KR102025609B1 - Gas oven for manufacturing electronic component - Google Patents

Abstract

The present invention relates to a gas oven for manufacturing an electronic component, which is provided to maintain the pressure in a main body to be suitable for a process, while adequately controlling the oxygen concentration in the main body. To this end, the present gas oven comprises: a main body (10); a heating body (11); a blowing fan (12); an air suction hole (13); and an air ventilation hole (14).

Description

Gas oven for electronic component manufacturing {GAS OVEN FOR MANUFACTURING ELECTRONIC COMPONENT}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas oven for electronic component manufacturing that performs a binder removal plasticization step of a ceramic capacitor. More specifically, the binder removal plasticization step of a ceramic capacitor can be performed in a nitrogen atmosphere as well as air depending on the product process. The present invention relates to a gas oven for manufacturing electronic components.

Generally, as a raw material for semiconductor ceramics such as ceramic capacitors including multilayer capacitors, high voltage capacitors, piezoelectric ceramics, microwave dielectrics, semiconductor capacitors, PTC thermistors, NTC thermistors, ceramic sensors, and the like, barium titanate (BaTiO ₃ ), Oxides such as lead zirconate titanate (PbZrTiO ₃ ), zinc oxide (ZnO), zirconium oxide (ZrO ₂ ), rare earth oxides, glass materials, aluminum oxide, silicon oxide, or composites thereof are used.
The ceramic electronic component is manufactured into a molded body by molding a ceramic raw material into a predetermined shape, and then the multilayer ceramic capacitor is completed by sequentially performing a binder removal process in an oven, a firing process in a kiln, and a cooling process.
In the process of manufacturing such a ceramic capacitor, a slurry is prepared by adding a binder, which is an organic component, to raw material powders such as BaTiO 3, CaCa 3, MnO, and Glass Frit, and a ceramic sheet is formed using the slurry as a dielectric sheet. The laminated sheet is manufactured by laminating a plurality of ceramic sheets printed with the internal electrodes on a surface of the ceramic sheet by pattern printing internal electrodes, which are metal components of Ni, Cu, Pd, and Pd / Ag, in the multilayered sheet. After pressing at a pressure of 500 to 1300 kgf / cm 2, a rectangular parallelepiped ceramic capacitor is manufactured by cutting the compressed laminated sheet to a predetermined length.
In addition, the ceramic capacitor is baked in a oven at a temperature of 230 ~ 350 ℃ (bake-out) to remove the binder component, a firing process for baking for 10 to 24 hours at a temperature of 900 ~ 1300 ℃, and After the completion of the firing, a cooling process of cooling to a low temperature is continuously performed, and the ceramic capacitor fired in the firing furnace is completed by the plating process by coating an external electrode and a terminal electrode on the outer circumferential surface thereof.
Here, the binder used for laminating a ceramic capacitor composed of a binder of an organic component, an internal electrode of a metal component, and a ceramic sheet of a ceramic component is effectively removed in a calcination process, which is a debinder process, thereby making inconsistencies in the ceramic molded body having different heterogeneous characteristics. Preventing delamination or cracking defects, which may be caused by mismatching, is an important process variable that controls the quality characteristics of ceramic moldings.
The conventional ceramic oven to which such a process is applied is as shown in Figure 1 shown, based on this look at the basic structure as follows.
1 is a perspective view showing a conventional oven, the conventional oven 100 is composed of a box-shaped body 120 is coupled to the door 110 is openly coupled to the front, the inside of the body 120 is multi-stage The product loading space 121, which is divided into a plurality of ceramic capacitors C, is provided.
The main body 120 is provided with an inlet 122 through which external air flows into one side thereof, and an exhaust port 123 is mounted on the other side or the same side thereof, and both side walls of the inner side are provided with a plurality of through holes. 124 is provided.
In addition, the main body 120 has a fan 125 for supplying the outside air introduced from the suction port 122 to the inside of the loading space 121, the one side of the fan 125 is introduced The heater 126 which heats external air is provided.
Such a conventional oven 100 is heated by the air introduced into the interior of the main body 120 through the inlet 122 through the heater 126 is loaded through the perforated plate 124 of each side of the main body 120 It is a direct hot air circulation system supplied into the space.
That is, the hot air introduced into the main body 120 through the one side perforated plate 124 while passing through the heater 126 on the upper part of the main body 120 is a ceramic capacitor stacked in the upper, middle and lower product loading space 121 ( C) is removed to remove the organic binder in the ceramic capacitor C, and then discharged to the outside through the perforated plate 124 and the exhaust port 123 on the other side of the main body 120.
(Prior art document)
(Patent Document 0001) Republic of Korea Patent Publication No. 10-0237292 (registered on October 7, 1999)
(Patent Document 0002) Republic of Korea Patent Publication No. 10-0404739 (2003.10.27 registered)
(Patent Document 0003) Republic of Korea Patent Publication No. 10-0826268 (registered April 23, 2008)
(Patent Document 0004) Republic of Korea Patent Publication No. 10-1075986 (2011.10.17.Registration)

