JP5299295B2 - Terminal bracket and connection structure of terminal bracket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent faulty solder. <P>SOLUTION: The terminal metal fitting 10 is provided with a terminal body 11 inserted into a through hole 61 and passing through solder 40 in a circuit board 60 on which the solder 40 containing tin as a major ingredient is so printed as to cover the opening of the through hole 61. A first plating layer 31 formed by plating from a metal exhibiting a lower wettability than tin (Sn), nickel (Ni), for example, is formed on the end of the terminal body 11 in the direction of its insertion. A second plating layer 32 formed of tin (Sn) plating is formed in the part of the surface of the terminal body 11 except the end in the direction of its insertion. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a terminal fitting and a connection structure between the terminal fitting and a circuit board.

  As a terminal fitting to be solder-connected to a printed circuit board (hereinafter referred to as a circuit board), the one described in Patent Document 1 is known. The terminal fitting includes a terminal body that is inserted into a through hole formed in a circuit board. On the surface of the circuit board, solder mainly composed of tin is printed so as to cover the opening of the through hole, and the terminal body is inserted into the through hole while penetrating the solder. Thereafter, the circuit board is passed through a reflow furnace, and the solder is melted and solidified to form a solder fillet between the terminal body and the circuit board. The fillet portion preferably has a shape with a gentle skirt between the opening edge portion of the through hole on both the front and back surfaces of the circuit board and the surface of the terminal body. The solder is mainly composed of tin, and the entire surface of the terminal fitting is tin-plated.

JP 2003-51349 A

  By the way, in the case of the conventional terminal fitting, the solder may be dragged to the front end portion (insertion direction front end portion) of the terminal main body that passes through the through hole, and the solder may adhere to the surface of the front end portion of the terminal main body. As a result, the solder melted in the subsequent reflow process remains at the tip of the terminal body, and the solder 80 hangs down at the tip 91 of the terminal body 90 that has passed through the through hole 71 of the circuit board 70 as shown in FIG. There was a state. As a result, the fillet shape as described above was not formed, and there was a situation that it had to be treated as a defective product.

  The present invention has been completed based on the above circumstances, and an object thereof is to prevent solder defects.

  As a means for achieving the above object, the invention of claim 1 is characterized in that a solder mainly composed of tin is inserted into the through hole with respect to a circuit board printed so as to cover the opening of the through hole. A terminal body that penetrates the solder is provided, and a first plating layer made of plating with a metal having lower wettability than tin is formed on the surface of the distal end portion in the insertion direction of the terminal body. It is characterized in that a second plating layer made of tin plating is formed on the portion excluding the tip in the insertion direction.

  According to a second aspect of the present invention, in the first aspect of the present invention, a suction groove capable of sucking up the solder in a molten state is formed on the surface of the terminal main body in the length direction from the distal end side in the insertion direction of the terminal main body. It is characterized by being formed along.

  Invention of Claim 3 is a connection structure which connects the terminal metal fitting of Claim 1 or 2 to the said circuit board, Comprising: Between the surface of the said terminal main body, and the internal peripheral surface of the said through hole, the said solder | pewter A fillet portion is formed after melting and solidifying, and the end portion of the first plating layer is positioned at the same height as the raised end portion of the fillet portion or at the distal end side in the insertion direction with respect to the raised end portion of the fillet portion. It is characterized by

<Invention of Claim 1>
When the terminal body is inserted into the through hole, solder may adhere to the distal end side in the insertion direction of the terminal body. However, according to the present invention, the first plating layer made of a metal having lower wettability than tin, which is the main component of the solder, is formed on the surface of the distal end portion in the insertion direction of the terminal main body. Solder is sucked up from the front end side of the terminal body in the insertion direction to the second plating layer side of the tin plating. As a result, a good fillet shape is realized and solder failure is prevented.

<Invention of Claim 2>
Since a suction groove capable of sucking up molten solder on the surface of the terminal body is formed along the length direction from the distal end side in the insertion direction of the terminal body, the solder is preferably sucked up toward the second plating layer. It is done. As a result, a better fillet shape is realized.

<Invention of Claim 3>
Since the end portion of the first plating layer is located at the same position as the raised end portion of the fillet portion or at the distal end side in the insertion direction relative to the raised end portion of the fillet portion, the solder remains on the distal end side in the insertion direction of the terminal body. Is avoided and solder failure is reliably prevented.

