JP7300897B2 - case mold type capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a case-molded capacitor in which a main part of a capacitor, in which a busbar is pulled out from a capacitor element, is housed in an exterior case and molded with resin.

In a case mold type capacitor, one end (base side) of a bus bar for external connection is connected to a pair of positive and negative electrodes of a capacitor element, and the capacitor element and part of the bus bar are accommodated in an exterior case. One ends of the capacitor element and the bus bar are embedded in the molded resin filled and solidified in the exterior case, and the other ends are pulled out from the molded resin to form external connection terminal portions.

Japanese Patent Application Laid-Open No. 2010-129573 (Patent No. 5257677)

At least one of the pair of bus bars has a relationship in which a portion of the bus bar is arranged close to the side wall plate of the exterior case, causing capillary action in the minute gap between the bus bar and the side wall plate of the case, causing the liquid filling resin to flow out. It tends to leak out.

If the clearance (distance) in the area where the external connection terminal portion of the bus bar faces the upper end surface of the side wall plate of the case is small enough to cause capillary action, the filling resin will overflow violently, and the outside of the exterior case will be exposed. There is a problem that a certain jig or the like becomes unusable due to adhesion and solidification of filled resin that overflows.

The above problem can be avoided by securing a large clearance, but on the other hand, the bus bar becomes longer than necessary, and circuit characteristics such as switching speed deteriorate due to the increase in height (larger size in the vertical direction). There has been a problem of causing an increase in inductance leading to

In order to reduce the size of the capacitor in order to reduce the inductance, it is necessary to minimize the clearance between the upper end of the case and the bus bar. However, if the clearance is made small, the filling resin will creep up along the rising plate of the busbar due to capillary action during resin injection and leak out of the case, causing the filling resin to adhere and solidify to jigs near the outside of the exterior case. may become unusable. Therefore, a structure for receiving the leaking filling resin is required.

In Patent Document 1, a resin-receiving groove is provided inside the thickness of the side wall plate of the exterior case, and the filling resin is drawn into the resin-receiving groove by utilizing capillary action. The resin-receiving groove is formed in a portion of the case side wall plate where the external connection terminal portion and the case side wall plate intersect with each other. With this structure, the filling resin sucked up into the minute gap between the external connection terminal and the side wall plate of the case by using capillary action is guided into the resin receiving groove by subsequent capillary action. ing.

However, if the resin receiving groove is provided inside the thickness of the case side wall plate, the thickness of the case side wall plate will inevitably increase. There is concern about the occurrence of sink marks (depressions on the surface of the molded body) and voids (non-impregnated portions). That is, the solid thickness of the case side wall plate is thicker in the region without the hollow resin receiving groove. If the wall thickness is large, the space volume into which the filling resin should enter will be enlarged, but if the volume is too large, the filling resin will not reach every corner, and sink marks and voids will occur. In the area with the resin receiving groove, the partial mold (insert) that enters the space (that is, the resin receiving groove) formed between the opposing double-walled thin plates is considerably thin. The strength of the mold is weak, and the mold is easily damaged and has low durability.

The present invention has been made in view of such circumstances, and the case mold type capacitor has the following features: [1] prevention of overflow of filling resin sucked up by capillary action; The purpose is to make it possible to achieve both the antinomy (conventional recognition) of promotion of low inductance.

The present invention solves the above problems by taking the following measures.

A case-molded capacitor according to the present invention comprises:
A main part of a capacitor formed by connecting a pair of busbars to metal electrodes at both ends of a capacitor element is housed in an exterior case having an opening, and the base sides of the capacitor element and the pair of busbars are filled in the exterior case with molding resin. a case mold type capacitor in which the free end sides of the pair of bus bars extend outside the exterior case,
at least one of the pair of bus bars extends along the inner side surface of the case side wall plate of the exterior case, bends and extends outside the case along the upper end surface of the case side wall plate,
Sucked up by capillary action in a minute gap between the at least one bus bar and the inner surface of the case side wall plate, the upper end surface of the case side wall plate and the at least the upper end surface of the case side wall plate are sucked up at a position corresponding to the outer surface of the case side wall plate. A resin reservoir for receiving filling resin that leaks and flows down from a gap facing one of the bus bars is provided on the case side wall plate in a posture facing outward from the outer surface of the case side wall plate. and

According to the above configuration of the present invention, the following effects are exhibited.

"At least one of the busbars" in the above is a busbar in which the filling resin injected and filled in the outer case causes a sucking effect due to capillary action in a minute gap between the relevant busbar and the inner surface of the side wall plate of the case. be. The busbars are further bent to extend out of the case along the upper end surfaces of the case side wall plates, and the filling resin leaks from the facing gaps between the upper end surfaces of the case side wall plates and the busbars and flows down. The filling resin that flows down is received by the resin reservoir.

