Mounting structure of electrolytic capacitor

Abstract

To solve a problem of damaging a connection part of a terminal in the conventional mounting structure of a capacitor since the capacitor is easily oscillated.SOLUTION: A structure where an electrolytic capacitor 1 having a terminal 1B is mounted to a substrate 2 comprises: a soft pedestal base 3 and a hard pedestal base 4 provided between the electrolytic capacitor 1 and the substrate 2. The soft pedestal base 3 is formed of a material having a relatively soft quality and a thermal plasticity against the hard pedestal base 4. The terminal 1B is soldered to the substrate 2 so as to penetrate the soft pedestal base 3 and the hard pedestal base 4. The soft pedestal base 3 has a structure where it is welded to the substrate 2 so that one part thereof is penetrated by the hard pedestal base 4, and suppresses a stress generated in the terminal 1B of the electrolytic capacitor 1 in the case of enhancing a vibration resistance and receiving vibration inputs repeatedly.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mounting structure for an electrolytic capacitor, and more particularly to a mounting structure for an electrolytic capacitor having excellent vibration resistance. [Background technology]

[0002] Conventionally, an electrolytic capacitor mounting structure is disclosed, for example, in Patent Document 1. Patent Document 1 discloses a mounting structure in which an insulating plate having a through hole for inserting a terminal (lead wire) and an adhesive layer mainly made of thermosetting resin is attached to the end face of a chip-type capacitor, the terminal is bent at the bottom of the insulating plate, and the capacitor is mounted on a printed circuit board, and then heat treatment is performed to fix the bottom of the insulating plate to the printed circuit board. This capacitor mounting structure realizes surface mounting on a printed circuit board without changing the structure of the capacitor, and strengthens the connection state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-240706 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional capacitor mounting structure, when applied to, for example, electronic equipment in a vehicle, the capacitor is a component with a relatively large height, and therefore the capacitor is prone to vibration, and there is a problem in that the connection portion of the terminal may be damaged if the capacitor is subjected to repeated vibration input.

[0005] The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide a mounting structure for an electrolytic capacitor that can improve vibration resistance and suppress the stress generated in the terminals of the capacitor even when the capacitor is subjected to repeated vibration input. [Means for solving the problem]

[0006] The electrolytic capacitor mounting structure according to the present invention is a structure for mounting an electrolytic capacitor having terminals on a substrate, and includes a soft base disposed on the electrolytic capacitor side and a hard base disposed on the substrate side between the electrolytic capacitor and the substrate. The soft base is made of a material that is relatively soft compared to the hard base and has thermoplastic properties. The electrolytic capacitor mounting structure is characterized in that the terminals penetrate the soft base and the hard base and are soldered to the substrate, and a portion of the soft base penetrates the hard base and is welded to the substrate. Effect of the Invention

[0007] By adopting the above-mentioned configuration, the electrolytic capacitor mounting structure of the present invention can improve vibration resistance and suppress the stress generated in the terminals of the electrolytic capacitor even when subjected to repeated vibration input, making it highly useful for electronic devices installed in vehicles, for example. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a first embodiment of an electrolytic capacitor according to the present invention, including a cross-sectional view (upper left) showing the state of the soft base before reflow, a cross-sectional view based on line AA in the diagram (upper right), a cross-sectional view (lower left) showing the state of the soft base after reflow, and a bottom view of the hard base (lower right). [Diagram 2] 2A to 2C are perspective views illustrating a mounting method of the electrolytic capacitor shown in FIG. 1 in the order of steps. [Diagram 3] 4 is a time chart illustrating the reflow of the soft base and the solder. [Figure 4] 1A to 1C are cross-sectional views (upper left and right figures) showing a second embodiment of a mounting structure for an electrolytic capacitor according to the present invention, and bottom views (lower left and right figures) showing two other examples of a hard base. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment The mounting structure of the electrolytic capacitor shown in Fig. 1 includes a soft base 3 arranged on the electrolytic capacitor 1 side (upper side in the figure) and a hard base 4 arranged on the substrate 2 side between the electrolytic capacitor 1 and the substrate 2. The electrolytic capacitor 1 shown in the figure includes a pair of terminals 1B, 1B on one end surface (bottom surface) of a cylindrical body 1A. The substrate 2 is a so-called printed circuit board.