In the terminal metal fitting which concerns on Embodiment 1 of this invention, it is a perspective view of a terminal main body. It is a bottom view of a terminal body. It is sectional drawing which shows the state before inserting a terminal main body into the through hole of a circuit board. It is sectional drawing which shows the state which inserted the terminal main body into the through hole of the circuit board, and formed the fillet part. In background art, it is sectional drawing which shows the state which solder dripped at the front-end | tip part of the terminal main body, and caused the solder defect.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. The terminal fitting 10 according to the first embodiment is attached to a board connector (not shown) and attached to a printed circuit board (hereinafter, circuit board 60) together with the board connector.

  The terminal fitting 10 includes a terminal main body 11 whose base material portion is made of a conductive metal made of copper or a copper alloy, is L-shaped or linear as a whole, and is led out from the end face of the board connector. The terminal body 11 has a rod shape with a substantially square section with rounded corners, and is inserted into a through hole 61 formed in the circuit board 60 from above and fixedly connected. As shown in FIGS. 1 and 2, the leading end portion of the terminal main body 11 (the leading end portion in the direction of insertion into the circuit board 60) is formed with a lead-in portion 12 that is tapered by cutting out four surfaces in a tapered shape. Has been. The front end surface of the terminal body 11 is substantially square.

  In addition, a pair of left and right recesses 13 are formed in the leading end portion of the terminal body 11 by notching the two opposing surfaces of the guiding portion 12. The recess 13 is formed to extend in the length direction from the tip of the terminal body 11 to a range slightly above the guide portion 12. And the recessed part 13 is made into the form which increases a width dimension gradually toward an upper end. Specifically, the bottom surface of the recess 13 is configured by a first slope 14 that gradually expands outward as it goes to the upper end, and the inner surfaces on both sides of the recess 13 expand outward from both side edges of the first slope 14. The upper end surface of the recess 13 is formed by a third inclined surface 16 that expands outward from the upper edge of the first inclined surface 14. The tip of the recess 13 is open to the tip surface of the terminal body 11, and the lower ends of the first slope 14 and the second slope 15 face the lower end of the terminal body 11.

  Further, the terminal body 11 is formed with a cut-out groove 17 that is elongated from the distal end portion thereof along the length direction. The lower end of the suction groove 17 opens to the upper end surface (third inclined surface 16) of the recess 13, and the upper end of the suction groove 17 is a height that enters the through hole 61 in a state where the terminal body 11 is inserted into the through hole 61. The position has been reached. The siphoning groove 17 has a pair of left and right introduction portions 18 having a substantially constant depth over the entire length and expanding toward the upper end surface of the recess 13.

  The bottom surface of the suction groove 17 is constituted by a flat surface 19 that stands substantially vertically (see FIG. 3), and the inner surfaces of both sides of the suction groove 17 rise from the both side edges of the flat surface 19 at a substantially right angle to the flat surface 19. The first straight surface 21 and the fourth inclined surface 22 expanding outward from the outer edge of the first straight surface 21, and the upper end surface of the suction groove 17 is substantially perpendicular to the flat surface 19 from the upper edge of the flat surface 19. The second straight surface 23 rises to the second straight surface 23 and the fifth inclined surface 24 that spreads outward from the outer edge of the second straight surface 23.

  A first plated layer 31 plated with nickel (Ni) is formed on the surface of the tip of the terminal body 11. The first plating layer 31 is formed over the entire guiding portion 12. A second plating layer 32 plated with tin (Sn) is formed on the surface of the terminal body 11 except for the tip (first plating layer 31). In this case, the second plating layer 32 is formed over the entire terminal fitting 10 except for the tip of the terminal body 11.

  The structure of the terminal fitting 10 according to the first embodiment is as described above. Next, a method for connecting the terminal fitting 10 to the circuit board 60 will be described.

  First, a solder paste is printed on the surface of the circuit board 60. At this time, the solder paste enters the through hole 61 and the opening of the through hole 61 is covered with the solder 40 as shown in FIG.

  In this state, the board connector is disposed on the surface of the circuit board 60. In the process of pulling down the board connector onto the circuit board 60, the terminal body 11 is inserted into the through hole 61 from the tip. In the insertion process, the leading portion 12 (including the leading portion 12) passes through the solder 40 while being guided to insert the terminal main body 11 by the leading portion 12, and comes out to the back side of the circuit board 60. . As a result, the tip of the terminal body 11 is disposed at a position protruding downward from the back surface of the circuit board 60, and the cream-like solder 40 adheres to the surface of the terminal body 11. At this time, the solder 40 is satisfactorily captured in the recess 13.

