JP4765343B2 - Case mold type capacitor - Google Patents

Description

  The present invention relates to a case mold type capacitor that is used as a smoothing capacitor for an in-vehicle motor-driven inverter circuit among case mold type capacitors in which a capacitor element is resin-molded in a case.

  In recent years, metallized film capacitors used for inverter devices have been actively developed for downsizing, high performance, and low cost. In addition, since metallized film capacitors used in inverter devices are required to have a high operating voltage, large current, large capacity, etc., a plurality of capacitor elements connected in parallel are accommodated in a case. A case mold type metallized film capacitor in which a resin is cast in a case has been developed and put into practical use.

  And in such a case mold type metallized film capacitor, those having excellent mechanical strength, high heat resistance temperature, water resistance and oil resistance have been pursued.

  FIG. 9 is an exploded perspective view showing the structure of this type of conventional case mold type capacitor, FIG. 10 is a cross-sectional view taken along the line A-A in FIG. 9 and FIG. Capacitor element 10 is formed by winding a metallized film having metal vapor-deposited electrodes on one or both sides so that a pair of metal vapor-deposited electrodes face each other with a dielectric film therebetween, and electrodes are provided on both end surfaces. is there.

  Reference numeral 11 denotes a first electrode bus bar, 11a denotes a first electrode terminal for external connection provided at one end of the first electrode bus bar 11, and the first electrode bus bar 11 includes a plurality of the capacitor elements 10. In a state of being in close contact with each other, the first electrode formed on one end face of each capacitor element 10 is joined, and the first electrode terminal 11a is pulled out above the capacitor element 10 to be described later. It is made to express from 13.

  Reference numeral 12 denotes a second electrode bus bar, 12a denotes a second electrode terminal for external connection provided at one end of the second electrode bus bar 12, and the second electrode bus bar 12 is also the first electrode bus bar 11 described above. Similarly, a plurality of capacitor elements 10 are arranged in close contact with each other and bonded to a second electrode formed on one end face of each capacitor element 10, and the second electrode terminal 12a is connected to this capacitor element. It is pulled out above the element 10 and exposed from a case 13 to be described later, whereby a plurality of capacitor elements 10 are connected.

  13 is a case made of polyphenylene sulfide (hereinafter referred to as PPS) resin, 14 is a mold resin filled in the case 13, and the mold resin 14 is formed by the first electrode bus bar 11 and the second electrode bus bar 12. A plurality of connected capacitor elements 10 are resin-molded in a case 13, and this case 13 is housed in an outer case 15.

  The conventional case mold type capacitor configured as described above is obtained by molding the capacitor element 10 in the case 13 with the mold resin 14 having excellent heat resistance, moisture resistance, and insulation resistance. By using PPS which is excellent in mechanical strength, heat resistance and water resistance and can withstand harsh use conditions, it is possible to provide a case mold type capacitor with higher reliability than before.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2004-146724 A

  However, in the conventional case mold type capacitor, the capacitor element 10 is molded in the case 13 made of PPS by using the mold resin 14 to ensure higher reliability than the conventional case. In applications, the required conditions were severe, and there was a problem that further moisture resistance and mechanical strength were required.

  Therefore, a method of using a metal case is conceivable as a means for solving such a problem and particularly improving the moisture resistance, but in a conventional case mold type capacitor, the case 13 can be used. Synthetic resin is generally used as the material, and this is due to the difference in the linear expansion coefficient between the molding resin 14 and the case 13 material, and the molding resin generated in the thermal shock test or the like due to the lack of adhesive strength between the two. 14 for the purpose of preventing the occurrence of peeling and cracking of 14 and it was extremely difficult to use a metal case for this reason, and had the problem of having to give up. .

  An object of the present invention is to solve such a conventional problem, and to provide a case mold type capacitor capable of exhibiting extremely high moisture resistance performance by resin molding a capacitor element in a metal case. It is.

