JP2007013210A - Method for manufacturing ceramic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a ceramic substrate which is manufactured with small electric energy, and in which resistance values of a substrate and a conductor layer are controlled easily. <P>SOLUTION: A calcined or non-calcined conductor layer 2 is formed on a ceramic molded or sintered body 1, or a non-calcined insulator layer is further formed on the conductor layer. Resistance heat generation is caused by turning on electricity to the calcined or non-calcined conductor layer 2. The ceramic molded, the non-calcined conductor layer 2, and the non-calcined insulator layer are sintered or calcined. The ceramic sintered body 1 is manufactured by turning on electricity to the ceramic molded body which is mixed with an electrically conductive material powder, causing resistance heat generation, and sintering it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ceramic substrate used in a semiconductor device or a method for manufacturing a ceramic circuit substrate having a circuit formed thereon.

  Conventionally, when forming a circuit on a ceramic substrate, a ceramic powder compact is first sintered in an electric furnace to form a ceramic sintered body, and a conductive paste is printed on the ceramic sintered substrate by screen printing or the like. Then, after forming the circuit pattern of the conductor layer, it was further baked in an electric furnace or the like.

  Even in the cofire method in which the ceramic substrate and the conductor layer are simultaneously sintered, the conductor paste is screen-printed on the ceramic green sheet and sintered in an electric furnace or the like as it is, or further the green sheet is applied on the conductor paste. After lamination, sintering was performed in an electric furnace or the like. Moreover, also about formation of the insulator layer for protecting a conductor layer, the insulating paste was screen-printed on the conductor layer, and it baked with the electric furnace etc.

  On the other hand, in Japanese Patent Publication No. 3-8074, when a metal terminal is attached to a ceramic heater having a metal resistor in a ceramic layer, current is passed through the metal resistor to generate heat, and the brazing material is melted by the generated heat. A method of soldering metal terminals is described. However, in this method, ceramics in which a conductor layer is previously formed is used, and the ceramics or conductor layer is not sintered or fired by energization.

  Japanese Patent Application Laid-Open Nos. 7-296953 and 7-69756 disclose that electric current distribution is made uniform by passing a current through previously sintered ceramics and a conductor layer, and the substrate surface is modified. A method of performing is disclosed. However, this method also relates to the treatment of ceramics and conductor layers that have already been sintered or fired.

Japanese Patent Publication No. 3-8074 JP-A-7-296953 JP 7-69756 A

  As described above, when a ceramic substrate is sintered or a conductor layer is formed on the ceramic substrate, a ceramic molded body or a ceramic substrate with a predetermined circuit pattern formed with a conductor paste is put into an electric furnace or the like. The whole was heated. Therefore, the method using this electric furnace has a problem that the loss of electric power is very large because the entire electric furnace is heated.

  Moreover, when using the board | substrate after baking a circuit pattern as an electrical circuit, it is necessary to control the electrical resistance value of the conductor layer which comprises a circuit to a desired fixed value. However, in the method using the electric furnace, the resistance value is not known unless after firing, and the resistance value of the conductor layer can only be controlled by advanced printing technology and precise temperature control and temperature control. For this reason, it is difficult to precisely control the resistance value of the conductor layer, and if the control range of the resistance value is narrow, the resistance value often goes out of the control range, which causes the product yield to decrease. It was also.

  In view of such conventional circumstances, the present invention can form a ceramic substrate or a circuit board with a small amount of electric power, and can easily control the resistance value of a conductor layer constituting the circuit within a desired range. An object of the present invention is to provide a method for manufacturing a ceramic substrate.

  In order to achieve the above object, a method for manufacturing a ceramic substrate provided by the present invention sinters a ceramic molded body by energizing a ceramic molded body in which ceramic powder and conductive material powder are mixed to generate resistance heat. It is characterized by this.

  According to the present invention, a ceramic substrate can be consumed with much less power consumption than a conventional electric furnace because it is heated and fired or sintered by directly energizing an unfired conductor layer or a ceramic molded body. Can be manufactured.

