KR101404681B1 - Flexible PCB manufacturing method using high temperature heat treatment and the Flexible PCB thereof - Google Patents

Abstract

The present invention relates to a flexible printed circuit board manufacturing method and a flexible printed circuit board. More particularly, the present invention relates to a method of manufacturing a printed circuit board by transferring a conductive electrode formed through heat treatment at a high temperature to a flexible film. According to the flexible printed circuit board manufactured according to the present invention, it is possible to form the electrode material in the form of metal bulk through the heat treatment at the firing temperature, so that compared with the conventional copper foil etching method, the electric conductivity is the same, And the thin film can be formed, which is advantageous in that the manufacturing cost is low and the application is advantageous even when the thickness restriction condition is difficult such as a mobile phone.

Description

Technical Field [0001] The present invention relates to a flexible printed circuit board manufacturing method and a flexible printed circuit board (PCB)

The present invention relates to a flexible printed circuit board manufacturing method and a flexible printed circuit board, and more particularly, to a flexible printed circuit board having a printed circuit pattern formed on a heat resistant board with a conductive paste, followed by heat treatment at a high temperature to form a conductive electrode, Thereby manufacturing a flexible printed circuit board.

2. Description of the Related Art Generally, a printed circuit board is divided into a rigid circuit board and a flexible printed circuit board. Recently, the use of a flexible printed circuit board, which is light in weight and bendable, has been increasing due to miniaturization and weight reduction of electronic products.

A conventional method for manufacturing a flexible circuit board is a conventional F-PCB method in which a PI (polyimide) film is attached to a thin copper foil to expose a circuit pattern, exposes a portion except for the circuit pattern, have. A conventional F-PCB manufacturing method is a method of forming a conductor by printing a conductive paste on a silk screen or the like as a field of a printing electron due to a complicated processing method and costly and various problems such as environmental pollution through plating .

In the manufacturing method using a printing electron, a paste is prepared by adding an adhesive such as epoxy and acrylic to a silver paste and a paste is prepared by printing it on a film such as polyethylene terephthalate directly using a screen or an inkjet printer, And a method of curing and drying by heat treatment.

In order to fix the flexible printed circuit board to such a flexible printed circuit board, it is necessary to add an epoxy, an acrylic resin and a curing agent which hinders the conductivity, and the conductive silver powder is lower in electrical conductivity than the silver in the bulk state by 10 or more, It is inevitably limited in its use as compared with the manufactured flexible printed circuit board.

The prior art relating to the manufacture of flexible printed circuit boards is disclosed in Korean Patent Publication No. 2012-0010524 (name: a method of manufacturing a multilayer flexible circuit board).

The present invention provides a method of manufacturing a flexible printed circuit board by forming a conductive electrode using a heat resistant substrate at a high temperature of 600 degrees Celsius or more and transferring the conductive electrode onto a film, and a flexible printed circuit board.

In addition, since the present invention can manufacture a metal bulk from a metallic powder by using a heat treatment at a firing temperature, it is possible to form a thin film with the same electric conductivity and a simple process as compared with a conventional copper foil etching method. A flexible printed circuit board manufacturing method and a flexible printed circuit board which are inexpensive and are advantageous even when the thickness restriction condition is difficult such as a mobile phone.

The present invention also relates to a method for manufacturing a flexible printed circuit board which can be used in a wide variety of fields without being limited by application because the conventional conductive curing is remarkably excellent in electric conductivity as compared with a manufacturing method of forming a circuit by printing electrodes, And to provide a flexible printed circuit board.

The present invention relates to a flexible film having a predetermined area and being capable of bending, an adhesive coated on at least a part of one surface of the flexible film, and a conductive paste formed by heat treatment up to a sintering temperature, And a conductive electrode attached to the upper portion of the substrate, wherein the conductive electrode is formed by a high-temperature heat treatment.

In the present invention, on the upper surface of the conductive electrode, a combustion material produced by burning a separating resin in which an inorganic powder, a carbon material, or a carbide is mixed with a resin may be further laminated.

In the present invention, the conductive electrode is formed by heat-treating the conductive paste laminated on the heat-resistant substrate to a firing temperature with a peeling resin formed by mixing an inorganic powder, a carbon material or a carbide in the resin, The conductive electrode is transferred to the flexible film by contacting the conductive electrode formed by heat-treating the conductive paste laminated on the flexible film to the firing temperature, with the flexible film coated with the adhesive.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a circuit pattern of a conductive paste on one surface of a heat-resistant substrate; forming a conductive electrode on the heat-resistant substrate by thermally treating the heat- And a step of transferring the conductive electrode to the flexible film by contacting the flexible film coated with the adhesive to the conductive electrode formed on one surface of the heat resistant substrate.