In order to solve the above problems, the present invention provides a resin mold in which a bus bar provided with a terminal portion for external connection is connected to an electrode portion of a capacitor element, which is accommodated in a case and at least the terminal portion of the bus bar is removed. In the case mold type capacitor, an epoxy resin containing 63 to 68 wt% inorganic filler and 1 to 10% round filler in the inorganic filler is used as the mold resin used for the resin mold. The case uses a metal case mainly made of aluminum.

  As described above, the case mold type capacitor according to the present invention uses a metal case mainly made of aluminum for the case, so that the moisture resistance is drastically improved. Furthermore, the mold resin has excellent adhesive strength with the metal case. By using, the wettability with the case is greatly improved and the adhesive strength is improved, so there is no mold resin peeling or cracking even in the thermal shock test, not only moisture resistance but also high reliability The effect that it can do is acquired.

(Embodiment 1)
Hereinafter, the invention described in the first to fourth aspects of the present invention will be described using the first embodiment.

  FIG. 1 is an exploded perspective view showing the configuration of a case mold type capacitor according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1 and FIG. The capacitor element 1 is formed by winding a metallized film having a metal vapor deposition electrode on one or both sides so that a pair of metal vapor deposition electrodes face each other with a dielectric film therebetween, and providing electrodes on both end surfaces. Is.

  Reference numeral 2 denotes a first electrode bus bar made of a copper plate, 2a denotes a first electrode terminal for external connection provided at one end of the first electrode bus bar 2, and the first electrode bus bar 2 is the capacitor element 1 In a state where a plurality of electrodes are arranged in close contact with each other, they are joined to a first electrode formed on one end face of each capacitor element 1, and the first electrode terminal 2 a is pulled out above the capacitor element 1. The metal case 4 is exposed.

  Reference numeral 3 denotes a second electrode bus bar made of a copper plate, 3a denotes a second electrode terminal for external connection provided at one end of the second electrode bus bar 3, and the second electrode bus bar 3 is also the first electrode bus bar. Similarly to the electrode bus bar 2, a plurality of the capacitor elements 1 are in close contact with each other and bonded to the second electrode formed on the other end face of each capacitor element 1, and the second electrode terminal 3a is The capacitor element 1 is drawn upward and exposed from a metal case 4 described later, whereby a plurality of capacitor elements 1 are connected.

  4 is a metal case made of aluminum, and 5 is an insulating sheet formed using a polypropylene film (thickness: 200 μm). The insulating sheet 5 is disposed on the inner surface of the metal case 4 so that the metal case 4 And the capacitor element 1 and the first electrode bus bar 2 or the second electrode bus bar 3 bonded thereto are prevented from being short-circuited.

  6 is a mold resin filled in the metal case 4, and the mold resin 6 connects a plurality of capacitor elements 1 connected by the first electrode bus bar 2 and the second electrode bus bar 3 to the first electrode. The metal case 4 is resin-molded except for a part of the terminal 2a and the second electrode terminal 3a.

  Further, as shown in detail in (Table 1), this mold resin 6 contains an epoxy resin as a main material, contains 68 wt% of an inorganic filler, and 10% of a round filler in the inorganic filler. It has a linear expansion coefficient of 25 ppm / ° C., a cure shrinkage ratio of 0.96%, and an adhesive strength with aluminum constituting the metal case 4 of 3 MPa. It can be seen that the linear expansion coefficient and cure shrinkage ratio are greatly reduced compared to the mold resin used in the conventional product, and the adhesive strength with aluminum as the material constituting the metal case 4 is also high. It can be seen that

  In addition, in order to confirm the moisture resistance performance of the case mold type capacitor according to the present embodiment configured as described above, a conventional product as a comparative example is a result of performing a moisture resistance current test by applying a DC 500 V current at 90 ° C. and 85%. FIG. 3 shows a comparison with (using a case made of PPS resin).

  As apparent from FIG. 3, the case mold type capacitor according to the present embodiment is excellent in moisture resistance due to the configuration using the metal case 4 and the mold resin 6 that is familiar to the metal case 4. In the present embodiment, the capacity decrease reaches 5% in about 2300 hours, whereas in this embodiment, there is no tendency for capacity decrease even after nearly 2700 hours have passed. It can be seen that it exhibits high moisture resistance.

