KR101963274B1 - Multi-layer ceramic substrate and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a multilayer ceramic substrate and a method of manufacturing the same, wherein the multilayer ceramic substrate according to the present invention comprises: a ceramic layer composed of a first surface layer, a second surface layer, and an inner layer sandwiched between the first surface layer and the second surface layer; And a surface layer electrode formed of a spherical metal powder on an exposed surface of the first surface layer or the second surface layer, wherein the first and second surface layers are formed of a first spherical ceramic powder, and the inner layer is a leaf- .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic substrate,

The present invention relates to a multilayer ceramic substrate and a manufacturing method thereof.

In recent years, there has been a demand for a ceramic package that can reliably realize characteristics in a high frequency band, facilitate heat dissipation and surface mounting, and have high reliability in products, together with light-weight shortened chips such as RF, IC, sensor chip and X-TAl LED.

In order to cope with such a ceramic package, a package is required in which the internal patterns are well aligned, the electrode filling rate of the via electrode is sufficiently secured, the warpage is small, and the interval between the patterns is constant.

Particularly, the bonding strength between the ceramic substrate and the external pattern electrode is very important for the reliability of the ceramic package.

For this purpose, matching of shrinkage behavior and interfacial bonding strength during firing of different materials such as substrates for ceramic composition, electrodes for external pattern formation, and electrodes for via filling should be ensured. In addition, the structure of the electrode and the composition of the ceramic substrate are also important.

Japanese Laid-Open Patent Publication No. 2012-031040

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multilayer ceramic substrate which can improve the bonding strength between a ceramic layer and an electrode layer and improve warpage.

It is another object of the present invention to provide a method for manufacturing a multilayer ceramic substrate which can control shrinkage, increase plasticity and warp during simultaneous firing of ceramics and electrodes.

SUMMARY OF THE INVENTION The object of the present invention is to provide a multilayer ceramic substrate in which the ceramic layer and the surface layer electrode are co-fired to produce a multilayer ceramic substrate, the mismatching of the dissimilar materials reduces the adhesion strength between the ceramic layer and the electrode layer, So as to prevent bending deformation.

For this purpose, of the layers constituting the ceramic layer, the upper and lower surface layers are formed of sphere-shaped ceramic powders, and the inner layer interposed between the upper and lower surface layers is formed of a ceramic layer formed of leaf- Layer ceramic substrate so as to include a multi-layer ceramic substrate.

At this time, the surface layer formed of the spherical ceramic powder contributes to improvement of the adhesion strength with the surface layer electrode and control of the shrinkage rate during firing, and the inner layer formed of the leaf ceramic powder contributes to the thin film implementation and strength enhancement.

Further, the occurrence of warpage of the substrate can be suppressed by the constitution of such a ceramic layer.

In addition, the inner layer of the ceramic layer may further include a spherical ceramic powder having an average particle size smaller than that of the surface layer, so that the plastic density can be further improved.

The ceramic layer may further include a sub inner layer formed of spherical ceramic powder having an average particle size smaller than that of the surface layer between adjacent inner layers, thereby improving interfacial bonding strength between the ceramic layer and the via electrode.

Even if the multilayer ceramic substrate according to the present invention is formed by co-firing by the ceramic layer controlling the shape of the powder constituting each layer, the adhesion strength between the ceramic layer and the surface layer electrode is excellent, the occurrence of warpage of the substrate is suppressed, great.

Further, according to the present invention, it is possible to manufacture a ceramic substrate using a lower firing temperature than that of the prior art by reducing the pores in the green sheet by the green sheet for the ceramic layer containing the leaf-type ceramic powder.

1 is a cross-sectional view of a multilayer ceramic substrate according to a first embodiment of the present invention.
2 is a cross-sectional view of a multilayer ceramic substrate according to a second embodiment of the present invention.
3 is a cross-sectional view of a multilayer ceramic substrate according to a third embodiment of the present invention.
4 to 7 are process drawings illustrating a method of manufacturing a multilayer ceramic substrate according to a first embodiment of the present invention,
4 is a sectional view after forming the ceramic green sheet,
5 is a cross-sectional view after the via electrode is formed,
6 is a cross-sectional view after the surface layer electrode is formed,
7 is a cross-sectional view after co-firing.
8 to 11 are process drawings illustrating a method of manufacturing a multilayer ceramic substrate according to a third embodiment of the present invention,
8 is a sectional view after forming the ceramic green sheet,
9 is a sectional view after the via electrode is formed,
10 is a cross-sectional view after the surface layer electrode is formed,
11 is a cross-sectional view after co-firing.

