JP2004039908A - Circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board and its manufacturing method capable of reducing the number of circuit parts and a mounting cost by containing a capacitor in the circuit board, and improving mounting density by miniaturizing and flattening the contained capacitor. <P>SOLUTION: A capacitor structural section 1 comprises a first electrode 2 formed by plating copper and the like, a second electrode 3 formed by processing a second conductive layer located on the second surface of a double-side copper-clad sheet, and a dielectric layer 4 composed of a part of an insulating base 5 interposed between both electrodes 2, 3. The circuit board includes a conductive layer 6 on which required wiring is formed including the lower surface of the first electrode 2. Further, a via hole 7 can be also formed, and instead of a means to form the dielectric layer 4 composed of a part of the insulating base 5, the circuit board can be constituted of a dielectric layer 8 composed of separate electrolytic deposition resin. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit board and a method of manufacturing the same, and more particularly, to a circuit board having a built-in capacitor structure and a method of manufacturing the same.
[0002]
[Conventional technology and its problems]
2. Description of the Related Art In recent years, there has been an increasing demand for downsizing electronic components mounted on electronic devices for small electronic devices such as mobile phones. For example, capacitors are one of the electronic components for mobile phones that are becoming smaller in size. Typical small capacitors for such a mobile phone include 0603 (0.6 × 0.3 × 0.3 mm) and 1005 (1.0 × 0.5 × 0.5 mm).
[0003]
However, it is difficult to reduce the size to the size described below, and the parts cost and the mounting cost are increased because about 250 capacitors are mounted on one mobile phone.
[0004]
In the case of multilayer circuit boards, the method of manufacturing a circuit board having a capacitor by printing a paste-like dielectric is partially adopted, but the interface between the paste and the conductive layer is weak to thermal shock, and the reliability is low. It has been difficult to stably manufacture a circuit board having a capacitor with high cost at low cost.
[0005]
[Means for Solving the Problems]
The present invention, in order to suitably solve the above problems, in the present invention, a concave portion provided at a predetermined location of the insulating substrate, a first electrode provided on the bottom surface and the wall surface of the concave portion, A circuit board having a built-in capacitor structure including a second electrode provided opposite to the first electrode via an insulating base material located on a bottom surface is provided.
[0006]
Further, a hole provided at a predetermined position of the insulating base material, a second electrode provided so as to be exposed at the bottom of the hole, and an insulating material provided at a surface exposed at the bottom of the hole. A circuit incorporating a capacitor structure including a wall surface of the hole and a first electrode provided on the dielectric layer so as to face the second electrode via a dielectric layer separate from the base material. Substrates are also employed.
[0007]
And as a method of manufacturing the circuit board, a double-sided copper-clad board having a first conductive layer on a first surface of an insulating base material and a second conductive layer on a second surface, or Preparing a multilayer circuit board in which the first conductive layer is the outermost conductive layer and the second conductive layer is the inner circuit layer of the multilayer circuit board, and forms an opening at a required position of the first conductive layer. Step of forming a mask layer, the insulating substrate exposed by the opening is subjected to laser processing, plasma etching processing or wet etching processing on the second surface side of the insulating substrate, the thickness of the insulating substrate A step of forming a recess with a part left behind, and a step of plating the bottom and wall surfaces of the recess to form the first electrode can be employed.
[0008]
In addition, the first surface of the insulating substrate has a first conductive layer, the second surface has a second conductive layer on the double-sided copper-clad plate, or the first conductive layer is the outermost layer Preparing a multilayer circuit board that is both a conductive layer and a second conductive layer is an inner circuit layer of the multilayer circuit board, forming an opening at a required position of the first conductive layer to form a mask layer, Laser processing, plasma etching processing or wet etching processing on the insulating base material exposed by the opening, and forming a hole such that the second conductive layer is exposed at the bottom, and forming a hole in the second conductive layer. It is also possible to adopt a method of manufacturing a circuit board including a step of forming a dielectric layer on a surface exposed to the bottom, a step of plating the upper surface of the dielectric, and a wall surface of the hole to form a first electrode.
Further, a single-sided copper-clad board having a conductive layer on one surface of an insulating substrate, or a multilayer circuit board in which the conductive layer on one surface is an inner layer circuit layer of the multilayer circuit board is prepared, Performing laser processing at a required position to form a concave portion on the conductive layer side of the insulating base material while leaving a part of the thickness of the insulating base material, performing plating on the bottom surface and wall surfaces of the concave portion In addition, a method for manufacturing a circuit board having a step of forming a first electrode is also adopted.