[0010] The soft base 3 is made of a material that is relatively soft compared to the hard base 4 and has thermoplastic properties, and although the material is not limited, it is typically a resin containing rubber. The soft base 3 in the illustrated example is cup-shaped to accommodate the lower side of the body 1A of the electrolytic capacitor 1, and has terminal through-holes 3A, 3A at the bottom through which the terminals 1B, 1B pass in the vertical direction.

[0011] The hard base 4 is made of a material that is relatively hard compared to the soft base 3, and although the material is not limited, an electrically insulating material can be used. The hard base 4 in the illustrated example is cup-shaped to accommodate the soft base 3 together with the electrolytic capacitor 1, and the bottom wall shown in the lower right diagram of Fig. 1 has terminal through-holes 4A, 4A continuing to the terminal through-holes 3A, 3A of the soft base 3, and base through-holes 4B, 4B that pass through a part of the soft base 4 in the vertical direction.

[0012] Here, the pair of terminals 1B, 1B of the electrolytic capacitor 1 are bent in opposite directions to each other, as shown in the upper right diagram of Fig. 1. Meanwhile, grooves 4C, 4C for accommodating the bent portions of both terminals 1B, 1B are formed in the bottom surface of the hard base 4. The bent portions of both terminals 1B, 1B are accommodated so that their lower surfaces are flush with the bottom surface of the hard base 4.

[0013] 1, the hard base 4 of this embodiment has two base through holes 4B, 4B arranged at positions that are line-symmetrical toward the outside with respect to a center line C that passes through the two terminal through holes 4A, 4A. Furthermore, the hard base 4 is configured such that the cross-sectional area of ​​the base through holes 4B, 4B is larger than the cross-sectional area of ​​the terminal through holes 4A, 4A.

[0014] 1, the mounting structure of the electrolytic capacitor is such that the terminals 1B, 1B penetrate through the terminal through-holes 3A, 3A of the soft base 3 and the terminal through-holes 4A, 4A of the hard base 4 and are soldered (S) to the board 2, and a part of the soft base 3 penetrates through the base through-holes 4B, 4B of the hard base 4 and is welded to the board 2. In other words, the mounting structure of the electrolytic capacitor is such that the base through-holes 4B, 4B are positioned closer to the outside than the two terminal through-holes 4A, 4A, and the soft base 4 is fixed to the board 2 outside the soldering (S), thereby alleviating stress on the solder S.

[0015] As a more preferred embodiment of the above-mentioned electrolytic capacitor mounting structure, the soft base 3 can be made of a material having a higher melting point than the melting point of the solder S that joins the terminal 1B and the substrate 2. As a more preferred embodiment of the above-mentioned electrolytic capacitor mounting structure, the soft base 3 can be made of a material having a specific gravity lower than that of the solder S. As a more preferred embodiment of the above-mentioned electrolytic capacitor mounting structure, the soft base 3 can be made of a material having elasticity.

[0016] Next, as a method for manufacturing the above-mentioned electrolytic capacitor mounting structure, a mounting method of the electrolytic capacitor according to the present invention will be described with reference to FIG. 2. In addition, (A) to (D) in FIG. 2 are an example of a production process for assembling a soft seat 3 and a hard seat 4 to an electrolytic capacitor 1, and (E) to (G) in the same figure are a mounting process for fixing the electrolytic capacitor 1 to a substrate 2. Therefore, the mounting structure of the electrolytic capacitor according to the present invention can basically be manufactured by the process of FIG. 2 (E) to (G). In other words, FIG. 2 illustrates a series of steps (A) to (G) including the production process, and the direction and posture of each component part during the process are not limited. In addition, although the soft seat 3 and the hard seat 4 shown in FIG. 2 are partially simplified in their configuration, their basic configuration is the same as that shown in FIG. 1.

