JPS6234125B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an exterior packaging method for an electrolytic capacitor,
In particular, the present invention relates to an improvement in a method of sealing an exterior case made of synthetic resin. The exterior case that encloses the electrolytic capacitor element is made of a material that does not deteriorate the electrode foil and electrolyte, which not only prevents leakage of the electrolyte but also prevents internal pressure from rising due to gas generated during normal use. There is a need to use a sealing method that is durable, prevents gas leakage, and maintains constant electrical characteristics of the device. Therefore, when this exterior case is made of synthetic resin, a limited number of synthetic resins are used, such as polypropylene and polyphenylene oxide, in consideration of the effect on the electrode foil and electrolyte, and the sealing method is Ultrasonic welding is used. Generally, when welding synthetic resin pieces using ultrasonic heating, in order to obtain a sufficient fusion state at the joint, a pocket is formed in one of the synthetic resin pieces between the joints, and the weld is inserted into this pocket. A method is adopted in which the protrusion is formed on the other synthetic resin piece, and the two pieces are heated and welded while maintaining the fitted state. However, setting the shape of the joint in this way is effective when the area of the synthetic resin joint is large or the strength of the synthetic resin at the joint is high, but it is effective when setting the joint shape in this way. If the wall thickness of the exterior case cannot be made sufficiently due to demands such as environmental protection, the strength of the vertical wall that forms the pocket will be reduced, and cracks will occur due to the pressure applied during ultrasonic welding. The fusion state at the welded part becomes insufficient. For this reason, welding control such as the application of ultrasonic waves and pressurization becomes very complicated, which causes a decrease in work efficiency and a deterioration in yield. Furthermore, in order to increase the strength of the synthetic resin piece and prevent the pocket portion from breaking, a method has been proposed in which the synthetic resin piece contains a filler. However, although the inclusion of filler is effective in increasing the strength, it also causes a decrease in weldability, which may result in insufficient sealing. This invention was proposed based on the knowledge that the difference in filler content between synthetic resin materials to be welded changes the strength and weldability of the welded part, and maintains the strength and weldability of the welded part. The present invention aims to provide an exterior packaging method for an electrolytic capacitor that ensures sufficient airtightness and facilitates welding work. In the present invention, one of the outer case pieces in which a pocket portion is formed at the joint portion is made of a synthetic resin containing filler, and the other outer case piece in which a protrusion to be inserted into the pocket portion is formed is made of a synthetic resin containing a filler. It is characterized in that it is formed from a synthetic resin containing a filler at a ratio lower than the content ratio or containing no filler at all. Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a part of the exterior case with an electrolytic capacitor element mounted thereon before being sealed. In the figure,
Exterior case 4 enclosing electrolytic capacitor element 2
is composed of an exterior case piece 6 in the shape of a square cylinder with a bottom and a storage space formed therein, and a flat exterior case piece 8 for a lid that closes the opening of this exterior case piece 6. The joining surfaces of these exterior case pieces 6 and 8 by ultrasonic welding are the end face at the opening of the exterior case piece 6 and the exterior case piece 8 corresponding to this end face.
It is formed on the entire edge of. A pocket portion 12 consisting of a groove portion surrounded by vertical walls 10A and 10B is formed on the joint surface of the outer case piece 6 over the entire circumference. On the other hand, a protrusion 14 to be inserted into the pocket part 12 is formed on the joint surface of the outer case piece 8 all around the circumference, and the protrusion 14 has a tapered surface on both sides, leaving a narrow flat surface at the tip. It is formed into a sharp knife edge shape. Each of the outer case pieces 6 and 8 thus formed are both molded from a synthetic resin such as polypropylene or polyphenylene oxide, and the outer case piece 6 is made of a certain amount of, for example, 10% by weight in order to increase its strength. The outer case piece 8 for the lid is made of a synthetic resin containing about 30% filler, while the outer case piece 8 for the lid is made of a synthetic resin containing filler at a lower content ratio than the above-mentioned content ratio, for example, 0 to 5% filler by weight. ing. That is, the synthetic resin forming the outer case piece 8 does not contain filler at all or contains filler in a smaller proportion than the outer case piece 6, so it has higher weldability than the outer case piece 6. Further, in the case of this embodiment, a plate-shaped terminal 16 is embedded in the outer case piece 8, and the electrolytic capacitor element 2 is held between the plate-shaped terminals 16 on the anode side and the cathode side. A tab 20 fixed to the inner surface and pulled out from the end surface of the electrolytic capacitor element 2 is connected to the connecting portion 2 of the plate terminal 16.
It is electrically connected to 2. In addition, the plate terminal 1
An external connection terminal 24 made of a solderable wire is fixed to the embedded portion 6 , and this terminal 24 protrudes from the upper surface of the outer case piece 6 . That is, a portion of the plate terminal 16 is embedded inside the outer case piece 6 at the same time as it is formed, and the connection of the tab 20 and the fixing of the electrolytic capacitor element 2 are performed before the outer case 4 is sealed. . In the above configuration, the electrolytic capacitor element 2 to which the lid-forming exterior case piece 8 is fixed to the upper part of the exterior case piece 6 is maintained facing inside the storage space of the exterior case piece 6, and then The protrusion 14 of the outer case piece 8 is inserted into the inside of the pocket portion 12. In this state, ultrasonic waves are applied between the outer case pieces 6 and 8 while applying pressure in the directions of arrows A and B.
As a result, the protrusion 14 is melted inside the pocket portion 12, and together with the melting of the inner surface of the pocket portion 12, the joint surfaces of the outer case pieces 6 and 8 are fused, integrated, and welded. In this case, since the synthetic resin forming the exterior case piece 6 contains filler, the vertical wall 10 forming the pocket portion 12
A and 10B have sufficient strength for pressure welding when applying ultrasonic waves. In addition, since the synthetic resin forming the outer case piece 8 does not contain filler at all or contains less filler than the filler, the synthetic resin in the protrusion 14 and its vicinity does not have sufficient weldability. There is. Since the content of filler in the synthetic resin between the joint surfaces differs in this way, sufficient strength and weldability are ensured, and a high degree of airtightness is achieved through a good fusion state.
Welding work becomes easier, and it is possible to improve work efficiency and yield. Next, experimental results of this invention will be explained.
A rectangular parallelepiped-shaped exterior case was used for the experiment, and the exterior shape of the exterior case piece 6 constituting the container part was 50.5 mm in length.
mm, width 35.5 mm, height 16.9 mm bottomed square cylinder, external shape of lid exterior case piece 8 is length 50.5 mm, width 35.5 mm
mm, and a rectangular shape with a thickness of 3.2 mm. The cross-sectional shape of the joint surface of each outer case piece 6, 8 is constructed as shown in FIGS. 2A and B, and its dimensions are a=3.2
mm, b=1.5mm, c=1.0mm, d=0.5mm, e=0.2
mm, f=0.8mm, g=2.5mm, h=0.7mm, i=1.1
mm, j=1.0 mm. In the experiment, polypropylene and polyphenylene oxide were used as synthetic resins to form the outer case pieces 6 and 8 having such shapes, and each synthetic resin and each outer case piece 6 and 8 were tested using polypropylene and polyphenylene oxide.
For 8, the glass content is 0, 10, 30 in weight ratio
%, an outer case 4 is formed, and inside it contains approximately the same amount of electrolyte as the electrolyte that is impregnated into the electrolytic capacitor element, and is left in an atmosphere at 105°C for 45 hours, followed by electrolysis. The state of liquid leakage was measured by the change in weight, and the presence or absence of liquid leakage was visually observed. In this case, those that were clearly found to have leaked by visual observation and those whose weight changed by 99% or less were considered defective. The results of this experiment are shown in Table 1.

