Substrate connection structure and substrate connection method

Abstract

The present invention is a substrate connection structure (1) that comprises: a press-fit terminal (20) that has a terminal body part (21) that extends in a first direction and a needle eye–type press-fit part (22) that is provided partway along the terminal body part (21) and can elastically deform in a second direction that intersects the first direction; a substrate (10) that has a through hole (12) that passes in the first direction; and a conductive bonding part (30) that bonds the press-fit terminal (20) to the substrate (10). Residue (32) of a bonding part composition that is included in the bonding part (30) is present at the perimeter of the opening of the through hole (12) so as to be aligned with the press-fit terminal (20) in the second direction.

Description

Substrate connection structure and substrate connection method

[0001] The present disclosure relates to a substrate connection structure and a substrate connection method.

[0002] Conventionally, there has been known a press-fit terminal that is press-fitted into a through hole formed in a substrate and electrically connected to a conductive portion formed on an inner wall of the through hole. For example, the press-fit terminal described in Japanese Patent Application Laid-Open No. 2005-26052 (Patent Document 1 below) is conductively connected to an inner wall of a terminal hole of a printed circuit board by press-fitting a press-fit portion into the terminal hole.

[0003] Japanese Patent Application Laid-Open No. 2005-26052

[0004] Since the press-fit portion needs to connect the press-fit terminal to a printed circuit board with high contact pressure, it is necessary to use an expensive metal material having high yield strength. For this reason, when a press-fit terminal is used for connection to a printed circuit board, the cost inevitably increases, and there has been a demand for cost reduction of a substrate connection structure including a press-fit terminal.

[0005] The present disclosure provides a substrate connection structure including: a press-fit terminal having a terminal main body portion extending in a first direction, and a needle-eye-type press-fit portion provided midway in the terminal main body portion and elastically deformable in a second direction intersecting the first direction; a substrate having a through hole penetrating in the first direction; and a conductive joining portion that joins the press-fit terminal to the substrate, wherein a residue of a joining composition included in the joining portion is arranged around an opening of the through hole, aligned in the second direction with respect to the press-fit terminal.

[0006] The present disclosure also relates to a substrate connection method for electrically connecting a press-fit terminal, which has a terminal body portion extending in a first direction and a needle-eye type press-fit portion provided in the middle of the terminal body portion and elastically deformable in a second direction intersecting the first direction, to a substrate having a through-hole penetrating in the first direction, comprising: a preparation step of preparing the substrate in which the press-fit terminal is inserted into the through-hole in a state in which it can stand upright relative to the substrate by the press-fit portion, and a conductive bonding material is placed around a part of the opening of the through-hole; and a bonding material filling step of passing the substrate obtained in the preparation step through a reflow oven to melt the bonding material and fill it into the through-hole, wherein in the preparation step, the press-fit terminal and the bonding material are arranged to be aligned in the second direction.

[0007] According to this disclosure, it is possible to provide a substrate connection structure and substrate connection method that can reduce manufacturing costs and have high connection reliability.

[0008] Figure 1 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate according to one embodiment (before insertion). Figure 2 is a perspective view illustrating a method of connecting a press-fit terminal to a substrate (after insertion). Figure 3 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate (after insertion). Figure 4 is a cross-sectional view (section II of Figure 3) illustrating a method of connecting a press-fit terminal to a substrate (after insertion). Figure 5 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate (during reflow). Figure 6 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate (during reflow). Figure 7 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate (substrate connection structure) (after bonding). Figure 8 is a transverse cross-sectional view illustrating a comparative example of a press-fit terminal connection method (after insertion). Figure 9 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate (during reflow). Figure 10 is a longitudinal cross-sectional view illustrating a method of connecting a press-fit terminal to a substrate (substrate connection structure) (after bonding).

[0009] [Description of Embodiments of the Disclosure] First, embodiments of the disclosure will be listed and described.

[0010] [1] The present disclosure provides a substrate connection structure comprising: a press-fit terminal having a terminal body portion extending in a first direction and a needle-eye type press-fit portion provided in the middle of the terminal body portion and elastically deformable in a second direction intersecting the first direction; a substrate having a through-hole penetrating in the first direction; and a conductive bonding portion for bonding the press-fit terminal to the substrate, wherein the residue of the bonding portion composition contained in the bonding portion is arranged around the opening of the through-hole, aligned in the second direction relative to the press-fit terminal.

