Press-fit terminal and semiconductor device

Abstract

To satisfy performance required for a press-fit terminal in the press-fit terminal and a semiconductor device.SOLUTION: In one aspect, a press-fit terminal (1) includes a base portion (20), and a pair of branch portions (1112,) that are bifurcated from root portions (11b, 12b) on the base portion (20) side while being separated from each other, are curved such that tips (11a, 12a) approach each other, and are press-fitted into an insertion hole (111) in a press-fitting direction (D2) to be elastically deformed. Each of the pair of branch portions (1112) has a hardened region (A) located closer to the root portion (D1, L1) than the maximum length (12b) portion in the deformation direction (11b) before the press-fitting into the insertion hole (111).SELECTED DRAWING: Figure 4B

Description

[Technical Field]

[0001] The present invention relates to a press-fit terminal and a semiconductor device including the press-fit terminal. [Background technology]

[0002] Conventionally, semiconductor devices have circuit boards on which semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) are mounted, and are used in inverter devices, etc. Such semiconductor devices sometimes use press-fit terminals that are press-fit into insertion holes such as through-holes in the board and elastically deform (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-126786 Summary of the Invention [Problem to be solved by the invention]

[0004] If the press-fit terminal has angular edges on the cross section perpendicular to the press-fit direction, it will come into point contact with the inner wall when pressed into the insertion hole of the board, causing damage to the insertion hole, such as scraping off the plating layer of the insertion hole. On the other hand, if the press-fit terminal has a curved edge on the cross section, even if damage to the insertion hole can be prevented, the insertion load may fall below the lower limit specification value.

[0005] An object of the present invention is to provide a press-fit terminal and a semiconductor device that can satisfy the performance required of a press-fit terminal. [Means for solving the problem]

[0006] In one aspect, a press-fit terminal comprises a base portion and a pair of branch portions that branch into two while being spaced apart from a root portion on the base portion side, curve so that their tips approach each other, and are elastically deformed when press-fitted into an insertion hole in a press-fitting direction, the pair of branch portions having a hardened region located closer to the root portion than a maximum length portion in the deformation direction before press-fitting into the insertion hole.In another aspect, a press-fit terminal comprises a base portion and a pair of branch portions that branch into two while being spaced apart from a root portion on the base portion side, curve so that their tips approach each other, and are elastically deformed, the pair of branch portions having a hardened region located closer to the root portion than a maximum length portion at which the distance between them is greatest.

[0007] In another aspect, a semiconductor device includes the press-fit terminal and a laminated substrate on which a semiconductor element electrically connected to the press-fit terminal is mounted. [Effects of the Invention]

[0008] According to the above aspect, the press-fit terminal and the semiconductor device can satisfy the performance required for the press-fit terminal. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a semiconductor device according to an embodiment; [Figure 2] 1 is a front view showing a press-fit terminal according to an embodiment of the present invention; [Figure 3] 10A to 10C are explanatory diagrams showing an example of a method for forming a hardened region according to an embodiment. [Figure 4A] FIG. 1 is a front view (part 1) for explaining insertion of a board (press-fitting of a press-fit terminal) in one embodiment. [Figure 4B] FIG. 10 is a front view (part 2) illustrating insertion of a board (press-fitting of a press-fit terminal) in one embodiment. [Figure 5] FIG. 10 is a plan view showing an arc-shaped portion of an elastically deforming portion in one embodiment. [Figure 6] FIG. 10 is a plan view showing a rounded surface portion of an elastically deforming portion in a modified example. [Figure 7] 10 is an explanatory diagram showing the relationship between the insertion load of the press-fit terminal and the diameter of the through-hole. FIG. [Figure 8A] 10A and 10B are diagrams illustrating simulation results of stress distribution on the inner wall of a through-hole when a press-fit terminal is press-fitted in one embodiment. [Figure 8B] 10A and 10B are diagrams showing simulation results of stress distribution on the inner wall of a through-hole when a press-fit terminal is press-fitted in a comparative example. [Figure 9] FIG. 10 is a plan view showing a corner region of an elastically deforming portion in a comparative example. [Figure 10] 10 is an explanatory diagram showing the relationship between the insertion load of a press-fit terminal and the diameter of a through-hole in a comparative example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] A press-fit terminal and a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiment described below, and can be modified and implemented as appropriate within the scope of the present invention.

[0011] FIG. 1 is a cross-sectional view showing a semiconductor device 100, and FIG. 2 is a front view showing a press-fit terminal 1. As shown in FIG.

[0012] 1 and 2, and FIGS. 4A to 6 and 8A to 9 described later, the press-fitting direction D2 of the press-fit terminal 1 is defined as the positive Z direction, and of the X and Y directions that are perpendicular to the Z direction and perpendicular to each other, the deformation direction D1 of the elastically deforming portion 10 of the press-fit terminal 1 is defined as the X direction. In some cases, the X direction may be referred to as the left-right direction, the Y direction as the front-back direction, and the Z direction as the up-down direction. These directions are terms used for convenience of explanation, and the corresponding relationships between the X, Y, and Z directions will change depending on the posture of the press-fit terminal 1 and the semiconductor device 100, etc.

