JP7705597B2 - Chip capacitors and their chip bases - Google Patents

Description

The present invention relates to a chip-type capacitor that enables the surface mounting of an aluminum electrolytic capacitor on a circuit board and a base plate for forming the chip, and more specifically, to a technology for suppressing the occurrence of voids and cracks caused by flux gas generated during soldering.

In a lead-in-the-same-direction aluminum electrolytic capacitor (also called a discrete type), in which a pair of lead terminals extend in the same direction from the sealing part of the exterior case in which the capacitor element is built, a synthetic resin seat plate with a pair of lead terminal insertion holes is attached to the sealing part of the exterior case, and the lead terminals that extend through the lead terminal insertion holes to the bottom side of the seat plate are bent in directions away from each other to form a chip shape, in order to enable surface mounting on a circuit board.

This type of chip capacitor is often soldered to the circuit board by the reflow soldering method, but in the case of chip capacitors for in-vehicle use, which require 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).

As is well known, flux gas (gasified flux) is generated during soldering, and if the flux gas remains in the fillet, it can cause voids and cracks. These types of voids and cracks reduce the reliability of the solder joint.

JP 2008-244033 A JP 2012-138414 A

The objective of the present invention is to suppress the occurrence of voids and cracks caused by flux gas generated during soldering in chip-type capacitors in which a seat plate for chipping (surface mounting) is attached to an aluminum electrolytic capacitor.

In order to solve the above problems, the present invention includes several characteristic aspects. First, the first aspect is a chip-type capacitor including a capacitor body having a pair of lead terminals extending in the same direction from the sealing part of a bottomed cylindrical outer case in which a capacitor element is built, and a seat plate made of synthetic resin attached to the sealing part side of the outer case, the seat plate having a pair of lead terminal insertion holes through which the lead terminals are inserted, and lead terminal storage grooves are formed on the bottom surface of the seat plate, extending from each of the lead terminal insertion holes in opposite directions away from each other to the opposing sides of the seat plate, and auxiliary terminals are embedded along each of the lead terminal storage grooves to be integrated with the lead terminals during soldering, the lead terminals are inserted into the lead terminal insertion holes, and their tip portions are stored in the lead terminal storage grooves by bending, and the chip-type capacitor is soldered together with the auxiliary terminals to a predetermined portion of a circuit board, and the auxiliary terminals are characterized in that a gas escape groove is formed in the auxiliary terminals to escape flux gas generated during soldering.

The second aspect is characterized in that the auxiliary terminal has, as a soldering portion for the circuit board, a main plate portion that is attached to the bottom surface of the seat plate during resin molding of the seat plate, leaving a surface portion, and a branch plate portion that is connected to the main plate portion and attached to the side edge of the seat plate.

The third aspect is characterized in that the gas escape groove is formed from the center of the main plate portion to the side edge of the seat plate.

The fourth aspect is characterized in that the area of the main plate portion occupied by the gas relief groove is 10 to 65% of the area of the main plate portion before the gas relief groove is formed.

The fifth aspect is characterized in that a retaining portion is formed on the component placement surface side of the seat plate, the retaining portion having a height that exceeds the horizontal groove for sealing formed in the outer case.

The present invention also includes a base plate for forming a chip of an aluminum electrolytic capacitor having same-lead direction into a surface-mountable chip form. A sixth aspect of the present invention is a base plate made of synthetic resin that is attached to the sealing part of a capacitor body having a pair of lead terminals extending in the same direction from the sealing part of a bottomed cylindrical outer case containing a capacitor element, and forms the capacitor body into a surface-mountable chip form,
a pair of lead terminal insertion holes through which the lead terminals are inserted, lead terminal storage grooves are formed in the bottom surface thereof, each extending from each of the lead terminal insertion holes in opposite directions away from each other to opposing side edges, and auxiliary terminals are embedded along each of the lead terminal storage grooves to be integrated with the lead terminals when soldered;
a seat plate for forming chips in which the lead terminals are inserted into the lead terminal insertion holes, and the tip portions of the lead terminals are accommodated in the lead terminal accommodation grooves by bending, and the auxiliary terminals are soldered together with the lead terminals to predetermined positions on a circuit board,
The auxiliary terminal is characterized in that a gas escape groove is formed for escaping flux gas generated during the soldering.

The seventh aspect is characterized in that in the seat plate for chipping according to the sixth aspect, the auxiliary terminal has a main plate portion that is attached to the bottom surface of the seat plate, leaving a surface portion when the seat plate is resin-molded, as a soldering portion for the circuit board, and a branch plate portion that is connected to the main plate portion and attached to the side edge of the seat plate.

