WO2000069220A1

WO2000069220A1 - Hot plate and conductive paste

Info

Publication number: WO2000069220A1
Application number: PCT/JP2000/002873
Authority: WO
Inventors: Yanling Zhou
Original assignee: Ibiden Co., Ltd.
Priority date: 1999-05-07
Filing date: 2000-05-01
Publication date: 2000-11-16
Also published as: JP2001028290A; EP1185144A1

Abstract

A hot plate comprising a conductive pattern layer having little blisters and excellent adhesion. The hot plate (3) includes conductive pattern layers (10, 10a) provided on a nitride ceramic substrate (9) and made of bismuth, a bismuth oxide, glass frit, and noble metal particles.

Description

Description Hot plate and conductor paste

Field of the invention

The present invention relates to a hot plate and a conductive paste using a ceramic substrate. Background art

In the semiconductor manufacturing process, for example, when heating and drying a silicon wafer that has undergone a photosensitive resin coating step, a heating device called a hot plate is usually used.

As a material for forming the hot plate, a ceramic substrate such as alumina is generally used. A resistor as a conductor pattern layer is formed in a predetermined pattern on one side of the alumina substrate, and a terminal connection pad is formed on a part of the resistor. Such a conductor pattern layer is formed by printing and applying a silver paste for an alumina substrate to a substrate, and then heating and baking. After that, terminal pins are soldered to the pads, and the terminal pins are connected to the power supply via wiring. Then, a silicon wafer to be heated is placed on the upper surface of the hot plate, and by applying a current to the resistor in this state, the silicon wafer is heated to 1 oo ° C or more. I have.

As the conductive paste for forming the conductor pattern layers, the silver particles 6 0 wt% to 8 0 wt ⁰ /. And a glass frit based on lead borosilicate 1 weight ⁰ /. ~ 10 weights. / _0, binder 1% to 1 0% by weight, solvent 1 0 wt ^1% to 3 0% by weight as I contains is generally used (JP-4 one 3 0 0 2 4 No. 9). In particular, glass frit, which is a sub-component, is required to ensure suitable adhesion to the conductor pattern layer. However, when the above-mentioned conventional lead-based paste is directly applied to a ceramic plate, the following inconvenience occurs. That is, the heat in the paste baking causes the oxide in the paste to act on the ceramic, and for example, if the ceramic is aluminum nitride, a reaction that generates a large amount of gas such as nitrogen gas occurs. I will. The main cause for this is thought to be the high lead oxide content in the glass frit. In this case, the high-pressure nitrogen gas generated during paste baking passes through the grain boundaries of the silver particles and tries to escape to the outside. As a result, blisters are likely to occur in the conductor pattern layer, and the accuracy of the formed pattern deteriorates.

By the way, if the amount of glass frit in the paste is extremely reduced, it is expected that the adverse effect of lead oxide will be reduced and the occurrence of blistering will be suppressed to some extent. On the other hand, however, this increases the possibility that the adhesion of the conductor pattern layer will deteriorate. Disclosure of the invention

An object of the present invention is to provide a hot plate provided with a conductive pattern layer having little swelling and excellent adhesion, and a conductive paste suitable for manufacturing the hot plate. In order to achieve the above object, a first aspect of the present invention provides a hot plate using a ceramic substrate provided with a conductor layer. The conductor layer is composed of bismuth or bismuth oxide, glass frit, and noble metal particles. As a result, the conductor layer contains bismuth or bismuth oxide, which is more easily oxidized and reduced than the oxide contained in the glass frit. In the case of a conductor layer containing such a substance, the occurrence of blisters is suppressed even if the amount of glass frit is large. In addition, as the amount of glass frit added can be increased (to 1% by weight or more based on the noble metal particles), the adhesion of the conductor layer is also improved.

A second aspect of the present invention provides a hot plate having a conductor layer having a bismuth or bismuth oxide content of 18% by weight or less. This is 18 weight. /. Over In such a case, the bismuth oxide and the noble metal particles are separated, and a uniform resistance cannot be obtained.

