JPH0521931A - Manufacture of glass ceramic substrate - Google Patents

Abstract

PURPOSE:To enable an electrode with an improved solder wetting property by applying an alumina substrate conductor paste in the market to a glass ceramic substrate by calcining a green sheet, an alumina paste, and a conductor paste collectively. CONSTITUTION:First, an alumina paste is printed and then dried for forming an alumina film in a same pattern as an electrode on a green sheet which consists of a glass powder and a ceramic powder. This alumina layer needs to be as thick as 3-15mum When the thickness is equal to 3mum or less, solder wetting property of the electrode is not sufficient. Also, when it is equal to or more than 15mum, strength of the alumina film is not sufficient and a problem of adhesion property of the electrode is generated. Then, a conductor paste is printed on this alumina film and then is dried. Various kinds of film-thickness conductive pastes which are available in the market can be utilized as the conductive paste. Finally, the conductive film, the alumina film, and the green sheet are as they are and are piled up on a desired another layer as needed and then they are baked at 800-930 deg.C.

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 glass ceramic substrate, and more particularly to a method for forming an electrode having excellent solder wettability by using a commercially available thick film paste for alumina substrate.

[0002]

2. Description of the Related Art In recent years, a glass ceramic substrate has been developed as a ceramic multilayer substrate for low temperature firing. This substrate is made into a slurry by adding an organic binder and a solvent to a mixture of amorphous glass or crystallized glass powder and ceramic powder such as alumina, and is formed into an insulating layer by molding into a green sheet by the doctor blade method. A paste-like composition in which powders of silver, copper, etc. are dispersed in an organic vehicle is applied onto the insulating layer by a technique such as screen printing to form an inner layer wiring pattern, and desired layers are laminated to form 800 to 9 layers.
It is obtained by firing at 30 ° C. Also, in the case of outer layer wiring,
As in the case of the inner layer wiring, there are adopted a method of printing on a green sheet and firing it collectively, and a method of printing a conductor paste after firing the green sheet and firing it separately.

[0003]

The inner layer wiring does not require solder wettability, while the outer layer wiring has solder solder wettability which is an important quality for connecting components with solder. When a commercially available conductor paste is applied to the wiring, there is a problem that almost no solder is attached.
This is because the glass component contained in the conductor paste does not move toward the glass ceramic substrate during firing and remains on the surface of the conductor film, and the glass of the glass ceramic substrate moves into the conductor film during firing and becomes a conductor film. Due to becoming glass rich.

An object of the present invention is to provide a method of applying a commercially available conductor paste for alumina substrate to a glass ceramic substrate and forming an electrode having good solder wettability.

[0005]

In order to achieve the above object, the method of the present invention is such that an alumina paste is printed in the same pattern as an electrode on a green sheet composed of glass powder and ceramic powder, and then dried to obtain a thickness of 3 to 15 μm. The step of forming an alumina film, the step of printing a conductor paste on the alumina film with an electrode pattern and drying, the conductor film, the alumina film and the green sheet as they are, if necessary, overlaid on another desired layer and collectively. And a step of firing at 800 to 930 ° C.

[0006]

In the present invention, various commercially available thick film conductive pastes, that is, silver pastes, silver-palladium pastes, and silver-platinum pastes can be used as the conductor pastes.

On the other hand, the alumina paste is a paste composition obtained by kneading alumina powder and an organic vehicle, and this composition is applied on a green sheet or a fired substrate by a screen of 150 to 400 mesh. Therefore, the powder to be used may have a particle size that can smoothly pass through this screen, and an average particle size of 2 microns or less with few particles of 10 microns or more is suitable. As a vehicle, a solvent prepared by dissolving ethyl cellulose, a methacrylate resin or the like in a solvent such as terpineol, butyl carbitol or toluene can be used. In order to make the paste suitable for screen printing, the vehicle may be 10 to 30 parts by weight based on 100 parts by weight of the solid content.

In the present invention, the glass-ceramic substrate may be one that can be sufficiently sintered at 930 ° C. or lower, and contains, for example, borosilicate glass as a base, lead oxide, zinc oxide, an oxide of an alkaline earth metal, and the like. Softening point 600-800
A raw material may be a mixture of amorphous glass powder at ℃ and a ceramic filler such as alumina, or crystallized glass that is crystallized at 600 to 900 ℃, and processed into a substrate in the next step. That is, the above powder raw materials are mixed with an organic binder, a plasticizer, and a solvent in a ball mill,
After defoaming the obtained slurry, it is formed into a green sheet by a doctor blade method, the green sheet is cut into an appropriate size, and an alumina paste is formed in the same layer as the electrode on the uppermost layer. It is printed and dried, and then a conductor paste is printed on the alumina layer with an electrode pattern and dried.

