JPS6156859B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic device and a method for manufacturing the same, and more particularly to the inclusion and extraction of electrodes in a flat electronic device.

In recent years, electronic devices such as calculators and electronic watches have been becoming smaller, especially thinner. Therefore, capacitors, resistors, semiconductors,
Electronic devices such as batteries are also required to be thinner and flat products. This type of electronic device is easily deteriorated by gases such as oxygen and nitrogen in the air, and water vapor, so it is necessary to encapsulate the electronic device in an electrical insulator such as glass or synthetic resin to isolate it from the outside air. Conventional encapsulation methods include immersion methods in which electronic devices are immersed in a viscous liquid of synthetic resin such as epoxy and cured by heat, or a hot molten liquid of synthetic resin such as epoxy is placed in a mold of a certain shape containing the electronic device. The so-called molding method is mainly used, in which the material is extruded under pressure, encapsulated, and then cured by heat. The dipping method has the disadvantage that it is difficult to control the thickness of the encapsulated resin at a constant level, and the thickness varies widely, making it impossible to produce products with a uniform shape. For this reason, electronic elements encapsulated by the immersion method are not suitable for use in small and thin electronic devices that require strict dimensions. On the other hand, electronic elements encapsulated using the molding method are molded in a mold with a fixed shape, so an electronic element with constant external dimensions can be obtained.
Electrical properties are often significantly degraded by mechanical and thermal stresses such as the pressure of the resin extruded during molding, the heat of the molten resin, and the heat during curing. Further, since the electronic element is molded by pushing resin into the mold, the electronic element contained within the resin layer is exposed from the resin layer even if the positioning of the electronic element and the dimensional accuracy of the mold are well taken care of. For this reason, the thickness of the resin encapsulated by the molding method has to be relatively thick. For this reason, it is not possible to obtain a shape that is fully satisfactory as an electronic element that is compatible with miniaturization and thinning. Furthermore, since the structure for drawing out the electrodes from the encapsulated electronic device to the outside becomes complicated, the structure of the mold for molding also becomes complex and highly precise, making it unsuitable for encapsulating electronic devices for mass production.

Among the electronic elements mentioned above, capacitors and
This is a drawback of conventional products related to resistors and semiconductors. Another electronic device that is most required to be smaller and thinner is a battery. Next, conventional drawbacks of batteries will be explained in detail with reference to the drawings.

Generally, a battery consists of a negative electrode active material 1 as shown in FIG.
The basic battery component (hereinafter referred to as battery element body 9) has a layered structure in which an electrolyte layer 2 is sandwiched between positive electrode active material 3 and
). Usually, this element body 9 is provided with electrodes, and the element body 9 is sealed so that the electrodes can be taken out from the outside. Due to the characteristics of the battery, the current value that can be taken out is also affected by the internal resistance of the battery, but if the internal resistance of the battery is the same, it is proportional to the contact area between the positive and negative amphoteric active materials 3 and 1 and the electrolyte layer 2. and grow bigger. Further, the life of the battery is proportional to the amount of materials included in the product of the positive electrode active material 3 and the negative electrode active material 1. Therefore, in order to design a battery with a large current value and a long life, the structure must be made into a sheet with a large contact area, or the sheet can be wound, but this is difficult in terms of thinning. A flat battery containing a sheet-shaped battery element is desirable.

BACKGROUND ART Conventionally, as a flat battery, there is a battery usually called a button shape or a coin shape. Although there are differences in the bottom area and thickness of the batteries, they all basically have the structure shown in Figure 1. The battery element body 9 is wrapped in a lid 4 made of negative electrode metal that also serves as an electrode and a case 5 made of positive electrode metal.
is electrically insulated by an electrically insulating packing 6, and the battery element body 9 has a sealed structure. This requires a specially constructed lid 4, case 5, and packing 6, and the case 5 is sealed through the packing 6 by a special machining process usually called caulking. Due to its complex structure, special parts and processing steps are required. Moreover, in order to increase the contact area between the electrolyte layer 2 and the active materials 1 and 3 of the negative and positive electrodes in order to increase the current value, there is a certain limit with a special structure as shown in Figure 1. Batteries with large values cannot be used. Furthermore, due to the special structure, there is a certain limit to how thin it can be made.

