KR20120102981A - Method for manufacturing printed circuit board - Google Patents

Abstract

PURPOSE: A method for manufacturing a printed circuit board is provided to maintain an interval between bumps by forming a flip chip bump into a metal bump using a plating process. CONSTITUTION: Plating resist forming an opening for bump formation is formed on a substrate(100). A patterned mask is arranged on the plating resist. A metal bump(130) is formed by plating the opening for bump formation. A complex solder resist layer(140) is formed on the substrate with a vacuum lamination process. The complex solder resist layer comprises first solder resist(140a) and second solder resist(140b). The first solder resist is a base film and the second solder resist is a cover film. The metal bump is exposed by eliminating the second solder resist.

Description

Method for manufacturing printed circuit board

The present invention relates to a method of manufacturing a printed circuit board.

Recently, as portable electronic products are miniaturized, spaces in which semiconductors are mounted on printed circuit boards are gradually decreasing. Therefore, in order to increase the mounting efficiency per unit area, the packaging method of the printed circuit board is becoming thin and small. A chip size package (CSP), a package about the same size as a semiconductor chip, has been developed and commercialized based on such a requirement.

However, recent trends in package development go beyond shrinking to the size of a semiconductor chip, stacking other semiconductor chips on top of a semiconductor chip, such as a stacked chip size package (SCSP), or multiple semiconductor chips with different functions in a single package. Arranged MCM (Multi-Chip Module) package is also being developed.

In addition, the wafer is not separated into individual chips, and after the manufacturing processes such as die bonding, molding, trimming, marking, etc., are carried out in a state where several semiconductor chips are attached thereto, Wafer level packages are also being developed, which are a method of cutting and making finished products immediately.

Among these highly integrated package technologies, in order to increase production efficiency, a pad of a chip and a pad of a board are directly connected without a wire in a wire bonding method of connecting a pad of a chip and a pad of a board by a wire. The use of flip-chip mounting technology is increasing.

Hereinafter, a flip chip bump forming process of a conventional printed circuit board will be described with reference to related drawings.

12 to 17 are cross-sectional views sequentially illustrating a method of manufacturing flip chip bumps of a printed circuit board using a printing process according to the prior art.

First, as shown in FIG. 12, the soldering resist layer 20 in which the bump formation opening part 25 was formed on the board | substrate 10 which has an outer layer circuit is formed.

13, the dry film 30 having the open part 35 corresponding to the bump forming opening 25 is coated on the formed solder resist layer 20.

Thereafter, as shown in FIG. 14, the solder paste 40 is printed on the bump forming openings 25 and the openings 35, and then the dry film 30 is removed as shown in FIG. 15.

Thereafter, as shown in FIG. 16, the solder bumps 45 are formed by the reflow process, and then a coining process is performed to form the upper surface of the solder bumps 45 in a flat form as shown in FIG. 17. .

However, the method of manufacturing a printed circuit board according to the prior art as described above has the following problems.

That is, when the printed circuit board is formed in a fine pattern in order to satisfy the demand that the printed circuit board is gradually miniaturized, as shown in FIG. 17, the distance L between the adjacent solder bumps 45 is gradually shortened. Then, when the bumps of the semiconductor chip and the bumps of the printed circuit board are bonded by thermocompression bonding, a bump bridge phenomenon, that is, a problem in which neighboring bumps are in contact with each other and is not insulated and causes a short defect, is caused. .

The present invention is to solve the above-mentioned problems of the prior art, an aspect of the present invention is to maintain a constant distance between the neighboring bumps to form a bump having a fine pitch and at the same time to prevent the bump bridge phenomenon printed circuit It is to provide a method of manufacturing a substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a printed circuit board, the method including: forming a plating resist having a bump forming opening on a substrate having an outer layer circuit, and performing a plating process on the bump forming opening to form a metal bump Forming a complex solder resist layer comprising a first solder resist covering the metal bumps and a second solder resist formed on the first solder resist and forming the second solder resist on the substrate. Removing to expose the metal bumps.

Here, the plating resist having the opening for forming bumps may include disposing a patterned mask on the plating resist and removing the plating resist corresponding to the opening for forming bumps using an exposure and development process. Can be formed.

The forming of the composite solder resist layer may be performed by a vacuum lamination process.

The first solder resist is a solder resist base film in contact with an upper surface of the substrate, the second solder resist is a solder resist cover film in contact with the solder resist base film, and the surface height of the solder resist base film is determined by the metal bumps from the substrate. It is preferably formed lower than the protruding height.

