KR101915947B1 - Flexible printed circuit boards and method for fabricating the same - Google Patents

Abstract

A flexible circuit board and a method of manufacturing the same are provided. The flexible circuit board includes a base film, a plurality of first conductive patterns formed on one surface of the base film, a first protection layer formed to cover the plurality of first conductive patterns, and a first heat radiation layer The first heat dissipation layer includes a base material and a heat dissipation material contained in the base material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a flexible circuit board,

The present invention relates to a flexible circuit board and a manufacturing method thereof.

BACKGROUND ART [0002] In recent years, a chip on film (COF) package technology using a flexible circuit board has been used in electronic devices in accordance with the miniaturization trend. The flexible circuit board and the COF package technology using the flexible circuit board are used for a flat panel display (FPD) such as a liquid crystal display (LCD), an organic light emitting diode do.

The conductive pattern formed on the flexible circuit board connects the circuit elements and transmits an electrical signal transmitted at a high speed. On the other hand, with the miniaturization of electronic devices in which a flexible circuit board is mounted, integration of a flexible circuit board and a conductive pattern formed thereon is progressively increasing. However, problems in operation of the circuit element due to heat generated on the conductive pattern have.

A method of increasing the thickness of the conductive pattern or attaching a metal tape made of aluminum or copper to the back surface of the base film on which the conductive pattern is formed has been introduced in order to effectively dissipate the heat generated from the conductive pattern. However, such a method may make miniaturization of the flexible circuit board difficult, or may require additional processing, which may cause problems such as an increase in production cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flexible circuit board having a heat radiation property including a heat radiation layer containing a heat radiation material on a protective layer covering a conductive pattern.

The present invention provides a method of manufacturing a flexible circuit board on which a heat radiation layer containing a heat radiation material is formed on a protective layer covering other technical conductive patterns to be solved by the present invention.

The technical objects of the present invention are not limited to the technical matters mentioned above, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided a flexible printed circuit board including a base film, a plurality of first conductive patterns formed on one surface of the base film, 1 protective layer and the first protective layer, wherein the first heat dissipation layer includes a base material and a heat dissipation material contained in the base material.

In some embodiments of the present invention, the height of the top surface of the first protective layer from the base film may be equal to or higher than the height of the top surface of the plurality of conductive patterns from the base film.

In some embodiments of the present invention, the top surface of the first heat dissipation layer may be substantially flat.

In some embodiments of the present invention, the ratio of the thickness of the first protective layer to the thickness of the first heat dissipation layer may be from 2: 8 to 8: 2.

In some embodiments of the present invention, the thickness of the first protective layer is 1 to 30 탆, the thickness of the first heat dissipation layer is 1 to 30 탆, the thickness of the first protective layer and the first heat dissipation layer May be from 2 탆 to 60 탆.

In some embodiments of the present invention, the base material may comprise the same material as the material constituting the first protective layer.

In some embodiments of the present invention, a plurality of second conductive patterns formed on the other surface opposite to the one surface of the base film, a second protective layer formed to cover the plurality of second conductive patterns, and a second protective layer covering the second protective layer And a second heat dissipation layer including a heat dissipation material therein.

In some embodiments of the present invention, the first passivation layer is formed along the profile of the plurality of first conductive patterns, the top surface of the first passivation layer has a first surface on the first conductive pattern, And a height of the first surface from the base film may be higher than a height of the second surface from the base film.

In some embodiments of the present invention, the first heat dissipation layer may be formed along the profile of the upper surface of the first passivation layer.

In some embodiments of the present invention, a plating layer interposed between the first conductive pattern and the first protective layer may be further included.

According to another aspect of the present invention, there is provided a method of manufacturing a flexible circuit board, including: providing a base film having a plurality of conductive patterns formed on at least one surface thereof; forming a protective layer to cover the plurality of conductive patterns; And forming a heat-radiating layer including a heat-radiating material mixed therein, on the protective layer.

In some embodiments of the present invention, forming the heat dissipation layer may include forming the heat dissipation layer from the base film higher than the top surface of the conductive pattern.

According to the flexible circuit board according to the embodiments of the present invention, a heat radiation layer including a heat radiation material is formed on the base film, so that heat generated from the conductive pattern can be effectively emitted.

