Spacer for circuit board

Abstract

A circular conductor pattern (5) corresponding to the lower end surface (1b) of a cylindrical spacer (1) is formed on a circuit board (4), a solder resist layer (6) is formed around the conductor pattern (5), and the spacer (1) is mounted in a posture in which the lower end surface (1b) abuts against the conductor pattern (5). A circular solder resist layer (16) is formed at the center of the conductor pattern (5) and protrudes upward. The spacer (1) is positioned by forming a cylindrical fitting section (15b) on the lower end surface (1b) of the spacer (1) and fitting the circular solder resist layer (16). Furthermore, a reduced diameter portion (14b) is formed around the lower end surface (1b), the conductor pattern (5) is exposed upward, and when the spacer (1) is mounted, molten solder is attached to the outer peripheral surface of the reduced diameter portion (14b) by surface tension on the conductor pattern (5), thereby forming a weld leg (19).

Description

Technical Field

[0001] The present invention relates to a spacer for a circuit substrate. Background Art

[0002] For example, as described in Patent Document 1, such a spacer is used to fasten a fastening object such as another circuit board, a busbar, a round terminal, etc. at a distance on a circuit board. The spacer is pre-installed on the circuit board, and the fastening object is fastened to the internal thread formed on the spacer by screws, for example.

[0003] Hereinafter, a conventional spacer mounting structure with respect to a circuit board such as Patent Document 1 will be described. Figure 6 In the prior art 1 shown, an internal thread 102 is provided along the axis C of the spacer 101, and its lower end surface 101b is in a ring shape surrounding the opening of the internal thread 102. A conductor pattern 105 is formed in the area on the circuit substrate 104 corresponding to the lower end surface 101b of the spacer 101, and a solder resist layer 106 is formed around it. For example, in the installation operation of the spacer 101 using reflow soldering, solder paste 117 is printed on the conductor pattern 105, and the spacer 101 is placed at a desired position on the circuit substrate 104 using a mounter, and installed through a heating process using an oven.

[0004] However, in the mounting structure of the spacer 101 of the prior art 1, since the spacer 101 is bonded to the conductor pattern 105 only via the planar solder layer 118 corresponding to the lower end surface 101 b , there is a problem that the bonding strength with the circuit board 104 is low.

[0005] As a countermeasure, Figure 6 As in the prior art 2 shown in FIG. 1 , a mounting structure is also implemented in which the conductor pattern 105 is extended toward the outer peripheral side and exposed upward. In this case, the molten solder adheres to the outer peripheral surface of the spacer 101 by surface tension and solidifies during the heating process, thereby forming a solder fillet 119 having a substantially triangular cross-section on the outer periphery of the lower end of the spacer 101. As a result, the entire periphery of the lower end of the spacer 101 is constrained to the conductor pattern 105 via the solder fillet 119, so that the bonding strength with the circuit board 104 is greatly improved.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-122488 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in the mounting structure of the spacer 101 of the prior art 2, there is a problem that the area occupied by the spacer 101 on the circuit board 104 increases.

[0011] That is, in the case of the prior art 1, an area corresponding to the outer shape of the circular spacer 101 when viewed from above is occupied on the circuit substrate 104, while in the case of the prior art 2, the area of ​​the annular solder fillet 119 surrounding the spacer 101 is also added as the occupied area. Such an increase in the occupied area of ​​the spacer 101 may affect the arrangement of the surrounding electronic components, and may become a major factor restricting the substrate design.

[0012] The present invention has been made to solve such a problem, and an object of the present invention is to provide a spacer for a circuit board which can be mounted on a circuit board with high bonding strength while preventing an increase in the occupied area on the circuit board.

[0013] Solutions for solving problems

[0014] In order to achieve the above-mentioned purpose, the spacer of the circuit substrate of the present invention is characterized in that the spacer is a spacer of the circuit substrate applied to the mounting structure of the circuit substrate, wherein a conductor pattern with a shape corresponding to one end face of the columnar spacer is formed on the circuit substrate, and a solder resist layer is formed around the conductor pattern on the circuit substrate, and the spacer is formed so that the spacer can be mounted on the circuit substrate with one end face abutting against the conductor pattern, and on the other hand, a fastening object can be fastened to the other end face of the spacer, and a reduced portion with a reduced outer shape is formed around one end face of the spacer, so that when the spacer is mounted on the circuit substrate, a solder fillet formed by molten solder is formed between the conductor pattern exposed around and the outer peripheral surface.

