KR100797699B1 - Printed circuit board and preparing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board and a method of manufacturing the same. A flash etching process for etching and removing a metal seed layer in a region where a patterned metal circuit layer is not formed during a conventional pattern circuit layer manufacturing process. It is characterized by forming an etch-resist layer on the patterned metal circuit layer prior to performing the etching to selectively etch away only certain areas.

According to the present invention, while minimizing damage to the metal circuit layer during the flash etching process, it is possible to selectively remove the unnecessary metal seed layer completely, thereby achieving a microcircuit with high reliability through a more economical and simple process. .

Printed circuit board, metal circuit layer, metal seed layer, flash etching, etching resist

Description

Printed circuit board and manufacturing method thereof

1A to 1F are cross-sectional views illustrating a process flow for explaining a manufacturing process of a printed circuit board according to an exemplary embodiment of the prior art.

2 is a cross-sectional view schematically illustrating a state of a circuit layer of a printed circuit board according to an exemplary embodiment of the prior art.

3 is a cross-sectional view schematically illustrating a state of a circuit layer of a printed circuit board according to another exemplary embodiment of the prior art.

4A to 4E are cross-sectional views illustrating a process flow for explaining a manufacturing process of a printed circuit board according to an embodiment of the present invention.

5 is an enlarged view illustrating a state in which a self-assembled molecular layer is formed as an etching-resist layer on a metal circuit layer according to an embodiment of the present invention.

FIG. 6 is a view schematically showing a state in which a self-assembled molecular layer formed as an etch-resist layer on a metal circuit layer is diffused along a part of a side of the metal circuit layer according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view schematically illustrating a state of a circuit layer upon application of a flash etching process after forming an etching-resist layer on a metal circuit layer according to the method of the present invention.

※ Explanation of code about main part of drawing ※

10: resin substrate 20: metal seed layer

30: dry film 40: metal circuit layer

100: flat stamp 101: etching-resist

200: resin substrate 201: metal seed layer

202: metal circuit layer

The present invention relates to a method of manufacturing a printed circuit board and a printed circuit board manufactured therefrom. More specifically, the present invention relates to a printed circuit board and a method for manufacturing the same, by forming an etching resist on the metal circuit layer prior to flash etching, thereby selectively minimizing a specific area by increasing the size of the circuit. will be.

In recent years, printed circuit boards have become smaller and thinner, and thus the size of via holes connecting metal wirings and electronic devices is becoming smaller.

In the manufacture of printed circuit boards, a tenting method of forming a circuit by etching copper and a semiadditive method of forming a circuit by plating copper are widely used, and have a wiring width of 30 μm or less. In the circuit, the semiadditive process is mainly used because of the limitation of wet etching.

In the semi-additive process, after forming a copper circuit by plating, a process of flash-etching removes a non-circuit copper thin film layer. The top edge of the plated copper circuit layer The edge portion is also eroded at the same time, and the circuit shape is deteriorated, and undercut occurs due to the difference in etching rates between the copper thin film layer and the copper circuit layer. Due to these problems, the semi-additive method has a difficulty in forming a circuit having a wiring width of 10 μm or less.

A process of forming a circuit using the semi-additive method according to the prior art will be described with reference to FIGS. 1A to 1F.

First, a metal layer, for example, a copper thin film layer 20, is formed outside the resin substrate, that is, the insulating layer 10 through lamination or electroless plating (see FIG. 1A). Next, the dry film 30 is attached on the copper thin film layer 20 (see FIG. 1B), and an artwork film (not shown) of a wiring pattern is adhered on the dry film 30, and then exposed and developed. The dry film 30 of the portion where the circuit is to be formed is removed through the process (see FIG. 1C). The copper circuit layer 40 is formed on the exposed portion through electroplating (see FIG. 1D). At this time, the copper thin film layer 20 serves as a seed layer. When the plating is finished, the remaining dry film 30 is removed through a peeling process (see FIG. 1E). Finally, the circuit is completed by removing the seed copper layer 20 in the portion other than the circuit by flash etching.