The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as excluding the presence or addition of the mentioned forms, numbers, steps, operations, elements, elements and / It is not.

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The terms first, second, etc. in this specification are used to distinguish one element from another element, and the element is not limited by the terms.

Hereinafter, a multilayer ceramic substrate and a method of manufacturing the same according to the present invention will be described in detail with reference to FIGS. 1 to 11. FIG.

1 is a cross-sectional view of a multilayer ceramic substrate according to a first embodiment of the present invention.

1, the multilayer ceramic substrate 100 according to the first embodiment of the present invention includes a ceramic layer 110 and a surface layer electrode 120 formed on both surfaces of the ceramic layer 110, And a via electrode 130 in the ceramic layer 110. The ceramic layer 110, the surface electrode 120, and the via electrode 130 are formed by co-firing.

The surface electrode 120 may be used as a connection terminal for electrical connection with an electronic component to be mounted on the multilayer ceramic substrate 100 or for electrical connection with an external terminal.

The surface electrode 120 may be formed of one or more metals selected from a conductive material such as copper (Cu), silver (Ag), platinum (Pt), or an alloy thereof.

The surface electrode 120 may be formed of a spherical metal powder 122 having an average particle size of about 0.5 to 2 mu m. Here, the spherical metal powder 122 includes spherical metal alloy powder.

Although the surface layer electrodes 120 formed on both surfaces of the ceramic layer 110 are shown in FIG. 1, the present invention is not limited thereto. The formation positions and the number of the surface layer electrodes 120 may be formed on the multilayer ceramic substrate 100, The number of the ceramic layers 110 may be variously changed depending on the design of the ceramic layer 110. FIG.

The ceramic layer 110 is a multilayer ceramic sheet in which a plurality of sheet sheets are stacked and includes first and second surface layers 110a and 110b arranged in an up and down direction and first and second surface layers 110a and 110b 110a, and 110b, respectively.

With this configuration, the ceramic layer 110 has a laminated structure composed of the first surface layer 110a, the inner layer 110c, and the second surface layer 110b in order from the top.

The ceramic layer 110 having such a constitution is obtained by firing together with the surface layer electrode 120 the ceramic green sheet for inner layer between the upper and lower surface layer ceramic green sheets and the upper and lower surface layer ceramic green sheets, Respectively.

Among the layers constituting the ceramic layer 110, the first and second surface layers 110a and 110b are layers exposed to the outside and in contact with the surface layer electrode 120. [

Typically, ceramics and metals have different coefficients of expansion (CTE). Therefore, when the ceramic layer and the metal layer are co-fired, warpage deformation of the substrate may occur due to mismatching due to difference in shrinkage ratio between the different materials during firing, It is known that the bonding strength between the ceramic layer and the metal layer is lowered due to the stress inherent in the interface between the ceramic layer and the metal layer.

Accordingly, the present invention has been modified in the structure of the ceramic layer 110 to improve the problems caused by mismatching due to co-firing of different materials, and a specific application example thereof will be described below.

The surface layers 110a and 110b that are in contact with the surface electrode 120 among the layers constituting the ceramic layer 110 are formed of the spherical metal powder 122 constituting the surface electrode 120, And is formed of spherical ceramic powder 112 having the same shape.

The spherical ceramic powder 112 constituting the surface layers 110a and 110b forms a grain boundry with the spherical metal powder 122 constituting the surface electrode 120 during sintering, The spherical metal powder 122 is bonded to the spherical ceramic powder 112 by increasing the total area.

As a result, the bonding strength between the ceramic layer 110 and the surface layer electrode 120 is increased by the spherical ceramic powder 112, so that the bonding strength between the ceramic layer 110 and the surface layer electrode 120 can be improved.

The spherical ceramic powder 112 may have a difference in average particle size from the spherical metal powder 122 within 5 占 퐉 from the viewpoint of increasing the area of the spherical metal powder 122 and controlling the shrinkage ratio. Within this range, the spherical ceramic powder 112 may have an average particle size equal to or greater than or equal to the spherical metal powder 122.

