JPH04291994A - Fabrication of composite ceramic circuit board - Google Patents

Abstract

PURPOSE:To ensure a predetermined performance over a long period of time with sufficient interlayer contact property and without causing interlayer separation, warp, damage, etc., of a board, by pouring slurry onto a carrier film in succession and laminating layers into a multilayered structure. CONSTITUTION:A green sheet 4 is formed by pouring slurry 2 onto a carrier film 1 using a doctor blade 3 and drying the same. Then, a laminate green sheet is formed by again pouring slurry 2' onto the green sheet 4, and molding and drying the same. Further, slurry is poured onto the laminate green sheet desired number of times and hereby a green sheet is formed on the laminate green sheet for every layer to yield a multilayered structure. The multilayered green sheet is molded into a predetermined outer configuration and a wiring pattern and a via hole are formed, and thereafter the resulting green sheet is laminated with other green sheets and baked to ensure a composite ceramic circuit board.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a composite ceramic circuit board, for example, a circuit board mounted on an electronic device such as a computer, and particularly to a method for manufacturing a composite ceramic circuit board formed by laminating different materials.

0002

2. Description of the Related Art Ceramic circuit boards are widely used in various electronic devices because they are suitable for mounting LSIs. Particularly in the field of computers, there is a demand for circuit boards that can reduce the size of devices and increase processing speed. Against this background, functional ceramic circuit boards have appeared, such as circuit boards that incorporate passive elements such as resistors and capacitors, and PGA type circuit boards that have cavities for housing the elements. ing.

Particularly recently, attempts have been made to obtain functional composite ceramic circuit boards by laminating green sheets of different materials, ie, having different compositions, and firing them simultaneously. Conventionally, such composite ceramic circuit boards have been manufactured by individually producing multiple green sheets with different compositions on different carrier films using a carrier film method, and then integrating them during lamination and firing. .

0004

[Problem to be Solved by the Invention] However, if a plurality of green sheets with different compositions are individually produced,
In the method of laminating and firing multiple green sheets that have been individually manufactured, it is difficult to obtain sufficient adhesion between the layers. During firing, cooling, use, etc., the effects of thermal stress, such as mismatch in firing shrinkage rate and mismatch in thermal expansion coefficient, become noticeable.

[0005] For example, the influence of thermal stress such as the above-mentioned mismatch in firing shrinkage rate and mismatch in thermal expansion coefficient causes delamination, warping, and destruction of the substrate. In other words, in the conventional manufacturing method of composite ceramic circuit boards, there is a problem in that the resulting board is prone to delamination and warping, making it impossible to efficiently manufacture composite ceramic circuit boards that exhibit the desired functions. There's a problem.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a material with sufficient adhesion between layers to prevent delamination, warping or destruction of the substrate, etc.
Therefore, it is an object of the present invention to provide a method that can efficiently manufacture a composite ceramic circuit board that exhibits desired performance over a long period of time.

[0007]

[Means for Solving the Problems] The gist of the present invention to achieve the above object is to provide a method for manufacturing a composite ceramic circuit board in which a plurality of green sheets made of different materials are laminated and then fired. In the green sheet, after a first slurry made of a first ceramic composition is poured onto a carrier film to form a lower green sheet, a second slurry made of a second ceramic composition is poured onto the lower green sheet. A multilayer green sheet is formed by pouring the above-mentioned ceramic composition into a layer, laminating an upper layer green sheet, and then peeling it off from the carrier film, in which either the first ceramic composition or the second ceramic composition is made of glass/ceramic. A method of manufacturing a composite ceramic circuit board, characterized in that the other is a high dielectric ceramic, using a plurality of ceramic slurries, and applying one of the plurality of ceramic slurries on a green sheet by a doctor blade method. The method for manufacturing the above-mentioned composite ceramic circuit board includes the step of repeating the step of pouring and forming a green sheet laminate a desired number of times to form a multilayer green sheet of three or more layers. and then firing, the method further comprising forming a glass coating on the exposed portion of the porous ceramic layer on the side surface of the circuit board. It's a method.