[0009]
Then, a single-sided copper-clad board having a conductive layer on one surface of the insulating base material, or a multilayer circuit board in which the conductive layer on one surface is an inner layer circuit layer of the multilayer circuit board is prepared. Performing a laser processing at a required position, forming a hole or a groove so that the conductive layer is exposed at the bottom, forming a dielectric layer on a surface of the conductive layer exposed at the bottom of the hole or the groove, A method of manufacturing a circuit board including a step of forming a first electrode by plating the dielectric upper surface and the wall surface of the hole or groove can also be adopted.
[0010]
Here, in order to form the dielectric layer, a method in which the dielectric layer is formed by electrodeposition of an electrodeposition resin is also adopted.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be further described with reference to the illustrated embodiments. FIG. 1 is a conceptual cross-sectional configuration diagram showing a structure of a circuit board having a built-in capacitor structure of the present invention.
[0012]
This embodiment employs a double-sided flexible board having a built-in capacitor structure manufactured by using a double-sided copper-clad board having a conductive layer such as a copper foil on the first and second surfaces of a flexible insulating base material such as polyimide. 3 shows a flexible circuit board.
[0013]
In FIG. 1, reference numeral 1 denotes a capacitor structure, which is formed by processing a first electrode 2 formed by a plating process of copper or the like and a second conductor layer located on a second surface of a double-sided copper clad plate. It is composed of the formed second electrode 3 and a dielectric layer 4 made of a part of a flexible insulating base material 5 such as polyimide interposed between the two electrodes.
[0014]
Here, reference numeral 6 denotes a first conductor layer subjected to wiring formation processing, and reference numeral 7 denotes a via hole for interlayer connection, which can be manufactured at the same time as the capacitor structure 1 described above.
[0015]
FIG. 2 is a conceptual cross-sectional configuration diagram showing a structure of a circuit board having a built-in capacitor structure according to another embodiment of the present invention.
[0016]
In FIG. 2, reference numeral 1 denotes a capacitor structure which processes a first electrode 2 formed by plating of copper or the like and a second conductor layer of a double-sided copper-clad board having a flexible insulating base material 5. And a dielectric layer 8 made of an electrodeposited resin such as an electrodeposited polyimide between the two electrodes.
[0017]
Here, reference numeral 6 denotes a first conductor layer subjected to wiring formation processing, and reference numeral 7 denotes a via hole for interlayer connection as in FIG. It is possible.
[0018]
FIG. 3 is a manufacturing process diagram of a double-sided flexible circuit board having a built-in capacitor according to an embodiment of the present invention.
[0019]
First, as shown in FIG. 1A, a first surface of an insulating substrate 5 such as a polyimide film has a first conductive layer, and a second surface has a second conductive layer 10. A double-sided copper-clad plate is prepared, and an opening 11 is formed at a required position of the first conductive layer to form a mask layer 12.
[0020]
Here, the unevenness of the copper foil back surface of the double-sided copper-clad board becomes a hindrance factor when accurately forming the capacitance of the capacitor portion, and preferably causes a short circuit when the dielectric is formed thin. In order to prevent this, a copper foil formed on a smooth polyimide film by a technique such as sputtering or electroless plating can be used.
[0021]
Next, as shown in FIG. 2B, laser processing, plasma etching processing, or wet etching processing is performed on a portion of the insulating base material 5 exposed through the opening 11 and located at the via hole forming portion. A part 9 of the thickness of the conductive base material 5 is removed.
[0022]
Next, as shown in FIG. 3C, laser processing, plasma etching processing, or wet etching processing is performed on the via hole forming portion and the capacitor forming portion using the mask layer 12, and the second insulating material 5 is formed. Is formed on the surface side of the insulating substrate 5 while leaving a part of the thickness of the insulating base material 5. At this time, the insulating substrate 5 located in the via-hole forming portion which has been laser-processed in advance has its thickness removed entirely and penetrates to form a hole 14 for forming a via-hole. The insulating substrate 5 located at the portion has about 3 μm remaining at the bottom, which is used as the dielectric layer 4 made of the insulating substrate 5.
[0023]
Therefore, as shown in FIG. 4D, the bottom surface and the wall surface of the hole 14 forming the via hole 7, the bottom surface and the wall surface of the concave portion 13 forming the capacitor forming part 1, and the upper surface of the mask layer 12 are made conductive. Processing and plating are performed to form a plating film 15.
[0024]
Next, as shown in FIG. 5 (5), the plating film 15, the mask layer 12, and the second conductor layer 10 are subjected to wiring forming processing by an etching method, and the double-sided flexible board in which the capacitor structure 1 is built. Obtain a circuit board.
[0025]
As a design example of the capacitor of the above embodiment, when a polyimide film having a thickness of 3 μm and a diameter of 0.2 mm is left on the second conductor layer, the capacitance is about 0.3 pF.
