WO2000069217A1

WO2000069217A1 - Hot plate and conductive paste

Info

Publication number: WO2000069217A1
Application number: PCT/JP2000/002875
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: JP2001028291A

Abstract

A hot plate including a conductor pattern layer that can hardly separate. The hot plate (3) includes a conductor pattern layer (10, 10a) on a ceramic substrate (9). The conductor pattern layer (10, 10a) consists of scalelike particles of precious metal.

Description

Description = Hot plate and conductor paste Technical field

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 hot plate using a ceramic substrate has been frequently used in recent years.

A conductor layer is formed in a predetermined pattern on one side surface of the ceramic substrate, and a terminal connection pad is formed on a part of the conductor pattern layer. Such a conductor pattern layer is formed by printing and applying a conductive noble metal paste on a substrate and heating and baking it, as described in Japanese Patent Application Laid-Open No. Hei 4-32049. The conductor paste usually contains one kind of noble metal particles (for example, silver particles having an average particle size of about 5 m and a substantially spherical shape). Terminal pins are soldered to the pads, and power is connected to the terminal pins via wires.

Then, a silicon wafer as an object to be heated is placed on the upper surface side of the hot plate, and electricity is supplied in this state, so that the silicon wafer becomes 100. It is heated to C ~ 800 ° C.

However, when the above-mentioned conventional noble metal paste is printed on a substrate and baked, voids are easily formed in the conductive pattern layer, and peeling is likely to occur. For this reason, there has been a strong demand for a conductor pattern layer, which is difficult to peel.

In addition, it was necessary to increase the specific resistance in order to increase the amount of heat generated in the conductor pattern layer. Disclosure of the invention

A first object of the present invention is to provide a hot plate having a conductor layer that is difficult to peel off.

A second object of the present invention is to provide a hot plate having a conductor layer having a large specific resistance and being difficult to peel off.

A third object of the present invention is to provide a conductor paste suitable for manufacturing the above-mentioned excellent hot plate.

According to a first aspect of the present invention, there is provided a hot plate comprising a ceramic substrate and a conductor layer. The conductor layer is made of substantially scaly noble metal particles. The conductive layer of the present invention is more likely to be in surface contact with each other than the conventional conductive layer consisting only of substantially spherical noble metal particles, and is more likely to be in a state where noble metal particles are densely packed after baking. On the other hand, spherical noble metal particles are in point contact, so that voids tend to occur in the conductor layer. As described above, in the present invention, the void ratio in the conductor layer is reliably reduced, and the bonding area between the particles is increased. As a result, a sufficient tensile strength is secured for the conductor layer, and a conductor layer that is difficult to peel off can be obtained. Further, the surface roughness Ra can be set to 1 or less, and the variation in the resistance value of the conductor pattern layer can be reduced.

The average particle size of the substantially scaly noble metal particles is preferably 6 μπι or less. By setting in this way, it is possible to more reliably achieve a reduction in the void ratio and an improvement in the tensile strength. In particular, when the distance exceeds 6 m, the thickness of the conductor layer (resistor) varies greatly (the surface roughness Ra increases), and the resistance tends to vary. The substantially flaky noble metal particles are preferably at least one selected from gold particles, silver particles, platinum particles and palladium particles. These metal particles are relatively resistant to oxidation even when exposed to a high temperature, and have a sufficiently large resistance value, so that a conductor layer suitable as a resistor for generating heat can be easily obtained.

It is preferable that the aspect ratio of the major axis to the minor axis of the substantially scaly noble metal particles is 1.5 or more. When the aspect ratio is 1.5 or more, the particles are likely to be in surface contact with each other. Conversely, when the aspect ratio is less than 1.5, the particles are in point contact with each other, and the particles are in point contact. There is a possibility that the reduction of the lead rate and the improvement of the tensile strength cannot be sufficiently achieved. According to a second aspect of the present invention, there is provided a hot plate comprising a ceramic substrate and a conductor layer. The conductor layer is composed of substantially granular noble metal particles and substantially scaly noble metal particles. The conductor layer of the present invention is more likely to be densely packed with noble metal particles after baking than a conventional conductor layer comprising only substantially spherical noble metal particles. Therefore, the void ratio in the conductor layer decreases. On the other hand, since almost noble metal particles are used, the particles do not completely come into surface contact with each other, and a constant resistance value can be obtained. Therefore, it is possible to obtain a resistor that is hard to peel and has a high resistance value. In addition, since it is easy to be dense, there is no variation in resistance value, and the temperature uniformity of the heated surface is high.