However, since the heat source is supplied to the ceramic condenser C in a hot air convection method through the fan 125 on the top of the main body 120, the conventional oven 100 has a point close to the perforated plate 124 that is a hot air supply unit. Although hot air is supplied, hot air of a relatively low temperature is inevitably supplied to the perforated plate 124 and the exhaust port 123 at a long distance, and thus a large temperature deviation is generated in the main body 120. Cracks caused by mismatching of ceramic components and metal components contained in the ceramic capacitor were generated due to the applied firing temperature variation.
In addition, as the binder removal process is performed in a short time (about 22 to 24 hours) in the air, the reaction pressure is increased due to excessive air supply, and the ceramic capacitor is oxidized or bursting occurs.
The present invention has been made to solve such a problem in the prior art, and by improving its structure, it is possible to stably supply moisture-containing nitrogen (N ₂ ) to the gas oven to miniaturized and highly integrated electronic components The purpose is to enable the binder removal process of the ceramic capacitor used.
Another object of the present invention is to automatically adjust the discharge of the exhaust gas in the process of performing the binder removal process of the ceramic capacitor to maintain the pressure in the body according to the process.
Still another object of the present invention is to control the oxygen concentration in the main body properly by adjusting the supply amount of nitrogen according to the progress of the process.

According to an aspect of the present invention for achieving the above object, a heating element installed in the main body, the heating element for raising the internal temperature, and a blowing fan installed on one side of the heating element to circulate oxygen and nitrogen introduced into the main body; A gas oven for connecting to one side of the main body and having an inlet for oxygen and nitrogen to be introduced into the main body, and an exhaust port connected to the main body for circulating the inside of the main body to discharge exhaust gas to the outside A first valve installed in the first nitrogen supply line and supplying the amount of nitrogen set by the first flow meta to the second nitrogen supply line through the first connecting pipe, and installed in the first nitrogen supply line A second valve installed at a rear end of the first valve and supplying the amount of nitrogen set by the second flow meta to the second nitrogen supply line through the second connecting pipe; A wet tank installed in the air supply line to convert nitrogen supplied to the water-containing nitrogen, a supply pipe connected between the inlet port and the wet tank to supply the nitrogen containing water to the inside of the main body through the inlet port, and Pressure adjusting means installed in the exhaust pipe connected to the exhaust port to automatically adjust the pressure in the main body, exhaust gas exhaust amount adjusting means installed in the exhaust pipe to adjust the exhaust amount of the exhaust gas, the heating element, blowing fan, pressure adjusting means, exhaust And a control unit for controlling the driving of the gas displacement adjusting means, and connecting a third nitrogen supply line between the second nitrogen supply line and the supply pipe to supply dry nitrogen to the inside of the main body through the second nitrogen supply line. The first and second control ball valves are installed at the front and rear ends of the wet tank, and the third control ball valve is provided at the third nitrogen supply line. There is provided a gas oven for producing electronic components, characterized in that by installing the.

The present invention has several advantages over the prior art.
First, according to the plasticizing process of the ceramic molded body (particularly, ceramic capacitor) to be produced, the binder removal plasticizing process of the ceramic molded body can be carried out while supplying air as well as nitrogen or dry nitrogen containing moisture into the main body of the product. The defective rate can be significantly reduced.
Second, since the oxygen concentration in the main body can be kept constant at all times according to the process of calcination of the ceramic molded body, oxidation of the ceramic molded body is prevented or bursting phenomenon is prevented.
Third, as well as a plurality of valves to supply nitrogen to the nitrogen tank to the nitrogen supply line, as well as a reserve for supplying nitrogen to the wet tank automatically open even if the valve cannot be controlled due to sudden power failure. The valve is provided to prevent the failure of the power failure in advance.