[0026]
By changing the number of capacitors, the thickness of polyimide, and the area, the value of the capacitance on the substrate can be arbitrarily controlled. For example, since the capacitance of a high-frequency small-capacity capacitor used for a mobile phone or the like is about 0.1￣1 pF, the size is 0603 (0.6 × 0.3 × 0.3 mm) or less as in the embodiment. It is possible to manufacture.
[0027]
In addition, since the dielectric breakdown voltage of polyimide is 200 kV / mm in the case of UPILEX manufactured by Ube Industries, Ltd., for example, it becomes 600 V / 3 μm when processed to a thickness of 3 μm, and can be used for various electronic devices. It is.
[0028]
FIG. 4 is a manufacturing process diagram of a double-sided flexible circuit board having a built-in capacitor according to another embodiment of the present invention.
[0029]
First, as shown in FIG. 1A, a first surface of an insulating substrate 5 such as a polyimide film has a first conductive layer, and a second surface has a second conductive layer 10. A double-sided copper-clad plate is prepared, and an opening 11 is formed at a required position of the first conductive layer to form a mask layer 12.
[0030]
Next, as shown in FIG. 2B, the insulating base material 5 exposed through the opening 11 is subjected to laser processing, plasma etching processing or wet etching processing to form a hole 16 for forming a capacitor. Then, a hole 14 for forming a via hole is formed. At this time, the bottoms of these holes may be subjected to removal of the back surface treatment and flattening of the bottom surface by a soft etching method as necessary.
[0031]
Next, as shown in FIG. 3C, a capacitor tape is formed on the bottom surface of the hole 14 for forming a via hole by forming a protective layer using a mask tape so as to prevent electrodeposited polyimide from being electrodeposited. The electrodeposition resin 8 is selectively electrodeposited only on the bottom of the hole 16. Electrodeposited polyimide is suitable as the electrodeposited resin 8. The thickness of the electrodeposited polyimide in this embodiment is about 3 μm.
[0032]
Therefore, as shown in FIG. 4D, the bottom surface and the wall surface of the hole 14 of the via hole 7, the bottom surface and the wall surface of the hole 16 forming the capacitor structure 1, and the upper surface of the mask layer 12 are subjected to a conductive treatment. A plating process is performed to form a plating film 15.
[0033]
Further, as shown in FIG. 5E, the plating film 15 and the mask layer 12 and the second conductor layer 10 are subjected to wiring forming processing including the second electrode 3 by an etching technique, and the capacitor structure 1 is formed. To obtain a double-sided flexible circuit board.
[0034]
Although not shown, it is also possible to obtain a multilayer circuit board having a built-in capacitor by laminating the circuit boards having the built-in capacitors obtained in the above embodiments and applying the laminated circuit board to a multilayer board.
[0035]
FIG. 5 is a manufacturing process diagram of a multilayer circuit board having a built-in capacitor according to still another embodiment of the present invention.
[0036]
First, as shown in FIG. 1A, a single-sided copper-clad board having a first conductive layer on one surface of an insulating base material 5 such as a polyimide film is prepared, and the required thickness of the first conductive layer is determined. An opening is formed at the position to form the mask layer 12.
[0037]
Then, the insulating substrate 5 exposed by the opening is subjected to laser processing, plasma etching processing or wet etching processing to form holes 17 and concave portions 18 for forming capacitors.
[0038]
Next, as shown in FIG. 2B, wiring and electrodes 3 are provided on both surfaces of the insulating substrate 5 at positions corresponding to the concave portions 18 as inner layer circuit boards for the multilayer circuit board. In addition, another hole 17 corresponding to the hole 17 is formed.
[0039]
Next, as shown in FIG. 3C, a single-sided copper-clad plate having a second conductive layer 10 on one surface of an insulating base material 5 such as a polyimide film is prepared, Is formed on the second surface side of the insulating substrate 5 to form a concave portion 19 for forming a capacitor with a part of the thickness of the insulating substrate 5 left.
[0040]
Next, as shown in FIG. 4D, the inner and outer circuit boards shown in FIGS. 1A to 3C are press-bonded by a press, and the bottom surfaces of the concave portions 18 and 19 forming the capacitor structure 1 are formed. Conductivity treatment and plating treatment are performed on the wall surface, and further on the wall surface of the hole 17 and the upper surface of the mask layer 12 to form a plating film 15.
[0041]
Then, as shown in FIG. 5 (5), the plating film 15 and the mask layer 12, and the second conductor layer 10 are subjected to an etching process to form wirings and electrodes 2, 3, thereby obtaining 1, 2 It is possible to obtain a multilayer circuit board incorporating the capacitor structure 1 between the layers and the capacitor structure 1 between the first and third layers.