Since the leaked filling resin is received by the resin reservoir in this way, it is possible to avoid the inconvenience that jigs and the like near the outside of the exterior case become unusable due to adhesion and solidification of the filling resin.

On the other hand, since the clearance of the busbar to the upper end surface of the side wall plate of the case is made sufficiently small to realize a low profile, it is possible to satisfy both the miniaturization of the case mold type capacitor and the reduction in inductance by shortening the busbar. becomes.

Furthermore, the resin reservoir functioning to receive the filling resin flowing down is provided in a posture facing outward from the outer surface of the case side wall plate, so that the thickness of the case side wall plate itself does not increase. Therefore, as a secondary effect, it is effective in suppressing the occurrence of sink marks and voids in the molding resin due to the thick plate when injection molding the exterior case itself (the side wall of the case when forming the resin reservoir) (Because there is no need to increase the thickness of the plate more than necessary). For the same reason, it is possible to prevent insufficient strength of component parts such as inserts and cores of the molding die, which is advantageous in ensuring the durability of the die.

The case mold type capacitor of the present invention having the above configuration has the following preferred aspects and variations/modifications.

[1] There is a mode that the resin reservoir is formed so as to extend in the horizontal direction corresponding to the region where the at least one bus bar faces the upper end surface of the case side wall plate. According to this configuration, even if the filling resin flows down from any position in the facing gap, it can be reliably received by the resin reservoir.

[2] There is a mode in which the exterior case is a molded resin body, and the resin reservoir is formed integrally with the side wall plate of the case by the same molded resin body.

In this method, when the resin reservoir is provided on the case side wall plate of the outer case, the entire outer case with the resin reservoir is formed integrally by resin injection molding. Since the resin reservoir is provided in a position facing outward from the outer surface of the case side wall plate, compared to the conventional case in which the resin receiving groove is recessed into the thick inside of the case side wall plate, the resin reservoir is provided. The structure and shape of the exterior case as a whole are simpler, which is advantageous in facilitating the manufacture of the exterior case with the resin reservoir.

[3] Further, there is a mode in which the resin reservoir portion is formed of a plate-like body, and the tip portion of the plate-like body is positioned at a position higher than the root portion to the side wall plate of the case. In this case, it is more preferable that the thickness of the plate-like body constituting the resin reservoir is substantially equal to or slightly smaller than the thickness of the side wall plate of the case.

When the resin reservoir is formed in the external case, the tip portion is made higher than the root portion, thereby simplifying the shape and structure, and ensuring that the filling resin that flows down can be accumulated in the resin reservoir. . As a result, the entire external case, including the case side wall plate and the resin reservoir, can be easily formed integrally by resin injection molding while preventing the filling resin from flowing out of the resin reservoir.

The height position of the resin reservoir on the side wall plate of the case may be determined arbitrarily. That is, the resin reservoir portion may be provided on the upper end side including the position near the lower end of the upper end surface of the case side wall plate, or may be provided at a substantially intermediate position between the upper and lower widths of the case side wall plate, or on the case side wall. It may be provided near the lower end of the plate.

In addition, the pair of bus bars are arranged parallel to each other in a state of being close to each other, and a sheet-like insulating material is inserted and interposed in the opposing gap between them for electrical insulation therebetween. There is a mode that there is.

With this configuration, the space occupied by both bus bars can be reduced while ensuring electrical insulation between the pair of bus bars, and the height of both bus bars can be reduced to further reduce the size and weight of the case mold type capacitor. Inductance can be achieved.

The present invention can also include a configuration in which an insulating material is not interposed between a pair of busbars.

According to the present invention, the filling resin leaking from the facing gap between the upper end face of the case side wall plate and the bus bar and flowing down the outer side face of the case side wall plate is reliably received by the resin reservoir, so that the exterior An exterior case that prevents the filling resin from adhering to and solidifying on jigs near the outside of the case, while miniaturization and low inductance can be achieved by reducing the height, and at the same time, no sink or void occurs Injection molding and prevention of insufficient strength of the molding die can be realized.