1 is a perspective view showing a conventional oven
2 is a block diagram showing the present invention
Figure 3 is a perspective view of the oven of the present invention
Figure 4 is a perspective view of the pressure adjusting means and the exhaust gas amount adjusting means of the present invention

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. It is noted that the figures are schematic and not drawn to scale. The relative dimensions and ratios of the parts in the figures have been exaggerated or reduced in size for clarity and convenience in the figures and any dimensions are merely exemplary and not limiting. And the same reference numerals are used to refer to similar features in the same structure, element or part shown in more than one figure.
2 is a schematic view showing the present invention, Figure 3 is a perspective view of the oven of the present invention, Figure 4 is a perspective view showing the pressure regulating means and the exhaust gas emission control means of the present invention, the present invention is the interior of the body 10 The heating element 11 for raising the internal temperature is installed in one side, and one side of the heating element 11 is provided with a blowing fan 12 for circulating oxygen and nitrogen introduced into the main body 10, the main body 10 In the air inlet 13 for allowing oxygen and nitrogen to enter the inside of the main body 10 and the exhaust port 14 for discharging the exhaust gas circulated inside the main body 10 is provided, this configuration is a conventional gas oven Is the same as
In the gas oven having such a configuration, the present invention provides a first nitrogen supply in which nitrogen is supplied to stably supply moisture-containing nitrogen to the inside of the main body 10 so that the binder removal plasticization process of the ceramic molded body (condenser) can be performed. A first valve 23 is provided in the line 20 to supply the amount of nitrogen set by the first flow meta 21 to the second nitrogen supply line 30 through the first connecting pipe 22. At the rear end of the first valve 23 installed in the first nitrogen supply line 20, the amount of nitrogen set by the second flow meta 24 is transferred to the second nitrogen supply line through the second connecting pipe 25. The 2nd valve 26 supplied to 30 is provided.
The reason why the first and second valves 23 and 26 are installed in the first nitrogen supply line 20 is that the main body 10 is formed through the first valve 23 in the initial rising section of the ceramic formed body which performs the calcination process. In the case of supplying a large amount of nitrogen to the holding section while supplying a value set in the inside of the is to supply a large amount of nitrogen through the first valve 23 and the second valve (26).
A second nitrogen supply line 30 is connected to a rear end of the first and second flow meta 21 and 24, and the nitrogen supplied to the end of the second nitrogen supply line 30 is nitrogen containing moisture. A converting wet tank 31 is provided, and the structure of the wet tank 31 is described in detail in Utility Model No. 444706 (registered on May 25, 2009) registered in advance by the applicant. The description of the structure and operation thereof is omitted.
A supply pipe 32 is connected between the intake port 13 and the wet tank 31 to supply the moisture-containing nitrogen to the inside of the main body 10 through the intake port 13, and is connected to the exhaust port 14. The exhaust pipe 41 is provided with a pressure regulating means 40 for automatically adjusting the pressure in the main body 10.
In the embodiment of the present invention, the pressure adjusting means 40 is connected to the exhaust port 14 as shown in FIGS. 2 and 3, and the main exhaust pipe 41a through which the exhaust gas is discharged by the operation of the manual valve 42. And a first proportional control valve 43 installed on the first exhaust pipe 41b communicating between the upper and lower portions of the manual valve 42 to adjust the displacement by the pressure in the main body 10; Installed on the second exhaust pipe 41c communicating between the upper and lower parts of the manual valve 42 to quickly discharge the exhaust gas in the main body 10 in the cooling section of the ceramic capacitor, or the pressure in the main body during the process is greater than or equal to the set value. It consists of an exhaust valve 44 which discharges exhaust gas at the time.
The present invention is provided with an exhaust gas exhaust amount adjusting means 50 for adjusting the exhaust amount of the exhaust gas in the exhaust pipe 41 in addition to the pressure adjusting means 40.
