Press-fit terminal

Abstract

The present invention provides a press-fit terminal capable of dispersing stress generated by deformation when inserted into a through hole while suppressing interference or contact with the through hole. A press-fit terminal (1) is provided with: a tip section (10) positioned at the tip; a base section (20) positioned rearward of the tip section (10); and a pair of elastic contact pieces (30) which are disposed facing each other across an opening (40), are positioned between the tip (10) and the base (20), connect the tip (10) and the base (20), and protrude outward in the width direction, a stress dispersion section (50) being provided in a region including a boundary between the tip (10) and the elastic contact pieces (30), the stress dispersion section (50) has an outer narrow section configured such that a side edge (1a) on the outer side in the width direction enters the inner side in the width direction, the outer narrow section being located on the front side of the boundary section, and the inner narrow section being located on the rear side of the boundary section. The inner narrow portion is configured such that the peripheral edge (41) of the opening (40) protrudes outward in the width direction.

Description

Technical Field

[0001] This invention relates to press-fit terminals. Background Technology

[0002] For electronic circuits formed on a circuit board, press-fit terminals are used to establish electrical connections with external components of the circuit board. A press-fit terminal is a tab-shaped connection terminal that is inserted into a through-hole in the circuit board and has an elastic contact piece that can deform elastically. When the press-fit terminal is pressed into the through-hole, the elastic contact piece elastically contacts the inner wall of the through-hole, thus establishing a conductive connection with the through-hole.

[0003] In press-fit terminals, to ensure connection reliability against the effects of temperature or vibration, and to prevent the press-fit terminal from detaching from the circuit board due to external forces such as vibration, it is necessary to ensure a sufficiently large holding force, i.e., the force required to pull the press-fit terminal out of the through-hole. On the other hand, when pressing the press-fit terminal into the through-hole, sometimes a large load is applied to the opening edge of the through-hole from the press-fit terminal, thereby generating a load on the circuit board. In addition, due to the deformation of the elastic contact piece accompanying the insertion of the press-fit terminal into the through-hole, the strain of the press-fit terminal may increase.

[0004] In Patent Documents 1 and 2, the press-fit terminals are designed from the viewpoint of ensuring high holding force and reducing the load applied to the substrate when the press-fit terminal is pressed into the through hole. On the other hand, in Patent Document 3, the press-fit terminal inserted into the through hole is designed from the viewpoint of dispersing the stress generated by the deformation of the elastic contact piece. In Patent Document 3, as in this application… Figure 7 As shown, in the structure of the press-fit terminal 9' with an elastic contact piece 93 provided between the top portion 91 and the base portion 92, stress dispersion is achieved by providing a stress-dispersing portion 95 protruding in the same direction as the bulging direction of the elastic contact piece 93 in at least one of the regions including the boundary between the top portion 91 and the elastic contact piece 93 and the boundary between the base portion 92 and the elastic contact piece 93. As a result, the generation of large strain in the press-fit terminal can be suppressed. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-127610 Patent Document 2: International Publication No. 2008 / 038331 Patent Document 3: Japanese Patent Application Publication No. 2018-63937 Summary of the Invention The problem that the invention aims to solve

[0006] In recent years, with the miniaturization of electric or electronic equipment and the high integration of electronic circuits, the through holes formed in the circuit board have also been made smaller in diameter. On the other hand, there are limits to designing the press-fit terminal inserted into the through hole to have a narrow width in order to accommodate the small diameter of the through hole. This is because, as described above, in order to ensure the holding force of the press-fit terminal inserted into the through hole, it is necessary to apply a contact load large enough to the inner wall surface of the through hole from the press-fit terminal, but for this purpose, it is necessary to make the elastic contact piece have a certain degree of width to ensure the restoring force due to elastic deformation. In addition, it is because it is difficult to manufacture a press-fit terminal having a width that is too narrow by press working. Thus, in the case where there are limits to forming the press-fit terminal to have a narrow width, if the through hole is made smaller in diameter, the width of the press-fit terminal becomes relatively large with respect to the diameter of the through hole.

[0007] As Figure 7 described in Patent Document 3, by providing the stress dispersing portion 95 having a protruding shape in the region including the boundary portion of the elastic contact piece 93 and the tip end portion 91, it is possible to disperse the stress generated in conjunction with the deformation of the elastic contact piece 93, but by the stress dispersing portion 95 having a protruding shape, it is likely that each portion of the through hole from the opening edge portion and the stress dispersing portion 95 interfere or come into contact with each other when the press-fit terminal 9' is inserted into the through hole. In particular, as described above, in the case where the width of the press-fit terminal 9' becomes relatively large with respect to the diameter of the through hole, it is easy to cause the stress dispersing portion 95 to interfere or come into contact with the through hole. Thus, it is difficult to perform the insertion of the press-fit terminal into the through hole. In addition, the force required for the insertion of the press-fit terminal (insertion force) also becomes large. Thus, in the case where the stress dispersing portion having a protruding shape is formed in the press-fit terminal, it is difficult to reduce the width of the press-fit terminal while taking into account the stress dispersion of the stress dispersing portion and avoiding the interference or contact with the through hole.