[0015] According to the spacer of the circuit substrate constructed as above, when the spacer is mounted on the conductor pattern, the conductor pattern is exposed in a ring shape around the reduced diameter portion, and the molten solder on the conductor pattern adheres to the outer peripheral surface of the reduced diameter portion by surface tension and solidifies, thereby forming a solder fillet. As a result, not only the lower end surface of the spacer is joined to the conductor pattern via the planar solder layer, but also the entire surrounding of the reduced diameter portion is constrained on the conductor pattern via the solder fillet. Moreover, although the solder fillet is in a ring shape surrounding the spacer, it is received in the reduced diameter portion, and therefore does not become a major factor in increasing the occupied area of ​​the spacer.

[0016] As another embodiment, a cylindrical fitting portion may be formed on one end surface of the spacer, and the cylindrical fitting portion may fit with the outer periphery of a circular solder resist layer formed to protrude in a stepped manner at the center of the conductor pattern on the circuit board.

[0017] Therefore, when the spacer is mounted on the conductor pattern, the cylindrical fitting portion of the spacer is fitted into the circular solder resist layer on the circuit board, whereby the spacer is positioned at a desired position.

[0018] As another embodiment, a female thread for fastening a fastening object may be provided through the spacer from one end surface to the other end surface, and the cylindrical fitting portion may be formed at an opening of the female thread.

[0019] Therefore, the cylindrical fitting portion can be formed by only slightly changing the shape of the opening of the internal thread.

[0020] As another embodiment, the spacer may have a symmetrical shape in the axial direction by forming a reduced portion on the other end surface in addition to the one end surface.

[0021] Therefore, regardless of whether the spacer is mounted on the circuit board in a posture in which either one end surface or the other end surface abuts on the conductor pattern, the reduced portion can still perform a desired function.

[0022] As another embodiment, the spacer may have a cylindrical fitting portion formed on not only one end surface but also the other end surface, thereby forming a shape symmetrical in the axial direction.

[0023] Therefore, regardless of whether the spacer is mounted on the circuit board in a posture in which either one end surface or the other end surface abuts against the conductor pattern, the cylindrical fitting portion performs a desired function.

[0024] As another solution, the spacer may be made of aluminum.

[0025] Therefore, the spacer can be made lighter while compensating for the disadvantage in terms of bonding strength in the case where the spacer is made of aluminum.

[0026] As another embodiment, the spacer may be made of a conductive material.

[0027] Therefore, the conductor pattern on the circuit board and the fastening object can be electrically connected via the spacer.

[0028] Effects of the Invention

[0029] According to the spacer for a circuit board of the present invention, it is possible to mount the spacer on the circuit board with high bonding strength while preventing an increase in the occupied area on the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a perspective view showing a state where another circuit substrate is fastened to a circuit substrate using the spacer according to the embodiment.

[0031] Figure 2 is with Figure 1 Corresponding exploded perspective view.

[0032] Figure 3 This is a perspective view showing a state where a bus bar is fastened to a circuit board using the spacer according to the embodiment.

[0033] Figure 4 This is a perspective view showing a state where a round terminal is fastened to a circuit board using the spacer according to the embodiment.

[0034] Figure 5 It is a cross-sectional view showing a spacer.

[0035] Figure 6 is equivalent to Figure 5 A is an enlarged cross-sectional view of a detailed welding position of a spacer compared with prior art 1 and prior art 2. DETAILED DESCRIPTION

[0036] Hereinafter, one embodiment of a spacer for a circuit board embodying the present invention will be described.

