminal. .

  Therefore, in view of such a conventional problem, an object of the present invention is to provide a joint terminal and a method for manufacturing the joint terminal, which can suppress a decrease in solder wettability of the edge portion of the board connecting portion.

  As a result of diligent research to solve the above problems, the present inventors have found that a flat plate-like electronic component holding portion and a flat plate-like shape extending from one end of the electronic component holding portion in a substantially vertical direction to the electronic component holding portion. After forming the shape of the joint terminal composed of the substrate connection portion, a plurality of fine grooves are formed in the substrate connection surface on the opposite side of the electronic component holding portion of the substrate connection portion, and then reflow after Sn plating is performed. By performing the treatment, it was found that the decrease in solder wettability of the edge portion of the board connecting portion can be suppressed, and the present invention has been completed.

  In other words, the joint terminal manufacturing method according to the present invention includes a flat plate-like electronic component holding portion and a flat plate-like substrate connecting portion extending from one end of the electronic component holding portion in a direction substantially perpendicular to the electronic component holding portion. After forming the shape of the joint terminal, a plurality of fine grooves are formed on the substrate connection surface, which is the surface opposite to the electronic component holding portion of the substrate connection portion, and then reflow processing is performed after Sn plating is performed. And

  In this joint terminal manufacturing method, the shape of the joint terminal is preferably a shape formed by pressing and bending a plate material as a material. The plurality of fine grooves are preferably formed at the edge portions on both sides in the width direction of the substrate connection surface, and preferably extend in the longitudinal direction over the entire length from one end portion to the other end portion in the longitudinal direction of the substrate connection surface. Moreover, it is preferable that the plurality of fine grooves are fine grooves each having a width of 20 to 100 μm and a depth of 0.1 to 10 μm, and spaced apart with a pitch of 20 to 150 μm. Furthermore, it is preferable to form a Sn plating film having a thickness of 2 to 8 μm by performing Sn plating.

  Further, the joint terminal according to the present invention is a joint end composed of a flat plate-like electronic component holding portion and a flat plate-like board connecting portion extending from one end portion of the electronic component holding portion in a direction substantially perpendicular to the electronic component holding portion. A plurality of fine grooves are formed on the substrate connection surface, which is the surface opposite to the electronic component holding portion of the substrate connection portion, and a reflow process is performed after the Sn plating film is formed on the surface. .

  In this joint terminal, it is preferable that a plurality of fine grooves are formed at the edge portions on both sides in the width direction of the substrate connection surface, and extend in the longitudinal direction over the entire length from one end to the other end in the longitudinal direction of the substrate connection surface. It is preferable. Moreover, it is preferable that the plurality of fine grooves are fine grooves each having a width of 20 to 100 μm and a depth of 0.1 to 10 μm, and spaced apart with a pitch of 20 to 150 μm. Moreover, it is preferable that the thickness of Sn plating film is 2-8 micrometers.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the solder wettability of the edge part of the board | substrate connection part of a joint terminal can be suppressed.

It is a figure which shows the joint terminal by this invention, (a) is the front view seen from the electronic component holding surface of the electronic component holding part of a joint terminal, (b) is a side view of a joint terminal, (c) is a joint. It is a bottom view of the board | substrate connection part of a terminal. It is an enlarged view which shows the board | substrate connection surface which is a bottom face of the board | substrate connection part of the joint terminal of FIG. It is a perspective view which shows the use condition of the joint terminal of FIG.

  Embodiments of a joint terminal and a method for manufacturing the joint terminal according to the present invention will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, an embodiment of a joint terminal 10 according to the present invention includes a substantially rectangular flat plate-shaped electronic component holding portion (pressure contact portion) 12 and one end of the electronic component holding portion 12 bent substantially vertically. It consists of a substantially rectangular flat plate-like substrate connecting portion (fixed portion) 14 formed so as to be processed into a substantially L-shape. The surface of the electronic component holding portion 12 opposite to the board connecting portion 14 is an electronic component holding surface (pressure contact surface) 12a, and the surface of the board connecting portion 14 opposite to the electronic component holding portion 12 is a board connecting surface ( Fixed surface) 14a.