[0008] Therefore, an object of the present application is to provide a press-fit terminal that can disperse the stress generated by the deformation at the time of insertion into a through hole while suppressing the interference or contact with the through hole. Approach for solving the problem

[0009] The press-fit terminal according to the present application is inserted into a through-hole provided in a circuit board, the direction of insertion of the press-fit terminal with respect to the through-hole is taken as the front direction, the opposite direction is taken as the rear direction, and the direction orthogonal to the direction of insertion is taken as the width direction. The press-fit terminal has a tip end portion at the front end, a base portion at the rearward of the tip end portion, and a pair of elastic contact pieces disposed opposite each other with an opening portion interposed therebetween and connected to the tip end portion and the base portion and bulging toward the outside in the width direction. A stress dispersion portion is provided in a region including a boundary portion between the tip end portion and the elastic contact pieces. The stress dispersion portion has an outside narrow portion on the frontward side of the boundary portion and an inside narrow portion on the rearward side of the boundary portion. The outside narrow portion is configured such that the side edge on the outside in the width direction of the press-fit terminal enters the inside in the width direction. The inside narrow portion is configured such that the peripheral edge of the opening portion bulges toward the outside in the width direction. Effects of the Invention

[0010] According to the press-fit terminal of the present application, stress generated by deformation when inserted into the through-hole can be dispersed while interference or contact with the through-hole is suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 FIG. 1 is a plan view showing a press-fit terminal according to an embodiment of the present application. Figure 2 FIG. 2 is an enlarged view showing a stress dispersion portion of the press-fit terminal. Figure 3 FIG. 3 is a plan cross-sectional view showing a process of inserting the press-fit terminal into a through-hole of a circuit board. Figure 4 FIG. 4 is a plan cross-sectional view showing a state in which the press-fit terminal is inserted into the through-hole of the circuit board. Figure 5 FIG. 5 is a plan view showing a press-fit terminal of a deformation mode. Figure 6 FIG. 6 is a plan view showing a conventional general press-fit terminal not having a stress dispersion portion. Figure 7 FIG. 7 is a plan view showing a press-fit terminal having a stress dispersion portion composed only of a convex portion. Figure 8 The terminal shape before insertion into the through-hole, the strain distribution in the state of insertion into the through-hole, and the magnitude of the generated strain are shown for two kinds of press-fit terminals. Terminal A is a terminal not having a stress dispersion portion, and terminal B is a terminal having a stress dispersion portion having an outside narrow portion and an inside narrow portion. With respect to the strain distribution, the main drawing shows a plan view, and the drawing in the frame shows an enlarged view of the position of the outside edge. The generated strain indicates the maximum value of the strain in the strain distribution, and the case of terminal A is taken as 100%. DETAILED DESCRIPTION

[0012] [Explanation of Embodiments of the Invention] First, an embodiment of the present invention will be explained. [1] A press-fit terminal according to the present invention is inserted into a through-hole provided in a circuit board, the insertion direction of the press-fit terminal with respect to the through-hole is taken as the front direction, the opposite direction thereof is taken as the rear direction, and the direction orthogonal to the insertion direction is taken as the width direction, the press-fit terminal has a tip end portion located at the front end, a base portion located at the rearward of the tip end portion, and a pair of elastic contact pieces disposed opposite each other across an opening portion, located between and connecting the tip end portion and the base portion, and bulging toward the outside in the width direction, a stress dispersion portion is provided in a region including the boundary portion of the tip end portion and the elastic contact piece, the stress dispersion portion has an outside narrow portion on the frontward side of the boundary portion and an inside narrow portion on the rearward side of the boundary portion, the outside narrow portion is configured such that the side edge of the press-fit terminal on the outside in the width direction enters the inside in the width direction, and the inside narrow portion is configured such that the peripheral edge of the opening portion bulges toward the outside in the width direction.

[0013] The press-fit terminal described above has a stress dispersion portion in a region including the boundary portion of the tip end portion and the elastic contact piece, the stress dispersion portion has an outside narrow portion on the frontward side of the boundary portion and an inside narrow portion on the rearward side of the boundary portion, the outside narrow portion is configured such that the side edge of the press-fit terminal on the outside in the width direction enters the inside in the width direction, and the inside narrow portion is configured such that the peripheral edge of the opening portion bulges toward the outside in the width direction. When the press-fit terminal is pressed into the through-hole of the circuit board to deform the elastic contact piece, stress is generated in the press-fit terminal in the vicinity of the elastic contact piece, but the wider the region of the metal material in which each elastic contact piece is continuous, the less the stress generated. Conversely, if the width of the region of the metal material in which each elastic contact piece is continuous is narrowed, the stress is easily distributed to the narrowed region. In the press-fit terminal, the boundary portion of the tip end portion and the elastic contact piece is a portion in which stress is easily concentrated when the press-fit terminal is pressed into the through-hole, but by providing the outside narrow portion on the frontward side of the boundary portion and the inside narrow portion on the rearward side of the boundary portion, the width of the elastic contact piece is intentionally narrowed at the positions of those narrow portions, so that stress is not only concentrated in the above-described boundary portion but also distributed to a wide region in the front-rear direction. By thus distributing the stress accompanying the deformation of the elastic contact piece to a wide range in the front-rear direction, the concentration of stress in the boundary portion is alleviated. If the stress generated is reduced, the mechanical load applied to the constituent material of the press-fit terminal is reduced, and large deformation is less likely to occur.