  Further, as a result of conducting a thermal shock test in which the case mold type capacitor according to the present embodiment is held at −40 ° C. and 90 ° C. for 2 hours each and this is repeated as one cycle, the mold resin is used even after 500 cycles. No peeling or cracking of 6 occurs, and it can be seen that the conventional product exhibits excellent effects against the peeling and cracking of the mold resin in one cycle.

  4 and 5 are characteristic diagrams showing changes in linear expansion coefficient and curing shrinkage when the content of the inorganic filler contained in the epoxy resin constituting the mold resin 6 is changed. Table 2 shows the results of a thermal shock test of a case mold type capacitor produced using the above mold resin (held at -40 ° C and 90 ° C for 2 hours each and repeating this as one cycle).

  As is clear from Table 2, the conventional product having an inorganic filler content of 53 wt% with respect to the epoxy resin peels off between the aluminum case and the mold resin in one cycle of thermal shock, and the first and second While cracks are generated in the vicinity of the electrode terminals and the performance is affected, those having an inorganic filler content of 63 to 80 wt% with respect to the epoxy resin according to the present embodiment show good results, particularly inorganic fillers Since the content of 68 to 75 wt% of the resin shows the best results, the content of the inorganic filler with respect to the epoxy resin is preferably 63 to 80 wt%, more preferably 68 to 75 wt%. I understand.

  Similarly, it is understood that the linear expansion coefficient is 30 to 14 ppm / ° C. and the curing shrinkage is 1.1 to 0.62% when the content of the inorganic filler with respect to the epoxy resin is 63 to 80 wt%.

  FIG. 6 is a characteristic diagram showing the viscosity change of the mold resin when the content of the round filler contained in the inorganic filler is changed when the content of the inorganic filler with respect to the epoxy resin is 68 wt%. Table 3 shows the workability and surface finish of the mold resin.

  As is clear from Table 3, it can be seen that the inclusion of 1% or more of the round filler in the inorganic filler contained in the epoxy resin drastically reduces the viscosity of the mold resin. It can be seen that the mold resin spreads to every corner and the workability is improved, and the content of this round filler is preferably 10%, so that a greater effect can be obtained. I understand.

  Moreover, (Table 4) and (Table 5) were produced using what set the adhesive strength with aluminum of the mold resin which changed content of the inorganic filler with respect to the said epoxy resin to 3 MPa, and the same 4 MPa. The thermal shock test result of a case mold type capacitor is shown.

  As is clear from (Table 4) and (Table 5), the adhesive strength of the mold resin to aluminum is exactly the same as that of 3 MPa and 4 MPa. From this, the adhesive strength of the mold resin to aluminum is It can be seen that there is no problem if is 3 MPa or more.

  As described above, the case mold type capacitor according to the present embodiment uses the metal case 4 as a case for housing the capacitor element 1 and has a configuration using the mold resin 6 that is familiar with the metal case, so that the mold resin 6 The linear expansion coefficient and cure shrinkage of the resin can be greatly reduced, and extremely high moisture resistance can be exhibited.

(Embodiment 2)
Hereinafter, the invention according to claim 5 of the present invention will be described using the second embodiment.

  In this embodiment, the configuration of the mold resin of the case mold type capacitor described in the first embodiment is partially different, and the other configurations are the same as those in the first embodiment, and thus the same. The same reference numerals are given to the portions, and detailed description thereof is omitted, and only different portions will be described below with reference to the drawings.

  FIG. 7 is an exploded perspective view showing the configuration of the case mold type capacitor according to the second embodiment of the present invention, FIG. 8 is a cross-sectional view taken along the line AA of FIG. 7, and FIG. 7 and FIG. The mold resin used in the case mold type capacitor is shown. The mold resin 7 includes a plurality of capacitor elements 1 housed in a metal case 4, and a first electrode bus bar 2 and a second electrode bus bar 2 connected thereto. It is only cast to the position where the electrode bus bar 3 is covered.

  The mold resin 6 used in the case mold type capacitor described in the first embodiment is cast from the upper part of the mold resin 7 to the upper end of the opening of the metal case 4. The structure is cast in a layer structure.