1 is a perspective view of a case mold type capacitor in an embodiment of the present invention (see-through state of mold resin); FIG. 1 is a plan view of a case mold type capacitor in an embodiment of the present invention; FIG. FIG. 1 is a longitudinal side view of a case mold type capacitor in an embodiment of the present invention; 1 is an exploded perspective view of a case mold type capacitor in an embodiment of the present invention; FIG. 1 is a perspective view (external view) of a case mold type capacitor in an embodiment of the present invention; FIG. FIG. 4 is a perspective view (outside view) of a case mold type capacitor in another embodiment of the present invention; FIG. 10 is a perspective view (external view) of a case mold type capacitor according to still another embodiment of the present invention;

Embodiments of the case mold type capacitor of the present invention having the above configuration will be described below in detail at the level of specific examples. First, a basic embodiment will be described with reference to FIGS. 1 to 5. FIG.

In the figure, 1 is a capacitor element, 2 is a first bus bar, 3 is a second bus bar, 4 is a sheet-like insulating material, 5 is a main part of the capacitor, 6 is an exterior case, and 7 is a molding (filling) resin. . A plurality of capacitor elements 1 , a pair of busbars 2 and 3 and an insulating material 4 constitute a capacitor main portion 5 . The rising plate portions 2b and 3b and the external connection terminal portions 2c and 3c of the pair of busbars 2 and 3 are arranged in parallel and opposed to each other in close proximity to each other. An insulating material 4 is inserted and interposed for physical insulation.

Capacitor element 1 is placed so that its axial direction is the vertical direction. One end of the first bus bar 2 is connected to an electrode (one electrode, for example, a P pole (anode)) 1a on the axial lower end surface of the capacitor element 1, and an electrode (the other electrode, for example, an axial upper end surface) 1a on the axial lower end surface of the capacitor element 1 One end of the second bus bar 3 is connected to the N pole (cathode) 1b. Each of the pair of busbars 2 and 3 is made entirely of a sheet of conductive metal such as a copper plate, and is bent into a generally crank shape. It has external connection terminal portions 2c and 3c at the bottom and raised plate portions 2b and 3b between the base portions 2a and 3a and the external connection terminal portions 2c and 3c.

Each of the rising plate portions 2b and 3b is bent substantially perpendicular to the base portions 2a and 3a, and each of the external connection terminal portions 2c and 3c is bent substantially perpendicular to the rising plate portions 2b and 3b. . Narrow fastening tongue portions 2c ₁ and _{3c 1} protrude from the distal end portions of the external connection terminal portions 2c and _3c . Holes 2d and 3d are formed.

The horizontal base portion 2a of the first bus bar 2 is overlapped with the electrode 1a on the lower surface side of the capacitor element 1, and the base portion 3a of the second bus bar 3 is overlapped with the electrode 1b on the upper surface side of the capacitor element 1. The connecting projections integrally projected from the bases 2a and 3a are electrically and mechanically connected to the electrodes 1a and 1b by soldering.

The insulating material 4 has a vertical plate portion 4a and a horizontal plate portion 4b, which are formed by bending a single plate into an L shape, for example. The rising plate portion 2b of the first busbar 2 and the rising plate portion 3b of the second busbar 3 are arranged close to each other so as to face each other in a vertical posture parallel to each other. A vertical plate portion 4a of the insulating material 4 is inserted and interposed therebetween. The wide base portion of the external connection terminal portion 2c of the first bus bar 2 and the wide base portion of the external connection terminal portion 3c of the second bus bar 3 are arranged close to each other so as to face each other in a parallel horizontal posture. A horizontal plate portion 4b of the insulating material 4 is interposed between the pair of wide base portions. The insulating material 4 extends to both sides of the pair of busbars 2 and 3, including the entire width range of the overlapping regions of the rising plate portions 2b and 3b and the external connection terminal portions 2c and 3c facing each other. are arranged (this state appears in FIG. 2 (plan view)).

The small-width fastening tongue portion 2c ₁ of the external connection terminal portion 2c is arranged at one side end, and the narrow fastening tongue portion 3c ₁ of the external connection terminal portion 3c is arranged at the other side end portion. are placed side by side. The fastening tongue portion 2c ₁ and the fastening tongue portion 3c ₁ do not overlap, and the horizontal plate portion 4b of the insulating material 4 is not interposed between these portions.

A plate-like member made of resin is used as the insulating material 4, but a sheet-like insulating member such as insulating paper may be used instead of the plate-like insulating member. Optional. As the insulating material 4, for example, PPS (polyphenylene sulfide) is used.

The exterior case 6 has a rectangular parallelepiped shape, has an upward opening 6a, and is made of resin. The exterior case 6 has a case bottom plate portion 6b and four case side wall plates 6c, and the resin reservoir portion 6d is connected to the outer side surface 6c ₂ of one case side wall plate 6c.

