KR20090105704A - Printed circuit board having embedded capacitors and method of manufacturing the same - Google Patents

Abstract

PURPOSE: A capacitor embedded printed circuit board and a manufacturing method thereof are provided to obtain high dielectric characteristic due to a thermal process of a low temperature. CONSTITUTION: A base substrate(11) includes an internal circuit layer with a lower electrode(12a) and a circuit pattern. A dielectric layer(13a) made of the metal oxide with copper and an upper electrode(14a) are formed in a part of the lower electrode. An insulation resin layer(17) is stacked on the base substrate to bury the lower electrode, the dielectric layer and the upper electrode. An external circuit layer(18) is formed in the insulation resin layer.

Description

Printed circuit board having embedded capacitors and method of manufacturing the same

The present invention relates to a capacitor-embedded printed circuit board and a method of manufacturing the same. In more detail, the present invention improves the adhesion between the electrode and the dielectric layer by configuring the dielectric layer of the capacitor with a metal oxide containing copper, has excellent reliability, and has a built-in capacitor that exhibits high dielectric constant by relatively low temperature heat treatment. A printed circuit board and a method of manufacturing the same.

Until now, the surface of most printed circuit boards is equipped with a general discrete chip resistor or a general discrete chip capacitor. Recently, a printed circuit board incorporating passive elements such as resistors or capacitors has been developed.

This passive element embedded printed circuit board technology refers to a technology that replaces the role of the existing chip resistors and chip capacitors by inserting passive elements such as resistors or capacitors into the outer or inner layers of the substrate using new materials and processes. In other words, the passive printed circuit board is a passive element, for example, a capacitor is buried in the inner layer or the outside of the substrate itself, the capacitor is a passive element of the printed circuit board irrespective of the size of the substrate itself. If integrated into a circuit, this is referred to as an "embedded capacitor" and such a substrate is called a capacitor-embedded printed circuit board. The most important feature of such a capacitor-embedded printed circuit board is that it does not need to be mounted on the substrate surface because the capacitor is inherently provided as part of the printed circuit board.

Hereinafter, a description will be given of a capacitor embedded printed circuit board according to the prior art.

First, there is a method of implementing a polymer thick film type capacitor that applies a polymer capacitor paste and heat cures, that is, dries to form a capacitor. This method produces a built-in capacitor by applying a polymer capacitor paste to an inner layer of a printed circuit board, and then printing and drying the paste to form an electrode after drying it.

Second, a method of implementing an individual embedded capacitor by coating a ceramic filling photosensitive resin on a printed circuit board has been introduced. In this method, after the photosensitive resin containing ceramic powder is coated on a substrate, copper foils are laminated to form respective upper electrodes and lower electrodes, and then circuit patterns are formed and the photosensitive resin is etched to implement individual capacitors.

The built-in capacitor according to the prior art described above can reduce the area occupied by the chip capacitor since the capacitor is inserted into the substrate, thereby increasing the mounting density of the chip and eliminating the need to mount the chip capacitor on the surface. There is. In addition, by using the built-in capacitor, the problem that caused the parasitic component of the device at a high frequency to cause electrical parasitic components to reduce the electrical performance of the product and the reliability of the product due to the increase in the number of connections through soldering, etc. By reducing the connection length of the liver to reduce the electrical parasitic components can improve the electrical performance.

However, in the case of a capacitor embedded printed circuit board according to the prior art, the material used for the embedded capacitor is a polymer material or a form filled with ceramic in a photosensitive resin, so it is suitable to be applied to the printed circuit board process, but to cope with the role of the chip capacitor. There is a problem that the dielectric capacitance value is insufficient, and the adhesion between the dielectric layer and the electrode is poor and thus the reliability is lowered.

Accordingly, in the present invention, extensive research has been conducted to solve the above problems. As a result, the dielectric layer of the built-in capacitor is composed of a metal oxide containing copper, thereby solving the problem of adhesion between the electrode and the dielectric layer, even by a relatively low temperature heat treatment. It has been found that the desired dielectric properties can be obtained, and the present invention has been completed based on this.

Accordingly, an aspect of the present invention is to provide a capacitor-embedded printed circuit board having a high adhesive force between an electrode and a dielectric layer and a method of manufacturing the same.

Another aspect of the present invention is to provide a capacitor-embedded printed circuit board and a method of manufacturing the same, which can achieve desired dielectric properties without deformation of the resin substrate.

