KR100887112B1 - Method of manufacturing the non-shrinkage ceramic substrate and multilayer ceramin substrate manufactured by the same - Google Patents

Abstract

A manufacturing method of non-shrinkage ceramic substrate and a multilayer ceramic substrate manufactured by the same are provided to minimize damage due to a glass movement between a dielectric sheet and a ceramic laminate in a sintering process. A plurality of dielectric sheet(100) is laminated. The dielectric sheet includes an inner electrode and a conductive via hole. A ceramic laminate is prepared by laminating a buffer layer(101) on at least one surface among a top and a bottom of a laminated structure. A glass content of the buffer layer is higher than a glass content of the dielectric sheet. A sheet for binding is arranged on a top and a bottom of the ceramic laminate, and prevents face direction shrinkage of the dielectric sheet. The ceramic laminate is sintered at a sintering temperature of the dielectric sheet. The sheet for binding is removed from the ceramic laminate.

Description

Method of manufacturing the non-shrinkable ceramic substrate and a multilayer ceramic substrate manufactured thereby {Method of manufacturing the non-shrinkage ceramic substrate and multilayer ceramin substrate manufactured by the same}

The present invention relates to a method for manufacturing a non-shrinkable ceramic substrate and to a multilayer ceramic substrate manufactured thereby, in particular, a non-shrinkable ceramic that can minimize damage caused by glass movement between the restraining dielectric sheet and the ceramic laminate during the firing process. A method of manufacturing a substrate and a multilayer ceramic substrate produced thereby.

In general, a multilayer ceramic substrate is used as a composite component of an active element such as a semiconductor IC chip and a passive element such as a capacitor, an inductor, and a resistor, or a simple semiconductor IC package. More specifically, the multilayer ceramic substrate is widely used to configure various electronic components such as PA module substrates, RF diode switches, filters, chip antennas, various package components, and composite devices.

In order to obtain such a multilayer ceramic substrate, it is necessary to go through a firing process in order to laminate the dielectric sheets on which the wiring conductors are formed and to obtain excellent characteristics, but such a firing process causes shrinkage due to firing of the ceramic. Such shrinkage is less likely to occur uniformly throughout the multilayer ceramic substrate, resulting in dimensional deformation with respect to the plane direction of the ceramic layer.

In addition, shrinkage in the plane direction causes undesired deformation and distortion in the wiring conductors. More specifically, the positional accuracy of the external electrodes for connection of chip components or the like mounted on the multilayer ceramic substrate is reduced, or the wiring Disconnection may occur in a conductor.

As such, shrinkage in the plane direction causes a gap between the conductor patterns and the mounting of components, and it is impossible to mount semiconductor chips such as CSP (Chip Size Package) and MCM (Multi-Chip Modules) with high accuracy. Done. Therefore, in recent years, in manufacturing a multilayer ceramic substrate, it has been proposed to apply a so-called non-shrinkage method to eliminate shrinkage in the surface direction in the firing step.

In general, the non-shrinkage method is applied to manufacture a restraining dielectric sheet using alumina powder, which is a ceramic that is not sintered at 900 ℃ or less, and laminated on the upper and lower parts of the ceramic (LTCC) dielectric sheet capable of low-temperature firing, A method of obtaining a ceramic substrate by applying weight to upper and lower portions of the laminated ceramic substrate and calcining and firing to remove the restraining dielectric sheet.

1A to 1D are cross-sectional views sequentially illustrating a method of manufacturing a non-condensation ceramic substrate according to the prior art.

First, as shown in FIG. 1A, a plurality of dielectric sheets 10 having conductive via holes 30 for connecting internal electrodes 20 and electrodes of different layers are prepared at appropriate positions according to a module circuit diagram. The plurality of dielectric sheets 10 are stacked to form a laminate structure 100.

Next, on the upper and lower surfaces of the laminate structure 100, a restraining dielectric sheet 40, for example, alumina (Al ₂ O ₃ ) sheet, which is not baked at the firing temperature of the dielectric sheet 10, is laminated, and the result Pressurize, plasticize and fire the structure.

Subsequently, as shown in FIG. 1B, the restraining dielectric sheet 40 is removed through a lapping process. In this case, at the interface between the ceramic laminate structure 100 and the restraining dielectric sheet 40 in the firing step, a diffusion layer formed by diffusing a material such as alumina, glass, or binder is formed. Since the diffusion layer is not suitable for forming the external electrode, it is necessary to remove the diffusion layer by the lapping process.

Thereafter, as illustrated in FIG. 1C, the external electrodes 50 connected to the conductive via holes 30 exposed by the lapping process are formed on the upper and lower surfaces of the laminate structure 100 by a known screen printing process. Done.

