KR20060013950A - Method for manufacturing multilayer substrate using dissimilar dielectric material - Google Patents

Abstract

The present invention relates to a method for manufacturing a multilayer board using a heterogeneous dielectric, and has a fixed capacitance using a paste made of a low-temperature fired ceramic having a high dielectric constant on a multi-layer substrate manufactured by using a low-temperature fired ceramic green sheet having a low dielectric constant. In addition to the multilayering process of forming a capacitance layer, microconductors are formed using photosensitive conductor paste on a green sheet, a fired thick film, or a fired substrate, and a high dielectric constant low-temperature fired ceramic paste is also photosensitive. The circuit structure is further integrated by minimizing the warpage of the substrate.

Heterogeneous, dielectric, high dielectric constant, photosensitive, paste

Description

Method for manufacturing multilayer substrate using dissimilar dielectric material

1A to 1B show a first embodiment according to the present invention;

2A to 2D show a second embodiment according to the present invention.

Explanation of symbols on the main parts of the drawings

100, 200: low dielectric constant multilayer board

110, 210: high dielectric constant dielectric layer

The present invention relates to a method for manufacturing a multi-layer substrate using heterogeneous dielectrics while minimizing warpage or cracking of the substrate while using heterogeneous dielectrics, and further minimizing the overall structure by integrating the circuit structure.

In general, low temperature co-fired ceramics (LTCC) have high frequency characteristics and can incorporate passive elements such as resistors, inductors, and capacitors inside the module, and have a firing temperature of 1000 ° C. or lower. Gold, silver, copper, etc., which have high conductivity, can be used as internal electrodes, which can reduce the loss caused by the electrodes.At the same time, laminated ceramic modules using LTCC have painted powders for low temperature firing. After the sheet is produced, it is produced through the steps of punching, paste printing, lamination, and baking.

The characteristics of LTCC are generally low in dielectric constant of less than 10. LTCC with low permittivity is suitable for high speed signal processing such as CPU because it is advantageous for high speed data communication. As it is difficult to realize a fixed capacitance within a limited volume, it is usually replaced by a mounting method of chip components without taking advantage of the LTCC which can incorporate passive components.

In order to make up for such drawbacks, researches have recently been conducted to embed capacitors of high capacitance by stacking and co-firing heterogeneous materials having different permittivity.

Combining low dielectric constant and high dielectric constant materials has attracted much attention as a research subject because signal processing is fast and the capacitor can be fixed in a limited area so that the size can be further reduced.

However, when co-firing dissimilar materials, it is not easy to avoid occurrence of warpage or crack after firing due to mismatch of shrinkage behavior, mismatch of coefficient of thermal expansion, etc., and various constraints in materials and processes. .

In particular, the warpage of the heterogeneous substrate due to shrinkage mismatch is very difficult to solve. In order to control this, the low dielectric constant sheet and the high dielectric constant sheet are laminated in a sandwich structure so as to balance stress during firing or alumina on both sides of the laminate. A method of firing by adding a non-shrinkable layer such as a sheet has been proposed, but the process is complicated and has many difficulties, and there is a problem in controlling warping.

Meanwhile, in the manufacture of laminated ceramic module substrates, the 3D circuit pattern is generally implemented by punching, via filling, and screen printing of the green sheet. However, due to the limitation of the resolution of the conductive wire which can be realized by the general screen printing method, which is about 80 μm, the further miniaturization is no longer accelerated.

In order to cope with this, a method of realizing a fine thick film wire using photosensitive conductor paste has been developed. This is a method of implementing a circuit pattern by applying a photosensitive paste to the green sheet and then exposing it using ultraviolet light through a photomask, and spraying a developing solution thereon to remove the uncured portion. When using this method, it is possible to form a thick film wire of 50 μm or less on the substrate, and further miniaturization can be expected. In the case of the photosensitive dielectric paste, the microvia can be realized in a similar manner, but since the high dielectric constant LTCC material has not been released, it is not applied to the heterogeneous composite.

As the trend of miniaturization of components continues, there is a limit to the implementation of small chips in the stacking process using low dielectric constant, and the simultaneous firing technology of heterogeneous green sheets to solve this problem does not show its advantages due to the difficulty of controlling the shrinkage rate. I can't. In addition, due to the characteristics of the thick film printing process, since the resolution of the conductive wire is about 80 μm, it is difficult to realize a conductive wire having a smaller line width, and the yield is usually significantly reduced.

