KR100738652B1 - Method for fabricating embedded capacitor - Google Patents

Abstract

The present invention relates to a method of manufacturing an embedded capacitor using a polymer / ceramic composite. More specifically, the polymer / ceramic composite film or paste is used as the dielectric layer of the capacitor, and the thickness variation of the manufactured capacitor is small and the thickness is precise. The present invention relates to a method of manufacturing a built-in capacitor that can be uniformly controlled, and in particular, a spacer can be used to more easily reduce the thickness variation of the capacitor and to more precisely control the thickness of the capacitor.

Embedded Capacitors, Polymer / Ceramic Composite, Spacers, Thickness Deviation

Description

Method for fabricating embedded capacitor

1A to 1D illustrate each process of manufacturing a capacitor by one embodiment of a method of manufacturing an embedded capacitor of the present invention.

{Description of main parts of the drawing}

101: polymer / ceramic composite 102: lower electrode

103: lower substrate 104: upper electrode

105: upper substrate 106: spacer

The present invention relates to a method of forming a capacitor using a polymer / ceramic composite film or paste, and more particularly to a built-in capacitor capable of precise thickness control with low thickness tolerance using a polymer / ceramic composite film or paste. It is about how to.

Recently, electronic products have been developed and improved in a direction that is light and short and improves electrical performance. In this regard, interest in passive devices is increasing. In the case of portable mobile communication devices, passive devices account for a large portion of device components used in electronic products, such as the ratio of passive devices to active devices exceeds 20. This is because the device is much larger than that.

Most of the manual investigations used in electronic products are currently mounted on the surface of the substrate in the form of discrete components. The formation of such passive elements not only occupies a large area of the substrate, but also degrades electrical performance and affects product reliability. It has been known to cause.

Accordingly, internal passive and embedded passive device technology has been developed, which removes existing passive devices from the surface of a substrate and forms and integrates them on one layer of a multilayer structure substrate, thereby reducing the area occupied by passive devices. Chip density of electronic products can be increased, and the connection length between devices is shortened, so that parasitic inductance component is reduced, and electrical performance is also improved.

Among the passive devices, in particular, capacitors occupy more than 40% of passive devices in electronic products and are used as important functions such as decoupling capacitors and bypass capacitors, and thus need to be formed with embedded passive device technology.

One of the materials for forming embedded capacitors, which are capacitors formed with embedded passive device technology, is a polymer / ceramic composite. The polymer / ceramic composite is characterized by both the excellent processability of the polymer and the high dielectric constant of the ceramic. Using this material, it is possible to form a capacitor having a relatively good performance at a low cost at a process temperature of less than 200 degrees Celsius. Can be. In particular, epoxy / ceramic composites have mutual compatibility with plastic printed circuit boards (PCBs) currently used in various ways.

The polymer / ceramic composite is manufactured and used in two forms, a film type or a paste type. In case of the film type, the prepared slurry is manufactured by thin coating on a release paper film or a copper foil, and the paste type is prepared by a method of directly printing or spin coating by preparing a resin having an appropriate viscosity.

By the way, when the capacitor is formed by the above method, there is a problem that the thickness variation occurs by the thick film process. In particular, in the case of forming using a paste type, the printing process is used, so the thickness variation is very large compared with the case of using the film type.

If the thickness variation is large, the capacitance is large for each capacitor formed. Therefore, in order to form a built-in capacitor of equivalent performance, it is necessary to solve the problem of variation in thickness of the material forming the capacitor.

SUMMARY OF THE INVENTION An object of the present invention devised to solve the above problems is to provide a capacitor manufacturing method having precise thickness control and very low thickness variation in forming an embedded capacitor using a polymer / ceramic composite film or paste. To provide.