The shape of the granular particles may be spherical, microcrystalline, or crushed. Of these, the spherical shape is the best. This is because the particle size is easy to control and the reproducibility of the resistance value is excellent.

The average particle size of the substantially granular noble metal particles is preferably 3 μm or less, and the average particle size of the substantially scaly noble metal particles is preferably 6 μm or less. With such a setting, it is possible to more reliably achieve a reduction in the void ratio, an improvement in the tensile strength, and an improvement in the resistance value.

The substantially scaly noble metal particles are preferably made of two or more kinds of particles having different average particle diameters. In this case, the void ratio in the conductor layer is further reduced. Therefore, it is possible to reliably obtain a conductor layer that is difficult to peel.

It is preferable that the conductive layer contains substantially scale-like noble metal particles 5 to 25 times as large as substantially granular noble metal particles. In this case, the void ratio in the conductor layer is further reduced. Therefore, it is possible to more reliably obtain a conductor layer that is difficult to peel. If the content ratio of the substantially scaly noble metal particles to the substantially granular noble metal particles is less than 5 times, the number of the substantially granular noble metal particles becomes relatively large, so that it is difficult to sufficiently reduce the void ratio. Become. On the other hand, when the content ratio exceeds 25 times, the number of substantially scale-like noble metal particles becomes relatively large, and as a result, the resistance value may be too small.

According to a third aspect of the present invention, there is provided a conductive paste comprising substantially scaly noble metal particles, an oxide, and an organic vehicle.

In the fourth embodiment of the present invention, the substantially granular noble metal particles, the substantially scaly noble metal particles, and the acid A conductive paste comprising a compound and an organic vehicle is provided.

The substantially scaly noble metal particles are preferably at least one selected from gold particles, silver particles, platinum particles and palladium particles.

The substantially scaly noble metal particles are preferably made of two or more kinds of particles having different average particle diameters.

It is preferable that the conductive paste contains approximately scale-like noble metal particles 5 to 25 times as large as substantially granular noble metal particles.

The average particle size of the substantially granular noble metal particles is preferably 3 μm or less, and the average particle size of the substantially scaly noble metal particles is preferably 6 μm or less. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cross-sectional view of a hot plate unit according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the hot plate unit of FIG.

Figure 3 is a conceptual diagram showing the appearance of precious metal particles in the conductor pattern layer (when the precious metal particles are only one type of scale-like one).

Fig. 4 is a conceptual diagram showing the appearance of the noble metal particles in the conductor pattern layer (in the case of two types of noble metal particles, scaly and spherical).

Figure 5 (a) shows spherical noble metal particles (ie, A particles), Figure 5 (b) shows flaky noble metal particles (ie, B particles), and Figure 5 (c) shows flaky noble metal particles (ie, C particles). Fig. 5 (d

() Is an enlarged photograph of flaky precious metal particles (ie, D particles) by SEM. 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 as main components.

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. In addition, the casing 2 is not limited to the bottomed one, but the bottomless one. It may be something. The hot plate 3 is attached to the opening 4 via an annular seal ring 14. On the outer periphery of the bottom 2 a of the casing 2, a lead wire drawing hole 7 for inserting a lead wire 6 for supplying current is formed, and each lead wire 6 is connected to the casing 2 from there. It has been pulled out.

The hot plate 3 of the present embodiment composed of the ceramic substrate 9 is a low-temperature hot plate for drying the silicon wafer W1 coated with the photosensitive resin at 50 ° C. to 300 ° C. 3 The hot plate unit 1 has an operating temperature range of 300 ° C. to 800 ° 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, or a nitride nitride substrate is used. It is preferable to select a titanium 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 the category of high thermal conductivity. In addition to the nitride ceramic, an oxide ceramic / carbide ceramic can be used as a substrate material. In particular, carbide ceramics are advantageous because of their high thermal conductivity. Silicon carbide, boron carbide or titanium carbide can be used as the carbide ceramic.