[0017] The method for mounting an electrolytic capacitor includes a process (production process) in which, when mounting an electrolytic capacitor 1 on a substrate 2, a soft base 3 and a hard base 4 are set on the electrolytic capacitor 1 in that order, and terminals 1B, 1B are passed through the soft base 3 and the hard base 4.

[0018] That is, as shown in FIG. 2(A), the electrolytic capacitor 1 is set in a position with both terminals 1B, 1B facing upward, and as shown in FIG. 2(B), the soft base 3 is set so that the terminals 1B, 1B pass through the terminal through holes 3A, 3A, and then, as shown in FIG. 2(C), the hard base 4 is set so that the terminals 1B, 1B pass through the terminal through holes 4A, 4A.

[0019] Next, the above-mentioned method for mounting an electrolytic capacitor includes a step (production step) of bending a pair of terminals 1B.1B protruding from the hard base 4 in mutually opposite directions to obtain an assembly AS consisting of the electrolytic capacitor 1, the soft base 3, and the hard base 4, as shown in Fig. 2(D). Although not shown in the figure, the bent portion of the terminal 1B is received in the groove (4C in Fig. 1) of the hard base 4 as described above, and forms the same plane as the bottom surface of the hard base 4.

[0020] Next, the above-mentioned method for mounting an electrolytic capacitor includes a process (mounting process) of providing solder (solder material) S, S at positions corresponding to the bent portions of the terminals 1B, 1B on the substrate 2 to set the assembly AS, and heat-treating the assembly AS. Here, in Fig. 2, the assembly is shown in a position with the terminal 1B facing up, but in the processes shown in Figs. 2(E) to (G), the assembly is turned upside down with the substrate 2 shown by the imaginary line in Figs. 2(E) to (G) facing down, and heat treatment is performed using, for example, a heating furnace.

[0021] That is, the method of mounting the electrolytic capacitor involves arranging solder (solder material) S, S on the substrate 2 as shown in FIG. 2(E), setting the assembly AS as shown in FIG. 2(F), and heat-treating the assembly AS as shown in FIG. 2(G).

[0022] In the above heat treatment process, as described above, the soft base 3 is made of a material having a melting point higher than that of the solder S, so that in the process of increasing the temperature, the solder S melts first, followed by the soft base 3, as shown in the reflow time chart of Fig. 3. Then, after maintaining a constant temperature for a predetermined time, in the process of decreasing the temperature, the soft base 3 solidifies first, followed by the solder S.

[0023] At this time, in the mounting method of the electrolytic capacitor, a portion of the molten soft base 3 flows into the base through holes 4B, 4B of the hard base 4, reaches the substrate 2, and as it solidifies, is welded to the substrate 2, and both terminals 1B, 1B are soldered (S) to the substrate 2. After cooling, the mounting structure of the electrolytic capacitor shown in the lower left diagram of Figure 1 can be obtained.

[0024] According to the above-described electrolytic capacitor mounting structure and mounting method, the hard base 4 has the function of positioning and fixing the electrolytic capacitor 1 on the substrate 2, and the soft base 3 fills the gap between the substrate 2 and the hard base 4. As a result, only the terminal 1B of the electrolytic capacitor 1 and the substrate 2 are connected by the solder S, and it is possible to prevent the body 1A of the electrolytic capacitor 1 from floating.

[0025] In this way, the above-mentioned electrolytic capacitor mounting structure can improve vibration resistance, and even when subjected to repeated vibration input, can suppress stress generated in terminal 1B of electrolytic capacitor 1, making it highly useful for electronic devices mounted on vehicles, for example. Furthermore, according to the electrolytic capacitor mounting method, an electrolytic capacitor mounting structure with excellent vibration resistance can be efficiently manufactured.