In the exemplary embodiment of the present invention, the exhaust gas exhaust amount adjusting means 50 is installed at an upper portion of the exhaust pipe 41 connected to the exhaust port 14 to adjust the exhaust gas exhaust amount. And a pair of cylinders 53 connected to the damper 51 by a connecting bar 52 to move the damper 51 up and down, and the first nitrogen supply line 20 to nitrogen. Is provided with a third connecting pipe (54) for supplying the gas to the cylinder (53) side to drive the cylinder (53), and a solenoid valve (55) installed on the third connecting pipe (54) to open and close the flow path. .
In addition, in the present invention, the third nitrogen supply line 60 supplies a second nitrogen supply line to supply not only moisture containing nitrogen through the second nitrogen supply line 30, but also dry nitrogen into the body 10. It is connected between the 30 and the supply pipe 32, and the first and second control ball valves 61 and 62 are installed at the front and rear ends of the wet tank 31, and the third nitrogen supply line 60 The 3rd control ball valve 63 is provided, and the 1st, 2nd, 3rd control ball valve 61, 62, 63 is comprised so that the supply flow path of nitrogen may be changed.
The present invention stably supplies nitrogen to the inside of the main body 10 through the first, second and third nitrogen supply lines 61, 62 and 63 by opening the first and second valves 23 and 26. First and second preliminary valves 27 and 28 to stably supply nitrogen even when the first and second valves 23 and 26 are turned off due to sudden power failure while performing the binder removal plasticization process of the ceramic molded body. Is further provided.
That is, the first and second branch pipes 33 and 34 are connected between the first nitrogen supply line 20 and the first and second connection pipes 22 and 25, and the first and second minutes are connected. The engines 33 and 34 automatically open when the first and second valves 23 and 26 are turned off in the process of supplying nitrogen to the inside of the main body 10, and the first and second minutes are automatically opened. First and second spare valves 27 and 28 are provided to automatically open the flow paths of the engines 33 and 34.
The driving of the heating element 11, the blowing fan 12, the pressure regulating means 40, the exhaust gas exhaust amount adjusting means 50 is configured to be controlled by the control unit 70.
Since the shaft 15a of the motor 15, which is the driving source of the blower fan 12, is supported by the bearing and the packing 16 to rotate, the air does not enter the inside of the main body 10 by a gap therebetween. It is more preferable to seal.
To this end, according to the present invention, as the process gas uses nitrogen, a fourth connecting pipe 17 is installed in the airtight holding part of the first nitrogen supply line 20 and the motor shaft 15a, and the fourth connecting pipe ( The pressure regulator 18 and the 4th flow meta 19 are provided in 17).
On the other hand, in the present invention, the air supply line 80 is connected to the second nitrogen supply line 30 to supply air as necessary as well as nitrogen in the main body 10 in the binder removal plasticization process of the ceramic molded body In the air supply line 80, a ball valve 81, a pressure regulator 82, a third valve 83, and a third flow meter 84 are sequentially installed.
In the present invention configured as described above, a debinder calcination process of a compact and highly integrated multilayer ceramic capacitor will be described as follows.
First, in a state in which a ceramic capacitor (not shown) to be subjected to a calcination process is formed and placed in a setter, nitrogen supplied through the first nitrogen supply line 20 is supplied to the first valve 23 in an initial rising section. And the first flow meta (21) is moved to the second nitrogen supply line (30) and then converted into the water-containing nitrogen in the water tank (31) and then supplied to the body (10) through the inlet (13) Therefore, a calcination process is performed, at which time the second valve 26 is closed.
In this state, when the inside of the main body 10 reaches the keep section through the rising section, the control unit 70 opens the second valve 26 so that a larger amount of nitrogen is introduced into the main body 10. Since it is supplied to the sintering process is performed stably.
As described above, when performing the calcination process using nitrogen containing moisture, the first and second controls provided in the second nitrogen supply line 30 and the supply pipe 32 located at the front and rear ends of the wet tank 31. Since the ball valves 61 and 62 are open and the third control ball valve 63 installed in the third nitrogen supply line 60 is closed, the nitrogen supplied to the second nitrogen supply line 30 is supplied to the wet tank ( 31) is supplied to the side is converted to the nitrogen containing moisture and then supplied to the inside of the main body 10 through the supply pipe (32).