[0037] Figure 1 1 is a perspective view showing a state where another circuit substrate is fastened to a circuit substrate using the spacer of this embodiment. Figure 2 is with Figure 1 The corresponding exploded perspective diagram, Figure 3 is a perspective view showing a state where a busbar is fastened to a circuit board using a spacer. Figure 4 is a perspective view showing how a circular terminal is fastened to a circuit board using a spacer. Figure 5 is a cross-sectional view showing a spacer. Figure 1 The posture of the spacer is used to indicate the up and down directions.

[0038] First, the schematic structure of the spacer is described. Figure 2 , Figure 5 As shown, the spacer 1 is cylindrical and extends in the vertical direction. An internal thread 2 is provided through the spacer 1 along the axis C. The upper end surface 1a of the spacer 1 (equivalent to the "other end surface" of the present invention) opens the upper portion of the internal thread 2 through a guide portion 3a that expands in a conical shape upward. Similarly, the lower end surface 1b of the spacer 1 (equivalent to the "one end surface" of the present invention) opens the lower portion of the internal thread 2 through a guide portion 3b that expands in a conical shape downward (equivalent to the "opening portion of the internal thread" of the present invention).

[0039] The spacer 1 of this embodiment is made of a conductive metal material such as aluminum, and its manufacturing method can be arbitrarily applied to known techniques such as cutting, punching, forming, cold forging, etc. When aluminum is used as the material, in order to prevent the reduction of the bonding strength of the solder due to the oxide film formed on the surface, a surface treatment such as tinning is performed.

[0040] However, the material of the spacer 1 does not necessarily need to be a metal material. For example, as described later, since the lower portion of the spacer 1 is mounted on the circuit board 4, the lower portion may be made of metal, and the other portions may be insert-molded with a synthetic resin material. Alternatively, the spacer 1 may be injection-molded as a whole with a synthetic resin material, and its surface may be plated with metal to impart conductivity and enable welding.

[0041] A conductor pattern 5 having a circular shape corresponding to the lower end surface 1b of the spacer 1 is formed on the upper surface of the circuit substrate 4 on which such a spacer 1 is mounted, and a solder resist layer 6 is formed around the conductor pattern 5. For example, the conductor pattern 5 is formed by etching the copper foil attached to the circuit substrate 4 in a manner that leaves an area of ​​the conductor pattern 5. In addition, the solder resist layer 6 is formed by screen-printing solder resist ink in a manner that leaves an area of ​​the conductor pattern 5 and curing it by ultraviolet irradiation. However, it is not limited to these methods, and other methods can also be applied.

[0042] The spacer 1 is mounted on the circuit board 4 together with the electronic components (not shown) by, for example, reflow soldering. The spacer 1 is printed with solder paste on the area of ​​the conductor pattern 5, and after the spacer 1 is mounted by a mounter, it is mounted through a heating process using an oven. However, the content of the mounting operation is not limited to this, and it can also be implemented by, for example, reflow soldering.

[0043] The spacer 1 mounted on the circuit board 4 serves to separate the Figure 1 , 2 Another circuit substrate 7 shown, Figure 3 The busbar 8 shown Figure 4 The circular terminals 9 and other fastening objects shown have a function of fastening to the circuit board 4 at predetermined intervals.

[0044] When another circuit substrate 7 is fixed above the circuit substrate 4, as shown in FIG. Figure 1 , 2 As shown, for example, spacers 1 are pre-installed at four corners (only one location is shown) on the circuit substrate 4. Figure 1 As shown, another circuit substrate 7 is arranged above the circuit substrate 4 and is abutted against the upper end surface 1a of the spacer 1, and screws 11 are screwed into the internal threads 2 of each spacer 1 through screw holes 7a and washers 10 that pass through the four corners of the other circuit substrate 7.

[0045] Thus, the other circuit substrate 7 is fastened to the circuit substrate 4 with a gap 12 corresponding to the length of the spacer 1, and the electronic components mounted on the circuit substrate 4 are prevented from interfering with the other circuit substrate 7 through the gap 12. In addition, since the spacer 1 is conductive, if necessary, the conductor pattern 5 on the circuit substrate 4 can be connected to the conductor pattern of the other circuit substrate 7 through the spacer 1.

