KR20130088347A - Printed circuit board and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A printed circuit board (PCB) and a manufacturing method thereof are provided to implement fine pitch by transferring a conductive sheet on a film layer. CONSTITUTION: An electrode pad (115) is included on a base circuit board. A film layer (120) is formed on the base circuit board. The base circuit board and a conductive sheet are compressed. The conductive sheet is inserted in an opening unit. A conductive post (142) is formed on the electrode pad.

Description

Printed circuit board and method for manufacturing the same

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, and more particularly, to a printed circuit board and a method of manufacturing the same, which can realize a conductive post having a fine pitch and a large aspect ratio.

In recent years, with the development of the electronics industry, high performance, high functionalization, and miniaturization of electronic components are required. Accordingly, the demand for high integration, thinning, and fine circuit patterning has also emerged in response to miniaturization and technology integration in surface mount component substrates. .

In particular, a wire bonding method and a flip chip bonding method are used for the electrical connection between the semiconductor chip and the printed circuit board in the surface mounting technology of the electronic component on the substrate. Because of the need to connect to a printed circuit board using wires, the size of the module is increased and an additional process is required, and the flip chip bonding method is widely used because there is a limit in the implementation of the fine pitch of the circuit pattern.

Here, the flip chip bonding method is to form an external connection terminal (i.e., bump) made of gold, solder, or other metal material on a semiconductor chip, and a bump formed semiconductor chip as opposed to a conventional mounting method by wire bonding. Flip to mount the surface facing the substrate direction.

This flip chip bonding method has seen considerable achievement by the application of flip chip technology in place of wire bonding, but it is still difficult to refine the bump pitch.

Accordingly, in order to make a finer bump pitch than the solder bump forming method, a technology of forming a metal post using an electrocopper plating process instead of solder paste or solder balls has been developed. In the related art, a base substrate having an electrode pad is developed. After applying a mask having an opening to expose the electrode pads on it, the solder paste was filled into the opening, the mask was removed, and the solder paste was reflowed to prepare a metal post.

However, according to the related art, it is important to accurately align the mask on the base substrate, but as the circuit pattern gradually progresses to fine pitch, it is difficult to accurately align the mask on the base substrate.

In addition, the pitch of the metal post (pitch) is reduced to a certain level or less, there is a problem that it is difficult to implement a metal post having a high aspect ratio. That is, since the mask is made of metal, it is difficult to process fine holes in the mask, and the processing variation of the mask is difficult to keep up with the speed at which the circuit pattern becomes fine.

The idea of the present invention is to compress the conductive sheet to the base substrate on which the film layer having the open portion is formed, insert the conductive sheet into the open portion, and then reflow the conductive sheet in the state where the film layer is formed to fine pitch. The present invention provides a printed circuit board and a method of manufacturing the same, which can more easily implement a conductive post having a large aspect ratio.

To this end, a method of manufacturing a printed circuit board according to an embodiment of the present invention includes forming a film layer having an open part exposing the electrode pad on a base substrate having an electrode pad; Providing a conductive sheet; Pressing the base substrate and the conductive sheet to insert the conductive sheet into the open portion; Bonding the electrode pad and the conductive sheet to form a conductive post on the electrode pad; Removing the film layer.

The conductive sheet may be made of a flexible material.

The conductive sheet is made of copper (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni) or molybdenum (Mo). It may be made of any one or more than one alloy.

The thickness of the conductive sheet may be thicker than the thickness of the film layer.

After forming the film layer, the method may further include applying flux on the film layer including the open part.

After inserting the conductive sheet into the open portion, the method may further include removing the conductive sheet remaining on the upper portion of the film layer without being inserted into the open portion.

In the forming of the conductive post on the electrode pad, the conductive sheet may be bonded to the electrode pad by reflowing the conductive sheet.

Removing the conductive sheet remaining on the upper portion of the film layer may be performed simultaneously with reflowing the conductive sheet to bond the conductive sheet on the electrode pad.

The conductive post may have an aspect ratio of 1.25 or more.

The forming of the film layer may include forming a resist having an opening on the base substrate including the electrode pads to expose the electrode pads; The method may include forming a film layer having an open part exposing the electrode pad on the resist.

