JPH0719717B2 - Capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a capacitor used in electronic equipment and electric equipment,
Among them, it relates to film chip capacitors.

2. Description of the Related Art In recent years, efforts have been made to increase the functionality and size of electronic devices and electric devices, and the electronic components used for these devices have become light, thin, short and small. A typical example is chipping. Therefore, the surface mounting method, which is different from the conventional one, has been rapidly progressing as the method of mounting the components on the printed circuit board constituting the circuit. In this method, soldering is performed by fixing components to one side or both sides of the substrate with an adhesive or cream solder, and passing the components through a solder bath or a high-temperature furnace. Therefore, the component body is directly exposed to a high temperature, and the temperature applied to the component body becomes much higher than that of the conventional leaded component in which only the lead wire is immersed in the solder bath. For example, in the case of a film capacitor, the internal temperature of the conventional leaded type is 100 to 130 ° C when only the lead wire is soldered, whereas the internal temperature of the chip film capacitor is
It is 210-240 ℃, about 100 ℃ higher. Furthermore, in order to downsize the equipment, the space inside the equipment is reduced and the board configuration density is increased, so heat generated by active electronic components (ICs, transistors, diodes, etc.) The temperature rises.

As described above, the temperature of the step component is severer than that of the conventional leaded component. Film capacitors
Polyethylene terephthalate (hereinafter PE
Although abbreviated as T), polypropylene (abbreviated as PP hereinafter) and the like were used, a new plastic material having excellent heat resistance was desired because of difficulty in heat resistance.

Recently, polyphenylene sulfide (hereinafter abbreviated as PPS) and polyphenylene oxide (hereinafter abbreviated as PPO) have been developed as heat resistant dielectric materials. PPS and PPO are PET, P
It has better heat resistance than P and also has excellent electrical characteristics, which is one of the major characteristics of film capacitors.

Conventionally, a laminated type film chip capacitor was obtained by forming vapor-deposited electrodes made of aluminum on both surfaces of a dielectric film made of polyphenylene sulfide and further making a thin coating dielectric made of polyphenylene oxide on both surfaces. Laminating hundreds of long and narrow double-sided vapor-deposited double-sided coating films, and after forming a metallicon layer consisting of an aluminum bronze as the lower layer and a tin-lead alloy as the upper layer to obtain electrical connection from the vapor deposition electrodes, cut it to a certain size. It does not form a laminated film capacitor element, and the external electrodes are welded, epoxy resin is poured into a mold of a certain size, and the resin is heat-cured to perform the mold exterior. Then, the external electrodes were processed to obtain a laminated film chip capacitor.

Problems to be Solved by the Invention The characteristics of the multilayer film chip capacitor are that the temperature change and frequency change of the capacitance are small and the loss angle is small, but since the high dimensional accuracy is required, the element is a rectangular parallelepiped. However, it is necessary to carry out the exterior of the mold, which has the drawbacks of increased shape and increased cost. As an improvement method, there is a method of directly applying epoxy resin to the laminated film capacitor element and heating and curing, but the thickness variation is very large due to the high surface tension of the epoxy resin or the low viscosity at high temperature, and the dimensional accuracy is significantly reduced. Because it did, it was not practical.

An object of the present invention is to overcome the above problems and provide a small-sized film capacitor.

Means for Solving the Problems In order to achieve this object, the present invention provides an exterior member on at least two cut surfaces of a film capacitor element having a capacitor portion and protective layers provided above and below the capacitor portion. Set up
In addition, at least the surface layer portion of the protective layer is colored black by crosslinking the resin of the protective layer.

With this configuration, a small-sized film chip capacitor can be obtained, and at least the surface layer of the protective layer is black, so that infrared absorption is good in reflow soldering using an infrared heater. Since the temperature of the element easily rises, the solderability at the time of mounting is improved.

Examples The contents of the present invention will be described in more detail based on the following examples.

FIG. 1 is a perspective view showing a cross section of a part of a laminated film chip capacitor according to an embodiment of the present invention. The vapor deposition electrodes 2 and 3 made of aluminum having a thickness of about 400 Å are provided on both sides of the dielectric film 1 made of a PPS film having a thickness of 2 μm and having a width of 5 mm, and further, the thickness made of PPO is about 1
Forming coating dielectric films 4 and 5 of μm on both sides,
Double-sided coated film is made, then 500 sheets of double-sided vapor-deposited and double-sided coated film are laminated, and the electrode lead-out portion 6,7 is used to pull out the electrode from the vapor-deposited electrodes 2,3.
To obtain a long-length strip capacitor. After that, cut into widths of about 4.6 mm to make individual unit capacitors, and then cut the two surfaces, which are cut surfaces, as shown in Fig. 2.
15-50μm thickness on 25-75μm polyimide film 8a
After attaching a thermosetting sheet called a prepreg sheet on which the epoxy resin layer 8b is formed, it is heat-cured to form the exterior member 8 with a capacitance of 0.10 μF, a height of 2 mm, and a width of 6 mm,
A laminated film chip capacitor having a length of 5 mm was obtained.