[0014] In the stress dispersion portion, the inner side narrow portion is provided on the inner side of the elastic contact piece, and does not interfere with or contact the through hole when the press-fit terminal is inserted into the through hole. The outer side narrow portion is also provided as a recessed structure in which the side edge on the outer side of the elastic contact piece enters the inner side, and thus it is difficult to interfere with or contact each portion of the through hole including the opening edge portion when the press-fit terminal is inserted. In this way, by providing the stress dispersion portion including the outer side narrow portion and the inner side narrow portion, it is possible to disperse the stress generated by deformation when the press-fit terminal is inserted into the through hole while suppressing interference or contact with the through hole. Furthermore, even if the inner side narrow portion is replaced by a recessed structure in which the side edge on the outer side of the press-fit terminal enters the inner side in the width direction on the rear side of the boundary portion of the tip end portion and the elastic contact piece, like the outer side narrow portion, the stress dispersion effect is obtained, but since this recessed structure is provided on the position on the outer side in the width direction than the outer side narrow portion by the convex shape of the elastic contact piece, it cannot be excluded that the end edge of the recessed structure collides with or hooks on the opening edge portion of the through hole when the press-fit terminal is inserted into the through hole. The press-fit terminal of the present application does not provide the recessed structure on the position on the rear side of the side edge on the outer side, but provides the outer side narrow portion on the position on the front side, and provides the inner side narrow portion on the inner side of the elastic contact piece, and thus it is possible to effectively suppress interference or contact with the through hole including collision or hooking at the end edge of the recessed structure.

[0015] [2] In the mode of the above [1], it is preferable that the distance in the front-rear direction between the bottom where the side edge in the outer side narrow portion enters the inner side in the width direction the most and the top where the peripheral edge in the inner side narrow portion bulges the outer side in the width direction the most converges within 50% of the bulging width of the pair of elastic contact pieces. In this case, by the outer side narrow portion and the inner side narrow portion, the position where the width of the region where the metal material is continuous narrows is provided at a position sufficiently close to the boundary portion of the tip end portion and the elastic contact piece where stress is easily concentrated when the press-fit terminal is inserted into the through hole. Therefore, the stress dispersion effect of the two narrow portions is highly obtained, and it is possible to effectively alleviate concentration of stress to the boundary portion of the tip end portion and the elastic contact piece.

[0016] [3] In the mode of the above [1] or [2], it is preferable that, in a state where the press-fit terminal is inserted into the through hole having an inner diameter smaller than the bulging width of the pair of elastic contact pieces, the position where stress is the largest due to deformation of the elastic contact piece in the region on the front side of the center in the front-rear direction of the elastic contact piece exists between the outer side narrow portion and the inner side narrow portion in the front-rear direction. In this case, the stress dispersion effect of the outer side narrow portion and the inner side narrow portion can be particularly highly obtained when the press-fit terminal is inserted into the through hole.

[0017] [4] In any of the aspects of [1] to [3] described above, it is preferable that, in the inner side narrow portion, the peripheral edge is convex toward the width direction outer side in a circular arc shape. Thus, the peripheral edge of the opening portion has a shape that is smoothly continuous including the portion in which the inner side narrow portion is provided.

[0018] [5] In any of the aspects of [1] to [4] described above, it is preferable that the stress dispersion portion does not have a protruding portion in which the side edge protrudes toward the width direction outer side. By not providing a protruding structure in the end edge on the width direction outer side of the press-fit terminal, it is particularly difficult to cause interference and contact with each portion of the through hole when the press-fit terminal is inserted into the through hole.

[0019] [Details of Embodiments of the Invention] Hereinafter, a press-fit terminal of an embodiment of the present invention will be described in detail using the drawings. In the present specification, terms such as symmetry, identity, straight line shape, circular arc shape, and the like with respect to shape or arrangement include not only geometrically strict concepts, but also concepts in which an error within a range generally permitted in connection terminals is included. The range of the error is, for example, about ±10% in length and angle.

[0020] [Outline of Structure of Press-Fit Terminal] Figure 1 The structure of a press-fit terminal 1 of an embodiment of the present invention is shown in FIG. 1. The press-fit terminal 1 is formed by punching a metal plate, and has an elongated shape as a whole. The kind of metal constituting the press-fit terminal 1 is not particularly limited, but a copper or copper alloy plate, or a plate in which a metal layer such as a tin layer is formed on the surface thereof can be appropriately used from the viewpoint of conductivity and the like.

[0021] The press-fit terminal 1 has a terminal portion 10 as a terminal portion at one end, and a connection portion 20 as a connection portion at the other end. Figure 1 As shown in FIG. 1, the press-fit terminal 1 has an inner side narrow portion 30 in which the width of the terminal portion 10 is narrower than the width of the connection portion 20. The inner side narrow portion 30 is provided in the vicinity of the terminal portion 10, and is provided in a position in which the terminal portion 10 is inserted into a through hole H provided in a circuit board B. Figure 3 4 As shown in FIG. 1, the press-fit terminal 1 has an inner side narrow portion 30 in which the width of the terminal portion 10 is narrower than the width of the connection portion 20. The inner side narrow portion 30 is provided in the vicinity of the terminal portion 10, and is provided in a position in which the terminal portion 10 is inserted into a through hole H provided in a circuit board B.

[0022] ​The terminal portion of the press-fit terminal 1 is configured as a needle eye type press-fit terminal, and integrally has a tip portion 10 at a front end, a base portion 20 at a rearward position from the tip portion 10, and a pair of elastic contact pieces 30 between the tip portion 10 and the base portion 20. The entire terminal portion configured of the tip portion 10, the base portion 20, and the pair of elastic contact pieces 30 has the same plate thickness, and is formed in the same plane. Further, as described above, the terminal portion is formed by punching a plate material, and has the same cross-sectional shape at each position in the thickness direction (the depth direction of the drawing) except for the joint between the surface and the back surface and the side surface.

[0023] The tip portion 10 is a position where the press-fit terminal 1 is inserted into the through-hole H of the circuit board B. In the illustrated mode, the tip portion 10 has a posture guide portion 11 extending linearly in the front direction from the front end of the elastic contact piece 30, and a position guide portion 12 gradually tapering toward the front direction from the front end of the posture guide portion 11. The posture guide portion 11 functions to straightly induce the posture of the press-fit terminal 1 with respect to the axis of the through-hole H, and the position guide portion 12 functions to induce the tip end of the press-fit terminal 1 to the center position of the through-hole H (see Figure 3 ). The base portion 20 is provided at a position separated rearward from the tip portion 10, and extends linearly in the front-rear direction.

