JPH0246036Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention was developed to improve electrolytic capacitors.
In particular, the present invention relates to an exterior structure of an electrolytic capacitor that can be surface mounted on a substrate without changing the structure of a conventional electrolytic capacitor.

[Conventional technology]

In recent years, with the demand for smaller and lighter electronic devices and simplified manufacturing processes, leadless electronic components that are compatible with surface mounting have been required.

Generally, an electrolytic capacitor has a structure in which a capacitor element formed by winding electrode foil is housed in a bottomed cylindrical outer case made of aluminum or the like, and the opening of the outer case is sealed with a sealing body. The lead is led from the end surface of the capacitor element, penetrates the sealing body, and projects to the outer end surface of the sealing body.

When an electrolytic capacitor of this type is easily made leadless, as shown in Japanese Patent Laid-Open No. 59-211213, one outer surface of the electrolytic capacitor where the lead is led is made of heat-resistant synthetic resin. It has been considered to arrange an insulating plate of the type shown in FIG.

[Problem that the invention attempts to solve]

However, in conventional leadless electrolytic capacitors, the thickness of the insulating plate is approximately 0.5 to 0.7 mm in order to shorten the vertical dimension of the completed product.
Therefore, heat during soldering is easily transmitted to the electrolytic capacitor body, leading to thermal deterioration of the capacitor element or electrolyte.

Additionally, soldering of electronic components is generally done using the dipping method.
Alternatively, a reflow soldering method is used, but in either method, the board is heated with electronic components mounted on the board in order to reduce the temperature difference with the solder bath or to melt the solder.

However, since conventional leadless electrolytic capacitors use a black heat-resistant synthetic resin as the insulating plate, heat from the board is easily transferred to the insulating plate.
This causes thermal deterioration of the electrolytic capacitor body, and at the same time, the temperature rise of the board itself is relatively suppressed by the amount of heat transferred to the insulating board, preventing the soldering process from speeding up.

The purpose of this invention is to provide a leadless electrolytic capacitor that suppresses the temperature rise of the electrolytic capacitor body during soldering and at the same time promotes the temperature rise of the board.

[Means to solve problems]

This idea involves attaching a seal to the opening of a bottomed cylindrical outer case that houses a capacitor element, and placing an insulating plate made of heat-resistant synthetic resin with a coloring agent on the outer surface of the seal. It is characterized by what it did. Further, the coloring agent added to the insulating plate made of the heat-resistant synthetic resin is characterized in that it is a white, red, yellow, or orange pigment or dye, or a mixture of the above-mentioned pigments or dyes.

〔Example〕

Embodiments of this invention will be described below with reference to the drawings.

FIG. 1 is a partially sectional view showing a completed state of a leadless electrolytic capacitor according to an embodiment of this invention, and FIG. 2 is a perspective view showing the external shape of an insulating plate according to an embodiment of this invention.

As shown in FIG. 1, an electrolytic capacitor is formed by housing a capacitor element 1 formed by winding an electrode foil 2 and an electrolytic paper 3 in a bottomed cylindrical exterior case 4 made of aluminum or the like. There is. A sealing body 6 made of elastic rubber or the like is arranged at the opening of the outer case 4.

The lead 5 is electrically connected to the electrode foil 2 and is welded to a terminal 9 for external connection. The terminal 9 penetrates the sealing body 6 and protrudes from the end surface of the sealing body 6 to the outside.

On the outer surface of the sealing body 6, an insulating plate 7 having a plurality of through holes 8 in the center as shown in FIG. 2 is arranged. The insulating plate 7 is made of a heat-resistant synthetic resin such as polyethylene terephthalate mixed with a white pigment, and has a white color as a whole.

The terminal 9 protruding from the outer end surface of the sealing body 6 passes through the through hole 8 provided near the center of the insulating plate 7.
It protrudes from the back surface of the insulating plate 7 and is bent along the back surface of the insulating plate 7 to form a substantially flat surface on the back surface of the insulating plate 7 .

[Effect]

As shown in FIG. 1, the leadless electrolytic capacitor obtained by this invention has terminals 9 led from capacitor element 1 that are bent along the back surface of insulating plate 7. This allows the completed electrolytic capacitor to stand on its own.

Next, temperature changes inside the electrolytic capacitor and on the surface of the board will be compared between the electrolytic capacitor according to the embodiment of this invention and a conventional leadless type electrolytic capacitor when the electrolytic capacitor is mounted on a board.