[0008] The present invention will be explained below by dividing into a process for manufacturing a multilayer green sheet and a process for manufacturing a composite ceramic circuit board. - Manufacturing process of multilayer green sheet - In the manufacturing process of multilayer green sheet in the present invention, first, a slurry is poured onto a carrier film, and the slurry is molded to produce a green sheet.

[0009] As the above-mentioned carrier film, any of those conventionally used in the production of green sheets, such as a polyester film coated with silicone, can be suitably used. The slurry poured onto the carrier film is prepared, for example, by kneading a mixture of ceramic powder, glass powder, etc., usually adding at least a binder, a plasticizer, and a solvent.

For example, as shown in FIG. 1, a doctor blade 3 can be suitably used to pour the slurry 2 onto the carrier film 1. By using the doctor blade 3, the slurry is poured onto the sheet. Can be poured. After the slurry is poured onto the carrier film in this manner, it is usually dried to form a green sheet.

In the method of the present invention, after forming the green sheet on the carrier film as described above,
The slurry is poured onto this green sheet again and the green sheets are laminated. The state is shown in FIG. In addition,
In FIG. 1, 4 is a green sheet formed on the carrier film 1 as described above. The slurry 2' used at this time may have the same composition as the slurry 2 poured onto the carrier film 1, or may have a different composition. If slurry of the same composition is used, thicker green sheets can be obtained,
By using slurries with different compositions, composite green sheets of different materials can be obtained. For example, if a slurry with a barium titanate composition is poured onto a green sheet with a glass-ceramic composition, a green sheet with a barium titanate composition will be laminated on a green sheet with a glass-ceramic composition, and a green sheet with a glass-ceramic composition will be stacked on top of the green sheet with a glass-ceramic composition. By pouring a glass-ceramic composition slurry on top, a thick laminated green sheet with a glass-ceramic composition can be obtained. Also, for example, glass
It is also possible to pour a slurry of a glass-ceramic composition in which only the binder component is in excess on a green sheet of a ceramic composition.

[0012] In this way, the slurry is poured onto the green sheet on the carrier film, and after shaping, it is usually dried to form a laminated green sheet. In the method of the present invention, the slurry is further poured onto the laminated green sheet a desired number of times to form a green sheet layer by layer on the laminated green sheet to form a multilayered green sheet.

[0013] Here, the method for forming each layer is the same as the method for forming the above-mentioned green sheet laminated on the green sheet formed on the carrier film, and the composition of the slurry used for forming each layer is different. may be the same or may be the same. Note that the number of layers to be laminated can be appropriately determined as necessary. Moreover, the thickness of each layer is usually 30 to 300 μm.

The multilayer green sheet produced as described above is, for example, formed into a predetermined external shape, further formed with wiring patterns and via holes, and then laminated with other green sheets to form a composite ceramic circuit board. It can be suitably used to form. - Manufacturing process of composite ceramic circuit board - In the method of manufacturing a composite ceramic circuit board of the present invention, when laminating a plurality of composite green sheets made of different materials, a porous ceramic layer is formed between adjacent composite green sheet layers of different materials. Interpose a green sheet for this purpose.

[0015] By interposing this green sheet for forming a porous ceramic layer between adjacent composite green sheet layers of different materials, it is possible to prevent warpage, breakage, etc. that occur between layers of different materials due to thermal stress during firing, cooling, and use. It can be relaxed. The porosity of a porous ceramic layer having such an effect after firing is usually 10% or more, preferably 30% or more.

[0016] This porous ceramic layer can be formed using, for example, a slurry having a glass-ceramic composition, and more specifically, alumina (Al2O3).
It can be formed using a slurry having a borosilicate glass composition. The porosity of the porous ceramic layer can be determined by adjusting the blending ratio of alumina (Al2 O3) and borosilicate glass, for example, when using the slurry having the above-mentioned alumina (Al2 O3)/borosilicate glass composition. It can be determined as appropriate. Specifically, if the blending ratio of borosilicate glass is reduced, sintering of the layer will be hindered, so the porosity can be increased.

