JPS61146753A - Manufacture of circuit substrate green sheet - 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] [Technical Field of the Invention] The present invention relates to a method for manufacturing a green sheet for a circuit board,
More specifically, the present invention relates to a method for producing a green sheet for a circuit board, in which a slurry can be easily formed into a sheet when a doctor blade method is applied during its production, and which can be easily peeled off from a molding support after molding.

[Technical background of the invention and its problems] In recent years, under the influence of the trend toward miniaturization of electronic equipment including office automation equipment, there has been an increasing demand for high-density multilayer wiring circuit boards. A multilayer wiring circuit board has a multilayer structure in which insulator layers and conductor pattern layers, which are wiring layers, are alternately laminated.

The material for such a circuit board should have well-balanced characteristics,
In other words, Al2O3 and Ba have high thermal conductivity, good electrical properties (electrical insulation), and high mechanical strength.
d, 5i02. Inorganic substances such as B2O3 and 5n02 are frequently used.

By the way, the manufacturing process of this circuit board is generally divided into two steps: manufacturing a molded sheet made of the above-mentioned inorganic material, the so-called green sheet, and sintering after alternately laminating a predetermined number of the obtained inorganic green sheets and conductor layers. It consists of the process of

The above-mentioned green sheet is generally manufactured as follows. That is, the above inorganic powder is mixed with an organic binder, a dispersant, a deflocculant, etc. to form a slurry, and then the slurry is molded onto a molding support, such as a polyester film, by a doctor blade method (hereinafter referred to as doctor molding). ) to form a sheet to a certain thickness, and after drying, this sheet is peeled off from the film to complete the green sheet. Incidentally, since this green sheet is then laminated, it is necessary to have sufficient mechanical strength in order to withstand the external force that is applied at that time. Due to such requirements, it is not appropriate to use a water-soluble binder as a binder during production, and it is preferable to use, for example, an organic binder.

However, when this organic binder is used.

In the above manufacturing process, a problem arises in that the sheet is not easily peeled off from the film after doctor molding. Since the releasability of this green sheet changes depending on the type of inorganic powder and organic binder used, it is extremely difficult to predict the degree of releasability at a stage before production.

Therefore, once it was discovered that the releasability was poor, the slurry components had to be significantly changed.

In addition, in particular, the inorganic powders include Ba and Sn.

When the main component is an oxide of B, acrylic ester is particularly suitable as the organic binder, but
When these are mixed to form a slurry, the viscosity of the slurry increases rapidly and gels, making it difficult to form into a sheet.

[Objective of the Invention] The present invention solves the conventional problems and provides a method for manufacturing green sheets for circuit boards by a doctor blade method using a slurry mainly composed of inorganic powder, in which the slurry can be easily formed into a sheet. The object of the present invention is to provide a manufacturing method that allows the sheet to be easily peeled off from the sheet support after molding.

[Summary of the Invention] The method for producing a green sheet for a circuit board of the present invention includes adding 0.01 to IQ, 0 parts by weight of an organic acid to 100 parts by weight of the inorganic powder to a slurry containing an inorganic powder as a main component. The method is characterized in that the mixture is formed into a sheet on a support by a doctor blade method, and then the sheet is peeled off from the support.

In the method of the present invention, the inorganic powder used as the raw material is
Although not particularly limited, A1203. Bad
, 5i02. B2O3,5n02. Cab, Z
nO.

One or a mixture of two or more oxides such as TiO2, MnO, ZrO, NgO, etc. may be used as appropriate.This inorganic powder may contain methyl ethyl ketone, n-butanol, acetone, ethyl acetate, etc., as necessary. ,benzene,
Organic solvents such as ethyl alcohol Niacrylic ester polymers or copolymers, methacrylic ester polymers or copolymers, polyvinyl butyral, vinyl acetate polymers and other organic binders: tributyl phosphate, dibutyl phthalate, diisodecyl phthalate, polyethylene glycol, etc. Plasticizers: Dispersants such as nonionic surfactants and anionic phosphate ester surfactants; Deflocculants such as oleic acid, ethyl oleate, and glycerin monooleate can be blended as appropriate. . These components desirably have a specific gravity comparable to that of the raw material powder in order to prevent slurry separation due to the difference in specific gravity and improve dispersibility when mixed with the raw material powder.