[0042]
【The invention's effect】
Since the circuit board according to the present invention can incorporate a capacitor in a flexible circuit board or the like, the components and the mounting cost thereof can be reduced with respect to a conventional circuit board, and the mounting density can be improved by miniaturizing and flattening the capacitor. It is possible.
[0043]
In addition, since high reliability of the interface between the dielectric and the conductor, which was difficult to achieve with a circuit board capacitor using a paste-like dielectric, can be ensured, high reliability has been difficult with the conventional manufacturing method. A flexible circuit board or the like having a built-in capacitor can be provided stably at low cost.
[Brief description of the drawings]
FIG. 1 is a conceptual cross-sectional view showing the structure of a circuit board having a built-in capacitor structure according to an embodiment of the present invention.
FIG. 2 is a conceptual cross-sectional view showing the structure of a circuit board having a capacitor structure according to another embodiment of the present invention.
FIG. 3 is a manufacturing process diagram of a double-sided flexible circuit board having a built-in capacitor according to an embodiment of the present invention.
FIG. 4 is a manufacturing process diagram of a double-sided flexible circuit board having a built-in capacitor according to another embodiment of the present invention.
FIG. 5 is a manufacturing process diagram of a multilayer circuit board having a built-in capacitor according to still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Capacitor structure part 2 First electrode 3 Second electrode 4 Dielectric layer 5 made of insulating base material 5 Insulating base material 6 First conductor layer 7 processed by wiring 7 Via hole 8 Dielectric layer made of electrodeposited polyimide

Claims (7)

A concave portion provided at a predetermined portion of the insulating base material, a first electrode provided on the bottom surface and the wall surface of the concave portion, and the first electrode via an insulating base material located on the bottom surface of the concave portion. A circuit board having a built-in capacitor structure comprising a second electrode provided opposite to the first electrode. A hole or a groove provided at a predetermined position of the insulating base material, a second electrode provided to be exposed at the bottom of the hole or the groove, and a second electrode provided at a surface exposed at the bottom of the hole or the groove. In addition, through the dielectric layer separate from the insulating base material, from the first electrode provided on the wall surface of the hole or groove and the dielectric layer so as to face the second electrode. Circuit board with built-in capacitor structure. The first surface of the insulating base material has a first conductive layer, the second surface is a double-sided copper-clad plate having a second conductive layer, or the first conductive layer is the outermost conductive layer Preparing a multilayer circuit board in which the second conductive layer is a layer and an inner circuit layer of the multilayer circuit board, forming an opening in a required position of the first conductive layer to form a mask layer, A step of subjecting the exposed insulating base material to laser processing, plasma etching processing or wet etching processing to form a concave portion on the second surface side of the insulating base material while leaving a part of the thickness of the insulating base material A method of manufacturing a circuit board having a built-in capacitor structure, comprising a step of plating a bottom surface and a wall surface of the concave portion to form a first electrode. The first surface of the insulating base material has a first conductive layer, the second surface is a double-sided copper-clad plate having a second conductive layer, or the first conductive layer is the outermost conductive layer A step of preparing a multilayer circuit board in which the second conductive layer is a layer and an inner circuit layer of the multilayer circuit board, forming an opening in a required position of the first conductive layer to form a mask layer, A step of forming a hole or a groove so that the exposed insulating substrate is subjected to laser processing, plasma etching processing or wet etching processing, and the second conductive layer is exposed at the bottom, or a hole or hole in the second conductive layer. A capacitor structure including a step of forming a dielectric layer on a surface exposed at the bottom of the groove, and a step of plating the upper surface of the dielectric layer and the wall surface of the hole or groove to form a first electrode is incorporated. Manufacturing method of circuit board. Prepare a single-sided copper-clad board having a conductive layer on one surface of an insulating substrate, or a multilayer circuit board in which the conductive layer on one surface is an inner layer circuit layer of the multilayer circuit board, and Performing laser processing on the position, forming a concave portion on the conductive layer side of the insulating base material while leaving a part of the thickness of the insulating base material, plating the bottom surface and the wall surface of the concave portion with a first treatment. A method of manufacturing a circuit board having a built-in capacitor structure having a step of forming electrodes. Prepare a single-sided copper-clad board having a conductive layer on one surface of an insulating substrate, or a multilayer circuit board in which the conductive layer on one surface is an inner layer circuit layer of the multilayer circuit board, and Forming a hole or a groove so that the conductive layer is exposed at the bottom, forming a dielectric layer on a surface of the conductive layer exposed at the bottom of the hole or the groove, A method for manufacturing a circuit board having a built-in capacitor structure, comprising a step of plating a top surface of a layer and a wall surface of the hole or groove to form a first electrode. 7. The method for manufacturing a circuit board according to claim 4, wherein the step of forming the dielectric layer is performed by electrodeposition of an electrodeposition resin.

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