Recently, in order to increase the current value, a sheet-shaped battery with a relatively large area and thinner thickness has been developed. FIGS. 2 and 3 show cross-sectional views of conventional sheet-shaped batteries. FIG. 2 shows a battery in which the upper and lower sides of a battery element body 9 are covered with electrode layers of metal foils 7 and 7', and the metal foils 7 and 7' are electrically insulated via electrically insulating packing 8. It's in the structure. This is because (a) an electrical short circuit occurs when the upper and lower metal foils 7 and 7' are connected, so electrically insulating packing 8 is required to enclose the battery element 9; and (b) sufficient electrical insulation is required. In order to achieve this, the thickness of the packing 8 must be made relatively thick (c)
(d) The manufacturing process is complicated because it is difficult to align the packing 8 with the battery element body 9;
There are drawbacks such as relatively poor adhesion between the metal foils 7, 7' and the packing 8 made of synthetic resin, resulting in insufficient sealing.

As an example of another conventional product, as shown in FIG.
However, in this case, as shown in FIG. 2, the packing 8 becomes unnecessary and the adhesion is improved. On the other hand, it becomes complicated to take out the positive and negative external electrodes. In other words, as shown in Figure 2,
Similar to the metal foil 7 above the negative electrode active material 1, a metal foil 10 for the negative electrode layer is provided, and a metal foil 11 for the positive electrode layer is provided below the positive electrode active material 3, respectively. For this reason, (i) the external electrode cannot be removed unless the electrical insulating film 12 and -12' of the exterior casing are cut and removed at appropriate locations so that both electrode layers consisting of metal foils 10 and 11 are exposed to the outside of the battery. Can not. (ii) Therefore, the battery becomes thicker by the thickness of the metal foils 10 and 11 of the negative and positive electrode layers. (iii) Electrical insulation film 1
Since the adhesion between the metal foils 10 and 11 and the metal foils 10 and 11 is weak, the sealing is insufficient. There are drawbacks such as.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such conventional drawbacks, to provide an electronic device that has a thin layer, good sealing properties, and facilitates extraction of external electrodes, and a method for manufacturing the same.

That is, according to the present invention, the upper and lower surfaces of an element body such as a semiconductor, a resistor, a dielectric, a battery, etc., on which electrode parts are not formed, are anisotropically conductive, having conductivity in the thickness direction and electrical insulation in the surface direction. An electronic device is obtained, which is characterized in that it is closely encapsulated by a plastic sheet, the entire periphery of the device body is sealed, and the external electrodes are taken out.

Furthermore, element bodies such as semiconductors, resistors, dielectrics, and batteries on which electrode parts are not formed are placed inside two anisotropically conductive sheets that exhibit conductivity in the thickness direction and electrical insulation in the plane direction. After clamping, a method for manufacturing an electronic device is obtained, which is characterized in that the sheet around the device body is sealed.