According to a preferred embodiment of the present invention, a method of manufacturing a capacitor-embedded printed circuit board includes:

(a) preparing a base substrate having an inner circuit layer on one surface including a lower electrode and a circuit pattern;

(b) forming a dielectric layer comprising a metal oxide containing copper on a portion of the lower electrode, and an upper electrode;

(c) laminating an insulating resin layer on the base substrate such that the lower electrode, the dielectric layer and the upper electrode are embedded; And

(d) forming an outer circuit layer on the insulating resin layer;

Characterized in that it comprises a.

In the manufacturing method, the base substrate may be a single-sided printed circuit board, a double-sided printed circuit board or a multilayer printed circuit board.

The metal oxide containing copper is preferably selected from the group consisting of CaCu ₃ Ti ₄ O ₁₂ , CaCu ₃ Zr ₄ O ₁₂ and CaCu ₃ Hf ₄ O ₁₂ .

The dielectric layer formation is preferably performed using pulse laser deposition.

Preferably, step (b) is:

(i) forming a metal oxide layer by depositing a metal oxide precursor on the lower electrode at a temperature of 20 to 250 ° C. through pulse laser deposition;

(ii) laminating an upper electrode metal layer on the metal oxide layer;

(iii) forming a photosensitive resist pattern on the upper electrode metal layer; And

(iv) patterning the upper electrode metal layer and the metal oxide layer using the photosensitive resist pattern as an etching resist to form a dielectric layer and an upper electrode on a portion of the lower electrode, and removing the photosensitive resist pattern;

It includes.

The thickness of the dielectric layer is preferably 200 nm to 350 nm.

The lower electrode and the upper electrode are preferably made of copper or copper alloy.

According to a preferred embodiment of the present invention, a capacitor-embedded printed circuit board includes:

(a) a base substrate having an inner circuit layer including a lower electrode and a circuit pattern formed on one surface thereof;

(b) a dielectric layer formed of a metal oxide containing copper formed on a portion of the lower electrode;

(c) an upper electrode formed on the dielectric layer;

(d) an insulating resin layer formed on the base substrate such that the lower electrode, the dielectric layer, and the upper electrode are embedded; And

(e) an outer circuit layer formed on the insulating resin layer;

Characterized in that it comprises a.

The capacitor-embedded printed circuit board according to the present invention exhibits high adhesion between the electrode of the capacitor and the dielectric layer, which is excellent in reliability, and excellent dielectric properties can be obtained even by relatively low temperature heat treatment, thereby achieving desired dielectric properties without deformation of the resin substrate. Can be achieved.

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

1 is a cross-sectional view of a capacitor-embedded printed circuit board according to an exemplary embodiment of the present invention.

Referring to FIG. 1, in a base substrate including a resin substrate 11 having an inner circuit layer including a lower electrode 12a and a circuit pattern on one surface and a metal layer 12 on the other surface, the lower electrode 12a On a portion of the dielectric layer 13a made of a metal oxide containing copper and the upper electrode 14a are sequentially formed to provide an embedded capacitor. The built-in capacitor consisting of the lower electrode 12a, the dielectric layer 13a, and the upper electrode 14a is embedded in an insulating resin layer 17 formed on the base substrate, and an outer layer circuit is formed on the insulating resin layer 17. The layer 18 is formed to have a structure in which a capacitor is embedded in the printed circuit board.

The base substrate is not limited to the structure as shown in the drawings, and may be a single-sided printed circuit board, a double-sided printed circuit board, or a multilayer printed circuit board having a plurality of circuit layers and a plurality of insulating layers.

The metal oxide containing copper, preferably, may be selected from the group consisting of CaCu ₃ Ti ₄ O ₁₂ , CaCu ₃ Zr ₄ O ₁₂ and CaCu ₃ Hf ₄ O ₁₂ , the thickness of the dielectric layer composed of the metal oxide Is preferably 200 nm to 350 nm.

On the other hand, the lower electrode and the upper electrode is preferably made of copper or copper alloy, such as a metal material for forming a conventional circuit.

2A to 2I are cross-sectional views illustrating a manufacturing process flow of a capacitor-embedded printed circuit board according to an exemplary embodiment of the present invention. Hereinafter, a method of manufacturing a capacitor-embedded printed circuit board according to the present invention will be described. Explain.

First, in Fig. 2A, a base substrate having an inner circuit layer including one of the lower electrodes 12a and a circuit pattern (not shown) is prepared.

In this drawing, as the base substrate, a double-sided printed circuit having an inner circuit layer including a lower electrode 12a and a circuit pattern (not shown) on one surface of the resin substrate 11 and a metal layer 12 on the other surface thereof. Although the case of the substrate is shown, the present invention is not limited thereto, and a single-sided printed circuit board having no metal layer 12 on the other surface and a multilayer printed circuit board having a plurality of circuit layers and a plurality of insulating layers on the inner layer may also be used. It will be clearly appreciated by those skilled in the art.