The ceramic substrate 9 of the present embodiment has a disk-like thickness of about 1 mm! It is a plate-like object of about 25 mm in diameter, 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 pattern layer is formed concentrically or spirally on the lower surface side of a ceramic substrate 9 made of aluminum nitride or the like. A pad 10 a is formed at an end of the wiring resistance 10. Note that the wiring resistance 10 and the pad 10a are formed of a conductive noble metal paste (synonymous with a conductive paste and a resistor paste for forming a resistor) on the surface of the ceramic substrate 9. In the following embodiments, the noble metal paste will be described. After printing P1, it is heated and baked. In the hot plate 3 of the present embodiment, the opposite side of the conductor pattern layer forming layer, that is, the upper surface side is the heating surface of the silicon wafer W1. Such a structure The advantage of this configuration is that temperature unevenness is less likely to occur in 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 are

However, it contains only one kind of noble metal particles G2 (specifically, only flaky noble metal particles G2) as a main component, and further contains subcomponents such as glass frit. FIG. 3 conceptually shows the appearance of the scaly noble metal particles G2. The amount of glass frit is very small compared to the amount of noble metal particles G2. Therefore, for convenience of illustration and description, the glass frit is omitted in the figure.

In this case, the scaly noble metal particles G 2 often have an average particle size of 6 μm or less.

In particular, it is preferably about 3 μτα to 5 μm. By setting the average particle size in the above preferable range, it is possible to more reliably achieve a reduction in the void ratio and an improvement in the tensile strength.

The scaly noble metal particles G2 are at least one selected from gold particles (Au particles), silver particles (Ag particles), platinum particles (Pt particles), and palladium particles (Pd particles). It's preferable to be there. 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. Of course, these noble metals may be used alone or in combination of two, three or four as described below. That is, 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. In the present embodiment, the scaly noble metal particles G2 are at least plate-like or rod-like particles that do not exhibit a spherical shape such as the noble metal particles G1, and the ratio of the major axis to the minor axis, in other words, the major axis It is desirable that the aspect ratio between the steel and the thickness be 1.5 or more. Incidentally, in the present embodiment, the spherical noble metal particles G1 preferably have an aspect ratio of about 1.0 to 1.5 (but not including 1.5). Granular particles include, for example, spherical, microcrystalline, or dendritic. The aspect ratio is not limited to a value within the above range. As long as the effects of the present invention are not impaired, it is acceptable to select scaly particles or granular particles. When the aspect ratio of the scaly noble metal particles G2 is 1.5 or more, the shape tends to be different from the spherical one having an aspect ratio close to 1.0. As a result, the effect of the particle shape can be expected, and the reduction of the void ratio and the improvement of the tensile strength can be sufficiently achieved.

Further, the wiring resistance 10 and the pad 10a of the present embodiment include a plurality of types of noble metal particles Gl and G2 having different shapes as main components, and further include subcomponents such as glass frit. It may be. More specifically, the wiring resistance 10 is configured to include not only the scaly noble metal particles G2 but also the granular noble metal particles G1 (that is, two kinds of noble metal particles G1, G2). . Fig. 4 conceptually shows the appearance of these noble metal particles Gl and G2. The amount of glass frit is extremely small compared to the amounts of the noble metal particles G 1 and G 2. Therefore, for convenience of illustration and description, the glass frit is omitted in FIG.

In this case, the granular noble metal particles G1 preferably have an average particle diameter of 3 μm or less, and particularly preferably about 0.5 μm to 2 m. The scaly noble metal particles G 2 preferably have an average particle diameter of 6 μm or less, and particularly preferably about 3 μm to 5 μm. Further, the scaly noble metal particles G2 may be one of two or more kinds having different average particle diameters.

In the wiring resistance 10 and the pad 10a, the scale-like noble metal particles G2 are contained more than the granular noble metal particles G1. More specifically, the flake-like noble metal particles G2 that are 5 to 25 times the granular noble metal particles G1 are often contained, and particularly, the flake-like noble metal particles G1 are preferably contained 6 to 20 times. Les ,.