[0013] 1 is applied to a power conversion device such as an inverter device for an industrial or automotive motor, together with a cooler (not shown) disposed below the metal base 150. In the following explanation, detailed explanations of configurations, functions, operations, assembly methods, etc. that are identical to or similar to those of known press-fit terminals 1 and semiconductor device 100 will be omitted. Note that press-fit terminal 1 can also be used for applications other than semiconductor device 100, such as wiring connections and component connections in electrical equipment, electronic equipment, communication equipment, etc.

[0014] As shown in FIG. 2, the press-fit terminal 1 includes an elastically deformable portion 10 and a base portion 20. For example, the press-fit terminal 1 is made of a metal material such as copper, copper alloy, brass, or stainless steel, to which a first plating layer P1 (see FIG. 3(a)) is applied. The first plating layer P1 is, for example, Sn plating. It is preferable that the first plating layer P1 is removed from the tips 11a, 12a of the first branch piece 11 and the second branch piece 12 by punching or the like to prevent whiskers from forming in the first plating layer P1.

[0015] The elastically deforming portion 10 has a first branched piece 11 and a second branched piece 12, which are an example of a pair of branched portions. The first branched piece 11 and the second branched piece 12 are bifurcated from root portions 11b, 12b on the base portion 20 side while being spaced apart from each other in the X direction, and their tips 11a, 12a in the press-fitting direction D2 into the through-hole 111 are curved so as to approach each other, and are press-fitted into the through-hole 111 and elastically deformed. The elastically deforming portion 10 can also be called a press-fit portion, and the first branched piece 11 and the second branched piece 12 can also be called a U-shaped portion, a crab-claw shaped portion, a crab-scissors shaped portion, or the like.

[0016] The elastically deforming portion 10 (first branch piece 11 and second branch piece 12) may have other shapes, such as a shape in which the tip 11a of the first branch piece 11 and the tip 12a of the second branch piece 12 are integrated and open at the center. Furthermore, the elastically deforming portion 10 is not limited to being provided at the end on the positive side in the Z direction of the press-fit terminal 1, and may be, for example, a tip portion that extends in the Z direction further toward the positive side in the Z direction than the portion where the tip 11a of the first branch piece 11 and the tip 12a of the second branch piece 12 are integrated, as described above. In this case, the tip portion becomes a non-elastically deforming portion that does not elastically deform.

[0017] Consider a comparative example shown in FIG. 9 , in which the four corner regions 11f, 12f located on the periphery of the cross section of the first branch piece 11 and the second branch piece 12 perpendicular to the press-fitting direction D2 and in contact with the through-hole 111 are angular. In this case, as shown by the squares in FIG. 10 , the press-fit load during insertion (press-fitting) of the press-fit terminal 1 into the through-hole 111 decreases as the diameter of the through-hole 111 increases. However, the press-fit load exceeds the lower limit specification value and satisfies the standard unless the diameter of the through-hole 111 is too large. This lower limit specification value is set, for example, to ensure product reliability by preventing the press-fit terminal 1 from coming off the board 110 (through-hole 111) due to vibration or impact. However, because the four corner regions 11f, 12f are angular, the corner regions 11f, 12f come into near-point contact with the inner wall of the through-hole 111 when the press-fit terminal 1 is press-fitted into the through-hole 111. This causes damage to the through-hole 111 and the press-fit terminal 1, such as scraping away the plating layer (not shown) of the through-hole 111 or the first plating layer P1 of the press-fit terminal 1. This reduces the remaining plating thickness of the plating layer (not shown) of the through-hole 111 or the first plating layer P1 of the press-fit terminal 1, and so the remaining plating thickness no longer meets the standard.

[0018] The corner regions 11f and 12f are four regions: an end (corner region 12f) on the positive side in the X direction (deformation direction D1) and in the positive side in the Y direction (width direction D4 perpendicular to the press-fit direction D2 and deformation direction D1), an end (corner region 12f) on the positive side in the X direction and in the negative side in the Y direction, an end (corner region 11f) on the negative side in the X direction and in the positive side in the Y direction, and an end (corner region 11f) on the negative side in the X direction and in the negative side in the Y direction. Because the elastically deforming portion 10 includes the first branch piece 11 and the second branch piece 12, two corner regions 11f and 12f are formed in the first branch piece 11 and two corner regions 11f and 12f are formed in the second branch piece 12. In addition, in a cross-sectional view perpendicular to the press-fit direction D2, the four corner regions 11f, 12f can also be considered to be regions connecting the side in the X direction (deformation direction D1) and the side in the Y direction (direction perpendicular to the X direction) of the press-fit terminal 1. In other words, in a cross-sectional view perpendicular to the press-fit direction D2, the four corner regions 11f, 12f can be considered to be the four corner regions of a rectangular region (or approximately rectangular region) formed by the first branch piece 11, the second branch piece 12, and the region sandwiched between them.

