JPH01246761A - Flat cell - Google Patents

Abstract

PURPOSE:To prevent a flat cell from such as being electrically shorted after installing it in a flat electronic equipment and improve its reliability by coating outer surface of a positive and negative terminal board other than the connection portion thereof to external terminals with ultraviolet hardening type resin. CONSTITUTION:Entire outer surface of positive and negative terminal boards 36 and 37 of a flat cell 31 other than the connection portion thereof to external terminals 13 and 14 is coated with insulative film 38 made of ultraviolet hardening type resin. Thus, after the flat cell 31 is installed in a flat electronic equipment, electrical conduction or short-circuit between metal substrate 15 for strengthening the flat cell 31 and resin sheets 12a and 12b due to bending or partial pressing thereof or leakage of electrolyte are prevented. Therefore, reliability of the flat cell 31 is improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a flat battery.

C. Prior Art] In recent years, as electronic devices such as electronic desktop calculators and electronic wristwatches have become smaller and thinner, there has been an increasing demand for the development of extremely thin flat batteries.

In particular, as a power source for card-type electronic devices such as card-type calculators and IC cards, ultra-thin batteries with a thickness of less than IB are desired.

By the way, as the above-mentioned flat battery, for example, a flat battery 1 having a structure shown in FIG. 3 has been proposed. That is, the third
In the flat battery 1 shown in the figure, a negative electrode sheet 2 and a positive electrode mixture sheet 3 are laminated with a separator 4 in between to form a power generation unit. In the power generation unit made of this laminate, a frame-shaped insulating sealing body 5 is arranged so as to surround the unit. A negative electrode terminal plate 6 is provided on one frame-shaped surface of the insulating sealing body 5 and on the lower surface of the negative electrode sheet 2.
A positive electrode terminal plate 7 is formed in close contact with the other frame-shaped surface of the frame-shaped surface and the upper surface of the positive electrode mixture sheet 3 via, for example, an adhesive, and the above-mentioned power generation The unit is sealed.

FIG. 4 shows the above-mentioned flat battery 1 being used in a card-type electronic device (
FIG. 3 is a vertical cross-sectional view showing a state where the device is built into an IC card (for example, an IC card). That is, numeral 11 in the figure is a circuit sheet on which the flat battery 1 and other elements (for example, an integrated circuit chip, not shown) are mounted. This circuit sheet 11 is sandwiched between plastic sheets 12a and 12b made of vinyl chloride resin or the like. These plastic sheets 12a,
12b constitutes a card as a whole depending on whether it is adhered to the circuit sheet 11 with an adhesive or its peripheral portion is heat-sealed. The positive and negative electrode terminals 7.6 of the flat battery l built in the plastic sheet 12a 512b and the circuit chip on the circuit sheet 11 are as follows:
They are electrically connected by elastic lead terminals 13 and 14, respectively. The positive and negative terminals 7.6 and lead terminals 1
3.14 electrical connections are made using welding or conductive tape. Note that such IC cards are bent due to stress during transportation or use, and there is a risk that elements such as integrated circuits inside the card may lose their functions, so they are usually bent as shown in Figure 4. A base body 15 made of a thin metal plate is inserted into the card to increase its strength, thereby preventing the card from curving as much as possible. In addition, for the purpose of further increasing reliability, plastic sheets 12a and 12b are used.
The space surrounded by the flat battery 1, circuit sheet 11, and other elements and parts is filled with an adhesive made of synthetic resin. The adhesive filled in this way not only improves mechanical strength against bending, etc.
Preventing the built-in flat battery 1 from shifting
This prevents the metal from coming into contact with the circuit sheet 11 or the metal base 15 and causing an external short circuit.

However, when manufacturing the above-mentioned IC card, the IC card IS
O standard) plastic sheet 12a,
After filling the space surrounded by 12b with an adhesive made of synthetic resin, the adhesive is cured while being pressurized, so that the positive terminal plate 7 of the flat battery 1 comes into contact with the metal base 15 and becomes electrically conductive. Ru. The metal base 15 is also in contact with the circuit sheet 11, and if the IC card is bent or partially pressurized, electrical continuity will be lost between the circuit sheet 11 and the metal base 15. There are things you can do. In this case, if the opposite pole to the positive terminal plate 7 with which the metal base 15 is in contact is located on the circuit sheet 11, a short circuit will occur at this location and the IC card will not operate. Furthermore, even if the metal base 15 is protected with an insulating coating, if it is repeatedly bent, the edge of the positive terminal plate 7 of the flat battery l will break the coating, causing a short circuit as described above, and causing an IC card. will stop working.