As such, when the nitrogen-containing water is supplied to the main body 10 to perform the calcining process, the oxygen concentration is maintained at 50 ppm or less so that the oxidation is not performed. This is to prevent the condenser from oxidizing or bursting due to a pressure rise due to a sudden reaction.
That is, the present invention, when removing the carbon component contained in the ceramic capacitor by the nitrogen containing moisture introduced into the main body 10, the manual valve installed in the main exhaust pipe 41a, which is a pressure regulating means (open) 42, the opening and closing amount of the first proportional control valve 43 installed in the first exhaust pipe 41b is automatically adjusted in the process of exhausting a certain amount of exhaust gas to the main exhaust pipe 41a, so that the pressure in the main body 10 is reduced. According to the process, the oxygen concentration in the main body 10 can be arbitrarily set and maintained below the set value.
In the process described above, the oxygen concentration in the main body 10 has a concentration suitable for the characteristics of the product, and when the oxygen concentration is lowered, a large amount of nitrogen is required, which acts as a cause of an increase in production cost, and thus, generally, it is managed at 50 ppm or less Doing.
When the nitrogen is supplied to the cylinder 53 by operating the solenoid valve 55 installed in the third connecting pipe 54 during the process as described above, the position of the damper 51 fixed by the connecting bar 52 is adjusted. It has the advantage of more finely controlling the emissions of the exhaust gas.
However, if the exhaust gas in the main body 10 is discharged quickly in the cooling section after the holding section is finished during the calcination process, or if the internal pressure of the main body 10 rises above the set value during the calcination process (rising section and the holding section), the second pressure is increased. Since the exhaust valve 44 installed in the exhaust pipe 41c is opened to discharge the exhaust gas to the outside, defects of the ceramic capacitor can be prevented in advance, and the time according to the calcination process can be reduced.
Hereinafter, a process of plasticizing a ceramic molded body by supplying dry nitrogen to the inside of the main body 10 will be described.
The process of supplying nitrogen to the second nitrogen supply line 30 through the first nitrogen supply line 20 and the first and second valves 23 and 26 is the same as described above.
However, only the state in which the 1st, 2nd control ball valve 61 and 62 provided in the front and rear ends of the wet tank 31 is closed, and the 3rd control ball valve 63 provided in the supply pipe 32 is opened is different. .
Accordingly, since the nitrogen supplied to the first nitrogen supply line 20, the first and second valves 23 and 26, and the second nitrogen supply line 30 does not pass through the wet tank 31, the dry nitrogen is added to the third nitrogen. It is supplied to the inside of the main body 10 through the nitrogen supply line 60 to perform the calcination process as described above.
Meanwhile, as described above, nitrogen is supplied to the first and second nitrogen supply lines 20 and 30 in a state in which the first and second valves 23 and 26 are opened to sinter the ceramic molded body (including the ceramic capacitor). When an unexpected power failure occurs in the process of performing the first and second valves 23 and 26, the preliminary valves 27 and 28 are automatically opened to open the first and second branch pipes 33 and 34. Nitrogen is supplied to the first and second connection pipes 22 and 25 through the power supply to prevent other defects in the power failure.
In addition, when the air is supplied without supplying nitrogen to the inside of the main body 10 to carry out the calcination process of the ceramic formed body, the first, 2 The air is supplied through the air supply line 80 while the control ball valves 61 and 62 are closed and the third control ball valve 63 installed in the third nitrogen supply line 60 is opened. The plasticizing process can be performed.
Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features. will be.
Therefore, the above-described embodiments are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention described in the above detailed description is represented by the following claims, and the meanings of the claims and All changes or modifications derived from the scope and the equivalent concept should be construed as being included in the scope of the present invention.