[0019] To prevent the plating layer (not shown) of the through-hole 111 and the first plating layer P1 of the press-fit terminal 1 from being scraped off, the first branch piece 11 and the second branch piece 12 preferably have arc-shaped portions 11c, 12c with a center of curvature on the center side of the through-hole 111 at both ends in the deformation direction D1 in a cross section (see the plan view of FIG. 5 ) perpendicular to the press-fit direction D2 when press-fitted. These arc-shaped portions 11c, 12c preferably have a radius of curvature that is the same as or close to the radius of the through-hole 111 to fit into the through-hole 111. The arc-shaped portions 11c, 12c are provided, for example, over the entire elastically deforming portion 10 in the press-fit direction D2, but may be provided on at least a portion of the elastically deforming portion 10 that can come into contact with the through-hole 111 (a portion that has a larger diameter than the through-hole 111 before press-fitting). The elastically deformable portion 10 having the arc-shaped portions 11c and 12c can be formed by any molding method or pressing method.

[0020] In this way, when the first branch piece 11 and the second branch piece 12 have the arc-shaped portions 11c, 12c, it is possible to prevent the plating layer (not shown) of the through-hole 111 and the first plating layer P1 of the press-fit terminal 1 from being scraped. However, as shown by the open circle in Fig. 10, the insertion load when inserting (press-fitting) the press-fit terminal 1 into the through-hole 111 falls below the lower limit specification value. Note that the insertion load tends to decrease as the diameter of the through-hole 111 increases, but falls below the lower limit specification value regardless of the diameter of the through-hole 111.

[0021] Therefore, the first branched piece 11 and the second branched piece 12 preferably have a hardened region A shown in FIG. 2 so that the insertion load exceeds the lower limit specification value. This hardened region A is located closer to the root portions 11b and 12b than the maximum length (L) portion in the deformation direction D1 before press-fitting into the through-hole 111. This maximum length (L) portion can also be said to be the portion where the separation distance between the first branched piece 11 and the second branched piece 12 is greatest. Furthermore, the hardened region A is preferably located closer to the root portions 11b and 12b than the position of the through-hole 111 after press-fitting (see FIG. 4B ) in the press-fitting direction D2. Here, even when the hardened region A is located both closer to the root portions 11b and 12b and closer to the tips 11a and 12a than the maximum length (L) portion, it can be said that the hardened region A is located closer to the root portions 11b and 12b than the maximum length (L) portion.

[0022] Furthermore, the hardened region A is preferably provided on both end faces (the front face and the rear face behind it shown in FIG. 2) of the first branch piece 11 and the second branch piece 12 in the width direction D4 (Y direction) shown in FIG. 5, which is perpendicular to the press-fitting direction D2 (Z direction) and the deformation direction D1 (X direction). However, the hardened region A may be provided on only one of the front face and the rear face of the first branch piece 11 and the second branch piece 12. Furthermore, the length of the hardened region A in the Z direction is preferably 20% or less of the length of the elastically deforming portion 10 in the Z direction.

[0023] As shown in FIGS. 3( a) and 3(b), the hardened region A is pressed by a tool T having multiple protrusions Ta, forming multiple recesses Aa. This results in a higher yield strength in the hardened region A than in other regions of the first branch piece 11 and the second branch piece 12. That is, the hardened region A has locally higher strength than the other regions of the first branch piece 11 and the second branch piece 12, making it less likely to bend when pressed into the through-hole 111. Thus, the hardened region A is preferably formed by plastic processing. While the hardened region A can also be formed by other techniques, such as sandblasting, forming the hardened region A by pressing using the tool T reduces the likelihood of distortion within the first branch piece 11 and the second branch piece 12. Furthermore, the hardened region A is preferably formed after masking its periphery to prevent processing debris scattered around the hardened region A from adhering to the first branch piece 11 and the second branch piece 12.

[0024] The tool T is made of a material having a higher hardness than the press-fit terminal 1, such as a cemented carbide containing tungsten. For example, in the example shown in FIG. 3(d) in plan view (when viewed in the pressure direction), the protrusions Ta of the tool T have a diamond shape in plan view so as to form diamond-shaped recesses Aa arranged in a staggered pattern. The protrusions Ta of the tool T may have, for example, a polygonal pyramid shape such as a square pyramid, a cone shape, a polygonal prism shape with a tapered tip, or a cylinder shape with a tapered tip, as long as they match the shape of any recesses Aa in the hardened region A.