On the other hand, a printed circuit board according to an embodiment of the present invention is a base substrate having an electrode pad; A resist formed with an opening exposing the electrode pad on the base substrate; Conductive posts are formed on the electrode pads having a predetermined height, the upper surface of the conductive posts is made of a curved surface.

The conductive post may have an aspect ratio of 1.25 or more.

The conductive post may be any one of copper (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni), or molybdenum (Mo). It may consist of one or more alloys.

As described above, according to the printed circuit board and the manufacturing method thereof according to an embodiment of the present invention, after the conductive sheet is pressed onto the base substrate on which the film layer having the open portion is formed, the conductive sheet is inserted into the open portion, and then the film layer is By reflowing the conductive sheet in the formed state, fine pitch is possible, and the conductive post having a large aspect ratio can be easily implemented.

More specifically, exposing and developing the film layer can significantly increase the accuracy of alignment and reduce the processing variation very small than aligning the mask (prior art) to the substrate. have.

In addition, since the conventional mask is made of metal, it is difficult to process fine holes in the mask, but since the film layer is easier to process fine holes by exposure and development processes, it is possible to easily implement a conductive post having a fine pitch. There is an advantage.

In addition, according to the prior art, since the process of reflowing the solder paste is performed after removing the mask, there is a problem that the metal post is realized in the shape of a circle due to the surface tension during the reflow process. Since the film layer guides the conductive sheet during the reflow process, the conductive post having a large aspect ratio can be easily implemented.

1 is a cross-sectional view of a printed circuit board according to an embodiment of the present invention.
2 to 9 are cross-sectional views illustrating a manufacturing process of a printed circuit board according to an embodiment of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

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

1 is a cross-sectional view of a printed circuit board according to an embodiment of the present invention.

As shown in FIG. 1, the printed circuit board includes a base substrate 110, a resist 117, and a conductive post 142.

First, the base substrate 110 is a means for supporting a printed circuit board, prepreg, polyimide, polyethylene terephthalate (PET, polyethyeleneterepthalate), cyanide ester, ABF (Ajinomoto) It may be made of various materials such as build up film) or epoxy, which have a small electrical conductivity and hardly allow a current to pass through.

Here, the configuration of the printed circuit board as shown in FIG. 1 is merely exemplary, and the printed circuit board may be a single-sided printed circuit board, a double-sided printed circuit board, and a multilayer printed circuit board, and the technical features of the present invention are the same. Can be applied.

The electrode pad 115 may be formed on the upper surface of the base substrate 110. The electrode pad 115 may be formed in a subtractive method, an additive method, or a semi additive method. It can be formed using various techniques.

In this case, the electrode pad 115 may include copper (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni), or molybdenum ( Metal) such as Mo).

The resist 117 may have an opening OP exposing the electrode pad 115 on the base substrate 110. In this case, the resist 130 may be made of various photosensitive materials such as a photo resist, a photo solder resist, or a dry film, and the like may be replaced with various materials. Of course.

The conductive post 142 is formed to have a predetermined height on the electrode pad 115, and the upper surface may be formed of a curved surface.

In more detail, the conductive post 142 forms the film layer 120 having the open portion CP formed on the resist 117 to be described in detail below, and the base substrate 110 having the film layer 120 formed thereon. After pressing and inserting the conductive sheet 140 into the substrate, the conductive sheet 140 may be formed by reflowing the conductive sheet 140 in a state where the film layer 120 is present. As such, since the conductive sheet 140 is reflowed in the state where the film layer 120 is present, the top surface of the conductive post 142 may be formed as a curved surface.

In addition, the conductive post 142 may have an aspect ratio of 1.25 or more. In more detail, the aspect ratio means the height h of the conductive posts 142 / the diameter of the conductive posts 142. In the related art, there is a problem that it is difficult to form a conductive post having a small diameter and a large height. In one embodiment of the present invention, since the film layer 120 guides the conductive sheet 140 during the reflow process, the conductive post 142 having a large aspect ratio may be implemented without disturbing the shape.

In addition, the conductive post 142 may be made of copper (Cu), in addition to silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel ( Ni) or molybdenum (Mo), and the like.

Hereinafter, a manufacturing process of a printed circuit board according to an embodiment of the present invention will be described.