[0011] According to the above configuration, the press-fit terminal (press-fit portion) and the circuit board (through-hole) are electrically connected via the joint. Therefore, the press-fit terminal does not need to have high strength to guarantee electrical connection, and thus expensive metal materials do not need to be used.

[0012] Furthermore, with the above configuration, the press-fit portion only needs to have enough contact pressure to allow the press-fit terminal to stand upright in the through-hole, and high contact pressure to hold the press-fit terminal in the through-hole is unnecessary. Therefore, as with the above, it does not need to have high strength, and expensive metal materials do not need to be used. Consequently, the cost of the board connection structure equipped with press-fit terminals can be reduced.

[0013] Furthermore, when the conductive connection between the press-fit terminal and the substrate is made using a bonding material, there is a risk that voids may form in the bonding material filled in the through-hole, reducing the reliability of the connection. According to the substrate connection structure of this disclosure, it can be seen that the residue of the bonding composition causes the direction in which the bonding material flows into the through-hole during reflow to be a second direction relative to the press-fit terminal. With such a configuration, it is possible to suppress the formation of voids compared to when the bonding material flows into the press-fit terminal from a direction other than the second direction, thereby improving the reliability of the connection.

[0014] [2] [1] Preferably, the entire surface of the press-fit portion of the press-fit terminal is plated.

[0015] With the above configuration, the bonding material flows more easily into the inside of the press-fit section, thus further improving connection reliability.

[0016] [3] The present disclosure also relates to a substrate connection method for electrically connecting a press-fit terminal, which has a terminal body portion extending in a first direction and a needle-eye type press-fit portion provided in the middle of the terminal body portion and elastically deformable in a second direction intersecting the first direction, to a substrate having a through-hole penetrating in a first direction, comprising: a preparation step of preparing the substrate in which the press-fit terminal is inserted into the through-hole in a state in which it can stand upright relative to the substrate by the press-fit portion, and a conductive bonding material is placed around a part of the opening of the through-hole; and a bonding material filling step of passing the substrate obtained in the preparation step through a reflow oven to melt the bonding material and fill it into the through-hole, wherein in the preparation step, the press-fit terminal and the bonding material are arranged side by side in the second direction.

[0017] [Details of Embodiments of the Disclosure] An embodiment of the Disclosure is described below with reference to Figures 1 to 7. The Disclosure is not limited to these examples, and all modifications are intended to be included in the meaning and scope of the claims, as indicated by the claims. In each drawing, some parts of the configuration may be exaggerated or simplified for illustrative purposes. In the following description, the direction indicated by arrow Z is considered upward, the direction indicated by arrow X is considered left, and the direction towards the viewer is considered the front side.

[0018] As shown in Figure 7, the substrate connection structure 1 of this embodiment comprises a substrate 10 with its surface oriented vertically, a press-fit terminal 20 held by the substrate 10, and a joint portion 30 for joining the press-fit terminal 20 to the substrate 10. The vertical direction (Z direction) corresponds to the first direction of this disclosure, and the horizontal direction (X direction) corresponds to the second direction of this disclosure.

[0019] (Substrate 10) The substrate 10 comprises an insulating substrate 11 made of an insulating material such as synthetic resin, and conductive paths (not shown) formed in the insulating substrate 11. As shown in Figure 1, the insulating substrate 11 has through-holes 12 that extend vertically (Z direction) through the surface of the board. Lands 13 are formed at both the upper and lower ends of the through-holes 12. The inner walls 14 of the through-holes 12 electrically connect a pair of lands 13. The lands 13 and the inner walls 14 of the through-holes 12 are made of a conductive metal such as pure copper or a copper alloy. Although not shown, electronic components are mounted on the substrate 10, and the electronic components are connected to the conductive paths or through-holes 12 by soldering.

[0020] (Press-fit terminal 20) As shown in Figure 1, the press-fit terminal 20 has a terminal body portion 21 that extends in the vertical direction, and a press-fit portion 22 provided in the middle of the terminal body portion 21 and elastically deformable in the left-right direction in Figure 1. The press-fit portion 22 is a so-called needle-eye type. Specifically, the press-fit portion 22 is composed of a pair of elastic contact pieces 23 that extend along the plate surface (X-Z plane) of the flat tab-shaped (flat) terminal body portion 21 and protrude in the direction intersecting the longitudinal direction (X direction) and extend in the vertical direction (Z direction), and an eye hole 24 that extends elongated vertically between the pair of elastic contact pieces 23 and opens in the front-back direction (Y direction intersecting the plate surface of the terminal body portion 21).