A third aspect of the present invention provides a hot plate, wherein the ceramic substrate is a nitride ceramic substrate or a carbide ceramic substrate. Nitride ceramic substrates and carbide ceramic substrates have excellent thermal conductivity and react with glass frit to generate gas. By using an aluminum nitride substrate having excellent heat resistance and high thermal conductivity among nitride ceramic substrates, a practical hot plate that can withstand use at high temperatures can be obtained. Further, as the carbide ceramic substrate, a silicon carbide substrate can be used.

A fourth aspect of the present invention provides a hot plate having a conductor layer having a glass frit containing zinc borosilicate. It is presumed that glass frit containing zinc borosilicate reacts with nitrides and carbides in the ceramic substrate to generate nitrogen gas, and bismuth or bismuth oxide suppresses such a reaction. Therefore, even if the conductor layer is formed using a material containing this as a component, a large amount of gas is not generated, and blistering is less likely to occur in the conductor layer.

A fifth aspect of the present invention provides a hot plate having a conductor layer containing as a noble metal particle at least one selected from gold particles, silver particles, platinum particles and palladium particles. Gold particles, silver particles, platinum particles and palladium particles are relatively resistant to oxidation even when exposed to high temperatures and exhibit a sufficiently large resistance value, so that a conductor layer suitable as a resistor for heat generation can be easily obtained. Can be.

A sixth aspect of the present invention provides a hot plate having a conductor layer made of bismuth or bismuth oxide, glass frit, noble metal particles, and an organic vehicle. A seventh aspect of the present invention provides a hot plate, wherein the content of bismuth or bismuth oxide in the conductor layer is 18% by weight or less. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic sectional view of a hot-air tune unit according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part of a hot plate unit according to one embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a hot plate unit 1 according to an embodiment of the present invention will be described in detail with reference to FIGS.

The hot plate unit 1 shown in FIG. 1 includes a casing 2 and a hot plate 3. The casing 2 is a metal member having a bottom and has an opening 4 having a circular cross section on an upper side thereof. The casing 2 is not limited to the bottomed one, and may be a bottomless one. The hot plate 3 is attached to the opening 4 via a seal ring 14. On the outer periphery of the bottom 2 a of the casing 2, there are formed lead-out holes 7 for inserting lead wires 6 for supplying current, and each lead 6 is drawn out of the casing 2 from there. I have.

The hot plate 3 of the present embodiment composed of the ceramic substrate 9 is a low-temperature hot plate 3 for drying a silicon wafer W1 coated with a photosensitive resin at 50 ° C. to 300 ° C. .

As the ceramic substrate 9, a nitride ceramic substrate having excellent heat resistance and high thermal conductivity is preferably selected. Specifically, an aluminum nitride substrate, a silicon nitride substrate, a boron nitride substrate It is preferable to select a titanium nitride substrate. Among these, it is particularly desirable to select an aluminum nitride substrate, and then it is desirable to select a silicon nitride substrate. The reason is that these belong to a class having a high thermal conductivity among the above-mentioned nitride ceramics. This ceramic substrate 9 has a thickness of about 1 mn! It has a disk shape of about 10 Omm, and is designed to have a slightly smaller diameter than the outer dimensions of the casing 2.

As shown in FIGS. 1 and 2, a wiring resistance 10 as a conductor layer or a conductor pattern layer is formed concentrically or spirally on the lower surface side of the ceramic substrate 9. A pad 10 a is formed at an end of the wiring resistance 10. The wiring resistance 10 and the pad 10a are made of a conductive paste (noble metal base) P on the surface of the ceramic substrate 9. After printing 1, it is heated and baked. In the hot plate 3 of the present embodiment, the opposite side of the conductor pattern layer, that is, the upper surface side is the heating surface of the silicon wafer W1. The advantage of such a configuration is that temperature unevenness is less likely to occur on the hot plate 3, and the silicon wafer W1 can be heated uniformly.

The wiring resistance 10 and the pad 10a of the present embodiment derived from the noble metal paste P1 contain noble metal particles as a main component, and further contain subcomponents such as glass frit. The noble metal particles used in the present embodiment are preferably scaly noble metal particles having an average particle diameter of 6 μm or less.