10: body 11: heating element
12 blower fan 13 intake vent
14: exhaust port 17: fourth connector
20: first nitrogen supply line 21: the first flow meter
22: first connector 23: first valve
24: 2nd flow meter 25: 2nd connector
26: second valve 27: first spare valve
28: second reserve valve 30: second nitrogen supply line
31: wet tank 32: supply pipe
33: first branch pipe 34: second branch pipe
40: pressure control means 41: exhaust pipe
42: manual valve 43: first proportional control valve
44: exhaust valve 50: exhaust gas exhaust amount adjusting means
51: damper 53: cylinder
54: third connector 60: third nitrogen supply line
61: first control ball valve 62: second control ball valve
63: third control ball valve 70: control unit
80: air supply line

Claims (6)

With the body 10,
A heating element 11 installed at the main body 10 to raise an internal temperature;
A blowing fan 12 installed at one side of the heating element 11 to circulate oxygen and nitrogen introduced into the main body 10;
An inlet 13 connected to one side of the main body 10 to allow oxygen and nitrogen to flow into the main body;
In the gas oven for producing electronic components having an exhaust port 14 connected to the main body 10 for circulating the inside of the main body to discharge the exhaust gas to the outside,
A first valve installed in the first nitrogen supply line 20 and supplying the amount of nitrogen set by the first flow meta 21 to the second nitrogen supply line 30 through the first connection pipe 22 ( 23) and,
The second nitrogen supply through the second connecting pipe 25 to the nitrogen of the amount set by the second flow meta (24) is installed in the rear end of the first valve 23 installed in the first nitrogen supply line 20 A second valve 26 which feeds into the line 30,
A wet tank 31 installed in the second nitrogen supply line 30 to convert nitrogen supplied into moisture-containing nitrogen;
A supply pipe 32 connected between the inlet port 13 and the wet tank 31 to supply nitrogen containing moisture to the inside of the main body 10 through the inlet port 13;
A pressure regulating means (40) installed in the exhaust pipe (41) connected to the exhaust port (14) to automatically adjust the pressure in the main body (10);
Exhaust gas exhaust amount adjusting means (50) installed in the exhaust pipe (41) to regulate the exhaust volume of the exhaust gas,
It comprises a control unit 70 for controlling the driving of the heating element 11, the blowing fan 12, the pressure adjusting means 40, the exhaust gas exhaust amount adjusting means 50,
The third nitrogen supply line 60 is connected between the second nitrogen supply line 30 and the supply pipe 32 to supply dry nitrogen to the inside of the main body 10 through the second nitrogen supply line 30. The first and second control ball valves 61 and 62 are installed at the front and rear ends of the wet tank 31, and the third control ball valve 63 is installed at the third nitrogen supply line 60. Gas ovens for the production of electronic components.
The method according to claim 1,
The pressure control means 40,
A main exhaust pipe 41a connected to the exhaust port 14 through which the exhaust gas is discharged by the manual valve 42;
A first proportional control valve 43 installed on the first exhaust pipe 41b communicating between the upper and lower portions of the manual valve 42 to adjust the displacement by the pressure in the main body 10;
It is installed on the second exhaust pipe 41c communicating between the upper and lower parts of the manual valve 42 to quickly discharge the exhaust gas in the main body 10 in the cooling section of the ceramic capacitor, or set the pressure in the main body during the process. Gas oven for producing electronic components, characterized in that composed of an exhaust valve 44 for discharging the exhaust gas when the above.
The method according to claim 1,
The exhaust gas displacement adjusting means 50,
A damper 51 installed at an upper portion of the exhaust pipe 41 connected to the exhaust port 14 to adjust an exhaust amount of the exhaust gas;
A cylinder 53 connected to the damper 51 by a connecting bar 52 to raise and lower the damper 51;
A third connecting pipe 54 connected to the first nitrogen supply line 20 to supply nitrogen to the cylinder 53 to drive the cylinder 53;
Gas oven for manufacturing electronic components, characterized in that consisting of a solenoid valve (55) installed on the third connecting pipe (54) to open and close the flow path.
delete The method according to claim 1,
The air supply line 80 is connected to the second nitrogen supply line 30, and the air supply line 80 has a ball valve 81, a pressure regulator 82, a third valve 83, and a third flow meter. A gas oven for producing electronic parts, characterized in that 84 are provided in sequence.
The method according to claim 1,
The first and second branch pipes 33 and 34 are installed in the first nitrogen supply line 20 so as to be connected to the first and second connection pipes 22 and 25, and the first and second branch pipes 33 are formed. The first and second preliminary valves 27 automatically open the flow paths of the first and second branch pipes 33 and 34 when a power failure occurs in the process of supplying nitrogen into the main body 10. A gas oven for producing electronic parts, characterized in that 28 is provided.

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