[0024] Between the tip portion 10 and the base portion 20, the pair of elastic contact pieces 30 is provided, which connects the tip portion 10 and the base portion 20, and bulges toward the width direction outer side. The pair of elastic contact pieces 30 has a shape symmetrical with respect to the central axis of the press-fit terminal 1 in the front-rear direction. In the illustrated mode, each elastic contact piece 30 integrally and continuously has a first inclined portion 31, a contact portion 32, and a second inclined portion 33 in this order from the front to the rear. The first inclined portion 31 has a shape gradually bulging toward the width direction outer side from the front toward the rear. The contact portion 32 is a portion extending linearly in the front-rear direction. The second inclined portion 33 has a shape gradually tapering toward the width direction inner side from the front toward the rear.

[0025] Between the pair of elastic contact pieces 30, an opening portion 40 extending in the front-rear direction in a long hole shape is provided. That is, the pair of elastic contact pieces 30 is disposed opposite to each other in the width direction with the opening portion 40 interposed therebetween. In the illustrated mode, the peripheral edge 41 of the opening portion 40 is formed in the shape of the shape of the side edge (outer side edge) la along the width direction outer side of the pair of elastic contact pieces 30, and the width dimension of each elastic contact piece 30 in the front-rear direction is substantially the same (except for the position of a stress dispersing portion 50 described later).

[0026] In the press-fit terminal 1, a stress-dispersing portion 50 is provided in the region including the boundary between the top portion 10 and the elastic contact piece 30. The stress-dispersing portion 50 is provided as a part where a predetermined shape is formed on the outer edge 1a of the press-fit terminal 1 and the periphery 41 of the opening 40. Here, the boundary between the top portion 10 and the elastic contact piece 30 refers to the branch portion from the rear end of the top portion 10 where a pair of elastic contact pieces 30 branch out and bulge outward in the width direction; it refers to a position roughly corresponding to the front end of the opening 40 along the bulging shape of the elastic contact pieces 30. Detailed structure of the stress-dispersing portion 50 will be described later.

[0027] In its natural state without the press-fit terminal 1 inserted into the through hole H, the bulge width L of the elastic contact piece 30, i.e., the distance in the width direction between the outer edges 1a of the contact portions 32 of a pair of elastic contact pieces 30, is greater than the inner diameter L0 of the through hole H into which the press-fit terminal 1 is inserted (the maximum diameter when the inner diameter is distributed; the same applies below). Therefore, when the press-fit terminal 1 is inserted into the through hole H, it needs to be pressed in. When the press-fit terminal 1 is pressed into the through hole H, as... Figure 4 As shown, a pair of elastic contact pieces 30 are compressed and deformed inward in the width direction in a manner that brings them closer together. Furthermore, while the elastic contact pieces are in elastic contact with the inner wall surface H2 of the through hole H, the press-fit terminal 1 is electrically connected to the through hole H. As the elastic contact pieces 30 deform along with the press-fit terminal 1 being pressed in, tensile stress is applied at and near the boundary between the elastic contact pieces 30 and the top end portion 10, resulting in strain. The point where this stress and strain are greatest roughly corresponds to the boundary between the elastic contact pieces 30 and the top end portion 10. As explained in detail below, by providing a stress-dispersing portion 50 in the region including this boundary, the stress when the press-fit terminal 1 is inserted into the through hole H is dispersed.

[0028] <Details of the Stress Dispersion Section> As described above, in the press-fit terminal 1 of this embodiment, a stress dispersion portion 50 is provided in the region including the boundary portion of the top end portion 10 and the elastic contact piece 30. Figure 2 The image shows an enlarged view of the area near the stress dispersion portion 50. The stress dispersion portion 50 is configured such that a recessed structure is provided at the outer edge 1a of the press-fit terminal 1 and the periphery 41 of the opening portion 40, and has an outer narrow portion 51 and an inner narrow portion 52 in sequence from front to rear.

[0029] like Figure 2As shown, the outer side narrow portion 51 on the front side in the stress dispersion portion 50 is configured in the press-fit terminal 1 as a concave structure in which the outer side edge la enters (recedes, is recessed) to the inside in the width direction. In detail, in the outer side narrow portion 51, on the front side across the bottom portion (the portion that enters the most to the inside in the width direction), the outer side edge la of the press-fit terminal 1 enters to the inside from the front side toward the rear side at a steeper angle than the portion in front thereof. Further, on the rear side across the bottom portion, the outer side edge la enters to the inside from the rear side toward the front side at a steeper angle than the portion rearward thereof. The inclination of the outer side narrow portion 51 can be curved or straight, but is preferably smoothly continuous with the outer side edge la of the tip portion 10 and the elastic contact piece 30 on both the front and rear sides.

[0030] The outer side narrow portion 51 is formed at a position further forward than the boundary between the tip portion 10 and the elastic contact piece 30 of the press-fit terminal 1. That is, at least the bottom portion of the outer side narrow portion 51, and preferably the entire region of the outer side narrow portion 51, is formed further forward than the boundary. As described above, because the boundary between the tip portion 10 and the elastic contact piece 30 has a position that corresponds to the front end portion of the opening portion 40 along the convex shape of the elastic contact piece 30, the outer side narrow portion 51 need only be formed at a position at which at least the bottom portion is located slightly forward of the opening portion 40.