Next, FIGS. 4 and 5 are cross-sectional views showing specific examples of anisotropically conductive sheets having conductivity in the thickness direction and electrical insulation in the surface direction. Figure 4 shows
The conductive thin wire 13 made of metal such as stainless steel or copper or carbon fiber is made of rubber elastic material such as butadiene rubber or silicone rubber, or made of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, nylon, polyimide, etc.
The thin wires 13 are embedded in a synthetic resin 14 having electrically insulating properties, such as plastic, in parallel and densely in the thickness direction to form a sheet or film.The thin wires 13 are exposed on the sheet surface. Therefore, although the sheet exhibits electrical insulation in the surface direction, it exhibits conductivity in the thickness direction of the sheet. Figure 5 shows copper,
It is a cross-sectional view of a sheet or film in which conductive grains 15 in the form of fine particles of metals such as iron, nickel, and silver or graphite are oriented and connected in the thickness direction in a synthetic resin 14 as described above. In this case as well, as in FIG. 4, the sheet exhibits conductivity in the thickness direction and electrical insulation in the sheet surface direction. When the element body 9 on which no electrode is formed is tightly enclosed in such an anisotropic conductive sheet and sealed, the element body 9 is sealed and at the same time, the electrode can be taken out from an appropriate part on the sheet surface. can. Therefore, since the anisotropically conductive sheet is completely electrically insulating in the plane direction and electrically conductive only in the thickness direction, the element body 9 can be contained in this sheet alone. As shown in FIG. 3, it is also possible to interpose electrically insulating packings 6, 8,
The negative electrode layers and positive electrode layers 7', 10, and 11 are not required again. Therefore, the structure of the electronic device is simplified, which is particularly effective in making it smaller and thinner. In addition, since the sealing part of an electronic device is made of the same material as the anisotropically conductive sheets, for example, the sealing part is dissolved with a solvent that dissolves the synthetic resin of the anisotropically conductive sheet, and then the sealing part is sealed under pressure, and the solvent is evaporated. The sealing method is relatively simple, such as thermally melting and pressure welding, or sealing with adhesive, and the sealing performance of the sealing part is also extremely good compared to conventional methods. becomes.

Furthermore, in the present invention, since the element body without the electrode part formed thereon can be used as is, the process of forming the external electrode material and the electrode part of the element body can be omitted, and the size and thickness can be reduced by the thickness of the electrode layer. I can do it. Additionally, if an anisotropically conductive sheet with a wide area is used, a large number of elements can be placed on the surface of this sheet, and an even wider sheet can be placed on top of the element to seal the periphery of the element at once. Thus, a manufacturing method is obtained in which a large number of electronic devices can be sealed and external electrodes can be formed at the same time.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Example 1 A sheet of lithium metal was cut into disks with a diameter of 30 mm and a thickness of 0.3 mm under an argon gas atmosphere. This lithium metal disk is used as the negative electrode active material 1 of the battery, and the disk has a diameter of 31 mm and a thickness of 31 mm.
An electrolyte layer 2 made of a 100 μm polypropylene nonwoven fabric is placed on top of the electrolyte layer 2, and a mixed powder of 95% by weight of manganese dioxide powder and 5% by weight of carbon black powder is pressure molded to form a disk shape with a diameter of 30 mm and a thickness of 0.3 mm. A battery element body 9 was obtained by placing the positive electrode active material 3 formed thereon. Figure 6a shows the battery element body 9 obtained as described above.As shown in Figure 4, thin stainless steel wires 13 with a diameter of 30 μm are embedded in a polyethylene synthetic resin 14 at intervals of 0.1 mm. Anisotropically conductive sheets 16 and 16' having a thickness of 0.3 mm are cut into disc-shaped sheets having diameters of 36 mm and 35 mm, respectively, and these are brought into close contact with the upper and lower surfaces of the element body 9 as shown in FIG. 6b.
This was placed on a Teflon plate (not shown) and pressurized with a cylindrical press jig (not shown) with an inner diameter of 31 mm and an outer diameter of 40 mm (not shown), which had been heated in advance to the melting point of polyethylene at a temperature of 150°C or higher. The peripheral parts 16a and 16b of the anisotropically conductive sheet covering the side circumference of the element body 9 are fused together to form the peripheral part 1 of the anisotropically conductive sheet.
It was sealed with 6a and 16b. FIGS. 6c and 6d are a perspective view and a sectional view, respectively, of the battery obtained as described above. Anisotropic conductive sheet 16
In this case, the sealing portion 18 of a, 16b is the element body 9
It is located on the layer side of the positive electrode active material 3 on the lower surface of. A diameter of 30mm is placed on the top and bottom surfaces of the battery thus obtained.
When a metal disk of mm or larger was placed on it and measured with a voltmeter, it showed an initial electromotive force of 3.5V, and when the current at the time of a short circuit was measured with an ammeter, it showed a large current value of 100mA, which is sufficient for a battery. Turns out it works. Further, even when this battery was left in high humidity for a long time, no moisture was observed to enter the battery, and it exhibited very good sealing performance.

