KR102461189B1 - Flexible copper clad laminate, printed circuit board using the same - Google Patents

Abstract

Flexible copper-clad laminate according to an embodiment of the present invention, a resin layer; a tie coat layer formed on the resin layer; and a copper layer formed on the tie coat layer, wherein binding ratios of C-C, C-N, C-O and C=O appearing on the surface of the tie coat layer upon peeling between the resin layer and the tie coat layer. ) are 40at% or more, 25at% or more, 7at% or more, and 10at% or more, respectively.

Description

Flexible copper clad laminate and printed circuit board using the same

The present invention relates to a flexible copper clad laminate (FCCL) and a printed circuit board using the same, and more particularly, to a flexible copper clad laminate having superior high-temperature peel strength characteristics compared to a conventional flexible copper clad laminate, and a printed circuit board using the same.

A printed circuit board (PCB) is an electrical wiring for connecting various parts expressed in a wiring diagram according to a circuit design, and serves to connect or support various parts. In particular, the demand for printed circuit boards has increased with the development of electronic devices such as notebook computers, mobile phones, PDAs, small video cameras, and electronic notebooks. Furthermore, the electronic devices are increasingly smaller and lighter as portability is emphasized. Accordingly, printed circuit boards are becoming more integrated, smaller, and lighter.

According to the physical properties of the printed circuit board, a rigid printed circuit board, a flexible printed circuit board, a rigid-flexible printed circuit board combining the two, and a rigid-flexible printed circuit board similar to a multi-flexible divided into printed circuit boards. In particular, flexible copper clad laminate (FCCL), a raw material for flexible printed circuit boards, is used in digital home appliances such as mobile phones, digital camcorders, notebook computers, and LCD monitors. is increasing rapidly.

A flexible copper-clad laminate is a laminate of a polymer film layer and a metal conductive layer, and is characterized by flexibility. Flexible copper clad laminates are used in electronic devices or material parts of electronic devices that require particularly flexibility or flexibility, contributing to miniaturization and weight reduction of electronic devices.

Conventional flexible copper-clad laminates related to this technology are largely divided into a method of applying a polyimide-based resin to a copper foil and a method of depositing copper on a polymer film. In particular, the copper deposition method can form a very thin copper film.

The deposition-type flexible copper-clad laminate is manufactured by forming a tiecoat layer on a polymer film by sputtering, and then passing it through a copper electrolytic plating bath continuously while electrolytically plating copper.

The fabricated flexible copper clad laminate is used after a circuit is formed and a semiconductor chip or electric device is mounted on the circuit, and the miniaturization, multi-pin, and narrow pitch of driver ICs are rapidly progressing. Accordingly, there is a demand for a flexible copper-clad laminate having excellent physical properties such as etching properties, peel strength, and thin film density characteristics.

Regarding peel strength among the physical properties of the copper clad laminate, there have been many efforts to improve the high temperature peel strength characteristics, but it is still not possible to obtain a sufficiently satisfactory high temperature peel strength.

The present invention was devised in consideration of the above problems, and an object of the present invention is to provide a technique capable of remarkably improving the high-temperature peel strength between the resin layer and the tie coat layer.

However, the technical problems to be achieved by the present invention are not limited to the above-described problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the description of the invention described below.

The present inventors have continued research to develop a technique capable of improving the high-temperature peel strength between the resin layer and the tie coat layer. As a result, the present inventors control that the C-C, C-N, C-O, C=O binding ratio appearing on the surface of the metal layer after peeling between the resin layer and the metal layer is at a certain level or more, and also the metal layer after peeling By controlling the roughness appearing on the surface to be within a certain range, a flexible copper-clad laminate that satisfies the required strength has been manufactured.

A flexible copper-clad laminate according to an embodiment of the present invention developed according to such research includes a resin layer; a tie coat layer formed on the resin layer; and a copper layer formed on the tie coat layer, wherein binding ratios of C-C, C-N, C-O and C=O appearing on the surface of the tie coat layer upon peeling between the resin layer and the tie coat layer. ) is 40at% or more, 25at% or more, 7at% or more, and 10at% or more, respectively.

The resin layer may be formed of a polyimide (PI) resin.

The resin layer may have a binding ratio of C-C, C-N, C-O and C=O appearing on the surface of 75at% or more, 20at% or more, 5at% or more, and 10at% or more, respectively.

The tie-coat layer may have a roughness appearing on the surface after the peeling of 12 nm to 19 nm.

The tie coat layer may be formed of an alloy containing Ni, Mo and Nb.

The tie coat layer may be formed to a thickness of 5 nm to 35 nm.

The copper layer may include a copper seed layer formed on the tie coat layer; and a copper film layer formed on the copper seed layer.

The copper seed layer may be formed to a thickness of 10 nm to 100 nm.

The copper film layer may be formed to a thickness of 5 μm to 15 μm.

Meanwhile, a printed circuit board according to an embodiment of the present invention includes a wiring pattern formed on a copper layer of the flexible copper clad laminate according to an embodiment of the present invention.