The scaly noble metal particles are preferably at least one selected from gold particles (Au particles), silver particles (Ag particles), platinum particles (Pt particles), and palladium particles (Pd particles). This is because these precious metals are relatively hard to oxidize even when exposed to high temperatures and have a sufficiently large resistance value to generate heat when energized. These precious metals may be used alone or in combination of two, three or four as described below. Ag-Au, Ag-Pt, Ag-Pd, Au-Pt, Au-Pd, Pt-Pd, Ag-Au-Pt, Ag-Au-Pd, Au-Pt -Pd, Ag-Au-Pt-Pd may be used in combination. As shown in FIGS. 1 and 2, a base end of a terminal pin 12 made of a conductive material is soldered to each of the hats 10a. As a result, electrical continuity between each terminal pin 12 and the wiring resistance 10 is achieved. A socket 6 a at the end of the lead wire 6 is fitted to the end of each terminal pin 12. Therefore, when a current is supplied to the wiring resistance 10 via the lead wire 6 and the terminal pin 12, the temperature of the wiring resistance 10 rises, and the entire hot plate 3 is heated.

Next, an example of a procedure for manufacturing the hot plate 3 will be briefly described.

A mixture is prepared by adding a sintering aid such as yttria and a binder to the ceramic powder, if necessary, and the mixture is uniformly kneaded with three rolls. Using this kneaded material as a material, a plate-shaped formed body with a thickness of 1 to 10 Omm is produced by breath molding. I do.

Drilling is performed by punching or drilling on the produced formed body to form a pin insertion hole (not shown). Next, the formed body after the drilling step is dried, pre-baked and main-baked to be completely sintered, thereby producing a substrate 9 made of a ceramic sintered body. The firing step is preferably performed by a hot press device, and its temperature is preferably set to about 150 ° C. to 2000 ° C. Thereafter, the ceramic substrate 9 is cut into a circular shape having a predetermined diameter (230 in this embodiment) and is subjected to surface grinding using a puff polishing device.

After the above steps, a precious metal paste P1 prepared in advance is uniformly applied to the lower surface of the ceramic substrate 9 by screen printing.

The noble metal paste P1 used here contains, in addition to the noble metal particles, bismuth or bismuth oxide, glass frit, a resin binder, and a solvent.

The reason why bismuth (B i) or its oxide (bismuth oxide: Bi ₂ 〇 ₃ ) was added to the noble metal paste P 1 is as follows. That is, when these substances are added, it is considered that the reaction between the glass frit and aluminum nitride or silicon carbide is suppressed, and the occurrence of blistering is suppressed as compared with the conventional one, and the wiring resistance 10 and This is because the test results show that the adhesion of the pad 10a is also improved. Bismuth and its oxides are relatively easily oxidized and reduced compared to other oxides, and this property contributes to suppressing blistering and improving adhesion in some way. And at the moment are speculated.

Here, when, for example, aluminum nitride is selected as the substrate material, bismuth oxide reacts with aluminum nitride during paste baking to generate alumina and nitrogen gas, that is, acts as an oxidizing agent for aluminum nitride. In addition, since bismuth is easily oxidized to be bismuth oxide when exposed to air, it may be indirectly understood that this is also an oxidizing agent for aluminum nitride.In addition, for example, silicon nitride is selected as a substrate material. Bismuth oxide It reacts with silicon nitride during baking to generate silica and nitrogen gas, which acts as an oxidizing agent for silicon nitride. Similarly, it can be understood that bismuth is also indirectly an oxidizing agent for silicon nitride.

Bismuth or bismuth oxide is present in small amounts in the precious metal paste P1, specifically 0.1 weight. /. ~ 10 weight. /. The content is preferably about 1% to 5% by weight, more preferably about 1% to 5% by weight, and particularly preferably about 2% to 3% by weight. If the content is too small, the effect of the addition cannot be sufficiently expected, and this does not lead to prevention of blistering and remarkable improvement in adhesion. Conversely, if the content of the above substances is too large, the reaction for generating nitrogen gas is promoted, and in some cases, there is a possibility that blisters may be induced.