Example 2 Barium titanate-based dielectric material powder was press-molded and sintered at high temperature to form a dielectric element body 17 with a diameter of 10 mm and a thickness of 0.5 mm.
0.2 mm anisotropic conductive sheet 16 similar to Example 1
and 16' are closely connected, and this is 10.5 mm in diameter and 10.5 mm in depth.
Place it on a Teflon plate (not shown) in which a 0.25 mm groove has been dug, and place a cylinder (15 mm in outer diameter) heated above the melting point of polyethylene ( (not shown).

FIG. 7 is a sectional view of the capacitor thus obtained. A dielectric element body 17 is sealed with anisotropic conductive sheets 16 and 16'. In this case, the sealing portion 18 of the peripheral portions 16a and 16b of the anisotropic conductive sheet is located at the center in the thickness direction of the capacitor or element, and the sealing portion 18 of the anisotropic conductive sheet is located at the center of the capacitor or element in the thickness direction.
It is different from the shape in which 8 is tilted to one side. Metal disks with a diameter of 10 mm or more were closely placed on the upper and lower surfaces of this capacitor, and capacitor characteristics such as capacitance value and dielectric loss rate tan δ were measured at a frequency of 1 kHz. and 1
It almost matched the capacitor characteristic value before inclusion in 6'. Furthermore, in a humidity test in which this capacitor was left in a high-humidity atmosphere for a long time, the characteristics of the capacitor remained the same as before being left in a humid environment.

Even if the dielectric element body 17 is enclosed in the anisotropically conductive sheets 16 and 16' as in this embodiment, the effect of the present invention, that is, the electrode can be taken out and sealed sufficiently with a simple enclosing means. It turns out that it can be obtained.

Example 3 FIG. 8 shows a vertical 10-layer structure made of the same negative electrode active material 1, electrolyte layer 2, and positive electrode active material 3 as in Example 1.
The upper and lower surfaces of the battery element body 9, which is 40 mm wide and 0.7 mm thick, are closely connected with anisotropic conductive sheets 16 and 16' that are 12 mm long, 42 mm wide, and 0.2 mm thick, and then covered with a Teflon plate. (Illustration omitted) Place it vertically from the top.
It was sealed by heating and pressurizing it with a square prism jig (not shown) in which a rectangular parallelepiped groove of 10.5 mm, width 40.5 mm, and depth 3 mm was dug. The anisotropically conductive sheet used at this time had a structure in which approximately 10 μm nickel powder particles 15 were connected to a synthetic resin 14 made of a polybutadiene rubber elastic body, as shown in FIG. belongs to. For sealing, unvulcanized polybutadiene is sufficiently applied to the upper and lower surfaces of the anisotropically conductive sheets 16 and 16' made of polybutadiene to be sealed, and this is heated and pressurized using the above-mentioned method. I did it. When heated, the anisotropically conductive sheets 16 and 16' are completely bonded together by the unvulcanized polybutadiene.

The battery obtained by the above method is sandwiched between metal plates with a length of 10 mm or more and a width of 40 mm or more, and the load resistance is
As a result of measuring the battery characteristics with 1KΩ connected, the voltage was
It was confirmed that it functions well as a 3.0V battery. Furthermore, the sealing properties were examined from the self-discharge rate and were found to be extremely good.

