JPH06252288A - Manufacture of ceramic multilayer substrate - Google Patents

Abstract

PURPOSE:To provide a method for-the manufacture of multilayer substrates which does not necessitate any precision metal molds in laminating and pressing ceramic green sheets. CONSTITUTION:Binder is applied to a green sheet, and an upper sheet is aligned and placed thereon. Compressed air is blown under a pressure within the elastic deformation range of the green sheets, to bond them together. The process above is repeated until a required number of green sheets are laminated and bonded. The edges of the resultant laminated body are cut to form it into a required shape, and it is then fired. Since green sheets are pressed under an air pressure within their elastic deformation region in the method, the laminated sheets will be not be deformed. The method allows multilayer sheets having recesses or notches to be laminated and bonded with precision, and causes no variation in shrinkage percentage due to plastic deformation after firing. This obtains multilayer substrates having a precise shape without need for precise metal molds for press.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic multilayer substrate, and more particularly to a method for producing a ceramic multilayer substrate by laminating and pressing ceramic green sheets.

[0002]

2. Description of the Related Art Conventionally, in the case of manufacturing a ceramic multilayer substrate, in a laminating / pressing process, sheets are sequentially laminated, and then a precursor laminated body of the ceramic multilayer substrate is prepared by a method of integrating them by applying temperature and pressure. After that, binder removal and firing were performed to manufacture a ceramic multilayer substrate. As a means for applying pressure, a method of uniaxially pressing with a pressure in a plastic deformation region by a metal mold is generally used.

Ceramic multi-layered substrates depend on their use.
Various shapes are required, such as having recesses for mounting ICs and notches. Conventionally, when pressing laminated green sheets, molds were made in accordance with the respective shapes, and the molds were replaced each time to manufacture a substrate having a shape according to the requirements.

[0004]

Since the dimensional accuracy required for a ceramic multilayer substrate is usually 100 μm or less, it takes a lot of time and labor to make a mold suitable for the required shape. Also, changing the mold requires time and effort. Therefore, there has been a demand for a lamination pressing method that can produce ceramic multilayer substrates of various shapes without using such a mold.

[0005]

Means for Solving the Problems As a result of repeated research on a laminating press method capable of producing ceramic multilayer substrates of various shapes without using the above-mentioned molds, the inventors have The inventors have found that the green sheets can be laminated and pressed without impairing the dimensional accuracy by pressing each green sheet with compressed air each time.

That is, according to the present invention, in a ceramic green sheet (hereinafter simply referred to as sheet) laminating / pressing step, a step of applying a binder to the sheet and a step of placing a sheet constituting an upper layer on the sheet in alignment with each other. And a step of sequentially bonding the sheets by blowing compressed air on the sheets with a pressure within the elastic deformation region of the sheets to sequentially laminate the sheets.

As the sheet used in the present invention, the ceramic green sheet which has been conventionally used can be used as it is. For example, a sheet formed of a powder of alumina, an alumina / glass system, aluminum nitride or the like and an organic binder is typical. Of course, in addition to this, the type is not limited as long as it is a sheet made of so-called ceramic powder and an organic binder.

The binder applied to this sheet is composed of components that are almost removed during firing, and the kind and components are not limited as long as the adhered sheets are not peeled off by firing. . A baking residue may be present as long as the properties of the substrate and the conductor are not deteriorated after baking.

Since this binder is compatible with the sheet, a simple test is appropriately performed depending on the sheet used.
It is preferable to use after confirming that conduction between the sheets after firing is not hindered, that the sheets are in close contact even after firing, and that no other inconvenient phenomenon occurs.

As a method for applying the binder, conventionally known methods such as screen printing, brush application, sponge roller application, spray application and the like are used. Particularly, the spray method is easy to control the application amount. The coating amount of the binder cannot be limited because the optimum amount varies depending on the binder and the sheet, but if it is too large, it is easy to peel between the sheets after firing,
If the amount is too small, peeling occurs before firing, so it is preferable to determine the optimum amount by experiments.

The binder may be applied to the surface on which the next sheet is to be laminated, or may be applied to the lamination surface of the sheet to be laminated.

In aligning the sheets constituting the upper layer, a conventionally known method, for example, a guide pin method can be used. That is, it is a method of using a stacking jig provided with a plurality of positioning pins and determining the position by a guide hole formed in a sheet or a frame carrying the sheet.
In addition, any means can be adopted if accurate alignment is possible.

As a concrete method of blowing the compressed air, there are a method of blowing the compressed air over the entire surface at once from the same opening as that of the sheet, and a method of moving the sheet evenly while blowing using a thin nozzle. However, depending on the binder used, it may be easy for air to be entrained between the sheets.In such a case, use a nozzle that has a slit-shaped opening with a length about the same as the sheet width, and use it from end to end. By moving it, the entrained air can be pushed out.

As the pressure of the compressed air to be blown, the pressure in the elastic deformation region (not plastically deformed) of the sheet is used. Since the pressure in the elastic deformation region differs depending on the type of sheet, it is necessary to confirm it by experiments. If a pressure exceeding this pressure range is applied to some part of the sheet, the sheet in that part will plastically deform, the positional accuracy of the sheet will be disturbed, and the shrinkage factor after firing will change, so the ceramic multilayer of the desired shape The substrate may not be obtained.

When the stacked sheets have a step such as a recess for mounting an IC, the pressure applied thereto decreases as the distance from the nozzle increases, but within the elastic deformation region, the pressure difference causes contraction after firing. Not affected by the rate.