  As shown in FIG. 2, the board connection is made at the edge portions (regions having a predetermined width from the edge) on both sides in the width direction (perpendicular to the longitudinal direction and the thickness direction) of the board connection surface 14a of the board connection portion 14. A plurality of fine grooves 14b extending in the longitudinal direction over the entire length from one end to the other end in the longitudinal direction of the surface 14a (with a width of 20 to 100 μm, a depth of 0.1 to 10 μm, and a pitch of 20 to 150 μm) are formed. These fine grooves 14b may be formed not only on the edge portion of the substrate connection surface 14a but also on the entire surface of the substrate connection surface 14a.

  In this way, the joint terminal 10 in which the fine groove 14b is formed on the substrate connection surface 14a has a Ni plating film having a thickness of 0.5 to 2.0 μm formed on the material made of copper or copper alloy by Ni plating. Then, after a Sn plating film having a thickness of 2 to 8 μm is formed thereon by Sn plating, a reflow treatment is performed.

  As shown in FIG. 3, when the electronic component 20 is attached to the substrate 30 by surface mounting technology, the joint terminals 10 are connected to the surface of the substrate 30 by soldering the pair of joint terminals 10, and then the joint terminals are connected. The electronic component 20 is sandwiched and fixed by the ten electronic component holders 12.

  In the embodiment of the method for manufacturing the joint terminal 10 according to the present invention, first, a plate material made of copper, a copper alloy, or the like is prepared as a material, and the plate material is pressed and bent to connect a substantially rectangular flat plate-like substrate. The portion 14 is formed into a shape of a substantially L-shaped joint terminal 10 that rises substantially vertically from one end of the substantially rectangular flat plate-shaped electronic component holding portion 12.

  Next, the joint terminal 10 is fixed, and the edge portion (region from the edge to 0.2 mm in the width direction) on both sides in the width direction of the board connection surface 14a which is the bottom surface of the board connection portion 14 of the joint terminal 10 is set to 1 While applying a load of ˜10 N, the metal file is rubbed once or a plurality of times (5 times or less in the present embodiment) in the longitudinal direction of the substrate connection surface 14a, so that one end to the other end in the longitudinal direction of the substrate connection surface 14a A plurality of fine grooves 14b (width 20-100 μm, depth 0.1-10 μm, pitch 20-150 μm) extending in the longitudinal direction over the entire length are formed. These fine grooves 14b may be formed not only on the edge portion of the substrate connection surface 14a but also on the entire surface of the substrate connection surface 14a.

  Next, after performing degreasing and pickling as pretreatment of plating of the joint terminal 10 in which the fine groove 14b is formed, Ni plating is performed to form a Ni plating film having a thickness of 0.5 to 2.0 μm, and then , Sn plating is performed to form a 2 to 8 μm thick Sn plating film.

  Next, after performing the oxidation prevention treatment and hot water washing of the joint terminal 10 subjected to these plating, it is dried by air blow or the like, and then placed in a furnace at a temperature of 500 to 650 ° C. in the atmosphere for 0.5 to 2 seconds. Reflow processing is performed by holding.

  In addition, it is preferable to wash with water between each process of pre-processing, plating, and an intermediate process.

  Hereinafter, embodiments of the joint terminal and the manufacturing method thereof according to the present invention will be described in detail.

[Example]
First, a brass plate material having a thickness of 0.5 mm is prepared as a raw material, and this brass plate material is pressed and bent so that the size of the electronic component holding portion (pressure contact portion) is 5 mm wide × 6 mm high, and is connected to the board. The substrate connection surface (fixed surface), which is the bottom surface of the portion (fixed portion), was formed into a joint terminal shape (shape shown in FIG. 1) having a size of 1 mm × 5 mm. In addition, the chamfering process of the edge part of the board | substrate connection surface which is a bottom face of the board | substrate connection part of a joint terminal was not performed.

  Next, the joint terminal is fixed, and as shown in FIG. 2, edge portions on both sides in the width direction of the board connection surface, which is the bottom surface of the board connection portion of the joint terminal (region from the edge to 0.2 mm in the width direction). In addition, the metal file is rubbed once in the longitudinal direction of the substrate connection surface while applying a load of 1 to 10 N, and the fineness extending in the longitudinal direction of the substrate connection surface over the entire length from one end to the other end in the longitudinal direction of the substrate connection surface About 10 grooves each were formed. When the width, depth and pitch of these fine grooves were measured with a laser microscope at a magnification of 200 times, the width of the fine grooves was 20 to 100 μm, the depth was 0.1 to 10 μm, and the pitch was 20 to 150 μm. there were.