The amount of the glass frit is preferably not more than a fraction of the amount of the noble metal particles. The reason is that if the glass frit component in the noble metal paste P1 is at this level, the amount of generated nitrogen gas is not so large, and the adhesion of the wiring resistance 10 and the pad 10a is not impaired. is there. Further, if the conductive component in the noble metal paste P1 increases, the specific resistance of the wiring resistance 10 can be reduced. In the present embodiment, specifically, the noble metal particles in the noble metal paste P1 are 60 weight. /. About 80% by weight, 1 weight of glass frit. /. About 10% by weight.

The Garasufuri' bets, borosilicate zinc _{_{(S i 0 2: B 2}} 0:,: Z N_〇 ₂₎ is preferably used those containing, but especially, the borosilicate zinc as a base containing (i.e. as a main component) Use is more preferred. More specifically, it is desirable to use zinc borosilicate as a base, to which a small amount of oxide is added. Specific examples of oxides include aluminum oxide (A〇J), yttrium oxide (Y ₂ O j, lead oxide (PbO), cadmium oxide (C d〇), chromium oxide (COJ, copper oxide (CuO)). The oxides listed here may be added alone to zinc borosilicate, or may be added in combination of two or more. Oxide is used as an oxidizing agent for substrate materials. In order to act, they are reduced.

The weight ratio of the various oxides listed above is preferably about 1/20 to 1/5 times the weight ratio of zinc borosilicate. If the weight ratio is too small, the abundance of the oxide in the glass frit will increase, and it may not be possible to sufficiently prevent blistering due to nitrogen gas. Conversely, if the weight ratio is too large, the abundance of the oxide in the glass frit will decrease, and the adhesion of the wiring resistance 10 may not be sufficiently improved.

In addition, 3 weight of resin binder as organic vehicle in noble metal paste P1. /. About 15% by weight, and about 10% to 30% by weight of a solvent. Examples of the resin binder include celluloses such as ethyl cellulose. The solvent is a component added for the purpose of improving printability and dispersibility, and specific examples thereof include acetates, cellosolves such as butyl sorbitol, and carbitols such as butyl carbitol. The solvents listed here may be used alone or as a mixture of two or more.

When the noble metal paste P1 is heated at a temperature of about 750 ° C. for a predetermined time, the solvent in the noble metal paste P1 evaporates, and the wiring resistance 10 and the pads 10a are baked on the ceramic substrate 9. The molten glass frit tends to move in a direction approaching the surface of the ceramic substrate 9, and conversely, the noble metal particles tend to move in a direction away from the surface of the ceramic substrate 9.

Then, the terminal pin 12 is joined to the node 10 a via the solder S 1 to complete the hot plate 3, which is further attached to the opening 4 of the casing 2. Hot plate unit 1 is completed. The hot plate unit 1 has no blisters and has a high tensile strength resistor. Further, since the resistance value of the resistor has a small variation, the heating surface of the hot plate is heated to a uniform temperature.

Examples and comparative examples

[Preparation of a sample (when the metal type of the precious metal particles is the same)] In Examples 1 to 5 and Comparative Examples 1 to 3, 100 parts by weight of aluminum nitride powder (average particle size _: 1.1 μm) was added by _: 0:, (average particle size _: 4 μιη) 4 parts by weight 8 parts by weight of an acrylic resin binder (trade name: SA-5545, acid value 1.0, manufactured by Mitsui Chemicals, Inc.) were added and mixed. A kneaded product obtained by uniformly kneading the mixture thus obtained was put into a press molding die and pressed to produce a plate-shaped formed body.

Next, after performing drilling and drying, the molded body was degreased at 350 ° C. for 4 hours in a nitrogen atmosphere to thermally decompose the binder. Further, the degreased compact was fired by hot press at 160 ° C. for 3 hours to obtain an aluminum nitride substrate as the ceramic substrate 9. The pressure of the hot press was set to 150 kg / cm ² .

Then, after performing substrate cutting and surface grinding, a paste application step was performed. In this process, eight kinds of sembles were prepared according to the above procedure, using a noble metal paste P1 having the following composition and setting the thickness at the time of application to about 25 m (see Table 1). ).