[0021] The press-fit terminal 20 has a plating layer (not shown) formed on its entire surface by a plating process. In other words, the press-fit terminal 20 is plated after it has been formed into a piece with the press-fit portion 22 by a pressing process (hereinafter sometimes referred to as "post-plating"). By applying this plating process, the wettability of the press-fit terminal 20 to the solder 30, which will be described later, is improved.

[0022] The material of the press-fit terminal 20 is, for example, brass or pure copper. If the power supply device in which the press-fit terminal 20 is used is for communication or low-current applications, brass is preferred as the material of the press-fit terminal 20, and if the power supply device is for high-current applications, pure copper is preferred as the material of the press-fit terminal 20. For example, low-cost brass may be used in areas with small terminal sizes, and highly conductive pure copper may be used for high-current lines with large terminal sizes. However, the material of the press-fit terminal 20 is not limited to brass or pure copper.

[0023] (Joint 30) The joint 30 in this embodiment (see Figure 7) is, for example, solder. Soldering is performed by printing or applying solder paste (an example of a bonding material) to the area around the opening of the through-hole 12, and then passing the substrate 10, with the press-fit terminal 20 inserted into the through-hole 12, through a reflow oven (also called through-hole reflow). Alternatively, manual soldering may be performed as a method other than through-hole reflow. For example, lead-free solder can be used as the solder. Hereafter, it may also be referred to as "solder 30". Also, the solder paste (bonding material) may be referred to as "solder paste 30". Examples of joints 30 other than solder include brazing materials used for soldering.

[0024] (Method and structure 1 for connecting press-fit terminal 20 to a circuit board) Next, the method and structure 1 for connecting press-fit terminal 20 to a circuit board will be described. In the press-fit terminal 20 of this embodiment described above, the left-right dimension (hereinafter referred to as "maximum diameter") BL of the press-fit portion 22 is approximately the same as or slightly larger than the diameter AL of the through-hole 12. In the case of Figure 1, the maximum diameter BL of the press-fit portion 22 is approximately 1.1 times the diameter AL of the through-hole 12.

[0025] As described above, the press-fit portion 22 (elastic contact piece 23) is elastically deformable in the X direction, and the press-fit terminal 20 of this embodiment is press-fitted into the through-hole 12 from the upper surface 10A side of the substrate 10, and is able to stand upright within the through-hole 12. In detail, when the press-fit terminal 20 is inserted into the through-hole 12, the press-fit portion 22 elastically deforms while slightly shrinking in diameter, generating a small elastic force against the inner wall 14 of the through-hole 12. This small elastic force allows the press-fit terminal 20 to stand upright within the through-hole 12.

[0026] In this embodiment, the role of the press-fit portion 22 of the press-fit terminal 20 is not to hold or connect the press-fit terminal 20 in the through-hole 12, but rather to provide support (temporary fastening). Therefore, compared to conventional press-fit terminals, the material strength (yield strength) can be relatively lower, and the wall thickness can be reduced. In addition, the length of the eye hole 24 can be increased.

[0027] (Preparation Step) First, solder paste (an example of a bonding material) 30 is printed on the upper surface 10A of the substrate 10 near the opening of the through-hole 12, and the press-fit terminal 20 is inserted into the through-hole 12 from the upper surface 10A side of the substrate 10 (see Figures 1 to 3). As described above, the press-fit terminal 20 is made to stand upright inside the through-hole 12 by slightly reducing the diameter of the press-fit portion 22. The solder paste 30 may also be applied after inserting the press-fit terminal 20 into the through-hole 12.

[0028] (Bonding material filling process) Next, solder 30 is filled into the through-hole 12. Specifically, the substrate 10 with the press-fit terminal 20 standing upright inside the through-hole 12 is passed through a reflow oven. The solder paste 30 melts during reflow and fills the inside of the through-hole 12, forming a fillet 31 on the land 13 (see Figure 7). As a result, the press-fit portion 22 is held in place by the solder 30 in the through-hole 12 and electrically connected to the inner wall 14 and the land 13. After reflow, flux residue (an example of residue of the bonding composition) 32, which is a composition contained in the solder paste 30, remains in the area on the upper surface 10A of the substrate 10 where the solder paste 30 was printed.