[0031] The inner side narrow portion 52 on the rear side in the stress dispersion portion 50 is configured in the press-fit terminal 1 as a convex structure in which the peripheral edge 41 of the opening portion 40 bulges (protrudes, is convex) to the outside in the width direction. In other words, the inner side narrow portion 52 is configured as a concave structure in which the inner side edge of each elastic contact piece 30 facing the opening portion 40 enters to the inside in the width direction of each elastic contact piece 30. In detail, in the inner side narrow portion 52, on the front side across the top portion (the portion that bulges the most to the outside in the width direction), the peripheral edge 41 of the opening portion 40 bulges to the outside from the front side toward the rear side. Further, on the rear side across the top portion, the peripheral edge 41 of the opening portion 40 bulges to the outside from the rear side toward the front side. The inclination of the inner side narrow portion 52 can be curved or straight, but is preferably smoothly continuous with the peripheral edge 41 of the opening portion 40 on the front and rear sides. The inner side narrow portion 52 is particularly preferably configured in such a way that the peripheral edge 41 of the opening portion 40 is in a circular arc shape that bulges to the outside in the width direction.

[0032] The inner narrow portion 52 is formed at a position rearward of the boundary between the top portion 10 of the pressure-fitting terminal 1 and the elastic contact piece 30. That is, at least the top of the inner narrow portion 52, preferably the entire area of ​​the inner narrow portion 52, is formed rearward of this boundary. As described above, since the boundary between the top portion 10 and the elastic contact piece 30 has a position that corresponds approximately along the convex shape of the elastic contact piece 30 to the front end of the opening 40, the inner narrow portion 52 only needs to be formed slightly behind the front end of the opening 40.

[0033] When inserting the press-fit terminal 1 of this embodiment into the through hole H, firstly, as follows: Figure 3 As shown, the press-fit terminal 1 is guided in a straight position along the central axis of the through hole H to the center of the through hole H via the top end 10. Furthermore, the first inclined portion 31 of the elastic contact piece 30 abuts against the opening edge H1 of the through hole H.

[0034] Here, if as Figure 7 As shown in the press-fit terminal 9', which has a stress-dispersing portion 95 formed only by a protruding shape, if the inner diameter L0 of the through hole H is small, the top of the protruding shape of the stress-dispersing portion 95 may come into contact with the opening edge H1 of the through hole H. Alternatively, even if contact is not achieved, interference may occur between the protruding shape of the stress-dispersing portion 95 and the through hole H. If such contact or interference occurs, it may be difficult to insert the press-fit terminal 9' further, or it may require a large force for insertion. However, in the press-fit terminal 1 of this embodiment, the stress-dispersing portion 50 has an outer narrow portion 51 as a concave structure, which is provided as the outer edge 1a of the press-fit terminal 1, and does not have a convex structure that protrudes outward in the width direction from the virtual outer edge V (the structure that inserts the outer edge 1a of the portion adjacent to the front and rear of the stress-dispersing portion 50 outwards respectively). Therefore, unlike the case with such a convex structure, the stress-dispersing portion 50 and the outer edge 1a simulated by the virtual outer edge V, such as Figure 6 Compared to the press-fit terminal 9 without a stress-dispersing portion, when the press-fit terminal 1 is inserted into the through hole H, the possibility of interference or contact with various parts of the through hole H cannot be increased. The inner narrow portion 52 is initially formed inside the elastic contact piece 30 and does not cause interference or contact with the through hole H. Thus, the stress-dispersing portion 50 of the press-fit terminal 1 in this embodiment, compared to… Figure 7 Compared to the stress-dispersing portion 95 formed by the protrusion shown, even when the inner diameter L0 of the through hole H is small, it is difficult for it to interfere or contact with the opening edge H1 of the through hole H. Therefore, the effects of such interference or contact can be reduced, and the insertion of the press-fit terminal 1 can be performed smoothly and with less force.

[0035] like Figure 3As shown, when the press-fit terminal 1 is further inserted from the state where the first inclined portion 31 of the elastic contact piece 30 abuts against the opening edge H1 of the through hole H, the outer edge 1a of the elastic contact piece 30 is pressed by the opening edge H1 of the through hole H, thereby causing the elastic contact piece 30 to gradually flex inward in the width direction while entering the interior of the through hole H. Furthermore, as... Figure 4 As shown, the contact portion 32 of the elastic contact piece 30 is pressed by the inner wall surface H2 of the through hole H. The elastic contact piece 30 deforms and is compressed inward in the width direction.

[0036] Thus, when the elastic contact piece 30 deforms and compresses inward in the width direction, stress is generated in the elastic contact piece 30. At this time, in the region where deformation first begins with the insertion of the press-fit terminal 1, namely the boundary between the top portion 10 and the elastic contact piece 30, the elastic contact piece 30 is subjected to a tensile force in the front-back direction, and stress concentration easily occurs near the outer edge 1a of this boundary. Stress concentration relates to applying excessive load to the metal material constituting the press-fit terminal 1, which may result in large strain.

