JPS63215580A - Ceramic metallization and metallizing adhesive sheet therefor - 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 Field of the Invention The present invention relates to a method for metallizing ceramics and a metal powder sheet for metallizing a ceramic sintered body-L.

”Irojutsu and its problems Metallization of ceramics has been well done for a long time.1
For example, one technique is to form electrodes on a ceramic sintered body such as a piezoelectric element, and the mainstream method is to screen print the ceramic sintered body 1 using a conductive paste containing metal powder and then bake it. Ta. However, the following points have been pointed out as problems with this method.

(1) Production efficiency is poor because the drying time of the conductive paste is long.

(2) Screen printing on a sintered body having an irregular cross section such as a curved surface or unevenness is difficult.

(3) The conductive paste used is required to have good screen printing properties, but it is not easy to adjust, and there are restrictions on the type and composition of materials.

In addition to the screen printing method, various methods such as spray coating, dipping, and brush coating have been proposed, but these methods have the drawbacks of uneven coating thickness, poor yield, and low productivity.

Problems to be Solved by the Invention The problems to be solved by the present invention are to avoid each of the problems of the prior art described above. More specifically, we will describe a metallizing method that allows metallizing on ceramic sintered bodies to be carried out easily and with high yield, and that can also be automated, as well as a metallizing sheet used in this method. The purpose is to provide.

Means for Solving the Problems In order to achieve the above objectives, this invention was developed by using a resin layer that has pressure-sensitive adhesive properties at room temperature on one side of a green sheet mainly composed of metal powder and an organic binder. By using this adhesive property to pressure-bond the ceramic sintered body, then firing and metallizing,
The present invention was completed based on the knowledge that all of the various problems encountered in the conventional metallization methods described above can be avoided.

That is, the present invention relates to an adhesive sheet for metallizing, in which a pressure-sensitive adhesive layer is provided on one side of a metal powder sheet containing metal powder and an organic binder as main components, and a metallizing method using this sheet.

Function and Structure of the Invention As described above, in the present invention, in order to pressure-bond a metal powder sheet containing metal powder and an organic binder as main components to a ceramic sintered body using a pressure-sensitive adhesive, conventional printing is not required. There is no need to employ methods such as a spray method or a spray method, and therefore, all the various problems caused by these methods can be avoided. However, since there is no need to dry the conductive paste, production efficiency is high, and metallization of sintered bodies having curved surfaces or irregularities is also easy.

Further, it is not necessary to take screen printability into consideration, and there is a large degree of freedom in selecting the type and composition of materials. Furthermore, since it uses a pressure-sensitive adhesive layer, it can be bonded with weak force and can be applied to fragile sintered bodies.

Moreover, if the pressure-sensitive adhesive layer has a thermal decomposition temperature higher than that of the resin binder constituting the metal powder sheet, in the firing process,
The resin binder that makes up the metal powder sheet is 214
Even if the metal powder is lost, the adhesion is good so that the metal powder does not peel off.

In the present invention, the metal powder is Ag, Ag-Pd
, A! ] −Pt , A(+ −Pd −Pt 1Au
.

Known metal powders such as Δu-pt, AI, Ni, Cu, and Pt can be used.

On the other hand, as resin binders, synthetic polymers such as hydrocarbon resins, vinyl resins, acetal resins, acrylic resins, styrene resins, polyester resins, polyurethane resins, and semi-synthetic polymers such as cellulose resins are used. However, since it is easy to thermally decompose, hydrocarbon resins,
Acrylic resins, acetal resins, and cellulose resins are preferred, and acrylic resins are particularly preferred. The blending amount varies depending on the specific gravity and particle size of the metal powder, but it is preferably in the range of 1 to 30 parts by weight per 100 suspended parts of the metal powder. If the amount is too low, the strength of the metal powder sheet will be reduced, resulting in significantly poor workability.

Further, in the present invention, 0.5 to 5 Qvo 1% of glass frit may be added to improve the adhesiveness between the ceramic sintered body and the metal powder.

As the glass frit, known ones such as sodium borosilicate and chlorine borosilicate can be used. Furthermore, in producing the metal powder sheet, a dispersant may be added to facilitate dispersion of the metal powder and to obtain a sheet with good surface smoothness and high density. Usual surfactants are used as dispersants,
Fatty acids, fatty acid esters, fish oils, acrylic oligomers, and the like can be used as necessary. The amount of dispersant used in this case is 0.01 to 1 part by weight per 100 parts by weight of metal powder.
0 part by weight, preferably about 0.1 to 2f11 parts.