The removal of the second solder resist may be performed by a mechanical peeling process or a chemical peeling process.

The method may further include removing the plating resist after the forming of the metal bumps.

The method may further include forming a surface treatment layer on the upper surface of the metal bumps after exposing the metal bumps.

According to another aspect of the present invention, there is provided a method of manufacturing a printed circuit board, including forming a plating resist having an opening for forming bumps on a substrate having an outer layer circuit, and performing a plating process on the openings for forming bumps. Forming a solder resist layer covering the metal bumps on the substrate; and removing the solder resist layer to expose the metal bumps.

Here, the plating resist having the opening for forming bumps may include disposing a patterned mask on the plating resist and removing the plating resist corresponding to the opening for forming bumps using an exposure and development process. Can be formed.

The exposing the metal bumps may include disposing a mask on which the portions corresponding to the metal bumps are patterned on the formed solder resist layer, and removing the solder resists on the portions corresponding to the metal bumps using a laser. It may include a step.

In this case, the removal of the solder resist is preferably performed to a depth to expose the upper surface of the metal bump in the thickness direction by the area of the metal bump, the laser may include at least one of the CO ₂ laser or YAG laser. .

The method may further include removing the plating resist after the forming of the metal bumps.

The method may further include forming a surface treatment layer on the exposed upper surface of the metal bumps after exposing the metal bumps. The surface treatment layer may be formed to protrude from the solder resist layer.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to that, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may properly define the concept of the term in order to best explain its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

According to the present invention, a flip chip bump of a printed circuit board is formed of a metal bump using a plating process, thereby maintaining bumps between the bumps and forming bumps having a fine pitch.

In addition, the present invention has the effect of preventing the bump bridge phenomenon generated when mounting the semiconductor chip by using the thermal bonding by forming a metal bump instead of a low melting solder bump.

In addition, when the metal bumps are formed by the plating process, the manufacturing process may be performed in the form of a panel, thereby improving productivity.

1 to 8 are cross-sectional views illustrating a method of manufacturing a printed circuit board according to the first embodiment of the present invention.
9 to 11 are cross-sectional views illustrating a process of exposing metal bumps in a method of manufacturing a printed circuit board according to a second embodiment of the present invention.
12 to 17 are cross-sectional views sequentially illustrating a method of manufacturing flip chip bumps of a printed circuit board using a printing process according to the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS The objectives, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. It should be noted that, in the present specification, the reference numerals are added to the constituent elements of the drawings, and the same constituent elements are assigned the same number as much as possible even if they are displayed on different drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In this specification, terms such as first and second are used to distinguish one component from another component, and a component is not limited by the terms.

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

1 to 8 are cross-sectional views illustrating a method of manufacturing a printed circuit board according to the first embodiment of the present invention, and FIGS. 9 to 11 are metals in the method of manufacturing a printed circuit board according to the second embodiment of the present invention. Process sectional drawing which shows the step of exposing a bump.

Although the drawings omit schematically other detailed components of the printed circuit board except for the features of the embodiments, those skilled in the art are not particularly limited as long as all the printed circuit boards are known in the art and the manufacturing method according to the present invention may be applied. You will be able to fully recognize the presence.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

1st Example

First, as shown in FIG. 1, an insulating layer 110 is formed on a substrate 100 on which an inner layer circuit 101 is formed, and then an outer layer circuit 111 is formed.

In this embodiment, the inner layer circuit 101 is illustrated as being formed on one surface of the substrate 100, but may be formed on both sides, and the inner layer circuit may not be formed. In addition, although the insulating layer 110 and the outer layer circuit 111 are also illustrated as being formed on one surface of the substrate 100, it may be possible to be formed on both surfaces.

The substrate 100 may be a multilayer printed circuit board formed by stacking a plurality of insulating layers and a plurality of circuit layers.

In addition, a resin insulating layer may be used as the insulating layer 110. As the resin insulating layer, a thermosetting resin such as epoxy resin, a thermoplastic resin such as polyimide, or a resin impregnated with a reinforcing material such as glass fiber or an inorganic filler, for example, a prepreg may be used, and also a thermosetting resin. And / or photocurable resins may be used, but is not particularly limited thereto.