In order to solve the above problems, the embedded capacitor manufacturing method of the present invention comprises the steps of providing a lower substrate attached to the lower electrode and the upper substrate attached to the upper electrode; Applying a polymer / ceramic composite for embedded capacitor to a surface on which the lower electrode of the lower substrate is attached; Interposing a spacer having a predetermined thickness between the lower substrate and the upper substrate; The surface on which the lower electrode of the lower substrate is attached and the surface on which the upper electrode of the upper substrate is attached face each other with the coated polymer / ceramic composite for embedded capacitor disposed therebetween, so that the upper substrate is bonded to the polymer for the embedded capacitor. / Adhering to the ceramic composite; And applying heat and pressure to flatten and cure the applied polymer / ceramic composite for embedded capacitor to a predetermined thickness formed between the lower substrate and the upper substrate.

In the present invention, the step of interposing the spacer is preferably attached to one selected from the surface on which the lower electrode of the lower substrate is attached or the surface on which the upper electrode of the upper substrate is formed.

In the present invention, the thickness of the spacer is preferably 20 μm (micrometer) or less.

In the present invention, the step of pressing and curing the polymer / ceramic composite for embedded capacitors is preferably to flatten the polymer / ceramic composite for embedded capacitors to a thickness of the spacer.

In the present invention, in the preparing of the lower substrate and the upper substrate, the lower substrate is preferably formed of a printed circuit board.

In the present invention, the preparing of the lower substrate and the upper substrate may be performed by attaching the upper electrode to the upper substrate by one method selected from plating or sputtering.

In the present invention, the applying of the embedded capacitor polymer / ceramic composite may be performed by applying the embedded capacitor polymer / ceramic composite in a form selected from a film or a paste.

In the present invention, after the pressing and curing the polymer / ceramic composite for embedded capacitors, it is preferable to further include separating the upper substrate from the upper electrode.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In adding reference numerals to components of the following drawings, it is determined that the same components have the same reference numerals as much as possible even if displayed on different drawings, and it is determined that they may unnecessarily obscure the subject matter of the present invention. Detailed descriptions of well-known functions and configurations will be omitted.

The present invention applies a polymer / ceramic composite material for embedded capacitors between a bottom electrode and a top electrode, and bonds two substrates, a bottom substrate on which the bottom electrode is formed, and an upper substrate on which the top electrode is formed. And an embedded capacitor having the upper electrode and the lower electrode as two electrodes and using the polymer / ceramic composite material as an internal dielectric.

According to the present invention, a lower substrate having an electrode attached thereto and an upper substrate having an electrode attached thereto are provided, and a polymer / ceramic composite for embedded capacitor is coated on the surface of the lower substrate to which the electrode is attached, between the lower substrate and the upper substrate. Interposing the upper substrate to the polymer / ceramic composite by interposing a spacer for defining a predetermined thickness and facing the electrode attached surface of the lower substrate and the electrode attached surface of the upper substrate to each other; Integrated capacitor by further compressing and curing the applied polymer / ceramic composite by applying heat and pressure to flatten to a predetermined thickness, and then removing only the upper substrate from the electrode attached thereto as necessary. To form.

Figures 1a to 1d shows the state of each process the capacitor is manufactured by an embodiment of the embedded capacitor manufacturing method of the present invention.

FIG. 1A illustrates the lower substrate 103 to which the lower electrode 102 is attached and then the polymer / ceramic composite 101 for embedded capacitor is coated on the lower electrode 102.

The lower substrate 103 is preferably a substrate formed in the form of a printed circuit board (PCB) to form a capacitor.

The lower electrode 102 is attached to one surface of the lower substrate, and the polymer / ceramic composite 101 for an embedded capacitor is coated on the lower electrode of the lower substrate. In the above embodiment, the polymer / ceramic composite is applied in the form of a composite film or paste for embedded capacitors (ECF / ECP), and is applied by a temporary adhesive or dispensing method.

FIG. 1B illustrates that the upper substrate 105 having the upper electrode 104 and the spacer 106 attached thereto is positioned above the lower substrate of FIG. 1A. The upper substrate and the lower substrate are formed of the ECF / ECP 101. It appears to be placed in between.