In the method of manufacturing a flexible printed circuit board according to the present invention, the step of heat-treating the heat-resistant substrate on which the circuit pattern is formed at a firing temperature to form the conductive electrode on the heat- And the conductive electrode is formed by melting at a firing temperature and integrating with each other to form an integral mass.

In the method of manufacturing a flexible printed circuit board according to the present invention, the step of forming a circuit pattern with a conductive paste on one surface of the heat resistant substrate includes the steps of: applying a resin for peeling to the heat resistant substrate; And forming a circuit pattern with the conductive paste on the top of the conductive paste.

In the method of manufacturing a flexible printed circuit board according to the present invention, the peeling resin is formed by mixing an inorganic powder that does not burn at the firing temperature or a carbon material or a carbide, which is burned at the firing temperature, to form a soft material.

In the method of manufacturing a flexible printed circuit board according to the present invention, the inorganic powder of the peeling resin includes a paint, paint, inorganic oxide or mineral containing pigment which is not burned at the firing temperature.

According to the flexible printed circuit board manufacturing method and the flexible printed circuit board according to the present invention, it is possible to manufacture a thin film and a product having excellent electric conductivity, and the manufacturing method is simple, so that the product can be easily manufactured.

In addition, the flexible printed circuit board according to the present invention can be heat treated up to the sintering temperature of the conductive metal, which is different from the electrodes, by the high-temperature heat treatment method, so that the theoretical conductivity of each conductive metal can be realized. It is possible to use not only noble metals such as gold and silver but also copper and nickel, which are non-ferrous metals, as the conductive material.

The flexible printed circuit board according to the present invention is advantageous in that it can apply all printing methods such as screen printing, offset printing, gravure printing, and inkjet printing to a circuit pattern printing method.

1 is a schematic cross-sectional view showing a state in which a resin for peeling and a conductive electrode material are applied to a heat-resistant substrate in a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an embodiment of the present invention,
FIG. 2 is a flowchart sequentially showing the steps of a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an embodiment of the present invention,
FIG. 3 is a process diagram schematically showing a process of a method for manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an embodiment of the present invention,
4 is a cross-sectional view of a flexible printed circuit board fabricated by a method of manufacturing a flexible printed circuit board through heat treatment at a high temperature of a heat-resistant board according to the present invention,
5 is a plan view showing an example of a circuit pattern of a conductive electrode that can be formed in a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to a preferred embodiment of the present invention and a configuration of the flexible printed circuit board will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing a state in which a heat-resistant substrate is coated with a resin for peeling and a conductive paste in a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an embodiment of the present invention, FIG. 3 is a flowchart illustrating a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an exemplary embodiment of the present invention 4 is a cross-sectional view showing a cross-section of a flexible printed circuit board manufactured according to a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to the present invention, FIG. 5 is a cross- 1 is a plan view showing an example of a circuit pattern that can be formed in a method of manufacturing a flexible printed circuit board through a high-temperature heat treatment of a heat-resistant substrate according to an embodiment of the present invention. A.

As shown in FIGS. 1 to 5, the heat-resistant substrate 10 is provided with a flat surface capable of withstanding a heat treatment at a high temperature of 600.degree. C. or more and capable of printing a circuit pattern (S1). As the material of the heat resistant substrate 10, a ceramic substrate including alumina, a substrate of a normal ceramic material, a substrate of a heat-resistant tempered glass, and a metal substrate that can withstand a high temperature heat treatment temperature can be used. Metals having a firing temperature higher than the firing temperature of the conductive metal which is the main component of the paste can be used as the material of the metal substrate. The metal substrate may be formed of non-ferrous metals including stainless steel as well as iron.

A resin 20 for peeling is applied to the upper portion of the heat resistant substrate 10 (S2).

The peeling resin 20 is obtained by uniformly mixing a release material 21 such as an inorganic powder (including minerals and pigments), a carbon material or a carbide with a resin (a natural resin or a synthetic resin). The separating material 21 plays an important role in separating the conductive electrode 31 from the heat resistant substrate 10 in the process of transferring the conductive electrode 31 to the flexible film 40 in the method of manufacturing a flexible printed circuit board according to the present invention And the like.

The resin used for the peeling resin 20 can be any resin which can be applied and is decomposed by heat at a certain temperature or more. For example, thermally decomposable resins including liquid epoxy resin can be used, The thermally decomposable resins which can be used are well known, and a detailed description thereof will be omitted.