Further, the protective layer interposed between the heat radiation layer and the conductive pattern is formed so as to completely cover the conductive pattern, so that the electrical reliability of the heat radiation material contained in the heat radiation layer can be prevented from deteriorating.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a cross-sectional view of a flexible circuit board according to an embodiment of the present invention.
Fig. 2 is an enlarged view of a part of Fig. 1 enlarged.
3 is a cross-sectional view of a flexible circuit board according to another embodiment of the present invention.
4 is a cross-sectional view of a flexible circuit board according to another embodiment of the present invention.
5 is a flowchart illustrating a method of manufacturing a flexible circuit board according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. The dimensions and relative sizes of the components shown in the figures may be exaggerated for clarity of description. Like reference numerals refer to like elements throughout the specification and "and / or" include each and every combination of one or more of the mentioned items.

It is to be understood that when an element or layer is referred to as being "on" or " on "of another element or layer, All included. On the other hand, a device being referred to as "directly on" or "directly above " indicates that no other device or layer is interposed in between.

The terms spatially relative, "below", "beneath", "lower", "above", "upper" May be used to readily describe a device or a relationship of components to other devices or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions. The elements can also be oriented in different directions, so that spatially relative terms can be interpreted according to orientation.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms " comprises "and / or" comprising "used in the specification do not exclude the presence or addition of one or more other elements in addition to the stated element.

Although the first, second, etc. are used to describe various elements or components, it is needless to say that these elements or components are not limited by these terms. These terms are used only to distinguish one element or component from another. Therefore, it is needless to say that the first element or the constituent element mentioned below may be the second element or constituent element within the technical spirit of the present invention.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

FIG. 1 is a cross-sectional view of a flexible circuit board according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a portion of FIG.

1 and 2, a flexible circuit board according to an embodiment of the present invention includes a base film 10, a first conductive pattern 20, a first protective layer 30, a first heat dissipation layer 40, . ≪ / RTI >

The base film 10 may be formed of a flexible material and may be included as a base material on the flexible circuit board 1 so that the flexible circuit board 1 may be bent or folded. The base film 10 may be, for example, a polyimide film. Alternatively, the base film 10 may be a PET film, a polyethylene naphthalate film, a polycarbonate film, or an insulating metal foil. In the electronic device 1 according to the embodiment of the present invention, the base film 10 is described as a polyimide film.

The first conductive pattern 20 may be formed on the base film 10. For example, the first conductive pattern 110 may have at least one conductive line having a predetermined width. The first conductive pattern 20 can transmit an electrical signal between circuit devices mounted on the base film 10 and electronic devices to which the flexible circuit board 1 is connected.

The first conductive pattern 20 may comprise, for example, a conductive material such as copper, but the present invention is not limited thereto. Specifically, the first conductive pattern 20 may be made of an electrically conductive material such as gold, aluminum, or the like.

The first protective layer 30 may be formed to cover the first conductive pattern 20. The first passivation layer 30 may include an insulating material, and the insulating material may be, for example, a solder resist. Or the first protective layer 30 may include a coverlay film.

The first protective layer 30 may completely cover the first conductive pattern 20. That is, the level of the upper surface 35 of the first protective layer 30 may be equal to or higher than the level of the uppermost surface 25 of the first conductive pattern 20. The height of the top surface 35 of the first protective layer 30 from the base film 10 may be equal to or greater than the height of the top surface 25 of the first conductive pattern 20 from the base film 10.

An additional plating layer may be formed between the first conductive pattern 20 and the first protective layer 30 so as to cover the surface of the first conductive pattern 20 although not shown in FIG. Such a plating layer can be formed, for example, by plating a material such as copper, tin, nickel, palladium, gold, or the like on the first conductive pattern 20.

In the flexible circuit board 1 according to the embodiment of the present invention, the upper surface 35 of the first protective layer 30 may be substantially flat. Here, the substantially flat surface may include a case where a slight unevenness is formed on the upper surface of the first protective layer 30. However, in spite of such unevenness, the height difference between the uppermost portion and the lowermost portion of the upper surface of the first protective layer 30 is extremely small, which is negligible as compared with the total thickness of the first protective layer 30.

The first passivation layer 30 is formed on the first conductive pattern 20 to form the first passivation layer 30 having a flat upper surface and then the first passivation layer 30 is formed on the first passivation layer 30, A step of planarizing the upper surface of the semiconductor substrate 100 may be added.

On the first passivation layer 30, a first heat dissipation layer 40 may be formed. The first heat-dissipating layer 40 may be formed to cover the upper surface of the first passivation layer 30. 1, the first heat dissipation layer 40 may be formed to completely cover the surface of the first passivation layer 30, but the present invention is not limited thereto. The first heat dissipation layer 40 may be formed to cover only the region on the first passivation layer 30 overlapping the first conductive pattern 20.

The height of the upper surface 35 of the first protective layer 30 may be equal to or higher than the height of the uppermost surface 25 of the first conductive pattern 20, The height of the lower surface 41 of the first heat dissipation layer 40 may be equal to or higher than the height of the uppermost surface 25 of the first conductive pattern 20.

