Chip capacitor and seat plate for chip formation thereof

Abstract

To suppress the generation of voids and cracks due to flux gas generated during soldering in a chip capacitor having a base plate attached to the capacitor.SOLUTION: In providing an auxiliary terminal 20 for enhancing the soldering strength on a base plate 10 for chip formation that enables surface mounting of the capacitors with the same lead direction, the auxiliary terminal 20 is preferably formed with a gas escape groove 24 consisting of a slit for releasing flux gas generated at the time of soldering.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a chip capacitor that enables surface mounting of an aluminum electrolytic capacitor on a circuit board and a seat plate for chip formation thereof. More specifically, it relates to a technique for suppressing the generation of voids and cracks caused by flux gas generated during soldering.

Background Art

[0002] In a lead-same-direction type (also referred to as a discrete type) aluminum electrolytic capacitor in which a pair of lead terminals are drawn out in the same direction from the sealing portion of an exterior case containing a capacitor element, in order to enable surface mounting on a circuit board, a synthetic resin seat plate having a pair of lead terminal insertion holes is attached to the sealing portion side of the exterior case, and the lead terminals drawn out to the bottom side of the seat plate through the lead terminal insertion holes are bent in directions away from each other to form a chip shape.

[0003] This type of chip capacitor is often soldered to a circuit board by the reflow soldering method. In particular, in a chip capacitor for in-vehicle use that requires particularly high vibration resistance, auxiliary terminals are provided on the bottom surface of the seat plate to increase the soldering strength (see, for example, Patent Documents 1 and 2).

[0004] As is well known, flux gas (gasified flux) is generated during soldering, and voids and cracks may occur when the flux gas remains in the fillet. This type of void and crack impairs the reliability of the solder connection.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to suppress the generation of voids and cracks caused by flux gas during soldering in a chip capacitor formed by attaching a mounting plate (for surface mounting) to an aluminum electrolytic capacitor.

Means for Solving the Problems

[0007] To solve the above problems, the present invention includes several characteristic aspects. First, a first aspect includes a capacitor body in which a pair of lead terminals are drawn out in the same direction from a sealed portion of a bottomed cylindrical exterior case containing a capacitor element, and a synthetic resin mounting plate mounted on the sealed portion side of the exterior case. The mounting plate has a pair of lead terminal insertion holes through which the lead terminals are inserted. On the bottom surface of the mounting plate, lead terminal storage grooves are formed extending from each lead terminal insertion hole in opposite directions away from each other to the opposing side edges of the mounting plate. Along each lead terminal storage groove, auxiliary terminals integrated with the lead terminals during soldering are embedded. In a chip capacitor in which each lead terminal is inserted through the lead terminal insertion hole and their tip portions are housed in the lead terminal storage grooves by bending and are soldered to a predetermined portion of a circuit board together with the auxiliary terminals, a gas escape groove for escaping flux gas generated during soldering is formed in the auxiliary terminal.

[0008] A second aspect is characterized in that the auxiliary terminal includes a main board portion attached to the bottom surface of the mounting plate while leaving a surface portion during resin molding of the mounting plate as a soldering portion to the circuit board, and a branch board portion connected to the main board portion and attached to the side edge of the mounting plate.

[0009] A third aspect is characterized in that the gas escape groove is formed from the central portion of the main board portion to the side edge of the mounting plate.

[0010] In the fourth aspect, the area occupied by the gas escape groove in the main board portion is 10 to 65% of the area of the main board portion before the gas escape groove is formed.

[0011] In the fifth aspect, on the component mounting surface side of the seat plate, a holding portion having a height exceeding the horizontal constriction groove for sealing formed in the exterior case is formed.