[Table] As is clear from the results of this experiment, the synthetic resin constituting the outer case piece 6 contains a filler,
It can be seen that good airtightness can be obtained when the synthetic resin constituting the other exterior case piece 8 does not contain filler at all or contains filler in a low proportion. In addition, as another experiment, we enclosed an electrolytic capacitor element in the outer case containing filler at the ratio that yielded good results in the above experiment, and measured its life characteristics after applying voltage for 2000 hours at 105°C. did.
In other words, changes in capacitance, tan δ, leakage current, and weight changes are measured as electrical characteristics, and a large change in any one of them is determined based on the JIS (Japanese Industrial Standards) criteria. was considered to have poor characteristics. The results are shown in Table 2. As is clear from the results of this experiment, the same results as in the previous experiment were obtained regarding the occurrence of characteristic defects. Note that, like the previous experiment, this experiment included a case in which the content of filler in the synthetic resin constituting the outer case piece was the same for comparison.

[Table] As explained above, according to the present invention, the strength and weldability of the welded part can be maintained well, sufficient airtightness can be obtained, and the welding work can be made easier.
It is possible to improve efficiency and yield.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a part of an electrolytic capacitor in which the electrolytic capacitor packaging method of the present invention is implemented;
FIGS. 2A and 2B are cross-sectional views showing the structure of the joint. 2... Electrolytic capacitor element, 4... Exterior case, 6, 8... Exterior case piece.

Claims (1)

[Claims] 1. An electrolytic capacitor element is stored in a storage space formed in at least one of the outer case pieces, and this outer case piece and the other outer case piece that seals the storage space are bonded, and the bonded portion is heated using ultrasonic waves. In an exterior packaging method for an electrolytic capacitor that is sealed by welding, one exterior case piece in which a pocket part is formed at the joint part is formed of a synthetic resin containing a filler, and a protrusion to be inserted into the pocket part is formed. 1. A method for packaging an electrolytic capacitor, characterized in that the other packaging case piece is made of a synthetic resin containing a filler at a lower content ratio than the above-mentioned content ratio or containing no filler at all.