JPH0786708A - Method of manufacturing ceramic circuit board - Google Patents

Abstract

PURPOSE:To provide the title manufacturing method of ceramic circuit board having excellent thermal shock resistance and capable of preventing the disconnection of a surface layer conductor. CONSTITUTION:In order to manufacture the title ceramic circuit board having a grazed film 2 on the surface of a ceramic board, the grazed film 2 is formed on the surface of a ceramic green sheet 100 and then a molded body 19 comprising the ceramic green sheet 100 and the grazed film 2 is siumultaneously baked. Besides, it is preferable that the surface of the molded body 19 is pressed with a parallel flat plate 6 before the molded body 19 is baked. At this time, as the ceramic green sheet 100, a low temperature sintered board sintered at the temperature not exceeding 1000 deg.C can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ceramics circuit board in which a glaze film for forming a thin film of a ferromagnetic material or the like is provided on a ceramics board.

[0002]

2. Description of the Related Art Conventionally, as a ceramic circuit board, there is one in which a glaze film 92 and a conductor circuit 95 are formed on the surface of an insulating ceramic board 91 as shown in FIG. In manufacturing the above-mentioned ceramic circuit board, the ceramic green sheet is fired to obtain a ceramic board, and then a glaze film and a conductor circuit are formed by printing on the surface of the ceramic board and fired again.

This ceramic circuit board is used as a magnetic sensor by forming a ferromagnetic film for magnetic detection on the glaze film 92, for example. Glaze film 9
As shown in FIG. 19, a ferromagnetic material such as a nickel alloy is deposited on the second layer 2 by sputtering or the like to form a ferromagnetic film 97. This allows the ceramic circuit board to be used as a magnetic sensor.

[0004]

However, the coefficient of thermal expansion of the ceramic substrate 91 is smaller than that of the glaze film 92. Therefore, as shown in FIG. 18, stress is applied to both during cooling after baking the glaze film.
Therefore, when thermal shock is applied to this ceramic circuit board, cracks 98 may occur in the glaze film 92. Further, the surface of the glaze film 92 needs a certain degree of surface smoothness in order to maintain the uniformity of the film thickness of the ferromagnetic material. To obtain this surface smoothness, the glaze film 92
Must be thick enough.

However, as shown in FIG. 19, when the glaze film 92 becomes thick, when the surface layer circuit 99 is formed between the ferromagnetic film 97 formed on the surface of the glaze film 92 and the conductor circuit 95, the surface layer circuit 99 is formed. A disconnection 999 occurs at the connection portion with the glaze film 92 at. Therefore, the signal of the ferromagnetic film 97 as the magnetic detector is not transmitted to the external terminal 94 connected to the conductor circuit 95. In view of the above conventional problems, the present invention is to provide a method for manufacturing a ceramic circuit board which is excellent in thermal shock resistance and can prevent disconnection of a surface layer circuit.

[0006]

According to a first aspect of the present invention, in a method for manufacturing a ceramic circuit board having a glaze film on the surface of a ceramic substrate, a glaze film is formed on the surface of a ceramic green sheet, and then the ceramic green sheet and the glaze film are formed. A method for manufacturing a ceramics circuit board is characterized in that the film is co-fired.

The most remarkable thing in the first invention is that
Ceramics green sheet (production sheet before firing)
And firing the glaze film at the same time. The ceramic green sheet is obtained by kneading a ceramic material with a mixture of a binder, a plasticizer, a solvent, etc., and molding this into a sheet by a doctor blade method or the like.

As the ceramic green sheet, a low temperature sintered substrate which can be sintered at a temperature of 1000 ° C. or lower can be used. As the low temperature sintered substrate, CaO-
A material obtained by adding alumina to Al ₂ O ₃ --SiO ₂ --B ₂ O ₃ system glass is used.

In addition to the glaze film, various types of circuit patterns can be formed on the inside or surface of the ceramic green sheet. Examples of the glaze layer, it is possible to use a PbO-B ₂ O ₃ -SiO ₂ based material such as glass.