In the method of the present invention, the porous ceramic layer described above is formed between layers of different materials, and a composite ceramic circuit board is manufactured as follows. First, a plurality of single-layer or composite green sheets made of different materials and a green sheet for forming a porous ceramic layer are produced. Each green sheet may be produced individually by employing, for example, a carrier film method, but it can also be produced in the form of a laminate by sequentially pouring slurry using the multilayer green sheet production method described above.

[0018] Here, the combination of green sheets made of different materials is not particularly limited as long as it is a combination of green sheets of different materials or different compositions; for example, a green sheet with a glass/ceramic composition and a barium titanate composition. For example, a combination with a green sheet may be used. Note that normally, a via is formed in each green sheet, and a wiring pattern is formed on the surface.

The green sheets are laminated in the order in which the green sheets for forming a porous ceramic layer are formed between layers of different materials. In the method of the present invention, a composite ceramic circuit board can be obtained by firing the laminate obtained as described above. The firing temperature at this time is usually about 900 to 1000°C, and the firing time is usually about 1 to 5 hours.

[0020] The composite ceramic circuit board obtained in the above manner has a porous ceramic layer exposed on its side surface, and this exposed portion has poor water resistance and moisture resistance, so that moisture may enter through this exposed portion. It is desirable to form a glass coating on the exposed portion of the porous ceramic layer on the side surface of the circuit board, since the dielectric material in the substrate is eroded by moisture and the like, leading to deterioration of the substrate characteristics.

[0021] This glass coating is formed by applying a glaze glass paste to the entire side surface of the composite ceramic circuit board or at least to the exposed portion of the porous ceramic layer exposed on the side surface of the composite ceramic circuit board, or by spraying it. The glaze glass layer can be formed by forming the glaze glass layer and then firing the glaze glass layer. Note that the firing conditions at this time are usually a temperature of about 500 to 800°C and a time of 15 to 3
It takes about 0 minutes. Moreover, the thickness of the glass film formed in this way is usually about 10 to 30 μm.

[0022]

EXAMPLES Examples of the present invention will be shown below to explain the present invention more specifically. (Example 1) Alumina (Al2O3
), borosilicate glass having an average particle size of 4 μm was prepared so that the weight ratio of (alumina):(borosilicate glass) was 1:1 to obtain a mixed powder. Next, 10 parts by weight of an acrylic binder, 100 parts by weight of acetone, and 4 parts by weight of DBP (dibutyl phthalate) were added to this mixed powder, and the mixture was kneaded in a ball mill for 20 hours to form a slurry. The obtained slurry was poured onto a carrier film using a doctor blade, and then left at room temperature for 2 hours to dry, thereby obtaining a green sheet of alumina/glass composition having a thickness of 300 μm.

[0023] Next, a slurry having a barium titanate composition was applied onto this green sheet having alumina-glass composition.
The mixture was poured using a doctor blade, and then allowed to stand at room temperature for 2 hours to dry. Green sheets having a barium titanate composition having a thickness of 80 μm were laminated to obtain a multilayer green sheet. Here, the slurry having a barium titanate composition is a mixed powder obtained by adding 2 mol% of lithium carbonate with an average particle size of 4 μm to barium titanate with an average particle size of 1 μm, 10 parts by weight of an acrylic binder, and 100 parts by weight of acetone. parts by weight and 4 parts by weight of DBP (dibutyl phthalate) were added and kneaded for 20 hours in a ball mill.