When the average particle size of the spherical ceramic powder 112 satisfies the above-described range, plastic densification of the surface layers 110a and 110b becomes possible at the time of firing, so that the effect of low shrinkage control becomes possible. On the other hand, if the average particle size of the spherical ceramic powder 112 exceeds the above range, the bonding strength between the ceramic layer 110 and the surface electrode 120 may be lowered.

For example, the spherical ceramic powder 112 preferably has an average particle size of 0.5 to 2 mu m, more preferably an average particle size of 0.8 to 1.2 mu m.

In addition, the spherical ceramic powder 112 may be a general oxide or nitride used as a high temperature co-fired ceramic (HTCC) material. For example, alumina (Al ₂ O ₃ ) .

The inner layer 110c which is not in contact with the surface layer electrode 120 is formed of a leaf-shaped ceramic powder 114, unlike the surface layers 110a and 110b, which constitute the ceramic layer 110. [

The shape of the leaf-shaped ceramic powder 114 is more advantageous than that of the spherical ceramic powder 112 because the porosity of the leaf-like ceramic powder 114 can be reduced, thereby making the film more dense. Therefore, the inner layer 110c composed of the leaf-shaped ceramic powder 114 is superior in plastic densification due to the reduction in voids than the surface layers 110a and 110b made of the spherical ceramic powder 112, so that the strength of the multilayer ceramic substrate 100 is improved Can contribute more.

The leaf-type ceramic powder 114 may be a general oxide or nitride used as HTCC material, for example, alumina (Al ₂ O ₃ ) which is easy to manufacture as a leaf type.

For example, alumina having a major axis length of 3 to 10 mu m and a thickness of 0.1 to 0.3 mu m may be used as the leaf-type ceramic powder 114, but the present invention is not limited thereto.

The ceramic layer 110 thus formed is uniformly sintered and shrunk by the inner layer 110c having a relatively high plastic density to prevent the occurrence of warpage, thereby making it possible to manufacture a substrate having a uniform flatness.

Since the porosity in the inner layer 110c is reduced by the leaf-shaped ceramic powder 114, the ceramic layer 110 can be manufactured at a firing temperature in the range of 1300 ° C to 1400 ° C, which is lower than the conventional temperature range of 1500 ° C to 1600 ° C .

The ratio of each of the powders 112 and 114 constituting the surface layers 110a and 110b and the inner layer 110c in the ceramic layer 110 is not particularly limited. However, from the viewpoints of an improvement in plastic density and an improvement in warpage, 70 to 90% of the surface layers 110a and 110b and 10 to 30% of the inner layer 110c with respect to the total area of the inner layer 110.

At this time, if the ratio of the surface layer 110a or 110b is less than 70% or the ratio of the inner layer 110c is less than 10%, it is difficult to control the shrinkage behavior upon firing, and it may be difficult to secure a sufficient bonding strength. On the other hand, if the ratio of the surface layer 110a or 110b exceeds 90% or the ratio of the inner layer 110c exceeds 30%, the increase in material cost is caused only by the leaf ceramic powder which is relatively expensive without further improvement in bonding strength .

The via electrode 130 penetrates the ceramic layer 110 and is electrically connected to the surface layer electrode 120.

The via electrode 130 may be formed of one or more metals or alloys thereof selected from a conductive material such as copper (Cu), silver (Ag), platinum (Pt), and the like.

The via electrode 130 may be formed of a spherical metal powder (not shown) having an average particle size of about 0.2 to 0.3 탆 for improving the filling density.

Although only the via electrode 130 is shown in the ceramic layer 110 for convenience of description, the ceramic layer 110 may include a conductive pattern (not shown) used as an inner layer circuit layer or a pad, The via electrode 130 may be formed to penetrate through the respective layers of the ceramic layer 110 to electrically connect the conductive pattern to the surface electrode 120. In this case,

It can be seen from the above description that the multilayer ceramic substrate 100 has excellent bonding strength between the ceramic layer 110 and the surface layer electrode 120. That is, the multilayer ceramic substrate 100 can suppress the delamination defects in which the ceramic layer 110 and the surface electrode 120 are separated due to the improvement in the interfacial adhesion between the ceramic layer 110 and the surface layer electrode 120 Thereby preventing deterioration of the multilayer ceramic substrate 100 due to high temperature and high humidity, thereby improving the reliability of the product.