[0026] Moreover, in the above-mentioned electrolytic capacitor mounting structure, the cross-sectional area of ​​the base through-hole 4B in the hard base 4 is larger than the cross-sectional area of ​​the terminal through-hole 4A. As a result, the above-mentioned electrolytic capacitor mounting structure sandwiches the electrolytic capacitor 1 in the height direction with the hard base 4, ensuring high rigidity of the soft base 3, reducing stress on the connection part of the terminal 1B by the solder S, and improving vibration resistance. Furthermore, the larger the area where the soft base 3 contacts the body 1A of the electrolytic capacitor 1, the more improved the vibration resistance effect.

[0027] Furthermore, in the above-mentioned electrolytic capacitor mounting structure, the two pedestal through-holes 4B, 4B are arranged in line-symmetric positions on the outer side with respect to the center line C passing through the two terminal through-holes 4A, 4A in a plan view of the hard base 4. As a result, in the above-mentioned electrolytic capacitor mounting structure, the soft base 3 is fixed to the board 2 on the outer side of the joint made of the solder S, making it easier for the moment force of the soft base 3 to act, thereby mitigating the stress on the connection made of the solder S and contributing to further improving vibration resistance.

[0028] Furthermore, in the above-described electrolytic capacitor mounting structure and mounting method, the soft base 3 and the solder S are melted simultaneously in a heat treatment process (reflow process). Specifically, the soft base 3 is heated to a temperature above its melting point, melting the molten base 3 and the solder S. When the temperature is then lowered below the melting point of the soft base 3, the soft base 3 solidifies. Thus, the soft base 3 functions as a positioning spacer for the solder S. When the temperature is then lowered below the melting point of the solder S, the solder S solidifies, allowing the electrolytic capacitor 1 to be mounted without impeding soldering.

[0029] Furthermore, in the above-mentioned electrolytic capacitor mounting structure and method, the body 1A of the electrolytic capacitor 1 is joined to the board by the soft seat 3 during soldering, so that it is possible to prevent the electrolytic capacitor 1 from being joined in a lifted state due to an imbalance in surface tension caused by a time difference in the melting of the solder S. As a result, the connection part by the solder S becomes a surface contact instead of a point contact at only the fixed points, and the stress on the joint can be reduced. Furthermore, in the above-mentioned electrolytic capacitor mounting structure and method, the desired structure can be formed by employing reflow to melt the solder S, so no additional equipment is required for the process.

[0030] Furthermore, in the above-mentioned electrolytic capacitor mounting structure and mounting method, the soft base 3 is made of a material having a lighter specific gravity than the solder S, so that even if part of the molten soft base 3 flows into the joint made by the solder S, it does not hinder the joining made by the solder S.

[0031] Furthermore, the above-mentioned electrolytic capacitor mounting structure and mounting method employ a soft base 3 that is more elastic than the hard base 4, thereby achieving the effect of positioning the electrolytic capacitor 1 with the hard base 4 while attenuating vibration with the soft base 3. One example of the soft base 3 is a rubber material. Furthermore, by being interposed between the body 1A of the electrolytic capacitor 1 and the hard base 4, the soft base 3 achieves further improvement in vibration resistance.

[0032] 4 is a diagram showing second to fourth embodiments of the mounting structure for an electrolytic capacitor according to the present invention. In the following embodiments, the same reference numerals are used to designate the same parts as in the first embodiment, and detailed description thereof will be omitted.

[0033] <Second embodiment> 4, in the heat treatment step of the mounting method, which is a manufacturing method of the electrolytic capacitor mounting structure, an assembly AS consisting of an electrolytic capacitor 1, a soft base 3, and a hard base 4 is held on a substrate 2 via a jig 10, as shown in the upper left diagram of the same figure. At that time, the jig 10 holds the assembly AS by forming a gap 11 between the substrate 2 and the assembly AS.

