JPS6146096A - Method of producing ceramic board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to solve the following 1435 problems.

(Industrial Application Field) The present invention relates to a method for manufacturing a ceramic substrate.

(Prior Art) In a conventional method for manufacturing a ceramic substrate, a ceramic forming composition is mixed with a binder such as polyvinyl butyral, polyvinyl alcohol, or polyacrylic resin together with toluene, ethyl alcohol,
A method of manufacturing a ceramic substrate using a green sheet obtained by dispersing and mixing in an organic solvent such as Kijirole or ethanol to form a slurry (for example, the method disclosed in Japanese Patent Publication No. 59-22399) After forming the green sheet, the sheet itself may dry and shrink and become deformed, resulting in a poor yield, or when the sheets are laminated and bonded together, they must be heat-pressed at a temperature of 100 to 150°C for about 15 minutes. Adhesion between sheets cannot be achieved reliably,
The disadvantages are that the work takes a long time, and that the organic solvent evaporates, creating a poor working environment.

(Problems to be Solved by the Invention) This invention eliminates the above-mentioned conventional problems and provides a ceramic substrate that has a good sheet yield, facilitates mutual lamination and adhesion of sheets, and maintains a good working environment. The present invention aims to provide a method for manufacturing.

The configuration of the present invention is as follows.

(Means for Solving the Problems) The present invention takes the measures as described in the claims.

(Example) (1) First, aluminum oxide A1203 (20-60
fffffi%), boron oxide B20. (3 to 15 weight% weight silicon dioxide SiO□ (20 to 70 weight%), alkali metal oxides (1 to 5 weight% weight, group ■ element oxides (
A ceramic composition (powder) selected from a composition range of 0.01 to 0.5% by weight so that the total amount is 100% by weight is dry-pulverized and mixed using a ball mill for 24 hours.

(2) Add water (pure water) (15 to 40% by weight) to the pulverized ceramic powder (composition) and a dispersant (synthetic polycarboxylic acid salt: e.g. Aron A-6114 (manufactured by Toagosei Kagaku))
(0.1 to 10% by weight) within the respective ranges and kneaded in a ball mill for 2 to 3 hours.

(3) Next, an organic binder (acrylic water-soluble resin: e.g. Aron AS-1600 (manufactured by Toagosei Chemical Co., Ltd.)) (10 to 25% by weight) is added to the mixture being kneaded, and then 2
Knead for ~3 hours.

(4) Add an antifoaming agent (0.1 to 5 ounces by weight) to the kneaded mixture and knead again for 2 to 3 hours to form a slurry.

(5) This slurry is vacuum degassed (30 minutes to 1 hour) and then left to stand for about 10 to 20 hours.

(6) Next, the slurry is poured onto a film using the doctor blade method to form a green sheet (also called a green sheet) with a uniform thickness of approximately 200 μm to 600 μm, and then air dried (left indoors at 20°C for 10 to 20 hours). , and then heat-dried (40°C, 60°C).

80℃ for 30 minutes to 1 hour each)...Dry your fists with hot air.

(7) Next, cut the green sheet to the required size, for example 50m++
+ Punch out a rectangle of 60 mm (using a punch, punch, or die, for example), and punch through holes in the layers that require through holes.

(8) Pt, Au-Pt onto the punched green sheet
, Au-P d-P t, Ag-P d, Au
-Pd, Pd, Au, Ag-Au, Ag, Cu.

A conductive paste mainly composed of Ni, Cr, etc. is printed at predetermined positions by screen printing, and the conductive paste is also injected into the through holes. The printed green sheet is heated and dried. (For example, by far infrared rays at 120℃
(~20 minutes) (9) Laminate multiple sheets so that the dried green sheets form a predetermined circuit and the thickness of the substrate becomes the predetermined thickness, and pressurize and bond them together (pressure 1
0 to 60 K gl 2, pressurizing time 10 to 30 seconds), and then cut into a predetermined shape with a cutter. Note that the above-mentioned pressure adhesion must be performed while the sheet remains flexible, and is generally performed immediately after printing.

Please do this after leaving it in a humidity controlled room for a certain period of time.
Moisture may be applied by spraying or the like.

In the case of pressure bonding, the sheet always contains water because a binder with hydrophilic groups is used, so when pressure is applied to the polymeric sheet, the water contained in the sheet is released. The overlapping surfaces of the sheets become glue-like. As a result, the sheets become glue-like and adhere to each other as if they were originally one piece of material.

(10) The laminated green sheets are placed in an electric furnace and sintered in air (in an oxidizing atmosphere) at a temperature range of 800 to 1000°C (for example, 850°C) for 1 hour.

The firing pattern is, for example, 260~b~1000
The temperature is raised to .degree. C., then held at that temperature for 1 hour for sintering, and then cooled to room temperature over about 2 hours.

Note that the binder contained in the green sheet is removed when the temperature is increased during the firing process.

(11) As a result of the above firing, a multilayer ceramic substrate is completed.

Next, the ceramic composition, binder, etc. will be explained in more detail.

The ceramic composition is a so-called glass-ceramic, and in order to enable sintering at low temperatures, silicon dioxide (Sin2) is used for aluminum oxide (AI, O5).
The composition is designed to increase the ratio of alkali secondary metal (sodium oxide, N
a'20, potassium oxide 20, magnesium oxide Mg
Only a small amount of O1 oxidizing power (CaO1) is used.

In addition, in the composition of the ceramic, if (a) alumina (aluminum oxide Al2O,) is less than 20% by weight in terms of oxide, the bending strength will decrease and electrical properties such as insulation will deteriorate; If the temperature exceeds 1000°C, sintering cannot be performed.

