JPH0217330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ceramic substrate with a novel shape and a method for manufacturing the same. Furthermore, in detail, at least 1
The present invention relates to a ceramic substrate having two smooth curved edges.

[Prior art] Conventional ceramic substrates are generally manufactured using three methods: tape molding, extrusion molding, and press molding.
manufactured by one of two manufacturing methods.

In the tape molding method, a green tape is obtained by uniformly applying a slurry obtained by mixing ceramic powder, a binder, and a solvent onto a carrier tape using a doctor blade and drying it.
Thereafter, it is cut into a desired shape by press punching and fired to obtain a ceramic substrate.

In the extrusion molding method, ceramic powder, a binder, and a solvent are kneaded, and the potted clay is extruded through a rectangular mouthpiece and dried to obtain a green sheet. The subsequent processing steps are the same as for the tape molding method.

In the press molding method, ceramic powder, binder, and solvent are mixed, granulated into uniform secondary particles using a spray dryer, etc., and then filled into a press mold and molded under pressure to obtain a molded product. . The processing steps after firing are the same as the tape molding method.

The above three methods have sufficient surface smoothness when only the upper and lower surfaces of the ceramic substrate are used. However, recent computers, communications,
Since high-density wiring is strongly required in many fields such as consumer electronics, it is desirable to use not only the top and bottom surfaces of ceramic substrates, but also the end surfaces as wiring surfaces. There is a point. First, in the tape molding and extrusion molding methods, the edge surface of the substrate corresponds to the punched cut surface of the green tape, and the surface properties are extremely rough and will not be improved by subsequent firing. . In the press molding method, the end surface of the substrate corresponds to the side surface of the press mold, and the end surface itself has good properties, but
In many cases, there are sharp protrusions called burrs at the corners of the substrate surface and end faces due to the clearance between the lower and upper molds of the press mold.

[Problems to be Solved by the Invention] An object of the present invention is to make it possible to utilize end surfaces that are hardly used as described above. That is, an object of the present invention is to provide a ceramic substrate having a smooth curved edge that allows a conductive layer to be formed also on the edge surface of the substrate. As mentioned above, with conventional ceramic substrates,
It was not possible to directly manufacture a substrate with a smooth end surface. Furthermore, it is extremely difficult to obtain a level of smoothness that allows a conductor layer to be directly formed by polishing the end face of a ceramic substrate made by conventional methods, and it takes a great deal of effort to obtain sufficient smoothness. is necessary. When polishing the side surface with a flat whetstone, for example, there are discontinuous corners because the surface is composed of many planes, and there is a high possibility of wire breakage when forming conductors.
Lacking reliability. Furthermore, even when a grindstone with a curved surface is brought in, reliability is similarly lacking because there are discontinuous angles between the flat surface and the end surface due to variations in the thickness during green sheet formation.

There is a method of forming a glass layer to eliminate discontinuous corners caused by polishing, but since this method also makes the glass layer thinner at the corners, it is recommended to form a thicker glass glaze layer to be safe. It is customary to do so. However, since the glass glaze layer has low thermal conductivity, when this end face is used as a head for a thermal printer, for example, the glass glaze layer is thick and causes trailing during printing, making it difficult to increase the speed. There are problems such as difficulty in responding to these demands. In order to solve these problems, the ceramic substrate of the present invention was invented.

[Means for solving the problems] The present invention involves forming a ceramic green sheet, bending the green sheet, joining the green sheet,
A ceramic substrate having a curved surface manufactured by firing a green sheet molded body whose bent portion forms a curved surface, and a ceramic substrate having a curved surface produced by molding the ceramic green sheet, bending and joining the green sheet, and manufacturing the ceramic substrate having the bent portion forming a curved surface. By firing the green sheet molded body forming the
This is a method for manufacturing a ceramic substrate with smooth curved edges.

The present invention provides a novel shape for ceramic substrates. This is a ceramic substrate that has a smooth curved surface on at least one end, thereby making it possible to obtain a continuous electrical connection even to the end surface of the substrate.