[0037] exist Figure 6 In the conventional press-fit terminal 9 without a stress-dispersing portion, stress concentration easily occurs in the region of the boundary between the top portion 91 and the elastic contact piece 93. However, in the press-fit terminal 1 of this embodiment, which has a stress-dispersing portion 50 including an outer narrow portion 51 and an inner narrow portion 52, stress is dispersed over a wide range, and stress concentration is mitigated. As a stress concentration mitigation mechanism, the following mechanism can be considered: In the press-fit terminal 1, in regions where the metal material such as the elastic contact pieces 30 is continuous, the smaller the width, the more likely a larger stress will be generated. However, by providing the outer narrow portion 51 and the inner narrow portion 52 at the front and rear of the boundary between the top portion 10 and the elastic contact piece 30, a portion with a smaller width is intentionally provided, so that stress is easily distributed to that portion, and the stress is distributed over a wide range along the front-rear direction of the press-fit terminal 1. Therefore, the stress at each position along the front-rear direction is reduced. That is, by widely dispersing the stress in the front-rear direction, the concentration of stress in the narrow region of the boundary between the top portion 10 and the elastic contact piece 30 can be mitigated. As a result, it can suppress the large strain generated in the press-fit terminal 1 due to excessive load applied to the metal material.

[0038] exist Figure 8 In the middle, regarding terminal A Figure 6 The conventional press-fit terminal shown does not have a stress-dispersing portion, and terminal B is shown as... Figure 1The press-fit terminal shown having a stress dispersing portion including an outer side narrow portion and an inner side narrow portion shows results of actually analyzing a strain distribution. The analysis was performed for a terminal having the shape shown in the upper portion of the figure by an elastic-plastic analysis using a finite element method of computer aided engineering (CAE). In the figure, regarding the strain distribution of the middle portion, for the press-fit terminal inserted into the through-hole, the strain distribution is shown as a contour map, and the more the portion is shown in a dark color, the greater the strain generated. The main figure is a front view, and the figure shown in the frame is an enlarged view of the outer side edge portion. In the lower portion, as the generated strain, the maximum value of the strain in the above-described strain distribution is shown, and the case of terminal A is shown as 100%.

[0039] In the resulting strain distribution, in the case of terminal A not having a stress dispersing portion, as shown by arrow Al, the portion of the boundary of the tip end portion and the elastic contact piece is shown in a dark color significantly more than the surrounding portion, and a strain concentration is generated greatly. On the other hand, in the case of terminal B having a stress dispersing portion, in the region of the boundary of the tip end portion and the elastic contact piece and its vicinity, a portion where a strain concentration is not generated, compared to the case of terminal A, the strain is distributed to a significantly wider range. The maximum value of the strain shown by the depth of the display color also becomes smaller. That is, it is known that the strain is smaller at each portion compared to terminal A. From the results of the quantitative evaluation of the generated strain, in terminal B, the generated strain is reduced to 89% of terminal A. It is known that the strain distribution is highly correlated with the stress distribution, and the stress generated at each portion is smaller in the case of terminal B compared to the case of terminal A, and the stress concentration is alleviated. In this way, it is also confirmed by simulation that by forming a stress dispersing portion having an outer side narrow portion and an inner side narrow portion in the region including the boundary of the tip end portion of the press-fit terminal and the elastic contact piece, the stress concentration generated by the deformation at the time of insertion into the through-hole can be alleviated.

[0040] As described above, by forming a stress dispersing portion 50 having an outer side narrow portion 51 and an inner side narrow portion 52 in the region including the boundary of the tip end portion 10 of the press-fit terminal 1 and the elastic contact piece 30, it is possible to alleviate the stress concentration generated by the deformation at the time of insertion into the through-hole H while suppressing the interference or contact with each portion of the through-hole H including the opening edge portion H1. In recent years, there is a tendency for the through-hole H to be reduced in diameter, but from the necessity of securing sufficient holding force between the press-fit terminal 1 and the through-hole H, it is difficult to reduce the width of the press-fit terminal 1 in proportion to the reduction in diameter of the through-hole H, and the width of the press-fit terminal 1 is relatively large with respect to the inner diameter L0 of the through-hole H. However, if the press-fit terminal 1 of the present embodiment provided with the above-described stress dispersing portion 50 is used, even in a case where the width of the press-fit terminal 1 cannot be reduced relatively like that, it is possible to suppress the stress concentration while maintaining a state where it is difficult for the press-fit terminal 1 to interfere or contact with the small-diameter through-hole H.

[0041] In the stress dispersion portion 50, as a structure provided further rearward than the boundary portion between the tip end portion 10 and the elastic contact piece 30, instead of the inner side narrow portion 52, a recessed structure in which the outer side edge la of the press-fit terminal 1 enters inwardly can be considered to be provided similarly to the outer side narrow portion 51 (supposedly called an outer side rearward narrow portion). In this case, by the outer side rearward narrow portion, a region in which the width of the elastic contact piece 30 narrows is generated, and thus an effect of relaxing stress concentration is obtained. However, in this case, when the press-fit terminal 1 is inserted into the through-hole H having a small inner diameter Lo, the end edge of the rearward side from the bottom of the outer side rearward narrow portion comes into contact with the opening edge portion Hl of the through-hole H angularly, and thus the possibility of causing a collision or a hooking can be generated, although the possibility is low. On the other hand, in the press-fit terminal 1 of the present embodiment, the inner side narrow portion 52 is provided in the stress dispersion portion 50 instead of the outer side rearward narrow portion, and thus the possibility of causing such a collision or a hooking can be eliminated. Further, regarding the outer side rearward narrow portion, the possibility of causing such a collision or a hooking is supposed to be because the position at which the outer side rearward narrow portion is provided is the same position in the front-rear direction as the inner side narrow portion 52, that is, a position further rearward than the boundary portion between the tip end portion 10 and the elastic contact piece 30, and thus the position becomes a position outward in the width direction to some extent due to the bulging shape of the elastic contact piece 30. In contrast to this, the outer side narrow portion 51 is provided at a position further forward than the boundary portion between the tip end portion 10 and the elastic contact piece 30, that is, a position at which the outer side edge la does not bulge outward in the width direction to a large extent, and thus the possibility of causing such a collision or a hooking is considerably low.