Therefore, there is a need for an improved method for preventing warpage due to mismatch of shrinkage rate and further minimizing the circuit pattern to further increase the level of miniaturization of the module or the substrate.

Accordingly, the present invention was developed to solve the above problems, while using heterogeneous dielectrics to minimize warpage or crack of the substrate, and to further miniaturize the entire module by integrating the circuit structure further, multi-layer using heterogeneous dielectrics. Its purpose is to provide a substrate manufacturing method.

In accordance with this object, the present invention provides a multi-layered process of forming a capacitance layer having a high capacitance using a paste made of low-temperature calcined ceramic having a high dielectric constant on a multi-layer substrate fabricated using a low-temperature calcined ceramic green sheet having a low dielectric constant. In addition, microconductors are formed using a photosensitive conductor paste on a green sheet, a fired thick film, or a fired substrate, and microvias are formed using a photosensitive conductor having a high dielectric constant low temperature calcined ceramic paste. Minimize the circuit structure to a minimum.

To this end, the present invention,

Forming a multi-layer substrate having a low dielectric constant;

A second process of forming a high-k dielectric layer on the low-k dielectric substrate;                         

The second process is;

Disclosed is a method of manufacturing a multilayer substrate using a heterogeneous dielectric, wherein a dielectric layer having a high dielectric constant is formed of a high dielectric constant photosensitive dielectric paste on the low dielectric constant multilayer substrate formed in the first process.

And, in another invention,

Forming a multi-layered substrate having a low dielectric constant patterned with a three-dimensional first partial circuit pattern by using a low dielectric constant sheet and a conductive paste for simultaneous firing;

A second process of forming a three-dimensional second partial pattern on the low dielectric constant multilayer board formed in the first process to electrically couple with the three-dimensional first partial circuit pattern to realize a predetermined circuit board; Consist of;

The second process is;

A step 2-1 of forming a high dielectric constant photosensitive dielectric paste film on the low dielectric constant multilayer substrate formed in the first step;

Step 2-2 of forming a predetermined via pattern by patterning the high-k photosensitive dielectric paste film formed in step 2-1;

Manufacturing a multi-layered substrate using a heterogeneous dielectric, characterized in that to form a three-dimensional second partial pattern including the second to third process of filling the via pattern formed in the via pattern in the second-2 process the post-baking conductor paste. The method is disclosed.

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

First Embodiment

First, the first embodiment of the present invention is to form a dielectric layer using a high dielectric constant photosensitive paste on a multilayer ceramic substrate fabricated using a low dielectric constant green sheet, more specifically to form a low dielectric constant multilayer substrate A high dielectric constant dielectric layer is formed on the low dielectric constant multilayer ceramic substrate, and a high dielectric constant dielectric layer is formed of a high dielectric constant photosensitive dielectric paste, which will be described in more detail with reference to FIGS. 1A to 1B.

First, as shown in Figure 1a, according to the first embodiment of the present invention, the low dielectric constant low-temperature calcined ceramic powder having a dielectric constant of about 10 or less by tape casting to make a green sheet, cut to a predetermined size, multi-layer Via-holes are punched in each layer according to a predetermined pattern to form the structure, and the conductor paste is filled in the punched via-holes to electrically connect the layers.

Next, each green sheet is sequentially stacked according to a desired circuit pattern and baked at about 850 ° C. for about 20 minutes. As a result, a predetermined multilayer substrate 100 made of a low dielectric constant low temperature calcined ceramic is completed.

Subsequently, as shown in FIG. 1B according to the present invention, a dielectric layer 110 made of a low-temperature fired ceramic layer having a high dielectric constant of about 30 or more is formed on the completed multilayer substrate 100.

In more detail, first, a photosensitive paste is manufactured by using a high dielectric constant low-temperature plastic ceramic powder. The photosensitive paste is inherent in a vehicle made by mixing a binder polymer having a carboxylic acid, a monomer, a photoinitiator, and an organic solvent. The electrification ceramic powder is mixed and pulverized and dispersed with three rollers to complete the production.