The organic acids to be added to the slurry mainly composed of the above-mentioned inorganic powder are not particularly limited, but include:
Any material may be used as long as it precipitates as a powder at the interface between the sheet and the molding support during the slurry molding/sheet forming step described below.Moreover, it is preferable that the melting point is 50°C or higher.Specifically, are oxalic acid, citric acid, tartaric acid, and malonic acid.

Myristic acid, adipic acid, L-ascorbic acid.

Examples include speric acid, sepacic acid, sorbic acid, and phthalic acid. Among these, oxalic acid, citric acid, tartaric acid, phthalic acid, and sebacic acid are preferred, and oxalic acid, citric acid, and tartaric acid are particularly preferred. The amount of these organic acids is 0.0 per 100 parts by weight of the inorganic powder! It is necessary to adjust the amount to 1000 parts by weight. The blending amount is 0.00 parts by weight per 100 parts by weight of inorganic powder.
If it is less than 0.01 parts by weight, it will not be possible to peel it off from a film such as a polyester film, while if it exceeds 10 parts by weight, cracks will occur in the obtained green sheet. Preferably it is 0.01 to 8.0 parts by weight, more preferably 0.01 to 8.0 parts by weight.
It is 5 to 6.0 parts by weight.

In addition, when using a powder that cannot be easily formed into a sheet, such as oxides of Ba, Sn, and H, as the inorganic powder, it is preferable to blend an organic acid containing a carboxyl group in particular. This prevents gelation of the slurry and facilitates forming it into a sheet. Needless to say, the sheet has good releasability in this case as well.

Hereinafter, one method of the present invention will be explained in detail.

First, the above-mentioned inorganic powder is pulverized and mixed by a conventional method to prepare a mixed powder serving as a raw material. This raw material powder has an average particle size of 0.8 to 2.04 m, more preferably 1.0 m.
” It is preferable that it is about 1.8 JLm. Then, the other ingredients mentioned above, such as an organic solvent, an organic binder, a dispersant, and a peptizer, are mixed with this raw material powder to form a slurry. A predetermined amount of organic acid is further added and mixed to the slurry. During this mixing, in order to uniformly disperse the raw material powder, it is preferable to adjust the overall viscosity to about 1 to 20 poise, more preferably about 5 to 10 poise. .

In addition, in the above mixing step, in the case of powders that easily gel immediately after mixing with the organic binder, such as oxides of Ba, Sn, and H, the raw material powder and other components except the binder are thoroughly mixed in advance, and then the binder and It is advisable to add an organic acid and mix again.

Next, the slurry obtained above is formed into a sheet on a polyester film or the like.

Prior to this step, in order to defoam the slurry, flatten the surface of the final green sheet, and provide sufficient mechanical strength, the slurry viscosity is adjusted to about 150 to 300 poise, more preferably 180 to 250 poise. It is desirable to adjust it to about poise.

Molding and forming into a sheet is carried out by the usual doctor blade method, and the thickness of the sheet can be set as appropriate.

After that, the sheet on the film is dried.

Suitable drying methods include infrared heating and air drying. At this time, the organic acid, which is a component of the sheet, precipitates in the form of powder at the interface between the sheet and the polyester film as described above, impairing the adhesion between the sheet and the film, thereby improving the releasability of the sheet. Finally, the sheet is peeled off from the film to complete a circuit board green sheet.

Examples of the above-mentioned oxides containing Ba, Sn, and B as main components include Ba, Sn, and B, such as Bad, 5n02
And in terms of B2O3, Ba0 1G ~418 +so1%5n02
, 9~50 mo1%8203 1
3~? An example is an oxide sintered body containing 2 mo1%. In such a sintered body, when BaO is large, it becomes brittle, when a2o3 is small, the sintering temperature tends to be high, and when 5n02 is large, the insulation resistance tends to be low.

In particular, such a composition exhibits excellent water resistance when BaSn(BO3)2 is at least 90 o1%, more preferably at least 95 o1%. It is particularly useful in application.

Oxides with such a composition (Ba5n(803) 290 mo 1% or more) are fired at a firing temperature of 1200°C or lower, especially at 90°C.
Low temperature firing of 0 to 1000°C is possible. In addition, this substrate has a small coefficient of thermal expansion α of about 3.5 to 8 (X 104 /l).
0), and is suitable for a hybrid board on which an LSI chip is directly mounted. In addition, other characteristics such as dielectric constant (about S13.5 to 10.5, galvanic loss tanδ
2-5 (X 10-3 ).

It has insulation resistance ρ10Ω・cl) and sufficient characteristics as a circuit board. Also, the resistance strength is 1000kg/c+*2
It has sufficient strength.