[0046] In addition, if Figure 3 , 4 As shown, when the busbar 8 and the round terminal 9 extending from another circuit substrate 7 are connected to the circuit substrate 4, for example, in order to prevent interference with the electronic components on the circuit substrate 4, the busbar 8 and the round terminal 9 are sometimes separated and arranged above the circuit substrate 4. In this case, a spacer 1 having a length corresponding to the separation distance between the two is mounted on the circuit substrate 4, and the busbar 8 and the round terminal 9 are fastened to the upper end surface 1a thereof via a washer 10 and a screw 11. In this case, the conductor pattern 5 is electrically connected to any electronic component on the circuit substrate 4, and the electronic component is electrically connected to the other circuit substrate via the spacer 1, the busbar 8 or the round terminal 9.

[0047] It should be noted that the fastening structure of the other circuit board 7 or busbar 8 and round terminal 9 is not limited to the above. For example, a through hole may be formed on the spacer 1 instead of the internal thread 2, and the screw 11 may be screwed to a nut provided on the lower surface of the circuit board 4 through the through hole.

[0048] However, as described above, the spacer 1 is mounted on the circuit substrate 4, but Figure 6 In the prior art 1 described above, since the spacer 101 is bonded to the conductor pattern 105 only via the planar solder layer 118 formed on the lower end surface 101b, there is a problem of low bonding strength with the circuit substrate 4. In addition, in the prior art 2, although the solder fillet 119 is formed around the spacer 101 to improve the bonding strength, there is a problem that the area occupied by the spacer 101 on the circuit substrate 4 is increased by the amount of the area corresponding to the solder fillet 119 when viewed from above.

[0049] In order to eliminate such undesirable conditions, in the present invention, a reduced diameter portion (equivalent to the "reduced portion" of the present invention) having a reduced outer diameter (equivalent to the "external shape" of the present invention) is formed around the lower end surface 1b of the cylindrical spacer 1, thereby ensuring space for forming the solder fillet 19 to be described later without increasing the area occupied by the spacer 1 on the circuit substrate 4, the details of which are described below.

[0050] Figure 6 is equivalent to Figure 5Part A is an enlarged cross-sectional view showing in detail the welding position of the spacer 1 compared with the prior arts 1 and 2.

[0051] like Figure 2 , 5 As shown, the spacer 1 of this embodiment is symmetrical in the vertical direction (equivalent to the "symmetry in the axial direction" of the present invention). The purpose is to prevent the spacer 1 from being incorrectly mounted on the circuit substrate 4. During the installation operation of the spacer 1, no matter what posture it is placed on the circuit substrate 4, it can play the desired function, so that the installation operation can be easily performed.

[0052] The following is based on Figure 5 , 6 The reduced diameter portion 14b and the cylindrical fitting portion 15b formed on the lower end face 1b side are described. Since the reduced diameter portion 14a and the cylindrical fitting portion 15b on the upper end face 1a side are of the same shape and symmetrical in the vertical direction, repeated descriptions are omitted. The reduced diameter portion 14b whose outer diameter is reduced in a step-like manner is formed around the lower end face 1b of the spacer 1 as a whole. The vertical dimension L1 and the radial dimension L2 of the step of the reduced diameter portion 14b are respectively set to a size that does not hinder the formation of the solder fillet 19 by the molten solder, for example, both are set to 0.3 mm or more. However, it can also be set to less than 0.3 mm depending on the location and purpose of use, and the case where the reduced diameter portion 14b is set in this way is also included in the present invention.

[0053] Furthermore, at the lower end surface 1b of the spacer 1, the guide portion 3b expands downward, and the lower portion of the guide portion 3b is formed into a cylindrical shape having a constant inner diameter in the vertical direction. This portion corresponds to the cylindrical fitting portion 15b.

[0054] As described above, on the circuit substrate 4, a solder resist layer 6 is formed around the circular conductor pattern 5. Figure 6 As shown, in this embodiment, the outer diameter of the conductor pattern 5 is set to be substantially the same as the outer diameter of the spacer 1. In addition, a circular solder resist 16 centered on the axis C is also formed in the center of the conductor pattern 5, and as a result, the conductor pattern 5 is annular. Hereinafter, this portion is referred to as a circular solder resist 16, and the outer diameter of the circular solder resist 16 is set to be the same as or slightly smaller than the inner diameter of the cylindrical fitting portion 15b of the spacer 1.