An eighth aspect is characterized in that, in the seat plate for chipping according to the seventh aspect, the gas escape groove is formed from the central portion of the main plate portion of the auxiliary terminal to the side edge of the seat plate.

A ninth aspect is characterized in that, in the seat plate for chipping relating to the seventh aspect, the gas escape groove is formed from the central part of the main plate portion in a direction opposite to the side edge of the seat plate.

A tenth aspect is characterized in that, in the seat plate for chipping relating to the seventh aspect, the gas escape groove is formed from the central part of the main plate portion in the opposite direction to the lead terminal storage groove.

The eleventh aspect is characterized in that in the seat plate for chipping according to any one of the seventh to tenth aspects, the area of the main plate portion occupied by the gas release groove is 10 to 65% of the area of the main plate portion before the gas release groove is formed.

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

According to the present invention, in a chip-type capacitor in which a seat plate for chipping (surface mounting) is attached to an aluminum electrolytic capacitor, it is possible to suppress the occurrence of voids and cracks caused by flux gas generated during soldering.

1 is a plan view showing an embodiment of a seat plate for surface mounting a chip-type capacitor according to the present invention; FIG. 2 is a front view showing the surface mount base plate along line AA in FIG. 1 in partial cross section, together with an aluminum electrolytic capacitor; FIG. FIG. 5 is an enlarged view of a main portion of the auxiliary terminal portion of FIG. 4 . FIG. 4 is a perspective view showing an auxiliary terminal attached to the surface mounting base plate in a state where the auxiliary terminal is suspended from a hoop material. FIG. 7 is a front view of FIG.

Next, several embodiments of the present invention will be described with reference to Figures 1 to 7, but the present invention is not limited to these embodiments.

First, referring to Figures 1 to 3, particularly Figure 3, the seat plate 10 according to the present invention is used to make an aluminum electrolytic capacitor (hereinafter sometimes referred to as the "capacitor body") 1 into a chip-type capacitor that can be surface-mounted on a circuit board (not shown). This type of seat plate for chipping is also sometimes called a pedestal.

The capacitor body 1 to which this base plate 10 is applied is a lead-in-the-same-direction type (also called a discrete type) in which a pair of lead terminals 5a, 5b are pulled out in the same direction from the sealing portion 4 of the exterior case 3 in which the capacitor element 2 is built.

The outer case 3 is usually a cylindrical aluminum case with a bottom, and its opening is closed by a rubber seal 6 made of, for example, butyl rubber, which serves as the sealing portion 4. To increase the airtightness of the sealing portion 4, a horizontal squeeze groove 7 is formed in the circumferential direction on the outer periphery of the outer case 3 along the rubber seal 6.

In this example, lead terminal 5a is the anode side and lead terminal 5b is the cathode side, both of which penetrate the rubber seal 6 and are pulled out to the outside. When there is no need to distinguish between lead terminals 5a and 5b, they are collectively referred to as lead terminal 5.

The seat plate 10 is rectangular in shape with two adjacent corners cut off at an angle in the plan view of FIG. 1, and is made entirely of heat-resistant synthetic resin. FIG. 1 shows the component mounting surface 10a side of the seat plate 10 on which the capacitor body 1 is placed, and FIG. 4 shows the bottom surface 10b side of the seat plate 10 that faces a circuit board (not shown) during soldering.

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

Lead terminal storage grooves 12a, 12b are formed on the bottom surface 10b of the seat plate 10, extending from each lead terminal insertion hole 11a, 11b in opposite directions away from each other to the opposing side edges 13a, 13b of the seat plate 10. When there is no need to distinguish between the lead terminal storage grooves 12a, 12b, they are collectively referred to as lead terminal storage groove 12. When there is no need to distinguish between the side edges 13a, 13b, they are collectively referred to as side edges 13.

The capacitor body 1 is placed on the component mounting surface 10a of the seat plate 10 while the lead terminals 5a and 5b are inserted into the lead terminal insertion holes 11a and 11b, and then 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, thereby forming the capacitor body 1 into a chip-type capacitor 1A that can be surface-mounted on a circuit board.

Mounting to the circuit board is often performed by reflow soldering, but auxiliary terminals 20 are used to increase the soldering strength (mounting strength). 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 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.

Each auxiliary terminal 20 is preferably embedded integrally in the seat plate 10 by insert molding within the mold. Therefore, as shown in Figures 6 and 7, each auxiliary terminal 20 is carried into the mold in a state where it is supported as a pair of auxiliary terminals 20a, 20b by the hoop material 40 for each lead terminal storage groove 12a, 12b. When supported by the hoop material 40, the auxiliary terminals 20a and 20b are symmetrical.