That is, in order to print the external electrode 50 on the upper and lower surfaces of the laminate structure 100, a screen 60 having a predetermined number of meshes is arranged, and an external electrode is formed on the upper surface of the screen 60. The external electrode 50 is printed by placing Ag, Cu or Ni paste 52 and pushing it through the squeeze 70 to the bottom of the screen.

Finally, the post-firing of the structure is performed in the temperature range of 500 ~ 700 ℃ as a result of the external electrode 50 is printed.

As described above, in the conventional method of manufacturing a non-shrinkable ceramic substrate, a diffusion layer is formed at an interface between the ceramic laminate structure and the restraining dielectric sheet during the firing step. The area of the structure is significantly lower in glass content.

Due to the non-uniformity of the glass content, the strength of the ceramic substrate after firing may be reduced, and furthermore, problems such as a decrease in the bonding strength of the external electrode and a drop in the reliability of falling may be caused.

The present invention is to solve the above problems, an object of the present invention to provide a method of manufacturing a non-contraction ceramic substrate that can minimize the damage caused by the glass movement between the restraining dielectric sheet and the ceramic laminate in the firing process. It is.

Another object of the present invention is to provide a multilayer ceramic substrate produced by the above production method.

In order to achieve the above object, one aspect of the present invention,

Stacking a plurality of dielectric sheets each having internal electrodes and conductive via holes, and having a glass content higher than that of the dielectric sheet on at least one of an upper surface and a lower surface of a structure in which the plurality of dielectric sheets are stacked Stacking a buffer layer formed of a sheet to provide a ceramic laminate, disposing a restraining sheet on the upper and lower surfaces of the ceramic laminate to suppress the contraction in the direction of the dielectric sheet; It provides a method of manufacturing a non-contraction ceramic substrate comprising the step of firing at the firing temperature of the dielectric sheet and the step of removing the restraining sheet from the ceramic laminate.

The buffer layer preferably has a relatively high glass content in order to minimize the damage caused by the glass diffusion during the firing process. Specifically, the glass content of the buffer layer is preferably 60 ~ 80wt%.

In addition, the glass content of the dielectric sheet is preferably 45 to 55wt%.

Preferably, the thickness of the buffer layer may be 2 to 20% of the total substrate thickness in the state in which the restraint sheet is removed after firing.

Additionally, after removing the restraint sheet, the method may further include removing the buffer layer.

In addition, after removing the restraint sheet, the method may further include forming an external electrode to be electrically connected to the inner electrode and the conductive via hole.

In this case, further comprising the step of forming a plating layer on the external electrode.

Specifically, the plating layer is preferably formed by electroless plating Ni and Au sequentially.

On the other hand, the step of firing the ceramic laminate at the firing temperature of the dielectric sheet may be carried out at 800 ~ 900 ℃.

Another aspect of the present invention is a multilayer ceramic substrate produced by the above-described manufacturing method.

In this case, the non-condensation ceramic substrate is preferably a low temperature co-fired ceramic substrate.

According to the present invention, it is possible to obtain a method of manufacturing a non-shrinkable ceramic substrate which can minimize the damage caused by glass movement between the restraining dielectric sheet and the ceramic laminate in the firing process.

As such, by minimizing the damage caused by the glass movement between the restraining dielectric sheet and the ceramic laminate in the firing process, it is possible to expect the effect of improving the strength of the ceramic substrate after firing, improving the bonding strength of the external electrode, and improving the drop reliability.

In addition, according to the present invention, it is possible to obtain a multilayer ceramic produced by the above production method.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

2A to 2E are cross-sectional views of processes sequentially showing a method of manufacturing a non-condensation ceramic substrate according to an embodiment of the present invention.

First, as shown in FIG. 2A, a plurality of dielectric sheets are stacked to prepare ceramic laminates 100 and 101.

Each dielectric sheet constituting the ceramic laminates 100 and 101 may include glass, a binder, a ceramic filler, and the like, and may be provided by a known process, such as a doctor blade process. Specifically, for example, the glass constituting the dielectric sheet is made of SiO ₂ , B ₂ O ₃ , CaO, MgO and the like, the ceramic filler is alumina (Al ₂ O ₃ ) is typical.

Meanwhile, an internal electrode is formed in the dielectric sheets constituting the ceramic laminates 100 and 101, and has conductive via holes formed for electrical connection between the layers.

The internal electrode may be formed of Ag, Cu, Ni, or the like by a screen printing process, and the conductive via hole may be formed by filling a conductive material or plating an inner wall after forming a hole by irradiating a laser to the green sheet. It can be formed through.