However, in the semi-additive method described above, the height of the initial electroplating layer should be set high in consideration of the etching of not only the seed layer but also the circuit layer during the flash etching process. Wasted. In addition, since the shape of the circuit is deteriorated due to erosion of the upper edge portion of the circuit layer 40 generated during flash etching (see FIG. 2), the etching rates of the seed layer 20 and the circuit layer 40 are different. Undercut occurs (see FIG. 3). Due to the problems described above, it is difficult to achieve a circuit of 10 μm or less by the conventional semi-additive method.

Therefore, there is a need for a new manufacturing method for processing a circuit in excellent form in order to implement a narrower microcircuit (for example, 10 to 15 μm) in a printed circuit board.

Accordingly, in the present invention, extensive research has been conducted to solve the above problems. As a result, an etching-resist layer is formed on a patterned metal circuit layer before performing flash etching in a conventional pattern circuit layer manufacturing process. It has been found that only certain unnecessary areas can be etched selectively, and the present invention has been completed based on this.

Accordingly, an object of the present invention is to provide a printed circuit board and a method for manufacturing the same, which can completely remove unnecessary metal seed layers while minimizing damage to the metal circuit layer during a flash etching process.

Another object of the present invention relates to a printed circuit board and a method of manufacturing the same, which can implement a microcircuit with high reliability.

In order to achieve the above object and other objects, according to an aspect of the present invention,

(a) forming a metal seed layer on the resin substrate;

(b) forming a patterned metal circuit layer on the metal seed layer;

(c) forming an etch-resist layer on the patterned metal circuit layer; And

(d) etching to remove the metal seed layer in the region where the patterned metal circuit layer is not formed;

Provided is a method of manufacturing a printed circuit board comprising a.

Here, the metal is preferably copper.

Preferably, the metal seed layer may be formed through electroless metal plating.

Preferably, step (b) is:

b1) applying a photoresist on the metal seed layer, and exposing and developing the photoresist to expose the metal seed layer of the portion where the circuit pattern is to be formed to the outside;

b2) forming a circuit pattern on the externally exposed metal seed layer by electrolytic metal plating, and

b3) removing the photoresist,

It may include.

On the other hand, step (c) may be performed by printing the etching-resist on the patterned metal circuit layer, preferably using a flat stamp on which the etching-resist liquid is applied. Preferably, the etching-resist liquid includes self-assembled molecules. More preferably, the self-assembled molecule is a self-assembled molecule of alkan thiol.

The etch-resist layer may also be formed on at least a portion of the top and side surfaces of the patterned metal circuit layer.

The step (d) is preferably a hydrogen peroxide / acid chloride, cupric chloride, _{^{ferric, CN - / O 2, NBSA}} (3-nitrobenzene sulfonic acid) / PEI (polyethylenimine) and is selected from the group consisting of a mixture thereof It can be carried out using an etching solution containing an etching component.

According to another aspect of the present invention,

(a) a resin substrate;

(b) a patterned metal layer formed on the resin substrate and comprising a metal seed layer and a metal circuit layer; And

(c) an etch-resist layer formed on the patterned metal layer;

There is provided a printed circuit board comprising a.

Here, the metal is preferably copper.

Preferably, the metal seed layer may be an electroless metal plating layer.

Preferably, the metal circuit layer may be an electrolytic metal plating layer.

On the other hand, the etching-resist layer is preferably made of a self-assembled molecule, more preferably, the self-assembled molecule may be a self-assembled molecule of the alkane thiol.

The etch-resist layer may be preferably formed on at least a portion of the top and side surfaces of the metal circuit layer.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As described above, the present invention forms an etching resist on the surface of the metal circuit layer before flash etching, thereby selectively removing unnecessary metal seed layers and completely removing the unnecessary metal seed layer during the flash etching process. Provided are a printed circuit board and a method of manufacturing the same, which can implement a fine circuit with high reliability through a simple and simple process.

4A to 4E, a process of manufacturing a printed circuit board using a self assembly molecule film as an etching-resist layer using a microcontact-printing technique according to an exemplary embodiment of the present invention. Although schematically shown, it is a matter of course that the present invention is not limited thereto.

First, an elastomer mold such as a planar stamp 100, for example, a polydimethylsiloxane (PDMS) mold, which is generally employed in microcontact printing technology, is prepared (see FIG. 4A).

