JP2007178007A - Microwave baking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave baking method for baking ceramics with high precision by reducing contraction and unevenness even when supplying atmospheric gas into a baking furnace when baking the ceramics by microwave heating. <P>SOLUTION: In the microwave baking furnace 1 having a baking furnace main body 2 provided with an introduction pipe 3 for microwave connected with a microwave transmitter 17, an enclosure composed of a thermal insulating material 11 arranged in the inside of the baking furnace main body and allowing microwave to penetrate, a case body 10 arranged in the inside of the enclosure composed of the thermal insulating material and generating heat by microwave, an atmospheric gas supply means for introducing atmospheric gas 4 into the inside of the case body, and an exhaust means 7 for communicating the inside of the case body with the outside of the baking furnace main body, an atmosphere heating part 6 adjacent to a side face of the case body and heating the atmospheric gas composed of a material heated by microwave before the atmospheric gas reaches the case body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microwave firing method for firing an object to be fired such as ceramics by microwave heating.

  In recent years, LSIs, semiconductor chips, and the like have been reduced in size and weight, and a wiring board on which these are mounted is also desired to be reduced in size and weight. In response to such demands, ceramic multilayer wiring boards with internal electrodes and the like in the board enable the required high-density wiring and can be reduced in thickness, and are therefore regarded as important in today's electronics industry. ing.

  Recently, it has been proposed that microwave heating is used when such a ceramic multilayer wiring board is fired. The firing method by microwave heating is a method in which the object to be fired is self-heated and fired by microwaves, compared to a conventional method of firing by heat transfer by external heating such as an electric furnace.

And the firing process of such a ceramic multilayer wiring board is performed while introducing atmospheric gas into the firing furnace. As a method of heating the atmospheric gas introduced into the furnace, a porous body heated by microwaves is disposed in the firing furnace, and a method of passing the atmospheric gas through the furnace, or heating in advance by a heater Methods and the like.
JP 2003-302166 A JP 2003-75077 A

  However, in firing in a conventional microwave firing furnace, when the atmosphere gas to be supplied is supplied into the furnace after being heated in advance by a heater or the like, the temperature of the atmosphere gas when the heated atmosphere gas is introduced into the furnace There was a problem that decreased.

  As described above, when the temperature difference between the temperature in the firing furnace and the introduced atmospheric gas becomes large, there is a problem that the variation in shrinkage ratio of the ceramic multilayer wiring board becomes large and the dimensional accuracy is inferior.

  In addition, when a porous body heated by microwaves is placed in a furnace and the supplied atmospheric gas is heated, generally, firing of multilayer ceramic wiring boards is performed by stacking a plurality of shelves, and each shelf board Since a plurality of objects to be fired are placed on the substrate and a number of multilayer ceramic wiring boards are fired at the same time, the atmospheric gas introduced from the porous body into the furnace diffuses from the porous body in all directions. There is a problem that it is difficult to directly apply the atmospheric gas to the objects to be fired between the shelf boards.

  The present invention has been devised in order to solve the above-described problems, and an object of the present invention is to provide a microwave firing method capable of firing a ceramic multilayer wiring board with small shrinkage variation and high dimensional accuracy. Is to provide.

  The microwave firing method of the present invention includes a firing furnace body provided with a microwave introduction tube, an atmosphere heating portion provided inside the firing furnace body, having an atmosphere gas supply port, and the atmosphere gas A casing comprising a firing portion having a discharge port, and having an atmosphere gas introduction port having an opening area smaller than the supply port between the atmosphere heating portion and the firing portion, and provided around the casing And using a microwave baking furnace provided with a heat-transmitting body that transmits microwaves, supplying the atmospheric gas from the supply port to the atmospheric heating portion and heating the atmospheric gas in advance, The atmosphere gas is introduced into the fired portion from the mouth to perform a firing treatment of the green sheet laminate, and the atmosphere gas is discharged from the discharge port.

  The microwave baking method of the present invention preferably uses a microwave baking furnace provided with a barrier inside the atmosphere heating portion, and the atmosphere gas supplied from the supply port is retained in the atmosphere heating portion by the barrier. Then, the atmospheric gas is introduced into the fired portion.