If the content ratio of the scaly noble metal particles G2 to the substantially granular noble metal particles G1 is too small, the granular noble metal particles G1 become relatively large, so that the void ratio can be sufficiently reduced depending on the condition setting. This is because it may disappear. On the other hand, if the content ratio is too large, on the contrary, the scale-like noble metal particles G2 become relatively large, so that paste printability may be reduced. Therefore, the printing thickness tends to vary, and it is difficult to accurately and uniformly form the wiring resistance 10 and the pad 10a with a uniform thickness. Also, depending on the condition setting, it may not be possible to sufficiently reduce the void ratio. Here, the granular noble metal particles Gl are desirably at least one selected from gold particles, silver particles, platinum particles, and palladium particles for the same reason as the flaky noble metal particles G2. Of course, these noble metals may be used alone or in combination of two, three or four as described below. That is, Ag—Au, Ag-Pt, Ag—Pd, Aυ-Pt, Au-Pd, Pt—Pd, Ag—Au-Pt, Ag-Au- The combination of Pd, Au-Pt-Pd, Ag-Au-Pt-Pd may be used.

The metal species of the granular noble metal particles G1 and the scale-shaped noble metal particles G2 may be a combination of the same type or a combination of different types.

As shown in FIGS. 1 and 2, the base end of the terminal pin 12 made of a conductive material is soldered to each pad 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. Accordingly, 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 1 ° 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 an iterator or a binder as necessary to ceramic powder typified by aluminum nitride or the like, and this is preferably formed by a three-roll mill. Knead evenly. Using this kneaded material as a material, a plate-shaped formed body having a thickness of about several mm is produced by press molding.

Drilling is performed by punching or drilling on the produced formed body to form a pin insertion hole (not shown). Next, the substrate 9 made of a ceramic sintered body is manufactured by drying, pre-baking, and main-baking the completely formed body after the drilling step and completely sintering. The baking process is often performed by a hot blessing apparatus, and the temperature is preferably set at about 1500 to 2000 ° C. Thereafter, the fired ceramic substrate 9 is cut out to a predetermined diameter (230 in the present embodiment and in a circular shape, and the surface is preferably ground 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 preferably by screen printing.

The noble metal paste P1 used here is a resin binder as a glass frit or an organic vehicle, in addition to the one kind of noble metal particles G2 (or the two kinds of noble metal particles G1 and G2). Contains solvents.

The amount of the glass frit is preferably 1 Z5 or less of the amount of the noble metal particles G 2 (or G 1 and G 2), and more preferably about 1/10 to lZ100. . The reason is that the more conductive components in the noble metal paste P1, the more advantageous it is in achieving a reduction in specific resistance.

Specifically, in the noble metal paste P1, the noble metal particles G2 (or G1 and G2) are contained in a total of about 60% to 80% by weight, and the glass frit is 1% to 10% by weight. % Is included.

As the glass frit, borosilicate zinc (S i: 〇 _3:. Z _nOj a base one scan, and specific examples of it obtained by addition of a small amount of metal oxide to have been used metal oxide, oxide aluminum (A l ₂ Oj, oxide cum thorium (Y ₂ 0.,), lead oxide (P b O), cadmium oxide (C dO), chromium oxide (C _r Oj, copper oxide (Cu_〇), bismuth oxide ( one or those of two or more selected from B i ₂ Oj.

In addition, the precious metal paste P1 contains about 3% to 15% by weight of a resin binder as an organic vehicle and 10% by weight of a solvent. /. ~ 30 weight. / ₀ is included. 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 cellulose, and carbitols such as butyl carbitol. Is mentioned.

When the noble metal paste P1 applied on the ceramic substrate 9 is heated at a temperature of about 750 ° C for a predetermined time, the solvent in the noble metal paste P1 volatilizes, and the wiring resistance 10 and the pad 10a are reduced. Burned. The molten glass frit tends to move in a direction approaching the ceramic substrate 9, whereas the noble metal particles G 2 (or G 1 and G 2) Tend to move away from the lock substrate 9.

After that, the terminal pins 12 are joined to the pad 10a via the solder S1 to complete the hot plate 3, which is then attached to the opening 4 of the casing 2, as shown in Fig. 1. The desired hotplate Tunit 1 is completed.