[0025] As shown in FIG. 3(c), after the hardened region A is formed, a second plating layer P2 is preferably formed on the surface of the hardened region A (an example of a portion of the surface including the hardened region A) on the first plating layer P1. The second plating layer P2 is preferably made of a material with higher rigidity than the first plating layer P1 (e.g., Sn plating), such as nickel plating. The second plating layer P2 may be formed only in the hardened region A, or may be formed only on the same surfaces of the first branch piece 11 and the second branch piece 12 as the surfaces on which the hardened region A is formed. As described above, the second plating layer P2 is preferably made of a material with higher rigidity than the first plating layer P1. However, even if the second plating layer P2 is made of the same material (or a material with similar rigidity) as the first plating layer P1 or a material with lower rigidity than the first plating layer P1, the strength of the hardened region A can be improved by providing the second plating layer P2.

[0026] As shown in FIG. 6 (modification), the elastically deforming portion 10 may have, instead of the arc-shaped portions 11c and 12c, rounded surface-shaped portions 11d and 12d, which are located on the periphery of a cross section perpendicular to the press-fitting direction D2 and have rounded chamfered shapes, in each (at least one) of four corner regions 11f and 12f (see FIG. 9) that contact the through-hole 111. The rounded surface-shaped portions 11d and 12d may be provided, for example, over the entire elastically deforming portion 10 in the press-fitting direction D2, but may only be provided on at least a portion of the elastically deforming portion 10 that can contact the through-hole 111. The elastically deforming portion 10 having the rounded surface-shaped portions 11d and 12d may be formed by performing R-chamfering as a post-process, or may be formed by any molding method, pressing method, or the like.

[0027] The base portion 20 is provided integrally with the elastically deforming portion 10 on the negative side of the elastically deforming portion 10 in the Z direction. In the example of Fig. 1, the base portion 20 has an L-shaped plate shape. Note that, like the shape of the elastically deforming portion 10, the shape of the base portion 20 is not particularly limited.

[0028] The semiconductor device 100 shown in FIG. 1 includes a plurality of press-fit terminals 1, a substrate 110, a semiconductor element 120, a case 130, a laminated substrate 140, a metal base 150, and wires 161-163.

[0029] The substrate 110 is disposed above the case 130. The substrate 110 is provided with a through-hole 111 for electrical connection, which is an example of an insertion hole into which the elastically deforming portion 10 is press-fitted. A plating layer (not shown) made of, for example, copper is formed on the surface of the through-hole 111. The substrate 110 is an example of a member electrically connected to the press-fit terminal 1.

[0030] The semiconductor element 120 is bonded onto the first conductor plate 141 by a conductive bonding material (not shown) such as solder. The semiconductor element 120 is composed of, for example, an IGBT element, which is a switching element, or an RC (Reverse Conducting)-IGBT element, which integrates the IGBT element with a diode element, such as an FWD (Free Wheeling Diode) element, connected in anti-parallel to the switching element. The switching element and diode element in the semiconductor element 120 are not limited to a Si substrate, and may be formed on a semiconductor substrate using a wide bandgap semiconductor, such as SiC (silicon carbide) or GaN (gallium nitride). This type of semiconductor element 120 has electrodes (not shown) on its bottom and top surfaces. The electrodes on the top surface of the semiconductor element 120 are electrically connected to the wirings 161 and 163 by a conductive bonding material. 1 (negative side in the Y direction) via wiring 163, and is connected to the press-fit terminal 1 on the other side (positive side in the Y direction) via wiring 161, 162 and a second conductor plate 142. The press-fit terminal 1 can be used as any terminal, such as a main terminal such as an output terminal or an input terminal (P terminal and N terminal), or a control terminal.

[0031] The case 130 has, for example, a rectangular cylindrical shape with a central axis in the Z direction, and houses the semiconductor element 120 and the like. The case 130 is formed using an insulating resin material such as PPS (Poly Phenylene Sulfide) or PA (Poly Amide). The case 130 is adhered to the upper surface of the metal base 150.

[0032] The case 130 is integrally molded with the press-fit terminals 1, with both ends of the press-fit terminals 1 exposed. The semiconductor element 120, first conductive plate 141, second conductive plate 142, etc. inside the case 130 are sealed with a sealing material M. This sealing material M is, for example, epoxy resin, silicone gel, etc. It is also preferable that a cover be provided above the sealing material M, covering the entire XY plane of the hollow portion of the case 130.

[0033] The laminated substrate 140 has a semiconductor element 120 mounted thereon that is electrically connected to the press-fit terminal 1, and includes a first conductive plate 141, a second conductive plate 142, a third conductive plate 143, and an insulating plate 144. The first conductive plate 141 and the second conductive plate 142 are provided on the upper surface of the insulating plate 144, and the third conductive plate 143 is provided on the lower surface of the insulating plate 144. The laminated substrate 140 is, for example, a DCB (Direct Copper Bonding) substrate or an AMB (Active Metal Brazing) substrate.