  According to the microwave firing method of the present invention, a firing furnace body provided with a microwave introduction tube, an atmosphere heating portion and an atmosphere gas provided inside the firing furnace body and having an atmosphere gas supply port Is provided with a casing provided with an introduction port for an atmospheric gas having an opening area smaller than the supply port between the atmosphere heating part and the baking part, and a surrounding part of the casing. Using a microwave baking furnace equipped with a heat-transmitting body that transmits microwaves, supplying the atmospheric gas from the supply port to the atmospheric heating part to preheat the atmospheric gas, and introducing the atmospheric gas from the inlet to the baking part Then, the green sheet laminate is fired and the atmospheric gas is discharged from the discharge port, so that the atmospheric gas supplied from the supply port is uniformly heated in the atmosphere heating portion, The temperature gradient of the incoming atmosphere gas decreases, the decomposition gas generated from the green sheet laminate is discharged efficiently to the outside of the furnace. Therefore, a ceramic multilayer wiring board with high dimensional accuracy with small variation in shrinkage rate can be fired.

  Furthermore, even when a large number of multilayer ceramic wiring boards are fired simultaneously using a plurality of shelf boards, it is possible to directly apply an atmospheric gas to an object to be fired between the shelf boards.

  In addition, according to the microwave baking method of the present invention, using a microwave baking furnace having a barrier inside the atmosphere heating portion, the atmosphere gas supplied from the supply port is retained in the atmosphere heating portion by the barrier and then baking is performed. Since the atmosphere gas is introduced into the portion, the firing capacity of the green sheet laminate increases, and when the flow rate of the atmosphere gas supplied from the supply port increases, such as when a large amount of decomposition gas is generated, the atmosphere gas is also blocked by the barrier. Therefore, the atmospheric gas can stay in the atmospheric heating portion for a longer time, and the atmospheric gas can be reliably heated. As a result, the temperature gradient in the housing can be further reduced, and further, the shrinkage variation can be reduced, and the ceramic multilayer wiring board with high dimensional accuracy can be fired.

  As described above, according to the microwave firing method of the present invention, it is possible to reduce the temperature gradient in the housing, and it is possible to fire a ceramic multilayer wiring board with high dimensional accuracy with a small shrinkage variation.

  The microwave baking method of the present invention will be described below in detail with reference to the accompanying drawings.

  Fig.1 (a) is a plane perspective view which shows an example of embodiment of the microwave baking furnace used for the microwave baking method of this invention. FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG.

  A microwave firing furnace 1 in FIG. 1 is provided with a firing furnace body 2 provided with a microwave introduction tube 3 connected to a microwave transmitter 17, an inside of the firing furnace body 2, and an atmosphere gas 4. Of the atmosphere gas 4 having an opening area smaller than the supply port 5 between the atmosphere heating portion 6 and the firing portion 8. A casing 10 provided with an introduction port 9, a microwave diffusion fan provided inside the firing furnace main body 2, and a heat insulator 11 provided around the casing 10 and transmitting microwaves. ing. Moreover, the green sheet laminated body 12 is arrange | positioned on the shelf board 13 which has the support | pillar 14 in FIG.

  Then, according to the microwave firing method of the present invention, the green sheet laminate 12 supplies the atmosphere gas 4 from the supply port 5 to the atmosphere heating portion 6 to preheat the atmosphere gas 4, and then passes the introduction gas 9 to the firing portion 8. Firing is performed by introducing the atmospheric gas 4. The atmospheric gas 4 is discharged from the discharge port 7 as an exhaust gas (decomposed gas) 15. Such a flow of the atmospheric gas 4 is indicated by an arrow g in FIG.

  According to the microwave baking method of the present invention, the atmospheric gas 4 supplied from the supply port 5 is uniformly heated in the atmospheric heating portion 6, the temperature gradient of the atmospheric gas 4 introduced into the housing 10 is reduced, and green The cracked gas 15 generated from the sheet laminate 12 is efficiently discharged out of the furnace. Therefore, a ceramic multilayer wiring board with high dimensional accuracy with small variation in shrinkage rate can be fired.

  Further, according to such a microwave firing method, even when a large number of multilayer ceramic wiring boards are fired simultaneously using a plurality of shelf boards 13, the atmosphere gas is applied to the fired objects between the shelf boards 13. It can be applied directly.