[0012] The present invention also includes a seat plate for chip formation that makes a lead same-direction type aluminum electrolytic capacitor into a surface-mountable chip shape. The sixth aspect is a synthetic resin seat plate that is mounted on the sealing portion side of a capacitor body in which a pair of lead terminals are drawn out in the same direction from the sealing portion of a bottomed cylindrical exterior case in which a capacitor element is incorporated, and that makes the capacitor body into a surface-mountable chip shape, which has a pair of lead terminal insertion holes through which the lead terminals are inserted, and on the bottom surface, lead terminal storage grooves are formed that extend from each of the lead terminal insertion holes to opposing side edges in opposite directions away from each other, and auxiliary terminals that are integrated with the lead terminals during soldering are embedded along each of the lead terminal storage grooves, in a seat plate for chip formation in which each of the lead terminals is inserted into the lead terminal insertion hole, and their tip portions are housed in the lead terminal storage groove by bending, and the auxiliary terminals are soldered to a predetermined portion of a circuit board together with the lead terminals, characterized in that gas escape grooves for escaping flux gas generated during soldering are formed in the auxiliary terminals.

[0013] In the seventh aspect, in the seat plate for chip formation according to the sixth aspect, the auxiliary terminal includes a main board portion that is attached to the bottom surface of the seat plate leaving the surface portion during resin molding of the seat plate as a soldering portion to the circuit board, and a branch board portion that is connected to the main board portion and is attached to the side of the seat plate.

[0014] The eighth aspect is in the seat plate for chip formation according to the above 7th aspect, wherein the gas escape groove is formed from the central portion of the main board portion of the auxiliary terminal to the side of the seat plate.

[0015] The ninth aspect is in the seat plate for chip formation according to the above of 7 aspect, wherein the gas escape groove is formed from the central portion of the main board portion in a direction opposite to the side of the seat plate.

[0016] The tenth aspect is in the seat plate for chip formation according to the above of 7 aspect, wherein the gas escape groove is formed from the central portion of the main board portion in a direction opposite to the lead terminal storage groove.

[0017] The eleventh aspect is in the seat plate for chip formation according to any one of the seventh to tenth aspects, wherein the area occupied by the gas escape groove in the main board portion is 10 to 65% of the area of the main board portion before the gas escape groove is formed.

[0018] Further, the twelfth aspect is in the surface mounting seat plate for the chip capacitor according to any one of the sixth to eleventh aspects, wherein a holding portion having a height exceeding the horizontal constriction groove for sealing formed in the outer case is formed on the component mounting surface side of the seat plate.

Advantages of the Invention

[0019] According to the present invention, in a chip capacitor formed by attaching a seat plate for chip formation (surface mounting) to an aluminum electrolytic capacitor, it is possible to suppress the generation of voids and cracks due to flux gas generated during soldering.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0021] Next, some embodiments of the present invention will be described with reference to FIGS. 1 to 7, but the present invention is not limited to these embodiments.

[0022] First, referring particularly to FIG. 3 among FIGS. 1 to 3, the base plate 10 according to the present invention is a chip capacitor configured to be surface-mounted on a circuit board (not shown) or the like for an aluminum electrolytic capacitor (hereinafter sometimes referred to as "capacitor body") 1. Note that this type of base plate for chip formation is sometimes called a pedestal.

[0023] The capacitor body 1 to which this base plate 10 is applied has a lead same direction type (also called a discrete type) in which a pair of lead terminals 5a and 5b are drawn out in the same direction from a sealing portion 4 of an exterior case 3 in which a capacitor element 2 is incorporated.

[0024] Normally, the exterior case 3 is a bottomed cylindrical shape made of aluminum, and its opening is closed by a rubber sealing body 6 made of, for example, butyl rubber as the sealing portion 4. In order to enhance the airtightness of the sealing portion 4, a circumferential constriction groove 7 is formed in the circumferential direction along the rubber sealing body 6 on the outer peripheral surface of the exterior case 3.

[0025] In this example, the lead terminal 5a is on the anode side, the lead terminal 5b is on the cathode side, and both penetrate through the rubber sealing body 6 and are drawn out to the outside. When it is not necessary to distinguish between the lead terminals 5a and 5b, they are collectively referred to as the lead terminal 5.