Inside the exterior case 6, the capacitor element 1 in the main part 5 of the capacitor, one end side of the pair of bus bars 2 and 3 (the entire base part and part of the rising plate part excluding the external connection terminal part), and the insulating material 4 are placed. A part of the vertical plate portion 4a is accommodated and fixed with a molding resin 7 such as an epoxy resin. The mold resin 7 is filled up to a position slightly lower than the height position of the opening 6a of the exterior case 6. As shown in FIG. In fixing the capacitor element 1 and the bus bars 2 and 3, the attitude of the capacitor element 1 is performed in a state in which predetermined parallelism and orthogonality are secured with respect to the outer case 6 as shown in the drawing.

The horizontal external connection terminal portions 2c and 3c, which are the free ends of the pair of bus bars 2 and 3, extend outside the case side wall plate 6c of the exterior case 6. As shown in FIG.

Of the pair of busbars 2 and 3, the first busbar 2, which is lower than the pair of busbars 2 and 3, has a vertical upright plate portion 2b that follows the inner surface 6c1 of the side wall plate 6c of the exterior case ₆ with a small gap therebetween. It's becoming These minute gaps are the cause of capillarity with respect to the filling resin. The horizontal external connection terminal portion 2c, which is formed by further horizontally bending the upper end portion of the rising plate portion 2b, is positioned along the upper end surface _6c3 of the case side wall plate 6c with a small gap therebetween. This minute gap also causes capillary action to reach the exit.

The vertically-positioned rising plate portion 2b of the lower first bus bar 2 is arranged along the inner surface _6c1 of the case side wall plate 6c with a vertical minute gap therebetween. When the liquid filling resin, which is the source of the resin 7, is injected and filled into the exterior case 6 through the opening 6a thereof, part of the filling resin is sucked up by capillary action in the minute gaps extending in the vertical direction. Furthermore, since the external connection terminal portion 2c in a horizontal posture is arranged along the upper end surface 6c3 of the case side wall plate _6c through a minute gap extending in the horizontal direction, the above-mentioned capillary action sucks up the external connection terminal portion 2c. The filling resin is further sucked out in the horizontal direction by capillary action in the minute gaps extending in the vertical direction. From the position where the minute gap extending in the horizontal direction is interrupted, that is, the position corresponding to the outer surface 6c ₂ of the case side wall plate 6c (the exit position where the capillary action is also interrupted), the filling resin leaking out is pushed by the gravity of the case side wall plate 6c. flows down along the outer surface 6c ₂ of .

Thus, the capillary phenomenon is interrupted, and the filled resin that flows down due to gravity is received and stored by the resin reservoir 6d connected to the outer surface 6c ₂ of the case side wall plate 6c.

The resin reservoir portion 6d is provided in a posture facing further outward than the outer surface 6c2 of the case side wall plate 6c, and the first bus bar ₂ faces the upper end surface _6c1 of the case side wall plate 6c. The resin reservoir 6d extends in the horizontal direction corresponding to the region. The configuration of the resin reservoir 6d will be specifically described below.

The resin reservoir portion 6d is composed of a plate-like body having a substantially constant thickness. The horizontal width of the plate-like body is set to a width sufficient to cover the horizontal region where the overflowing filling resin may flow down due to gravity. In this embodiment, resin reservoirs 6d are arranged so as to extend over horizontal ranges each extending a predetermined dimension from the full width range of the wide base portion of the external connection terminal portion 2c of the lower first bus bar 2 to both outer sides thereof. .

The plate-shaped body that constitutes the resin reservoir 6d is configured such that its tip (free end) is located at a higher position than the root (base end) to the case side wall plate 6c. That is, it has a flat plate-like body that is tilted at an appropriate elevation angle (the angle formed by the horizontal line and the line of sight from the bottom to the top) with the base part being the lower part and the tip part being the upper part, and the horizontal direction of the plate-like body Shearing plates 6d ₁ , 6d ₁ for preventing flow down are connected to both ends.

In this embodiment, the longitudinal cross-sectional shape of the resin reservoir 6d is a linear flat plate extending obliquely upward. It may have a cross-sectional shape such as For example, even if it is an L-shaped cross-sectional shape that extends horizontally outward from the root and further extends vertically upward, or a cross-sectional shape that extends horizontally outward from the root. good. The resin reservoir 6d merely receives the filled resin that has crawled up due to capillary action and drips down from the exit of the minute gap due to gravity. It is not like introducing a filling resin.

The connection position of the resin reservoir 6d on the case side wall plate 6c is set at a position immediately below the upper end surface _6c3 of the case side wall plate 6c. As shown in FIG. 6, the connecting position of the resin reservoir 6d on the case side wall plate 6c may be set substantially in the middle of the vertical width of the case side wall plate 6c. Alternatively, the resin reservoir 6d may be connected to the case side wall plate 6c at a position near the lower end of the case side wall plate 6c as shown in FIG.