The inorganic powder that can be used as the release material 21 contained in the peeling resin 20 may be an oil-based, water-based, enamel paint using a pigment as a vehicle as a vehicle, or a paste-like paint obtained by uniformly mixing a pigment have. The liquid or resin contained in the peeling resin 20 is blown or burned in the process of heating at the firing temperature and the inorganic powder remains as a residue between the conductive electrode 31 and the heat resistant substrate 10, 31 and the heat resistant substrate 10 so as to enable the conductive electrode 31 to be separated from the heat resistant substrate 10 in the process of transferring the conductive electrode 31 to the flexible film 40 . Therefore, the inorganic powder can be formed from a wide variety of inorganic materials (for example, inorganic materials, inorganic oxides, minerals, ceramic powders, etc.) which are burned or not burned at the firing temperature of the electrode material (conductive metal) forming the conductive electrode 31 May be included.

As the release material 21 contained in the peeling resin 20, a carbon material or a carbide may be used in place of the inorganic powder. The carbon material or the carbide is burnt by the high temperature in the heat treatment process to be described later and then burned to leave a residue between the electrode material and the heat resistant substrate to leave a gap between the electrode material and the heat resistant substrate, ) Can be separated from the heat resistant substrate (10). Such carbon materials include, for example, graphite (graphite). Carbides such as calcium carbonate are used. In addition, various carbon materials and carbides that can produce a soft material and enable peeling of a conductive electrode and a heat- have.

Methods for applying the peeling resin 20 may be a low viscosity spraying method, a brushing method, a gravure printing method, an offset printing method, an inkjet printing method, a high viscosity silk screening method, a solid powder coating method, a powder coating method and a laser printer.

A printed circuit pattern 30 is formed on the heat-resistant substrate 10 using a conductive paste containing a conductive electrode material on the resin 20 for peeling (S3). The conductive paste is known to be formed in the form of a paste in order to print a conductive metal powder, which is an electrode material having excellent electrical conductivity, for circuit pattern printing, and thus a detailed description thereof will be omitted. As the electrode material used for the conductive paste, various metal materials including copper and nickel can be used as well as noble metal materials including gold and silver.

As a method of forming the printed circuit pattern 30 with the conductive paste, screen printing, offset printing, gravure printing, inkjet printing, and the like can be used.

The heat-resistant substrate 10 on which the printed circuit pattern 30 is formed with the conductive paste is subjected to heat treatment to the firing temperature of the electrode material of the conductive paste (S4). As described above, a variety of materials can be used for the electrode paste of the conductive paste. Since the firing temperature is different for each electrode material, the heat treatment is performed up to the sintering temperature of the used electrode material. Since the surrounding atmosphere at the time of the firing heat treatment is lost as a conductive conductor when the electrode material is oxidized, it is preferable that the ambient atmosphere during the firing heat treatment is performed in a vacuum or in an inert gas atmosphere in order to prevent oxidation of the electrode material. When the electrode material is a noble metal such as gold, silver, or the like, the ambient atmosphere at the time of sintering heat treatment may be in the air. However, when the electrode material is a nonferrous metal such as copper or nickel, oxidation proceeds at a high temperature to lose its function as a conductive conductor In order to prevent oxidation, the surrounding atmosphere at the time of the firing heat treatment is vacuumed or performed in an inert gas atmosphere.

The powdery electrode material contained in the conductive paste by the heat treatment process up to the firing temperature is melted by the high temperature to be aggregated with each other to form a lump and the moisture and the resin contained in the conductive paste are heat- It is evaporated or burned off. That is, the electrode material powders contained in the conductive paste are melted by the heat treatment process up to the firing temperature, and are merged with each other, whereby the structure is changed into the electrode material mass. The electrical conductivity of the conductive electrode 31 is remarkably improved because the powdery electrode material contained in the conductive paste is changed into a bulk state through the heat treatment from the powder state to the firing temperature.

In addition, the liquid or resin contained in the peeling resin 20 in the heat treatment process (firing process) is evaporated and burned or burned in the process of heating to the firing temperature, so that the conductive electrode 31 and the heat resistant substrate 10 Only the exfoliating material 21 such as an inorganic powder contained in the exfoliating resin 20 or a soft material of a carbon material or a carbide remains. Since the exfoliating material 21 such as an inorganic powder or a soft material of a carbon material or a carbide in the peeling resin 20 is located between the conductive electrode 31 and the heat resistant substrate 10, The adhesion of the substrates 10 to each other is prevented, and as a result, the conductive electrodes 31 can be separated from the heat-resistant substrate 10 in the process of transferring the conductive electrodes. If the peeling resin 20 does not contain an inorganic powder or a peeling material 21 such as a carbon material or a carbide, the electrode material of the conductive paste is fused in the firing process of the heat resistant substrate 10, It is difficult to separate the conductive electrode 31 from the heat resistant substrate 10 and hence the conductive electrode 31 can not be transferred to the flexible film 40. [

When the conductive electrode 31 on the heat-resistant substrate 10 having completed the heat treatment is brought into contact with the soft film 40 coated with the adhesive and the heat-resistant substrate 10 and the soft film 40 are separated from each other, The conductive electrode 31 laminated on the release material 21 is separated from the heat resistant substrate 10 and transferred to the flexible film 40 (S5). Thereby, the flexible printed circuit board on which the conductive electrode 31 is transferred by being transferred to the flexible film 40 is completed.