[0034] The first conductor plate 141 and the second conductor plate 142 are members that function as wiring members in the inverter circuit, and are formed of, for example, a metal plate or metal foil made of copper, aluminum, etc. The first conductor plate 141 and the second conductor plate 142 may also be called a conductor layer, a conductive layer, a conductor pattern, a wiring pattern, etc.

[0035] The third conductor plate 143 is a member that functions as a heat conduction member that conducts heat generated in the inverter circuit to the metal base 150, and is formed of, for example, a metal plate or metal foil such as copper or aluminum. The third conductor plate 143 is joined to the metal base 150 by a joining material J such as solder. The third conductor plate 143 may also be called a heat dissipation layer, heat dissipation plate, conductor pattern, heat dissipation pattern, etc.

[0036] The insulating plate 144 may be a ceramic substrate formed of a ceramic material such as aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), or a composite material of aluminum oxide (Al2O3) and zirconium oxide (ZrO2). The insulating plate 144 may be, for example, a substrate formed by molding an insulating resin such as epoxy resin, a substrate formed by impregnating a base material such as glass fiber with an insulating resin, or a substrate formed by coating the surface of a flat metal core with an insulating resin.

[0037] The metal base 150 is a rectangular plate-shaped member. The metal base 150 functions as a heat-conducting member that conducts heat generated by the semiconductor element 120 to a cooler (not shown), and is formed of a metal plate such as a copper plate or an aluminum plate. The metal base 150 and the cooler are connected via a heat-conducting material such as thermal grease or a thermal compound. The metal base 150 may also function as a cooler.

[0038] The wiring 161 to 163 are, for example, lead frames or wires. The wiring 161 connects the semiconductor element 120 and the second conductor plate 142. The wiring 162 connects the second conductor plate 142 and the base portion 20 of the press-fit terminal 1 on the positive side in the Y direction. The wiring 163 connects the semiconductor element 120 and the base portion 20 of the press-fit terminal 1 on the negative side in the Y direction.

[0039] In the above description, the press-fit terminal 1 is disposed in the semiconductor device 100. However, as mentioned above, the use of the press-fit terminal 1 is not limited to the semiconductor device 100, and the press-fit terminal 1 may be used in any device. Furthermore, the circuit of the semiconductor device 100 includes a switching element, a diode element, and the like inside the semiconductor element 120. However, the semiconductor device 100 may constitute any circuit, such as a single-phase voltage-type half-bridge inverter circuit, a single-phase full-bridge inverter circuit, or a three-phase AC inverter circuit. Furthermore, the above description of the semiconductor device 100 is merely an example, and the semiconductor device 100 may be any device that includes a laminated substrate 140 on which a semiconductor element 120 electrically connected to the press-fit terminal 1 is mounted.

[0040] Next, the insertion of the substrate 110 (press-fitting of the press-fit terminal 1) will be described with reference to the front views of FIGS. 4A and 4B.

[0041] First, as shown in FIG. 4A , for example, a manufacturing apparatus for a semiconductor device 100 positions the X- and Y-direction positions of a plurality of through-holes 111 of a substrate 110 to the X- and Y-direction positions of a plurality of press-fit terminals 1, and then moves the substrate 110 in the negative Z-direction (substrate insertion direction D3). This causes the elastically deforming portion 10 exposed upward from the case 130 shown in FIG. 1 to enter the cylindrical through-hole 111. Before the elastically deforming portion 10 elastically deforms, the maximum length L (see FIG. 2 ) of the elastically deforming portion 10 in the deformation direction D1 (X-direction) is greater than the inner diameter of the through-hole 111. Therefore, only the tips 11 a and 12 a of the first branch piece 11 and the second branch piece 12 enter the through-hole 111. Note that instead of moving the substrate 110 in the negative Z-direction as described above, the press-fit terminal 1 (elastically deforming portion 10) may be press-fitted by moving the press-fit terminal 1 (case 130) in the positive Z-direction.

[0042] When the board 110 is pressed in the board insertion direction D3, both ends of the first branch piece 11 and the second branch piece 12 in the deformation direction D1 come into contact with the inner circumferential wall of the through-hole 111, applying contact pressure to the first branch piece 11 and the second branch piece 12, causing the elastic deformation portion 10 to elastically deform so as to be compressed in the deformation direction D1. When the elastic deformation portion 10 deforms, the tips 11a, 12a of the first branch piece 11 and the second branch piece 12 elastically deform so as to approach each other. In other words, the elastic deformation occurs when the press-fit terminal 1 is press-fitted into the through-hole 111 in the press-fit direction D2. Furthermore, as the press-fit terminal 1 is press-fitted into the through-hole 111, the first branch piece 11 and the second branch piece 12 deform in the deformation direction D1 perpendicular to the press-fit direction D2, bringing them closer to each other.