  In addition, the resistance value of the conductor layer constituting the ceramic substrate or circuit can be easily controlled. Moreover, in the ceramic circuit board obtained, the conductor layer has a very excellent adhesion strength to the ceramic substrate.

  In the present invention, in the production of a ceramic substrate or a ceramic circuit substrate having a circuit formed thereon, an electric furnace or the like is not used as in the prior art, but an unsintered ceramic molded body is energized or provided thereon. By energizing the unfired or fired conductor layer, all the unsintered or unfired parts are simultaneously sintered or fired using the resistance heat generation.

  That is, as one aspect of the present invention, when a ceramic substrate is manufactured, there is a method in which a ceramic molded body mixed with conductive material powder is energized and sintered by resistance heat generation.

  Moreover, an unsintered conductor layer is formed on the unsintered ceramic molded body, and if necessary, an unsintered insulator layer is further formed thereon, and all of these are sintered by energizing the unsintered conductor layer. Or there is a method of firing. Further, as another aspect, an unfired conductor layer is formed on a pre-sintered ceramic sintered body (substrate), and if necessary, an unfired insulator layer is further formed thereon to form an unfired conductor layer. There is a method of firing an unfired conductor layer and an insulator layer by energization.

  Furthermore, an unfired insulator layer is formed on a fired conductor layer provided in advance on the ceramic sintered body, and the unfired insulator layer is fired by energizing the already fired conductor layer. You can also

  Some of these aspects of the method of the present invention will be described in detail. First, when a circuit board is formed by firing only a conductor layer on a ceramic sintered body, a predetermined circuit pattern is formed on a normal ceramic sintered body using a conductor paste or the like. As a circuit pattern forming method, a screen printing method in which the film thickness of the circuit pattern is easy to stabilize as long as it is flat is preferable. Further, as long as it is on a curved surface, a method such as tampo printing or brushing may be used, but it is preferable to form a uniform film thickness in order to make the amount of heat generated during energization uniform.

  Next, the unfired conductor layer formed of the circuit pattern formed of the conductor paste is sufficiently dried. Drying may be performed with a normal electric furnace, a hot plate, or the like. In addition, it cannot energize to the conductor layer before drying. This is presumably because the conductive paste contains a large amount of an organic solvent, which prevents conduction between the conductive particles. Thereafter, a current is passed through the dried unfired conductor layer to cause resistance heat generation, and firing is performed at that temperature to form a conductor layer. When using a conductor having no oxidation resistance, it is necessary to energize in a non-oxidizing atmosphere.

  Since the resistance value of the unfired conductor layer is low at the start of the energization, it will be energized at a somewhat high voltage, but when the conductor layer generates heat due to energization, the temperature gradually increases, and the circuit resistance increases with this temperature increase. The value gradually decreases. At this time, the resistance value or voltage and current of the conductor layer are monitored, and when the predetermined resistance value is reached, the energization is stopped or the energization amount is gradually reduced to easily control the resistance value of the obtained conductor layer. can do.

  It is also possible to subsequently form an insulator layer on the conductor layer formed as described above by the same energization firing. In that case, an insulator paste is applied onto the conductor layer by a method such as screen printing or brushing. This unsintered insulator layer is fired by resistance heating of the conductor layer by energizing the underlying conductor layer.

  The conductor layer constituting the circuit is not particularly limited in terms of material, but the resistance value of the entire conductor layer before firing is preferably 10 MΩ or less. This is because if the resistance value of the unfired conductor layer after drying exceeds 10 MΩ, it becomes difficult for the current to flow, and the calorific value is reduced, which makes firing difficult. In order to reduce the resistance value of the unfired conductor layer during drying, it is preferable to add silver. In particular, when the silver content in the conductor layer is 1.0% by volume or more, the resistance value is further reduced, and firing by energization is facilitated.

  The material of the insulator layer is not particularly limited, and those usually used as insulators for ceramic circuit boards can be used. As the insulator layer, a glassy one is usually used, but when laminating a conductor layer which is a circuit, ceramics as described below may be used.