As the noble metal particles, only one flaky silver particle having an average particle size of 5 μm was used. The amount of silver particles added to the silver paste as the noble metal paste P 1 was 65 weight for samples 2 and 7. /. Was set to 70% by weight.

Four types of glass frit containing zinc borosilicate as a base (that is, zinc-based) and one containing lead borosilicate as a base (that is, lead-based) were prepared. For the zinc-based glass frit, β, y, and δ, detailed compositions are shown in the lower column of Table 1, respectively. Also, the amount of each glass frit added in the noble metal paste No. 1 is as shown in Table 1.

The amount of bismuth added was set to 3% by weight for samples 1, 3, 4, and 5 (ie, Examples 1, 3, 4, and 5) and to 2% by weight for sample 2 (ie, Example 2). The other samples (Comparative Examples 1, 2, and 3) were set to 0% by weight.

Ethyl cellulose is selected as the resin binder, and butyl carb is used as the solvent. In addition to selecting Thor, the addition amount of the noble metal paste P1 was set to 5% by weight and 15% by weight, respectively.

[Comparison test and its results]

Using each of the obtained eight types of samples, paste printing and baking were performed on the substrate 9 to form a 2 mm square test pattern at a plurality of locations. Then, a tensile strength test was performed on these test patterns, and the average of the measured values (kgf / 2 mmD) was calculated. In addition, the presence or absence of blisters in the test pattern was examined by observation with both the naked eye and an optical microscope. In addition, the sample was heated to 180 ° C by applying a voltage, and the difference between the maximum temperature and the minimum temperature on the heated surface (° C) was measured using Thermopure (IR-620 12 2-001 2 manufactured by Nippon Datum). ). Table 1 shows the results of these tests.

Bi or glass frit

Particle its oxidation blister tensile strength temperature difference

No.

(wt%) Material addition and amount (kgf / 2mmD) (.c) Amount (wt%) (wt%)

1 (Example 1) Ag 70 3 (Ζπ series, 3 None 12.2 0.5

2 (Example 2) Ag 65 2 Ζ (Ζη series, 5 None 11.8 0.4

3 (Example 3) Ag 70 3 β (Ζη system), 3 None 9.4 0.5

4 (Example 4) Ag 70 3 7 (Ζη system), 3 None 9.8 0.5

5 (Example 5) Ag 70 3 δ (Ζη system), 3 None 10.1 0.4

6 (Comparative Example 1) Ag 70 0 α (Ζπ system, 3 Yes 5.2 0.4

7 (Comparative Example 2) Ag 65 0 (Zn-based), 5 Yes 4.8 0.4

8 (Comparative Example 3) Ag 70 0 Pb system, with 3 0.5

Ag 56.6

9 (Example 6) 2.1 Zn-Pb type None 10.0 0.5

Pd 10.3

Ag 56.6

10 (Example 7) 15.1 Zn-Pb type None 9.5 0.9

Pd 10.3

Ag 56.6

11 (Example 8) 25.0 Zn-Pb based 5.8 5.0

Pd 10.3 (note)

a: borosilicate zinc _{8 Owt%, A 1 2 0} :, containing 2 OWT%.

beta: borosilicate zinc 8 OWT%, the _{_{A 1 2 0 3 1 Owt%}} , including _{_{C r 2 0 3 1 Owt%}} γ:. borosilicate zinc 9 0 wt%, 5 wt% of P B_〇, Contains 5 wt% of CdO.

δ: 85 wt% of zinc borosilicate and 15 wt% of Cr ₂ r _{3. As} is clear from Table 1, no blistering was observed in Examples 1 to 5 and the pattern formation accuracy was low. It was excellent. Moreover, the values of the tensile strength were extremely high, and all exceeded 9 kgf / 2 mm.

On the other hand, in Comparative Example 3, blistering was observed, and the pattern formation accuracy was poor. In Comparative Examples 1 and 2, although no blistering was observed, the tensile strength was about half of the value of the tensile strength of each of Examples 1 to 5. In other words, it was proved that the addition of a small amount of bismuth was extremely effective in improving the tensile strength.