The auxiliary terminal 20 has a main plate portion 21 that occupies the majority of the auxiliary terminal 20. The main plate portion 21 is attached (embedded) to the side of the lead terminal storage groove 12 on the bottom surface 10b of the seat plate 10 so that the surface is exposed.

A flange piece 22 is formed on one side edge of the main plate portion 21 facing the lead terminal storage groove 12, rising from the main plate portion 21 at a substantially right angle so as to be exposed in the lead terminal storage groove 12. A hole 221 is drilled in the flange piece 22, into which the resin enters during injection molding.

An anchor piece 23 is bent diagonally upward so as to fit into the seat plate 10 and is connected to the side edge of the main plate portion 21 opposite the one side edge mentioned above. The anchor piece 23 also has a hole 231 through which the resin enters during injection molding.

The main plate portion 21 is formed with a gas escape groove 24 for escaping flux gas generated during soldering. This gas escape groove 24 is preferably a slit, but may also be a gutter-shaped groove with a groove bottom. Also, there may be multiple gas escape grooves 24.

In this embodiment, the gas escape groove 24 is formed from the center of the main plate portion 21 to the side edge 113 (13a, 13b) of the seat plate 10. It is preferable that the area of the main plate portion 21 occupied by the gas escape groove 24 is 10 to 65% of the area of the main plate portion 21 before the gas escape groove 24 is formed.

In this embodiment, the area of the gas release groove 24 relative to the main plate portion 21 is approximately 20%, but it is preferable to optimize the ratio of the area of the gas release groove 24 relative to the main plate portion 21 depending on the size of the seat plate 10, etc. Also, in this embodiment, the end of the gas release groove 24 is open toward the side edge 13 of the seat plate 10, but the gas release groove 24 may be formed toward the opposite side (the right side in FIG. 5) or toward the side not to which solder is attached (the lower side in FIG. 5).

The main plate portion 21 is bifurcated at the side edge 13 of the seat plate 10 by the gas release groove 24, and of the branch pieces 25a and 25b, the branch piece 25b that is farther from the lead terminal storage groove 12 is provided with a branch plate portion 26. The branch plate portion 26 is bent at a right angle from the branch piece 25b so as to fit along the side piece 13 of the seat plate 10. The branch plate portion 26 may be formed on the branch piece 25a side. The main plate portion 21 and the branch plate portion 26 are the soldering portion of the auxiliary terminal 20 to the circuit board.

The auxiliary terminals 20 (20a, 20b) are separated from the hoop material 40 at the portion indicated by the two-dot chain line DL in Figures 6 and 7 after being fitted into the mold or after injection molding, and the branch plate portion 26 is attached (embedded) in the side edge 13 of the seat plate 10 for the most part so that the surface is exposed when the seat plate 10 is injection molded. In this way, the auxiliary terminals 20 are attached to both sides of the lead terminal storage grooves 12a, 12b on the bottom surface 10b of the seat plate 10.

When this chip-type capacitor 1A is attached to a circuit board (not shown), for example by reflow soldering, the lead terminal 5 and auxiliary terminal 20 are integrated by the molten solder and soldered to the land portion of the circuit board, and the solder creeps up along the branch plate portion 26, so that the capacitor is firmly attached to the circuit board. In addition, the flux gas generated at this time is released through the gas escape groove 24, so that the occurrence of voids and cracks in the soldered portion can be suppressed.

On the other hand, a holding portion 30 is provided on the component mounting surface 10a side of the seat plate 10 to prevent the capacitor body 1 from rattling. In this embodiment, the holding portion 30 is formed as a support pillar 31 erected at each of the four corners of the seat plate 10 so as to contact the outer case 3. Each support pillar 31 has a height that exceeds at least the horizontal groove 7 for sealing formed in the outer case 3.

In addition, for polarity determination, of the four pillars 31a to 31d, the cathode side pillars 31c and 31d are made lower in height than the anode side pillars 31a and 31b. Conversely, the cathode side pillars 31c and 31d may be made higher than the anode side pillars 31a and 31b. Referring to Figures 1 and 4, the two adjacent corners 10c and 10d of the seat plate 10 are cut off at an angle to make polarity determination easier.

As another example of the retaining portion 30, the retaining portion 30 may be a cylindrical wall that surrounds the outer case 3, provided that its height exceeds the horizontal groove 7 for sealing.