Furthermore, it has a low water absorption rate of 0.01% or less, and has excellent water resistance. Also, as an additive, AJ1203゜5i0
2. TiO2 can also be added as appropriate.

[Examples of Q Ming] Examples 1 to I3 and Comparative Examples 1 to 3 Inorganic powder A1203. Bad, 5i02.
8203, and mixed and pulverized them in a wet vibration mill at a predetermined mixing ratio to prepare a raw material powder with an average particle size of 1.2 endomere.Next, the following ingredients were added to 100 parts by weight of this raw material powder. were blended and mixed to form a slurry.

Methyl ethyl ketone (solvent) 23 parts by weight n-butanol (solvent) 10 parts by weight tributyl phosphate (
Plasticizer) 0.5 parts by weight Nonionic surfactant (dispersant)
0.1 part by weight acrylic acid ester polymer 15
The viscosity of the slurry was about 5 poise when mixed with parts by weight and 1 part of organic acid. This slurry was then degassed, the viscosity was adjusted again to about 200 poise, and then coated onto a polyester film to a thickness of about 400 l using a regular Dr.Frede machine.
Then, the sheet on the polyester film was heated at about 130° C. by an infrared heating device for about 1.
After drying for 0 hours, the sheet was peeled off from the film. The peelability of the green sheet at this time is shown in the table. Regarding the peelability results in Table 1, if the green sheet is completely peeled off from the film and the obtained sheet has no defects, it is considered "good", and if only a part of the sheet is peeled off or there is no peeling at all, it is considered "good". If not, it was described as "defective".

Example! 4 Inorganic powder “C” BaCO3, 5n02, B
2O3e was used, and these were mixed in a ring vibration mill and pre-calcined at 900N and 1050°C.Then, they were mixed and ground again in a vibration mill to prepare a raw material powder with an average particle diameter of 1.7%. Predetermined amounts of the same solvent and dispersant as used in Examples 1 to 6 above were blended with 100 parts by weight of this raw material powder, and these were placed in a pot and mixed for 24 hours. Thereafter, 18 parts by weight of an acrylic resin as a binder and 2.0 parts by weight of oxalic acid as an organic acid were added, and the mixture was further mixed for 24 hours. The viscosity of the slurry at this time was about 2 poise. After defoaming the slurry, the viscosity was adjusted again to 20 G poise. and,
The slurry was formed into a sheet using a doctor blade device as in Examples 1 to 13 above to obtain a sheet of 350 gm. In this process of forming and forming into a sheet, the slurry maintained an appropriate viscosity from beginning to end, and gelation of the slurry did not occur at all.

For comparison, when a slurry was prepared in Example 7 without adding any oxalic acid, the slurry gelatinized 5 minutes after mixing with the acrylic resin, making it impossible to form it into a sheet. Furthermore, the amount of oxalic acid added was 0.01
When the amount was less than 1 part by weight, the slurry gelled 2 hours after it was prepared. On the other hand, when more than 10.0 parts by weight of oxalic acid was blended, it was possible to form a sheet, but the sheet obtained had many cracks and was not suitable for practical use. Among organic acids, oxalic acid, acetic acid, citric acid, tartaric acid, etc. having carboxyl groups were easy to form into a slurry and sheet, and had very good releasability.

〔Effect of the invention〕

As is clear from the above description, if the method for manufacturing a green sheet for circuit boards of the present invention is applied.

Regardless of the type and composition of the raw material powder, it is easy to form a sheet during doctor molding, and furthermore, the sheet can be easily peeled off from the molding support, so the manufacturing process is very simple, and Yield is good. Therefore, its industrial value is extremely large.

Claims (1)

[Claims] 1. Add and mix 0.01 to 10.0 parts by weight of an organic acid per 100 parts by weight of the inorganic powder to a slurry containing inorganic powder as a main component, and mix the mixture with a doctor blade. A green for circuit boards, characterized in that the organic acid is precipitated as a powder at the interface between the sheet and the support by forming it into a sheet on a support by a method, and then the sheet is peeled off from the support. Method of manufacturing sheets. 2. The method for producing a green sheet for a circuit board according to claim 1, wherein the organic acid has a melting point of 50° C. or higher. 3. The green sheet for circuit boards according to claim 1, wherein the inorganic powder is a powder containing barium, tin and boron oxides as main components, and the organic acid is an organic acid containing a carboxyl group. Production method.