Hereinafter, some examples and comparative examples will be introduced.

(Examples and Comparative Examples)

[Preparation of sample (when noble metal particles have the same metal type)]

In Examples 1 to 6 and Comparative Examples 1 to 3, nitride Aruminiumu powder (average particle size 1 1 _mu m.) In 1 0 0 parts by weight, Y ₂ _0:, (. Average particle size ◦ 4 Ai m) 4 Weight And 8 parts by weight of an acrylic resin binder (manufactured by Mitsui Chemicals, Inc., trade name: SA-545, acid value 1.0) as an organic vehicle were added and 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 in a nitrogen atmosphere at 350 ° C. for 4 hours to thermally decompose the binder. Further, the degreased molded body was subjected to hot press firing 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 . Thereafter, after performing substrate cutting and surface grinding, a paste coating process was performed. In this step, nine kinds of samples were prepared in accordance with 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 μιη.

• Noble metal particles: 70% by weight of silver particles in total,

• Glass frit: 5 weight. /. (However, the base zinc borosilicate

80% by weight),

'Ethylcellulose as resin binder: 5% by weight,

'Butyl carbitol as solvent: 15 wt. / ₀ .

As the silver particles G 1 and G 2, four kinds shown in Table 1 were used in appropriate combination. Then, Samples 1 to 6 were positioned as Examples 1 to 6, and Samples 7, 8, and 9 were positioned as Comparative Example 1 and Test Examples 1 and 2. In the following, spherical silver particles using “Ag-126” manufactured by Shoei Chemical Industry Co., Ltd. were used as scaly silver particles. “Ag—520, Ag—530, Ag—540” (B, C, and D particles, respectively) manufactured by Sakae Chemical Industry Co., Ltd. were used. The “A particle” is a silver particle G1 having a mean particle size of 1.Οππ and a spherical shape (see FIG. 5 (a)).

All three types other than the A particles are flaky silver particles G2 (see Figs. 5 (b) to (d)). The average particle diameters of “B particles”, “C particles”, and “D particles” are 3.94 ^ m, 4.78 μm, and 7.73 jum, respectively. The aspect ratio (major axis / thickness) of these particles was about 7.8, 9.5, and 15, respectively.

Specifically, in Examples 1, 2, 4, and 5, two types of spherical silver particles G1 and flaky silver particles G2 were used, and the flaky silver particles G2 Two different ones (ie B particles and C particles) are used in combination.

In Example 3, two types of spherical silver particles G1 and flaky silver particles G2 were used, and only one flaky silver particle G2 (that is, only C particles) was used.

In Example 6, only the flaky silver particles G2 are used, and two flaky silver particles G2 having different particle diameters (that is, B particles and C particles) are used in combination. In other words, no spherical silver particles G1 are used for this.

In Comparative Example 1, the wiring resistance 10 was formed using a noble metal paste P1 containing only one kind of spherical silver particles G1 as in the related art. In Test Examples 1 and 2, although the wiring resistance 10 was formed using a noble metal paste P1 containing two types of silver particles G1 and G2, the average particle size was changed to flaky silver particles G2. Using large D particles. Table 1 shows the volume fraction (wt%) of the four particles in the wiring resistance 10.

[Comparison test and its results]

For each of the obtained nine types of samples, the wiring resistance 10 after the baking process was cut at an arbitrary position along the substrate thickness direction, and the cut surface was cut using a light microscope at 100 × magnification. I took a photo. Based on the enlarged photograph taken in this manner, the value of the area of the void portion / the cross-sectional area of the paste was measured, and this value was used as the void ratio (%) after firing. The results are shown in Table 1. The high void fraction (%) after firing means that the silver particles Gl and G2 are densely packed and the bonding area between the silver particles G1 and G2 is large. Do: The surface roughness (R a) of the wiring resistance 10 surface was measured in accordance with a conventional method using a surface shape measuring device (trade name: P-11, manufactured by KLA Tencor Inc.). See Table 1. The fact that the surface roughness is small and the surface is smooth means that the wiring resistance 10 has a uniform thickness, the resistance value is uniform, and the variation is small. A strength test was performed, and the tensile strength (kgf / 2 mmD) of the wiring resistance 10 was measured. Needless to say, if this value is large, the adhesion of the conductor pattern layer 10 is increased, and peeling is unlikely to occur.