The method of transferring the conductive electrode 31 on the heat-resistant substrate 10 to the flexible film 40 on which the adhesive is applied is transferred to the printed circuit pattern 30 by simple contact, Various methods such as a roller method or a compression press method can be used.

The flexible film 40 is not limited to a specific material. The PET film used for the present F-PCB as well as the low cost PET film can be used. In addition, all synthetic resin films such as a PS resin for a mobile phone can be used. The flexible film 40 may be a paper material or an arbitrary object. The adhesives applied for the transfer to the flexible film 40 can be adhesives for all purposes including solvent adhesives and water-soluble adhesives, and adhesives for water-based, solid paste and post-tokens can also be used.

The flexible printed circuit board fabricated by the manufacturing method according to the present invention has a printed circuit pattern 30 on which a layer of adhesive (not shown) is placed on the flexible film 40 and a conductive paste is formed on the adhesive layer The conductive electrode 31 is laminated on the upper surface of the conductive electrode 31 by heat treatment up to the firing temperature. The upper surface of the conductive electrode 31 is coated with an inorganic powder formed by heat treatment at the firing temperature, A release material 21 such as a material is formed.

In the preferred embodiment of the present invention, a method for manufacturing a flexible circuit board using a heat resistant substrate at a high temperature of 600 degrees Celsius or more is taken as an example. However, the present invention is applicable to a method for manufacturing a flexible circuit board by heat treating metal powders contained in a conductive paste, The present invention is not necessarily limited to the temperature of 600 DEG C or more, and the heat treatment may be performed in a range of 600 DEG C or less depending on the kind of the conductive electrode material, because the metal powders are melted and then the bulk is formed Of course.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And additions should be considered as falling within the scope of the claims of the present invention.

10 Heat resistant substrate
20 Resin for peeling
21 Release material
30 Printed Circuit Pattern
31 Conductive Electrode
40 Flexible Film

Claims (8)

Applying a releasing resin on the upper surface of a heat-resistant substrate having a flat upper surface capable of printing, the releasing resin including a releasing material which does not disappear at a high temperature of 600 degrees Celsius or more and forms a residue;
Forming a circuit pattern with a conductive paste containing a powder of a conductive metal on the resin for peeling applied to the heat resistant substrate;
Heat-treating the heat-resistant substrate having the circuit pattern formed thereon to a firing temperature of the conductive metal of 600 ° C or more to form a conductive electrode on the heat-resistant substrate; And
And transferring the conductive electrode to the flexible film by contacting the flexible film coated with the adhesive to the conductive electrode of the heat-resistant substrate formed by the heat treatment. The method according to claim 1,
Heat-treating the heat-resistant substrate on which the circuit pattern is formed to a firing temperature of the conductive metal to form the conductive electrode on the heat-resistant substrate
Wherein the conductive electrode is formed by melting the powder of the conductive metal at a sintering temperature of the conductive metal and integrating the powder to form a lump. The method according to claim 1,
Wherein the peeling resin is formed by mixing an inorganic powder that does not burn at the firing temperature of the conductive metal or a carbon material or a carbide that is burned at a firing temperature of the conductive metal to form a soft material, ≪ / RTI > The method of claim 3,
Wherein the inorganic powder comprises a pigment, paint, inorganic oxide or mineral containing pigment which is not burned at the firing temperature of the conductive metal. A method for manufacturing a semiconductor device, which is formed by the manufacturing method according to claim 1,
And the conductive electrode is attached to the upper portion of the flexible film through the adhesive. [5] The flexible printed circuit board according to claim 1, 6. The method of claim 5,
Wherein the conductive electrode is formed on the upper surface of the conductive electrode by further depositing an inorganic powder, a carbon material, or a carbide combustion material on the upper surface of the conductive electrode. 6. The method of claim 5,
Wherein the conductive electrode is formed by heat-treating the conductive paste laminated on the heat-resistant substrate to a firing temperature of the conductive metal with the peeling resin formed by mixing an inorganic powder, a carbon material or a carbide in the resin,
Wherein the conductive electrode is transferred to the flexible film by bringing the conductive electrode formed by heat-treating the conductive paste laminated on the heat-resistant substrate up to the firing temperature of the conductive metal into contact with the flexible film coated with the adhesive. A flexible circuit board on which conductive electrodes are formed by high temperature heat treatment. delete

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