The base substrate is preferably formed of an inner circuit layer including the lower electrode 12a and a circuit pattern on one surface of a double-side copper clad laminate through a conventional photolithography method, and at the same time a circuit on the other surface. It can be prepared by forming another circuit layer containing a pattern. Alternatively, it is also possible to form an inner circuit layer comprising the lower electrode 12a and the circuit pattern on only one surface. Accordingly, the metal layer 12 of the other surface may be a circuit pattern of another circuit layer formed through a photolithography method or an unpatterned metal layer, for example, a copper foil layer.

The resin substrate 11 of the base substrate is not particularly limited as long as it is commonly used in the printed circuit board field, and can be used. For example, a thermosetting resin, a thermoplastic resin, a thermosetting resin impregnated with a reinforcing base material, and a reinforcing base material. Any one of the impregnated thermoplastic resins may be used alone or in combination thereof.

The metal for forming a circuit including the metal layer is not particularly limited and can be used as long as it is commonly used in the printed circuit board field. Preferably, copper or copper alloy is used.

Next, in FIG. 2B, a metal oxide layer 13 containing copper is formed on the lower electrode 12a of the base substrate.

Preferably, the metal oxide precursor 13 is deposited on the lower electrode 12a at a temperature of about 20 to 250 ° C. by a pulse laser deposition method to form the metal oxide layer 13.

The metal oxide precursor is not particularly limited as long as it is used as a source of the metal oxide and can form a metal oxide containing copper, which is desired in the present invention at a predetermined temperature.

The copper-containing metal oxide is preferably selected from the group consisting of CaCu ₃ Ti ₄ O ₁₂ , CaCu ₃ Zr ₄ O ₁₂ and CaCu ₃ Hf ₄ O ₁₂ , and depending on the metal oxide, the precursor material may also be appropriately selected. It will be appreciated by those skilled in the art. According to the present invention, by selecting materials containing copper as the metal oxide, it is possible to obtain a high reliability by improving the adhesion between the metal for forming a circuit, in particular copper, to solve the problem of adhesion between the electrode and the dielectric layer. In addition, the metal oxide exhibits excellent dielectric properties such as a desired high dielectric constant in a printed circuit board even by heat treatment at a relatively low temperature, that is, within a range where deformation of the resin substrate does not occur. Free design

On the other hand, the coating of the metal oxide precursor may be carried out without particular limitation through all methods such as chemical vapor deposition, sputtering, pulse laser deposition, etc. known in the art, preferably, it is preferably performed by pulse laser deposition. .

The pulsed laser deposition method is a method of physical vapor deposition for forming a thin film together with sputtering, in which a plasma which shoots a pulsed laser that has a target metal oxide precursor material placed in a vacuum chamber and focuses on a lens faces the target. It is used to crystallize by buried in a high temperature substrate. When the pulsed laser deposition method is used, the complex composition of the desired metal oxide can be easily realized as a thin film without using various precursor materials as a source of the metal oxide. In addition, a thin film can be formed within a relatively short time, and excellent film formation characteristics can be obtained even when a step exists in the deposition site.

Actually applied pulse laser deposition conditions can be appropriately adjusted according to the thickness, area of the desired dielectric layer, and the type of metal oxide precursor actually used. For example, the pulse laser deposition may be performed under an oxygen partial pressure of 10 to 40 mTorr, a repetition period of about 10 Hz, and an energy density of 17 to 37 mJ / mm ² , but is not particularly limited thereto.

In addition, the pulse laser deposition temperature may be appropriately selected depending on the desired dielectric properties of the dielectric layer composed of the metal oxide within a range in which deformation of the resin substrate does not occur, preferably about 20 to 250 ℃.

Next, in FIG. 2C, an upper electrode metal layer 14 is stacked on the metal oxide layer 13. As a metal which comprises the said metal layer, it is as having mentioned above in the said metal for circuit formation, Preferably copper or a copper alloy is used.

Next, in FIG. 2D, after the photosensitive resist 15 is applied onto the upper electrode metal layer 14, the photomask pattern 16 having a predetermined pattern is placed and exposed / developed as shown in FIG. 2E. The photosensitive resist pattern 15a as in 2f is formed.

The photosensitive resist 15 may be used without particular limitation as long as it is known in the art. For example, a dry film or a liquid photosensitive material may be used.