As apparent from Table 1, the void ratio after firing in Comparative Example 1 was as high as 12% or more. On the other hand, in Example 3, it was confirmed that the void ratio after firing was as low as 9.8%. In Examples 1, 2, 4, 5, and 6, it was confirmed that the void ratio after firing was significantly lower than that of Comparative Example 1 and Test Examples 1 and 2. Above all, good results were obtained in Example 6, and then good results were obtained in Examples 1 and 4.

In Comparative Example 1, Test Examples 1 and 2, the surface roughness Ra was 1.Ομιη or more, whereas in each of Examples 1 to 6, it was lower than 1.0 m. Is confirmed Was. Above all, good results were obtained in Example 6, and then good results were obtained in Examples 1, 2, and 3.

In addition, when the wiring resistance 10 of each of Examples 1 to 6 was separately observed, no swelling was observed and there was no particular decrease in the adhesion.

In Comparative Example 1, the value of the tensile strength was as extremely low as about 3.5 kgf / 2 mm. On the other hand, in each of Examples 1 to 6, it was confirmed that a value almost twice or more of the comparative example was obtained. Above all, good results were obtained in Example 2, and then good results were obtained in Examples 1 and 6. From the above results, it is considered that the scaly particles have an effect of improving the tensile strength.

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

In Example 7, silicon nitride powder (average particle size 1. l / m) to 4 5 parts by weight, Y ₂ 0 ₃ (flat Hitoshitsubu径0. 4 μπ 20 parts by weight, Alpha 1 ₂ 0 ₃ (average particle size 0. 5 μπι) 1 5 parts by weight, S i 0 ₂ (average particle diameter 0. 5; xm) 20 parts by weight, accession Lil system with an organic vehicle resin by Sunda (manufactured by Mitsui Chemicals, Inc., trade name: SA — 54 5, acid value 1.0) 8 parts by weight were mixed The kneaded product obtained by uniformly kneading the mixture thus obtained was placed in a press mold and pressed to obtain a plate-shaped formed body. Was prepared.

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 1600 ° C. for 3 hours to obtain a silicon nitride substrate as the ceramic substrate 9. The pressure of the hot press was set at 150 kg / cm.

Thereafter, after the substrate was cut out and the surface was ground, a paste application step was performed. Here, as the noble metal paste P1, a sample having the following composition was used, and the thickness at the time of application was set to about 25, thereby preparing Sample 10.

• Noble metal particles: 56.6 parts by weight of silver particles G2,

10.3 parts by weight of palladium particles G1,

• oxide glass component:. S i O ^ S l 0 parts by weight, B: _0:, is 2.5 parts by weight,

Z nO is 5.6 parts by weight, heat 0 0.6 parts by weight, Ru_〇 ₂ 2.1 part by weight, • Resin binder: 3.4% by weight,

-Butyl carbitol as solvent: 17.9% by weight.

Here, as the “silver particles G 2”, flaky silver particles having an average particle size of 3.94 m (ie, the B particles) were used. As the “palladium particles Gl”, spherical palladium particles having an average particle diameter of 5.12 and ιη (Pd-215, manufactured by Shoei Chemical Industry) were used.

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 7 was completed. . The weight ratio of the two particles in the conductor pattern layer 10, that is, the ratio of the silver particles G 2: palladium particles G 1 was 55:15.

[Comparison test and its results]

With respect to the obtained sample of Example 7, the same comparative test as that of Examples 1 to 6 was performed. As a result, after firing, the void ratio was 7.8%, the surface roughness Ra was 0.7 μηι, and the tensile strength was 10.8 kgί2 mm.

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

(1) The wiring resistance 10 and the pad 10a of the above Examples 1 to 5 and 7 consist of spherical noble metal particles G1 and flaky noble metal particles G2. In addition, the wiring resistance 10 and the pad 10a of Example 6 described above consist only of the flaky noble metal particles G2. Therefore, it is considered that the noble metal particles G 2 (or G 1 and G 2) are more likely to be densely packed after baking, compared to a configuration including only the spherical noble metal particles G 1 (for example, Comparative Example 1). Can be Therefore, the void ratio at the wiring resistance 10 decreases, and the adhesion to the ceramic substrate 9 increases. On the other hand, there is point contact between the noble metal particles G 2 (or G 1 and G 2). Therefore, a remarkable decrease in the resistance value of the wiring resistance 10 is prevented, and the function as the resistor is not impaired.

