JP5708437B2 - Connector terminal - Google Patents

Description

  The present invention relates to a connector terminal used for a connector.

  When joining a connector terminal to an electronic circuit board or the like, a solder material containing lead (Pb) has been conventionally used. In recent years, there has been a demand for lead-free soldering from the viewpoint of reducing environmental impact. For example, lead-free solder materials that do not contain lead, such as Sn, Sn-Cu, Sn-Bi, and Sn-Ag alloys, are used. The number of cases that can be increased.

  It is known that when a connector terminal is joined to an electronic circuit board or the like with a lead-free solder material, Sn solder whiskers are generated. When the solder whisker occurs, there is a possibility that a short circuit occurs between adjacent connector terminals due to the solder whisker. Therefore, as a countermeasure against solder whiskers, for example, design changes and process changes such as applying a moisture-proof coating on the electronic circuit board have been performed.

  As a countermeasure against solder whiskers, for example, in a connector including a connector terminal and a housing portion, a method has been proposed in which a recess is formed in a portion of the housing portion where the connector terminal is press-fitted. In this method, the solder whisker generated in the connector terminal portion is covered with the hollow portion formed in the housing portion, thereby preventing the user from touching the solder whisker and consequently preventing the solder whisker from being scattered ( For example, see Patent Document 1).

JP 2006-310089 A

  However, in general, the solder whisker generation mechanism and the solder whisker generation suppression measures have not been elucidated. Therefore, when solder whiskers are generated, there is no measure to suppress the solder whisker growth itself. Even in the example of Patent Document 1 described above, when solder whiskers are generated, the generated solder whiskers are merely covered with the recessed portions formed in the housing portion, and the generation of the solder whiskers themselves is not suppressed. .

  This invention is made | formed in view of said point, and makes it a subject to provide the connector terminal which can suppress generation | occurrence | production of solder whisker itself.

This connector terminal includes a connector terminal to be joined to another member by solder, the other member a part to be joined, it is constricted portion having a constricted annular form along the entire circumference inwardly from the outer peripheral surface The constricted portion has a bottom portion recessed inward from the outer peripheral surface, an upper end portion formed on an upper end side of the bottom portion, and a lower end portion formed on a lower end side of the bottom portion, and the upper end parts and the solder by the lower end to the damming requirements Rukoto from flowing to the outer circumferential surface.

  ADVANTAGE OF THE INVENTION According to this invention, the connector terminal which can suppress generation | occurrence | production of solder whisker itself can be provided.

It is sectional drawing which illustrates the connector terminal which concerns on this Embodiment. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which illustrates the connector terminal which concerns on a comparative example. It is sectional drawing to which the B section of FIG. 3 was expanded.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same component and the overlapping description may be abbreviate | omitted.

  FIG. 1 is a cross-sectional view illustrating a connector terminal according to this embodiment. 2 is a cross-sectional view taken along line AA in FIG. 1 and 2, the main surface of the electronic circuit board 50 (the surface on which a semiconductor element, a resistor, a capacitor, etc. (not shown) are mounted) is the XY plane, and the direction perpendicular to the XY plane is the Z direction (other figures are also shown). The same).

  Referring to FIGS. 1 and 2, the connector terminal 10 includes a constricted portion 20 and a rod-shaped portion 30. The connector terminal 10 is formed in an elongated shape. One end side of the connector terminal 10 is fixed to a housing part (not shown), and the other end side of the connector terminal 10 is sharpened so that it can be easily inserted into the through hole 51 of the electronic circuit board 50. Yes.

  The constricted portion 20 is provided in an annular shape at a portion where the connector terminal 10 is joined to the electronic circuit board 50, and forms a rod-shaped portion 30 that is thinner than the connector terminal 10. The rod-shaped portion 30 is formed such that the portion of the connector terminal 10 excluding the rod-shaped portion 30 coincides with the central axis (Z direction). The constricted portion 20 can be formed, for example, by performing press molding or the like on the connector terminal 10.

  The connector terminal 10 is inserted into a through hole 51 formed in the electronic circuit board 50 from, for example, the Z direction, and is electrically connected to a wiring pattern or the like (not shown) of the electronic circuit board 50 by a solder 60. That is, the connector terminal 10 is a member joined to the electronic circuit board 50 by the solder 60, and has a function of electrically connecting the electronic circuit board 50 and the outside. As a material of the connector terminal 10, for example, a conductive material having a high electrical conductivity such as a copper alloy can be used.