Next, degreasing and pickling are performed as pretreatment for plating the joint terminals in which fine grooves are formed, and then Ni plating is performed with a sulfamic acid bath at a current density of 5 A / dm ² so that the thickness becomes 1 μm. A plating film was formed, and then Sn plating was performed with an organic acid plating bath at a current density of 5 A / dm ² to form a Sn plating film having a thickness of 3.5 μm. In addition, these plating was performed by the hoop plating in the state which connected the some joint terminal with the carrier.

  Thus, about the joint terminal which gave Ni plating and Sn plating, the thickness of the Ni plating film and Sn plating film of the board | substrate connection surface which is a bottom face of a board | substrate connection part was measured. The thickness of the Ni plating film is measured using a fluorescent X-ray film thickness meter, and the thickness of the Sn plating film is one end in the longitudinal direction (of the board connection surface) with the joint terminal embedded in the resin and the joint terminal together with the resin. And cut perpendicularly to the longitudinal direction at a position of 1 mm from the surface, and wet-polishing (polishing using numbers # 80, # 400, # 1000 and # 2000 in this order) and buffing (alumina abrasive) And mirror-finished) and observed with a scanning electron microscope (SEM) at a magnification of 3000, and the thickness was directly measured from the SEM image. As a result, the thickness of the underlying Ni plating film is 1 μm, and the thickness of the Sn plating film is 3.5 μm at the portion (edge portion) of 0.01 mm in the width direction from the edge, and is 0.00 μm in the width direction from the edge. It was 3.5 μm at the 5 mm portion (central portion).

  Next, after oxidation treatment and hot water washing of these plated joint terminals, they were dried by air blow, and then reflow treatment was performed by holding them in a furnace at a temperature of 550 ° C. for 1 second in the atmosphere. It was.

  In addition, it washed with water between each process of pre-processing, plating, and an intermediate process.

  Thus, about the joint terminal which performed the reflow process, the thickness of the Sn plating film of the board | substrate connection surface which is a bottom face of a board | substrate connection part was measured by the method similar to the above. As a result, the thickness of the Sn plating film was 2.7 μm at the 0.01 mm portion (edge portion) in the width direction from the edge, and 3.7 μm at the 0.5 mm portion (center portion) from the edge in the width direction. The ratio of (thickness of the edge portion) / (thickness of the central portion) as an index of the uniformity of the film thickness distribution was 0.73. The soldering strength was very good.

[Comparative Example 1]
A joint terminal was prepared by the same method as in the example except that the fine groove was not formed, and the thickness of the Sn plating film on the substrate connection surface, which is the bottom surface of the substrate connection portion before and after the reflow treatment, was measured. As a result, the thickness of the Sn plating film before the reflow treatment was 3.5 μm at the 0.01 mm portion (edge portion) in the width direction from the edge, and 3 at the 0.5 mm portion (center portion) from the edge in the width direction. The thickness of the Sn plating film after the reflow treatment is 0.4 μm at the portion (edge portion) of 0.01 mm in the width direction from the edge, and the portion (center portion) of 0.5 mm in the width direction from the edge. Then, the ratio of (thickness of the edge portion) / (thickness of the central portion) as an index of the uniformity of the film thickness distribution was 0.08. The soldering strength was normal strength.

[Comparative Example 2]
A joint terminal is prepared by the same method as in the example except that the Sn plating film is formed so as to have a thickness of 7.0 μm without forming a fine groove, and is a bottom surface of the substrate connection part before and after the reflow process. The thickness of the Sn plating film on the substrate connection surface was measured. As a result, the thickness of the Sn plating film before the reflow treatment is 7.0 μm at the portion (edge portion) of 0.01 mm in the width direction from the edge, and is 7 at the portion (center portion) of 0.5 mm in the width direction from the edge. The thickness of the Sn plating film after the reflow treatment is 0.4 μm at the portion (edge portion) of 0.01 mm in the width direction from the edge, and the portion (center portion) of 0.5 mm in the width direction from the edge. Then, the ratio of (thickness of edge portion) / (thickness of center portion) as an index of uniformity of film thickness distribution was 0.04. The soldering strength was normal strength.