  Further, when a porous body heated by microwaves is arranged in the furnace and the atmosphere gas is heated, the resistance of the porous body to the atmosphere gas 4 is reduced, and an amount necessary for forming the furnace atmosphere is reduced. Atmospheric gas 4 can be supplied.

  As the green sheet in the present invention, a glass powder, a filler powder (ceramic powder), a mixture of an organic binder, a plasticizer, an organic solvent, or the like is used.

Examples of the glass component include SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M is Ca , Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O system (where M ¹ and M ² are the same or different and Ca, Sr, Mg, Ba or Zn) _{shown), SiO 2 -B 2 O 3} -Al 2 O 3 -M 1 O-M 2 O system (where, ^{M 1} and ^{M 2} are the same as _{above), SiO 2 -B 2 O 3} -M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ³ ₂ O system (where M ³ is the same as above), Pb type glass, Bi type glass, etc. are mentioned.

Examples of the filler include Al ₂ O ₃ , SiO ₂ , a composite oxide of ZrO ₂ and an alkaline earth metal oxide, a composite oxide of TiO ₂ and an alkaline earth metal oxide, Al ₂ O ₃ and Examples thereof include composite oxides containing at least one selected from SiO ₂ (for example, spinel, mullite, cordierite) and the like.

  The mixing ratio of the glass and filler is preferably 40:60 to 99: 1 by weight.

  As the organic binder blended in the green sheet, those conventionally used in ceramic green sheets can be used. For example, acrylic (acrylic acid, methacrylic acid or their homopolymers or copolymers, Specifically, acrylic acid ester copolymer, methacrylic acid ester copolymer, acrylic acid ester-methacrylic acid ester copolymer, etc.), polyvinyl butyral, polyvinyl alcohol, acrylic-styrene, polypropylene carbonate And homopolymers or copolymers of cellulose and the like.

  A green sheet is obtained by adding a predetermined amount of a plasticizer and a solvent (organic solvent, water, etc.) to the glass powder, filler powder, and organic binder as necessary to obtain a slurry. It is obtained by molding to a thickness of about 50 to 500 μm by a die press or the like.

  In order to form a conductive pattern on the surface of the green sheet, for example, a paste of conductive material powder is printed by a screen printing method or a gravure printing method, or a metal foil having a predetermined pattern shape is transferred. It is done. Examples of the conductor material include silver and copper.

  Note that the conductor pattern on the surface of the green sheet includes a portion where a through conductor such as a via conductor or a through-hole conductor for connecting conductor patterns between upper and lower layers is exposed on the surface. These through conductors are formed by means such as embedding by printing a paste made of conductive material powder (conductor paste) in a through hole formed in a green sheet by punching or the like.

  For the lamination of green sheets, it is possible to apply heat and pressure to the stacked green sheets and apply thermocompression by applying an adhesive made of organic binder, plasticizer, solvent, etc. between the sheets. It is.

  Glass ceramics are materials that make it difficult to control the dimensional accuracy after firing, for example, compared to alumina ceramics. This is because glass ceramic with a large amount of glass component added partially generates glass because heat during firing is not uniformly transmitted by the conventional firing method. Therefore, the production method of the present invention by microwave irradiation capable of uniformly transferring heat during firing is suitable for firing glass ceramics. That is, in the case of microwave firing, the green sheet laminate 12 itself self-heats due to the microwave introduced into the firing furnace body 2 through the microwave introduction tube 3 and is provided in the microwave firing furnace 1. The temperature of the surface of the green sheet laminate 12 and the inside of the green sheet laminate 12, which tend to be lower than the inside due to heat dissipation from the surface, due to the self-heating of the housing 10 and the shelf board 13 at the same time. This is because the gradient is extremely small.

  The housing | casing 10 and the shelf board 13 have a microwave absorptivity. As the material, a ceramic material having a large dielectric loss (tan δ) and high microwave absorption is suitable. Accordingly, examples of the ceramic material constituting the housing 10 and the shelf board 13 include silicon carbide materials and alumina materials.