The ceramic layer 110 of the multilayer ceramic substrate 100 is formed of the spherical ceramic powder 112 and the spherical ceramic powder 114 so that the sintered compact density can be improved and the package with the thick plastic thickness can be produced. And has the characteristics of a sintered body.

The multilayer ceramic substrate 100 thus constructed can realize plastic shrinkage rate and pattern accuracy, thereby making it possible to fabricate a large area ceramic substrate and package, thereby securing a degree of design freedom for manufacturing an RF module, a sensor module, and a package.

2 is a cross-sectional view of a multilayer ceramic substrate according to a second embodiment of the present invention.

Referring to FIG. 2, the multilayer ceramic substrate 100a according to the second embodiment of the present invention is partially different in the structure of the multilayer ceramic substrate 100 of FIG. 1 and the inner layer 110c of the ceramic layer 110.

However, in the multilayer ceramic substrate 100a, the configuration and effects of the remaining surface layers 110a and 110b, the surface electrode 120 and the via electrode 130, except for the structure of the inner layer 110c of the ceramic layer 110, Layer ceramic substrate 100 shown in FIG. 1, so that a duplicate description will be omitted and only differences will be described later.

In the second embodiment of the present invention, among the layers constituting the ceramic layer 110, the inner layer 110c not in contact with the surface electrode 120 is formed by mixing the leaf-shaped ceramic powder 114 and the spherical ceramic powder 116 .

The spherical ceramic powder 116 is added to reduce the pores generated in the inner layer 110c by the spherical ceramic powder 114. The spherical ceramic powder 116 has a larger average particle size than the spherical ceramic powder 112 contained in the surface layers 110a and 110b. It is preferable to use one having a small size.

The average particle size of the spherical ceramic powder 116 is not particularly limited, but it is possible to use an average particle size of 0.2 to 0.3 占 퐉 from the viewpoint of inter-particle void reduction.

In addition, the inner layer 110c can further improve the compactness by appropriately adjusting the mixing ratio of the leaf-shaped ceramic powder 114 and the spherical ceramic powder 116.

The spherical ceramic powder 116 may be a general oxide or nitride used as the HTCC material, and may be alumina (Al ₂ O ₃ ), which is easy to form, for example.

The ceramic layer 110 constructed as shown in FIG. 2 can be fabricated at a firing temperature of 1300 ° C. to 1400 ° C., which is lower than the conventional temperature of 1500 ° C. to 1600 ° C., because the voids between the particles are minimized in the inner layer 110c. 130 and the ceramic layer 110 is improved.

3 is a cross-sectional view of a multilayer ceramic substrate according to a third embodiment of the present invention.

Referring to FIG. 3, the multilayer ceramic substrate 100b according to the third embodiment of the present invention includes a sub-inner layer 110d between adjacent inner layers 110c, 100a.

However, in the multilayer ceramic substrate 100b, the constitution and effects of the remaining surface layers 110a and 110b, the surface electrode 120 and the via electrode 130, except for the sub inner layer 110d, are the same as those of the multilayer ceramic substrate 100, and the structure and the effect of the inner layer 110c may be the same as those of the multilayer ceramic substrate 100a of FIG. 2 described above, so that redundant description will be omitted and only differences will be described later.

In the third embodiment of the present invention, among the layers constituting the ceramic layer 110, the sub-inner layer 110d formed on the same layer as the inner layer 110c is composed of the spherical ceramic powder 112 contained in the surface layers 110a and 110b ) Of spherical ceramic powder 118 having a smaller average particle size.

In a multilayer ceramic substrate manufactured by laminating a plurality of ceramic green sheets, a plurality of via holes are formed for electrical connection of each interlayer circuit, and the inside thereof is filled with a conductive electrode material.

However, if the ceramic green sheet shrinks more in the main surface direction than the thickness direction during firing, the via electrode may protrude outward after firing, and pores may be formed in the main surface of the via hole. By this pore, The interfacial bonding force between the electrodes can be deteriorated.

In the third embodiment of the present invention, the sub inner layer 110d formed of the spherical ceramic powder 118 is formed between the inner layers 110c adjacent to each other, thereby reducing the air gap in the vicinities of the via electrodes 130, 130 and the ceramic layer 110 can be improved.

Although the average particle size of the spherical ceramic powder 118 is not particularly limited, it is preferable to use the spherical ceramic powder 118 having an average particle size of about 0.2 to 0.3 mu m in terms of improving the adhesion strength between the sub inner layer 110d and the via electrode 130 .

