JPS62213229A - Metallized film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to metallized film capacitors used in electronic and electrical equipment.

2. Description of the Related Art In recent years, efforts have been made to make electronic and electrical equipment multi-functional and miniaturized, and the electronic components used therein are becoming lighter, thinner, shorter and smaller. A typical example is chip technology. Therefore, the surface mounting method, which is different from the conventional method for mounting components on printed circuit boards that constitute circuits, has rapidly progressed. In this method, parts are fixed to one or both sides of a board with adhesive or cream solder, and soldered by passing them through a solder bath or high-temperature furnace. Therefore, the component body is directly exposed to high temperatures, and the temperature applied to the component body is much higher than that of a conventional lead-equipped component in which only the lead wires are immersed in a solder bath. For example, in the case of a film capacitor, when only the lead wires are soldered using a conventional lead type, the internal temperature of the capacitor is 1oO to 1
30"C, whereas the internal temperature of a chip film capacitor is 210-240C, which is about 100"C higher. Furthermore, in order to miniaturize the equipment, we are using methods to reduce the space inside the equipment and increase the board configuration density, so active electronic components (XG,
The heat generated by the devices (runsisters, diodes, etc.) is trapped inside the device, causing the temperature to rise.

As described above, tip parts are subject to harsher temperatures than conventional leaded parts. Film capacitor is
Conventionally, polyethylene terephthalate (hereinafter referred to as P) was used as a dielectric material.
ET), polypropylene (hereinafter abbreviated as PP), etc., but they had problems in terms of heat resistance, and a new plastic material with excellent heat resistance was desired.

Recently, polyphenylene sulfide (hereinafter abbreviated as PPS) and polyphenylene oxide (hereinafter abbreviated as PPO) have been developed as heat-resistant dielectric materials. pps and PP
O has superior heat resistance compared to PICT and PPK, and also has superior electrical properties, which is one of the major characteristics of film capacitors.

Problems to be Solved by the Invention However, in chip-type film capacitors in which a conventional double-sided metallized PPS film has a composite film formed with 220 layers on at least one side, the heat shrinkage rate of the composite film is uneven. However, soldering sometimes has the following problems.

(1) During soldering, the composite film undergoes thermal deformation due to the heat generated, and the electrode facing width 4 and element length 6 shown in Figure 1 shrink or expand due to the heat, and the electrode area changes. . Therefore, the capacitance of the capacitor changes.

(1) Similarly, when the composite film undergoes thermal deformation due to the heat during soldering and, for example, shrinks, wrinkles are formed in the composite film due to the shrinkage. 6th
The diagram shows the configuration of the element after soldering. Because the original element width 10 is shrunk 11, it becomes wrinkled as shown in the figure, and the distance 12 between the electrodes increases.

Therefore, the capacitance of the capacitor is reduced. In addition, 1
2 is a composite film in which 220 layers 2 are formed on both sides of a double-sided metallized PPS film, 3 is a metallic electrode, and 7 is an exterior resin.

Furthermore, when stretched, the stretched composite film 1
Since it tries to spread while surrounded by the exterior resin γ, it receives a reaction force from the exterior resin 7, and eventually wrinkles are formed in the composite film 1. FIG. 7 shows a configuration diagram of the element after soldering. The element width 10 is a value fixed by the exterior resin 7.

When the composite film tries to spread, a force equal to the spreading force becomes a reaction force υ from the exterior resin 7, which becomes a force that tries to shrink the composite film 1, and finally, It becomes wrinkled as shown in the figure, and the distance between the electrodes is 12
Expand. Therefore, the capacitance of the capacitor decreases.

In this way, soldering has a large change in capacitance before and after.
However, it had the disadvantage of causing variations in the quality.

Particularly in laminated film capacitors, the composite film changes in both the vertical and lateral directions due to heat, so this rate of change was remarkable.

In view of the above-mentioned drawbacks, the present invention provides a metallized film capacitor having stable characteristics with little change in capacitance before and after soldering.

Means for Solving the Problems In order to achieve this object, the metallized film capacitor of the present invention is made of double-sided metallized PPS having a heat shrinkage rate of 7% to 7% in both the width and length directions at 230°C. A composite film in which 220 layers are formed on at least one side of the film is used.

In order to obtain the above-mentioned heat shrinkage rate, for example, heat aging or the like can be used.

Effect: With this structure, a composite film in which a PPO layer is formed on at least one side of a double-sided metallized PPS film has less thermal deformation due to heat during soldering, and (1) less change in the area facing the electrodes of the metallized film capacitor. However, the change in capacitance of the capacitor becomes stable.

(1) Wrinkles that occur when the composite film contracts or expands are reduced, the distance between the electrodes of the film capacitor changes slightly, and the capacitance change of the capacitor becomes stable.

This effect can be obtained.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 shows the element structure of a metallized film capacitor in one embodiment of the present invention.

Double-sided metallized PP with heat shrinkage rate of 17 to +7% at 230'C
A plurality of composite films 1 each having 220 layers 2 formed on both sides of an S film are laminated, and metal electrodes 3 are provided at the ends by metal spraying. Here, 1-1 indicates the metallized electrode, 4 indicates the electrode facing width, and 6 indicates the element length.