In particular, FIG. 1B shows a state before the upper substrate is adhered to the polymer / ceramic composite (ECF / ECP) for the embedded capacitor, wherein the spacer 106 is attached to the upper substrate, between the upper substrate and the lower substrate. Already in

In the above embodiment, the upper substrate 105 is provided to face each other with the lower substrate 103 and the ECF / ECP 101 interposed therebetween, and the lower electrode is attached to the surface on which the upper electrode is attached and the lower substrate. Sides are provided to face each other with the ECF / ECP interposed therebetween.

The upper substrate 105 is preferably made of glass, stainless steel, or silicon wafer, and has a high flatness. The upper electrode 104 is attached to the upper substrate by plating or sputtering a metal such as copper. It is desirable to.

FIG. 1C shows the state in which the upper substrate 105 is bonded to the polymer / ceramic composite (ECF / ECP) 101 for an embedded capacitor, and then the ECF / ECP 101 is compressed by applying heat and pressure.

In the above embodiment, the ECF / ECP 101 is bonded to the two substrates between the upper substrate 105 and the lower substrate 103, and pressed and cured by heat and pressure, thereby as shown in FIG. 1A or 1B. Rather than an amorphous form, it is formed flat to a constant thickness between the two substrates of the flat upper substrate and the lower substrate. In particular, the ECF / ECP 101 is pressed under pressure to press the upper substrate 105 in the direction of the lower substrate 103, the thickness of the spacer 106 interposed between the upper substrate and the lower substrate. Squeezed.

The upper electrode and the lower electrode are also adhered to the ECF / ECP by a strong adhesive force, and the upper electrode 104 and the lower electrode 102 are disposed on the upper and lower portions of the flattened ECF / ECP 101 with a dielectric layer interposed therebetween. By positioning the two electrodes of), an embedded capacitor is completed between the upper substrate and the lower substrate. In this case, it is preferable that the upper and lower substrates each include a circuit by a printed circuit board (PCB).

FIG. 1D illustrates a state in which the upper substrate is separated and lifted after the ECF / ECP is pressed and cured in FIG. 1C.

If necessary, instead of leaving the upper substrate in the state of FIG. 1C, the capacitor having the polymer / ceramic composite as the dielectric layer between the two electrodes of the upper electrode and the lower electrode by removing the upper substrate as shown in FIG. An embedded capacitor may be formed by being attached on a substrate. In this case, the lower substrate is preferably formed of a printed circuit board to include a circuit for an embedded capacitor.

In FIG. 1C, the upper electrode is bonded to both the upper substrate and the ECF / ECP. As shown in FIG. 1D, the upper electrode is separated from the substrate and adhered to the ECF / ECP as it is. Therefore, it is necessary to maintain the shape of the capacitor. have. In the preparing of the upper substrate to which the upper electrode is attached, the adhesive force to which the upper electrode is attached to the upper substrate is smaller than the adhesive force acting between the upper electrode and the cured ECF / ECP later, so that the upper substrate can be easily separated and lifted. It is desirable to have.

In the above embodiment, the ECF / ECP 101 is compressed and cured by heat and pressure, and it is necessary to adjust the composition of the ECF / ECP so that no bubbles are formed inside the ECF / ECP which will form the dielectric layer of the embedded capacitor. There is. The polymer / ceramic composite coated in FIGS. 1A and 1B is semi-cured (B-) having some fluidity after a drying step of sufficiently drying the organic solvent through a drying step before pressing and curing under heat and pressure. stage). For solvent-free pastes, fast curing type ECF / ECP, which does not require drying, may be used as the polymer / ceramic composite.

In the above embodiment, the spacer 106 is used to adjust the thickness of the ECF / ECP that is compressed and planarized by heat and pressure by adhesion of the upper substrate and the lower substrate. It is formed to have a predetermined thickness (height) therebetween.