The spherical ceramic powder 118 may be a general oxide or nitride used as a HTCC material, and may be alumina (Al ₂ O ₃ ), which is easy to form, for example.

The ceramic layer 110 having the structure as shown in Fig. 3 includes upper and lower surface layer ceramic green sheets, a plurality of inner layer ceramic green sheets interposed between the upper and lower surface layer ceramic green sheets, and a plurality of inner layer ceramic green sheets A plurality of intervening ceramic green sheets for in-layer lamination are fused and formed by firing.

A method of manufacturing a multilayer ceramic substrate according to the present invention constructed as shown in FIG. 1 will now be described with reference to FIGS.

4 is a cross-sectional view of the multilayer ceramic substrate according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view after forming the ceramic green sheet, FIG. 5 is a cross- Fig. 7 is a cross-sectional view after co-firing. Fig.

As shown in FIG. 4, the method for manufacturing the multilayer ceramic substrate of the present embodiment first prepares ceramic green sheets 110a ', 110b', and 110c 'for constituting a ceramic layer.

At this time, the ceramic green sheets 110a 'and 110b' are ceramic green sheets for the surface layer, each of which is spherical ceramic powder 112 having an average particle size of 0.5 to 2 占 퐉, preferably 0.8 to 1.2 占 퐉 ), A binder and a solvent are mixed to prepare a paste, the paste is coated on a carrier film by a doctor blade method or the like, and dried to form a sheet having a thickness of several millimeters.

The ceramic green sheet 110c 'is a ceramic green sheet for inner layer, which is prepared by mixing a leaf-type ceramic powder 114 having a major axis length of 3 to 10 占 퐉 and a thickness of 0.1 to 0.3 占 퐉, a binder and a solvent, This paste may be coated on a carrier film by a doctor blade method or the like and dried to form a sheet having a thickness of several mm.

Next, as shown in Fig. 5, the area where the via electrodes 130 (see Fig. 7) of each of the ceramic green sheets 110a ', 110b', 110c 'are to be formed is formed by using a laser drill, After the via hole V is formed by etching, the via hole V is filled with a conductive paste to form a via electrode paste layer 130 '.

At this time, the conductive paste may be composed of a spherical metal powder having an average particle size of about 0.2 to 0.3 μm, an organic binder, and a solvent.

In this step, the thickness and angle of each green sheet 110a 'and 110b' are adjusted so that the ratio of the inner layer ceramic green sheet 110c 'to the surface layer ceramic green sheets 110a' and 110b 'can be 70 to 90% The content of the ceramic powder contained in the green sheet, and the like can be appropriately controlled.

6, a conductive paste is printed on one surface of the ceramic green sheets 110a 'and 110b' for surface layer to form a surface layer paste 120 'for a surface electrode composed of the spherical metal powder 122 do.

At this time, the conductive paste may be composed of a spherical metal powder having an average particle size of about 0.5 to 2 μm, an organic binder, and a solvent.

Next, as shown in FIG. 7, an inner layer ceramic green sheet 110b 'is formed between the surface layer ceramic green sheets 110a' and 110b '(see FIG. 6) so that the surface layer electrode paste layer 120' (See FIG. 6), the surface layer electrode paste layer 120 '(see FIG. 6) and the via-electrode paste (see FIG. 6) after interposing the ceramic green sheets 110a', 110b ' The layer 130 '(see FIG. 6) is simultaneously fired at a temperature of 1300 ° C to 1400 ° C.

In this case, the ceramic green sheets 110a ', 110b', 110c ', see FIG. 6), the surface layer paste layer 120' (see FIG. 6) and the via electrode paste layer 130 ' These processes are simultaneously fired and shrunk, and this process is referred to as co-firing process.

The ceramic green sheets 110a ', 110b' and 110c 'of FIG. 6 are fused and fired by the co-firing process to form a laminate of the first surface layer 110a, the inner layer 110c and the second surface layer 110b from above. Is formed of a sintered ceramic layer (110). 6) and the via-electrode paste layer 130 '(see FIG. 6) are fired to form the surface-layer electrode 120 and the via-electrode 130. The paste layer 120' Thus, the multilayer ceramic substrate 100 is fabricated.

During the co-firing process, densification is performed at the interface between the ceramic layer 110 and the surface electrode 120, thereby improving the bonding strength.