In some embodiments of the present invention, the ratio of the thickness of the first passivation layer 30 to the thickness of the first heat dissipation layer 40 may be from 2: 8 to 8: 2. The thickness of the first protective layer 30 refers to the height from the upper surface of the first conductive pattern 20 to the upper surface 35 of the first protective layer 30. The thickness of the first heat- Refers to the height from the lower surface 41 of the first heat dissipation layer 40 on the upper surface 35 of the first protective layer 30 to the uppermost surface of the first heat dissipation layer 40. If the thickness of the first heat dissipation layer 40 is too thin compared to the thickness of the first protection layer 30, the heat dissipation effect of the first conductive pattern 20 by the first heat dissipation layer 40 may be insufficient have. On the other hand, when the thickness of the first passivation layer 30 is too thin as compared to the first heat dissipation layer 40, there is a fear that the insulation property is lowered. In contrast, when the thickness of the first passivation layer 30 is less than the thickness of the first passivation layer 30, The manufacturing cost of the flexible circuit board 1 may be excessively increased as compared with the increase in the heat radiation effect.

In some embodiments of the present invention, the thickness of the first passivation layer 30 may be 1 to 30 占 퐉, the thickness of the first heat dissipation layer 40 may be 1 to 30 占 퐉, and the thickness of the first passivation layer 30 And the thickness of the first heat-radiating layer 40 may be 2 占 퐉 to 60 占 퐉.

The first heat-radiating layer 40 may include a base material and a heat-radiating member 45. The base material may comprise, for example, a solder resist or a coverlay film. In some embodiments of the present invention, the base material of the first heat-dissipating layer 40 may comprise the same material as the first passivation layer 30.

The heat dissipating member 45 as the heat dissipating member included in the first heat dissipating layer 40 may include a material having a high thermal conductivity and may be formed of a metallic material such as aluminum or copper or a carbon material such as graphene or carbon nanotubes , Or may contain compounds thereof.

In some embodiments of the present invention, the heat radiating member 45 may include a spherical heat radiating ball, but the present invention is not limited thereto. The heat dissipating member 45 may have a polyhedron shape such as a hexahedron or the like and may be formed of any material that can mix heat with the base material of the first heat dissipation layer 40 and transmit heat generated in the first conductive pattern 20 to air, And can be applied to the invention.

The heat generated from the first conductive pattern 20 is discharged to the outside by the heat dissipating member 45 included in the first heat dissipating layer 40 in the flexible circuit board 1 according to the embodiment of the present invention . The circuit elements and the electronic device mounted on the first conductive pattern 20 by the first heat radiation layer 40 reduce the influence of the heat received from the heat generated in the first conductive pattern 20, Can be increased.

The formation of the first heat-radiating layer 40 on the first protective layer 30 is advantageous in terms of the production process and production cost as compared with the case where a separate metal tape is formed on the back surface of the base film 10 .

In the flexible circuit board 1 according to an embodiment of the present invention, the first heat dissipation layer 40 may be spaced apart from the first conductive pattern 20 due to the first passivation layer 30. Since the height of the upper surface 35 of the first protection layer 30 is equal to or higher than the height of the uppermost surface of the first conductive pattern 25, The heat radiation material 45 included in the layer 40 and the first heat radiation layer 40 is not located.

When the first heat dissipation layer 40 containing the heat dissipation member 45 is interposed between the first conductive patterns 20 on the base film 10 and the heat dissipation member 45 reacts with moisture or the like, The insulation effect between the plurality of first conductive patterns 20 can be reduced due to the leakage current formed so as to flow between the patterns 20. Therefore, the operational reliability of the flexible circuit board 1 may also be deteriorated.

However, the first heat-radiating layer 40 of the flexible circuit board 1 according to an embodiment of the present invention may include a first heat-radiating layer 40 and a first heat- A leakage current is generated between the first conductive patterns 20 even when the heat dissipating member 45 in the first heat dissipating layer 40 reacts with moisture because the heat dissipating member 45 included in the first conductive patterns 40 is not located. And effectively isolate the first conductive patterns 20 from each other.

3 is a cross-sectional view of a flexible circuit board according to another embodiment of the present invention. Hereinafter, a description of common parts with the above-described embodiments will be omitted and differences will be mainly described.

Referring to FIG. 3, the flexible circuit board 2 according to another embodiment of the present invention includes the flexible circuit board, the first passivation layer 130, and the first heat dissipation layer 140 in the above- .