[0043] As shown in Figure 4B, when the insertion of the board 110 in the board insertion direction D3 is completed, the elastically deforming portion 10 is further compressed in the deformation direction D1, and the tip 11a of the first branch piece 11 and the tip 12a of the second branch piece 12 come into contact with each other. In this state, the elastic force of the elastically deforming portion 10 is strong, so even if the elastically deforming portion 10 is pulled in the direction opposite to the press-fit direction D2, it is difficult to remove. This ensures an electrical connection between the press-fit terminal 1 and the through-hole 111, making it possible to mount the board 110 without soldering.

[0044] As shown in Figure 7, if the first branch piece 11 and the second branch piece 12 (the first branch piece 11 and the second branch piece 12 having arc-shaped portions 11c, 12c as shown in Figure 5) do not have a hardened region A (shown by a white circle), the insertion load when inserting (pressing) the press-fit terminal 1 into the through hole 111 will fall below the lower limit specification value regardless of the diameter of the through hole 111, as described above with reference to Figure 10.

[0045] In contrast, when a hardened region A is provided in the first branch piece 11 and the second branch piece 12 (the first branch piece 11 and the second branch piece 12 having arc-shaped portions 11c, 12c as shown in Figure 5) as in this embodiment (shown by a shaded circle), the insertion load when inserting (pressing) the press-fit terminal 1 into the through hole 111 tends to decrease as the diameter of the through hole 111 increases, but exceeds the lower limit specification value and meets the standard regardless of the diameter of the through hole 111.

[0046] In this way, by providing hardened region A, it is possible to increase the insertion load without changing the length, width, thickness, shape, or diameter of through hole 111 of press-fit terminal 1. Here, the reason why the insertion load increases by providing hardened region A is that, as shown in Fig. 8A (see part VIII of Fig. 4B ), when elastically deforming portion 10 (first branch piece 11 on one side is shown by a two-dot chain line) provided with hardened region A is press-fit, the reaction force of hardened region A increases, causing large stress portion S1, medium stress portion S2, and small stress portion S3 of through hole 111 to concentrate at the upstream end (negative end in the Z direction) in press-fit direction D2, thereby increasing the contact load after press-fitting.

[0047] In contrast, when the first branch piece 11 is press-fitted without the hardened region A, the small stress portion S3 of the through-hole 111 is dispersed in the press-fitting direction D2, and the large stress portion S1 and the medium stress portion S2, which are larger than the small stress portion S3, are not generated, as shown in Fig. 8B (comparative example). Therefore, the insertion load does not become large.

[0048] In the above description, an example was given in which hardened region A is provided so that the insertion load of press-fit terminal 1 exceeds the lower limit specification value shown in Fig. 7, but providing hardened region A is also effective for increasing the pull-out load (retention force) of press-fit terminal 1. Furthermore, if the relationship between press-fit terminal 1 and through-hole 111 is such that the plating layer (not shown) of through-hole 111 and first plating layer P1 of press-fit terminal 1 are not easily scraped, the insertion load and pull-out load will be small, so it is effective to select the area and strength of hardened region A according to the required performance. In this case, the length, width, thickness, shape, and diameter of through-hole 111 of press-fit terminal 1 may also be adjusted as appropriate.

[0049] The press-fit terminal 1 according to the present embodiment described above includes a pair of branched portions, namely, first branched piece 11 and second branched piece 12, and a base portion 20. First branched piece 11 and second branched piece 12 are bifurcated from root portions 11b and 12b on the base portion 20 side while being spaced apart from each other, and tip portions 11a and 12a are curved so as to approach each other. First branched piece 11 and second branched piece 12 are press-fitted into a through-hole 111 (an example of an insertion hole) in a press-fitting direction D2 and are elastically deformed. First branched piece 11 and second branched piece 12 have a hardened region A located closer to the root portions 11b and 12b than the portion of maximum length L1 in the deformation direction D1 before press-fitting into the through-hole 111. From another perspective, the press-fit terminal 1 includes a first branch piece 11 and a second branch piece 12, which are an example of a pair of branch portions, and a base portion 20. The first branch piece 11 and the second branch piece 12 are bifurcated from root portions 11b, 12b on the base portion 20 side while being spaced apart from each other, and the tips 11a, 12a are curved so as to approach each other, with a hardened region A located closer to the root portions 11b, 12b than the maximum length L1 portion where the separation distance is greatest. From another perspective, elastic deformation occurs when the press-fit terminal 1 is press-fitted into the through-hole 111 in a press-fit direction D2. Due to this press-fitting, the first branch piece 11 and the second branch piece 12 deform in a deformation direction D1 perpendicular to the press-fit direction D2, thereby reducing the distance between them. The semiconductor device 100 according to this embodiment also includes the press-fit terminal 1 and a laminated substrate 140 on which a semiconductor element 120 electrically connected to the press-fit terminal 1 is mounted.