[0026] The seat plate 10 is in a rectangular shape with two adjacent corners cut off diagonally in the plan view of FIG. 1 and is entirely made of a heat-resistant synthetic resin. FIG. 1 shows the component mounting surface 10a side of the seat plate 10 where the capacitor body 1 is placed, and FIG. 4 shows the bottom surface 10b side of the seat plate 10 facing a circuit board (not shown) during soldering.

[0027] A pair of lead terminal insertion holes 11a and 11b through which the lead terminals 5a and 5b are inserted are formed in the seat plate 10. When it is not necessary to distinguish between the lead terminal insertion holes 11a and 11b, they are collectively referred to as the lead terminal insertion hole 11.

[0028] On the bottom surface 10b of the seat plate 10, lead terminal storage grooves 12a and 12b extending from the respective lead terminal insertion holes 11a and 11b in opposite directions away from each other to the opposing side edges 13a and 13b of the seat plate 10 are formed. Regarding the lead terminal storage grooves 12a and 12b, when it is not necessary to distinguish them, they are collectively referred to as the lead terminal storage groove 12. Also, regarding the side edges 13a and 13b, when it is not necessary to distinguish them, they are collectively referred to as the side edge 13.

[0029] While inserting the lead terminals 5a and 5b into the lead terminal insertion holes 11a and 11b, after placing the capacitor body 1 on the component mounting surface 10a of the seat plate 10, the lead terminals 5a and 5b are bent in opposite directions away from each other and stored in the lead terminal storage grooves 12a and 12b, whereby the capacitor body 1 can be made into a chip-type capacitor 1A that can be surface-mounted on a circuit board.

[0030] The mounting on the circuit board is often performed by reflow soldering. However, in order to increase the soldering strength (mounting strength), the auxiliary terminals 20 are used. In this embodiment, the auxiliary terminals 20 are provided at a total of four locations on both sides of the lead terminal storage groove 12a and on both sides of the lead terminal storage groove 12b, and are integrated with the lead terminals 5 by the solder material during soldering. In this embodiment, the auxiliary terminals 20 are made of brass.

[0031] Each auxiliary terminal 20 is preferably integrally embedded in the seat plate 10 by insert molding within the mold. Therefore, as shown in FIGS. 6 and 7, each auxiliary terminal 20 is carried into the mold in a state of being supported as a pair of auxiliary terminals 20a and 20b by the hoop material 40 for each of the lead terminal storage grooves 12a and 12b. In the state of being supported by the hoop material 40, the auxiliary terminal 20a and the auxiliary terminal 20b are symmetric about the left and right.

[0032] The auxiliary terminal 20 includes a main board portion 21 that occupies most of the auxiliary terminal 20. The main board portion 21 is attached (embedded) beside the lead terminal storage groove 12 on the bottom surface 10b of the seat plate 10 so that the surface is exposed.

[0033] On one side edge of the main board portion 21 facing the lead terminal storage groove 12, a flange piece 22 is formed that stands up from the main board portion 21 at a substantially right angle so as to be exposed within the lead terminal storage groove 12. A hole 221 through which resin enters during injection molding is formed in the flange piece 22.

[0034] On the side edge of the main board portion 21 opposite to the one side edge, an anchor piece 23 is continuously provided that is bent obliquely upward so as to bite into the seat plate 10. A hole 231 through which resin enters during injection molding is also formed in the anchor piece 23.

[0035] A gas escape groove 24 is formed in the main board portion 21 to release the flux gas generated during soldering. This gas escape groove 24 is preferably a slit, but may also be a trough-shaped with a groove bottom. Also, there may be a plurality of gas escape grooves 24.

[0036] In this embodiment, the gas escape groove 24 is formed from the central portion of the main board portion 21 to the side 113 (13a, 13b) of the seat plate 10. The area occupied by the gas escape groove 24 in the main board portion 21 is preferably 10 to 65% of the area of the main board portion 21 before the gas escape groove 24 is formed.