[0055] Then, if Figure 6As shown, the thickness T2 of the solder resist layer 6 on the outer circumference and the circular solder resist layer 16 on the inner circumference is set larger than the thickness T1 of the conductor pattern 5 on the circuit substrate 4. In detail, the thickness T2 of the solder resist layer 6, 16 is set to be larger than the value obtained by adding the thickness T1 of the conductor pattern 5 to the thickness T3 of the solder paste 17. Even if the solder paste 17 melts, the thickness T3 will only change in a decreasing direction due to the evaporation of the flux and the formation of the solder fillet 19. Therefore, before the molten solder solidifies as the solder layer 18 and fixes the position of the spacer 1 on the conductor pattern 5, the relationship of T2>T1+T3 is maintained.

[0056] Therefore, the circular solder resist 16 protrudes upward in a stepped manner from the center of the surrounding conductor pattern 5 (specifically, the solder paste 17 on the conductor pattern 5). It should be noted that, since the thickness T2 of the circular solder resist 16 needs to be maintained in this size relationship, the solder resist 6 can be set to a thickness other than T2.

[0057] By setting the dimensions relative to each other as described above, during the installation operation of the spacer 1, when the spacer 1 is placed on the conductor pattern 5 printed with the solder paste 17, the cylindrical fitting portion 15b of the spacer 1 is embedded in the circular solder resist layer 16 protruding from the center of the conductor pattern 5. As a result, the spacer 1 is positioned at a desired position so that the circular solder resist layer 16 is aligned with the axis C, the outer peripheral surface thereof is aligned with the inner periphery of the solder resist layer 6, and the solder paste 17 is exposed in a ring shape around the reduced diameter portion 14b of the spacer 1.

[0058] Even if the solder paste 17 melts during the heating process using the furnace, the spacer 1 will continue to be positioned due to the engagement of the circular solder resist layer 16 with the cylindrical engagement portion 15b. Then, the molten solder exposed around the spacer 1 adheres to the outer peripheral surface of the reduced diameter portion 14b of the spacer 1 (equivalent to the "outer peripheral surface" of the present invention) by surface tension and solidifies, thereby forming a solder fillet 19 with a roughly triangular cross-section in the reduced diameter portion 14b. As a result, the spacer 1 not only has its lower end surface 1b bonded to the conductor pattern 5 via the planar solder layer 18, but also has a substantially triangular cross-section. Figure 6 Similarly to the prior art 2, the entire periphery of the reduced diameter portion 14b is bounded to the conductor pattern 5 via the solder fillet 19. Therefore, compared with the prior art 1, the spacer 1 can be mounted on the circuit board 4 with higher bonding strength.

[0059] In addition, although the welding leg 19 is in a ring shape surrounding the spacer 1, it does not exceed the outer diameter of the spacer 1 and is received in the reduced diameter portion 14b. Figure 6 As shown in the "equivalent occupied area" in the figure, the formation of the solder fillet 19 does not become a major factor in increasing the occupied area of ​​the spacer 1 on the circuit board 4. Therefore, the spacer 1 can be mounted on the circuit board 4 with an occupied area equal to that of the prior art 1. In other words, Figure 6Compared with the prior art 2, the occupied area on the circuit substrate 4 can be reduced.

[0060] The spacer 1 of this embodiment has a vertically symmetrical shape. Figure 6 Even when the device is mounted on the circuit board 4 in an upside-down posture, the same operational effects as described above can be achieved.

[0061] On the other hand, in this embodiment, the spacer 1 is positioned by fitting the circular solder resist layer 16 and the cylindrical fitting portion 15 b , thereby improving the accuracy of the mounting position of the spacer 1 . This point will be described based on a comparison with the prior arts 1 and 2.