Next, an etch-resist 101 is applied onto the flat stamp and dried (see FIG. 4B). In this case, as the etching-resist 101, an ink solution including a self assembly molecule may be preferably used. The self-assembled molecule is particularly preferably an alkan thiol self-assembled molecule, but has self-assembling properties, the terminal functional group is bonded to the metal of the metal circuit layer, and the alkyl chain portion is formed by van der Waals forces. Any material that can form a resist layer by dense together can be used without particular limitation. In the present invention, the longer the length of the alkyl carbon chain of the self-assembled molecules to be used as an etch-resist in the metal circuit layer, and in the case of the alkane thiol, preferably having a carbon chain number of about 20 or more good.

Next, using the flat plate stamp 100, an etching-resist layer is formed on the patterned metal circuit layer 202 of the resin substrate 200 on which the metal seed layer 201 and the patterned metal circuit layer 202 are formed. 101) (see FIG. 4C). Preferably, the metal may be copper. The etch-resist 101 may also be formed up to at least a portion of the side as well as the top of the metal circuit layer 202.

Preferably, as shown in Figs. 5 and 6, the etching-resist made of the self-assembled molecular layer by bringing the flat stamp 100 coated with the self-assembled molecular ink onto the surface of the patterned metal circuit layer 202 ( 101). During this printing process, a highly assembled self-assembled molecular layer on the surface of the metal circuit layer 202 is formed in a short time (about 0.5 seconds). In particular, since the self-assembled molecular layer has a property of diffusing along the side in the state where the flat stamp 100 and the upper end of the metal circuit layer 202 are in close contact (see FIG. 6), the metal circuit to be protected by using such diffusivity In consideration of the layer area, printing process conditions such as printing time and temperature may be appropriately adjusted according to the height of the metal circuit layer, the type of the etching-resist liquid used, the concentration, and the like. For example, the etching-resist is selectively formed only on the upper portion of the metal circuit layer to protect only the upper end of the circuit, and the etching-resist is diffused to form near the lower end along the side of the circuit having a height of 10 μm or more. In addition, in consideration of protecting at least a part of the side surface, the printing time may be selected from about 0.5 seconds to about 10 minutes, but may also be appropriately adjusted according to the type, concentration, printing temperature, etc. of the etching-resist actually used. It will be apparent to one skilled in the art.

Meanwhile, the resin substrate 200 on which the metal seed layer 201 and the patterned metal circuit layer 202 are formed is not particularly limited, and according to a conventional process known in the art, for example, a semiadditive process It may be manufactured according to the provided.

For example, the metal seed layer 201 may be formed on the resin substrate 200 through a conventional electroless metal plating method. In addition, the patterned metal circuit layer 202 is coated with a photoresist (not shown) on the metal seed layer 201, and exposed and developed to form the metal seed layer 201 of the portion where the circuit pattern is to be formed. After exposing to the outside, a circuit pattern may be formed on the externally exposed metal seed layer 201 through a conventional electrolytic metal plating method, and then removed by photoresist.

Next, when the printing process is finished and the flat stamp 100 is separated from the metal circuit layer 202, only the metal seed layer 201 of the portion where the patterned metal circuit layer 202 is not formed, that is, the circuit, is not formed. Exposed (see FIG. 4D).

Finally, the exposed metal seed layer 201 is removed by etching through a conventional flash etching process (see FIG. 4E). The etching solution used in the flash etching process is not particularly limited, and for example, hydrogen peroxide / hydrochloric acid (H ₂ O ₂ / HCl) etching solution widely used for flash etching of a printed circuit board, or copper chloride (CuCl) may be used. may be used alone or in appropriate combination for an etching solution, such as _{/ O 2, NBSA (3-} nitrobenzene sulfonic acid) / PEI (polyethylenimine) on a ^_purpose-2) common copper etching solution or CN, such as ferric chloride (FeCl _3).

The etching process is schematically shown in FIG. The etching of the metal circuit layer 202 is prevented by the etching-resist layer 101 formed up to the top and side portions of the metal circuit layer 202. As a result, it is possible to erode only the region of the metal seed layer 201 in the portion other than the circuit without changing the thickness of the circuit.

Here, only the cross-section of the resin substrate has been described as an example, but it is apparent that the above-described process can be applied to both sides of the substrate. In addition to the circuit forming process, a conventional manufacturing process such as a lamination process applied to a conventional printed circuit board is It will be readily understood by those skilled in the art that further may be performed.