In this step, firing may be insufficient when the firing process is performed at a temperature lower than 1300 ° C., and may be increased only when the firing temperature is higher than 1400 ° C. regardless of the firing effect.

The present invention relates to a ceramic green sheet for internal layer (110c ') (see FIG. 4) composed of a leaf-type ceramic powder 114, and as the pores in the sheet are reduced, Simultaneous firing at temperature is possible.

Even if the ceramic layer 110 and the surface layer electrode 120 are formed by co-firing, the multilayer ceramic substrate 100 of this embodiment manufactured by such a construction and manufacturing method has a high bonding strength between the ceramic layer 110 and the surface layer electrode 120 And is a high-strength substrate having relatively small flexural deformation.

The multilayer ceramic substrate 100 thus constructed can realize plastic shrinkage rate and pattern accuracy, thereby making it possible to fabricate a large area ceramic substrate and package, thereby securing a degree of design freedom for manufacturing an RF module, a sensor module, and a package.

2, the multilayer ceramic substrate 100a according to the present invention includes a ceramic green sheet 110c 'for inner layer in FIG. 4 having a length of 3 to 10 mu m and a thickness of 0.1 to 0.3 mu m, The remaining process is the same as the process described above with reference to FIGS. 4 to 7 except that a sheet is prepared using a paste including a leaf-type ceramic powder 114 having a particle size of 0.2 to 0.3 μm and a spherical ceramic powder having an average particle size of 0.2 to 0.3 μm. They are omitted because they may be the same.

A method of manufacturing a multilayer ceramic substrate according to the present invention constructed as shown in FIG. 3 will now be described with reference to FIGS. 8 to 11 as follows.

8 to 11 are sectional views after forming a ceramic green sheet, FIG. 9 is a cross-sectional view after forming a via electrode, and FIG. 10 is a cross-sectional view of a multilayer ceramic substrate according to a third embodiment of the present invention. Fig. 11 is a cross-sectional view after co-firing. Fig.

As shown in FIG. 8, the method for manufacturing a multilayer ceramic substrate of the present embodiment first prepares ceramic green sheets 110a ', 110b', 110c ', and 110d' for constituting a ceramic layer.

Next, as shown in FIG. 9, a via hole V is formed in a region where the via electrodes 130 (see FIG. 11) of each of the ceramic green sheets 110a ', 110b', 110c ', and 110d' After that, the paste layer 130 'for a via electrode is formed by filling a conductive paste into the inside of the via hole (V).

10, a conductive paste is printed on one surface of the surface ceramic green sheets 110a 'and 110b' to form a surface layer paste 120 'for a surface layer electrode made of the spherical metal powder 122 do.

Next, as shown in FIG. 11, a plurality of inner layer ceramics 110a 'and 110b' are formed between the surface layer ceramic green sheets 110a 'and 110b' (see FIG. 10) so that the surface layer electrode paste layer 120 ' The ceramic green sheets 110a ', 110b', 110c ', and 110d', see FIG. 10) are alternately interposed between the green sheet 110c '(see FIG. 10) (See FIG. 10) and the via-electrode paste layer 130 '(see FIG. 10) are simultaneously baked at a temperature of 1300 ° C to 1400 ° C.

According to the manufacturing method of Figs. 8 to 11, the constitution of the inner layer ceramic green sheet 110c 'is different from that of Fig. 8, and the sub inner layer ceramic green sheet 110d' is additionally formed, A via hole V is formed in the ceramic green sheet for a layer 110d 'and a ceramic green sheet 110d' for a sublayer is disposed between the ceramic green sheets for internal layer 110c 'in FIG. 10 and FIG. The manufacturing method according to the rest of the configuration may be the same as the method described above with reference to FIGS. 4 to 7, so that a duplicate description will be omitted.

The ceramic green sheet 110c 'shown in FIG. 8 is a ceramic green sheet for inner layer, which comprises a leaf-shaped ceramic powder 114 having a major axis length of 3 to 10 μm and a thickness of 0.1 to 0.3 μm and an average particle size of 0.2 to 0.3 The spherical ceramic powder 116, the binder and the solvent are mixed to prepare a paste, this paste is coated on a carrier film by a doctor blade method or the like, and then dried to form a sheet having a thickness of several millimeters.