The top surface 135 of the first passivation layer 130 may be formed along the profile of the top surface of the first conductive pattern 20. That is, the upper surface 135 of the first passivation layer 130 includes a first surface 136 on the first conductive pattern 20 and a second surface 137 between the first surface 136, The height of the first surface 136 from the film 10 is higher than the height of the second surface 137.

Although the top surface 135 of the first protective layer 130 is formed along the profile of the top surface of the first conductive pattern 20, the top surface 135 of the first protective layer 130 may still be equal to or higher than the height of the top surface of the first conductive pattern 20 have. That is, the level of the second surface 137 lower than the height of the first surface 136 of the upper surface 135 of the first protective layer 130 is still equal to or higher than the level of the uppermost surface of the first conductive pattern 20 It is possible to prevent the heat dissipation member included in the first heat dissipation layer 140 and the first heat dissipation layer 40 from being located between the first conductive patterns 20 between the first conductive patterns 20. [ The insulation effect between the first conductive pattern 20 due to the first protective layer 130 and the first heat dissipation layer 140 can be maintained as it is in spite of the shape of the top surface 135 of the deformed first protective layer 130 Can be maintained.

The first protective layer 130 is formed along the profile of the upper surface of the first conductive pattern 20 so that the shape of the first heat dissipation layer 140 covering the first protective layer 130 is also the same as that of the first protective layer 130 ). ≪ / RTI > The upper surface of the first heat dissipation layer 140 may include a first surface 141 on the first conductive pattern 20 and a second surface 142 between the first surface and the first surface 141, May be higher than the height of the second surface 142.

The height of the lower surface of the first heat dissipation layer 140 may be equal to or higher than the height of the uppermost surface of the first conductive pattern 20, as in the above-described embodiments.

Since the first protective layer 130 has a profile of the surface of the first conductive pattern 20 in the flexible circuit board 2 according to the present embodiment, the upper surface 135 of the curved first protective layer 130 The surface area of the upper surface 135 of the first protective layer 130 can be increased. Also, the contact area between the first passivation layer 130 and the first heat dissipation layer 140 can be increased by the surface area of the upper surface 135 of the first passivation layer 130. Accordingly, the heat transfer efficiency of the first conductive pattern 20 transferred to the first heat dissipation layer 140 through the first passivation layer 130 can be increased.

When the first passivation layer 130 is formed along the profile of the first conductive pattern 20, the first passivation layer 130 is formed and then the upper surface of the first passivation layer 130 is planarized May not be performed.

4 is a cross-sectional view of a flexible circuit board according to another embodiment of the present invention.

4, a flexible circuit board 3 according to another embodiment of the present invention includes a second conductive pattern 120 formed on the opposite side of the first conductive pattern 20 of the base film 10, The second passivation layer 240 and the vias 51 penetrating through the base film 10 may be further included.

The second conductive pattern 120 may be formed on the opposite surface of the base film 10 on which the first conductive pattern 20 is formed. The second conductive pattern 120 may include at least one conductive line having a predetermined width in the same manner as the first conductive pattern 20.

The second conductive pattern 120 may be electrically connected to the first conductive pattern 20 through a via 51 penetrating the substrate. The via 51 may fill the via hole 50 formed through the base film 10. Like the first and second conductive patterns 120, the vias 51 may include a conductive material such as copper or gold or an alloy thereof. Although not shown in FIG. 4, may include at least one additional metal layer between the inner wall of the via hole 50 and the via 51.

4 illustrates that the first conductive pattern 20 and the second conductive pattern 120 are formed at positions corresponding to the base film 10, but the present invention is not limited thereto. It will be apparent to those of ordinary skill in the art that the arrangement of the first and second conductive patterns 20 may vary depending on the design of the flexible circuit board 1 and the arrangement of the circuit elements mounted thereon .

A second passivation layer 230 may be formed to cover the second conductive pattern 120. The second protective layer 230 may be formed to completely cover the second conductive pattern 120, like the first protective layer 30. Therefore, the height of the upper surface of the second protective layer 230 from the other surface of the base film 10 may be equal to or higher than the height of the uppermost surface of the second conductive pattern 120.

The second heat dissipation layer 240 may be formed on the second passivation layer 230. The second heat-radiating layer 240 may include a base material which is an insulating material and a heat-radiating material contained in the base material. The first heat-dissipating layer 40 and the second heat-dissipating layer 240 may include the same material. That is, the base material and the heat dissipation layer constituting the first heat dissipation layer 40 and the second heat dissipation layer 240 may include the same material.

