JPS61106474A - Method of releasing melt-bonded portion of ceramic film burnt matter - 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] [Industrial Application Field] When manufacturing ceramic capacitors, etc., a fired product in the form of a thin ceramic film or sheet (hereinafter collectively referred to as "film") is used. used. In order to produce such a fired ceramic product, a large number of thin green sheets are fired simultaneously, but the sheets that are in contact with each other may sometimes weld together. The welded portion is peeled off later, and those that cannot be peeled off are discarded.The present invention relates to a method for peeling off the welded portion when firing ceramics.

[Conventional technology]

With the recent rapid trend toward ICs, there is a strong demand for smaller parts and chips in the field of ceramic capacitors, and as circuits become more complex, the number of capacitors used is increasing. . Under these circumstances, ceramic capacitors have responded to needs such as smaller size, stability, high frequency characteristics, and diversification of temperature characteristics, and trends such as the development of new ceramic dielectric materials and thinner dielectric layers are progressing. ing. Furthermore, in terms of manufacturing, in order to reduce costs and ensure high quality by improving yield,
Quality control in each manufacturing process is becoming increasingly important.

FIG. 2 shows the manufacturing process of ceramic capacitors that is currently commonly used. The dry method is a manufacturing method used for high-pressure condensers and products with relatively low production volumes.In Japan, the soft method using a vacuum extruder is common, so we will explain the manufacturing process using the soft method below. . - Synthetic ceramic dielectric materials mainly composed of titanium barium, which is the main raw material for ceramic capacitors, are made by adding a water-based binder mainly composed of Metrose and glycerin to ensure that they are sufficiently cross-wired in the kneading process a.
Stirred.

Further, the green sheet is formed into a green sheet with a thickness of about 0.1 m by vacuum extrusion@b, and then punched into a predetermined size by a punching machine C. Before entering the next firing step d, these molded products are stacked in several rows on a flat plate of a box, which is a heat-resistant ceramic container.

The molded product stored in the box is then heated in an electric or gas furnace in the firing step d (the temperature is adjusted to 850 to 1400'C, depending on the firing conditions of the raw materials).
It is fired for several tens of hours.

Baking of silver paste or plating with nickel, silver, gold, etc. on the fired product made into porcelain is done in step e, and the lead wire is attached in step f for lead wire processing, and insulated in step g for exterior packaging. After being painted and subjected to moisture-proofing, it is shipped as a finished product after inspection.

Having explained the method for manufacturing ceramic capacitors above,
It goes without saying that in order to manufacture high-quality ceramic capacitors with good yields, strict control and checks are carried out in all aspects of the process, including the preparation of raw material powder.

[Problem that the invention seeks to solve]

Here, when the above-mentioned molded products are fired continuously, it is common to stack a plurality of molded products immediately and transport them in a stacked state. The reason for this is to increase the rotation rate of the firing furnace, which requires firing over a long period of time as mentioned above, or to improve production efficiency. This is because it becomes very long and very uneconomical.

However, when raw molded products are collected and fired in this way,
Since welding may occur at the contact areas of molded products, the number of sheets stacked is reduced or adhesion prevention powder is applied to prevent molded products from deforming and welding during firing. For this reason, production efficiency cannot always be said to be sufficient.Moreover, even with these considerations, the baking process, which takes several tens of hours in a high-temperature atmosphere, does not completely prevent welding between stacked films. It is difficult to get rid of it. Therefore, it is necessary to manually peel off the welded parts one by one afterward, and some products may be disposed of as defective.
Problems also remain in terms of yield improvement.

The technical problem of the present invention is to make it possible to reliably, easily, and efficiently peel off the welded portions of ceramic films that occur when they are stacked and fired in a ceramic firing furnace.

[Means for solving problems]

In order to achieve this objective, the present invention is directed to a fired product made by stacking several or more sheets or films of ceramic thin raw raw materials, in which welded parts are formed at the contact surfaces of the ceramic films. When peeling off the integrated ceramic film, a method is adopted in which the temperature of the integrated ceramic film is raised to a temperature of 100 to several 100° C. and then immediately cooled, and the welded portion is separated by applying a thermal shock. Rapid cooling is done by placing it in an aquarium or pouring water over it.

[Effect]

That is, according to the method of the present invention, the fired product of the welded ceramic film is heated to a temperature of 100 to several 100° C. in a heating tank such as an electric heater, a hot air tank using gas as a heat source, an infrared heater, or an electric heater. Immediately spray the area with water or place it in water to cool it down quickly.

Then, thermal strain and thermal shock occur on the welded surfaces between the respective ceramic films, which causes the welded portions to easily peel off. In this case, it has been found that it is desirable that the temperature distribution to be heated be as uniform as possible to the center, and that it is desirable to cool rapidly.

For this purpose, dielectric heating using microwaves, an internal heat generation method using molecular vibration, can achieve more uniform heating and easier temperature adjustment than heating by heat conduction using general heat sources such as electric heat or gas. It is an effective heating means.

As a subsequent cooling method, it was found that dropping or immersing in water is an inexpensive method that not only provides a high cooling rate.

〔Example〕

Next, an embodiment of a method for peeling off a ceramic welded part by thermal shock according to the present invention will be described. FIG. 1 is a longitudinal cross-sectional view showing a peeling apparatus for carrying out the method of the present invention using microwave heating.