[0029] However, during this reflow process, there is a risk that the solder 30 may not be sufficiently filled into the through-hole 12, causing voids to form within the solder 30. The solder 30 flowing into the through-hole 12 from the upper surface 10A of the substrate 10 tends to fill preferentially through capillary action in the narrow path near the contact point between the elastic contact piece 23 and the inner wall 14 of the through-hole 12. As a result, before the entire through-hole 12 is filled with solder 30, solder 30 may accumulate in the upper and lower openings of the through-hole 12, blocking the openings. In such cases, residual air in the central part of the through-hole 12 (such as inside the eyehole 24) and volatile components generated from flux seeping from the solder 30 can form voids, which may reduce connection reliability.

[0030] In this embodiment, to address these problems, the relationship between the orientation of the solder paste 30 printed or applied to the upper surface 10A of the substrate 10 and the press-fit terminal 20 is defined in the preparation step described above, thereby suppressing the occurrence of voids in the joint 30. Specifically, in the preparation step described above, as shown in Figures 2 to 4, the printed (applied) area of ​​the solder paste 30 is made to coincide with the protrusion direction (X direction) of the press-fit portion 22 (elastic contact piece 23) relative to the press-fit terminal 20. The solder paste 30 is printed (applied) only to a part and one location around the opening of the through-hole 12, and is not applied to the part facing the through-hole 12.

[0031] Figure 4 is a cross-sectional view (section II in Figure 3) of the area near the opening of the through-hole 12. Hereinafter, when viewed from the Z direction, the contact area between the press-fit portion 22 and the two inner walls 14 located closer to the printed solder paste 30 will be referred to as contact area A, and the contact area between the press-fit portion 22 and the two inner walls 14 located further away from the printed solder paste 30 will be referred to as contact area B, and will be described in detail.

[0032] As described above, when the substrate 10 with the press-fit terminals 20 standing upright is passed through a reflow oven, a portion of the solder paste 30 (hereinafter referred to as solder 30), which has been melted by the heat, first flows preferentially downward from the upper surface 10A of the substrate 10 by capillary action through the narrow space between the contact portion A and the inner wall 14 that extends in the Z direction near the contact portion A. At the same time, a portion of the solder 30 flows towards the contact portion B side through the opening on the upper end side of the through-hole 12, and flows downward from the upper surface 10A of the substrate 10 by capillary action through the narrow space between the contact portion B and the inner wall 14 that extends in the Z direction near the contact portion B. At this time, since the contact portion B is located further from the solder paste 30 than the contact portion A, there is a time difference T1 between the timing of the solder 30 flowing into the through-hole 12 from the contact portion A side and the timing of the solder 30 flowing into the through-hole 12 from the contact portion B side. In other words, time T1 is the time it takes for the solder 30 to move from contact point A to contact point B.

[0033] During this time T1, the solder 30 that has flowed into the through-hole 12 on the contact portion A side reaches the opening at the lower end of the through-hole 12, blocking the opening. Then, near the contact portion B, it travels through the narrow space between the contact portion B and the inner wall 14, filling the eyehole 24 upwards by capillary action (see Figure 5). As the solder 30 rises, it pushes out any remaining air in the center of the through-hole 12 (such as the inside of the eyehole 24) and volatile components of flux that have seeped out from the solder 30 towards the opening at the upper end of the through-hole 12.

[0034] Meanwhile, on the upper surface 10A side of the substrate 10, the solder 30 that has advanced toward the contact portion B at the opening at the upper end of the through-hole 12 reaches the vicinity of the contact portion B and fills the upper part of the through-hole 12 together with the solder 30 that has risen from below (see Figure 6). At this time, any air or volatile components of the flux that remained inside the through-hole 12 are pushed out by the solder 30 advancing from both sides and released to the outside of the through-hole 12 (towards the upper left in Figure 6). Finally, a fillet 31 is formed on the land 13 (see Figure 7).

[0035] Thus, the substrate connection method of this embodiment can suppress the generation of voids in the solder 30. Furthermore, the press-fit portion 22 is held in the through-hole 12 by the solder 30 and is electrically connected to the inner wall 14 and land 13 of the through-hole 12.