The thickness of the glaze film is 10 to 50 μm.
Is preferred. When the thickness is less than 10 μm, the glaze material and the green sheet material react with each other, and the surface of the glaze film becomes rough. For example, when a ferromagnetic film is formed on the surface,
The ferromagnetic film becomes non-uniform and the wiring resistance is not constant.
On the other hand, when the thickness exceeds 50 μm, when a surface layer circuit is formed on the surfaces of the glaze film and the ceramic substrate, at the connecting portion between the surface of the glaze film and the surface of the ceramic substrate,
A disconnection may occur in the surface layer circuit. When a ferromagnetic film is formed on the surface of the glaze film, the surface roughness of the glaze film is preferably 0.001 to 0.500 μmRa. This improves the film thickness uniformity of the ferromagnetic film on the glaze film.

On the surface of the glaze film in the ceramic circuit board obtained by the present invention, a thin film of a ferromagnetic material for magnetic detection, Ni, Cr, Fe, Co, Mo, Ti, or an alloy thereof is formed. It can be used as a magnetic sensor or a circuit board with a thin film. As a method of forming the thin film, there are a sputtering technique, a vapor deposition technique and the like.

The second invention according to the present application is a method for manufacturing a ceramic circuit board having a glaze film on the surface of a ceramic substrate, in which a glaze film is formed on the surface of a ceramic green sheet to prepare a molded body, and then the molded body. The method of manufacturing a ceramics circuit board is characterized in that the surface of is pressed by a parallel plate and then the molded body is fired.

The most remarkable thing in the second invention is that
Prior to co-firing a molded body composed of a ceramic green sheet and a glaze film, the molded body is pressed by a parallel plate. The parallel plate has a smooth surface. The pressure applied to the compact by the parallel plate is 10 to 1
00 kg / cm ² is preferable. Others are the same as the above-mentioned first invention.

[0014]

FUNCTION AND EFFECT In the first invention, the ceramic green sheet and the glaze film are simultaneously fired.
At this time, the glass component of the glaze film diffuses into the ceramic substrate to form a glass diffusion layer. The glass diffusion layer has a coefficient of thermal expansion intermediate between those of the ceramic substrate and the glaze film. Therefore, the stress applied to the glaze film during cooling after co-firing is reduced. Therefore, a ceramic circuit board excellent in thermal shock resistance can be obtained without cracking in the glaze film due to thermal shock.

Further, in the above-mentioned second invention, the ceramic green sheet having the glaze film formed thereon is pressed by a parallel plate. Therefore, the glaze film gets inside the ceramic green sheet. Therefore, when this is fired, a ceramic circuit board with few surface steps between the ceramic board and the glaze film can be obtained.

Therefore, the surface layer circuit can be formed on the surfaces of the glaze film and the ceramics circuit board without disconnection. In addition, it has the same effect as the first invention. As described above, according to the present invention, it is possible to provide a method for manufacturing a ceramic circuit board which has excellent thermal shock resistance and can prevent the disconnection of the surface layer circuit.

[0017]

EXAMPLES Example 1 A ceramic circuit board according to the present invention will be described with reference to FIG. The ceramic circuit board 1 of this example has a glaze film 2 on the surface of the ceramic substrate 10. A glass diffusion layer 3 is formed between the glaze film 2 and the ceramic substrate 10.

In manufacturing the ceramic circuit board 1, first, CaO--Al ₂ O ₃ --SiO ₂ --B
_A ceramic material prepared by mixing 60% by weight of ₂ O ₃ based glass and 40% by weight of alumina with a binder, a plasticizer,
A solvent was added and kneaded, and this was molded by a doctor blade method to obtain a ceramic green sheet having a thickness of 0.3 mm. Further, the PbO-B ₂ O ₃ -SiO ₂ based glass to obtain a glaze paste.

Then, a 45 μm-thick glaze film was formed by printing on the surface of the ceramic green sheet by using the glaze paste to obtain a molded body. After that, the ceramic green sheet and glaze film are heated to 900 ° C.
At the same time. At this time, the glass component of the glaze film diffuses into the ceramic green sheet, and the glass diffusion layer 3 is formed. As a result, the ceramic circuit board 1 is obtained.