As described above, according to the method of the present invention, a circuit having excellent shape can be formed while using an existing circuit forming method, for example, a semiadditive method.

In addition, the etching-resist formed on the surface of the metal circuit layer, preferably the self-assembled molecular layer, does not affect the properties of the device within only a few nanometers (average 2 nm), and only changes the surface properties, thus eliminating the need for a removal process.

In addition, unlike conventional microcontact printing technology, the printing process of the etch-resist is inexpensive and simple because it uses a flat stamp that does not require fine patterning. The reason why the micro-patterning of the flat stamp itself is not required is that the step between the metal layers previously formed, i.e., before the flash etching process for selectively removing only a few microns of metal seed layer in the printed circuit board manufacturing process is applied. This is because the height difference between the metal seed layer and the metal circuit layer can be used to selectively apply the etching-resist only to the metal circuit layer. In other words, during the printed circuit board process, which is performed on a relatively large scale in microns, by applying microcontact printing technology in a state where a pattern is already formed, it is possible to simply and quickly remove the metal seed layer while protecting the pattern. will be.

In addition, the flat stamp can be repeated hundreds of times using the PDMS.

The printing of the etch-resist takes a relatively very short time, and the adhesion time can be extended to selectively form the etch resist on the side of the circuit.

Although the present invention has been described in detail through specific embodiments, it is for explaining the present invention in detail, and the printed circuit board and its manufacturing method according to the present invention are not limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art.

As described above, according to the present invention, fine etching may be achieved by forming a fine etching resist on a circuit surface before flash etching, and there is an advantage that an etch factor is increased. In addition, it is possible to form a circuit pattern of high reliability to increase the frequency characteristics of the circuit can improve the signal transmission efficiency. In addition, it is possible not only to form a fine circuit with a line / space of 10/10 or less, but also to reduce the time and cost of the circuit plating process of the printed circuit board.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

Claims (16)

(a) forming a metal seed layer on the resin substrate; (b) forming a patterned metal circuit layer on the metal seed layer; (c) printing an etch-resist using a flat stamp on which the etch-resist solution is applied on the patterned metal circuit layer to form an etch-resist layer; And (d) etching to remove the metal seed layer in the region where the patterned metal circuit layer is not formed; Method of manufacturing a printed circuit board comprising a. The method of claim 1, wherein the metal is copper. The method of claim 1, wherein the metal seed layer is formed through electroless metal plating. The method of claim 1, wherein step (b) comprises: b1) applying a photoresist on the metal seed layer, and exposing and developing the photoresist to expose the metal seed layer of the portion where the circuit pattern is to be formed to the outside; b2) forming a circuit pattern on the externally exposed metal seed layer by electrolytic metal plating, and b3) removing the photoresist, Method of manufacturing a printed circuit board comprising a. delete The method of claim 1, wherein the etching-resist liquid comprises self-assembled molecules. The method of claim 6, wherein the self-assembled molecule is a self-assembled monomolecular molecule of alkan thiol. The method of claim 1, wherein the etch-resist layer is formed on part or all of the top and side surfaces of the patterned metal circuit layer. The method of claim 1, wherein the step (d) hydrogen peroxide / acid chloride, cupric chloride, _{^{ferric, CN - / O 2, NBSA}} (3-nitrobenzene sulfonic acid) / PEI (polyethylenimine) , and mixtures thereof A method of manufacturing a printed circuit board, characterized in that performed using an etchant containing the etching component selected. (a) a resin substrate; (b) a patterned metal layer formed on the resin substrate and comprising a metal seed layer and a metal circuit layer; And (c) an etch-resist layer composed of self-assembled molecules formed on the patterned metal layer; Printed circuit board comprising a. The printed circuit board of claim 10, wherein the metal is copper. The printed circuit board of claim 10, wherein the metal seed layer is an electroless metal plating layer. The printed circuit board of claim 10, wherein the metal circuit layer is an electrolytic metal plating layer. delete The printed circuit board of claim 10, wherein the self-assembled molecule is a self-assembled molecule of an alkane thiol. The printed circuit board of claim 10, wherein the etch-resist layer is formed on part or all of the top and side surfaces of the metal circuit layer.

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