(b) If silicon dioxide (Sin2) is less than 20% by weight, 1
It is difficult to sinter ceramics at temperatures below 70,000°C.
If it exceeds % by weight, the bending strength will decrease.

(c) If the amount of boron oxide (B2.0.) is less than 3ffi, sintering at 1000° C. or lower is difficult, and if it exceeds 15% by weight, the expansion coefficient during sintering becomes undesirable.

(d) 100 if the alkaline earth metal is less than 0.1% by weight
Sintering at 0°C is impossible, and if the content exceeds 5% by weight, electrical properties (insulation resistance, dielectric tangent) will deteriorate.

(e) Group ■ metals (iron oxide Fe206, nickel oxide Ni
01 Rutium oxide Ru01, Rhodium oxide Rh, O□
) is less than 0.01% by weight, physical properties such as resistance deteriorate, and when it exceeds 0.5% by weight, electrical properties such as insulation resistance deteriorate.

Only by using the above composition can we obtain a ceramic substrate that has satisfactory electrical and mechanical performance, is durable for practical use, has a low expansion coefficient (close to that of silicone), and can be sintered densely at a low temperature of 1000°C or less. be able to. Also, this allows Ag, Au-Pd, Pt, Cu as a conductor.
, Ni, etc., and alloys of these materials can be used, so the wiring can be further miniaturized and the packaging density can be increased.

In addition, since the sintering reaction of the conductor paste and the ceramic composition occurs simultaneously and shrinkage occurs in the vertical, horizontal, and thickness directions during sintering, it is possible to sinter in a free state, resulting in a dense ceramic substrate without voids or pinholes. . The conductive paste used in the above process consists of conductive metal fine powder, a solvent, and an organic binder to prevent the frit (glass powder) contained in the conductive paste from reacting with the ceramic layer and sinking into the boundary during sintering. It is difficult to use a so-called fritless type conductive paste consisting of (to prevent the resistance value of the conductor wiring from increasing and at the same time to enable soldering).

Next, the organic binder, water (pure water), and antifoaming agent will be explained.

A water-soluble acrylic resin is used as the organic binder. This water-soluble acrylic resin has the following molecular structure.

Hydrophobic group 1 Hydrophilic group If this binder is mixed with water into ceramic powder and kneaded, since there is a hydrophilic group, ammonium acrylate, this will combine with water and the binder will dissolve in water, resulting in a good slurry. I can do it.

Further, in the case of a green sheet made from the above slurry, ammonia (NH3) is released by heating in the above manufacturing process, for example, when the green sheet is heated and dried after forming the green sheet or after screen printing.

C0ORI C0OH 1 (acrylic acid) However, the sheet still contains the hydrophilic group acrylic acid (
COOH) remains, which combines with moisture in the air (indoors) to maintain the flexibility of the green sheet. In other words, if the green sheet is stored under constant humidity control, it can be used at any time even if it has been left unused for a long time.

In addition, if the green sheets containing the binder are left for a long time and become extremely dry, or if they become defective during the manufacturing process such as punching, cut these green sheets into small pieces, adjust the pH with ammonia water, When kneaded, it can be dissolved in water and can be used again as a slurry.

Next, the above binder has a thermal decomposition property that is almost 100% thermally decomposed when heated for 2 hours at a temperature increase rate of 5°C/min, that is, when the temperature reaches 600°C. The binder can be completely removed during the heating process (6° C./min, 3 hours) during firing of the laminated sheet.

Note that if the binder content is less than 10% by weight, cracks will occur during sintering, making it impossible to produce a good sheet.

On the other hand, if it exceeds 25% by weight, flexibility will be lost, handling will be poor, and pressure adhesion during lamination will be insufficient.

Next, if the amount of water (pure water) is less than 15 times, the slurry will have a high viscosity and cannot be sufficiently kneaded. Moreover, if it exceeds 40% by weight, it will take a long time to dry the green sheet.

Next, if the amount of the dispersant is less than 0.1% by weight, the viscosity (property) is too high and a large amount of water is required. Moreover, if the antifoaming agent exceeds 2% by weight, cracks tend to occur in the sheet.If the antifoaming agent is less than 0.1% by weight, bubbles will not disappear and pores (voids) will be generated in the ceramic sintered body. If it exceeds 1.0% by weight, the surface of the sheet will not be smooth.

(Effect of the invention) As described above, in this invention, it takes a long time from the time when a raw sheet is manufactured to the time when it goes through processes such as cutting and disposing conductors, and the time when it is laminated and pressure-bonded. Even if it takes a lot of time (for example, you can produce a large amount of raw sheets in advance, then cut them and prepare the circuit conductors, or do the work to prepare the circuit conductors the day before. (e.g. when laminating them the next day and bonding them under pressure, etc.)
This has the effect of maintaining the flexibility of the raw sheet in the 4A' state when stored at room temperature.

Furthermore, when laminating and pressurizing materials equipped with circuit conductors, only applying pressure at room temperature will prevent the overlapping surfaces of the sheets from forming a glue-like surface because the sheets contain a binder with hydrophilic groups. It has the advantage that the sheets can be bonded together. This has the effect of eliminating the drawbacks of conventional adhesives using organic binders and allowing the bonding work to be carried out quickly and safely.

Furthermore, if a defective product is produced when cutting a raw sheet, the defective product can be mixed with water and used again as a raw material, which has the effect of saving resources.

Claims (1)

[Claims] A ceramic forming composition such as alumina, a binder made of an acrylic water-soluble resin with a molecular structure having a hydrophobic group and a hydrophilic group, and water are mixed and then formed into a sheet to form a green sheet. After that, the raw sheet is cut into a desired shape and a circuit conductor is provided on the surface of the sheet, and then the sheets are laminated and pressed to adhere to each other, and the sheets are further fired. A method of manufacturing a ceramic substrate.