The present invention has been described above using an embodiment, but the technical scope of the present invention is not limited to the description of the above embodiment. Modifications or improvements made to the above embodiment by those skilled in the art are also included in the technical scope of the present invention.

REFERENCE SIGNS LIST 1 Capacitor body 1A Chip capacitor 2 Capacitor element 3 Outer case 4 Sealing portion 5 (5a, 5b) Lead terminal 6 Rubber sealing body 7 Horizontal drawing 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 edge 20 (20a, 20b) Auxiliary terminal 21 Main plate portion 22 Flange piece 23 Anchor piece 24 Gas release groove 26 Branch plate portion 30 Holding portion 31 (31a to 31d) Support

Claims (12)

The capacitor includes a capacitor body having a pair of lead terminals extending in the same direction from a sealing portion of a bottomed cylindrical outer case in which a capacitor element is built, and a synthetic resin base plate attached to the sealing portion side of the outer case,
the seat plate has a pair of lead terminal insertion holes through which the lead terminals are inserted, and lead terminal storage grooves are formed in a bottom surface of the seat plate, each extending from each of the lead terminal insertion holes in opposite directions away from each other to opposite sides of the seat plate, and auxiliary terminals are embedded along each of the lead terminal storage grooves to be integrated with the lead terminals when soldered,
In a chip capacitor in which each of the lead terminals is inserted into the lead terminal insertion holes, and the tip portions of the lead terminals are bent to be accommodated in the lead terminal accommodation grooves, and the lead terminals are soldered together with the auxiliary terminals to predetermined portions of a circuit board,
a gas escape groove for escaping flux gas generated during soldering, said auxiliary terminal being formed with said gas escape groove; The chip capacitor according to claim 1, characterized in that the auxiliary terminal is provided with a main plate portion that is attached to the bottom surface of the seat plate, leaving a surface portion when the seat plate is resin-molded, as a soldering portion for the circuit board, and a branch plate portion that is connected to the main plate portion and attached to the 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 plate portion to a side edge of the base plate.
The chip capacitor described in claim 3, characterized in that the area of the main plate portion occupied by the gas relief groove is 10 to 65% of the area of the main plate portion before the gas relief groove is formed. The chip capacitor according to any one of claims 1 to 4, characterized in that a holding portion having a height exceeding the horizontal groove for sealing formed in the outer case is formed on the component mounting surface side of the seat plate. A base plate made of synthetic resin is attached to a sealing portion of a capacitor body having a pair of lead terminals extending in the same direction from a sealing portion of a bottomed cylindrical exterior case containing a capacitor element, and the base plate forms the capacitor body into a surface-mountable chip type,
a pair of lead terminal insertion holes through which the lead terminals are inserted, lead terminal storage grooves are formed in the bottom surface thereof, each extending from each of the lead terminal insertion holes in opposite directions away from each other to opposing side edges, and auxiliary terminals are embedded along each of the lead terminal storage grooves to be integrated with the lead terminals when soldered;
a seat plate for forming chips in which the lead terminals are inserted into the lead terminal insertion holes, and the tip portions of the lead terminals are accommodated in the lead terminal accommodation grooves by bending, and the auxiliary terminals are soldered together with the lead terminals to predetermined positions on a circuit board,
A seat plate for chipping, characterized in that the auxiliary terminal is formed with a gas escape groove for escaping flux gas generated during the soldering. The seat plate for chipping according to claim 6, characterized in that the auxiliary terminal comprises a main plate portion that is attached to the bottom surface of the seat plate, leaving a surface portion when the seat plate is resin-molded, as a soldering portion for the circuit board, and a branch plate portion that is connected to the main plate portion and attached to the side edge of the seat plate. 8. The base plate for chipping according to claim 7 , wherein the gas escape groove is formed from a central portion of the main plate portion to a side edge of the base plate.
8. The seat plate for chipping according to claim 7 , wherein the gas escape groove is formed from a central portion of the main plate portion toward a direction opposite to a side edge of the seat plate.
8. The seat plate for forming chips according to claim 7 , wherein the gas release groove is formed from the center of the main plate portion in a direction opposite to the lead terminal storage groove.
A seat plate for chipping according to any one of claims 7 to 10, characterized in that the area of the main plate portion occupied by the gas relief groove is 10 to 65% of the area of the main plate portion before the gas relief groove is formed. The seat plate for chipping according to any one of claims 6 to 11, characterized in that a holding portion having a height exceeding the horizontal groove for sealing formed in the outer case is formed on the component mounting surface side of the seat plate.

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