On the other hand, a flat type battery having a structure shown in FIG. 5 (Japanese Patent Application Laid-Open No. 61-256559) is known. This flat battery has a frame-shaped insulating sealing body 24 arranged to surround a power generation unit in which a negative electrode sheet 21, a separator 22, and a positive electrode mixture sheet 23 are laminated, and the insulating sealing body 2
A negative terminal plate 25 and a positive terminal plate 2B are attached to the frame-shaped surfaces on both sides of 4.
For example, the positive and negative electrode terminal plates 26 and 25, excluding the insulating sealing body 24, are covered with resin thin films 27a and 27b in order to further increase the strength against partial pressure. ing.

However, when the flat battery shown in FIG. 5 is incorporated into the above-mentioned card-type electronic device (IC card),
As described above, there was a problem in that the exposed portion of the positive electrode terminal plate 26 above the insulating sealing body 24, which is not covered, comes into contact with the metal base 15, causing an external short circuit. Furthermore, if stress is applied to the flat type battery shown in FIG. 5 built into the device due to bending when an IC card is used, etc., the internal electrolyte may leak between the positive and negative terminal plates 26, 25 and the insulating seal. There was a risk of leakage from the adhesive surface with the body 24.

The present invention was made in order to solve the conventional problems, and prevents electrical conduction and short circuit with a metal substrate used for the purpose of improving the strength of thin electronic devices after being incorporated into the devices. The purpose of this invention is to provide a highly reliable flat battery that is flexible and prevents electrolyte leakage due to bending of the device.

[Means for Solving the Problems] The present invention provides a laminate in which a positive electrode mixture sheet, a separator, and a negative electrode sheet are laminated in this order, a frame-shaped insulating sealing body surrounding the laminate, and the positive electrode. Consisting of a positive terminal plate that covers the surface of the mixture sheet and the end face of the insulating sealing body and comes into close contact therewith, and a negative terminal plate that covers the surface of the negative electrode sheet and the other end face of the insulating sealing body and comes in close contact with them. The flat battery is characterized in that the outer surface of the positive and negative terminal plates except for the connecting portions with external terminals is coated with an insulating film made of an ultraviolet curable resin.

Examples of the ultraviolet curable resin include acrylic, polyester, and epoxy resins. In order to cure such ultraviolet curable resin, 300~
Irradiation with ultraviolet radiation in the spectral range of 400 na+ is effective. Specifically, it is desirable to perform curing by irradiating for about 1 to 60 seconds using a mercury lamp or the like of about 50 to 200 W.

In order to coat the outer surface of the positive and negative terminal plates except for the connection parts with the external terminals with an insulating film made of ultraviolet curable resin, for example, the connection parts with the external terminals of the positive and negative terminal plates are masked, and the ultraviolet curable The resin solution may be applied to the entire surface with a brush or spray, or the resin solution may be chipped with ultraviolet rays and then cured by irradiation with ultraviolet rays. The thickness of the insulating film coated in this way is 5 to 50 μm.
It is desirable to set it to m. The reason for this is that the thickness is 5μ
If the thickness is less than 50 μm, pinholes and tears are likely to occur, leading to a decrease in insulation. On the other hand, if the thickness exceeds 50 μm, the total thickness of the battery itself becomes too thick, making it difficult to incorporate it into thin electronic devices. In order to achieve the required thickness, it is necessary to make the internal power generation unit thinner, which may reduce the discharge capacity.

In addition, in the present invention, an insulating coating is formed on the outer surface of the positive and negative terminal plates except for the connecting portions with external terminals by using a ceramic coating agent mainly containing metal alcolade instead of the ultraviolet curable resin. Good too. As a means of coating with such an insulating film, for example, the connection portions of the positive and negative terminal plates with external terminals are masked, and a ceramic coating agent is applied to the entire surface with a brush or spray, or after chipping the ceramic coating agent, water, alcohol,
Hydrolysis and polycondensation reactions occur at or near room temperature in the coexistence of a catalyst to form a sol, and as the reaction progresses, it becomes a gel, and this gel is further heated at 100 to 300°C to form an insulating coating made of amorphous ceramic. It is possible to adopt a method of forming Such a reaction is expressed by the following formula (1),
It is expressed by equation (2).

Me (OR) rL+ll H20 →M6 (OH)n +rLR(OH) ”・(1
)Me (OH) n−”MeO+ H20・=(2
) However, in the formula, Me represents a metal such as Si, TI, Al, Zr, etc., and R represents an alkyl group such as C2H5 or C3H7.