[0042] As long as the outer side narrow portion 51 is provided on the forward side from the boundary portion between the tip end portion 10 and the elastic contact piece 30, and the inner side narrow portion 52 is provided on the rearward side from the boundary portion, the specific shape and position of the stress dispersion portion 50 are not particularly limited. However, the outer side narrow portion 51 and the inner side narrow portion 52 exist at positions close to each other to some extent across the boundary portion between the tip end portion 10 and the elastic contact piece 30, and thus the effect of stress dispersion of the stress dispersion portion 50 as a whole can be improved. For example, the distance between the bottom of the outer side narrow portion 51 and the top of the inner side narrow portion 52 in the front-rear direction of the press-fit terminal 1 converges within 50% of the bulging width L of the elastic contact piece 30, and further within 25%. However, even if the outer side narrow portion 51 and the inner side narrow portion 52 are too close, it is difficult to disperse stress along the front-rear direction to a wide range, and thus it is preferable that the front-rear direction positions do not overlap each other in the entire regions of the outer side narrow portion 51 and the inner side narrow portion 52, respectively. Further, as long as the positions of the outer side narrow portion 51 and the inner side narrow portion 52 are set as follows, the strain generated by the deformation of the elastic contact piece 30 in the region of the elastic contact piece 30 on the forward side from the center in the front-rear direction becomes the largest when the press-fit terminal 1 is inserted into the through-hole H (the position of the inner side narrow portion 52 is set to be on the forward side from the center in the front-rear direction of the elastic contact piece 30, and the position of the outer side narrow portion 51 is set to be on the rearward side from the center in the front-rear direction of the elastic contact piece 30). Figure 8Further preferably, as long as the position where the strain is the largest is located between the bottom of the outer narrow portion 51 and the top of the inner narrow portion 52, and the distance between the bottom of the outer narrow portion 51 and the top of the inner narrow portion 52 in the front-rear direction of the press-fit terminal 1 converges within 50%, further within 25%, of the bulging width L of the elastic contact piece 30.

[0043] In addition, the stress dispersing portion 50 can also have a structure other than the outer narrow portion 51 and the inner narrow portion 52. For example, a protrusion in which the outer edge la of the press-fit terminal 1 protrudes outward can be provided at a position in the front-rear direction between the outer narrow portion 51 and the inner narrow portion 52, particularly at or near the boundary between the tip end portion 10 and the elastic contact piece 30. By providing the protrusion, the width of the region in which the metal material is continuous is enlarged at the position of the protrusion, and the stress is dispersed in the width direction to a wide region, so the effect of mitigating the concentration of stress at the boundary between the tip end portion 10 and the elastic contact piece 30 is improved. In this case, the protrusion is provided in conjunction with the outer narrow portion 51 that is formed as a concave structure, so the protrusion alone does not constitute the stress dispersing portion. Therefore, even if the protrusion has the same protrusion height (the distance between the base portion and the top of the protrusion), the amount by which the protrusion protrudes outward in the width direction of the press-fit terminal 1 as a whole can be suppressed to be small, compared with the case in which the protrusion alone constitutes the stress dispersing portion as in Figure 7 Figure 7 Figure 8 The result is that, compared with the case in which the protrusion alone constitutes the stress dispersing portion as in Figure 2 the structure shown in FIG. 6, it is difficult to cause interference or contact with the through-hole H when the press-fit terminal 1 is inserted into the through-hole H. However, from the viewpoint of suppressing interference or contact with the through-hole H to be as small as possible, it is preferable that the stress dispersing portion 50 not have a protrusion that protrudes outward in the width direction from the outer edge la of the press-fit terminal 1. Even if such a protrusion is not provided, as shown in the simulation results of the terminal B of FIG. 7, a sufficiently high stress dispersing effect can be obtained with only the outer narrow portion 51 and the inner narrow portion 52. Furthermore, it can be considered that a convex structure that locally enlarges the width of the elastic contact piece 30, that is, a structure in which the peripheral edge 41 of the opening portion 40 enters inward in the width direction, is provided at the boundary between the tip end portion 10 and the elastic contact piece 30 or near thereto at the peripheral edge 41 of the opening portion 40, in order to improve the stress dispersing effect. However, if such a convex structure is provided, the convex structure is provided at a position in the front-rear direction or a direction close to the front-rear direction in the peripheral edge 41 of the opening portion 40 farther forward than the inner narrow portion 52, as shown in the structure of FIG. 6, so in practice it is difficult to secure a redundancy of space in which such a convex structure is provided. From the viewpoint of simplicity of structure, the stress dispersing portion 50 is also most preferably a structure in which only the outer narrow portion 51 and the inner narrow portion 52 are provided as structures for stress dispersing.​​

[0044] <Other modes> The press-fit terminal of the present application is not limited to the mode of the press-fit terminal 1 described in detail above, and as described above, it is sufficient that the stress dispersion portion 50 having the outer narrow portion 51 and the inner narrow portion 52 is provided in the region including the boundary portion of the tip end portion and the elastic contact piece.