A method of manufacturing a flexible copper-clad laminate according to an embodiment of the present invention comprises the steps of: (a) preparing a polymer film constituting a resin layer; (b) performing plasma pretreatment on the resin layer; (c) forming a tie coat layer on the resin layer subjected to plasma pretreatment; and (d) forming a copper layer on the tie coat layer; In the step (b), the binding ratios of C-C, C-N, C-O and C=O appearing on the surface of the resin layer during peeling between the resin layer and the tie coat layer are each 40at% It corresponds to the step of performing plasma treatment so as to be more than, 25at% or more, 7at% or more, and 10at% or more.

The step (b) may be a step of performing plasma pretreatment so that the roughness appearing on the surface of the tie coat layer becomes 12 nm to 19 nm after the exfoliation.

The step (b) may be a step of performing plasma pretreatment so that the roughness appearing on the surface of the tie coat layer becomes 12 nm to 19 nm after the exfoliation.

Step (b) may be a step of performing plasma pretreatment under a voltage condition of 2.0 to 2.5 kV using nitrogen gas.

According to one aspect of the present invention, it is possible to obtain a flexible copper-clad laminate having excellent quality by improving the high-temperature peel strength between the resin layer and the tie coat layer constituting the flexible copper-clad laminate.

According to another aspect of the present invention, by improving the quality of the flexible copper clad laminate, the quality of the printed circuit board manufactured by forming a wiring pattern on the copper layer of the flexible copper clad laminate can also be significantly improved.

The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and together with the detailed description of the present invention serve to further understand the technical spirit of the present invention, the present invention is should not be construed as being limited only to
1 is a cross-sectional view of a flexible copper clad laminate according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the configuration shown in the embodiments and drawings described in the present specification is merely the most preferred embodiment of the present invention and does not represent all of the technical spirit of the present invention, so at the time of the present application, various It should be understood that there may be equivalents and variations.

1, a flexible copper-clad laminate and a manufacturing method thereof according to an embodiment of the present invention will be described.

1 is a cross-sectional view of a flexible copper clad laminate according to an embodiment of the present invention.

Referring to FIG. 1 , in the flexible copper-clad laminate according to an embodiment of the present invention, a resin layer 1 , a tie coat layer 2 and a copper layer 3 are sequentially laminated.

The resin layer 1 corresponds to a film made of polyimide (PI) resin.

The resin layer (1) used in the present invention has a binding ratio of C-C, C-N, C-O and C=O appearing on the surface of 75at% or more, 20at% or more, 5at% or more, and 10at% or more, respectively.

The tie coat layer (2) is formed on the resin layer (1) to improve adhesion between the resin layer (1) and the copper layer (3), and includes nickel (Ni), molybdenum (Mo) and niobium ( made of an alloy containing Nb).

The tie coat layer 2 may be deposited on the resin layer 1 by a sputtering method, which is a type of dry plating method, and is preferably formed to a thickness of approximately 5 nm to 35 nm.

When the thickness of the tie coat layer (2) is less than 5 mm, the resin layer (1) and the tie coat layer (2) in the process of forming a wiring pattern through etching of a flexible copper clad laminate for the manufacture of a printed circuit board There is a risk of lowering the peel strength between them.

On the contrary, when the thickness of the tie coat layer 2 exceeds 35 mm, there is a problem in that the etching process is not easy.

The copper layer 3 is formed on the tie coat layer 2 and includes a copper seed layer 3a and a copper coating layer 3b. The copper seed layer 3a is a layer formed by depositing on the tie coat layer 2 by a sputtering method, and is formed to a thickness of approximately 10 nm to 100 nm.

The copper film layer 3b is a layer formed by an electrolytic plating method on the copper seed layer 3a, and is preferably formed to a thickness in the range of about 5 μm to 15 μm.

Meanwhile, in the present invention, a plasma pretreatment process for the resin layer 1 is performed prior to the formation of the tie coat layer 2 in order to remove contaminants on the surface of the resin layer 1 and modify the surface.

The plasma pretreatment process may be performed using a DC plasma process, an RF plasma process, or an Ion plasma process, and may be performed in a voltage range of approximately 2.0 to 2.5 kV using nitrogen (N ₂ ) gas.

As such, in the plasma pretreatment process, by limiting detailed process conditions, the physical properties of the flexible copper clad laminate can be controlled.

Referring to Table 1 below, high-temperature peel strength test results for flexible copper-clad laminates manufactured using the resin layer 1 that have undergone the plasma pretreatment process are shown.

Preparation of evaluation samples

A tie coat layer (NiMoNb) was deposited to a thickness of 20 nm by sputtering on one surface of a polyimide (PI) substrate used as a substrate, and a copper seed layer was deposited thereon to a thickness of 60 nm. Then, a copper film layer was formed to a thickness of 12 μm using electroplating.