[0024] Using two composite multilayer green sheets thus produced, four single-layer green sheets having an alumina/glass composition and one single-layer green sheet having a barium titanate composition produced by the carrier film method,
Lamination was carried out as shown in FIG. 2 under conditions of a lamination pressure of 10 MPa and a temperature of 100°C. In FIG. 2, 5 is a composite multilayer green sheet, 5a is a green sheet with alumina/glass composition, 5b is a green sheet with barium titanate composition, 6
7 is a single-layer green sheet having an alumina/glass composition produced by a carrier film method, 7 is a single-layer green sheet having a barium titanate composition produced by a carrier film method, and 8 is a wiring pattern. Note that a punch was used to shape each green sheet into a predetermined shape and to form via holes. Further, via holes (not shown) were filled with copper paste, and the wiring pattern 8 was formed by screen printing using the copper paste.

The thus produced laminate was fired in a nitrogen atmosphere at a temperature of 1000° C. for 4 hours to obtain a composite ceramic circuit board. Fifty composite ceramic circuit boards were produced in the same manner, and the warpage rate and failure (
When the occurrence rate of warping (delamination) was determined, the occurrence rate of warping was 1%, and the incidence of fracture (delamination) was 0%. (Comparative Example 1) Fifty composite ceramic circuit boards were manufactured in the same manner as in Example 1, except that the multilayer green sheets were individually produced for each layer by the conventional carrier film method and then laminated. was manufactured, and the rate of occurrence of warping and occurrence of breakage (delami) was investigated, and the rate of occurrence of warpage was 30%, and the rate of breakage (delami) was 20%. (Example 2) Preparation of green sheet with alumina/glass composition Alumina (Al2O3) with an average particle size of 5 μm and borosilicate glass with an average particle size of 4 μm were mixed at a weight ratio of (alumina):(borosilicate glass) of 1:1. A green sheet having a thickness of 300 μm and having an alumina/glass composition was produced by the carrier film method in the same manner as in Example 1 using the mixed powder prepared in the ratio of . Preparation of a green sheet for forming a porous ceramic layer In the preparation of a green sheet with the above alumina/glass composition, alumina (Al2O3) with an average particle size of 5 μm and borosilicate glass with an average particle size of 4 μm were mixed in a weight ratio of 1:1. Except that instead of the mixed powder prepared by mixing alumina (Al2O3) with an average particle size of 5 μm and borosilicate glass with an average particle size of 4 μm in a weight ratio of 4:1, a mixed powder was used. A green sheet for forming a porous ceramic layer having an estimated porosity of 50% after firing and a thickness of 300 μm was prepared in the same manner as in the preparation of the green sheet having the above alumina/glass composition. Preparation of a green sheet having a barium titanate composition The procedure was carried out in the same manner as in Example 1 using a mixed powder obtained by adding 2 mol % of lithium carbonate having an average particle size of 4 μm to barium titanate having an average particle size of 1 μm. A green sheet having a barium titanate composition and having a thickness of 80 μm was prepared. Manufacture of composite ceramic circuit board Each of the three types of single-layer green sheets produced as described above is formed into a predetermined external shape, and after forming vias and wiring patterns on each green sheet, alignment is performed. , laminated under conditions of temperature 100℃ and pressure 10MPa, and laminated under conditions of temperature 1000℃ in nitrogen atmosphere.
After baking for an hour, apply a glaze glass paste on the side surface, and then heat it in a nitrogen atmosphere at a temperature of 600℃ for 3 hours.
The composite ceramic circuit board 10 shown in FIG. 3 was obtained by firing for 0 minutes to form a glass film. In FIG. 3, 11 is an alumina glass layer, 12 is a porous ceramic layer, 1
3 is a barium titanate layer, 14 is a glass coating, 1
5 is a wiring pattern, and 20 is a resistor.

Fifty composite ceramic circuit boards were produced in the same manner, and the warpage incidence and breakage (delami) occurrence rate were determined. The results are shown in Table 1. In addition, this composite ceramic circuit board was used as an R. H. The dielectric constant and insulation resistance value of the dielectric material after being left in a 90% humidity environment were determined. The results are shown in Table 2.