A belt conveyor 3 is provided between a hopper 2 for supplying the welded ceramic film fired product 1 and a cooling water tank 13 for rapid cooling. This belt conveyor 3 is guided by front and rear pulleys 10.11 and is driven by a motor 12.

A micro liquid heating open furnace 4 is disposed at an intermediate position of the belt conveyor 3, and a microwave oscillator 6 is connected via a waveguide 5.

Radio wave leakage prevention devices 9a and 9b are installed at the inlet and outlet of the micro-liquid heating open furnace 4. microphone.

An electric heater 7 is installed in the microwave heating open furnace 4 as required.
A hot air generator combining a blower 8 and a blower 8 is installed to blow hot air.

The cooling water tank 13 is a place where the heated fired ceramic is rapidly cooled, and the water supply pulp 14 and the overflow drain pipe 1 are connected to the cooling water tank 13.
5 is provided. Further, a conveyor 16 is disposed diagonally in the cooling water tank 13 for taking out the ceramic that has fallen into the cooling water tank 13 and peeled off to the outside of the tank. The lower end of this take-out conveyor 16 is located directly below the terminal end of the belt conveyor 3.

Next, the operation of the peeling process using this apparatus will be explained.

First, when a fixed amount of the welded ceramic fired product 1 is put into the hopper 2, the fired product is supplied from the hopper 2 onto the belt conveyor 3 in a fixed amount of thickness. Then, it passes through the radio wave leakage prevention taOa on the entrance side on conveyor 3,
The micro liquid is transferred to the heating oven furnace 4, then passes through the exit side radio wave leakage prevention device 9b, and is sent to the cooling tank 13.

When passing through the micro liquid heating oven furnace 4, the fired ceramic product 1 is irradiated with microwaves, and the temperature of the fired ceramic product 1 is raised to 100 to several 100° C. by the microwave energy. The microwave energy given here is
Unit internal volume in heating oven furnace 0.01 to 0.0 per light
It is desirable to irradiate at a density of 2W/cm or less; if more energy is applied, dielectric breakdown occurs at the contact surfaces between ceramic films or between stacked ceramics, resulting in electrical discharge or damage. , it becomes difficult to obtain preferable heating.It has been found that if the heating conditions in the micro-liquid heating oven are carried out under the above conditions, it is possible to obtain a good uniform heating state without causing discharge or destruction.

Now, the baked product 1 whose temperature has been continuously raised in the micro liquid heating open furnace 4 falls one after another into a water tank 13 in which cooling water is stored.
There, the welded part is immediately subjected to thermal shock due to rapid cooling, and the welded part is peeled off. The heated ceramic fired product falls from the conveyor 3 onto the take-out conveyor 16 in the cooling water tank 13, so the ceramic fired product after cooling falls onto the take-out conveyor 16.
As a result, they are discharged out of the tank one after another. In addition, in order to maintain the water temperature in the cooling water tank within a range that does not impede the rapid cooling effect, cooling water is supplied from the water supply pulp 14, and the water in the water tank whose temperature has risen is allowed to overflow from the drain pipe 15. , temperature regulated.

〔Effect of the invention〕

As described above, according to the present invention, the welded part when firing several or more thin ceramic raw raw materials in the form of sheets or films is heated by the temperature of the ceramic film.
After raising the temperature to 100 to several 100 degrees Celsius, it is immediately rapidly cooled and separated by thermal shock. By applying thermal shock in this manner, the welded portions between the ceramic films can be easily and reliably peeled off, making it possible to simultaneously perform firing treatment on a large amount of ceramic films. Furthermore, since the material is rapidly heated using microwave heating and rapidly cooled with water, the processing time required for peeling is extremely short, and only a temperature change is required, which greatly improves production efficiency.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an apparatus for carrying out the method for peeling off welding of a fired ceramic film according to the present invention, and FIG. 2 is a block diagram showing the manufacturing process of a conventional ceramic capacitor. In the figure, ■ indicates a fired ceramic (film) product, 3 indicates a conveyor, 4 indicates a microwave heating oven, 13 indicates a cooling water tank, and 16 indicates a take-out conveyor. Patent applicant: Microelectronics Co., Ltd. Agent Patent attorney: Yasushi Fukushima Figure 1

Claims (2)

[Claims] (1) When peeling off the welded parts at the contact surfaces of the ceramic films in a fired product made by stacking several or more sheets or films of ceramic thin raw raw materials, the integrated ceramic film 1. A method for peeling a welded part of a fired ceramic film, the method comprising raising the temperature to 100 to several hundreds of degrees Celsius, immediately cooling the welded part immediately, and applying a thermal shock to separate the welded part. (2) Microwave dielectric heating at 2450±25 MHz is used as a means to raise the temperature of the ceramic film welded by the firing described above, and in this case, the microwave heating irradiation output density is set to the unit internal volume of the microwave irradiation oven. irradiation with an intensity of 0.01 to 0.02 W/cm^3 or less, and the temperature of the integrated ceramic film is 100 to 30%.
A method for peeling off a welded portion of a fired ceramic film according to claim (1), wherein the welded film is peeled off by raising the temperature to a range of 0°C and then immediately quenching with water.