  The atmosphere gas 4 is supplied from the cylindrical supply port 5 into the firing portion 8 adjacent to the atmosphere heating portion 6 and is discharged from the discharge port 7. The atmospheric gas 4 is heated by the radiant heat from the wall surface of the housing 10 by convection in the fired portion 8.

  In addition, since the sum of the cross-sectional areas of the inlet 9 between the atmosphere heating portion 6 and the firing portion 8 is smaller than that of the supply port 5, the atmosphere gas 4 supplied into the atmosphere heating portion 6 is within the atmosphere heating portion 6. Convection can be performed efficiently. For this reason, the atmosphere gas 4 does not directly hit the wall surface of the atmosphere heating portion 6, and it is possible to prevent the temperature of the wall surface of the atmosphere heating portion 6 from decreasing or the atmosphere gas 4 from directly entering the firing portion 8. At this time, if a plurality of inlets 9 are arranged, it becomes easy to make the flow in the fired portion 8 uniform, and the decomposition gas generated from the glass ceramic green sheet laminate 12 is efficiently and continuously discharged from the outlet 7. be able to.

  Next, FIGS. 2A to 2C are main part enlarged views showing an example of a barrier disposed inside the atmosphere heating portion of the microwave baking furnace used in the microwave baking method of the present invention. 2 (a) and 2 (c) are plan perspective views showing the atmosphere heating portion, FIG. 2 (b) is a sectional view of (a), and FIG. 2 (c) is a sectional view of (b). In (c), the same number is attached | subjected to the same component as FIG.

  The microwave baking furnace 1 in FIG. 2 includes a barrier 18 inside the atmosphere heating portion 6. The atmosphere gas 4 supplied from the supply port 5 is retained in the atmosphere heating portion 6 by the barrier 18 and then the baking portion 8. The atmosphere gas 4 can be introduced into the gas.

  In particular, when the flow rate of the atmospheric gas 4 supplied into the housing 10 is large, the atmospheric gas in the atmospheric heating portion 6 is arranged by disposing the barrier 18 so as to block the flow of the atmospheric gas 4 in the atmospheric heating portion 6. It is possible to make the convection of 4 more reliable. For this reason, the atmosphere gas 4 does not directly hit the wall surface of the atmosphere heating portion 6, and it is possible to prevent the temperature of the wall surface of the atmosphere heating portion 6 from decreasing and the atmosphere gas 4 from entering the firing portion 8.

  The shape of the barrier 18 may be circular or rectangular, and may have a through hole 19. A plurality of such barriers 18 may be arranged. Furthermore, the material of the barrier 18 is preferably a ceramic material having a large dielectric loss (tan δ) and high microwave absorption. Accordingly, examples of the ceramic material constituting the barrier 18 include silicon carbide materials and alumina materials.

  As the atmospheric gas 4, a gas such as air or oxygen that decomposes the organic binder, or a gas such as nitrogen or argon that is an inert gas can be used. Further, when copper is used as a conductor, when debinding is performed under a low oxygen partial pressure, the dew point is 40 ° C. or higher for the purpose of changing unsaturated hydrocarbons, which are pyrolysis products of organic binders, to carbon dioxide gas. Atmospheric gas should be used.

  By irradiating the green sheet laminate 12 with microwaves through the microwave-absorbing casing 10 and the microwave-absorbing shelf 13, water vapor of unsaturated hydrocarbon (decomposed gas) generated by thermal decomposition of the organic binder. Carbon dioxide gasification and ceramic sintering by reaction Under the present circumstances, carbon dioxide gasification by reaction with the water vapor | steam of the unsaturated hydrocarbon produced | generated by thermal decomposition of the organic binder is performed by heating the green sheet laminated body 12 in the temperature range of 100-800 degreeC.

  Moreover, although sintering temperature changes with glass-ceramic compositions, it is in the range of about 800-1000 degreeC normally.

  Further, the frequency of the microwave used in the production method of the present invention is preferably 1 to 20 GHz, and particularly preferably 2.45 GHz. If this frequency is less than 1 GHz, the wavelength becomes too long, and the heat generation by the microwaves of the green sheet laminate 12, the housing 10 and the shelf 13 decreases. When the frequency exceeds 20 GHz, the cost of the microwave oscillator 17 becomes high and is not suitable for industrial use. In particular, when the microwave frequency is 2.45 GHz, the oscillator can be used industrially stably, and is relatively inexpensive.