[0027]

[Table 1]

[0028]

[Table 2]

(Example 3) The same procedure as in Example 2 was carried out except that the porosity of the porous ceramic after firing was changed from 50% to 10%. The results are shown in Table 1. (Example 4) The same procedure as in Example 2 was carried out except that the porosity of the porous ceramic after firing was changed from 50% to 20%.

The results are shown in Table 1. (Example 5) The same procedure as in Example 2 was carried out except that the porosity of the porous ceramic after firing was changed from 50% to 40%. The results are shown in Table 1. (Comparative Example 2) A composite ceramic circuit board was manufactured in the same manner as in Example 2 except that the porous ceramic layer was not formed.

[0031] The occurrence rate of warpage and the incidence of fracture were determined for this composite ceramic circuit board. The results are shown in Table 1. (Comparative Example 3) A composite ceramic circuit board was manufactured in the same manner as in Example 2 except that the glass coating was not formed.

[0032] This composite ceramic circuit board was subjected to R.I. H.
The dielectric constant and insulation resistance value of the dielectric material were determined after being left in a 90% humidity environment for a certain period of time. The results are shown in Table 2.

[0033]

[Effects of the Invention] According to the present invention, since the slurry is sequentially poured and each layer is laminated to form a multilayer structure, the adhesion between the layers is sufficient and there is no possibility of delamination or warping, so that the desired function can be achieved. It is possible to provide a method for manufacturing a composite ceramic circuit board that can efficiently obtain a multilayer ceramic circuit board or a composite ceramic circuit board that exhibits the following properties.

Further, according to the present invention, since the layers of different materials are laminated by forming a porous ceramic layer between the layers of different materials, warpage due to thermal stress between the layers of different materials during firing, cooling, and use is avoided. It is possible to provide a method for manufacturing a composite ceramic circuit board that can efficiently obtain a composite ceramic circuit board that does not suffer from damage or destruction. Furthermore, if a glass coating is formed on the exposed part of the porous ceramic layer exposed on the side surface of the circuit board, a composite ceramic circuit board that has the above advantages and maintains the desired characteristics over a long period of time without being affected by moisture etc. Provided is a method for manufacturing a composite ceramic circuit board that can efficiently obtain the following.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the process of forming a multilayer green sheet used in the present invention.

FIG. 2 is a schematic explanatory diagram showing a cross section of a composite ceramic circuit board manufactured in this example during a process.

FIG. 3 is a schematic explanatory diagram showing a cross section of another composite ceramic circuit board manufactured in this example.

[Explanation of symbols]

1...Carrier film 2,2'...Slurry 4...Green sheet 5...Multilayer green sheet 10...Composite ceramic circuit board 12...Porous ceramic layer 14...Glass coating

Claims (4)

[Claims] 1. A method for manufacturing a composite ceramic circuit board in which a plurality of green sheets made of different materials are laminated and then fired, wherein at least one green sheet has a first layer made of a first ceramic composition on a carrier film. After pouring the slurry to form a lower green sheet, pouring a second slurry made of a second ceramic composition onto the lower green sheet to laminate the upper green sheet, and then peeling it off from the carrier film. A composite ceramic, which is a multilayer green sheet formed by a multilayer green sheet, wherein one of the first ceramic composition and the second ceramic composition is a glass ceramic, and the other is a high dielectric ceramic. Method of manufacturing circuit boards. [Claim 2] Using a plurality of ceramic slurries,
2. The method according to claim 1, further comprising the step of forming a multilayer green sheet having three or more layers by repeating the step of pouring any one of the plurality of ceramic slurries onto the green sheet by a doctor blade method to form a green sheet laminate a desired number of times. A method for manufacturing a composite ceramic circuit board. 3. A method for manufacturing a composite ceramic circuit board in which a plurality of green sheets made of different materials are laminated and then fired, characterized by forming a porous ceramic layer between adjacent layers of different materials, and then firing. A method for manufacturing a composite ceramic circuit board. 4. A glass coating is formed on an exposed portion of the porous ceramic layer on a side surface of the circuit board.
The method for manufacturing the composite ceramic circuit board described above.