In this specification, "ceramic substrate" refers to inorganic oxides and inorganic powders such as alumina, silica, magnesia, talc, kaolin, silica, and calcium carbonate, on which electrical products and circuits are mounted. Alternatively, it refers to a product obtained by molding the powder of the mixture into a predetermined shape and firing it.

Furthermore, the term "green sheet" refers to a preform of a ceramic substrate that has just been molded before firing.

The present invention is a ceramic substrate 1 having a structure as shown in FIG. 1b. That is, it is a ceramic substrate having a smooth curved surface on at least one end surface obtained by firing a ceramic molded body having a curved end surface on at least one end portion, which is made of a bent ceramic green sheet 1. By firing a ceramic green sheet structure with a new shape, it was possible to have curved edges with sufficient smoothness.

A method of manufacturing a ceramic substrate according to the present invention is schematically shown in FIGS. 1a and 1b. A, A' in a of Figure 1,
One rectangular ceramic green sheet 1 of B, B', C, and C' is punched out or cut and prepared.

This green sheet 1 is bent to form a ceramic molded body 2 as shown in FIG. 1b.

That is, the green sheet 1 is moved from the central part C-C' to A
Fold in half so that A overlaps B and A′ overlaps B′.
Join. This creates a curved surface at one end 3.

The edge 3 of the curved surface of C-C' is originally the surface of the substrate, so it is smooth like the substrate surface, and the connection between the substrate surface and the curved edge 3 is as follows. It is a continuous curved surface. Therefore, even when this ceramic molded body is fired to produce a ceramic substrate, the properties remain the same and a ceramic substrate with highly smooth end faces 4 can be obtained.

The ceramic green sheet to be used is an inorganic oxide or a mixture thereof, or an inorganic powder raw material, which is a material for the ceramic substrate, such as alumina, silica, magnesia, talc, kaolin silica, carbon calcium, etc., or a filament material added to these to lower the melting point. A slurry or cup soil made of powder mixed with a vitrified substance is formed into a sheet shape by a doctor blade method or an extrusion method.

Its thickness is in the range 0.01mm to 3.0mm, preferably in the range 0.05 to 1.0mm;
It depends on the board design and the circuit design to be manufactured.

Materials used for the conductor layer include gold, silver,
It is a metal with good electrical conductivity, such as copper, platinum, molybdenum, or tungsten, and its paste can be printed on the surface of a ceramic substrate by screen printing or the like to form a conductive layer.

In the example, an alumina substrate was shown as an example, but other ceramic substrates such as SiC, AlN
Similarly, the ceramic substrate of the present invention can be applied and created to high thermal conductivity substrate materials such as PZT, piezoelectric substrates, BaO-TiO ₂ and other dielectric substrates, Ni-ferrite and other magnetic substrates, etc. can do.

Alumina, kaolin, talc, silica stone,
Examples include calcium carbonate, but these are clay minerals, and their compositions vary considerably depending on the mineral's production area, lot, etc., and when using it,
The minerals must be analyzed and the blended amount must be adjusted to match the target composition value. Furthermore, in addition to the above clay materials, pure chemical raw materials or glass raw materials of similar composition can also be used.

Techniques for forming ceramic green sheets are divided into non-aqueous and aqueous. The non-aqueous forming method is a method in which inorganic powder, which is the raw material for the ceramic substrate, is kneaded with an organic solvent and then molded. Water-based green sheet molding involves kneading and molding with water. The present invention can be applied to both nonaqueous and aqueous systems.

In the non-aqueous green sheet forming method, polyvinyl butyral, acrylic resin, nitrocellulose, polyethylene, polyvinyl chloride, etc. can be used as the binder, and dibutyl phthalate, dimethyl phthalate, dioctyl phthalate, etc. can be used as the plasticizer. Butyl stearate, etc. Dispersants include monoolein, fatty acids, fish oil, benzenesulfonic acid, etc. Solvents include methanol, ethanol, isopropanol, butanol, benzene, toluene, xylene, acetone, methyl ethyl ketone, Organic solvents such as trichlorethylene can be used.