The ceramic green sheet 110d 'is a sub-in-layer ceramic green sheet for reducing voids in the area adjacent to the via electrode 130 (see FIG. 11). The ceramic green sheet 110d' is composed of a spherical ceramic powder 118 having an average particle size of 0.2 to 0.3 μm, To prepare a paste. This paste is coated on a carrier film by a doctor blade method or the like, followed by drying to form a sheet having a thickness of several millimeters.

The ceramic green sheets 110a ', 110b', 110c 'and 110d', see FIG. 10), the surface layer paste layer 120 '(see FIG. 10) and the via layer paste layer 130' , See Fig. 10) are simultaneously fired and contracted at the same time.

The ceramic green sheets 110a ', 110b', 110c ', and 110d' shown in FIG. 10 are fused while being fired to form a first surface layer 110a, an inner layer 110c or a sub-inner layer 110d, The ceramic layer 110 composed of the laminate of the surface layer 110b and the inner layer 110c and the sublayer 110d are formed. 10) and the via-electrode paste layer 130 '(see FIG. 10) are fired to form the surface-layer electrode 120 and the via-electrode 130. The paste layer 120' Thus, the multilayer ceramic substrate 100b is fabricated.

At this time, the bonding strength between the ceramic layer 110 and the via electrode 130 can be further improved as compared with the multilayer ceramic substrate 100 of FIG.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

One. Manufacture of specimens

Example

94% by weight of spherical alumina (Al ₂ O ₃ ) powder having an average particle size of 1.0 μm was mixed with 6% by weight of chlorinated polyethylene (CPE) and coated on a substrate by a doctor blade method to prepare a ceramic green sheet for surface layer Lt; / RTI >

94% by weight of leaf-like alumina (Al ₂ O ₃ ) powder having a major axis length of 3 μm and a thickness of 0.2 μm was mixed with 6% by weight of CPE and coated on a substrate by a doctor blade method to prepare a 0.03 mm- Layer ceramic green sheet was prepared.

A paste containing 80% by weight of Ag powder was printed on one surface of two sheets of ceramic green sheets for surface layer to form a surface layer electrode having a thickness of 8 to 10 탆, and the average particle size of spherical silver (Ag) powder was 1.0 탆.

Thereafter, the inner layer ceramic green sheet was placed between the two ceramic green sheets for the surface layer so that the surface electrode was exposed, and then fired in an oven maintained at 1300 ° C to 1400 ° C for 1 hour to obtain a multilayer ceramic substrate having a total thickness of 0.25 mm .

Comparative Example

90 wt% of spherical Al ₂ O ₃ powder having an average particle size of 20 μm was mixed with 10 wt% of chlorinated polyethylene (CPE) and coated on a substrate by a doctor blade method to prepare a ceramic green sheet having a thickness of 0.2 mm.

Thereafter, a paste containing 80 wt% Ag powder was printed on one surface of two sheets of ceramic green sheets for surface layer to form a surface layer electrode having a thickness of 8 to 10 mu m, the average particle size of spherical silver (Ag) powder being 1.0 mu m .

Thereafter, the resultant was fired in an oven maintained at 1500 ° C to 1600 ° C for 1 hour to prepare a multilayer ceramic substrate having a total thickness of 0.25 mm.

2. Property evaluation

The shrinkage percentage, flexural strength, flexural strength and adhesion strength of the ten specimens A1 to A10 selected from among the same specimens prepared according to the examples and the ten specimens B1 to B10 selected from the same specimens prepared according to the comparative example were evaluated, Are shown in Table 1 below.

Each evaluation method is as follows.

<Shrinkage ratio>

The change rate of x, y dimension after firing was evaluated. (Where x is the width and y is the height).

&Lt; Bending strength >

Point bending strength test.

&Lt; Evaluation of flexure &

After firing, the difference between the maximum substrate thickness and the minimum substrate thickness was evaluated.

&Lt; Adhesion strength &

The multilayer ceramic substrate manufactured on the PCB was mounted and reflowed, and then the shear test was performed to evaluate the strength of the surface layer electrode when it was peeled off from the PCB.