As in this example, the shape of the element body is a rectangular parallelepiped,
It was also understood that the effects of the present invention can be sufficiently obtained even when an anisotropically conductive sheet having a structure as shown in FIG. 5 is used, and even when an unvulcanized polybutadiene adhesive is used for sealing.

Example 4 FIG. 9 is a top view of a total of 12 battery element bodies 9 obtained by the same method as in Example 1. First, the vertical 118 cm was placed on a Teflon plate (not shown).
Place the same anisotropic conductive sheet as in Example 1, measuring 155 mm wide, and place the element body 9 on this sheet 3 times vertically.
4 pieces horizontally, each arranged in an array with a spacing of 7.0 mm. Next, a total of 12 cylindrical grooves with a diameter of 30.3 mm and a depth of 3 mm, 3 vertically and 4 horizontally, were dug with the same dimensions as the arrangement of the element body 9.
10mm heated rectangular metal jig (not shown)
The element body 9 was heated and pressurized from above. After the sealing parts 18 of the anisotropic conductive sheets 16 and 16' are sufficiently fused, the rectangular parallelepiped metal jig is attached to the element body 9.
Then, each battery was punched out using a cutter with a diameter of 32 mm to obtain 12 batteries sealed with an anisotropically conductive sheet. This battery characteristic has a load resistance of 10kΩ
When measured, it showed an electromotive force of 3V for a long time. In addition, all sealing properties were good.

As described above, the present invention has a great effect in that small and thin electronic devices can be mass-produced at the same time as the exterior sealing and the electrode portion removal.

Note that the present invention is not limited to the batteries and capacitors described in the embodiments, but can also be applied to other general electronic devices such as semiconductors and resistors. Furthermore, it goes without saying that the shape of the electronic element may be a disk shape, a rectangular parallelepiped, or the like other than the shape of this example, if necessary.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional button-shaped or coin-shaped battery, Figures 2 and 3 are cross-sectional views of a conventional sheet battery, and Figures 4 and 5 are anisotropic conductive sheets used in the present invention. FIG. Fig. 6 is an assembled view of a battery according to an embodiment of the present invention, Fig. 6a is a perspective view of a battery element body, and Fig. 6b is an assembled view of an anisotropic conductive sheet and a battery element body. A perspective view of
FIG. 6c is a perspective view of the battery after the element body is sealed, and FIG. 6d is a sectional view of FIG. 6c. FIG. 7 is a sectional view of a capacitor according to another embodiment of the present invention, and FIG. 8 is a perspective view after sealing of a battery according to an embodiment of the present invention in which the battery shape is formed into a rectangular parallelepiped. FIG. 9 is a top view of a mass-produced battery in which the battery of the present invention is formed into a disk shape. 1... Negative electrode active material, 2... Electrolyte layer, 3... Positive electrode active material, 4... Lid (made of negative electrode metal), 5...
Case (made of positive electrode metal), 6, 8... (electrically insulating) packing, 7, 7', 10, 11... metal foil, 9... (battery) element body, 12, 12'...
...electrical insulating film, 13... (conductive) thin wire, 14... synthetic resin, 15... (conductive) particles, 16, 16'... anisotropic conductive sheet, 17...
...(Dielectric) element body, 18... (Anisotropic conductive sheets 16a, 16b) Sealing portion, 16a, 16b
...Peripheral area of the anisotropic conductive sheet.

Claims (1)

[Claims] 1. An element body such as a semiconductor, a resistor, a dielectric, a battery, etc. in which no electrode portion is formed is an anisotropically conductive sheet having conductivity in the thickness direction and electrical insulation in the plane direction. An electronic device characterized in that external electrodes are formed by tightly encapsulating the device body and sealing the entire periphery of the device body. 2. Element bodies such as semiconductors, resistors, dielectrics, and batteries on which electrode parts are not formed are sandwiched between two anisotropically conductive sheets that are conductive in the thickness direction and electrically insulating in the surface direction. A method for manufacturing an electronic device, characterized in that the sheet on the periphery of the device body is then sealed.