[0037] In this embodiment, the area occupied by the gas escape groove 24 with respect to the main board portion 21 is about 20%, but the ratio of the area occupied by the gas escape groove 24 with respect to the main board portion 21 is preferably optimized according to the size of the seat plate 10 and the like. Further, in this embodiment, the end of the gas escape groove 24 is open toward the side 13 of the seat plate 10, but the gas escape groove 24 may be formed toward the opposite side (the right side in FIG. 5) or toward the side where no solder is attached (the lower side in FIG. 5).

[0038] The side 13 side of the seat plate 10 of the main board portion 21 is bifurcated by the gas escape groove 24. Among the bifurcated pieces 25a and 25b, a branch board portion 26 is provided on the bifurcated piece 25b that is farther away from the lead terminal storage groove 12. The branch board portion 26 is bent at a right angle from the bifurcated piece 25b along the side piece 13 of the seat plate 10. Note that the branch board portion 26 may be formed on the bifurcated piece 25a side. The main board portion 21 and the branch board portion 26 serve as the soldering portions of the auxiliary terminals 20 for the circuit board.

[0039] The auxiliary terminals 20 (20a, 20b) are separated from the hoop material 40 at the portion of the two-dot chain line DL in FIGS. 6 and 7 after being mounted in the gold form or after injection molding. Most of the branch board portion 26 is attached (embedded) to the side 13 of the seat plate 10 so that its surface is exposed during the injection molding of the seat plate 10. In this way, the auxiliary terminals 20 are respectively attached to both sides of the lead terminal storage grooves 12a and 12b on the bottom surface 10b of the seat plate 10.

[0040] When mounting this chip capacitor 1A on a circuit board (not shown) by, for example, the reflow soldering method, the molten solder integrates the lead terminal 5 and the auxiliary terminal 20 and solders them to the land portion of the circuit board. Also, since the solder crawls along the branch plate portion 26, it is firmly attached to the circuit board. Further, since the flux gas generated at that time is released from the gas escape groove 24, it is possible to suppress the occurrence of voids and cracks in the soldered portion.

[0041] On the other hand, on the component mounting surface 10a side of the seat plate 10, a holding portion 30 for suppressing the rattling of the capacitor body 1 is provided. In this embodiment, the holding portion 30 is formed as columns 31 erected at the four corners of the seat plate 10 so as to contact the exterior case 3. Each column 31 has a height exceeding at least the horizontal constriction groove 7 for sealing formed in the exterior case 3.

[0042] Also, for polarity discrimination, among the four columns 31a to 31d, the columns 31c and 31d on the cathode side are made lower in height than the columns 31a and 31b on the anode side. Conversely, the columns 31c and 31d on the cathode side may be made higher than the columns 31a and 31b on the anode side. Referring to FIGS. 1 and 4, two adjacent corner portions 10c and 10d of the seat plate 10 are cut off obliquely also for facilitating polarity discrimination.

[0043] Note that, as another example of the holding portion 30, the holding portion 30 may be a cylindrical wall surrounding the exterior case 3 on the condition that the height exceeds the height of the horizontal constriction groove 7 for sealing.

[0044] As described above, the present invention has been described using embodiments, but the technical scope of the present invention is not limited to the description of the above embodiments. Modifications or improvements added to the above embodiments by those skilled in the art are also included in the technical scope of the present invention.

Description of Reference Numerals

[0045] 1 Capacitor body 1A Chip capacitor 2 Capacitor element 3 Exterior case 4 Sealing part 5(5a, 5b) Lead terminal 6 Rubber sealing body 7 Transverse constriction groove 10 Seat plate 10a Component mounting surface 10b Bottom surface 11(11a, 11b) Lead terminal insertion hole 12(12a, 12b) Lead terminal storage groove 13(13a, 13b) Side 20(20a, 20b) Auxiliary terminal 21 Main board part 22 Flange piece 23 Anchor piece 24 Gas escape groove 26 Branch board part 30 Holding part 31(31a~31d) Support pillar