The dry film is composed of three layers of a cover film, a photo-resist film, and a mylarfilm, and a layer substantially acting as a resist is a photoresist film. In the exposure and development process of the dry film, a photo mask pattern, ie, an artwork film on which a predetermined pattern is printed, is brought into close contact with a dry film and irradiated with ultraviolet rays. If not, the unprinted portion may transmit ultraviolet light to cure the dry film under the artwork film. When the dry film is cured, the original film is immersed in the developer, and the uncured dry film portion is removed by the developer, and only the cured dry film portion remains to form an etching resist pattern. As the developer, an aqueous solution of sodium carbonate (Na ₂ CO ₃ ) or potassium carbonate (K ₂ CO ₃ ) may be used.

On the other hand, in the case of using a liquid photosensitive material as a photosensitive resist, a liquid photosensitive material that is exposed to ultraviolet light is dip-coated, roll coated, or electro-deposition on a disc. After coating by a method or the like, it is dried. Next, a predetermined pattern is formed in the photosensitive material by exposing and developing a photosensitive material using the artwork film in which the predetermined pattern was formed. The method using the liquid photosensitive material can be applied thinner than the dry film, there is an advantage that can form a finer circuit pattern. In addition, when the surface of the disc has irregularities, there is also an advantage that can form a uniform surface by filling it.

Next, as shown in FIG. 2G, by etching the photosensitive resist pattern 15a as an etching resist, the upper electrode metal layer and the metal oxide layer of the portion where the photosensitive resist pattern 15a is not applied are patterned. The dielectric layer 13a and the upper electrode 14a are formed on a portion of the lower electrode 12a. After patterning, the photosensitive resist pattern 15a is peeled off and removed.

For example, the etching process may spray and remove an etching solution on a predetermined etching site, thereby etching and removing the upper electrode metal layer and the metal oxide layer except for a portion corresponding to the predetermined pattern to which the etching resist pattern is applied. have.

The thickness of the dielectric layer 13a formed therefrom may be adjusted according to desired dielectric properties, but preferably 200 nm to 350 nm.

Next, in FIG. 2H, the insulating resin layer 17 is pressed and stacked under a predetermined temperature and pressure on the base substrate so that the lower electrode 12a, the dielectric layer 13a, and the upper electrode 14a are embedded.

The insulating resin layer 17 is not particularly limited as long as it is used in the printed circuit board field for interlayer insulation, and any one can be used. For example, an epoxy with glass fiber impregnated as a reinforcing substrate, such as a semi-cured prepreg. Resin and the like can be used.

Next, in FIG. 2I, the capacitor-embedded printed circuit board is completed by forming the outer circuit layer 18 on the insulating resin layer 17 according to a process such as a semi-additive applied in a general printed circuit board field. do.

An example of the process of forming the outer circuit layer 18 will be described in more detail as follows, but it should be noted that the present invention is not particularly limited thereto.

First, via holes are formed in predetermined portions to form electrical connection between the insulating resin layers 17. For example, the via hole may connect the circuit pattern of any one of the outer circuit layers and the lower electrode 12a and the outer circuit and the upper electrode 14a to connect the outer circuit 12 and the lower electrode 12a. Each of the outer circuit layers may be formed between the circuit pattern and the upper electrode 14a.

Here, the process of forming the via hole is preferably a method of forming the via hole according to a preset position using a CNC drill (Computer Numerical Control Drill) or a laser drill.

The CNC drill method is suitable for forming via holes of double-sided printed circuit boards or through holes of multilayer printed circuit boards. After the via hole or the through hole is processed using the CNC drill, it is preferable to perform a deburring process of removing various foreign substances generated during drilling.

The method using a laser is suitable for forming micro via holes of a multilayer printed circuit board. By using such a laser, a YAG laser (Yttrium Aluminum Garnet laser) can be used to simultaneously process a metal layer for forming a circuit and an insulating resin layer, or only an insulating resin layer using a carbon dioxide laser (CO ₂ laser). Can also be processed.

On the other hand, after the via hole is formed, it is preferable to further perform a desmear process to remove smear generated on the sidewall of the via hole by melting the insulating resin layer due to heat generated during the via hole processing.

Next, as described above, the seed layer is formed through electroless metal plating or sputtering on the insulating resin layer on which the via hole is formed.

Subsequently, a plating resist such as the dry film described above is applied onto the seed layer, and a plating resist pattern is formed in a predetermined pattern according to a process such as exposure / development, followed by electrolytic metal plating to form an electrolytic metal plating pattern. .

Finally, the plating resist pattern is peeled and removed, and the seed layer of the portion where the metal plating pattern is not formed is etched away to form a predetermined outer layer circuit layer.