[0036] Next, a comparative example is shown. Figures 8 to 10 show an example in which the solder paste 30 is arranged in a direction (Y direction) intersecting the protrusion direction (X direction) of the press-fit portion 22. Hereinafter, when viewed from the Z direction (see Figure 8), the two contact portions of the press-fit portion 22 that are located close to the printed solder paste 30 will be referred to as contact portions C, and the contact portion located farther from the printed solder paste 30 will be referred to as contact portions D.

[0037] When the comparative example substrate 10 is passed through a reflow oven, a portion of the solder paste 30 (hereinafter referred to as solder 30), which has been melted by the heat, first travels along the opening at the upper end of the through-hole 12 to the vicinity of contact portion C. Near contact portion C, it travels through the narrow space between the contact portion C and the inner wall 14, which extends in the Z direction, and flows downward from the upper surface 10A of the substrate 10 by capillary action. Furthermore, a portion of the solder 30 travels along the opening at the upper end of the through-hole 12 toward contact portion D, and near contact portion D, it travels through the narrow space between the contact portion D and the inner wall 14, which extends in the Z direction, and flows downward from the upper surface 10A of the substrate 10 by capillary action. At this time, since the distance between contact portion C and contact portion D is shorter than the distance between contact portion A and contact portion B as described above, the timing of the solder 30 flowing into the through-hole 12 from the vicinity of contact portion C and the timing of the solder 30 flowing into the through-hole 12 from the vicinity of contact portion D are delayed by a time T2 which is shorter than the time T1 described above. In other words, the timing at which the solder 30 flows into the through-hole 12 from the vicinity of contact point C is only slightly different from the timing at which the solder 30 flows into the through-hole 12 from the vicinity of contact point D.

[0038] As a result, the solder 30 that flows in from near contact point C and blocks the opening at the lower end of the through-hole 12, and then rises through the narrow space near contact point D, and the solder 30 that flows into the through-hole 12 from near contact point D collide inside the through-hole 12, making it easy for air and volatile components of flux to remain between these solder 30. In other words, with this configuration, voids are more likely to occur inside the through-hole 12 compared to the above embodiment.

[0039] As described above, the press-fit terminal 20 of this disclosure does not require a high contact pressure for the press-fit portion 22 and does not require the use of expensive metal materials with high yield strength, thus reducing material costs. In short, conventional press-fit terminals require ensuring the self-supporting, holding, and electrical connection reliability of the terminal, which results in high overall costs. However, with the press-fit terminal 20 of this embodiment, it is only necessary to ensure the self-supporting of the terminal, and the holding and electrical connection reliability of the terminal can be ensured by solder 30 (soldering), thus keeping overall costs low.

[0040] Furthermore, according to this disclosure, since voids are less likely to occur in the solder 30 that holds the substrate 10 and the press-fit terminal 20 in place and provides an electrical connection, connection reliability can be improved.

[0041] (Effects of the Embodiment) The substrate connection structure 1 of this embodiment comprises a press-fit terminal 20 having a terminal body portion 21 extending in the Z direction and a needle-eye type press-fit portion 22 provided in the middle of the terminal body portion 21 and elastically deformable in the X direction intersecting the Z direction, a substrate 10 having a through-hole 12 penetrating in the Z direction, and conductive solder 30 for joining the press-fit terminal 20 to the substrate 10, wherein flux residue (flux traces 32) contained in the solder 30 is arranged around the opening of the through-hole 12, aligned in the X direction relative to the press-fit terminal 20.

[0042] According to the above configuration, the press-fit terminal 20 (press-fit portion 22) and the substrate 10 (through-hole 12) are electrically connected via the joint portion 30. Therefore, the press-fit terminal 20 does not need to have high strength to guarantee electrical connection, and thus expensive metal materials do not need to be used.

[0043] Furthermore, according to the above configuration, the press-fit portion 22 only needs to have a contact pressure sufficient to allow the press-fit terminal 20 to stand on its own in the through hole 12, and a high contact pressure for holding the press-fit terminal 20 in the through hole 12 is not required. Therefore, similar to the above, it is not necessary for the press-fit portion to have high yield strength, and it is not necessary to use an expensive metal material. Accordingly, the cost of the board connecting structure 1 including the press-fit terminals 20 can be reduced.