(2) If the scale-like silver particles G 2 are made to have two different average particle diameters as in Examples 1, 2, 4, and 5, wirings having a tensile strength of 1 O kgf / 2 mm or more can be obtained. The resistance 10 can be obtained.

(3) As in Example 6 above, the flaky silver particles G 2 were divided into two types having different average particle sizes. If the spherical noble metal particles G 1 are not included at all, the void ratio can be made extremely low, and the adhesion can be remarkably improved.

(4) In each of Examples 1 to 7 of this embodiment, since the aluminum nitride substrate or the silicon nitride substrate is used as the ceramic substrate 9, the hot plate 3 having excellent heat resistance and thermal conductivity can be realized. it can.

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

• Instead of the aluminum nitride substrate used in the embodiment and a nitride ceramic substrate such as a silicon nitride substrate, for example, an oxide ceramic substrate such as an alumina substrate or a carbide ceramic substrate such as a silicon carbide substrate may be used. it can.

• The ceramic substrate 9 is not limited to a substrate manufactured through a press forming method, but may be a substrate manufactured through a sheet forming method using a doctor blade device, for example. When the sheet forming method is employed, for example, the wiring resistance 10 can be provided between the stacked sheets, so that the hot plate 3 for high temperature can be realized relatively easily.

• The conductor pattern layer is not limited to only the wiring resistance 10 and the pad 10a exemplified in the embodiment, but may be any other conductor pattern layer, that is, a conductor pattern layer that is not a heating resistor. Good.

• As a method of applying the noble metal paste P1 to the ceramic substrate 9, not only a screen printing method but also a stamping method, for example, can be adopted.

Claims

The scope of the claims

1. A hot plate comprising a ceramic substrate and a conductor layer, wherein the conductor layer is made of substantially scaly noble metal particles.

2. The hot plate according to claim 1, wherein the average particle diameter of the substantially scaly noble metal particles is 6 m or less.

3. The hot plate according to claim 1, wherein the substantially scaly noble metal particles are at least one selected from gold particles, silver particles, platinum particles, and palladium particles.

4. The hot plate according to any one of claims 1 to 3, wherein the aspect ratio of the major axis to the minor axis of the substantially scaly noble metal particles is 1.5 or more.

5. A hot plate comprising a ceramic substrate and a conductor layer, wherein the conductor layer is formed of substantially granular noble metal particles and substantially scaly noble metal particles.

6. The method according to claim 5, wherein the substantially granular noble metal particles have an average particle size of 3 μm or less, and the substantially scaly noble metal particles have an average particle size of 6 μm or less. Print plate.

7. The hot plate according to claim 5, wherein the substantially scaly noble metal particles are composed of two or more kinds of particles having different average particle diameters.

8. Five to twenty-five times of the substantially granular noble metal particles of the substantially granular noble metal particles The hotplate according to any one of claims 5 to 7, wherein the hotplate is included in the conductor layer.

9. Conductive paste consisting of roughly scaly noble metal particles, oxides and organic vehicles

10. Conductive paste consisting of substantially granular noble metal particles, almost scaly noble metal particles, oxides and organic vehicles.

11. The method according to claim 9, wherein the substantially scaly noble metal particles are at least one selected from gold particles, silver particles, platinum particles, and palladium particles. The conductive paste as described in the above.

12. The conductive paste according to any one of claims 9 to 11, wherein the substantially scaly noble metal particles are made of two or more kinds having different average particle diameters.

13. The conductive paste contains 5 to 25 times the substantially scaly noble metal particles 5 to 25 times the substantially granular noble metal particles, according to any one of claims 1 to 12. Conductive paste.

14. An average particle diameter of the substantially granular noble metal particles is 3 μm or less, and an average particle diameter of the substantially scaly noble metal particles is 6 μπι or less. 4. The conductive paste according to any one of 3.