The thickness of the alumina layer must be 3 to 15 μm. This is because when the thickness is 3 μm or less, the solder wettability of the electrode is insufficient, and when it is 15 μm or more, the strength of the alumina film is insufficient and a problem occurs in the adhesion of the electrode. The above green sheet may be fired as it is, but in the case of manufacturing a multilayer substrate, the green sheets on which the inner layer conductors are formed are stacked, and the above green sheet is further stacked on the uppermost portion to obtain a pressure of 50 to 300 kg / cm ² , and a temperature. 60-90
It is advisable to integrate them by using a hot press machine under the condition of ° C.
The glass-ceramic multilayer substrate is obtained by pre-baking the thus obtained laminate at 350 to 600 ° C. to remove organic substances and then baking at 800 to 930 ° C.

According to the method of the present invention, since the glass component in the conductor paste has a strong affinity with alumina, it migrates to the alumina layer, and the glass in the glass ceramic is also fixed by the alumina layer and does not migrate to the conductor layer. The solder wettability is improved. Further, since the alumina layer is reinforced by the transferred glass, sufficient strength can be maintained.

In the above description, the glass ceramic green sheet, the alumina paste, and the conductor paste are collectively fired, but the glass ceramic green sheet may be fired first, and then the alumina printing step and subsequent steps may be similarly performed. The effect is obtained.

[0012]

EXAMPLE Alumina powder 100 having an average particle size of 0.54 μm
A part by weight was kneaded with 25 parts by weight of an organic vehicle to prepare a paste composition. A terpineol solution having an ethyl cellulose concentration of 22% by weight was used as a vehicle.

On the other hand, as a glass ceramic substrate, Pb
O3.07, SiO ₂ 51.7, Al ₂ O ₃ 8.4, B
₂ O ₃ 7.3 and CaO 1.9 glass powder (average particle size 2.2 μm) and alumina powder (average particle size 0.54 μm) each having a composition of 50% by weight were mixed at a ratio of 50/50, and the powder 100 9 parts by weight of polyvinyl butyral, 7 parts by weight of diisobutyl phthalate, 1 part by weight of oleic acid, 40 parts by weight of isopropyl alcohol, and 20 parts by weight of trichloroethane were added to parts by weight, and mixed by a ball mill for 24 hours to form a slurry. A 0.7 mm thick green sheet was formed by the blade method.

A small piece of 1 inch square is cut out from the green sheet, and an alumina paste is first screen-printed on the small piece with various electrode patterns by 0 to 18.9 μm.
Then, a commercially available silver-palladium paste (C-4160, C-4910 manufactured by Sumitomo Metal Mining Co., Ltd.) was printed on the alumina film and dried. The green sheet pieces were then pre-baked at 520 ° C. for 3 hours to remove organic substances, and subsequently baked at 900 ° C. for 1 hour, and the electrode films were subjected to the following tests.

(A) Solder wettability: Flux (Tamura Kaken Co., Ltd., XA-100) was applied on a 10 mm square electrode pattern, and the pattern was applied to a 37Pb / 63Sn solder bath (2
After being immersed in (30 ° C.) for 5 seconds and cooled, the wetted area ratio on the pattern was obtained. The results are shown in Table 1.

(B) Adhesive strength-2. A 0.65 mmφ plated copper wire is soldered on a 2 mm square pattern using 37 Pb / 63 Sn solder and pulled vertically to be peeled off.
The tensile force at the time of peeling was determined.

(C) Aging strength-The substrate to which the tin-plated copper wire was soldered in the same manner as above was left in a constant temperature bath at 150 ° C for 1000 hours and then subjected to the same peeling test as above.

[0018]

[Table 1]

In Table 1, the solder wetting of 80% or more, the adhesive strength of 4.0 kg or more, and the aging strength of 2.0 kg or more are indicated by a pass mark ◯ and a mark X below that mark.

The results shown in Table 1 are the results of Experiment No. Although all of the above three characteristics were passed in Nos. 1 to 7, Experiment No. From 8 to 13, it is shown that any of the characteristics fails if the alumina film is too thin or too thick.

[0021]

According to the method of the present invention, it is possible to form an electrode having good solder wettability and excellent adhesive strength on a glass ceramic substrate by using a commercially available conductor paste.

Claims (1)

Claim: What is claimed is: 1. A step of forming an alumina film having a thickness of 3 to 15 .mu.m by printing an alumina paste in the same pattern as an electrode on a green sheet made of glass powder and ceramic powder and then drying the alumina film. A step of printing a conductor paste on the electrode pattern and drying it, a step of directly laminating the conductor film, the marmina film and the green sheet on another layer as desired, and baking them collectively at 800 to 930 ° C. A method for manufacturing a glass-ceramic substrate having a.