  The case mold type capacitor according to the present embodiment configured as described above has the metal case 4 even if the lower layer portion of the mold resin cast in the metal case 4 is a general epoxy mold resin 7. The structure using the mold resin 6 that is well-familiar with the metal case 4 in the upper layer portion serving as the opening greatly improves the wettability with the metal case 4 and improves the adhesive strength. Therefore, the mold resin is also used in the thermal shock test. No peeling or cracking of 6 occurs, and the effect that not only moisture resistance but also high reliability can be exhibited as in the first embodiment is obtained.

  Further, the mold resin 7 has a low viscosity because it contains less inorganic filler than the mold resin 6, and therefore, the workability is excellent because the casting time into the metal case 4 can be shortened. It is effective.

  In addition, in order to confirm the moisture resistance of the case mold type capacitor according to the present embodiment configured as described above, a conventional product as a comparative example is a result of performing a moisture resistance current test by applying DC 500V at 90 ° C. and 85%. FIG. 3 shows a comparison with (using a case made of PPS resin).

  As is apparent from FIG. 3, the case mold type capacitor according to the present embodiment uses a metal case 4 and has a structure in which a mold resin 6 that is familiar with the metal case 4 is cast in the upper layer portion, thereby providing moisture resistance. In the present embodiment, the capacity decrease reaches 5% in about 2300 hours, whereas in this embodiment, the capacity decrease tends to be observed even after nearly 2700 hours. It can be seen that it exhibits extremely high moisture resistance.

  Further, the case mold type capacitor according to the present embodiment was held at −40 ° C. and 90 ° C. for 2 hours each, and a thermal shock test was repeated as one cycle. As a result, the same as in the first embodiment. It can be seen that even after 500 cycles, the mold resin 6 is not peeled off and cracks are generated, and an excellent effect is exhibited.

  The case mold type capacitor according to the present invention has an effect of exhibiting extremely high moisture resistance, and is particularly useful as an in-vehicle field where high reliability is required.

1 is an exploded perspective view showing the configuration of a case mold type capacitor according to Embodiment 1 of the present invention. AA sectional view Characteristic diagram showing the capacitance change rate Characteristic diagram showing the change of linear expansion coefficient when the content of inorganic filler contained in the epoxy resin is changed Characteristic diagram showing the change in cure shrinkage when the content of inorganic filler contained in the epoxy resin is changed Characteristic diagram showing the viscosity change of the mold resin when the content of the round filler contained in the inorganic filler is changed The disassembled perspective view which showed the structure of the case mold type capacitor | condenser by Embodiment 2 of this invention AA sectional view An exploded perspective view showing a configuration of a conventional case mold type capacitor AA sectional view

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 1st electrode bus bar 2a 1st electrode terminal 3 2nd electrode bus bar 3a 2nd electrode terminal 4 Metal case 5 Insulating sheet 6, 7 Mold resin

Claims (5)

In a case mold type capacitor in which a bus bar provided with a terminal portion for external connection is connected to an electrode portion of a capacitor element, and this is accommodated in a case and resin-molded by removing at least the terminal portion of the bus bar, the resin mold As a mold resin to be used, an epoxy resin containing 63 to 68 wt% of an inorganic filler and 1 to 10% of a round filler in the inorganic filler is used, and a metal case mainly composed of aluminum is used for the case. Case mold type capacitor used. The case mold type capacitor according to claim 1, wherein the linear expansion coefficient of the mold resin is 30 ppm / ° C. or less. The case mold type capacitor according to claim 1, wherein the mold resin has a curing shrinkage of 1.1% or less. The case mold type capacitor according to claim 1, wherein the adhesive strength between the mold resin and aluminum is 3 MPa or more. The mold resin to be resin-molded in the case has a two-layer structure, the lower layer contains an epoxy resin with an inorganic filler content of less than 63 wt%, the upper layer contains 63 to 68 wt% inorganic filler , and the inorganic filler is round The case mold type capacitor according to claim 1, wherein an epoxy resin containing 1 to 10% of a mold filler is used.

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