In addition, a circuit including the inner layer circuit 101 and the outer layer circuit 111 may be applied without limitation as long as it is used as a conductive metal for a circuit in the circuit board field, and copper is typically used in a printed circuit board.

Forming the outer layer circuit 111 on the insulating layer 110 generally processes a via hole (not shown) in the insulating layer 110 and then includes a seed layer (not shown) on the insulating layer 110 including the inner wall of the via hole. C), and a plating resist pattern (not shown) having an opening for forming an outer layer circuit 111 is formed on the seed layer.

Thereafter, a metal layer may be formed in the opening for forming the outer layer circuit 111 by performing a plating process, the plating resist pattern may be removed, and the exposed seed layer may be removed to form the outer layer circuit 111 as shown in FIG. 1. . Here, the seed layer and the metal layer may be formed by an electroless plating method and an electrolytic plating method, and the via hole processing and the plating resist pattern formation are well known techniques, and a detailed description thereof will be omitted.

Next, as shown in FIG. 2, the plating resist 120 is coated on the formed outer layer circuit 111.

In this case, the plating resist 120 may be a dry film as a photosensitive material, but is not particularly limited thereto.

Next, as shown in FIG. 3, the bump forming opening 120a is formed in the coated plating resist 120.

To form the bump forming opening 120a, a portion corresponding to a specific pattern, for example, the bump forming opening 120a may be formed in the plating resist 120 applied on the outer layer circuit 111, as shown in FIG. 2. Covered, except for the bump forming opening 120a is to place a mask (not shown) with an open pattern is formed, then performing an exposure process to harden the plating resist corresponding to the open portion of the mask, The separation process may be performed by removing the mask, and then removing the uncured portion, that is, the plating resist corresponding to the bump forming opening 120a by the development process, but is not limited thereto.

Next, as shown in FIG. 4, a metal bump 130 is formed by performing a plating process on the bump forming opening 120a, and then, as shown in FIG. 5, the plating resist 120 is removed.

In this case, the plating process for forming the metal bumps 130 may be an electrolytic plating or an electroless plating process. In addition, the plating process may be performed such that the surface height of the metal bump 130 is the same as the surface of the plating resist 120 or higher than the surface of the plating resist 120.

As such, instead of forming the solder bumps through the conventional printing process and the reflow process, the metal bumps 130 are formed by performing the plating process, thereby eliminating the flux and solder paste printing process, the reflow process, and the deflux process. As a result, the process can be simplified.

In addition, by forming the metal bumps 130 by the plating process, there is an advantage that it is easy to implement a fine pattern by maintaining a constant gap between the metal bumps 130 formed.

The metal bumps 130 are formed and then the plating resist 120 is removed. In this case, a mechanical peeling or a chemical peeling method may be used to remove the plating resist 120, but is not particularly limited thereto.

Next, as shown in FIG. 6, a complex resist layer 140 covering the outer circuit 111 and the metal bumps 130 is formed on the insulating layer 110 of the substrate 100.

In this case, the composite resist layer 140 may include a first solder resist 140a in contact with the upper surface of the insulating layer 110 and a second solder resist 140b in contact with the first solder resist 140a, but specifically It is not limited. That is, in the present invention, as shown in FIG. 6, two layers of solder resists are stacked in the composite resist layer 140, but three or more layers of solder resists may be stacked and used.

In the present invention, the first solder resist 140a in contact with the insulating layer 110 of the substrate 100 is called a solder resist base film, and the second solder resist 140b in contact with the first solder resist 140a is soldered. It is named a resist cover film.

As described above, both the solder resist base film 140a and the solder resist cover film 140b of the present invention may be both film materials or only the solder resist cover film 140b may be film materials, but are not particularly limited thereto. no.

In addition, the solder resist base film 140a and the solder resist cover film 140b may be different from each other, or may be the same kind, and are separated between the solder resist base film 140a and the solder resist cover film 140b. It may or may not include an adhesive layer.

In the first embodiment of the present invention, the composite resist layer 140 is formed on the insulating layer 110 using a vacuum lamination process as a film material. However, when the composite resist layer 140 is not a film material, another process is performed. To be formed on the insulating layer 110.

In this case, as shown in FIG. 6, the composite resist layer 140 is formed to cover the outer layer circuit 111 and the metal bumps 130, and the solder resist base film 140a in contact with the double insulating layer 110. The surface height of the metal bumps 130 is preferably formed to be lower than the height protruding from the outer circuit (111). That is, the metal bumps 130 are formed to partially protrude from the solder resist base film 140a.