[Function] According to the present invention, by coating the outer surface of the positive and negative terminal plates except for the connecting portions with external terminals with an insulating film made of ultraviolet curable resin, the The insulating coating prevents electrical conduction with a metal substrate used for the purpose of improving the strength of the device, thereby preventing short circuits. In addition, if stress due to the bending of the thin electronic device is applied to the battery built into the device, most of the outer surface of the battery except for the connection part with the external terminal is coated with an insulating coating. It is possible to prevent the electrolyte inside the battery from leaking from the interface between the positive and negative terminal plates and the insulating sealing body. Furthermore, since UV-curable resins can be cured in a short time by UV irradiation to form an insulating film, the insulating sealing body made entirely of thermoplastic resin will melt when heat-cured, and the sealing body and the positive and negative terminals will melt. Leakage of electrolyte from the slave plate interface can be prevented.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

In a flat battery 31 shown in FIG. 1, a negative electrode sheet 32 made of lithium and a positive electrode mixture sheet 33 made of a mixture of manganese dioxide, graphite, and polytetrafluoroethylene are laminated with a separator 34 in between to form a power generation unit. There is. In the power generation unit made of this laminate, a frame-shaped insulating sealing body 35 made of, for example, an ionomer resin is disposed to surround the unit. A stainless steel negative electrode terminal plate 36 of 20 u x 40 rttm x 0.05 g is placed on one frame-shaped surface of the insulating sealing body 35 and on the lower surface of the negative electrode sheet 32 . 20MX 40MX 0.0
A 5 mm stainless steel positive electrode terminal plate 37 is closely formed with, for example, an adhesive, and the power generation unit is sealed by the frame-shaped insulating sealing body 35 and the positive and negative electrode terminal plates 37 and 36. The entire outer surface of the positive and negative terminal plates 37, 36 except for the connecting portions with external terminals is coated with an insulating coating 38 made of ultraviolet curable resin and having a thickness of 5 μm. This insulating coating 38 connects the power generation unit to the positive and negative terminal plates 37.
3B and the insulating sealing body 35, the positive and negative terminal plates 3
7. Mask the connection part with the external terminal of 3B, and set the viscosity to 4.
00cm Boise epoxy type ultraviolet curable resin solution, removed unnecessary resin solution to a predetermined thickness, and continued at 100V.

ioo w mercury lamp, irradiation distance 12oz, irradiation time 10
It was formed by curing the resin under conditions of seconds.

The flat battery 31 of this embodiment is mounted in a thin electronic device (IC card) shown in FIG. 2, and the positive and negative terminal plates 37.3B of the battery 31 are used as lead terminals 14
．． 13, the operation of bending the thin electronic device by pressing it against a cylinder having a radius of curvature of 150 H was repeated 10,000 times to check the operation.

The IC card shown in FIG. 2 has the same structure as that shown in FIG. 4 described above except for the flat battery 31 mounted thereon. The operation check was performed on 10 IC cards, and if even one of them had malfunction, it was judged as unacceptable. Further, after the IC card was repeatedly bent, the discharge capacity of the flat battery built into the card was measured. These results are shown in Table 1 below.

In Table 1, as a comparative example, the results of the bending test for an IC card containing a flat battery not covered with an insulating thin film and the discharge capacity of the flat battery are also listed.

Table 1 As is clear from Table 1 above, the positive and negative terminal plates 37.36
The IC card with a built-in flat battery of this embodiment, whose entire outer surface except the connection part with the external terminal is coated with an insulating coating 38 made of ultraviolet curable resin with a thickness of 5 μm, was subjected to a bending test of 10,000 times. It can be seen that no abnormal operation was observed even after the test, and that the device had a good discharge capacity.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to prevent electrical conduction and short circuits with a metal substrate used for the purpose of improving the strength of a thin electronic device after it is incorporated into the device. In addition, it is possible to provide a highly reliable flat battery that prevents electrolyte leakage due to bending of the device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a flat battery showing an embodiment of the present invention;
Figure 2 is a cross-sectional view showing an IC card incorporating the flat battery shown in Figure 1, Figure 3 is a cross-sectional view showing a conventional flat battery, and Figure 4 is a cross-sectional view showing the IC card incorporating the flat battery shown in Figure 3. FIG. 5 is a sectional view showing another conventional flat battery. 11...Circuit sheet, 12a, 12b...Resin sheet, 13.14...Lead terminal (external terminal), 1
5... Metal base, 31... Flat battery, 32...
Negative electrode sheet, 33... Positive electrode mixture sheet, 34... Separator, 35... Frame-shaped insulating sealing body, 36... Negative electrode terminal plate, 37... Positive electrode terminal plate, 38... Insulating coating . Figure 5

Claims (1)

[Claims] A laminate in which a positive electrode mixture sheet, a separator, and a negative electrode sheet are laminated in this order, a frame-shaped insulating sealing body surrounding the laminate, and a surface of the positive electrode mixture sheet and an end face of the insulating sealing body. a positive terminal plate that covers and comes into close contact with these;
In a flat battery comprising a negative electrode terminal plate that covers and is in close contact with the surface of the negative electrode sheet and the other end face of the insulating sealing body, an ultraviolet curing type is applied to the outer surface of the positive and negative electrode terminal plates except for the connecting portions with external terminals. A flat battery characterized by being coated with an insulating film made of resin.