KR100956212B1 - Manufacturing method of multilayer ceramic substrate - Google Patents

Abstract

Disclosed is a method of manufacturing a multilayer ceramic substrate. According to the present invention, a method of manufacturing a multilayer ceramic substrate may include preparing a ceramic laminate by stacking a plurality of ceramic green sheets including via electrodes, and on a via electrode exposed through any one of an upper surface and a lower surface of the ceramic laminate. Forming an electrode pad on the ceramic laminate; surrounding the side of the electrode pad on the ceramic laminate; laminating a surface-shaped green sheet higher than the electrode pad; and firing the ceramic laminate on which the surface-shaped green sheet is laminated. When the baking is completed, forming a nickel plating layer to have a height parallel to the surface-shaped green sheet on the electrode pad, and forming a gold plating layer on the nickel plating layer.

LTCC, Ceramic, Surface Shape Green Sheet

Description

Manufacturing method of multilayer ceramic substrate {Manufacturing method of multi-layer substrate}

The present invention relates to a method for manufacturing a multilayer ceramic substrate, and more particularly, to a method for manufacturing a multilayer ceramic substrate for improving flatness and adhesion strength of an external electrode.

Low Temperature Co-fired Ceramic (LTCC) substrate fabrication technology is used to provide a device for implementing a given circuit in a number of green sheet layers based primarily on glass-ceramic materials. Implemented by the screen printing process using a metal with excellent conductivity, and by stacking each layer and simultaneously firing ceramic and metal conductors to manufacture a multi-chip module (MCM) and a multi-chip package (multi-chip package).

Low-temperature co-fired ceramic (LTCC) technology has the advantage of implementing passive elements such as resistors, inductors, and capacitors in the module according to the process characteristics that enable simultaneous firing of ceramics and metals. Make it possible.

1 is a view showing a conventional multilayer ceramic substrate. Referring to FIG. 1, the multilayer ceramic substrate 10 may include a ceramic laminate 1, a via electrode 2, an internal electrode 3, and an external electrode including a plurality of ceramic green sheets 1a, 1b, 1c, and 1d. It includes (4). In this case, the plurality of ceramic green sheets 1a, 1b, 1c, and 1d are laminated and baked at a temperature of about 700 to 900 ° C. The via electrode 2 and the internal electrode 3 are formed in the ceramic green sheets 1a, 1b, 1c, and 1d. In addition, referring to an enlarged view of a part of the multilayer ceramic substrate 10, the external electrode 4 includes an electrode pad 4c, a first plating layer 4b, and a second plating layer 4a.

On the other hand, the external electrode 4 is formed in the part where the via electrode 2 is exposed among the ceramic green sheets 1a and 1d of the uppermost layer and the lowermost layer. Specifically, the external electrode 4 is bonded to the interface of the uppermost or lowermost ceramic green sheets 1a and 1d, thereby protruding from the upper or lower surface of the ceramic green sheet. Thus, the bonding strength of the external electrode 4 falls by the structure in which only one surface of the external electrode 4 is joined with the ceramic green sheet.

In addition, when the external electrode 4 is formed after firing the ceramic laminate 1, the adhesion strength between the ceramic laminate 1 and the external electrode 4 is further lowered. In order to solve this problem, a method of simultaneously firing the ceramic laminate 1 and the external electrode 4 is also considered, but this method is difficult to secure flatness, and the first plating layer 4b constituting the external electrode 4 and It was difficult to obtain uniform characteristics when forming the second plating layer 4a.

On the other hand, when the multilayer ceramic substrate 10 is chemically treated (for example, a plating process, an etching process, or a clinic process), the electrode pads 4c and the electrode pads are formed between the ceramic green sheet 1d and the electrode pads 4a. Chemicals penetrate between the first plating layer 4b and between the first plating layer 4b and the second plating layer 4a, thereby causing a defect in the product.

In addition, when the multilayer ceramic substrate 10 is soldered onto a printed circuit board (not shown), the multilayer ceramic substrate 10 is not soldered at the correct position by the protruding external electrode 4 structure, and thus bonding according to the mounting is performed. Defects will occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to form a plating layer for forming an external electrode in contact with a surface-shaped green sheet of a ceramic material, whereby the adhesion strength of the external electrode can be improved. It is for providing a method for producing a ceramic substrate.