The coefficient of thermal expansion of the ceramic substrate 10 is 5.5 × 10 ^-6 / K. The thermal expansion coefficient of the glass diffusion layer 3 is 7.5 × 10 ⁻⁶ / K. The thermal expansion coefficient of the glaze film 2 is 9.5 × 10 ⁻⁶ / K. The surface roughness of the glaze film 2 is 0.03 μmRa.

Next, the function and effect of this example will be described.
In this example, when the ceramic green sheet and the glaze film are co-fired, the glass diffusion layer 3 having a coefficient of thermal expansion intermediate between the two is formed. Therefore, the stress applied to the glaze film 2 at the time of cooling after the simultaneous firing is reduced. Therefore, it is possible to prevent cracks from being generated in the glaze film 2. The surface of the glaze film 2 is smooth. Therefore, the ferromagnetic film for magnetic detection can be made to have a uniform film thickness on the surface of the glaze film 2, and it can be used as a magnetic sensor.

Example 2 In the ceramic circuit board of this example, as shown in FIG. 2, the glaze film 2 and the conductor circuit 51 are provided on the upper surface side of the ceramic board 10. The glaze film 2 and the conductor circuit 51 are embedded inside the ceramic substrate 10. Further, as shown in FIG. 3, the step H between the glaze film 2 and the ceramic substrate 10 is 4 μm. A glass diffusion layer 3 is formed between the glaze film 2 and the ceramic substrate 10. The glaze film 2 has 45
The thickness is μm, and the surface roughness is 0.03 μmRa.

In manufacturing the ceramic circuit board 1, first, the glaze film 2 and the conductor circuit are printed on the surface of the ceramic green sheet to form a molded body. Next, as shown in FIG. 4, the molded body 19 is placed on the parallel plate 4 for the lower mold. Next, the parallel plate 6 for the upper mold is placed on the upper surface side of the molded body 19. Next, the surface of the compact 19 is pressed by the parallel plates 4 and 6.

At this time, the glaze film 2 enters the inside of the ceramic green sheet 100, and the step difference between the glaze film 2 and the ceramic green sheet 100 is reduced. Then, the molded body is fired at 900 ° C. At this time, the glass component in the glaze film is diffused in the ceramic substrate 10 to form the glass diffusion layer 3. As a result, the ceramic circuit board 1 is obtained.

The cross-sectional structure structure near the surface of the ceramic circuit board 1 obtained by the above manufacturing method is shown in the micrograph of FIG. 6 (magnification: 1000 times). In the figure, a glass diffusion layer 3 in which the glass component in the glaze film 2 has diffused can be seen between the ceramic substrate 10 and the ceramic green sheet 2. Others are the same as those in the first embodiment.

Next, the function and effect of this example will be described. In this example, as shown in FIG. 4, the ceramic green sheet 100 having the glaze film 2 formed thereon is pressed by the parallel plates 4 and 6. At this time, the glaze film 2 enters the inside of the ceramic green sheet 100. Therefore, when this is fired, the ceramic circuit board 1 having few surface steps can be obtained. Therefore, as shown in FIG. 5, a thin surface layer circuit 5 is formed on the surface of the ceramic circuit board 1.
0 can be formed without breaking. In addition, the same effect as that of the first embodiment can be obtained.

Example 3 A ceramic circuit board of this example has a structure as shown in FIG.
It is a multilayer board A in which a plurality of ceramic substrates 11 to 16 are laminated. A glaze film 2 is provided on the surface of the uppermost ceramic substrate 11. A glass diffusion layer 3 is formed between the ceramic substrate 11 and the glaze film 2. Further, via holes 19 filled with the conductor circuit 51 and the conductor 5 are formed in each of the ceramic substrates 11 to 16.