Here, as shown in FIG. 1 and FIG.
A protective layer 9,10 is provided above and below the capacity part where double-sided coating films are laminated to protect the capacity part and to reinforce the whole part.
Is provided. The protective layers 9 and 10 are made of a resin film 11 such as a PPS film, similar to the film forming the capacity portion.
Is formed by laminating a film having a resin film 12 made of PPO formed on both surfaces thereof. The exterior member 8 has a width that covers the entire end surface of the capacitance portion and is arranged over the entire area or a partial area of the end surface of the protective layers 9 and 10. As an example, the protective layers 9 and 10 having a thickness of 0.15 mm are provided, and the width of the exterior member 8 is set to the protective layers 9 and 10.
The width is 0.10 mm shorter at the top and bottom than the overall thickness of the. The exterior member 8 also has such a length that it is arranged over the entire area or a partial area of the end surface on the cut surface side of the electrode lead-out portions 6, 7.

Further, at least the coating dielectric film 4,5 resin film 12 of the protective layers 9 and 10 and the capacitance portion is colored with brown to blackish brown black at least the surface layer portion by crosslinking the resin such as PPO which is a constituent material. is doing. The surface layer of the exterior member 8 is also colored in black to brown to blackish brown.

Furthermore, the electrode lead-out portions 6 and 7 have a first layer 6a and 7a formed by spraying a copper-zinc alloy with a thickness of 0.15 mm and a second layer 6b and a second layer 6b formed by spraying solder with a thickness of 0.25 mm. 7b and. In the first layers 6a, 7a and the second layers 6b, 7b of the electrode lead-out portions 6, 7, the first layers 6a, 7a have a thickness of 0.10 mm to 0.20 mm.
Therefore, it is preferable to use a copper-zinc alloy having a zinc component ratio of 5% to 60% by weight, and the second layers 6b and 7b have a thickness of
It is preferable to use a solder (Sb-Pb-Sn alloy) having a liquidus temperature of 195 ° C to 215 ° C and a solidus temperature of 189 ° C with a thickness of 0.20 mm to 0.40 mm.

FIGS. 4 and 5 show a state in which the laminated film chip capacitor according to this embodiment is mounted on a printed board. As shown in FIGS. 4 and 5, a chip capacitor 15 is arranged on a printed circuit board 14 having a wiring pattern 13, and soldering by dipping in a solder bath or soldering by a reflow method is performed. The electrode lead-out portions 6 and 7 of 15 are connected to the wiring pattern 13 by solder 16.

At this time, the bottom central portion 15a of the chip capacitor 15 is curved inward so that when the chip capacitor 15 is arranged on the printed board 14, the bottom central portion 15a of the chip capacitor 15 and the printed board 14 are A gap will be formed in the chip capacitor 15 and the printed circuit board 14
The adhesive 17 for temporarily fixing the wiring pattern 13 on the upper side is prevented from protruding laterally, and the wiring pattern 13 and the electrode lead-out portion
It does not hinder the connection with 6,7.

Such a laminated film chip capacitor obtained by this example has a volume reduced by about 43% as compared with a conventional laminated film chip capacitor (height: 3 mm, width: 7 mm, length: 5 mm) which is provided with a mold exterior. The dimensional accuracy was the same. In addition, 100 of these laminated film chip capacitors were adhered to a printed wiring board and soldered at a temperature of 260 ° C for a time of 5 seconds. As a result, the cracking failure rate of the exterior was 0% and the change in capacitance was within ± 1%, which was good. Met.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

That is, a small-sized film chip capacitor can be obtained, and at least the surface layer of the protective layer is black, so that infrared rays can be absorbed well in reflow soldering using an infrared heater and the temperature of the element can be reduced. The solderability at the time of mounting will be improved since the temperature rises easily.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of a laminated film chip capacitor according to an embodiment of the present invention in section, FIG. 2 is a perspective view showing a sheet used for the capacitor, and FIG. 3 is a schematic view of the capacitor. 4 and 5 are a perspective view and a side view showing a state in which the same capacitor is mounted on a printed circuit board. 1 ... Dielectric film, 2,3 ... Vapor-deposited electrode, 4,5 ... Coating dielectric film, 6,7 ... Electrode extraction part, 6a, 7a ... 1st
Layer, 6b, 7b ... Second layer, 8 ... Exterior member, 8a ... Polyimide film, 8b ... Epoxy resin layer, 9,10 ... Protective layer, 11 ... Resin film, 12 ... Resin film, 13 …… wiring pattern, 14 …… printed circuit board, 15 …… chip capacitor, 15a …… bottom center, 16 …… solder, 17 …… adhesive.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuki Sunagure 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Atsushi Kojima, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Kenji Kuwata 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. An exterior member is provided on at least two cut surfaces of a film capacitor element having a capacitive portion and protective layers provided above and below the capacitive portion, and at least a surface layer portion of the protective layer is a protective layer. Capacitor colored black by cross-linking the resin of.