In the ceramic laminates 100 and 101, the uppermost layer and the lowermost layer correspond to the buffer layer 101 having a higher glass content than the glass content included in the remaining layers. Although FIG. 2A illustrates the case where both the uppermost layer and the lowermost layer are the buffer layer 101, the buffer layer may be formed only in one of the two layers according to the embodiment.

As described above, the buffer layer 101 has a relatively high glass content. This is a conventional problem in the non-shrinkage process for manufacturing a low-temperature co-fired ceramic substrate, in which the glass is diffused and moved to a restraining sheet containing little glass during the firing process to form a reaction layer at an interface with the restraining sheet. Is to solve.

That is, the glass content of the buffer layer 101 is intentionally higher than the glass content of the remaining dielectric sheets 100 (hereinafter, referred to as a laminate structure of a plurality of dielectric sheets except the buffer layer), and then fired by diffusion of glass. The glass content of the ceramic substrate was then offset.

Accordingly, even if some or all of the buffer layer 101 in contact with the restraining sheet becomes a reaction layer during firing, the content of glass remaining in the buffer layer 101 is still higher than that of the other dielectric sheets 100. Or a similar level, even if it is lower, the difference is not so large that the degradation of substrate performance can be minimized.

Further, when the degree of damage of the buffer layer 101 after firing, in particular, the degree of glass detachment, is deepened, a method of removing the buffer layer 101 may be devised as described below.

In consideration of the function of the buffer layer 101 described above and the preferable glass content after firing, the glass content of the buffer layer 101 is preferably about 60 to 80 wt%. For the purpose of the present invention to minimize performance degradation due to glass separation, the glass content of the buffer layer 101 should be more than 60wt%.

However, when the glass content is increased to 80 wt% or more, the glass diffused from the buffer layer 101 to the restraining sheet is too large, and a part of the restraining sheet is calcined, thereby reducing the shrinkage suppression function, and the restraining sheet is removed after firing. It can be difficult. In addition, the degree of diffusion of the glass is further deepened from the buffer layer 101 to the remaining dielectric sheets 100, and thus plastic imbalance may occur in the stacking direction of the dielectric sheets. The above numerical ranges regarding the glass content of the buffer layer 101 are employed in consideration of these matters.

In addition, the glass content of the remaining dielectric sheets 100 is about 45 ~ 55wt% that can be generally employed.

Next, as shown in FIG. 2B, the restraining sheet 200, for example, alumina (Al ₂ O ₃ ), covers the upper and lower surfaces of the ceramic laminates 100 and 101, and specifically the upper surface of the buffer layer 101. The sheets are laminated to a thickness of 50 to 500 μm.

The restraining sheet 200 is provided to suppress surface shrinkage of the ceramic laminates 100 and 101 and includes a material such as alumina that is not baked at the firing temperature of the ceramic laminates 100 and 101. . In this case, since the alumina content of the restraint sheet 200 is 99% or more in order to have a surface direction shrinkage suppression effect of the dielectric sheet, as described above, the glass is diffused toward the restraint sheet 200 in the firing process. .

Subsequently, the ceramic laminates 100 and 101 are fired in a state where the restraining sheet 200 is disposed. Although FIG. 2C illustrates the post-firing step, the ceramic laminates 100 and 101 are contracted in the thickness direction rather than the surface direction by the non-shrink process.

More specifically, this step will be described in which the ceramic laminates 100 and 101 on which the restraining sheet 200 is disposed are pressurized, calcined, and fired. At this time, firing is preferably performed at about 800 to 900 ° C., which is a general firing temperature of the dielectric sheet. While the firing is in progress, the restraining sheet 200 prevents the dielectric sheets constituting the ceramic laminates 100 and 101 from shrinking in the plane direction.

In this firing process, as shown in FIG. 2C, all or part of the buffer layer 101 is changed into a reaction layer by movement of glass or the like. In this case, as described above, despite the movement of the glass, since the buffer layer 101 has a high glass content, it may still maintain the glass content level of the remaining dielectric sheets 100.

Next, as shown in FIG. 2D, the restraining sheet is removed from the ceramic laminate in which baking is completed.

The restraining sheet 200 may be removed by a generally known lapping process. Furthermore, in the present embodiment, even the buffer layer 101 is removed, and the removal of the buffer layer 101 may be employed when the degree of glass detachment from the buffer layer 101 is severe during firing.

On the other hand, if the glass layer of the buffer layer 101 is not so much that it is included in the final ceramic substrate, and there is no problem in performing the function, the buffer layer 101 may not be removed. In this case, the buffer layer 101 may also be removed. The wiring pattern, that is, the internal electrode and the conductive via hole may be formed in advance.

In this case, the thickness of the buffer layer 101 is about 2 to 20% based on the entire multilayer ceramic substrate from which the restraining sheet is removed after firing.