Furthermore, in the aqueous green sheet forming method, acrylic resin, ethylene oxide polymer, ethyl cellulose, methyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, isocyanate, wax, etc. can be used as the binder. As the plasticizer, ethylene glycol, dibutyl phthalate, butylbenzyl phthalate, ethyl toluenesulfonate, etc. can be used. As the dispersant, polycarboxylic acid ammonium salt, phosphate glass, allyl sulfonate, etc. can be used.

The ceramic substrate obtained according to the present invention can be used, for example, as a thermal head substrate, an IC substrate, etc.

Next, the production of the ceramic substrate molded article of the present invention will be explained, but the present invention is not limited to the following examples, and may be used with other green sheet compositions.

Example 1 Ceramic raw material powder with a 96% alumina composition consisting of 300 g of alumina powder, 4 g of talc, and 15 g of clay was added with polyvinyl butyral as a binder.
30 g, 200 ml of trichlorethylene and ethanol combined as a solvent, and 15 ml of dibutyl phthalate as a plasticizer, and mixed in a 1.61 capacity ball mill for 24 hours. The resulting slurry was shaped using a doctor blade method, dried, and thickened. A 0.6 mm green sheet was obtained. This green sheet was bent, bonded by thermocompression bonding, and fired by the method shown in FIG. Although the cracking rate of the products taken out after firing was quite high, in the products obtained without cracking, the average surface roughness of the curved surface at the end was approximately 0.4 μm. It was hot. This has the same roughness as the surface of a fired ceramic substrate, and there are no surface defects such as protrusions, so in order to form a conductor layer on the end surface by a method such as screen printing, it is necessary to
Sufficient surface texture.

Example 2 A similar test was conducted using three times the amount of plasticizer as in Example 1. The obtained ceramic green sheet had higher flexibility. Using the green sheet with increased flexibility, baking it,
A ceramic substrate was obtained. As a result, it was possible to obtain a ceramic substrate having a curved edge portion with reduced cracking during thermocompression bonding and firing.

Example 3 The same lot of green sheets as in Example 1 were applied with an organic solvent to the parts to be bent and joined, and then bent, joined, and fired to obtain a ceramic substrate. As a result, an integrated ceramic substrate with smoother curved edges could be obtained.

Example 4 A ceramic substrate was manufactured in the same manner as in Example 3 by applying an adhesive prepared by dissolving a binder in an organic solvent instead of using the organic solvent in Example 3. As a result, we were able to obtain an integrated ceramic substrate with smoother curved edges.

In the present invention, the composition of raw materials for the ceramic substrate, such as alumina, must be changed depending on the use of the ceramic substrate to suit the purpose of the substrate. Furthermore, the blending ratio of the inorganic powder and the binder etc. varies greatly depending on the particle size distribution of the inorganic powder, the degree of polymerization of the binder, the viscosity, etc., and must be determined based on the castability and handling properties of the green sheet.

In addition, in the above example, the case was explained using the casting molding method using a doctor blade, but
In addition to this, it can be produced according to the present invention by any of extrusion molding methods, wet pressure molding methods, etc.
By processing the green sheet, a ceramic substrate having the novel shape of the present invention can be manufactured.

[Effects of the Invention] As described above, the present invention can provide a ceramic substrate whose end face can also be used as a surface on which an electric circuit can be mounted. Ceramic substrates can now be used to make use of end faces on which conductor layers could not be formed, increasing possibilities in the design of hybrid ICs and other electrical components and circuits, and increasing the degree of freedom in design. This also makes it possible to create compact electrical components that effectively utilize three-dimensionality.

Further, according to the present invention, it has become possible to manufacture ceramic substrates and integrated circuits with complicated structures through simple steps and at low cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of the ceramic substrate of the present invention and the method for manufacturing the molded body. [Description of symbols of main parts], 1... Ceramic green sheet; 2... Ceramic molded body; 3...
Curved edge.

Claims (1)

[Claims] 1. It is characterized in that it is produced by molding a ceramic green sheet, bending and joining the green sheets, and firing a green sheet molded body in which the bent portion forms a curved surface. Ceramic substrate with smooth curved edges. 2. A method for manufacturing a ceramic substrate having smooth curved edges, which comprises forming a ceramic green sheet, bending and joining the green sheets, and firing a green sheet molded body in which the bent portion forms a curved surface. .