There is no restriction on the material of the ceramic used as the substrate material. However, ceramics having a large thermal shock fracture resistance coefficient are suitable in that they can be rapidly heated and cooled. Specifically, the thermal shock fracture resistance coefficient is preferably 20 cal / cm · sec or more. The characteristics of the main ceramics used as the ceramic substrate material are shown in Table 1 below. Except for toxic BeO, AlN, SiC, Si ₃ N ₄ , and BN are listed as suitable ceramics, and these composites may also be used. If the temperature raising and lowering rate is reduced, ceramics of 20 cal / cm · sec or less can be used without any problem, but the power consumption required for firing or sintering increases as the temperature raising and lowering rate becomes slower.

  Next, the case where a ceramic substrate and a conductor layer are simultaneously sintered or fired to form a circuit board will be described. First, a conductor layer having a predetermined circuit pattern is formed on a green sheet, which is a ceramic molded body, using a conductor paste. The conductor paste at this time is selected such that the firing temperature is close to the sintering temperature of the ceramic. For example, refractory metals such as tungsten, molybdenum, and tantalum are suitable for ceramics such as alumina, aluminum nitride, and silicon nitride.

  After the unfired conductor layer is dried, the ceramic compact and the unfired conductor layer can be sintered or fired simultaneously by passing an electric current. Even in this case, if the resistance value of the conductor layer before energization is high, current does not flow easily and the amount of heat generation is reduced. Similarly to the case described above, Ag can be added to reduce the resistance value of the conductor layer, and the addition amount is preferably 1.0% by volume or more of the unfired conductor layer. When the material of the conductor layer and / or the ceramic substrate is not oxidation resistant, it can be energized, sintered and fired in an inert gas atmosphere.

  It is also possible to form a circuit pattern on the ceramic green sheet as described above, and further laminate a ceramic green sheet on the circuit pattern, and sinter or fire the whole by energization. However, since it is necessary to pass an electric current through the conductor layer of the circuit pattern buried between the two green sheets, a part of the green sheet is cut off to secure a terminal portion that can be connected to the external power source from the conductor layer. There is a need.

  The value of the current flowing through the unfired conductor layer varies greatly depending on the size of the ceramic substrate, the circuit pattern, and the sintering temperature, and thus cannot be specified unconditionally. However, the conductor layer is sintered as the temperature rises, and the electrical resistance value decreases. Therefore, as described above, the resistance value or current and voltage can be monitored to control the resistance value of the obtained conductor layer. Also, usable conductors and ceramics are the same as described above, and aluminum nitride, silicon nitride, boron nitride and composites thereof excellent in thermal shock resistance are more preferable.

  When a ceramic substrate is manufactured by the method of the present invention, an insulating ceramic powder and a conductive material powder are mixed and used. Specifically, a conductive material powder and an insulating ceramic powder are mixed with an organic solvent, and a sintering aid and an organic binder are added to prepare a slurry. After adjusting the resistance value of the slurry to such an extent that it can be energized, it may be formed into a tape by a doctor blade method, or a granule is produced by a technique such as a spray dryer, and this may be press-molded. Finally, the ceramic molded body is energized and heated by resistance to sinter.

  As the ceramic used at this time, aluminum nitride or silicon nitride excellent in thermal shock resistance is suitable. As the conductive material, it is preferable to use at least one of metals of Group 4A, 5A, and 6A of the periodic table having good wettability with ceramics, or carbides, nitrides, and borides thereof. If the ceramics and the conductive material to be used are not oxidation resistant, it is possible to conduct current sintering in a non-oxidizing atmosphere.

  The electrical resistance value of the ceramic molded body at this time is also preferably 10 MΩ or less. This is because if the resistance value exceeds this value, the flowing current becomes small and the amount of heat generation decreases, which hinders sintering. When the resistance value of the ceramic molded body is too high, a slight amount of Ag powder can be added to the molded body. Although there is no restriction | limiting in particular as the addition amount of Ag, If it is 1.0 volume% or more, since resistance value will fall large, it is especially preferable.