[0062] First, in Figure 6 In the prior art 1 shown, the thickness of the solder resist layer 106 is set larger than the thickness of the conductor pattern 105 and the solder paste 117 on the circuit substrate 104. Therefore, the lower end of the spacer 101 placed on the conductor pattern 105 is embedded in the inner periphery of the solder resist layer 106, and a positioning effect to a desired position is obtained.

[0063] In contrast, in the prior art 2, in order to form the solder fillet 19, the conductor pattern is extended to the outer peripheral side and exposed upward, so the inner periphery of the solder resist layer 106 is separated from the outer periphery of the spacer 101 and the positioning effect cannot be obtained. Therefore, when the solder paste 17 melts, the spacer 101 floats on the molten solder and cannot maintain the desired position. It should be noted that although the surface tension of the molten solder generates the so-called self-centering phenomenon that guides the spacer 101 to the center portion on the conductor pattern 105, since its effect is small, accurate positioning cannot be expected.

[0064] As a countermeasure, in this embodiment, a circular solder resist layer 16 is formed on the inner circumference of the conductor pattern 5. Figure 6 As can be seen from the prior art 1 and 2, since the inner peripheral side of the conductor pattern 5 is an area relative to the unused dead space, the circular solder resist layer 16 can be formed without affecting the surrounding parts. Then, a cylindrical fitting portion 15b is formed on the spacer 1 side corresponding to the circular solder resist layer 16, and a positioning effect is obtained by embedding the circular solder resist layer 16 protruding from the center of the conductor pattern 5.

[0065] Therefore, similar to the prior art 1, the spacer 1 can be reliably installed at the desired position on the circuit substrate 4, thereby making a significant contribution to improving the position accuracy of the fastening object fastened to the spacer 1, such as another circuit substrate 7, busbar 8, circular terminal, etc.

[0066] In addition, in the present embodiment, the internal thread 2 is provided from the upper end face 1a to the lower end face 1b of the spacer 1, and the cylindrical fitting parts 15a and 15b are formed in the guide parts 3a and 3b as the opening parts thereof. For example, even if the internal thread 2 is not provided through and only stays on the upper end face 1a side, the positioning effect can be obtained by providing the cylindrical fitting part 15b in a recessed manner in the lower end face 1b of the spacer 1. Such a scheme is also included in the present invention, but in this case, it takes some effort to form the cylindrical fitting part 15b. When the internal thread 2 is passed through, the cylindrical fitting parts 15a and 15b can be formed by slightly changing the shape of the guide parts 3a and 3b as the opening parts thereof. Therefore, another advantage of further simplifying the production of the spacer 1 can be obtained.

[0067] On the other hand, the spacer 1 of the present embodiment is made of aluminum, and the spacer 101 of the prior art 1 and 2 is made of brass. The specific gravity of aluminum is about 2.7, and the specific gravity of brass is about 8.5. Although the two spacers 1 and 101 have slight differences in shape such as the presence or absence of the reduced diameter portion 14b and the cylindrical fitting portion 15b, since the volumes are substantially the same, it can be regarded as a weight ratio corresponding to each other's specific gravity. As a result, the spacer 1 of the present embodiment can be significantly lighter than the spacer 101 of the prior art 1 and 2.

[0068] Furthermore, as is well known, since the electrical conductivity and resistance of aluminum and brass are similar, the rated current value, temperature rise rate, etc. when the spacer 1 is used as a conductor can achieve comparable performance to the spacer 101 of the prior art 1 and 2 made of brass.

[0069] Then, although the aluminum spacer 1 has such advantages, it has a disadvantage that the bonding strength of the solder is reduced due to the oxide film. In view of this, in this embodiment, surface treatment such as tin plating is implemented, but from the perspective of manufacturing cost, etc., there is a case where surface treatment is not implemented.

[0070] In this case, there is a possibility that the bonding strength with the circuit board 4 is insufficient due to the oxide film, but in this embodiment, sufficient bonding strength can be maintained by forming the solder fillet 19. As a result, according to this embodiment, a new advantage of lightweight can be obtained while compensating for the disadvantages related to bonding strength when the spacer 1 is made of aluminum.