[0016]

[Function] If the laminated sheet has a recess for mounting ICs, it is necessary to make a mold according to the shape of the recess, and the accuracy is usually within ± 10 μm, which is very strict. Otherwise, the pressure applied to the sheet during pressing will be distributed. In the conventional method, pressing is performed with the pressure in the plastic deformation region, so if there is a pressure distribution, the amount of plastic deformation of the sheet differs depending on the location, and there is a risk that the desired shape may not be obtained after firing.

In the present invention, since a high pressure is not required for the binder to bond the sheets and the pressure in the elastic deformation region can be used, even if the pressure can be distributed, it does not affect the shrinkage rate after firing. . Therefore, since it can be pressed by blowing air from the surface, a mold is not required according to the shape.

[0018]

Example 1 A slurry prepared by adding a water-based binder of polyacrylic emulsion to 50 parts of lead zinc borosilicate glass and 50 parts of alumina powder was coated with a doctor blade to obtain a thickness.
A 185 μm ceramic green sheet was made.

When compressed air was blown from the nozzle used in the following examples and the pressure at which this sheet started plastic deformation at room temperature was measured, it was the point when the original pressure of the nozzle exceeded 25 kg / cm 2. It was also found by experiments that, below this pressure, the sheets are not bonded even when laminated and pressed without a binder, but if the same binder as the sheets is applied thinly, it can be bonded with a pressure of 0.1 kg / cm2 or more.

This sheet was cut into 10 cm squares and 20
Two, three, and four sheets were punched out to punch square holes of 15 mm square, 15 mm square, and 10 mm square, respectively. We also prepared four 10 cm square sheets without square holes. further,
Guide holes of φ3.0 mm were punched in the upper right and lower left of each sheet. The center coordinates (mm) of the guide hole when the lower left corner of the seat is the vertex are (8, 8) and (92,
92)

A water-based binder of the above polyacrylic emulsion was diluted with water to prepare a binder coating solution having a solid content of about 15%, which was put in a spray gun for painting. On the other hand, the stacking jig was provided with guide pins matching the guide holes of the sheet.

One of the above-mentioned sheets having no square holes was set on a laminating jig through a guide pin, and the guide pin (both two) was masked to apply a binder solution to the surface by spraying. The amount was such that the surface of the sheet was clouded by dew. The reason why the guide pin is masked is that if the binder adheres to the guide pin, the sliding property with the guide hole deteriorates, and if the binder is applied to the entire surface, handling of the sheet becomes difficult.

A sheet having no square holes was placed on the sheet through the guide pins. At this point, much of the air had already adhered to the sheet below, but the air that had been trapped and lost the escape area remained as blister in some places.

A nozzle having an opening with a width of about 1 mm and a length of about 80 mm was floated from the sheet by about 1 mm, and was moved from end to end while blowing compressed air to the sheet. At this point, no blisters due to air left between the sheets were observed. The original pressure of the compressed air that was blown (the pressure before it was blown out from the nozzle) was approximately 5 kg / cm2.

In the same manner, the remaining sheets having no square holes were laminated and adhered, and then four sheets having a 10 mm square hole in the center were laminated and adhered in the same manner. Then, three sheets having 15 mm square holes and two sheets having 20 mm square holes were laminated and adhered in the same manner.

The 13-layer laminate (before firing) produced as described above had a thickness of 2.41 mm and the thickness of 13 sheets before pressing was maintained, and no deformation of the formed recesses was observed. It was

Binder-uncoated part 4 at the end of this laminate
Each side was cut off by 10 mm and baked at 850 ° C. for 10 minutes. In the obtained ceramic multilayer substrate, neither delamination between layers nor deformation of recesses was observed.

Example 2 A slurry having an aqueous solution of methyl cellulose added as a binder to alumina powder was applied by a doctor blade method to form a sheet having a thickness of 250 μm. When the pressure at which this sheet starts plastic deformation at room temperature (25 ° C.) was measured, it was 12 kg / cm 2.

Sheets were cut and punched in the same manner as in Example 1 and laminated in the same manner as in Example 1 except that compressed air having an original pressure of 9.8 kg / cm 2 was blown. The thickness of the obtained laminate was 3.25 mm, and the thickness of 13 sheets before pressing was maintained.

There was neither peeling between layers nor deformation of the recesses of the multilayer substrate obtained by firing this laminate at 1550 ° C. for 1 hour.

Comparative Example 1 The same operation as in Example 1 was carried out except that the compressed air pressure was 25 kg / cm 2. The thickness of the laminate (13 layers) before firing is 2.
At 35 mm, it can be seen that the sheet is plastically deformed in thickness by pressing compressed air.

In the multilayer substrate obtained by firing this laminate at 850 ° C. for 10 minutes, the concave portions were deformed.

Comparative Example 2 The same operation as in Example 2 was carried out except that compressed air was not blown. In this case, unevenness due to blisters was observed in places on the obtained laminate. When this was fired, the blistered part swelled further and caused a large deformation.

[0034]

As described above, in the manufacture of ceramic multilayer substrates, it has been very difficult to form a recess without deformation without using a precise mold, but according to the present invention, a special mold is used. It has become possible to form a ceramic multilayer laminate easily and quickly without the need for the above. That is, since it is not necessary to make or replace a precision mold, the delivery time of the ceramic multilayer substrate can be shortened and the cost can be reduced.

Claims (1)

[Claims] 1. A method for manufacturing a ceramic multilayer substrate by laminating and pressing ceramic green sheets, the step of applying a binder on the green sheets, and the step of placing the sheets constituting the upper layer in alignment therewith. And a step of spraying compressed air from above on the sheet with a pressure within the elastic deformation region of the sheet to perform adhesion between the sheets, and the green sheets are sequentially laminated to successively produce a ceramic multilayer substrate.