  Also in the production of this ceramic substrate, when the ceramic molded body generates heat by energization, the temperature gradually increases, and the resistance value gradually decreases as this temperature rises. Therefore, the resistance value or voltage and current are monitored, and when the predetermined resistance value is reached, the energization is stopped or the energization amount is gradually reduced to easily control the resistance value of the obtained ceramic sintered body. be able to.

  As described above, in the method of the present invention, only the portion to be sintered or fired is directly heated, so that power consumption can be remarkably reduced as compared with the conventional method of sintering or firing in an electric furnace or the like. In addition, according to the present invention, it is possible to obtain a conductor layer having very strong adhesion strength and film strength with a ceramic substrate as compared with the case of firing in an electric furnace or the like. This is because when the current flows through the conductor layer, it flows along the contact portion of each conductor particle, but since the contact resistance between the particles is relatively higher than the electric resistance in each particle, heat generation is mainly caused by each particle. This is thought to be due to the rapid growth of each particle.

  In particular, when a paste containing glass frit is used as the conductor layer raw material, the glass frit contained in the conductor layer naturally melts. However, when firing in an electric furnace as in the prior art, the glass frit first contacts, and then the conductor particles contained in the conductor layer begin to grow, so that the glass component and the metal component are easily separated, and the film The strength and adhesion strength are reduced. On the other hand, in the electric current sintering method of the present invention, the glass contact time is relatively later than the metal grain growth time as compared with firing in an electric furnace, so that a more uniform film can be obtained. In addition, a conductor layer having excellent film strength and adhesion strength can be obtained. Also, regarding the adhesion strength between the conductor layer and the ceramic substrate, the substrate can be cooled rapidly after energization, compared to an electric furnace, etc., so that the glass frit contained in the conductor is amorphized without being crystallized. It is considered that the adhesion strength is improved.

  In the method of the present invention, when the resistance value of the conductor layer before energization is high, energization is possible by adding silver as described above, but the mechanism is not clear at present. However, when a potential is generated in the conductor layer, silver is likely to move as ions, so that it is presumed that current may easily flow.

  The characteristics of the ceramics used in the following examples are shown in Table 2 below;

[Example 1]
As the ceramic substrate, each ceramic layered body of Al ₂ O ₃ , AlN, and Si ₃ N ₄ having a 25 mm square and a thickness of 2.0 mm is used, and the conductor layer 2 having the circuit pattern shown in FIG. Screen printing was performed on each ceramic sintered body 1. Ag-Pd paste was used as the conductor paste. After printing, the conductor paste was dried at 130 ° C., and a Pt electrode was attached to each terminal portion 2 a of the unfired conductor layer 2 obtained. In addition, the film thickness of the conductor layer 2 after drying was in the range of 25 to 27 μm for all samples.

  When the resistance value of the conductor layer 2 after each sample was dried was measured, it was 100 to 300 kΩ. Moreover, the resistance value of the conductor layer 2 after firing was calculated from the sheet resistance value after firing, and the target was 40Ω. Thereafter, a voltage was applied to each Pt electrode, and a current was passed directly through the unfired conductor layer 2 to heat the conductor layer 2 itself. In addition, the power supply device which can change a voltage value continuously was used for the apparatus which applies a voltage.

  Immediately after the start of voltage application, a voltage of 100 V is applied, and the resistance value begins to gradually decrease as the conductor layer 2 generates heat. Accordingly, the voltage is gradually decreased. The current value was maintained. In this state, baking was performed for 30 seconds until the resistance value of the conductor layer 2 reached a predetermined value. The temperature of the conductor layer 2 at this time was 850 ° C. as a result of monitoring by thermography.

Thereafter, the ceramic substrate for samples of AlN and _Si 3 _{N 4,} and the completion of firing and at the same time a voltage was quenched by the 0V. However, when the ceramic substrate is Al ₂ O ₃ , the ceramic substrate is damaged when the temperature is rapidly increased or decreased, so the temperature is gradually increased up to 850 ° C. at a rate of 60 ° C./min. The temperature was lowered at a rate of 60 ° C./min.