Thereafter, the completed photosensitive dielectric paste is applied onto the low dielectric constant multilayer board 100 and dried in an oven at about 80 ° C. to form a photosensitive dielectric paste film.

Next, the pattern for forming vias is exposed using ultraviolet rays and a photomask. At this time, the region to which ultraviolet rays are irradiated by the action of the monomer and the photoinitiator is cured, and the other regions are not cured.

On the other hand, after exposure, vias are formed in the paste film by developing the exposed photosensitive dielectric paste film using Na ₂ CO ₃ 1% aqueous solution. It is preferable that the via size is 100 micrometers or less in diameter here.

Finally, after development, washing and drying, and firing at 850 ℃ for about 10 minutes to form a high-k dielectric layer 110 according to the present invention in which vias are formed, resulting in the co-firing of heterogeneous green sheets Easy warping or cracking of the substrate is reduced in the high dielectric constant dielectric layer according to the present invention.

Second Embodiment

Next, a second embodiment according to the present invention is an additional three-dimensional by using a high-k dielectric photosensitive dielectric paste and a post-baking conductor paste on a multi-layer ceramic substrate composed of a three-dimensional circuit using a low dielectric constant green sheet and a conductive paste for co-firing It is about implementing a circuit structure.

More specifically, a low dielectric constant multi-layer substrate having a patterned three-dimensional first partial circuit pattern is formed using a low dielectric constant sheet and a conductive paste for co-firing, and on top of the formed low dielectric constant multilayer substrate, three-dimensional Forming a three-dimensional second partial pattern electrically coupled with the first partial circuit pattern of the substrate to form a predetermined circuit board, and then forming a high-k photosensitive dielectric paste film on the multi-layer substrate having a low dielectric constant. A high dielectric constant photosensitive dielectric paste film is patterned to form a predetermined via pattern, and a series of processes of filling a via pattern with a post-baking conductor paste are repeatedly performed to form a three-dimensional second partial pattern. Hereinafter, an example will be described with reference to FIGS. 2A to 2D.

First, the low dielectric constant low temperature calcined ceramic powder is cast into a green sheet, cut into an appropriate size suitable for the process, punched via holes in each layer according to a predetermined via pattern to form a multilayer structure, and punched vias. The conductor paste is filled into the holes to electrically connect the layers. At this time, the pattern is implemented through screen printing or thick film lithography process to form a lead, a resistor, a capacitor, an inductor, etc. for the circuit configuration of the three-dimensional first partial pattern.

In particular, for high integration of the module, it is preferable to minimize the size of the conductive wire and the inductor by using a thick film lithography process, and to use a screen printing process that is easy to process in areas where fine wires such as resistors or capacitors are not required. The pattern formation method according to the thick film lithography process will be described in more detail as follows.

That is, after the photosensitive thick film conductor paste is printed using a blank screen without a special pattern on the green sheet, it is dried in an oven at about 80 ° C. to form a photosensitive conductor paste film. After exposing a predetermined pattern by using a pattern, the uncured region is removed through a developing process, washed with distilled water, and then sufficiently dried in an oven to form a fine circuit pattern on the green sheet.

Meanwhile, when the green sheets having the circuit patterns formed thereon are laminated and calcined at about 850 ° C. for about 20 minutes, the multilayer substrate 200 using the low dielectric constant low temperature calcined ceramic is completed.

Then, a high dielectric constant low temperature calcined ceramic layer is formed on the completed multilayer substrate 200 according to the present invention.

Specifically, a photosensitive paste is manufactured by using a high dielectric constant low temperature plastic ceramic powder. The photosensitive paste is a high dielectric constant ceramic powder in a vehicle made by mixing a binder polymer having a carboxylic acid with a monomer, a photoinitiator, and an organic solvent. It is produced by mixing the mixture, and grinding and dispersing it with three rollers.

The photosensitive dielectric paste thus prepared is applied onto the low dielectric constant multilayer board 200 and dried in an 80 ° C. oven to form a photosensitive dielectric paste film 210.

Subsequently, a pattern for forming vias is exposed using ultraviolet rays and a photomask 300 (FIG. 2B), in which the region to which ultraviolet rays are irradiated by the action of the monomer and the photoinitiator is cured, and the other regions are not cured. .