4, the second heat dissipation layer 240 may be formed to completely cover the second passivation layer 230. Alternatively, the second heat dissipation layer 240 may be formed to cover the second passivation layer 230, But may be formed to cover only the upper surface of the second protective layer 230 on the formed region.

The upper surface of the second passivation layer 230 is formed to be equal to or higher than the level of the upper surface of the second conductive pattern 120 so that the second heat dissipation layer 240 is not interposed between the second conductive patterns 120 Is the same as the description related to the first heat-radiating layer (40). Accordingly, the shape of the second heat-dissipation layer 240 helps release the heat generated in the second conductive pattern 120 into the air, and at the same time, a leakage current is generated between the second conductive pattern 120 and the heat- It is possible to prevent the operation reliability of the substrate 3 from being reduced.

5 is a flowchart illustrating a method of manufacturing a flexible circuit board according to an embodiment of the present invention.

Referring to FIG. 5 and FIG. 1, a method of manufacturing a flexible circuit board according to an embodiment of the present invention includes providing a base film having a plurality of conductive patterns formed on at least one surface thereof (S10) A first protective layer is formed so as to cover the first passivation layer, and a heat dissipation layer is formed on the first passivation layer (S30).

The first conductive pattern 20 may be formed, for example, by a semi-additive process that forms a resist on the base film 10 and performs plating in an electrolytic or non-electrolytic manner, An etching process of forming a conductive layer on the conductive layer 10 and etching the conductive layer.

The formation of the first passivation layer 30 to cover the plurality of first conductive patterns 20 may include forming a solder resist or a coverlay film on the first conductive pattern 20 by printing or laminating . The first protective layer 30 needs to be formed sufficiently so that the level of the upper surface of the first protective layer 30 can be higher than the level of the uppermost surface of the first conductive pattern 20.

Here, in order to maintain the level of the upper surface of the first passivation layer 30 substantially flat, a step of planarizing the upper surface after the first passivation layer 30 is formed may be added. The planarization of the upper surface of the first protective layer 30 may include, for example, pressing the upper surface of the first protective layer 30 with a press.

The formation of the first radiation layer 40 to cover the first protection layer 30 is achieved by printing or laminating a solder resist or coverlay film containing the radiation material 45 on the first protection layer 30 As shown in FIG.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1, 2, 3: Flexible circuit board 10: Base film
20, 120: conductive pattern 30, 130, 230: protective layer
40, 140: heat dissipating layer 45: heat dissipating material

Claims (12)

A base film;
A plurality of first conductive patterns formed on one surface of the base film;
A first protective layer formed to cover the plurality of first conductive patterns; And
Wherein the heat dissipation layer includes a first heat dissipation layer including a base material and a heat dissipation material contained in the base material,
The height of the top of the top surface of the first protective layer from the base film is equal to or higher than the height of the top surface of the plurality of conductive patterns from the base film,
Wherein the first passivation layer and the first heat dissipation layer are formed along the profile of the plurality of first conductive patterns. delete delete The method according to claim 1,
Wherein a ratio of a thickness of the first passivation layer to a thickness of the first heat dissipation layer is 2: 8 to 8: 2. The method according to claim 1,
The thickness of the first protective layer is 1 탆 to 30 탆,
The thickness of the first heat dissipation layer is 1 to 30 탆,
Wherein the sum of the thicknesses of the first protective layer and the first heat dissipation layer is 2 占 퐉 to 60 占 퐉. The method according to claim 1,
Wherein the base material comprises the same material as the material constituting the first protective layer. The method according to claim 1,
A plurality of second conductive patterns formed on the other surface opposite to the one surface of the base film;
A second protective layer formed to cover the plurality of second conductive patterns; And
And a second heat dissipation layer covering the second protection layer and including a heat dissipation material therein. The method according to claim 1,
Wherein an upper surface of the first protective layer includes a first surface on the first conductive pattern and a second surface between the first surface,
Wherein a height of the first surface from the base film is higher than a height of the second surface from the base film. delete The method according to claim 1,
And a plating layer interposed between the first conductive pattern and the first protective layer. Providing a base film on which a plurality of conductive patterns are formed on at least one surface,
A protective layer is formed to cover a plurality of conductive patterns,
And forming a heat dissipation layer including a heat dissipation material mixed therein, on the protective layer,
Wherein a height of an uppermost portion of an upper surface of the protective layer from the base film is higher than a height of an uppermost surface of the plurality of conductive patterns from the base film,
Wherein the protective layer and the heat dissipation layer are formed along the profile of the plurality of conductive patterns. 12. The method of claim 11,
Wherein forming the heat dissipation layer includes forming the heat dissipation layer from the base film to be higher than the uppermost surface of the conductive pattern.

Images