  In FIG. 1, only one connector terminal 10 is shown, but actually, a plurality of connector terminals 10 are arranged in parallel at a predetermined interval, for example, in a housing part (not shown). Each connector terminal 10 is inserted into a through-hole 51 arranged in parallel at an interval corresponding to the connector terminal 10 in the electronic circuit board 50, and is electrically connected to a wiring pattern or the like (not shown) of the electronic circuit board 50. Has been.

  The electronic circuit board 50 is obtained by, for example, forming a predetermined wiring pattern, a through hole, or the like on a glass epoxy board, a ceramic board, a paper phenol board, or the like, and mounting a semiconductor element, a resistor, a capacitor, or the like. The electronic circuit board 50 is a typical example of another member according to the present invention.

  The solder 60 has a function of electrically connecting the connector terminal 10 and a wiring pattern (not shown) of the electronic circuit board 50. As the solder 60, for example, a tin (Sn) -based lead-free solder material such as Sn, an alloy of Sn and Cu, an alloy of Sn and Bi, an alloy of Sn and Ag, and an alloy of Sn, Ag, and Cu is used. it can.

  Here, the constricted portion 20 and the rod-shaped portion 30 will be described in more detail. The constricted portion 20 is constricted in an annular shape from the outer peripheral surface of the connector terminal 10 to the inside at a portion where the connector terminal 10 is joined to the electronic circuit board 50. By forming the constricted portion 20 in the connector terminal 10, it is possible to prevent the solder 60 from flowing out to the outer peripheral surface of the connector terminal 10.

  More specifically, the constricted portion 20 includes a bottom portion 21 (a side surface of the rod-shaped portion 30) recessed inward from the outer peripheral surface of the connector terminal 10, an upper end portion 22 formed on the upper end side of the bottom portion 21, and a lower end of the bottom portion 21. And a lower end 23 formed on the side. The upper end 22 and the lower end 23 each have a function of blocking the solder 60 when the connector terminal 10 and the electronic circuit board 50 are joined by the solder 60 (details will be described later).

  The upper end 22 and the lower end 23 can be formed from, for example, a plane perpendicular to the longitudinal direction of the connector terminal 10. However, the upper end 22 and the lower end 23 are not necessarily connected to the connector terminal 10 as long as the effects of the present embodiment (the effect of blocking the solder 60 by the upper end 22 and the lower end 23 of the constricted portion 20) are not substantially impaired. It does not have to be formed from a plane perpendicular to the longitudinal direction.

  For example, the upper end 22 and the lower end 23 may be formed from a plane inclined at a predetermined angle with respect to the longitudinal direction of the connector terminal 10. Moreover, the upper end part 22 and the lower end part 23 may be formed from a curved surface, or may be formed from a combination of a curved surface and a flat surface.

  The rod-shaped portion 30 and the portion excluding the rod-shaped portion 30 of the connector terminal 10 only have to have the same center axis (Z direction), and the effects of the present embodiment (the upper end portion 22 of the constricted portion 20 and If the lower end 23 does not substantially impair the effect of blocking the solder 60, the central axis (Z direction) may be shifted.

  In addition, although the cross-sectional shape of the connector terminal 10 and the rod-shaped part 30 is circular here, it is not limited to this. For example, the cross-sectional shapes of the connector terminal 10 and the rod-shaped portion 30 may be a polygonal shape including a rectangular shape, an elliptical shape, or the like.

  Here, the specific effect which the connector terminal 10 which concerns on this Embodiment has is demonstrated, showing a comparative example.

  FIG. 3 is a cross-sectional view illustrating a connector terminal according to a comparative example. FIG. 4 is an enlarged cross-sectional view of a portion B in FIG. 3 and 4, the connector terminal 100 according to the comparative example is different from the connector terminal 10 according to the present embodiment (see FIGS. 1 and 2) in that the constricted portion 20 is not formed. . In addition, since the constricted part 20 is not formed in the connector terminal 100, the rod-shaped part 30 is not necessarily formed.