In the above-described embodiment, the outer case 6 is made of a resin molded body, and the resin reservoir 6d is also made of the same resin molded body. As a modification, the resin reservoir 6d may be provided separately from the exterior case 6, and the resin reservoir 6d may be attached to the exterior case 6. FIG. Adhesion, screwing, spot welding, or the like may be used as the attachment means. Further, the material of the exterior case 6 (case side wall plate 6c) and the material of the resin reservoir 6d are not limited to the same type of synthetic resin, but a combination of different types of synthetic resin, a combination of synthetic resin and metal. The combination is arbitrary, such as a combination (which may be synthetic resin and which may be metal).

In the above-described embodiment, the number of capacitor elements 1 in the capacitor main portion 5 is two, but the number may be any number of two or more, or may be singular. In the above-described embodiment, the rising plate portion 2b of the lower first busbar 2 of the pair of busbars 2 and 3 is configured to run along the inner surface _6c1 of the case side wall plate 6c with a minute gap therebetween. However, instead of this, the raised plate portion 3b of the upper second bus bar 3 may be configured to follow the inner surface _6c1 of the case side wall plate 6c with a minute gap therebetween, or Both of the rising plate portions 2b and 3b may be arranged along the inner surface _6c1 of the side wall plate 6c of the case with a small gap therebetween. Note that the insulating material 4 may be omitted.

The present invention relates to a case mold type capacitor. Filling resin leaks out due to capillary action caused by a minute gap between the side wall plate of the case and the bus bar, and flows down due to gravity. It is useful as a technique for avoiding inconveniences and realizing miniaturization and low inductance by reducing the height.

Reference Signs List 1 capacitor element 1a, 1b electrode 2 first busbar 3 second busbar 4 insulating material 5 main part of capacitor 6 outer case 6a opening 6c case side wall plate 6c ₁ inner surface 6c ₂ outer surface 6c ₃ upper end surface 6d resin reservoir 7 Mold (filling) resin

Claims (5)

A main part of a capacitor formed by connecting a pair of busbars to metal electrodes at both ends of a capacitor element is housed in an exterior case having an opening, and the base sides of the capacitor element and the pair of busbars are filled in the exterior case. a case mold type capacitor in which the free end sides of the pair of bus bars extend outside the exterior case,
the capacitor element is arranged such that one of the metal electrodes at both ends faces the bottom surface of the exterior case and the other metal electrode faces the opening of the exterior case;
One of the pair of bus bars is connected to the one metal electrode of the capacitor element, extends along the inner surface of the case side wall plate of the outer case, and bends to the upper end surface of the case side wall plate. extending out of the exterior case along the
The other bus bar of the pair of bus bars is connected to the other metal electrode of the metal electrodes at both ends of the capacitor element, and faces the one bus bar via an insulating material and is disposed outside the exterior case. further bent to extend out of the outer case with the insulating material and the one bus bar interposed between the upper end surface of the case side wall plate,
an upper end surface of the side wall plate of the case is flat and faces the one bus bar with a first minute gap therebetween;
the one bus bar faces the inner surface of the case side wall plate with a second minute gap therebetween,
The first and second minute gaps form a continuous gap that causes a capillary phenomenon with respect to the filling resin in the exterior case,
It is sucked up by capillary action in the second minute gap, then sucked out of the exterior case by capillary action in the first minute gap, and the first air is sucked out of the exterior case at a position corresponding to the outer surface of the side wall plate of the case. A case mold type characterized in that a resin reservoir for receiving filling resin that leaks and flows down from a minute gap is provided on the case side wall plate in a posture facing outward from the outer surface of the case side wall plate. capacitor. 2. The resin reservoir according to claim 1, wherein the resin reservoir is formed so as to extend in the horizontal direction corresponding to a region where the one bus bar faces the upper end surface of the side wall plate of the case. Case mold type capacitor. 3. A case mold type capacitor according to claim 1, wherein said exterior case is a molded resin body, and said resin reservoir is formed integrally with said side wall plate of said case by the same molded resin body. . 4. The resin reservoir according to any one of claims 1 to 3, wherein the resin reservoir is formed of a plate-like body, and the tip of the plate-like body is located at a position higher than the root portion to the side wall plate of the case. Case mold type capacitor as described. 5. The case mold type capacitor according to any one of claims 1 to 4, wherein the resin reservoir is provided on an upper end side including a position near the lower end surface of the upper end surface of the case side wall plate.

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