  Further, the microwave baking furnace 1 may be a batch furnace provided with a microwave oscillator 17 and a microwave inlet 9 or may be a large continuous furnace.

  The firing furnace body 2 in the microwave firing furnace 1 is made of a metallic material that does not transmit microwaves, and the microwave introduced into the microwave firing furnace 1 through the microwave introduction tube 3 is the firing furnace body 2. Repeat the reflection. The microwave low-absorption heat insulator 11 is made of an alumina fiber or a foamed alumina material having microwave permeability. Further, the housing 10 and the shelf board 13 are appropriately selected from materials having high microwave absorption, but those having a microwave absorption rate that is equal to or higher than the microwave absorption rate of the green sheet laminate 12. It is good to use. Thereby, during microwave irradiation, the temperature gradient between the surface and the inside of the green sheet laminate 12 becomes extremely small.

If a constrained green sheet is further laminated on the upper and lower surfaces of the green sheet laminate 12 and fired, and the restraint sheet is removed after firing, a ceramic multilayer wiring board with higher dimensional accuracy can be obtained. The constrained green sheet is a green sheet mainly composed of a hardly sinterable inorganic material such as Al ₂ O ₃ and does not shrink during firing. In the laminate in which the constrained green sheets are laminated, shrinkage in the laminating plane direction (xy plane direction) is suppressed by the constraining green sheet that does not shrink, and shrinks only in the laminating direction (z direction). Is suppressed.

  In addition to the hardly sinterable inorganic component, the constrained green sheet may contain a glass component having a softening point not higher than the firing temperature, for example, the same glass as the glass in the glass ceramic green sheet. This glass softens during firing and is bonded to the glass ceramic green sheet, so that the bond between the glass ceramic green sheet and the constrained green sheet is strengthened over the entire surface and is consistently bonded before and after firing. Because power is obtained. The amount of glass at this time is preferably 0.5 to 15% by mass with respect to the inorganic component obtained by combining the hardly sinterable inorganic component and the glass component, the binding force is improved, and the firing shrinkage of the binding green sheet is 0.00. 5% or less.

  The restraint sheet is removed after firing. Examples of the removal method include polishing, water jet, chemical blasting, sand blasting, wet blasting (a method of spraying abrasive grains and water by air pressure), etc., and wet blasting may have a small impact on the conductor pattern on the surface. .

  Examples of the present invention will be described below.

Example 1
As a glass ceramic component, SiO ₂ —Al ₂ O ₃ —MgO—B ₂ O ₃ —ZnO-based glass powder 60% by mass, CaZrO ₃ powder 20% by mass, SrTiO ₃ powder 17% by mass, and Al ₂ O ₃ powder 3% by mass. It was used. To 100 parts by weight of this glass ceramic component, 12 parts by weight of an acrylic resin as an organic binder, 6 parts by weight of a phthalic plasticizer and 30 parts by weight of toluene as a solvent were added and mixed by a ball mill method to form a slurry. Using this slurry, a green sheet having a thickness of 300 μm was formed by a doctor blade method.

Next, a conductor pattern was formed on the green sheet by screen printing using a copper paste. At this time, as copper paste, 100 parts by weight of copper powder (average particle size: 1.0 μm), ₂ parts by weight of Al ₂ O ₃ powder, 2 parts by weight of glass powder having the same composition as the glass, and further as a vehicle component A fixed amount ethylcellulose-based resin and terpineol were added and mixed with three rolls so as to have an appropriate viscosity.

  A green sheet laminate was obtained by stacking a predetermined number of surface layer green sheets and inner layer green sheets having a conductor pattern and a glass ceramic coating layer formed on the surface.

The obtained green sheet laminate was placed in a case made of silicon carbide that self-heats by microwaves, and nitrogen gas having a dew point of 60 ° C. was put into this case at a rate of 100 cm ³ / min per gram of green sheet laminate. While supplying at a flow rate and continuously irradiating 2.45 GHz microwaves and heating at 700 ° C. for 1 hour to remove organic components, firing was carried out at 900 ° C. for 10 minutes. At this time, a shelf board made of silicon carbide was used. Also, the pipe diameter was set so that the cross-sectional area of the atmosphere gas supply port was twice the sum of the cross-sectional areas of the introduction ports.