FIG. 2 shows a completed perspective view of the element shown in FIG. 1 covered with resin. 6 is a capacitor element, 7 is an exterior resin, and 8 is an external electrode. The metallized film capacitor obtained in the above manner was soldered at 26"C using the dip method during mounting.
Soldering was performed by immersing it in molten solder for 6 to 10 seconds. At this time, the heat received by the capacitor element 6 is approximately 21
The temperature was 0 to 4°C.

Figure 3 shows the measured thermal shrinkage rate at this temperature of a composite film with 220 layers formed on both sides of a double-sided metallized pps film (the measurement method is JIS-C-23186j,
5), the temperature of the constant-humidity seed box was changed. here,
It can be seen that the heat shrinkage rate changes significantly around 230"C. As seen above, the heat shrinkage rate of the composite film at 230"C is a very important characteristic for metallized film capacitors. ing.

Next, the heat shrinkage rate at 230℃ is different as shown in the table below.
A chip-type metallized film capacitor was created using a composite film with 220 layers formed on both sides of a type of double-sided metallized PPS film. Shown in Figure 4.

The horizontal axis represents each sample, and the vertical axis represents the rate of change between the capacitance before and after immersion in the solder. As shown in the results shown in Figure 4, the metallized film capacitors (Sample M and Sample B) made using the composite film with a heat shrinkage rate of less than 17% at 230' The rate of capacitance change was large in the negative direction and had variations. That is, when the thermal shrinkage rate is less than 17%, the composite film is stretched by heat. However, since it is surrounded by resin, it cannot spread, and this spreading force is applied to the resin, and on the contrary, this force acts as a reaction force that tries to shrink the composite film, so that the composite film eventually shrinks. This causes wrinkles and widens the distance between the electrodes of the metallized film capacitor, resulting in a large change in capacitance, which changes in the negative direction.
Moreover, there is variation. In addition, the metallized film capacitors (Sample F and Sample G) made using the above-mentioned composite films with a heat shrinkage rate of more than +7% have a large negative capacitance change rate before and after solder immersion, and also have variations. was. In other words, the composite film, which has a heat shrinkage rate of +7%, shrinks due to heat, causing wrinkles in the composite film and widening the distance between the electrodes of the metallized film capacitor, resulting in a large change in capacitance in the negative direction. It has variations. The metallized film capacitors Sample C, Sample D, and Sample 2 of the present invention, which were made using the composite film having a heat shrinkage rate of 17% to 7% at 230°C, showed stable capacitance changes even after being immersed in solder. It had become.

As described above, according to this example, a composite film is used in which PPO layers are formed on both sides of a double-sided metallized PPS film whose heat shrinkage rate at 230°C is 17 to 7% in both the width and length directions. If a laminated metallized film capacitor is used, stable capacitance characteristics can be obtained even after immersion in solder.

In this example, 22 mm was applied to both sides of the double-sided metalized film.
Although the structure is made by laminating a plurality of composite films each having a 0 layer, the present invention is not limited to this, but a plurality of composite films 9 each having a 220 layer 2 formed on one side of a double-sided metallized pps film as shown in FIG. 6 may be used. It goes without saying that a laminated structure may also be used.

As described above, the film capacitor of the present invention has a temperature of 230°C.
This is a laminated metallized film capacitor using a composite film with 220 layers formed on at least one side of a double-sided metallized PPS film with a heat shrinkage rate of 17% to 7% in both the width and length directions, so it cannot be soldered. Even when exposed to the heat of time, it is possible to obtain stable capacitance characteristics, and its effects on industry are truly significant.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the element structure of a double-sided metalized film capacitor according to an embodiment of the present invention, FIG. 2 is a perspective view of a completed product of a metalized film capacitor according to an embodiment of the present invention, and FIG. A characteristic diagram showing the thermal shrinkage rate of a metallized PPS film, FIG. 4 is a characteristic diagram for explaining the present invention in detail, and FIG. 6 shows an element structure of a metalized film capacitor in another embodiment of the present invention. The perspective view, FIG. 6, and FIG. 7 are cross-sectional views of a capacitor element for explaining the conventional technology. 1...pp on both sides of double-sided metallized PPS film
. Composite film with layers formed, 2...ppo layer,
6...Capacitor element, 9...Composite film with 220 layers formed on one side of a double-sided metallized PPS film. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
--Double-sided Kei belonging F'rS 7A Both sides 1; FPO eyebrow 1 8+ film Z-FPOli Figure 1 Figure 2 Figure 3 Temperature Ji Figure 6 Figure 7

Claims (2)

[Claims] (1) Form a lacquer layer on at least one side of a double-sided metallized polyphenylene sulfide film to make a composite film, and confirm that the heat shrinkage rate of the composite film at 230°C is -7 to 7% in both the width and length directions. Features of metallized film capacitors. (2) A metallized film capacitor according to claim 1, wherein the lacquer layer comprises polyphenylene oxide.