In manufacturing the multilayer board A, first, as shown in FIG. 8, via holes 19 are formed by filling the six ceramic green sheets 111 to 116 with the conductor circuits 51 and the conductors 5. Next, these ceramic green sheets are laminated and thermocompression bonded using a parallel plate. Next, as shown in FIG. 9, the glaze film 2 is formed by printing on the surface of the uppermost ceramic green sheet 111. Then, this laminated body is co-fired at 900 ° C.

At this time, the ceramic green sheets 111 to 116 are sintered to obtain the ceramic substrates 11 to 16 shown in FIG. 7, and the glass component of the glaze film 2 diffuses into the ceramic substrate 11 to cause the glass diffusion. Layer 3 is formed. Thereby, the multilayer board A is obtained. Others are the same as in the first embodiment.

Example 4 The ceramic circuit board of this example has a structure as shown in FIG.
Multilayer board B in which six ceramic substrates 11 to 16 are laminated
Is. The glaze film 2 is provided on the surface of the uppermost ceramic substrate 11. The glaze film 2 is embedded inside the ceramic substrate 11. A glass diffusion layer 3 is provided between the ceramic substrate 11 and the glaze film 2.
Are formed. In addition, a via hole 19 filled with the inner layer circuit 51 and the conductor 5 is formed inside the multilayer board B.

In manufacturing the multilayer board B, first, as shown in FIG. 11, six ceramic green sheets 111 to 116 are formed with via holes 19 filled with the conductor circuits 51 and the conductors 5. Further, the glaze film 2 is formed by printing on the uppermost ceramic green sheet 111. Next, the ceramic green sheets 111 to 116 are laminated and thermocompression bonded using a parallel plate.

At this time, as shown in FIG. 12, the glaze film 2 enters the inside of the ceramic green sheet 111. Then, when the pressure-bonded body is simultaneously fired at 900 ° C., the glass diffusion layer 3 is formed between the ceramic substrate 11 and the glaze film 2. As a result, the multilayer board B is obtained. Others are the same as those in the second embodiment.

Example 5 In this example, the ceramic circuit boards (Sample 1 to Sample 4) according to the present invention were examined for cracks in the glaze film, surface roughness, and breakage of the surface layer circuit due to thermal cycles. Sample 1 is the multilayer board A of Example 3 shown in FIG. Samples 2 to 4 are obtained by changing the thickness of the glaze film and the level difference between the glaze film and the ceramic substrate in the multilayer board B of Example 4 shown in FIG.

For comparison, as shown in FIG. 13, a multi-layered board C of a ceramic circuit board was produced in which the glaze films 2 having different thicknesses were formed by printing on the surface of the fired ceramics board (Samples 5 to 5). 8). As shown in FIG. 14, a conductor circuit 51 and a surface layer circuit 50 were formed on the surface of each of the ceramic circuit boards of Samples 1 to 7 by a photolithography technique. The surface layer circuit 50 is in contact with the ferromagnetic film 7 and the conductor circuit 51 formed on the surface of the glaze film 2.

The results of the above survey are shown in Table 1. In the table, “crack due to thermal cycle” means 25 to 230.
The crack occurrence rate of the glaze film was measured when a temperature change of 10 cycles was performed between 0 ° C. The “breakage of the thin film” means breakage of the thin ferromagnetic film 7 caused by the rough surface of the glaze film.

As a result of the investigation, in Samples 1 to 4, cracks did not occur in the glaze film due to the heat cycle test.
It is considered that this is because the glass diffusion layer formed between the glaze film and the ceramic substrate alleviates the stress on the glaze film during cooling.

In the sample 1, as shown in FIG. 15, the glass diffusion layer 3 is provided between the glaze film 2 and the ceramic substrate 11.
Due to the formation of cracks, no crack was generated in the glaze film 2 by the thermal cycle test. On the other hand, since the step difference between the glaze film and the ceramic substrate is large, the disconnection 509 of the surface layer circuit 50 occurred at the joint between the glaze film 2 and the surface layer circuit 50. However, the defect rate (craze of the glaze film and disconnection of the surface layer circuit) was significantly reduced from 6.1% (Sample 7) to 1.8% (Sample 1).