[Preparation of sample (when the metal type of noble metal particles is different)]

In Example 6, the silicon nitride powder (average particle size 1. 1 / im) 4 5 parts by weight, Y ₂ 0 ₃ (flat Hitoshitsubu径0. 4 / im) 2 0 parts by weight, A 1 ₂ 0 ₃ ( . The average particle diameter of 0. 5 μ m) 1 5 parts by weight, S i 0 ₂ (average particle size ◦ 5 / xm) 2 0 parts by weight, an acrylic resin binder (Mitsui Chemicals Co., Ltd., trade name: SA - 5 4 5, acid value 1.0) 8 parts by weight were mixed.

A kneaded product obtained by uniformly kneading the mixture thus obtained was put into a press mold and pressed to produce a plate-shaped formed body.

Next, after performing drilling and drying, the molded body was degreased at 350 ° C. for 4 hours in a nitrogen atmosphere to thermally decompose the binder. Further, the degreased molded body was subjected to hot press firing at 160 ° C. for 3 hours to obtain a silicon nitride substrate as the ceramic substrate 9. It should be noted that the pressure of the hot press was set to 1 5 0 k gZ cm ^2. After that, the substrate was cut out and the surface was ground, and then a paste application step was performed. Here, the noble metal paste P 1 has the following composition, and The thickness at the time of application was set to about 25 m to produce Sanal 9. Here, bismuth oxide was used instead of bismuth.

• Noble metal particles: 56.6 parts by weight of silver particles (Showei Chemical Industry Ag-520) and 10.3 parts of palladium particles (Showei Chemical Industry Pd-213)

. Glass frit: S i 0 ₂ is 1.0 parts by weight, B ₂ _0:, is 2.5 parts by weight,

Zn_〇 is 5.6 parts by weight, 1) 0 0.6 parts by _{_{weight, • B i 2 0 3:}} 2. 1 part by weight,

• Resin binder: 3.4 parts by weight,

• Solvent: 17.9 parts by weight butyl carbitol.

Then, by heating the applied noble metal paste P1 at a temperature of about 750 ° C. for a predetermined time, the wiring resistance 10 and the pad 10a were baked, and the hot plate 3 of Example 6 was completed.

In Examples 7 and 8, in 45 parts by weight of silicon carbide powder (average particle size: 1.1 / xm), 0.5 parts by weight of C (force), an acrylic resin binder (trade name, manufactured by Mitsui Chemicals, Inc.) : SA-545, acid value 1.0) 8 parts by weight were mixed.

A kneaded product obtained by uniformly kneading the mixture thus obtained was placed in a press mold and pressed to produce a plate-shaped formed body.

Next, after drilling and drying, the molded body was degreased at 350 ° C. for 4 hours in a nitrogen atmosphere to thermally decompose the binder. Further, the degreased compact was fired by hot press at 1900 ° C. for 3 hours to obtain a silicon nitride substrate as ceramic substrate 9. The pressure of the hot press was set to 150 kg gZc rrr '. Further, the silicon nitride substrate was fired in the air to provide an Sio ₂ layer on the surface.

Next, samples 10 and 11 (Examples 7 and 8) were obtained by performing the first paste coating process using the noble metal paste P 1 having the following composition (that is, pastes A and B). Produced. Paste A>

-Noble metal particles: 56.6 parts by weight of silver particles (Showei Chemical Industry Ag-520) and 10.3 parts of palladium particles (Showei Chemical Industry Pd-213)

'Garasufuri' DOO: S I_〇 ₂ 1.0 parts by weight, B ₂ 0 ₃ 2 5 parts by weight,

5.6 parts by weight of ZnO 1 ^ 0 is 0.6 parts by weight,

• B i ₂₀ _;) : 15.1 parts by weight,

• Resin binder: 3.4 parts by weight,

• Solvent: 17.9 parts by weight butyl carbitol.