Next, as shown in FIG. 7, the solder resist cover film 140b of the composite resist layer 140 is removed to expose the surface of the solder resist base film 140a and at the same time the metal bumps 130 are moved from the top surface in the thickness direction. To expose some.

That is, since the surface height of the solder resist base film 140a is formed lower than the surface height of the metal bumps 130, the solder resist is removed by removing the solder resist cover film 140b formed on the solder resist base film 140a. At the same time the base film 140a is exposed, a portion of the metal bumps 130 protruding from the solder resist base film 140a is exposed.

In this case, the removal of the solder resist cover film 140b may be performed by mechanical peeling or chemical peeling.

As such, by forming a part of the metal bumps 130 protruding from the solder resist base film 140a, there is an advantage in that the bonding force can be further improved when connecting to an external device.

In addition, according to the present embodiment, the metal bumps 130 are formed by forming a complex solder resist layer 140 on the formed metal bumps 130 and removing the solder resist cover film 140b. ) And the soldering resist base film 140a can be improved.

Next, as shown in FIG. 8, the surface treatment layer 150 is formed on the exposed upper surface of the metal bumps 130.

The surface treatment layer 150 is formed to prevent the oxidation of the metal bumps 130 and to increase the bonding force with the semiconductor chip bumps to be subsequently connected, but is not particularly limited if known in the art, for example, electrolytic gold plating (Electro Gold Plating), Immersion Gold Plating, Organic Solderability Preservative (OSP), or Immersion Tin Plating, Immersion Silver Plating, ENIG (Electroless Nickel and immersion gold); It may be formed by electroless nickel plating / substituting plating), DIG plating (Direct Immersion Gold Plating), hot air solder leveling (HASL), or the like.

Second Example

In the present embodiment, the content overlapping with the first embodiment will be omitted. That is, in this embodiment, the steps up to forming the metal bumps are the same as in the first embodiment, and thus, the drawings and descriptions for the processes up to the step of forming the metal bumps will be omitted and will be described later.

As shown in FIG. 9, the solder resist layer 240 covering the outer circuit 111 and the metal bumps 130 is formed on the substrate 100.

The solder resist layer 240 may be formed by applying a solder resist on the insulating layer 110. At this time, the solder resist is preferably applied so that the metal bump 130 is completely covered.

The solder resist may be an insulating photocurable resin, a mixture of a photocurable resin and a thermosetting resin, or a thermosetting resin, but is not particularly limited thereto.

In addition, a method of applying a solder resist on the insulating layer 110 of the substrate 100 generally includes screen printing, roll coating, curtain coating, and spray when the solder resist is ink. In the case of a film, there is a vacuum lamination method.

Next, as shown in FIG. 10, the solder resist layer 240 formed on the upper surface of the metal bumps 130 is removed to the depth where the upper surface of the metal bumps 130 is exposed in the thickness direction by the area of the metal bumps 130. To expose the top surface of the metal bumps 130.

In this case, the solder resist layer 240 may be removed to be wider than the area of the metal bumps 130, or the solder resist layer 240 may be exposed to a depth that exposes not only the top surface of the metal bumps 130 but also a part of a side surface connected to the top surface of the metal bumps 130. It is also possible to remove.

In the present invention, the solder resist is cured using a thermosetting resin, and then the top surface of the metal bumps 130 is exposed by selectively removing the cured solder resist using a laser drill according to a solder resist mask pattern. At this time, the laser drill is CO ₂ Laser drills or YAG laser drills and the like, but are not particularly limited thereto.

In this embodiment, after forming the metal bumps 130 as described above, the solder resist layer 240 is formed on the formed metal bumps 130, and the metal is removed by exposing only the upper surface of the metal bumps 130 with a laser. The surface of the bump 130 and the inner side surface of the solder resist layer 240 may be removed in a clean shape. At this time, the smaller the area removed by the laser can implement a cleaner surface and side shape.

However, a portion not selectively exposed to exposure by applying a photoresist or a solder resist which is a mixture of the photocurable resin and a thermosetting resin, then laminating a solder resist mask pattern, and using a photolithography method including an exposure and development process The process of exposing the metal bumps 130 by removing the solder resist will also be possible.

Next, as shown in FIG. 11, the surface treatment layer 250 is formed on the exposed upper surface of the metal bumps 130.

Since the method of forming the surface treatment layer 250 has been described in the first embodiment, it will be omitted here.