[0034] 4, in the mounting structure of the electrolytic capacitor, part of the soft base 3 that has flowed into the base through-holes 4B, 4B of the hard base 4 also flows into the gap 11 between the substrate 2 and the assembly AS and solidifies, becoming welded to the substrate 2. The terminal 1B is connected to the substrate 2 by the solder S.

[0035] In the above-described electrolytic capacitor mounting structure, as in the first embodiment, it is possible to improve vibration resistance, and even when subjected to repeated vibration input, it is possible to suppress the stress generated in the terminals of the electrolytic capacitor. In particular, the presence of a portion of the soft base 3 between the hard base 4 and the substrate 2 can contribute to further improving vibration resistance.

[0036] <Third and fourth embodiments> The lower part of Fig. 4 shows two other examples of the hard base 4. The hard base 4 shown in the lower left diagram has a pair of terminal through holes 4A, 4A, and three circular base through holes 4B are arranged in a straight line between them. The hard base 4 shown in the lower right diagram has a pair of terminal through holes 4A, 4A, and elongated base through holes 4B, 4B are arranged on both sides of a center line C connecting the two through holes 4A, 4A. The number and arrangement of the base through holes 4B in the hard base 4 can be appropriately selected other than the illustrated examples, and in any case, the same effect as the previous embodiment can be obtained.

[0037] The electrolytic capacitor mounting structure according to the present invention is not limited to the above-described embodiments, and may be modified as appropriate without departing from the gist of the present invention. [Explanation of symbols]

[0038] AS assembly S solder 1. Electrolytic capacitor 1B terminal 2. Board 3 Soft base 4 Hard base 4A terminal through hole 4B Pedestal through hole

Claims

1. A structure in which an electrolytic capacitor having terminals is mounted on a substrate, a soft base disposed on the electrolytic capacitor side and a hard base disposed on the substrate side are provided between the electrolytic capacitor and the substrate, the soft base is made of a material that is relatively soft compared to the hard base and has thermoplastic properties; A mounting structure for an electrolytic capacitor, characterized in that the terminal penetrates the soft base and the hard base and is soldered to the substrate, and a portion of the soft base penetrates the hard base and is welded to the substrate.

2. 2. The electrolytic capacitor mounting structure according to claim 1, wherein the hard base has a terminal through-hole through which the terminal passes, and a base through-hole through which a portion of the soft base passes.

3. 3. The electrolytic capacitor mounting structure according to claim 2, wherein a cross-sectional area of ​​the base through-hole in the hard base is larger than a cross-sectional area of ​​the terminal through-hole.

4. the rigid base includes at least two of the terminal through holes and at least two of the base through holes; 4. An electrolytic capacitor mounting structure as described in claim 3, characterized in that, when viewed in a plan view of the rigid base, the two base through holes are arranged in a position that is linearly symmetrical and closer to the outside than the terminal through holes with respect to a center line passing through the two terminal through holes.

5. 2. The electrolytic capacitor mounting structure according to claim 1, wherein the soft base is made of a material having a melting point higher than that of the solder that joins the terminal and the substrate.

6. 2. The electrolytic capacitor mounting structure according to claim 1, wherein the soft base is made of a material having a specific gravity lighter than that of the solder that joins the terminal and the substrate.

7. 2. The electrolytic capacitor mounting structure according to claim 1, wherein the soft base is made of an elastic material.

8. When mounting the electrolytic capacitor according to claim 1 on the substrate, a step of sequentially setting the soft base and the hard base on the electrolytic capacitor and penetrating the terminal through the soft base and the hard base; bending the terminal protruding from the hard base to obtain an assembly including the electrolytic capacitor, the soft base, and the hard base; placing solder on the bent portions of the terminals, setting the assembly on the substrate, and subjecting the assembly to a heat treatment; A method for mounting an electrolytic capacitor, characterized in that, in a heat treatment process for the assembly, the solder is melted, the terminal is soldered to the substrate, the soft base is melted, and a portion of it is passed through the hard base and welded to the substrate.

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