A metal powder sheet can be produced by adding additives such as a suitable solvent and antifoaming agent to the above composition and using a conventional method such as a doctor blade method. That is, a metal powder sheet is produced by mixing metal powder, a resin binder, a solvent, and optionally additives such as a dispersant and an antifoaming agent using a dispersing machine such as a ball mill or three rolls, and casting with a doctor blade. Obtainable. The thickness of the metal powder sheet is usually 5 to 250 μm, preferably 10 to 250 μm.
It is about 150μ.

In the present invention, a pressure-sensitive adhesive layer is provided on the metal powder sheet, but in order to obtain good adhesion after firing, the metal powder sheet and the ceramic sintered body must be in sufficient contact with each other during lamination. Needless to say, it is important that the powder sheet does not peel off before the resin binder in the powder sheet disappears during firing. Therefore, the thermal decomposition temperature of the pressure sensitive adhesive layer is preferably set higher than the thermal decomposition temperature of the resin binder constituting the metal powder sheet. If a pressure-sensitive adhesive layer is not used, or if the thermal decomposition temperature of the pressure-sensitive adhesive layer is lower than that of the resin binder, the metal powder may peel off from the ceramic sintered body, such as curling up, or form edges. Some parts may shrink. Therefore, acrylic pressure-sensitive adhesives mainly composed of (meth)acrylic esters such as butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate, or rubber-based adhesives mainly composed of butyl rubber, etc. are preferably used. It is best to use pressure-sensitive adhesives. Means for increasing the thermal decomposition humidity of these pressure-sensitive adhesives include a method of copolymerizing polar monomers such as acrylic acid, methacrylic acid, and acrylamide with the above-mentioned (meth)acrylic acid ester, and a method of copolymerizing phenolic resins, etc. Examples include a method of blending resins that are poorly degradable. To provide a pressure-sensitive adhesive layer on a metal powder sheet, a pressure-sensitive adhesive solution is applied onto a release liner such as release-treated paper or polyethylene terephthalate film using a roll coater, and then dried. Although the method of transferring is generally used, the method is not necessarily limited to this method, and for example, spraying may be used.

If the thickness of the pressure-sensitive adhesive layer is too small, the adhesive force will be low, and if it is too thick, the amount of pyrolysis gas generated will increase, making it impossible to obtain sufficient adhesion. Therefore 1 to 10
It is preferably in the range of 0 μm.

The adhesive sheet produced by the above method can be easily pressed onto the ceramic sintered body because of the presence of the pressure-sensitive adhesive layer. For example, use a roller or the like to prevent air bubbles from entering.

Moreover, even better adhesion can be obtained by applying heat and pressure using a hot roll, hot press, or the like.

As the ceramic sintered body, known ones such as alumina, beryllia, steatite, forsterite, zirconia, barium titanate, lead zirconate titanate, etc. can be used.

When the metal powder layer-forming ceramic sintered body obtained by the method of the present invention is fired at a high temperature, organic substances such as the resin binder and pressure-sensitive adhesive are thermally decomposed and disappear, and the metal powder and ceramic sintered body are separated. The bonding strength is high, and there is no peeling of metal powder, wire breakage, misalignment, etc., and high quality metallizing can be performed.

The heating moisture level in the above firing process is determined as appropriate depending on the quality of the metal powder and glass frit used, but it is usually set appropriately in the range of about 500 to 1000°C depending on the type of each powder. Bye. The atmosphere during firing may be an oxidizing gas atmosphere or a non-oxidizing gas atmosphere depending on the type of each metal powder. For example, AQ
When powder or Pt powder is used, an oxidizing gas atmosphere can be used, and when Cu powder is used, a non-oxidizing gas atmosphere can be created by using nitrogen gas or the like.

The metallized ceramic sintered body obtained by the method of the present invention can be used, for example, as an electrode layer-forming ceramic sintered body, and can also be used in various other fields.