If the PI surface is surface-modified through plasma treatment before the tie coat layer is formed, the flexible copper-clad laminate after high-temperature heat treatment has excellent high-temperature peel strength characteristics. Plasma treatment changes the ratio of functional groups on the PI surface, which results in different peel strength between the metal layer and the resin layer.

How to measure physical properties

- Peel strength: Peel strength was measured by a method based on IPC-TM-650, NUMBER2.4.9, and after 8 measurements using UTM equipment, the average of the remaining values excluding max and min values was determined. . As an index of heat resistance, the film substrate on which a lead of 1 mm was formed was left in an oven at 150° C. for 168 hours, and the peel strength was evaluated.

- Chemical bond state (XPS analysis): The chemical bond state of the atom was confirmed by measuring the kinetic energy of the atom's core electron by irradiating X-rays (AXIS-His, KRATOS).

- Surface roughness (AFM analysis): The surface roughness was observed using a micro tip (NANO Stationall. Surface imaging system, Inc.).

According to the experimental results, when peeling between the resin layer 1 and the tie coat layer 2 constituting the flexible copper clad laminate according to an embodiment of the present invention, the surface of the tie coat layer 2 (resin layer before peeling) If the binding ratios of C-C, C-N, C-O and C=O appearing in (1) on the side in contact with (1) are 40at% or more, 25at% or more, 7at% or more, and 10at% or more, respectively, the It can be seen that the high-temperature peel strength is high.

In addition, according to the experimental results, when the roughness of the surface of the tie coat layer 2 (the surface that was in contact with the resin layer 1 before peeling) measured after peeling was in the range of 12 nm to 19 nm, that of the flexible copper clad laminate It can be confirmed that the high-temperature peel strength is sufficiently high.

On the other hand, a desired wiring pattern can be formed by etching the copper layer 2 and the tie coat layer 2 of the flexible copper clad laminate having the above-described physical properties using a method such as photo etching, thereby having excellent physical properties. A printed circuit board (PCB) can be obtained.

In the above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited thereto and will be described below with the technical idea of the present invention by those of ordinary skill in the art to which the present invention pertains. It goes without saying that various modifications and variations are possible within the scope of equivalents of the claims.

1: polymer film 2: tie coat layer
3: copper layer 3a: copper seed layer
3b: copper film layer

Claims (14)

resin layer;
a tie coat layer formed on the resin layer; and
a copper layer formed on the tie coat layer;
The binding ratios of CC, CN, CO and C=O appearing on the surface of the tie coat layer during peeling between the resin layer and the tie coat layer are respectively 40at% or more, 25at% or more, 7at% or more, and Flexible copper-clad laminates with 10at% or more. According to claim 1,
The resin layer,
The resin layer is a flexible copper-clad laminate, characterized in that made of polyimide (PI) resin. 3. The method of claim 2,
The resin layer is plasma-treated,
A flexible copper-clad laminate, characterized in that the binding ratios of CC, CN, CO and C=O appearing on the surface of the resin layer before the plasma treatment are 75at% or more, 20at% or more, 5at% or more, and 10at% or more, respectively. According to claim 1,
The tie coat layer,
A flexible copper-clad laminate, characterized in that the roughness appearing on the surface after the peeling is 12 nm to 19 nm. According to claim 1,
The tie coat layer,
A flexible copper-clad laminate, characterized in that it is made of an alloy containing Ni, Mo and Nb. According to claim 1,
The tie coat layer,
Flexible copper-clad laminate, characterized in that it is formed to a thickness of 5nm to 35nm. According to claim 1,
The copper layer is
a copper seed layer formed on the tie coat layer; and
and a copper film layer formed on the copper seed layer. 8. The method of claim 7,
The copper seed layer comprises:
Flexible copper-clad laminate, characterized in that it is formed to a thickness of 10nm to 100nm. 8. The method of claim 7,
The copper film layer,
Flexible copper-clad laminate, characterized in that it is formed to a thickness of 5㎛ to 15㎛. A printed circuit board having a wiring pattern formed on the flexible copper-clad laminate according to any one of claims 1 to 9. (a) preparing a polymer film constituting a resin layer;
(b) performing plasma pretreatment on the resin layer;
(c) forming a tie coat layer on the resin layer subjected to plasma pretreatment; and
(d) forming a copper layer on the tie coat layer; includes,
In the step (b), the binding ratio of CC, CN, CO and C=O appearing on the surface of the resin layer upon peeling between the resin layer and the tie coat layer is 40at% or more, 25at%, respectively More than, 7at% or more, and a method of manufacturing a flexible copper-clad laminate which is a step of performing plasma treatment so that it is more than 10at%. 12. The method of claim 11,
Step (b) is,
and performing plasma pretreatment so that the roughness appearing on the surface of the tie coat layer becomes 12 nm to 19 nm after the peeling. delete 12. The method of claim 11,
Step (b) is,
Method of manufacturing a flexible copper-clad laminate, characterized in that the step of performing plasma pretreatment under a voltage condition of 2.0 to 2.5 kV using nitrogen gas.

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