[0050] As a result, even if the relationship between the press-fit terminal 1 and the through-hole 111 is such that, for example, the plating layer of the through-hole 111 or the first plating layer P1 of the press-fit terminal 1 is less likely to be scraped off and the insertion load of the press-fit terminal 1 into the through-hole 111 is reduced, by providing the hardened region A in the press-fit terminal 1, it is possible to increase the insertion load without changing the length, width, thickness, shape of the press-fit terminal 1 or the diameter of the through-hole 111. Therefore, according to this embodiment, the performance required of the press-fit terminal 1 can be satisfied.

[0051] In addition, in this embodiment, when the first branch piece 11 and the second branch piece 12 are pressed in, they have arc-shaped portions 11c, 12c at both ends of the deformation direction D1 in a cross section perpendicular to the pressing-in direction D2, with the center of curvature being on the center side of the through hole 111.

[0052] This prevents the plating layer of the through-hole 111 and the first plating layer P1 of the press-fit terminal 1 from being scraped off when the press-fit terminal 1 is press-fitted into the through-hole 111, compared to when the first branch piece 11 and the second branch piece 12 have angular edges (see corner regions 11f, 12f shown in FIG. 9). This also improves the reliability of the electrical connection. Furthermore, by providing the hardened region A in the first branch piece 11 and the second branch piece 12 as described above, it is possible to prevent the insertion load from falling below the lower limit specification value.

[0053] In addition, in this embodiment, the hardened region A is provided on at least one of the end surfaces of the first branch piece 11 and the second branch piece 12 in the width direction D4 (Y direction) perpendicular to the press-fit direction D2 and the deformation direction D1.

[0054] This makes it easier to process the hardened region A by providing the hardened region A on a flat surface compared to an embodiment in which the hardened region A is provided on curved surfaces that are both end faces in the deformation direction D1 of the first branch piece 11 and the second branch piece 12. Furthermore, by providing the hardened region A on both end faces in the width direction D4 (Y direction) of the first branch piece 11 and the second branch piece 12, it is possible to prevent variations in the elastic deformation of the first branch piece 11 and the second branch piece 12 in the width direction D4 (Y direction) more effectively than when the hardened region A is provided only on one end face.

[0055] In this embodiment, the hardened region A is located closer to the root portions 11b and 12b than the position of the through-hole 111 after press-fitting in the press-fitting direction D2.

[0056] This makes it possible to prevent the plating layer of the through-hole 111 and the first plating layer P1 of the press-fit terminal 1 from being significantly scraped off due to contact between the hardened region A or its vicinity and the through-hole 111.

[0057] In this embodiment, the hardened region A is formed by plastic working.

[0058] This allows the hardened region A to be formed by simpler processing than in embodiments where the hardened region A is formed by applying heat treatment, performing laser processing, or adding a reinforcing material.

[0059] In addition, in this embodiment, the first branch piece 11 and the second branch piece 12 have a first plating layer P1 provided on the surface and a second plating layer P2 located on the first plating layer P1 in a portion of the surface including the hardened region A.

[0060] Therefore, the second plating layer P2 can further increase the hardness of the hardened region A. Furthermore, when the hardened region A is formed, it is possible to prevent the first plating layer P1 from being partially peeled off, thereby exposing the surfaces of the first branch piece 11 and the second branch piece 12.

[0061] In this embodiment, the second plating layer P2 is made of a material that is more rigid than the first plating layer P1.

[0062] This allows the hardened area A to be further hardened by the second plating layer P2.

[0063] The inventions described in the specification and drawings of this application are as follows:

[0064] <Appendix 1> The base part and a pair of branched portions that are bifurcated from a root portion on the base portion side while being spaced apart from each other, have tips that curve so as to approach each other, and are elastically deformed when press-fitted into the insertion hole in a press-fitting direction; The pair of branched portions have hardened regions located closer to the base portion than the maximum length portion in the deformation direction before press-fitting into the insertion hole. A press-fit terminal characterized by:

[0065] <Appendix 2> When press-fitted, the pair of branched portions have arc-shaped portions at both ends in the deformation direction in a cross section perpendicular to the press-fitting direction, the arc-shaped portions having a curvature center on the center side of the insertion hole. 2. The press-fit terminal according to claim 1,

[0066] <Appendix 3> The hardened region is provided on at least one of both end surfaces of the pair of branch portions in a width direction perpendicular to the press-fitting direction and the deformation direction. 3. The press-fit terminal according to claim 1 or 2.

[0067] <Appendix 4> The hardened region is located closer to the base portion than the position of the insertion hole after press-fitting in the press-fitting direction. 4. The press-fit terminal according to any one of claims 1 to 3.

[0068] <Appendix 5> The hardened region is formed by plastic working. 5. The press-fit terminal according to any one of claims 1 to 4.