  The resistance value of the conductor layer 2 in the ceramic circuit board of each sample obtained is as shown in Table 3 below. In addition, the resistance value was measured 4 pieces for each sample by the direct current 4 terminal method. For any sample, a good conductor layer can be obtained, and the variation in resistance value is 0.5% at the maximum with respect to the target resistance value of 40Ω, indicating that the resistance value can be easily controlled. .

  For each of the above samples, the adhesion strength of the obtained conductor layer with the ceramic substrate was measured, and the results are shown in Table 4 below.

The amount of electric power used in the above method was 8.0 Wh per one for both the AlN and Si ₃ N ₄ ceramic substrates, and 13.9 Wh for the Al ₂ O ₃ sample.

[Comparative Example 1]
Each ceramic substrate similar to Example 1 was used, the same circuit pattern was printed using the same conductor paste, and baked at 850 ° C. in an electric furnace. In each of the obtained samples, the resistance value and adhesion strength of the conductor layer were measured, and the results are shown in Tables 5 and 6 below.

  It can be seen that the resistance value of the conductor layer in each sample of the comparative example is shifted by 8% at the maximum with respect to the target value. This is because it is impossible to fire while monitoring the resistance value. Moreover, it turns out that all are inferior also about the adhesive strength compared with the sample of the Example which sintered by electricity supply. Note that the amount of power consumed was 1.12 kWh when a belt furnace was used.

[Example 2]
Prepare Al ₂ O ₃ powder, AlN powder, and Si ₃ N ₄ powder, add a predetermined amount of sintering aid, organic binder, and organic solvent to each powder and mix them. Produced. On each green sheet, a conductor layer 2 having the same circuit pattern as that of Example 1 was formed by screen printing using a conductor paste containing W as a main component. Thereafter, a green sheet having the same composition as above was laminated and laminated on the printed surface. In addition, as shown in FIG. 2, in order to attach the electrode 4 required for electricity supply, the notch part 3a was formed in the green sheet 3 to laminate so that the terminal part 2a of the unfired conductor layer 2 might be exposed.

  After sufficiently drying the green sheet and the conductor paste, as shown in FIG. 2, a Pt electrode 4 is attached to each terminal portion 2a of the unfired conductor layer 2, and the conductor layer is energized from the power supply device 5 in a nitrogen atmosphere. The green sheet was degreased by causing 2 to generate heat and heating the green sheet to 900 ° C. and holding it for 5 minutes. Thereafter, a W electrode 4 was attached to each terminal portion 2a. This is because when the W electrode is attached from the beginning, the degreased carbon compound reacts with W to corrode the electrode.

In this state, the unfired conductor layer was energized again, and the green sheet was held at 1600 ° C. for the sample of Al ₂ O ₃ , 1850 ° C. for the sample of AlN and 1700 ° C. for the sample of Si ₃ N ₄ for 10 minutes. . Thereafter, the AlN and Si ₃ N ₄ samples were quenched by setting the applied voltage to 0V. However, since the ceramic substrate was destroyed when the Al ₂ O ₃ sample was rapidly cooled, it was gradually cooled at a rate of 60 ° C./min while gradually decreasing the applied voltage. Table 7 below shows the results of measuring the resistance value of the conductor layer for each of the obtained ceramic circuit boards.

As can be seen from Table 7, the resistance value of the conductor layer of each sample obtained had a variation of ± 2.5% with respect to the target value of 40Ω. The amount of electric power used was 600 Wh for the Al ₂ O ₃ sample, 750 Wh for the AlN sample, and 680 Wh for the Si ₃ N ₄ sample.

[Comparative Example 2]
Laminated green sheets were prepared in the same manner as in Example 2, and each was sintered in an inert gas atmosphere using an electric furnace. The sintering temperature was the same as in Example 2. As a result, the resistance value of the conductor layer of the obtained ceramic circuit board was as shown in Table 8 below.

As can be seen from this result, the variation in the resistance value was very large as compared with Example 2. The amount of power used was 6.7 kWh for the Al ₂ O ₃ sample, 8.9 kWh for the AlN sample, and 7.7 kWh for the Si ₃ N ₄ sample.