2 to 9 are cross-sectional views showing a manufacturing process of a printed circuit board according to an embodiment of the present invention.

Referring to FIG. 1, a base substrate 110 having an electrode pad 115 is prepared. In this case, a resist 117 having an opening OP may be further formed on the base substrate 110 to expose the electrode pad 115.

Here, the base substrate 110 is a means for supporting a printed circuit board, prepreg, polyimide, polyethylene terephthalate (PET, polyethyeleneterepthalate), cyanide ester, ABF (Ajinomoto) It may be made of various materials such as build up film) or epoxy, which have a small electrical conductivity and hardly allow a current to pass through.

In addition, an electrode pad 115 may be formed on an upper surface of the base substrate 110. The electrode pad 115 may be formed in a subtractive method, an additive method, or a semi additive method. It can be formed using a variety of methods such as. In this case, the electrode pad 115 may include copper (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni), or molybdenum ( It may be made of various metal materials such as Mo).

The resist 117 is a means in which the opening OP is formed to expose the electrode pad 115 on the base substrate 110. The photoresist, photo solder resist, or dry film is formed. It may be made of various photosensitive materials such as a dry film, and the like, and the present invention may be substituted with various materials.

Next, referring to FIG. 2, a film layer 120 having an open portion CP exposing the electrode pad 115 is formed on the resist 117. Here, the film layer 120 may be made of various photosensitive materials such as photo resist, photo solder resist, or dry film, and the like, and the film layer 120 may be replaced with various materials. Of course.

Next, as shown in FIG. 3, the flux 130 is applied to the film layer 120 including the open portion CP by using a spray. Here, the flux 130 is a mixed salt used to make a thin layer of salts dissolved on the surface of the metal for the purpose of preventing the molten metal surface from contacting the atmosphere when dissolving the metal or alloy, one embodiment of the present invention In the example, when the metal material (conductive sheet) is bonded onto the electrode pad 115 by soldering or welding, the oxidation of the adhesive surface is prevented so that the metal material (conductive sheet) and the electrode pad 115 are completely made. Used to bond.

Then, as shown in FIG. 4, the conductive sheet 140 is provided. Here, the conductive sheet 140 is a sheet (copper) (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni) or molybdenum (Mo) may be made of any one or more than one alloy.

In this case, the conductive sheet 140 may be made of a soft material having a soft strength. For example, in more detail, the conductive sheet 140 may be formed to have a lower strength than the mechanical strength of the general metal. If the mechanical strength of the general metal (young's modulus of stainless steel) is 200 GPa, the conductive sheet 140 The mechanical strength of (Tin's young's modulus) can be made up to 50 GPa.

Next, as shown in FIG. 5, the base substrate 110 and the conductive sheet 140 are compressed to insert the conductive sheet 140 into the open portion CP of the film layer 120. That is, the conductive sheet 140 is inserted into the open portion CP of the film layer 120 by using a physical external force, wherein the thickness of the conductive sheet 140 is formed to be thicker than the thickness of the film layer 120. The conductive sheet 140 may be completely inserted into the open portion CP of the film layer 120. In this case, the thickness of the conductive sheet 140 may be formed in a range of about several tens to several hundred μm.

Thereafter, as shown in FIG. 6, the conductive sheet 140 remaining on the upper portion of the film layer 120 is removed. More specifically, the film is not inserted into the open portion CP of the film layer 120. The conductive sheet 140 remaining on the top of the layer 120 is removed using a squeegee 150 or the like.

Next, as shown in FIG. 7, the conductive pad 141 is formed on the electrode pad 115 by bonding the electrode pad 115 and the conductive sheet 140 to each other. In more detail, the conductive sheet 140 may be bonded to the electrode pad 115 by reflowing and melting the conductive sheet 140. In this case, the film layer 120 may be formed during the reflow process. Since the conductive sheet 140 remains without being removed to guide the conductive sheet 140, the conductive sheet 140 may maintain the existing shape to implement the conductive post 142 having a large aspect ratio.

Meanwhile, in one embodiment of the present invention, after removing the conductive sheet 140 remaining on the upper portion of the film layer 120, the process of reflowing the conductive sheet 140 is sequentially performed. Removing the conductive sheet 140 remaining on the upper portion of the film layer 120 may be performed simultaneously with reflowing the conductive sheet 140 and bonding the conductive sheet 140 on the electrode pad 115. It is possible.

