JPH02270396A - Manufacture of multilayered ceramic board with built-in capacitor - Google Patents

Abstract

PURPOSE:To prevent recesses and voids from occurring in a board by a method wherein insulator paste is applied as thick as a dielectric paste to the part of a ceramic green sheet face where the dielectric paste is not applied, and the ceramic green sheets are bonded together by pressure and burned. CONSTITUTION:A capacitor electrode electrode 4 is formed on a green sheet 1 through a screen printing so thick as to be 10mum in thickness after drying, and a dielectric paste is printed thereon through a screen printing so thick as to be 40mum in thickness after drying. On the other hand, a green sheet 1' provided with opposed electrodes and a wiring conductor is manufactured, which is laminated on the above green sheet 1 and bonded together by thermo- compression, and a binder is removed from the bonded body, then the bonded body is burned at a temperature of 850 deg.C for 10 minutes into an integral structure for the manufacture of a multilayered ceramic board of this design. By this setup, the layers of a manufactured multilayered board are free of irregularities, and the multilayered board is enhanced in circuit component mountable area and improved in mounting density.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing a multilayer ceramic substrate with a built-in capacitor, and in particular to a method of coating a dielectric paste on a ceramic green sheet, and applying ceramic green of the same composition on the top surface. The present invention relates to an improvement in a method for manufacturing a multilayer ceramic substrate with a built-in capacitor, in which sheets are crimped and fired.

[Conventional technology] Conventionally, the method of manufacturing a ceramic circuit board with a built-in capacitor by co-firing involves printing electrodes on a ceramic green sheet, printing a dielectric paste on the capacitor formation area, and placing a counter electrode on top of that. There is a method of printing, repeating dielectric printing and electrode printing as necessary, and then stacking another ceramic green sheet and press-bonding it, and firing it together to produce a ceramic substrate with a built-in capacitor.

[Problem to be solved by the invention] However, in the case of this method, as shown in FIG.
In the laminated and integrally fired circuit board 10, a recess 13 is formed on the surface of the circuit board 10 located between the dielectric 11 and the adjacent dielectric 12, and as shown in FIG.
There is a drawback that a void 14 is generated between the dielectric material 12 and the adjacent dielectric material 12.

[Means for Solving Problem E] The present inventors applied an insulating paste made of the same material as the substrate material around the part where dielectric was printed or the part where dielectric printing and electrode printing were repeated. The present invention was completed based on the knowledge that the occurrence of dents and voids on the substrate can be prevented by printing to a thickness of .

That is, the gist of the present invention is to apply dielectric paste to a ceramic green sheet, press-bond a ceramic green sheet of the same composition onto the top surface of the dielectric paste, and then sinter the ceramic green sheet with a built-in capacitor. A multilayer ceramic substrate with a built-in capacitor, characterized in that an insulating paste is applied to the surface other than the dielectric paste-coated surface to the same thickness as the dielectric paste, and then a ceramic green sheet is crimped and fired. It's in the manufacturing method.

As the ceramic used for the green sheet material in the present invention, any ceramic can be used as long as it is used in the green sheet multilayer lamination method, but there is a wide selection of conductor materials when firing the circuit board, making fine wiring possible. From this point of view, those used for low fAMA bonded ceramic substrates with a firing temperature of 800 to 1000°C are preferable.

As an insulating powder for such a substrate material, for example, Zn
O-Mg0-AjzOs based powder, 5iOa-Bin3 based glass powder and alumina powder mixed in a predetermined ratio;
PbO-5iO□-B*0s-CaO-based glass powder and alumina powder mixed in a predetermined ratio, CaQ-Aja
03-5iOa-B203 glass powder and alumina powder mixed in a predetermined ratio, MgO-Al2O, -5l
A powder made by mixing Oa-BaOa glass powder and alumina powder in a predetermined ratio.

Ba5n (SO, l powder, etc.) is al.

The dielectric material is not particularly limited, but a dielectric material that can be fired at a temperature of 800 to 1000°C, which approximately matches the firing temperature of the clean sheet, is preferred.

In the method of the invention, the dielectric material forming the capacitor and the insulating material filling around it are each printed.

For printing, a normal screen printing method is used.

The printed film thickness of the dielectric and insulator is controlled by selecting the printing screen mesh, changing the emulsion thickness, and adjusting the solids content of the paste.

It is preferable that the dielectric layer and the surrounding insulating layer have the same thickness as possible, and the gap at the boundary between them is preferably 50 um or less. This is because there is a risk of wire breakage.