[Example 3]
A lead borosilicate glass paste was applied to a thickness of 100 μm on each ceramic circuit board of Al ₂ O ₃ , AlN, and Si ₃ N ₄ obtained in Example 1 by a screen printing method. Thereafter, by passing an electric current through the conductor layer, the conductor layer was heated, and the glass paste was baked to form an insulator layer on the conductor layer. In this case, the amount of electric power required for firing was 5.0 Wh in any sample.

[Comparative Example 3]
In the same manner as in Example 3, after an insulator layer of glass paste was formed on each ceramic circuit board of Al ₂ O ₃ , AlN, and Si ₃ N ₄ , the insulator layer was formed at the same temperature in the atmosphere using a belt furnace. Was baked. As a result, the amount of power used was 57 Wh for all samples.

[Example 4]
Prepare a predetermined amount of each of Al ₂ O ₃ powder, AlN powder, and Si ₃ N ₄ powder, add the same amount of W powder, sintering aid, organic solvent and organic binder as the total volume of the powder, and mix with a ball mill. A slurry was prepared. Using each slurry, a green sheet having a thickness of 1 mm was produced by a doctor blade method. After each green sheet was sufficiently dried, it was cut to a size of 25 mm square, and Pt electrodes were attached so as to sandwich both surfaces of each obtained ceramic molded body.

At this time, the resistance value of each ceramic compact after drying was 528 kΩ for the sample of Si ₃ N ₄ , 488 kΩ for the sample of AlN, and 550 kΩ for the sample of Al ₂ O ₃ . Therefore, first, in order to degrease each ceramic compact, each ceramic compact was heated to 900 ° C. while energizing in a nitrogen atmosphere and observing the temperature by thermography. Thereafter, a W electrode was newly attached to each ceramic compact, and energized in a nitrogen atmosphere, and each ceramic compact was heated to 1650 ° C. About the temperature increase rate, it carried out in the case of 200 degreeC / min in any case.

Thereafter, the temperature was lowered after sintering by holding at 1650 ° C. for 5 minutes. When the applied voltage was set to 0 V and the sample was rapidly cooled, the AlN and Si ₃ N ₄ samples were not damaged, but the Al ₂ O ₃ sample was damaged. Therefore, for the Al ₂ O ₃ sample, a ceramic molded body was prepared again, and after conducting current sintering in the same manner as described above, the voltage was adjusted and the temperature was lowered at a rate of 60 ° C./min. A ligation was obtained. The resistance value of each obtained ceramic sintered body was 40 to 42Ω with the electrode attached.

[Example 5]
Prepare a predetermined amount of each of Al ₂ O ₃ powder, AlN powder, and Si ₃ N ₄ powder, add half the amount of W powder to the total volume of the powder, a sintering aid, an organic solvent, and an organic binder. A slurry was prepared by mixing. Using each slurry, a green sheet having a thickness of 1 mm was produced by a doctor blade method. After each green sheet was sufficiently dried, it was cut to a size of 25 mm square, and Pt electrodes were attached so as to sandwich both surfaces of each obtained ceramic molded body.

The resistance value of each ceramic compact at this time exceeded 20 MΩ for each sample of Al ₂ O ₃ , AlN, and Si ₃ N ₄ . Therefore, 1% by volume of Ag powder was further added to the volume of the whole powder, and a slurry was prepared again in the same manner as above. Each slurry was made into a 1 mm thick green sheet by the doctor blade method, sufficiently dried, then cut to the same size as above, and the resistance was measured again. As a result, the sample of Si ₃ N ₄ was 350 kΩ, AlN This sample was 420 kΩ, and the Al ₂ O ₃ sample was 270 kΩ.

  Next, in order to degrease these ceramic molded bodies, each ceramic molded body was heated to 900 ° C. while energizing in a nitrogen atmosphere and observing the temperature by thermography. Thereafter, a W electrode was attached again, and each ceramic compact was heated to 1650 ° C. and sintered in a nitrogen atmosphere. About the temperature increase rate, all the samples were performed at a rate of 200 ° C./min.