[0071] It should be noted that the above description is not intended to limit the present invention to the spacer 1 made of aluminum, and it is obvious that spacers made of brass and the like are also included in the present invention.

[0072] In addition, the formation of the solder fillet 19 also contributes to the following aspects. After the spacer 1 is mounted on the circuit board 4, the quality of the soldering is visually inspected. In the present embodiment, when the spacer 1 is normally soldered, a solder fillet 19 of a desired shape is formed around it, so the quality of the soldering can be judged based on the presence or absence and shape of the solder fillet 19. In this regard, the prior art 2 is also the same, but in the prior art 1 where the solder fillet 19 is not originally formed, it is difficult to judge the quality. Therefore, according to the present embodiment, the advantage of being able to easily implement the inspection of the spacer 1 after installation can also be obtained.

[0073] For example, in the above embodiment, the cylindrical fitting parts 15a and 15b are formed on the spacer 1 in addition to the reduced diameter parts 14a and 14b, but the cylindrical fitting parts 15a and 15b may be omitted.

[0074] In addition, in the above-mentioned embodiment, the spacer 1 is set to a cylindrical shape, and a vertically symmetrical shape is adopted to prevent mis-assembly, but it is not limited to this. For example, the spacer 1 may also be set to a quadrangular prism shape. In addition, the reduced diameter portion 14a and the cylindrical fitting portion 15a on the upper end surface 1a side may be omitted. In this case, although the function of preventing mis-assembly is lost, since the contact area with the busbar 8 and the round terminal 9 is increased, poor contact can be prevented more reliably.

[0075] Description of Reference Numerals

[0076] 1: Spacer;

[0077] 1a: upper end surface (the other end surface);

[0078] 1b: lower end surface (one end surface);

[0079] 2: Internal thread;

[0080] 3a, 3b: guide part (opening part);

[0081] 4: Circuit board;

[0082] 5: Conductor pattern;

[0083] 6: solder mask;

[0084] 7: Another circuit board (fastening object);

[0085] 8: Busbar (fastening object);

[0086] 9: Round terminal (fastening object);

[0087] 14a, 14b: reduced diameter portion (small diameter portion);

[0088] 15a, 15b: cylindrical fitting part;

[0089] 16: Circular solder mask;

[0090] 19: Solder foot.

Claims

1. A spacer for a circuit substrate, characterized in that: The spacer is a spacer of a circuit substrate applied to a mounting structure of a circuit substrate, wherein a conductor pattern having a shape corresponding to one end face of the columnar spacer is formed on the circuit substrate, and a solder resist layer is formed around the conductor pattern on the circuit substrate, and the spacer is formed so that the spacer can be mounted on the circuit substrate in a posture where the one end face abuts against the conductor pattern, and on the other hand, a fastening object can be fastened to the other end face of the spacer. A reduced portion having a reduced outer shape is formed around the one end surface of the spacer so that a fillet made of molten solder is formed between the conductor pattern exposed around and the outer peripheral surface when the spacer is mounted on the circuit board.

2. The spacer for a circuit substrate according to claim 1, wherein: A cylindrical fitting portion is formed on one end surface of the spacer, and the cylindrical fitting portion is fitted with the outer periphery of a circular solder resist layer formed to protrude in a stepped manner at the center of the conductor pattern on the circuit board.

3. The spacer for a circuit substrate according to claim 2, wherein: The spacer is provided with an internal thread for fastening the fastening object from the one end surface to the other end surface. The cylindrical fitting portion is formed at an opening of the internal thread.

4. The spacer for a circuit substrate according to claim 1, wherein: The spacer has the reduced portion formed on the other end surface in addition to the one end surface, thereby forming a shape symmetrical in the axial direction.

5. The spacer for a circuit substrate according to claim 2, wherein: The spacer has the cylindrical fitting portion formed on the other end surface in addition to the one end surface, thereby forming a symmetrical shape in the axial direction.

6. The spacer for a circuit board according to any one of claims 1 to 5, characterized in that: The spacer is made of aluminum.

7. The spacer for a circuit substrate according to any one of claims 1 to 5, characterized in that: The spacer is made of a conductive material.

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