Still another object of the present invention is to provide a method for producing a multilayer ceramic substrate, which can improve product yield and is easy to mount by forming external electrodes in parallel with the interface of the ceramic substrate.

Method of manufacturing a multilayer ceramic substrate according to an embodiment of the present invention for achieving the above object, the step of preparing a ceramic laminate by stacking a plurality of ceramic green sheet including a via electrode, the ceramic laminate Forming an electrode pad on the via electrode exposed through either one of an upper surface and a lower surface, surrounding the side surface of the electrode pad on the ceramic laminate, and forming a surface-shaped green sheet higher than the electrode pad. Laminating, firing the ceramic laminate in which the surface-shaped green sheet is laminated, and when the baking is completed, forming a nickel plating layer on the electrode pad to have a height parallel to the surface-shaped green sheet; Forming a gold plating layer on the nickel plating layer.

In this case, the surface-shaped green sheet is preferably made of the same shrinkage behavior during firing of the plurality of ceramic green sheets.

In addition, the electrode pad is preferably formed to a lower thickness than the surface forming portion green sheet.

In the manufacturing method, the nickel plating layer and the gold plating layer may be formed using an electrolytic plating method or an electroless plating method.

According to the present invention, by forming a surface-shaped green sheet around the external electrode to increase the bonding area of the external electrode and the ceramic substrate, it is possible to improve the bonding strength of the external electrode. In addition, product defects caused by chemical treatment can be reduced.

In addition, since a part of the external electrode is formed in a form embedded in the ceramic substrate, when soldering and bonding to the printed circuit board it is possible to prevent the bonding failure caused by the position deformation of the external electrode.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

2A to 2E are schematic views illustrating a method of manufacturing a multilayer ceramic substrate according to an embodiment of the present invention. Referring to FIG. 2A, a plurality of ceramic green sheets 11a, 11b, 11c, and 11d are stacked to form a ceramic laminate 11. Specifically, an organic binder, a dispersant, and a mixed solvent are added to the glass-ceramic powder and then dispersed using a ball mill. The slurry thus obtained is filtered through a filter, then defoamed and a ceramic green sheet having a predetermined thickness is formed by using a doctor blade method.

The via electrode 12 may be formed by filling a conductive paste by forming a via hole in each of the ceramic green sheets 11a, 11b, 11c, and 11d. In addition, the internal electrode 12 can be formed by applying a conductor paste to a portion of each of the ceramic green sheets 11a, 11b, 11c, and 11d on which the via electrode 12 is formed. The ceramic laminate 11 is prepared by laminating a plurality of ceramic green sheets 11a, 11b, 11c, and 11d manufactured in this manner.

Although FIG. 2A illustrates a ceramic laminate 11 in which only four ceramic green sheets 11a, 11b, 11c, and 11d are stacked for convenience of description, the number of ceramic green sheets constituting the ceramic laminate is as required. May be increased.

Thereafter, as shown in FIG. 2B, an electrode pad 14a is formed on the ceramic laminate 11. The electrode pad 14a is formed by applying a metal paste containing a metal powder as a main component and a binder, a solvent, and the like to a portion of the ceramic laminate 11 where the via electrode 12 is exposed. In this case, the electrode pad 14a may be formed to a thickness of about 7 to 20 μm.

In addition, the metal powder constituting the electrode pad 14a may be a metal capable of co-firing with the ceramic laminate 11. As a representative example, silver (Ag) may be used.

Next, as shown in FIG. 2C, the surface-shaped green sheets 20a and 20b are laminated on the upper and lower surfaces of the ceramic laminate 11. In this case, the surface-shaped green sheets 20a and 20b are preferably made of the same material as the ceramic green sheets constituting the ceramic laminate 11. Specifically, it may be prepared using a slurry in which an organic binder, a dispersant, and a mixed solvent are added to the same glass-ceramic powder as the plurality of ceramic green sheets 11a, 11b, 11c, and 11d. After the ceramic green sheet is manufactured in this manner, the surface-shaped green sheets 20a and 20b may be formed by removing the region corresponding to the electrode pad 14a. Accordingly, when the surface-shaped green sheets 20a and 20b are laminated on the ceramic laminate 11, the surface-shaped green sheets 20a and 20b are laminated in a form surrounding the side surfaces of the electrode pads 14a. It becomes possible. In this case, the surface-shaped green sheets 20a and 20b should be formed to have a thickness higher than that of the electrode pads 14a. Thereafter, when the surface-shaped green sheets 20a and 20b are laminated on the ceramic laminate 11, the ceramic laminate 11 is fired at a temperature of about 700 to 900 ° C.