However, in this embodiment, by removing a portion of the solder resist in the thickness direction by the area of the metal bump 130 using a laser drill, as shown in Figure 10, the surface height of the exposed metal bump 130 is the solder resist layer Since the step height is slightly lower than the surface height of the 240, the growth thickness is adjusted when the surface treatment layer 250 is formed, and as shown in FIG. 11, the surface of the surface treatment layer 250 protrudes from the solder resist layer 240. In other words, the surface height of the surface treatment layer 250 is preferably formed to be higher than the surface height of the solder resist layer 240.

As such, by adjusting the formation height of the surface treatment layer 250 so that the surface treatment layer 250 protrudes from the solder resist layer 240, there is an advantage in that the bonding force can be further improved when connecting to an external device. .

In addition, since the present embodiment forms the metal bumps 130 and then forms the solder resist layer 240 on the formed metal bumps 130, the adhesion between the metal bumps 130 and the solder resist layer 240 may be improved. Can be.

Although the present invention has been described in detail through specific embodiments, this is for explaining the present invention in detail, and the method of manufacturing a printed circuit board according to the present invention is not limited thereto, and it is common in the art within the technical spirit of the present invention. It is obvious that modifications and improvements are possible by those skilled in the art.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: substrate 101: inner layer circuit
110: insulating layer 111: outer circuit
120: plating resist 120a: opening for bump formation
130: metal bump 140: composite solder resist layer
140a: solder resist base film 140b: solder resist cover film
150, 250: surface treatment layer 240: solder resist layer

Claims (16)

Forming a plating resist having a bump forming opening formed on a substrate having an outer layer circuit;
Forming a metal bump by performing a plating process on the bump forming opening;
Forming a complex solder resist layer including a first solder resist covering the metal bumps on the substrate and a second solder resist formed on the first solder resist; And
Removing the second solder resist to expose the metal bumps
And a step of forming the printed circuit board. The method according to claim 1,
The plating resist in which the opening for bump formation is formed,
Disposing a patterned mask on the plating resist; And
Removing the plating resist corresponding to the opening for forming bumps using an exposure and development process
Method of manufacturing a printed circuit board comprising a. The method according to claim 1,
Forming the composite solder resist layer is performed by a vacuum lamination process. The method according to claim 1,
And the first solder resist is a solder resist base film in contact with an upper surface of the substrate, and the second solder resist is a solder resist cover film in contact with the solder resist base film. The method of claim 4,
And a surface height of the solder resist base film is lower than a height at which the metal bumps protrude from the substrate. The method according to claim 1,
The removal of the second solder resist is a method of manufacturing a printed circuit board performed by a mechanical peeling process or a chemical peeling process. The method according to claim 1,
After forming the metal bumps,
The method of manufacturing a printed circuit board further comprising the step of removing the plating resist. The method according to claim 1,
After exposing the metal bumps,
The method of claim 1, further comprising forming a surface treatment layer on the upper surface of the metal bumps. Forming a plating resist having a bump forming opening formed on a substrate having an outer layer circuit;
Forming a metal bump by performing a plating process on the bump forming opening;
Forming a solder resist layer covering the metal bumps on the substrate; And
Removing the solder resist layer to expose the metal bumps
And a step of forming the printed circuit board. The method according to claim 9,
The plating resist in which the opening for bump formation is formed,
Disposing a patterned mask on the plating resist; And
Removing the plating resist corresponding to the opening for forming bumps using an exposure and development process
Method of manufacturing a printed circuit board comprising a. The method according to claim 9,
Exposing the metal bumps,
Disposing a mask on which the portion corresponding to the metal bump is patterned on the formed solder resist layer; And
Removing solder resist of a portion corresponding to the metal bumps using a laser;
And a step of forming the printed circuit board. The method of claim 11,
And removing the solder resist to a depth at which the upper surface of the metal bump is exposed in the thickness direction by the area of the metal bump. The method of claim 11,
The laser is a method of manufacturing a printed circuit board comprising at least one of a CO ₂ laser or YAG laser. The method according to claim 9,
After forming the metal bumps,
The method of manufacturing a printed circuit board further comprising the step of removing the plating resist. The method according to claim 9,
After exposing the metal bumps,
And forming a surface treatment layer on the exposed upper surface of the metal bumps. The method according to claim 15,
And the surface treatment layer is formed to protrude from the solder resist layer.

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