When the thickness of the buffer layer 101 corresponds to 2% or less of the thickness of the entire multilayer ceramic substrate, the manufacturing process is also difficult, and the effect by the buffer function is not large.

In addition, when the ratio of the thickness of the buffer layer 101 to the thickness of the entire multilayer ceramic substrate is 20% or more, the firing temperature may increase due to the increase of the overall glass content and plastic unevenness may occur in the thickness direction, resulting in deterioration of product performance. .

Lastly, as shown in FIG. 2E, an outer electrode 50 is formed in the outermost dielectric sheet of the ceramic laminate 100 to be electrically connected to the inner electrode and the conductive via hole. Although not shown, a plating layer may be formed on the external electrode 50. For example, the plating layer may be formed by electroless plating Ni and Au sequentially.

3 is a cross-sectional view illustrating a multilayer ceramic substrate provided by another aspect of the present invention.

Referring to FIG. 3, the multilayer ceramic substrate is a low temperature co-fired ceramic substrate, in which a plurality of dielectric sheets having internal electrodes and conductive via holes are stacked.

The multilayer ceramic substrate may be manufactured by the manufacturing method described with reference to FIG. 2. However, unlike the case of FIG. 2, the buffer layer 101 is not removed, and thus, the glass is removed from the buffer layer 101 during the firing process. It can be understood as a case where the amount is not large.

In this case, as described above, the external electrode 50 is formed on the buffer layer 101, and a wiring pattern is also formed on the buffer layer 101 for electrical connection with the external electrode 50.

Of course, unlike the form illustrated in FIG. 3, a structure in which the buffer layer 101 is removed may be possible according to the manufacturing method of FIG. 2.

The multilayer ceramic substrate provided by the present invention solves the problem of lowering the glass content of the ceramic laminate after the firing process by disposing a buffer layer having a particularly high glass content at the interface between the dielectric sheet laminate and the restraining sheet. Thereby, the effect of the strength improvement of the ceramic substrate after baking, the adhesive strength improvement of an external electrode, and the fall reliability improvement can be anticipated.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

1A to 1D are cross-sectional views sequentially illustrating a method of manufacturing a non-condensation ceramic substrate according to the prior art.

2A to 2E are cross-sectional views of processes sequentially showing a method of manufacturing a non-condensation ceramic substrate according to an embodiment of the present invention.

3 is a cross-sectional view illustrating a multilayer ceramic substrate provided by another aspect of the present invention.

<Description of the symbols for the main parts of the drawings>

100 dielectric layer laminated structure 101 buffer layer

200: restraining sheet 103: silicon core layer

10: dielectric sheet 20: internal electrode

30: conductive via hole 50: external electrode

Claims (11)

Stacking a plurality of dielectric sheets each having an internal electrode and a conductive via hole; Preparing a ceramic laminate by stacking a buffer layer formed of a dielectric sheet having a glass content higher than that of the dielectric sheet on at least one of an upper surface and a lower surface of a structure in which the plurality of dielectric sheets are stacked; Disposing a restraining sheet on each of the upper and lower surfaces of the ceramic laminate to suppress the shrinkage in the surface direction of the dielectric sheet; Firing the ceramic laminate at the firing temperature of the dielectric sheet; And Removing the restraining sheet from the ceramic laminate; Method for producing a non-shrinkable ceramic substrate comprising a. The method of claim 1, The glass content of the buffer layer is a manufacturing method of a non-contraction ceramic substrate, characterized in that 60 ~ 80wt%. The method of claim 1, Glass content of the dielectric sheet is a manufacturing method of a non-contraction ceramic substrate, characterized in that 45 ~ 55wt%. The method of claim 1, The thickness of the buffer layer is a method for manufacturing a non-contraction ceramic substrate, characterized in that 2 ~ 20% of the total substrate thickness in the state that the restraining sheet is removed after firing. The method of claim 1, And after removing the restraint sheet, further comprising removing the buffer layer. The method of claim 1, After removing the restraint sheet, And forming an outer electrode to be electrically connected to the inner electrode and the conductive via hole. The method of claim 6, The method of manufacturing a non-shrinkable ceramic substrate further comprising the step of forming a plating layer on the external electrode. The method of claim 7, wherein The plating layer is a method for producing a non-shrinkable ceramic substrate, characterized in that formed by electroless plating Ni and Au in order. The method of claim 1, The firing of the ceramic laminate at the firing temperature of the dielectric sheet is carried out at 800 ~ 900 ℃ manufacturing method of a non-shrink ceramic substrate. A multilayer ceramic substrate produced by the method of any one of claims 1 to 9. The method of claim 10, The non-contraction ceramic substrate is a multi-layer ceramic substrate, characterized in that the low temperature co-fired ceramic substrate.

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