When forming a single capacitor, the lower conductor is usually printed on a green sheet, followed by the dielectric, the insulator, and the upper conductor in that order.

This is preferable in terms of the accuracy of the thickness of the dielectric, but more preferably the upper conductor is printed on a green sheet laminated on top, and the upper conductor is laminated on top of the dielectric and insulator printed to the same thickness.

When forming a multilayer capacitor, conductors, dielectrics, and insulators are printed on the lower green sheet, and further conductors, dielectrics, and insulators are printed, and this process is repeated as necessary.

When wiring is carried from the lower conductor to the upper layer, a through hole is provided in the insulating paste printed part. The through holes may be punched out after printing has dried, or they may be formed during printing of the insulating paste.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Ceramic green sheets were prepared by adding a binder and a solvent to powder of alumina and borosilicate glass mixed at a ratio of 50:50 (weight ratio) to form a slurry, and coating the slurry.

The dielectric paste is Pb(Mg+z3Nbazi)03
-PbTiO: + ~ Produced by adding a vehicle to PbO dielectric powder.

The insulation paste is a 50:5 ratio of alumina and borosilicate glass.
It was prepared by adding a vehicle to powder mixed at 0 (weight ratio).

The conductor paste used was a paste prepared by adding a vehicle to Ag-Pdf 15% powder.

1 to 5 show steps in an embodiment of the method for manufacturing a circuit board of the present invention.

Figure 1 shows a top view and a cross-sectional view of a ceramic green sheet l with a thickness of 0.3 mm that forms a dielectric layer, through-holes 2 are drilled in the necessary locations, and the through-holes 2 are then filled with conductive paste. After printing and drying, the wiring conductor 3 was printed. 6 In Fig. 2, the capacitor electrode 4 was printed on the green sheet shown in Fig. 1, and after drying, the thickness was 10.
The dielectric paste 5 was screen-printed on it so that the thickness after drying was 4011 In.

In FIG. 3, an insulating paste 6 was printed on the portion where the dielectric material in FIG. 3 was not printed so that the thickness after drying was 50 μm.

Separately, a green sheet l° having a counter electrode and a wiring conductor similar to that shown in FIG.
They were laminated on the sheet shown in the figure and bonded under heat. After removing the binder from the pressed body, they were integrally fired at 850° C. for 10 minutes to obtain a circuit board 7 with a built-in capacitor having the cross section shown in FIG.

Example 2 The process of printing capacitor electrodes, dielectrics, and insulators in FIG. 2 of Example 1 was repeated, and after drilling through holes in the obtained laminate and connecting each electrode with conductive paste, After laminating the green sheets, thermo-compression bonding, and removing the binder, the circuit board 8 is baked at 850°C for 10 minutes and has a built-in multilayer capacitor as shown in the cross-sectional view of FIG.
I got it.

[Effects of the Invention] In manufacturing a multilayer ceramic substrate with a built-in capacitor, the present invention applies a dielectric paste and an insulating paste to the same thickness on the surface of a ceramic green sheet, and then applies the insulating paste to the areas where the paste is not applied. Since the ceramic green sheets are pressed and fired, each layer of the manufactured multilayer board has no unevenness.Therefore, compared to multilayer boards with many unevenness produced by conventional manufacturing methods, the area where circuit elements can be mounted is expanded. Packaging density can be increased.

[Brief explanation of drawings]

Figures 1 to 5 are explanatory diagrams of the manufacturing process of a circuit board with a built-in capacitor according to an example of the present invention, and Figure 6 is a cross-sectional view of a circuit board with a built-in multilayer capacitor obtained in another example. . FIGS. 7 and 8 are cross-sectional views of substrates obtained by the conventional method. ■= Ceramic green sheet 2 Through hole 3: Wiring conductor 4 Electrode 5/Dielectric paste 6: Insulator paste 7.8 2 Circuit board Applicant: Nippon Cement Co., Ltd., Agent: Patent attorney Atsushi 1) Katsura Part Te 15 - Procedural Shinshu…Author (Method) July 31, 1999

Claims (1)

[Claims] (1) A method for manufacturing a multilayer ceramic substrate with a built-in capacitor, in which a ceramic green sheet (1) is coated with a dielectric paste (5), a ceramic green sheet (1) of the same composition is crimped on the top surface, and then fired. After applying the insulating paste (6) to the same thickness as the dielectric paste on the surface of the green sheet (1) other than the dielectric paste-coated surface, apply the ceramic green sheet (1) to the same thickness as the dielectric paste.
) A method for manufacturing a multilayer ceramic substrate with a built-in capacitor, characterized by crimping and firing.