In a comparative test, we used a conventional example in which a 0.5 mm thick insulating plate made of black polyethylene terephthalate with no added colorant was placed on the end face of the electrolytic capacitor body, and a 0.5 mm thick insulating plate made of polyethylene terephthalate with a white pigment added. A first example in which a red pigment was added and a second example in which a red pigment was added were used. In addition, the board is a 0.6mm thick glass-based epoxy board, and soldering is done according to the reflow method.
Heating was performed at 380°C, and the temperature of the substrate surface was measured over time. The results are shown in Figure 3a. Also,
At the same time as measuring the temperature on the substrate surface, we also measured the temperature rise inside the electrolytic capacitor over time. The results are shown in Section 3b.

In Figures 3a and 3b, solid line A represents the conventional example, broken line B represents the first embodiment using a white insulating plate, and thin line C represents the second example using a red insulating plate. It shows.

As is clear from Figure 3a, the first and second
When soldering is performed by the reflow method according to the embodiment, the surface temperature of the board is lower than that of the conventional example.
Both are high and the time required for the temperature to rise to the temperature required for soldering is short. Furthermore, the temperature rise inside the electrolytic capacitor according to the first and second embodiments is suppressed to a lower level than that of the conventional example, as shown in FIG. 3b. In particular, compared to the conventional example, the maximum temperature of the first example using a white insulating plate is
It is understood that the temperature is about 10°c lower. Generally, colors such as white, red, yellow, and orange are said to absorb light, heat, etc. more easily than black. In the case of this example as well, compared to the conventional example using a black insulating plate, the heat during board mounting is less likely to be absorbed by the insulating board, and the temperature rise on the board surface is relatively accelerated. Seem.

Further, in the embodiment of this invention, thermoplastic synthetic resin such as polyethylene terephthalate is used for the insulating plate 5, but thermosetting synthetic resin such as phenol may also be used.

Further, the shape of the insulating plate is not limited to that shown in the embodiments, and may be any shape.

[Effects of the device] As described above, this device attaches a sealing body to the opening of a bottomed cylindrical outer case that houses a capacitor element, and a coloring agent is added to the outer surface of this sealing body. Because it features an insulating plate made of heat-resistant synthetic resin, it is possible to create a leadless electrolytic capacitor compatible with printed circuit boards with a face bonding structure without making any changes to the structure of conventional electrolytic capacitors. can.

Furthermore, the coloring agent added to the insulating plate made of the heat-resistant synthetic resin is characterized in that it is a white, red, yellow, or orange pigment or dye, or a mixture of the above pigments or dyes. When the resulting electrolytic capacitor is surface-mounted on a board, the insulating plate, which transfers heat more easily than the conventional insulating plate made of black heat-resistant synthetic resin, can suppress the transfer of soldering heat. Therefore,
Thermal deterioration of the electrolytic capacitor during board mounting can be suppressed to a minimum, making it easier to maintain reliability.

Furthermore, by suppressing the transfer of soldering heat, the temperature rise on the substrate surface can be relatively promoted. Therefore, the surface mounting process becomes easy and the process time can be shortened.

As described above, this invention is a useful invention for realizing a leadless electrolytic capacitor without changing the conventional structure.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing a completed state of a leadless electrolytic capacitor according to an embodiment of this invention, and FIG. 2 is a perspective view showing the external shape of an insulating plate used in an embodiment of this invention. FIG. 3a is a graph showing changes in the surface temperature of the board due to reflow soldering, and FIG. 3b is a graph showing changes in temperature inside the electrolytic capacitor. 1... Capacitor element, 2... Electrode foil, 3...
Electrolytic paper, 4...Exterior case, 5...Lead, 6...
... Sealing body, 7 ... Insulating plate, 8 ... Through hole, 9 ... Terminal.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A sealing body is attached to the opening of a bottomed cylindrical outer case that houses a capacitor element, and a heat-resistant synthetic material with a coloring agent added to the outer surface of the sealing body. An electrolytic capacitor characterized by an insulating plate made of resin. (2) The scope of the utility model registration claim, characterized in that the coloring agent added to the insulating plate made of heat-resistant synthetic resin is a white, red, yellow, or orange pigment or dye, or a mixture of the above pigments or dyes. The electrolytic capacitor according to item 1.