  The connector terminal 100 is inserted into a through hole 51 formed in the electronic circuit board 50 and is electrically connected to a wiring pattern or the like (not shown) of the electronic circuit board 50 by a solder 60. Since the constricted portion 20 is not formed in the connector terminal 100, the solder 60 wets the outer peripheral surface of the connector terminal 100, and the solder at the tip of the wetted portion becomes extremely thin (B portion in FIG. 3).

  The inventors have found that solder whiskers are likely to occur in the portion where the solder is extremely thin as shown in FIG. 4 (B portion in FIG. 3). The estimation mechanism of solder whisker generation investigated by the inventors is as follows. FIG. 4 shows a state where the solder whisker 69 is generated. In FIG. 4, 65 indicates tin oxide, C and D indicate regions, and F indicates compressive stress.

  The solder whisker 69 grows when the tin (Sn) in the solder 60 is pushed out by the compressive stress F generated inside. The surface of the solder 60 is oxidatively corroded, and tin oxide 65 is formed in the solder 60. At this time, oxygen in the air is taken in, and this causes volume expansion. Therefore, compressive stress F is more likely to occur in the solder 60 as the oxidation corrosion progresses and the tin oxide 65 is formed in the solder 60.

  A solder whisker 69 is generated in the portion where the solder 60 is extremely thin like the region C because there is no escape place for the compressive stress F. On the other hand, in a portion where the solder 60 is relatively thick as in the region D, the stress can be dispersed in the solder 60, so that there is little possibility that the solder whisker 69 grows due to being pushed out by the compressive stress F. Thus, the solder whisker 69 is likely to be generated in a portion where the solder 60 is extremely thin like the region C, and is less likely to be generated in a portion where the solder 60 is relatively thick like the region D.

  Here, referring to FIGS. 1 and 2 again, in the connector terminal 10 according to the present embodiment, an annular constricted portion 20 is provided at a portion where the connector terminal 10 is joined to the electronic circuit board 50. Therefore, when the connector terminal 10 and the electronic circuit board 50 are joined by the solder 60, the molten solder 60 is dammed by the upper end portion 22 and the lower end portion 23 of the constricted portion 20, and does not get wet any further. That is, the solder 60 is accommodated in the constricted portion 20 and does not flow out to the outer peripheral surface of the connector terminal 10.

  Thereby, in the connector terminal 10, the solder 60 does not have a portion where the solder 60 becomes extremely thin like the region C of the connector terminal 100. As a result, even if the tin oxide 65 is formed in the solder 60, it is possible to disperse the stress in the solder 60, so that the generation of the solder whisker 69 can be suppressed. Further, by suppressing the generation of the solder whisker 69, it is not necessary to change the design or process such as applying a moisture-proof coating on the electronic circuit board 50, so that an increase in cost can be suppressed.

The width W ₁ (the depth from the outer peripheral surface of the connector terminal 10) of the upper end portion 22 and the lower end portion 23 of the constricted portion 20 and the length L ₁ of the rod-shaped portion 30 of the constricted portion 20 are the same as those of the connector terminal 10 and the electronic device. When the circuit board 50 is joined with the solder 60, it can be determined so that the solder 60 is reliably dammed at the upper end portion 22 and the lower end portion 23. However, since suitable numerical values of the width W _{1 of} the upper end portion 22 and the lower end portion 23 and the length L ₁ of the rod-like portion 30 depend on the size of the through hole 51 of the electronic circuit board 50 and the amount of the solder 60, A suitable numerical value cannot be shown.

  The preferred embodiment of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described embodiment without departing from the scope of the present invention. And substitutions can be added.

DESCRIPTION OF SYMBOLS 10, 100 Connector terminal 10 Terminal main body 20 Constriction part 21 Bottom part 22 Upper end part 23 Lower end part 30 Bar-shaped part 50 Electronic circuit board 51 Through-hole 60 Solder 65 Tin oxide 69 Solder whisker C, D area F Compressive stress L ₁ Length W ₁ width

Claims (1)

A connector terminal joined to another member by solder,
A constricted portion that is constricted in an annular shape over the entire circumference from the outer peripheral surface to the inside is formed in the portion to be joined to the other member ,
The constricted portion has a bottom portion recessed inward from the outer peripheral surface, an upper end portion formed on an upper end side of the bottom portion, and a lower end portion formed on a lower end side of the bottom portion, and the upper end portion and the connector terminal to which the solder by the lower end and wherein the dam Rukoto from flowing to the outer circumferential surface.

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