• Noble metal particles: 56.6 parts by weight of silver particles (Showei Chemicals Ag-520), 10.3 parts by weight of palladium particles (Showei Chemicals Pd-213),

• Glass frit: S I_〇 ₂ 1.0 parts by weight, B ₂ 〇 ₃ 2.5 parts by weight,

5.6 parts by weight of ZnO, 6 parts by weight of PbC ^ SO.

_{_{• B i 2 0 3: 25.}} 0 parts by weight,

• Resin binder: 3.4 parts by weight,

• Solvent: 17.9 parts by weight butyl carbitol.

[Comparison test and its results]

With respect to the samples 9, 10, and 11 of the obtained Examples 6, 7, and 8, the same comparative test as that of Examples 1 to 5 and Comparative Examples 1 to 3 was performed. As a result, in Examples 6 and 7, no swelling was observed in the wiring resistance 10 and the pad 10a. In Example 8, in addition to blistering, the temperature difference on the heated surface was as large as 5 ° C.

Therefore, according to each example of the present embodiment, the following effects can be obtained.

(1) Examples: In hot plate 3 of ~ 5, bismuth, glass frit and A wiring resistance 10 and a pad 10a made of silver particles are formed. In the hot plates 3 of the sixth and seventh embodiments, a wiring resistance 10 and a pad 10a composed of bismuth oxide, glass frit, silver particles, and palladium particles are formed.

Accordingly, the occurrence of blisters can be suppressed without reducing the amount of glass frit added, and the adhesion can be improved. Therefore, a highly reliable hot plate 3 with excellent pattern formation accuracy can be obtained.

In Examples 1 to 5, bismuth in the noble metal base P1 was replaced with almost the same amount of bismuth oxide, and in Examples 6 and 7, bismuth oxide in the noble metal paste P1 was replaced with almost the same amount of bismuth. You may.

(2) In Examples 1 to 5, an aluminum nitride substrate having particularly excellent heat resistance and high thermal conductivity is used as the ceramic substrate 9. Therefore, a practical hot plate 3 that can withstand use at high temperatures can be obtained.

Note that the embodiment of the present invention may be modified as follows.

• Spherical precious metal particles may be used instead of scaly precious metal particles. In addition, it is not limited to using only one kind of precious metal particles, and two kinds (for example, scale-like ones and spherical ones) or more may be used as needed.

• The ceramic substrate 9 made of aluminum nitride or silicon nitride is not limited to one manufactured by a press molding method, but may be one manufactured by a sheet molding method using a doctor blade device, for example. When the sheet forming method is adopted, for example, the wiring resistance 10 can be provided between the stacked sheets, so that the hot plate 3 for high temperature can be manufactured relatively easily.

• The conductor pattern layer is not limited to the wiring resistance 10 ゃ pad 1 Oa exemplified in the embodiment, but may be another conductor pattern layer, that is, a conductor pattern layer that is not a heating resistor.

• As a method of applying the noble metal base P1 to the ceramic substrate 9, not only a screen printing method but also, for example, a stamping method and other methods. • The above oxides are not only contained in the noble metal paste P1 as a separate component from the glass frit, but are also contained in the noble metal paste P1 as added to the glass frit as a sub-component of the glass frit. May be. However, the oxide contained as a sub-component of the glass frit is preferable in that it is uniformly dispersed in the noble metal paste P1.

Claims

The scope of the claims

1. A hot plate having a ceramic substrate having a conductor layer, wherein the conductor layer is made of bismuth or bismuth oxide, glass frit, and noble metal particles.

2. The hot plate according to claim 1, wherein the content of the bismuth or bismuth oxide is 18% by weight or less.

3. The hot plate according to claim 1, wherein the ceramic substrate is a nitride ceramic substrate or a carbide ceramic substrate.

4. The hot plate according to any one of claims 1 to 3, wherein the glass frit contains zinc borosilicate.

5. The hot plate according to any one of claims 1 to 3, wherein the noble metal particles are at least one selected from the group consisting of gold particles, silver particles, platinum particles, and palladium particles.

6. A conductor base comprising bismuth or bismuth oxide, glass frit, precious metal particles and an organic vehicle.

7. The conductor base according to claim 6, wherein the bismuth or bismuth oxide content is 18% by weight or less.