On the other hand, as shown in Figure 2d, when baking is completed, in order to protect the electrode pad 14a from the outside, a nickel plating layer 14b is formed on the electrode pad 14a. In this case, the nickel plating layer 14b may be formed using an electrolytic plating method or an electroless plating method. Accordingly, the nickel plating layer 14b may be formed in contact with the surface-shaped green sheets 20a and 20b having a thickness higher than that of the electrode pad 14a. In addition, the nickel plating layer 14b may be formed to have a height parallel to the surface-shaped green sheets 20a and 20b. That is, the height in which the nickel plating layer 14b is formed on the electrode pattern 14a may be the same as that of the surface-shaped green sheets 20a and 20b. In this case, the nickel plating layer 14b may be formed to a thickness of 3 ~ 7㎛.

 Thereafter, as shown in FIG. 2E, a gold plating layer 14c is formed on the nickel plating layer 14b. In this case, the gold plating layer 14c functions as the external electrode 14 on the multilayer ceramic substrate 100 together with the electrode pad 14a and the nickel plating layer 14b.

In addition, the gold plating layer 14c may be formed using an electrolytic plating method or an electroless plating method, and may be formed to a thickness of about 0.1 to 0.3 μm. In this case, even if the gold plated layer 14c is formed on the nickel plated layer 14b, since the thickness thereof is relatively thin compared to the nickel plated layer 14b, the gold plated layer 14c is substantially the surface-shaped green sheet 20a, Parallel to 20b).

As described above, the external electrode 14 including the electrode pad 14a, the nickel plating layer 14b, and the gold plating layer 14c in the multilayer ceramic substrate 100 is formed by the surface-shaped green sheets 20a and 20b. By being formed in the shape surrounded by the side surface, the bonding area with the surface-shaped green sheet 20a, 20b increases, and adhesive strength increases. In addition, the electrode pad 14a of the external electrode 14 is co-fired with the ceramic laminate 11 and the surface-shaped green sheets 20a and 20b to increase the fixing strength.

In addition, the external electrode 14 is formed to be embedded in the multilayer ceramic substrate 100 to have a structure substantially parallel to the interface of the surface-shaped green sheets 20a and 20b. Accordingly, even if the multilayer ceramic substrate 100 is chemically treated, the nickel plated layer 14b and the gold plated layer are formed between the surface of the ceramic laminate 11 and the electrode pad 14a, between the electrode pad 14a and the nickel plated layer 14b. Chemicals do not penetrate between (14c), and product defects can be prevented. In addition, when the multilayer ceramic substrate 100 is solder-bonded on a printed circuit board (not shown), the height variation of the external electrode 14 does not occur, and the bonding state is good.

While the above has been shown and described with respect to preferred embodiments of the invention, the invention is not limited to the specific embodiments described above, it is usually in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a view showing a conventional multilayer ceramic substrate,

2A to 2E are views for explaining a method of manufacturing a multilayer ceramic substrate according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100 multilayer ceramic substrate 11: ceramic laminate

12: via electrode 14: external electrode

14a: electrode pad 14b: nickel plated layer

14c: gold plated layer

Claims (4)

Stacking a plurality of ceramic green sheets including via electrodes to prepare a ceramic laminate; Forming an electrode pad on a via electrode exposed through one of an upper surface and a lower surface of the ceramic laminate; Stacking a surface-shaped green sheet surrounding the side surface of the electrode pad and higher than the electrode pad on the ceramic laminate; Firing the ceramic laminate in which the surface-shaped green sheets are stacked; When the baking is completed, forming a nickel plating layer on the electrode pad to have a height parallel to the surface-shaped green sheet; And, Forming a gold plating layer on the nickel plating layer. The method of claim 1, The surface-shaped green sheet is a method of manufacturing a multilayer ceramic substrate, characterized in that the shrinkage behavior during firing of the plurality of ceramic green sheets is made of the same material. The method of claim 1, The electrode pad is a method of manufacturing a multilayer ceramic substrate, characterized in that formed in a lower thickness than the surface forming portion green sheet. The method of claim 1, The nickel plating layer and the gold plating layer is a method of manufacturing a multilayer ceramic substrate, characterized in that formed using an electroless plating method or an electroless plating method.

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