Then, after holding at 1650 ° C. for 5 minutes, the temperature was lowered. When the applied voltage was set to 0 V and quenched, the AlN and Si ₃ N ₄ samples did not break, but the Al ₂ O ₃ sample broke. Therefore, for the Al ₂ O ₃ sample, a molded body was prepared again and sintered in the same manner as described above. Then, the voltage was adjusted and the temperature was lowered at a rate of 60 ° C./min. A ligation was obtained. The resistance value of each ceramic sintered body thus obtained was 40 to 42Ω with the electrode attached.

[Comparative Example 4]
As in Example 5, W powder corresponding to half of the total powder volume, sintering aid, organic solvent and organic binder were added to Al ₂ O ₃ powder, AlN powder and Si ₃ N ₄ powder. And mixed to make a slurry. Using each slurry, a green sheet having a thickness of 1 mm was prepared in the same manner as in Example 1, and after sufficiently drying, cut into a 25 mm square size to obtain a ceramic molded body.

  Pt electrodes were attached so as to sandwich both surfaces of each ceramic molded body. The resistance value of each ceramic molded body at this time was about 25 to 30 MΩ. When a voltage was applied to each ceramic molded body as it was, all samples were short-circuited between the electrodes when a voltage in the vicinity of 1000 V was applied, and sintering by energization could not be performed.

[Example 6]
Each ceramic substrate similar to Example 1 was prepared, and a circuit pattern having the shape shown in FIG. 1 was formed on these substrates using a conductive paste. Copper paste was used as the conductor paste. After the circuit pattern was printed, it was dried at 130 ° C., and the circuit resistance value after drying was measured. All the circuits showed a resistance value of 10 MΩ or more, and the circuit pattern could not be sintered by energization.

  Next, silver powder was added to the same copper paste as above and mixed well. The relationship between the resistance value after drying of the circuit pattern formed with the copper paste added with the silver powder and the silver content in the paste was as shown in Table 9 below. In Table 9, the silver content in the paste was expressed as a volume percentage with respect to copper and glass frit contained in the paste.

  Thereafter, a Pt electrode was attached to the terminal portion of the circuit as the conductor layer, and the conductor layer was resistance-heated by passing a direct current. The circuit resistance value after firing was set to 5.0Ω from the sheet resistance during copper paste firing. Eventually, a voltage of 20 V and a current value of 4 A were maintained. The temperature of the conductor layer at this time was 700 ° C. Table 10 shows the amount of power required for firing the sample of the AlN substrate. When the silver content is 0.9% by volume, the initial resistance value is higher than that of other samples, so that it can be seen that the amount of electric power required for firing is very large.

Results obtained by measuring the resistance value of the conductor layer in Table 11 and the adhesion strength between the conductor layer and the ceramic substrate for each sample obtained by the above firing having a silver content of 1.0% by volume Is shown in Table 12 below. The amount of power required for firing each sample having a silver content of 1.0% by volume is 6.5 Wh when the ceramic substrate is AlN and Si ₃ N ₄ and is 10 when the sample is Al ₂ O ₃ . It was 6 Wh.

It is a top view which shows the state which formed the circuit pattern of the conductor layer on the ceramic sintered compact. It is a top view which shows the state which laminated the circuit pattern of the conductor layer with the ceramic green sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic sintered body 2 Conductor layer 2a Terminal part 3 Green sheet 3a Notch part 4 Electrode 5 Electrode apparatus

Claims (4)

  A method of manufacturing a ceramic substrate, comprising: energizing a ceramic molded body in which ceramic powder and conductive material powder are mixed to cause resistance heating, thereby sintering the ceramic molded body.   2. The method of manufacturing a ceramic substrate according to claim 1, wherein the conductive material is at least one of metals of Group 4A, 5A, and 6A of the periodic table, or carbides, nitrides, and borides thereof. .   The method for producing a ceramic substrate according to claim 1 or 2, wherein a resistance value at the start of energization of the ceramic molded body is 10 MΩ or less.   The method for producing a ceramic substrate according to claim 3, wherein silver powder is further added to the conductive material powder.

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