[0045] For example, the overall shape of the press-fit terminal is not limited to Figure 1 the shape shown in the drawing. Figure 5 An example of a press-fit terminal of a mode in which the overall shape is different is shown in Fig. 9. In the press-fit terminal 1' of Figure 5 , the shape of the elastic contact piece 30' is different from Figure 1 the shape of the elastic contact piece 30. Here, the elastic contact piece 30' does not have the flat contact portion 32 extending in the front-rear direction, and has a shape in which the tip portion 35 at the center in the front-rear direction is bulged to the outer side in the width direction. In addition, the tip end portion 10' does not have a linear portion corresponding to the posture guide portion 11 of the mode of Figure 1 , but is formed in a simple shape in which the tip end becomes narrower and narrower. In this case as well, the stress dispersion portion 50 having the outer narrow portion 51 in the front side of the boundary portion (approximately the position corresponding to the front end of the opening portion 40 along the bulged shape of the elastic contact piece 30') of the tip end portion 10' and the elastic contact piece 30', and the inner narrow portion 52 in the rear side of the boundary portion is provided. The structures of the elements not described here are the same as those of the embodiment of the press-fit terminal 1 described above. Figure 1 Corresponding elements are denoted by corresponding reference numerals in the drawing.

[0046] In addition, in the mode of Figure 1 , 5 , the stress dispersion portion 50 is provided only in the region including the boundary portion of the tip end portion 10 (or 10'; the same hereinafter) and the elastic contact piece 30 (or 30'; the same hereinafter), but it is also possible to provide the stress dispersion portion in the region including the boundary portion of the base portion 20 and the elastic contact piece 30. According to Figure 8The strain distribution, the strain concentration also occurs at the position of the boundary portion of the base portion 20 of the terminal A and the elastic contact piece 30 and its vicinity, but by providing the stress dispersing portion in the area including the boundary portion of the base portion 20 and the elastic contact piece 30, the stress concentration of the rear side of the elastic contact piece 30 can be mitigated together with the stress concentration of the front side of the elastic contact piece 30. As the stress dispersing portion provided at the rear side of the elastic contact piece 30, any stress dispersing portion such as the stress dispersing portion composed of the protruding structure disclosed in Patent Document 3 can be used, but it is preferable that, like the stress dispersing portion 50 provided at the front side of the elastic contact piece 30 in the press-fit terminal 1 described above, it is a stress dispersing portion having an outer side narrow portion and an inner side narrow portion. In this case, the stress dispersing portion provided at the rear side only needs to have a shape in which the stress dispersing portion 50 at the front side is reversed in the front-rear direction. That is, it only needs to have the outer side narrow portion in which the outer side edge 1a enters the inner side in the width direction further to the rear side than the boundary portion of the base portion 20 and the elastic contact piece 30 (the position substantially corresponding to the rear end of the opening portion 40 along the convex shape of the elastic contact piece 30), and the inner side narrow portion in which the peripheral edge 41 of the opening portion 40 is convex to the outer side in the width direction further to the front side than the boundary portion.

[0047] Further, in the above, the eyelet type terminal is used as the press-fit terminal, but it is not limited thereto, and various press-fit shapes such as S type, N type, H type, M type, boat type, and the like can be applied.

[0048] The above describes the embodiments of the present application in detail, but the present application is not limited at all to the above-described embodiments, and various modifications can be made within the scope of the gist of the present application. Explanation of Reference Numerals

[0049] 1, 1', 9, 9' press-fit terminal 1a, 9a, 9'a outer side edge 10, 10, 91 tip portion 20, 92 base portion 30, 30', 93 elastic contact piece 31 first inclined portion 32 contact portion 33 second inclined portion 35 tip of the elastic contact piece 40, 94 opening portion 41 peripheral edge of the opening portion 50, 95 stress dispersing portion 51 outer side narrow portion 52 inner side narrow portion B circuit board H through hole H1 opening edge portion H2 inner wall surface L convex width of elastic contact piece L0 inner diameter of through hole V virtual outer edge

Claims

1. A press-fit terminal inserted into a through-hole provided in a circuit board, wherein a direction of insertion of the press-fit terminal with respect to the through-hole is taken as a front direction, an opposite direction thereof is taken as a rear direction, and a direction orthogonal to the direction of insertion is taken as a width direction, the press-fit terminal includes: a tip end portion located at a front end; a base portion located at a rearward direction from the tip end portion; and a pair of elastic contact pieces disposed opposite to each other with an opening portion interposed therebetween, located between the tip end portion and the base portion, and bulging toward an outer side in the width direction, a stress dispersion portion is provided in a region including a boundary portion between the tip end portion and the elastic contact pieces, the stress dispersion portion has an outer side narrow portion on a frontward direction side from the boundary portion and an inner side narrow portion on a rearward direction side from the boundary portion, the outer side narrow portion is configured such that a side edge of the press-fit terminal on an outer side in the width direction enters an inner side in the width direction, and the inner side narrow portion is configured such that a peripheral edge of the opening portion bulges toward an outer side in the width direction.

2. The press-fit terminal according to claim 1, wherein a distance in the front-rear direction between a bottom portion at which the side edge in the outer side narrow portion enters the inner side in the width direction the most and a top portion at which the peripheral edge in the inner side narrow portion bulges toward the outer side in the width direction the most converges within 50% of a bulging width of the pair of elastic contact pieces.

3. The press-fit terminal according to claim 1 or claim 2, wherein in a state in which the press-fit terminal is inserted into a through-hole having an inner diameter smaller than a bulging width of the pair of elastic contact pieces, a position at which stress generated by deformation of the elastic contact pieces is the largest in a region of the elastic contact pieces on a frontward direction side from a center in the front-rear direction exists between the outer side narrow portion and the inner side narrow portion in the front-rear direction.

4. The press-fit terminal according to claim 1 or claim 2, wherein in the inner side narrow portion, the peripheral edge bulges toward the outer side in the width direction in a circular arc shape.

5. The press-fit terminal according to claim 1 or claim 2, wherein the stress dispersion portion does not have a protruding portion in which the side edge protrudes toward the outer side in the width direction.

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