The spacer may be interposed separately on the outside of the ECF / ECP when the upper substrate and the lower substrate is bonded, or may be attached in advance to the surface attached to the upper electrode of the upper substrate or the lower electrode attached to the lower substrate, It may be formed by plating through a pattern or by various methods such as bonding a structure having a predetermined thickness to a substrate or placing it between the substrates.

In any case, the spacer is for precisely controlling the thickness of the ECF / ECP, that is, the thickness of the capacitor dielectric, and the thickness can be adjusted, and the thickness thereof is 20 μm (micrometer) or less, especially around 10 μm. Is preferably.

Since the capacitance of the embedded capacitor formed by the method depends on the thickness of the dielectric layer and the area of the electrode, the capacitance of the capacitor can be adjusted by changing the thickness of the spacer.

By adjusting the thickness of the embedded capacitor through the spacer as described above, it is possible to greatly reduce the thickness variation occurring in the conventional general lamination process. Since a general printed circuit board has a structure in which different materials are stacked, warpage exists in the substrate itself, and the degree of warpage increases as the area of the substrate increases. In the case of a general lamination process without using a spacer, the thickness variation of the dielectric to be compressed increases according to the position of the printed circuit board. In the case of using the spacer as described above, the thickness of the capacitor can be controlled thinly and uniformly. The deviation can be kept small.

In addition, according to the present invention, since the embedded capacitor having the same thickness as that of the spacer is formed and the thickness of the embedded capacitor varies according to the thickness of the spacer, the thickness of the embedded capacitor can be easily and precisely adjusted by adjusting the thickness of the spacer. .

As described above, it has been described with reference to the preferred embodiment of the present invention, but those skilled in the art various modifications and changes of the present invention without departing from the spirit and scope of the present invention described in the claims below I can understand that you can.

As described above, according to the present invention, the thickness variation of the built-in capacitor formed by using the polymer / ceramic composite as a dielectric material can be reduced as compared with the case of the general lamination process, and a capacitor having a more uniform thickness can be formed.

In addition, according to the present invention, the thickness of the embedded capacitor can be easily adjusted by adjusting the thickness of the spacer.

Claims (8)

Preparing a lower substrate having a lower electrode attached thereto and an upper substrate having an upper electrode attached thereto; Applying a polymer / ceramic composite for embedded capacitor to a surface on which the lower electrode of the lower substrate is attached; Interposing a spacer having a predetermined thickness between the lower substrate and the upper substrate; The surface on which the lower electrode of the lower substrate is attached and the surface on which the upper electrode of the upper substrate is attached face each other with the coated polymer / ceramic composite for embedded capacitor disposed therebetween, so that the upper substrate is bonded to the polymer for the embedded capacitor. / Adhering to the ceramic composite; And Applying heat and pressure to uniformly compress and cure the applied polymer / ceramic composite for embedded capacitor to a predetermined thickness formed between the lower substrate and the upper substrate. The method of claim 1, wherein the interposing of the spacer is attached to one of the spacers attached to the lower electrode of the lower substrate or the surface on which the upper electrode of the upper substrate is formed. . The method of claim 1, wherein the spacer has a thickness of 20 micrometers or less. The method of claim 1, wherein the squeezing and curing of the polymer / ceramic composite for embedded capacitors comprises pressing the polymer / ceramic composite for embedded capacitors flat to a thickness of the spacer. The method of claim 1, wherein the preparing of the lower substrate and the upper substrate comprises forming the lower substrate as a printed circuit board. The method of claim 1, wherein the preparing of the lower substrate and the upper substrate is performed by attaching the upper electrode to the upper substrate by one method selected from plating or sputtering. The method of claim 1, wherein the applying of the polymer / ceramic composite for embedded capacitors comprises applying the polymer / ceramic composite for embedded capacitors in a form selected from a film or a paste. The method of claim 1, further comprising: separating and removing the upper substrate from the upper electrode after pressing and curing the polymer / ceramic composite for embedded capacitor.

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