[Comparative Example 3]
A joint terminal was prepared by the same method as in the example except that the fine groove was not formed and the reflow treatment was not performed, and the thickness of the Sn plating film on the substrate connection surface, which is the bottom surface of the substrate connection portion, was measured. . As a result, the thickness of the Sn plating film was 3.5 μm at the 0.01 mm portion in the width direction (edge portion) from the edge, and 3.5 μm at the 0.5 mm portion (center portion) in the width direction from the edge. It was. The soldering strength was very good.

[Comparative Example 4]
A joint terminal is formed in the same manner as in the embodiment except that one fine groove having a width of about 50 μm and a depth of about 30 μm is formed in the 0.02 mm width portion from both edges in the width direction of the board connection surface. The thickness of the Sn plating film on the substrate connection surface, which is the bottom surface of the substrate connection portion before and after the reflow treatment, was measured. As a result, the thickness of the Sn plating film before the reflow treatment was 3.5 μm at the 0.01 mm portion (edge portion) in the width direction from the edge, and 3 at the 0.5 mm portion (center portion) from the edge in the width direction. The thickness of the Sn plating film after the reflow treatment is 0.4 μm at the portion (edge portion) of 0.01 mm in the width direction from the edge, and the portion (center portion) of 0.5 mm in the width direction from the edge. Was 4.6 μm, and the ratio of (thickness of edge portion) / (thickness of central portion) as an index of uniformity of film thickness distribution was 0.09. The soldering strength was normal strength.

10 Joint terminal 12 Electronic component holding part (pressure contact part)
12a Electronic component holding surface (pressure contact surface)
14 Board connection part (fixed part)
14a Board connection surface (fixed surface)
14b Fine groove 20 Electronic component 30 Substrate

Claims (9)

After forming the shape of a joint terminal composed of a flat plate-like electronic component holding portion and a flat plate-like substrate connecting portion extending in a substantially vertical direction from one end of the electronic component holding portion to the electronic component holding portion, A feature is that a plurality of fine grooves extending in the longitudinal direction are formed in edge portions on both sides in the width direction of the substrate connection surface , which is the surface opposite to the electronic component holding portion, and then reflow processing is performed after Sn plating is performed. The manufacturing method of the joint terminal. The method of manufacturing a joint terminal according to claim 1, wherein the shape of the joint terminal is a shape formed by pressing and bending a plate material as a material. Wherein the plurality of fine grooves, and wherein the extension building over the entire length from one longitudinal end portion of the substrate connecting surface to the other end, the production method of the joint terminal according to claim 1 or 2. Wherein the plurality of fine grooves, respectively width 20 to 100 [mu] m, a fine groove depth 0.1 to 10 [mu] m, and wherein the spaced apart at a pitch 20 to 150 [mu] m, more of claims 1 to 3 The manufacturing method of the joint terminal of crab. Wherein by performing Sn plating, and forming a Sn plating film thickness 2 to 8 m, the production method of the joint terminal according to any one of claims 1 to 4. An electronic component holding portion of the board connecting portion at a joint end composed of a flat plate-like electronic component holding portion and a flat plate-like substrate connecting portion extending from one end portion of the electronic component holding portion in a direction substantially perpendicular to the electronic component holding portion. A plurality of fine grooves extending in the longitudinal direction are formed at the edge portions on both sides in the width direction of the substrate connection surface , which is the surface opposite to the surface, and an Sn plating film is formed on the surface. of Sn Sodea Rukoto characterized, joint terminal. Wherein the plurality of fine grooves, and wherein the extension Biteiru over the entire length from one longitudinal end portion of the substrate connecting surface to the other end, the joint terminal according to claim 6. Wherein the plurality of fine grooves, respectively width 20 to 100 [mu] m, a fine groove depth 0.1 to 10 [mu] m, characterized in that it is spaced at a pitch 20 to 150 [mu] m, in claim 6 or 7 Listed joint terminal. The joint terminal according to any one of claims 6 to 8 , wherein the Sn plating film has a thickness of 2 to 8 µm.

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