Next, via A is formed on the paste film by developing the exposed paste film using an aqueous solution of Na ₂ CO ₃ (FIG. 2C) (FIG. 2D), where the size of the via A is 100 μm in diameter. It is preferable that it is the following. After development, washing and drying are performed, and then fired at 850 ° C. for about 10 minutes to form a high dielectric constant dielectric layer having vias (FIG. 2D).

The conductive layer is formed on the finished dielectric layer by using a screen printing or thick film lithography process and baked at about 850 ° C. for about 10 minutes to realize a predetermined second partial pattern electrically connected to the first partial pattern. At this time, when printing or applying the conductor paste, the paste can fill the vias of the dielectric layer so as to finally be electrically connected between the layers.

The high dielectric constant low temperature calcined ceramic layer is formed by repeating the high dielectric constant dielectric forming step and the conductor layer forming step, and the process is lengthened by a continuous process. It is preferable to make it about the following.

As described above, through the multilayering process of the high dielectric constant low temperature calcined ceramic, vias having a size that cannot be realized by screen printing can be formed to increase the circuit integration degree, and high dielectric constant ceramics can be used to achieve low dielectric constant ceramics. Capacitors with difficult fixed capacitances or capacitors with much smaller volumes in the same capacity can be implemented, which also increases circuit density.

In addition, it is preferable to use a low dielectric constant low-temperature fired ceramic having a low difference between the low dielectric constant ceramic and the coefficient of thermal expansion, and in order to suppress the characteristic change during the refiring of the low dielectric constant substrate, the firing of the high dielectric constant ceramic is a low dielectric constant ceramic. It is preferable to make it as short as possible under the baking temperature.

As described in detail above, the method of manufacturing a multilayer substrate using a heterogeneous dielectric according to the present invention minimizes warpage or cracking of a substrate that is likely to occur in simultaneous firing of a heterogeneous dielectric green sheet, and enables a highly integrated module to be implemented. In addition, by forming the conductive wire and the inductor using a thick film lithography process, it is possible to increase the degree of integration of the circuit in the unit volume, thereby miniaturizing the entire device.

Although the invention has been described in detail only with respect to the specific examples described, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (4)

Forming a multi-layer substrate having a low dielectric constant; A second process of forming a high-k dielectric layer on the low-k dielectric substrate; The second process is; The high dielectric constant photosensitive dielectric paste is formed on the multi-layer substrate having a low dielectric constant formed in the first step, and a high dielectric constant dielectric layer is formed. The method of claim 1, wherein the second process comprises: A step 2-1 of forming a predetermined photosensitive dielectric paste film by applying and drying a photosensitive paste made of a high dielectric constant low temperature plastic ceramic on the low dielectric constant multilayer substrate formed in the first step; And forming a high-k dielectric layer by patterning the high-k photosensitive dielectric paste film formed in step 2-1 according to a predetermined via pattern. Substrate manufacturing method. Forming a multi-layered substrate having a low dielectric constant patterned with a three-dimensional first partial circuit pattern by using a low dielectric constant sheet and a conductive paste for simultaneous firing; A second process of forming a three-dimensional second partial pattern on the low dielectric constant multilayer board formed in the first process to electrically couple with the three-dimensional first partial circuit pattern to realize a predetermined circuit board; Consist of; The second process is; A step 2-1 of forming a high dielectric constant photosensitive dielectric paste film on the low dielectric constant multilayer substrate formed in the first step; Step 2-2 of forming a predetermined via pattern by patterning the high-k photosensitive dielectric paste film formed in step 2-1; Multi-layered substrate using a heterogeneous dielectric, characterized in that to form a three-dimensional second partial pattern, including the second to third step of filling the via pattern formed in the step 2-2 and the post-baking conductor paste. Manufacturing method. The method of claim 3, further comprising: after the 2-3; Forming a photosensitive dielectric paste film having a high dielectric constant on the entire region including an upper portion of the via pattern filled with the post-fired conductive paste; A step 2-5 of forming a predetermined via pattern by patterning the high-k photosensitive dielectric paste film formed in step 2-4; The second pattern of filling the via pattern formed in step 2-5 with the post-baking conductor paste is sequentially repeated at least twice, to form a three-dimensional second partial pattern. , Multi-layer substrate manufacturing method using heterogeneous dielectric.

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