[0069] <Appendix 6> The pair of branched portions has a first plating layer provided on the surface and a second plating layer located on the first plating layer in a part of the surface including the hardened region. 6. The press-fit terminal according to any one of claims 1 to 5.

[0070] <Appendix 7> The second plating layer is made of a material having higher rigidity than the first plating layer. 7. The press-fit terminal according to claim 6,

[0071] <Appendix 8> A press-fit terminal according to any one of appendices 1 to 7; a laminated substrate on which a semiconductor element electrically connected to the press-fit terminal is mounted; A semiconductor device comprising:

[0072] <Appendix 9> The base part and a pair of branched portions that are bifurcated from a root portion on the base portion side while being spaced apart from each other, and whose tips are curved so as to approach each other and are elastically deformable; The pair of branched portions have hardened regions located closer to the base portion than the maximum length portion where the distance between them is greatest. A press-fit terminal characterized by:

[0073] <Appendix 10> The elastic deformation occurs when the press-fit terminal is press-fitted into the insertion hole in the press-fit direction, The press-fitting causes the pair of branched portions to deform in a deformation direction perpendicular to the press-fitting direction, thereby reducing the distance between them. 10. The press-fit terminal according to claim 9,

[0074] <Appendix 11> A press-fit terminal according to any one of appendix 9 and 10; a laminated substrate on which a semiconductor element electrically connected to the press-fit terminal is mounted; A semiconductor device comprising: [Industrial Applicability]

[0075] As described above, the present invention has the effect of satisfying the performance required for a press-fit terminal, and is useful for semiconductor devices such as power semiconductor devices. [Explanation of symbols]

[0076] 1 Press-fit terminal 10 Elastically deformable part 11 First branch piece 11a tip 11b Base part 11c Arc-shaped part 11d Round surface part 11f corner area 12 Second branch piece 12a tip 12b Base part 12c Arc-shaped part 12d round surface part 12f corner area 20 Base part 100 Semiconductor device 110 Substrate 111 through hole 120 Semiconductor elements 130 cases 140 Laminated Board 141 First conductor plate 142 Second conductor plate 143 Third conductor plate 144 Insulating plate 150 metal base 161~163 Wiring A hardening area Aa recess D1 Deformation direction D2 Press-fit direction D3 Board insertion direction D4 width direction J Bonding material L Maximum length M Encapsulating Material P1 First plating layer P2 Second plating layer S1 Most of the stress S2 mid-stress section S3 Small stress part T Tool Ta convex part

Claims

1. The base part and a pair of branched portions that are bifurcated from a root portion on the base portion side while being spaced apart from each other, have tips that curve toward each other, and are elastically deformed when press-fitted into the insertion hole in a press-fitting direction; The pair of branched portions have hardened regions located closer to the base portion than the maximum length portion in the deformation direction before press-fitting into the insertion hole. A press-fit terminal characterized by:

2. When press-fitted, the pair of branched portions have arc-shaped portions at both ends in the deformation direction in a cross section perpendicular to the press-fitting direction, the arc-shaped portions having a curvature center on the center side of the insertion hole.

2. The press-fit terminal according to claim 1.

3. The hardened region is provided on at least one of both end surfaces of the pair of branch portions in a width direction perpendicular to the press-fitting direction and the deformation direction.

2. The press-fit terminal according to claim 1.

4. The hardened region is located closer to the base portion than the position of the insertion hole after press-fitting in the press-fitting direction.

2. The press-fit terminal according to claim 1.

5. The hardened region is formed by plastic working.

2. The press-fit terminal according to claim 1.

6. The pair of branched portions has a first plating layer provided on the surface and a second plating layer located on the first plating layer in a part of the surface including the hardened region.

2. The press-fit terminal according to claim 1.

7. The second plating layer is made of a material having higher rigidity than the first plating layer.

7. The press-fit terminal according to claim 6.

8. The press-fit terminal according to any one of claims 1 to 7; a laminated substrate on which a semiconductor element electrically connected to the press-fit terminal is mounted; A semiconductor device comprising:

9. The base part and a pair of branched portions that are bifurcated from a root portion on the base portion side while being spaced apart from each other, and whose tips are curved so as to approach each other and are elastically deformable; The pair of branched portions have hardened regions located closer to the base portion than the maximum length portion where the distance between the branched portions is greatest. A press-fit terminal characterized by:

10. The elastic deformation occurs when the press-fit terminal is press-fitted into the insertion hole in the press-fit direction, The press-fitting causes the pair of branched portions to deform in a deformation direction perpendicular to the press-fitting direction, thereby reducing the distance between them.

10. The press-fit terminal according to claim 9.

11. The press-fit terminal according to claim 9 or 10; a laminated substrate on which a semiconductor element electrically connected to the press-fit terminal is mounted; A semiconductor device comprising:

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