[0044] Furthermore, when the conductive connection between the press-fit terminal 20 and the substrate 10 is made by solder 30 as described above, there is a possibility that voids are generated in the solder 30 filled in the through hole 12, thereby reducing connection reliability. According to the substrate connection method of the present embodiment, the direction in which the solder 30 flows into the through hole 12 during reflow is set to the X direction with respect to the press-fit terminal 20, whereby generation of voids can be suppressed compared to a case where the solder flows in from other directions, and connection reliability can be improved.

[0045] Further, the entire surface of the press-fit portion 22 of the press-fit terminal 20 is plated. According to such a configuration, the solder 30 can easily flow into the inner side (eye hole 24) of the press-fit portion 22, so that connection reliability can be further improved.

[0046] Further, the present embodiment is a substrate connection method for conductively connecting a press-fit terminal 20 to a substrate 10 having a through hole 12 penetrating in the Z direction, wherein the press-fit terminal 20 includes: a terminal body portion 21 extending in the Z direction; and a needle eye-type press-fit portion 22 provided midway in the terminal body portion 21 and elastically deformable in an X direction intersecting the Z direction, the method comprising: a preparation step of preparing the substrate 10 in a state where the press-fit terminal 20 is inserted into the through hole 12 in a state where the press-fit portion 22 can allow the press-fit terminal 20 to stand on its own with respect to the substrate 10, and a conductive solder paste (solder 30) is arranged on a part of the periphery of an opening of the through hole 12; and a bonding material filling step of passing the substrate 10 obtained in the preparation step through a reflow furnace to melt the solder 30 and fill the inside of the through hole 12 with the molten solder, wherein in the preparation step, the press-fit terminal 20 and the solder paste (solder 30) are arranged so as to be aligned in the X direction.

[0047] <Other Embodiments> The present disclosure is not limited to the embodiments described in the above description and drawings, for example, the following embodiments are also included in the technical scope.

[0048] (1) In the above embodiment, an embodiment in which a plating layer is formed on the entire surface of the press-fit terminal 20 by post-plating is shown, but the plating layer may be formed on a part of the press-fit terminal by pre-plating.

[0049] (2) In the above embodiment, an embodiment in which solder paste 30 is printed on the upper surface 10A of the substrate 10 and the press-fit terminal 20 is inserted into the through-hole 12 from the upper surface 10A side of the substrate 10 is shown, but the printing surface of the bonding material and the insertion direction of the press-fit terminal are not limited to the above embodiment. For example, the bonding material may be printed on the lower surface side of the substrate, and the press-fit terminal may be inserted from the lower surface side of the substrate. In short, it is only necessary that the press-fit terminal and the bonding material are arranged so as to be aligned in the second direction.

[0050] 1: Substrate connection structure 10: Substrate 10A: Upper surface 11: Insulating base material 12: Through-hole 13: Land 14: Inner wall 20: Press-fit terminal 21: Terminal body portion 22: Press-fit portion 23: Elastic contact piece 24: Eyelet 30: Solder, solder paste, bonding material, bonding portion 31: Fillet 32: Flux trace (residue of bonding portion composition) A: Contact portion AL: Diameter B: Contact portion BL: Maximum diameter C: Contact portion D: Contact portion T1: Time T2: Time

Claims

1. A substrate connection structure comprising: a press-fit terminal having a terminal body portion extending in a first direction and a needle-eye type press-fit portion provided in the middle of the terminal body portion and elastically deformable in a second direction intersecting the first direction; a substrate having a through-hole penetrating in the first direction; and a conductive bonding portion for bonding the press-fit terminal to the substrate, wherein the residue of the bonding portion composition contained in the bonding portion is arranged around the opening of the through-hole, aligned in the second direction relative to the press-fit terminal.

2. A substrate connection method for electrically connecting a press-fit terminal, which has a terminal body portion extending in a first direction and a needle-eye type press-fit portion provided in the middle of the terminal body portion and elastically deformable in a second direction intersecting the first direction, to a substrate having a through-hole penetrating in a first direction, comprising: a preparation step of preparing the substrate in which the press-fit terminal is inserted into the through-hole in a state in which it can stand upright relative to the substrate by the press-fit portion, and a conductive bonding material is placed around a part of the opening of the through-hole; and a bonding material filling step of passing the substrate obtained in the preparation step through a reflow oven to melt the bonding material and fill it into the through-hole, wherein in the preparation step, the press-fit terminal and the bonding material are arranged to be aligned in the second direction.

3. The substrate connection method according to claim 2, wherein the press-fit terminal has a plated finish applied to the entire surface of the press-fit portion.

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