Psalter Shrinkage rate
(%) Bending strength
(GPa) warp
(mm) Adhesion strength
(Kgf / cm2) Psalter Shrinkage rate
(%) Bending strength
(GPa) warp
(mm) Adhesion strength
(Kgf / cm2) A1 18.00 654 0.007 52.4 B1 16.50 437 0.0499 42.3 A2 18.10 642 0.007 41.0 B2 16.80 594 0.0338 14.0 A3 17.90 567 0.007 51.7 B3 15.80 486 0.0729 28.3 A4 18.00 585 0.009 51.9 B4 16.80 502 0.0481 34.0 A5 18.20 542 0.008 41.0 B5 17.00 401 0.0517 38.7 A6 18.10 582 0.007 57.5 B6 16.10 676 0.0493 12.6 A7 18.20 590 0.008 45.2 B7 15.70 480 0.025 12.0 A8 18.30 620 0.012 49.1 B8 15.60 524 0.038 25.0 A9 18.10 635 0.008 59.3 B9 16.00 589 0.0373 26.3 A10 18.20 589 0.008 53.9 B10 16.40 530 0.032 28.7 Average 18.11 600.60 0.008 50.3 Average 16.27 521.90 0.044 26.2 Deviation 0.12 35.78 0.002 6.28 Deviation 0.50 80.82 0.014 10.67

Referring to Table 1, the specimens A1 to A10 produced according to the embodiment of the present invention had higher density, higher average bending strength and average bonding strength than the specimens B1 to B10 prepared according to the comparative example , And the warpage was significantly low.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, and that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention. However, it should be understood that such substitutions, changes, and the like fall within the scope of the following claims.

100, 100a, 100b: multilayer ceramic substrate
110: ceramic layer 110a: first surface layer
110b: second surface layer 110c: inner layer
110d: Sub-
112, 116 and 118: spherical ceramic powder
114: leaf-shaped ceramic powder 120: surface layer electrode
122: spherical metal powder 130: via electrode
V: Via hole

Claims (14)

A ceramic layer composed of a first surface layer, a second surface layer, and an inner layer sandwiched between the first surface layer and the second surface layer; And
And a surface layer electrode formed of a spherical metal powder on an exposed surface of the first surface layer or the second surface layer,
Wherein the first and second surface layers are formed of a first spherical ceramic powder and the inner layer is formed of a leaf-type ceramic powder.
The method according to claim 1,
Wherein the ceramic layer and the surface layer electrode are co-fired.
The method according to claim 1,
Wherein the inner layer has a higher plastic density than the first and second surface layers.
The method according to claim 1,
Wherein the first spherical ceramic powder has an average particle size difference with the spherical metal powder of 5 m or less.
The method according to claim 1,
Wherein the sum of the areas of the first and second surface layers is 70 to 90% of the total area of the ceramic layer and the ratio of the inner layer is 10 to 30% of the total area of the ceramic layer.
The method according to claim 1,
Wherein the ceramic layer further includes a via electrode electrically connected to the surface layer electrode.
The method according to claim 6,
Wherein the inner layer further comprises a second spherical ceramic powder having an average particle size smaller than that of the first spherical ceramic powder.
8. The method of claim 7,
Wherein the ceramic layer further includes a sub-inner layer in which a via electrode is formed between the adjacent inner layers,
Wherein the sub inner layer is formed of a third spherical ceramic powder having an average particle size smaller than that of the first spherical ceramic powder.
Preparing ceramic green sheets for a surface layer formed of a first spherical ceramic powder and ceramic green sheets for an inner layer formed of a leaf ceramic powder;
Forming a surface layer paste layer formed of a spherical metal powder on one surface of the surface ceramic green sheets; And
And simultaneously firing the interlayer ceramic green sheet between the ceramic green sheets for the surface layer so that the surface layer paste layer is exposed.
10. The method of claim 9,
Wherein the co-firing is performed at 1300 to 1400 占 폚.
10. The method of claim 9,
Before forming the surface layer paste layer,
And forming a via electrode paste layer on the ceramic green sheets for the surface layer and the ceramic green sheets for the inner layer.
10. The method of claim 9,
The step of preparing the ceramic green sheet for inner layer
And a second spherical ceramic powder having an average particle size smaller than that of the first spherical ceramic powder.
13. The method of claim 12,
In the step of preparing the inner layer ceramic green sheet,
Further comprising a ceramic green sheet for a sub-layer including a via-electrode forming region in the same layer as the ceramic green sheet for inner layer,
Wherein the sub-layer ceramic green sheet is formed of a third spherical ceramic powder having an average particle size smaller than that of the first spherical ceramic powder.
14. The method of claim 13,
Before forming the surface layer paste layer,
And forming a paste layer for a via electrode on the ceramic green sheet for sub-in-layer.

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