Effects of the Invention As described above, by using the adhesive sheet for metallizing according to the present invention, when metalizing a ceramic sintered body, since the sheet is formed in advance, the drying time is reduced, unlike when using conductive paste. Since there is no need for this, production efficiency is high, and there is no need to consider the rigidity of the screen marking, so there is a high degree of freedom in material selection. Further, since a pressure-sensitive adhesive layer is provided, good adhesion can be easily obtained even with a weak force, and it is also easy to attach to the surface of a ceramic sintered body having an irregular cross section such as a curved surface or unevenness. Furthermore, the thermal decomposition temperature of the pressure-sensitive adhesive layer is determined by the heat content w1 of the resin binder used in the metal powder sheet. If it is set higher than the temperature, the following advantages will be exhibited. That is, first, at the temperature at which the pressure-sensitive adhesive layer begins to thermally decompose, most of the resin binder in the metal powder sheet has already disappeared, and the metal powder sheet has air permeability. Therefore, the decomposed gas generated by thermal decomposition of the pressure-sensitive adhesive layer can easily pass through the metal powder layer, so that the metal powder sheet does not blister during the firing process.
Metal powder peeling, defects, etc. will no longer occur. Secondly, the metal powder sheet is powdered at the temperature at which the pressure-sensitive adhesive layer decomposes and loses its adhesive strength. It is possible to prevent the powder sheet layer from rolling up, shrinking, etc. and becoming misaligned. In this way, all the various problems that were unavoidable in conventional printing methods, spray methods, etc. can be solved, and high-quality electrodes can be formed without peeling, misalignment, etc.

EXAMPLES Below, examples of the present invention will be described in more detail.

Example 1 170 g of silver powder with an average particle diameter of 1.2 μm, 30 g of sodium borosilicate glass powder with a softening temperature of 625°C, and 35 g of polybutyl methacrylate (thermal decomposition end temperature of 350°C)
), 8 g of dibutyl phthalate, 16 (M) of toluene, and 25 (L) of ethanol were mixed in a ball mill,
It was shaped using a doctor blade to a dry thickness of 50 μm and dried to obtain a metal powder sheet. Next, the thickness is 20
An acrylic pressure-sensitive adhesive (thermal decomposition end temperature: 560° C.) containing μm polybutyl acrylate as a main component was laminated onto the metal powder sheet to obtain an electrode-forming adhesive sheet.

Lead zirconate titanate (hereinafter referred to as PZT) was used as a ceramic sintered body, and the above-mentioned adhesive sheet for electrode formation was pressed and fired. Firing was performed in the air, and the binder was removed at 400°C for 60 minutes, at 10°C/l1lin.
The temperature was raised to 700°C, held for 40 minutes, and then cooled in the furnace.

The formed electrodes were in good condition with no displacement or peeling.

Example 2 Silver-palladium alloy powder 450 with an average particle size of 0.2 μm
g, lead borosilicate glass powder with a softening temperature of 430°C 50
g, polybutyl methacrylate 35g (thermal decomposition end temperature 350°C) dioctyl phthalate 8g, sorbitan stearate 1g 1 toluene 110g, methyl ethyl ketone 7
A composition consisting of 5 g was mixed in a ball mill, molded using a doctor blade method to a dry thickness of 20 μm, and dried to obtain a metal powder sheet. Next, an acrylic pressure-sensitive adhesive having a thickness of 10 μm and mainly composed of butyl polyacrylate (thermal decomposition end temperature: 410° C.) was laminated onto the metal powder sheet to obtain an electrode-forming adhesive sheet.

An alumina substrate with a purity of 96% was used as the ceramic sintered body, and the above-mentioned adhesive sheet for electrode formation was pressed and fired. Firing was carried out in the air, and after removing the binder at 350°C for 60 minutes, the temperature was raised to 520°C at a rate of 10°C/mtn, and 40
After holding for a minute, the mixture was cooled in the oven. The formed electrodes were in good condition with no displacement or peeling.

(that's all)

Claims (3)

[Claims] (1) A method for metallizing ceramics, which comprises pressing an adhesive sheet, which has a pressure-sensitive adhesive layer on one side of a green sheet containing metal powder and an organic binder as main components, onto a ceramic, and then firing it. (2) An adhesive sheet for metallization, which has a pressure-sensitive adhesive layer provided on at least one side of a green sheet containing metal powder and an organic binder as main components. (3) The adhesive sheet for metallization according to claim 2, wherein the pressure-sensitive adhesive layer is thermally decomposed at a higher temperature than the organic binder.