Claims

1. A chip capacitor including a capacitor body in which a pair of lead terminals are drawn out in the same direction from a sealed portion of a bottomed cylindrical exterior case containing a capacitor element, and a synthetic resin seat plate mounted on the sealed portion side of the exterior case, wherein the seat plate has a pair of lead terminal insertion holes through which the lead terminals are inserted, and on the bottom surface of the seat plate, lead terminal storage grooves extending from the respective lead terminal insertion holes in opposite directions away from each other to opposite side edges of the seat plate are formed, and auxiliary terminals integrated with the lead terminals during soldering are embedded along the respective lead terminal storage grooves, wherein the respective lead terminals are inserted through the lead terminal insertion holes, and their tip portions are housed in the lead terminal storage grooves by bending, and in the chip capacitor soldered to a predetermined portion of a circuit board together with the auxiliary terminals, a chip capacitor, characterized in that the auxiliary terminal is formed with a gas escape groove for escaping flux gas generated during soldering.

2. The chip capacitor according to claim 1, wherein the auxiliary terminal includes a main board portion attached to the bottom surface of the seat plate while leaving a surface portion during resin molding of the seat plate as a soldering portion to the circuit board, and a branch board portion connected to the main board portion and attached to a side edge of the seat plate.

3. The chip capacitor according to claim 2, wherein the gas escape groove is formed from a central portion of the main board portion to a side edge of the seat plate.

4. The chip capacitor according to claim 3, wherein an area occupied by the gas escape groove in the main board portion is 10 to 65% of an area of the main board portion before the gas escape groove is formed.

5. The chip capacitor according to any one of claims 1 to 4, characterized in that a holding portion having a height exceeding a lateral constriction groove for sealing formed in the exterior case is formed on a component mounting surface side of the seat plate.

6. A synthetic resin seat plate mounted on a sealed portion side of a capacitor body in which a pair of lead terminals are drawn out in the same direction from a sealed portion of a bottomed cylindrical exterior case containing a capacitor element, and the chip-shaped capacitor body is surface mountable, It has a pair of lead terminal insertion holes through which the above lead terminals are inserted, and on the bottom surface, lead terminal storage grooves are formed that extend from each of the above lead terminal insertion holes to the opposing side edges in opposite directions away from each other. Along each of the above lead terminal storage grooves, auxiliary terminals that are integrated with the above lead terminals during soldering are embedded. In the chip-forming seat plate where each of the above lead terminals is inserted into the above lead terminal insertion holes, and their tip portions are housed in the above lead terminal storage grooves by bending, and the above auxiliary terminals are soldered together with the above lead terminals to a predetermined part of the circuit board. The chip-forming seat plate is characterized in that the above auxiliary terminals are formed with gas escape grooves for escaping the flux gas generated during soldering.

7. The above auxiliary terminal, as a soldering part to the above circuit board, includes a main board part that is attached to the bottom surface of the above seat plate while leaving the surface part during resin molding of the above seat plate, and a branch board part that is connected to the above main board part and is attached to the side of the above seat plate. The chip-forming seat plate according to claim 6 is characterized by this.

8. The chip-forming seat plate according to claim 7 is characterized in that the above gas escape groove is formed from the central part of the above main board part to the side of the above seat plate.

9. The chip-forming seat plate according to claim 7 is characterized in that the above gas escape groove is formed from the central part of the above main board part in a direction opposite to the side of the above seat plate.

10. The chip-forming seat plate according to claim 7 is characterized in that the above gas escape groove is formed from the central part of the above main board part in a direction opposite to the above lead terminal storage groove.

11. The chip-forming seat plate according to any one of claims 7 to 10 is characterized in that the area occupied by the above gas escape groove in the above main board part is 10 to 65% of the area of the above main board part before the above gas escape groove is formed.

12. The chip-forming seat plate according to any one of claims 6 to 11 is characterized in that on the component mounting surface side of the above seat plate, a holding part is formed that has a height exceeding the lateral constriction groove for sealing formed in the above exterior case.

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