  Next, the circuit board 60 is heated in a reflow furnace (not shown). Then, the solder 40 is melted, and the melted solder 40 flows between the surface of the terminal body 11 and the inner peripheral surface of the through hole 61. At this time, even if the solder 40 is attached to the tip of the terminal body 11, nickel (Ni) having lower wettability than tin (Sn), which is the main component of the solder 40, is attached to the tip of the terminal body 11. ) Is formed, the solder 40 hardly stays at the tip of the terminal body 11, while the solder is disposed on the second plating layer 32 side made of tin (Sn) plating located above the terminal 40. 40 becomes easy to shift. Further, the solder 40 that has entered the recess 13 is sucked into the suction groove 17 from the introduction portion 18 by capillary action, so that the solder 40 is prevented from staying at the tip of the terminal body 11.

  Thereafter, when the solder 40 is cooled and solidified, the terminal fitting 10 is connected to the conductive portion 50 formed on the inner peripheral surface of the through hole 61 and the opening edge portions of the front and back surfaces of the through hole 61 through the solder 40. Is done. When the terminal fitting 10 is thus connected to the circuit board 60, as shown in FIG. 4, a fillet having a gentle skirt between the opening edge portions of the front and back surfaces of the through hole 61 and the surface of the terminal body 11. Part 55 is formed. The fillet portion 55 is located above the guiding portion 12, in other words, the upper end of the first plating layer 31 is located below (the leading end side in the insertion direction) the lower end of the rise of the fillet portion 55.

  As described above, according to the first embodiment, when the terminal body 11 is inserted into the through hole 61, even if the solder 40 adheres to the distal end side of the terminal body 11, it is then melted in the reflow furnace. Since the solder 40 is sucked up from the front end side of the terminal body 11 on the first plating layer 31 side to the second plating layer 32 side, the solder 40 is prevented from staying on the front end side of the terminal body 11. As a result, a fillet portion 55 having a good shape is formed between the circuit board 60 and the terminal body 11, and solder defects are prevented. In this case, since the upper end of the first plating layer 31 is positioned below the rising lower end of the fillet portion 55, solder failure is reliably prevented.

  Further, since the sucking groove 17 capable of sucking up the molten solder 40 on the surface of the terminal main body 11 is formed along the length direction from the distal end side of the terminal main body 11, the solder 40 is the second plating layer 32. Is more preferably sucked up. As a result, the shape of the fillet portion 55 becomes better.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) The first plating layer is a layer made of alloy plating with copper (Cu) / tin (Sn), a layer made of alloy plating with nickel (Ni) / tin (Sn), or a layer made of plating with iron (Fe) Or a layer made of chromium (Cr) plating. Since these are also made of a metal having lower wettability than tin (Sn) like nickel (Ni), solder containing tin (Sn) as a main component is preferably sucked up to the second plating layer side.
(2) The upper end of the first plating layer may be located at the same height as the lower end of the rise of the fillet portion.
(3) The second plating layer may be laminated on the first plating layer in the portion of the surface of the terminal body excluding the tip.

DESCRIPTION OF SYMBOLS 10 ... Terminal metal fitting 11 ... Terminal main body 17 ... Suction groove 31 ... 1st plating layer 32 ... 2nd plating layer 40 ... Solder 55 ... Fillet part 60 ... Circuit board 61 ... Through hole

Claims (3)

With respect to the circuit board printed so that the solder containing tin as a main component covers the opening of the through hole, the terminal body inserted into the through hole and penetrating the solder,
A first plating layer made of plating with a metal having lower wettability than tin is formed on the surface of the terminal body in the insertion direction, and a portion of the surface of the terminal body except for the insertion direction tip is tin. A terminal fitting, wherein a second plating layer made of plating is formed.   The terminal fitting according to claim 1, wherein a suction groove capable of sucking up the solder in a molten state is formed on a surface of the terminal main body along a length direction from a distal end side in the insertion direction of the terminal main body. A connection structure for connecting the terminal fitting according to claim 1 or 2 to the circuit board,
A fillet portion is formed between the surface of the terminal body and the inner peripheral surface of the through hole after the solder is melted and solidified, and the end portion of the first plating layer is the same as the raised end portion of the fillet portion. The terminal fitting connection structure, wherein the terminal fitting connection structure is located at a height position or a front end side in the insertion direction with respect to a raised end portion of the fillet portion.

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