In Samples 2 to 4, disconnection between the glaze film and the surface layer circuit did not occur. This is as shown in FIG.
The step H between the ceramic substrate 11 and the glaze film 2 is 7μ
It is considered that this is because the surface layer circuit adheres to the inclined portion of the glaze film 2 while maintaining a sufficient thickness because the surface layer circuit is as small as m or less. On the other hand, in Samples 5 to 7, not only cracking of the glaze film 2 but also disconnection between the glaze film 2 and the surface layer circuit 50 occurred. Further, since the sample 8 had a thin glaze film 2, the surface thereof was rough, and the thin ferromagnetic film 7 formed on the glaze film 2 was broken.

[0039]

[Table 1]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a ceramics circuit board according to a first embodiment.

FIG. 2 is a sectional view of a ceramics circuit board according to a second embodiment.

FIG. 3 is a cross-sectional view near the surface of the ceramic circuit board of Example 2.

FIG. 4 is an explanatory view showing a method for manufacturing a ceramics circuit board according to a second embodiment.

FIG. 5 is a cross-sectional view of a ceramics circuit board having a surface layer circuit formed on its surface in Example 2.

FIG. 6 is a cross-sectional photomicrograph (magnification: 500 times) showing the structure structure near the surface of the ceramic circuit board of Example 2.

FIG. 7 is a ceramic circuit board of Example 3 (laminated plate A).
Sectional view of.

FIG. 8 is an explanatory diagram showing a method for manufacturing a ceramics circuit board according to a third embodiment.

9 is an explanatory view of the manufacturing process following FIG. 8. FIG.

FIG. 10 is a cross-sectional view of a ceramics circuit board (laminated board B) of Example 4.

FIG. 11 is an explanatory diagram showing a method for manufacturing a ceramics circuit board of Example 4.

FIG. 12 is an explanatory view of the manufacturing process following FIG. 11.

FIG. 13 is a sectional view of a ceramic circuit board (laminated plate C) of Samples 5 to 8 in Example 5.

FIG. 14 is a plan view of a ceramics circuit board having a surface layer circuit formed on the surface thereof in Example 5;

FIG. 15 is a cross-sectional view of the ceramic circuit board of sample 1 according to the fifth embodiment.

16 is a cross-sectional view of the ceramic circuit boards of Samples 2 to 4 in Example 5. FIG.

FIG. 17 is a cross-sectional view of a conventional ceramic circuit board.

FIG. 18 is an explanatory diagram illustrating a problem of the conventional example.

FIG. 19 is an explanatory diagram illustrating another problem of the conventional example.

[Explanation of symbols]

1. ． ． Ceramic circuit board, 10-16. ． ． Ceramic substrate, 100, 111-116. ． ． Ceramics green sheet, 2. ． ． Glaze film, 3. ． ． Glass diffusion layer, 4, 6. ． ． Parallel plate, 50. ． ． Surface layer circuit, 51. ． ． Conductor circuit, 7. ． ． Ferromagnetic film,

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H05K 3/46 H 6921-4E // H01L 43/02 Z

Claims (4)

[Claims] 1. A method for manufacturing a ceramic circuit board having a glaze film on the surface of a ceramic substrate, wherein a glaze film is formed on the surface of a ceramic green sheet, and then the ceramic green sheet and the glaze film are co-fired. Ceramic circuit board manufacturing method. 2. A method of manufacturing a ceramic circuit board having a glaze film on the surface of a ceramic substrate, wherein a glaze film is formed on the surface of a ceramic green sheet to prepare a molded body, and then the surface of the molded body is formed by a parallel plate. A method for manufacturing a ceramics circuit board, which comprises pressurizing and then firing the molded body. 3. The method for manufacturing a ceramic circuit board according to claim 1, wherein the ceramic green sheet is a low temperature sintered substrate that is sintered at 1000 ° C. or lower. 4. The method of manufacturing a ceramic circuit board according to claim 1, wherein the glaze film is a material that is sintered at 1000 ° C. or lower.