  After firing, the shrinkage variation within the laminated surface of the obtained ceramic multilayer wiring board was ± 0.10%, and the warpage was 20 μm.

(Example 2)
A ceramic multilayer wiring board was obtained by firing in the same manner as in Example 1 except that the supply amount of nitrogen gas supplied into the housing was 300 cm ³ / min per gram of green sheet laminate. The variation in shrinkage in the laminated surface of this ceramic multilayer wiring board was ± 0.18%, and the warpage was 30 μm.

(Example 3)
The ceramic multilayer wiring board is fired in the same manner as in Example 1 except that the supply amount of nitrogen gas supplied into the housing is 300 cm ³ / min per gram of green sheet laminate and a barrier is provided in the atmosphere heating portion. Got. The variation in shrinkage within the laminated surface of this ceramic multilayer wiring board was ± 0.11%, and the warpage was 22 μm.

Moreover, as shown in Table 1 below, there was no problem in the insulation resistance, strength, and void ratio of Examples 1 to 3.

(Comparative Example 1)
A ceramic multilayer wiring board was obtained by firing in the same manner as in Example 1 except that the pipe diameter was set so that the cross-sectional area of the atmosphere gas supply port was ½ times the sum of the cross-sectional areas of the inlet port. The variation in shrinkage within the laminated surface of the ceramic multilayer wiring board was as large as ± 0.90%, and the warpage was as large as 100 μm. Further, as shown in Table 1, there was no problem in insulation resistance and strength, but the void ratio was high.

(Comparative Example 2) A ceramic multilayer wiring board was obtained by firing in the same manner as in Example 1 except that the housing material was changed to quartz having low microwave absorption. The variation in shrinkage in the laminated surface of this ceramic multilayer wiring board was as large as ± 1.00%, and the warp was as large as 120 μm. Moreover, as shown in Table 1, the insulation resistance and strength were low, and the void ratio was high.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist of the present invention. For example, the above-described embodiment relates to a method for manufacturing a ceramic multilayer wiring board having a wiring conductor for mounting semiconductor elements, semiconductor chips and the like and interconnecting them, but the present invention is applied to other applications. It may be applied.

(A) is a plane perspective view which shows an example of embodiment of the microwave baking furnace used for the microwave baking method of this invention, (b) is sectional drawing in the A-A 'line of (a). (A)-(c) is a principal part enlarged view which shows an example of the barrier arrange | positioned inside the atmosphere heating part of the microwave baking furnace used for the microwave baking method of this invention. 2A and 2C are plan perspective views showing the atmosphere heating portion, FIG. 2B is a sectional view of FIG. 2A, and FIG. 2C is a sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Microwave baking furnace 2 ... Firing furnace main body 3 ... Microwave introduction tube 4 ... Atmosphere gas 5 ... Supply port 6 ... Atmosphere heating part 7 ... Discharge port 8 ... Baking part 9 ... Inlet 10 ... Case 11 ... Heat insulator 12 ... Green sheet laminate 18 ... Barrier

Claims (2)

A firing furnace body provided with a microwave introduction tube;
It is provided inside the firing furnace body, and includes an atmosphere heating portion having an atmosphere gas supply port and a firing portion having an atmosphere gas discharge port, and the supply between the atmosphere heating portion and the firing portion. A housing provided with an inlet for the atmospheric gas having a smaller opening area than the mouth;
A microwave firing furnace provided around the housing and provided with a heat-permeable body that transmits microwaves,
The atmosphere gas is supplied from the supply port to the atmosphere heating portion to preheat the atmosphere gas, and the atmosphere gas is introduced from the introduction port to the firing portion to perform a firing process on the green sheet laminate. The microwave firing method, wherein the atmospheric gas is discharged from the discharge port. Using a microwave baking furnace with a barrier inside the atmosphere heating part,
The microwave firing method according to claim 1, wherein the atmosphere gas supplied from the supply port is retained in the atmosphere heating portion by the barrier, and then the atmosphere gas is introduced into the firing portion.

Images