The capacitor-embedded printed circuit board formed as described above may be easily formed with an outer layer, or an outermost layer forming process such as solder resist may be further performed according to a conventional build-up process. It will be recognizable.

As described above, the capacitor-embedded printed circuit board according to the present invention exhibits high adhesion between the electrode of the capacitor and the dielectric layer, which is excellent in reliability, and excellent dielectric properties can be obtained even by relatively low temperature heat treatment, thereby deforming the resin substrate. The desired dielectric properties can be achieved without.

Although the present invention has been described in detail through specific embodiments, this is for describing the present invention in detail, and the capacitor-embedded printed circuit board and the manufacturing method thereof according to the present invention are not limited thereto, within the technical idea of the present invention. It is apparent that modifications and improvements are possible by those skilled in the art.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

1 is a cross-sectional view for explaining a capacitor-embedded printed circuit board according to an exemplary embodiment of the present invention.

2A to 2I are cross-sectional views illustrating a manufacturing process flow of a capacitor-embedded printed circuit board according to an exemplary embodiment of the present invention.

※ Explanation of code about main part of drawing ※

11: resin substrate

12 metal layer 12a lower electrode

13: metal oxide layer 13a: dielectric layer

14 metal layer 14a upper electrode

15 photosensitive resist 15a photosensitive resist pattern

16: photo mask pattern

17: insulation resin layer

18: outer circuit layer

Claims (12)

(a) preparing a base substrate having an inner circuit layer on one surface including a lower electrode and a circuit pattern; (b) forming a dielectric layer comprising a metal oxide containing copper on a portion of the lower electrode, and an upper electrode; (c) laminating an insulating resin layer on the base substrate such that the lower electrode, the dielectric layer and the upper electrode are embedded; And (d) forming an outer circuit layer on the insulating resin layer; Method of manufacturing a capacitor-embedded printed circuit board comprising a. The method according to claim 1, The base substrate is a manufacturing method of a capacitor-embedded printed circuit board, characterized in that the single-sided printed circuit board, double-sided printed circuit board or multilayer printed circuit board. The method according to claim 1, The copper-containing metal oxide is selected from the group consisting of CaCu ₃ Ti ₄ O ₁₂ , CaCu ₃ Zr ₄ O ₁₂ and CaCu ₃ Hf ₄ O ₁₂ The manufacturing method of the capacitor embedded printed circuit board. The method according to claim 1, Forming the dielectric layer is a manufacturing method of a capacitor-embedded printed circuit board, characterized in that is performed using pulse laser deposition (pulse laser deposition). The method according to claim 1, Step (b) is: (i) forming a metal oxide layer by depositing a metal oxide precursor on the lower electrode at a temperature of 20 to 250 ° C. through pulse laser deposition; (ii) laminating an upper electrode metal layer on the metal oxide layer; (iii) forming a photosensitive resist pattern on the upper electrode metal layer; And (iv) patterning the upper electrode metal layer and the metal oxide layer using the photosensitive resist pattern as an etching resist to form a dielectric layer and an upper electrode on a portion of the lower electrode, and removing the photosensitive resist pattern; Method of manufacturing a capacitor-embedded printed circuit board comprising a. The method according to claim 1, The thickness of the dielectric layer is a manufacturing method of a capacitor-embedded printed circuit board, characterized in that 200nm to 350nm. The method according to claim 1, The lower electrode and the upper electrode is a manufacturing method of a capacitor-embedded printed circuit board, characterized in that made of copper or copper alloy. (a) a base substrate having an inner circuit layer including a lower electrode and a circuit pattern formed on one surface thereof; (b) a dielectric layer formed of a metal oxide containing copper formed on a portion of the lower electrode; (c) an upper electrode formed on the dielectric layer; (d) an insulating resin layer formed on the base substrate such that the lower electrode, the dielectric layer, and the upper electrode are embedded; And (e) an outer circuit layer formed on the insulating resin layer; Capacitor embedded printed circuit board comprising a. The method according to claim 8, The base substrate is a printed circuit board with a capacitor, characterized in that the single-sided printed circuit board, double-sided printed circuit board or a multilayer printed circuit board. The method according to claim 8, The copper-containing metal oxide is selected from the group consisting of CaCu ₃ Ti ₄ O ₁₂ , CaCu ₃ Zr ₄ O ₁₂ and CaCu ₃ Hf ₄ O ₁₂ Capacitor embedded printed circuit board. The method according to claim 8, The thickness of the dielectric layer is a capacitor embedded printed circuit board, characterized in that 200nm to 350nm. The method according to claim 8, The lower electrode and the upper electrode is a capacitor embedded printed circuit board, characterized in that made of copper or copper alloy.

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