That is, when the conductive sheet 140 remaining on the upper portion of the film layer 120 is removed, the heating operation is also performed to remove the conductive sheet 140 remaining on the upper portion of the film layer 120 and the open portion CP. Melting and bonding operation of the conductive sheet 140 in the () can be performed at the same time.

Next, as shown in FIG. 8, the conductive layer 142 is completed by removing the film layer 120. Here, the conductive post 142 may have an aspect ratio of 1.25 or more. In more detail, the aspect ratio means the height h of the conductive posts 142 / the diameter of the conductive posts 142. In the related art, there is a problem that it is difficult to form a conductive post having a small diameter and a large height. In an embodiment of the present invention, the conductive post 142 having a fine pitch may be easily implemented by the exposure and development processes of the film layer 120, and the film layer 120 may be the conductive sheet 140 even during the reflow process. Since there is a guide, there is an advantage that can implement a conductive post 142 having a large aspect ratio without disturbing the shape.

The foregoing detailed description is illustrative of the present invention. In addition, the foregoing description merely shows and describes preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, it is possible to make changes or modifications within the scope of the concept of the invention disclosed in this specification, the disclosure and the equivalents of the disclosure and / or the scope of the art or knowledge of the present invention. The foregoing embodiments are intended to illustrate the best mode contemplated for carrying out the invention and are not intended to limit the scope of the present invention to other modes of operation known in the art for utilizing other inventions such as the present invention, Various changes are possible. Accordingly, the foregoing description of the invention is not intended to limit the invention to the precise embodiments disclosed. It is also to be understood that the appended claims are intended to cover such other embodiments.

110. Base substrate 115. Electrode pad
117. Resist 120. Film Layer
130. Flux 140. Conductive Sheet
150. Squeegee

Claims (13)

Forming a film layer having an open portion exposing the electrode pad on a base substrate having an electrode pad;
Providing a conductive sheet;
Pressing the base substrate and the conductive sheet to insert the conductive sheet into the open portion;
Bonding the electrode pad and the conductive sheet to form a conductive post on the electrode pad;
Removing the film layer;
And a step of forming the printed circuit board.
The method of claim 1,
The conductive sheet,
A method of manufacturing a printed circuit board made of a flexible material.
The method of claim 1,
The conductive sheet,
One or more of copper (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni) or molybdenum (Mo) Method of manufacturing a printed circuit board made of an alloy.
The method of claim 1,
The thickness of the conductive sheet,
Method of manufacturing a printed circuit board thicker than the thickness of the film layer.
The method of claim 1,
After the step of forming the film layer,
The method of manufacturing a printed circuit board further comprising the step of applying a flux on the film layer including the open portion.
The method of claim 1,
After inserting the conductive sheet into the open portion,
And removing the conductive sheet remaining on top of the film layer without being inserted into the open portion.
6. The method according to claim 1 or 5,
Forming a conductive post on the electrode pad,
And reflowing the conductive sheet to bond the conductive sheet on the electrode pad.
The method of claim 7, wherein
Removing the conductive sheet remaining on the upper portion of the film layer,
And reflowing the conductive sheet to bond the conductive sheet on the electrode pad.
The method of claim 1,
The conductive post,
A method of manufacturing a printed circuit board having an aspect ratio of 1.25 or more.
The method of claim 1,
Forming the film layer,
Forming a resist having an opening on the base substrate having the electrode pads to expose the electrode pads;
And forming a film layer having an open portion exposing the electrode pad on the resist.
A base substrate having electrode pads;
A resist formed with an opening exposing the electrode pad on the base substrate;
A conductive post formed on the electrode pad and having a predetermined height;
The upper surface of the conductive post is a curved printed circuit board.
The method of claim 11,
The conductive post,
A printed circuit board having an aspect ratio of 1.25 or more.
The method of claim 11,
The conductive post,
One or more of copper (Cu), silver (Ag), gold (Au), aluminum (Al), iron (Fe), titanium (Ti), tin (Sn), nickel (Ni) or molybdenum (Mo) Printed circuit board made of alloy.

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