KR20090099129A - The printed circuit board for flipchip package having copper bump with triangular profile and manufacturing method thereof - Google Patents

Abstract

A PCB for mounting a flip-chip and a manufacturing method thereof are provided to reduce a manufacturing cost by forming a bonding bump through an etching and plating process. A substrate comprises an insulation layer and a copper foil layer. The substrate is drilled for interfacial connection(S1). First copper plating is performed on the copper foil layer of the substrate(S2). A first etching resist is formed on the copper foil layer of the substrate. A circuit pattern is formed by a first etching(S3). The first etching resist is removed from the copper foil layer of the substrate. A second etching resist is formed on the copper foil layer of the substrate in order to expose an electrode part for connecting a flip chip. A bottom side of the electrode part for connecting the flip chip is formed with a triangle shape by a second etching(S4). Second copper plating is performed on the electrode part for connecting the flip chip(S5). The second etching resist is removed from the copper foil layer of the substrate. Ni/Au plating is performed on the electrode part for connecting the flip chip(S6).

Description

The printed circuit board for flip chip package having copper bump with triangular profile and manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flip chip mounting printed circuit board using a copper bump having a triangular cross section so as to form a bonding bump using only etching and plating processes generally used in a printed circuit board, and a method of manufacturing the same.

As the electronics industry has become lighter, smaller, faster, more versatile, and higher in performance, there is a demand for a technology for manufacturing a product having higher reliability at a lower cost. One of the important technologies for enabling the realization of such requirements is the packaging technology. With high performance and high speed of semiconductor chips, semiconductor chip packages have evolved from thin small outline packages (TSOPs) to flip chip technologies via ball grid arrays (BGAs) or chip size packages (CSPs). Among them, the CSP technology can reduce the size of the package to the level of the chip size and maintain the characteristics of the bare chip in the package state, thereby enabling mobile communication, digital video casing (DVC), and personal computer (PC). It is actively applied to cards and personal digital assistants (PDAs). However, when the wire bonding method is used, the high frequency characteristic is degraded due to the electrical delay due to the inductance, the resistance, and the capacitance of the wire, and there is a limit in the heat transfer characteristic.

Flip chip technology inverts the chip through a connection method using various materials and methods so that the pad of the chip faces the substrate, and then electrically and mechanically connects the chip and the substrate. The goal of packaging technology development is to achieve low cost, increase packaging density, and improve performance while maintaining circuit reliability.Furthermore, the use of flip chip processing when attaching a semiconductor chip to a circuit board can prevent chip contact. The ideal size is achieved because no separate area is required. Since the flip chip minimizes the connection length, performance in a high frequency environment is superior to other interconnection methods, and the number of connection terminals is reduced, thereby improving reliability with packaged components. In flip chip coupling, there is only one connection step between the chip and the circuit board. While wire bonding performs bonding one at a time, flip chip technology can potentially be implemented at lower cost than wire bonding because all connection bonding is done at the same time.

According to a conventional packaging technology using flip chip technology in a chip assembly step, a method of bonding a chip and a substrate by a conductive paste using Au bumps and then underfilling the chip and the substrate with a resin composition, solder balls After bonding a chip and a board | substrate using a (Solder Ball), the method of underfilling with a resin composition, the method of using wire bonding, etc. are known. Among them, the method using the solder ball has the advantage of bonding the chip and the substrate without applying excessive pressure, while the bumps have a metallic reaction, there is a disadvantage that must be heated to a high temperature above the melting point of the bump material. In addition, the manufacturing process is complicated and takes a lot of manufacturing cost and time, work is carried out in a separate process of the chip manufacturing process, and when the operating frequency is high, there is a problem such as poor performance.

The method of using Au bumps is a physical contact without a metallic reaction. Due to the excellent ductility and malleability of Au, the tip of the bump is easily deformed by pressing, so that the contact with the electrode on the substrate is easily performed. . In addition, it is possible to optimize the height of the bumps according to the required frequency characteristics. However, there is a problem that the waste of the material is so severe that the unit cost of the product rises.

A method using wire bonding, also known as stud bump bonding, uses wire bonders to form gold or solder wire ball bonds on I / O pads. A slightly modified wire bonder is used to attach the wire to the bond pad, the wire being cut near the stud. Stud bumping has the advantage that the initial investment is cheap and the bumping price is low because no UBM process is required, but Daffin has a problem that it is not economical because the process time is long.

In order to solve the above problems, the present invention uses only etching and plating processes generally used in printed circuit boards, so that flip chip bonding is formed using copper bumps having a triangular cross section. It is an object to provide that a substrate for flip chip mounting can be manufactured at a cost.

Another object of the present invention is to provide a manufacturing method capable of producing a large amount of flip chip mounting substrate.

In the present invention as a means for solving the above object, in a flip chip mounting printed circuit board,

A printed circuit board having circuit patterns formed of copper foil layers on both surfaces of the insulating layer (1);

An electrode (2) formed on the printed circuit board and having a vertical cross section in a triangular shape, the bottom side of which is in contact with the insulating layer;

Ni / Au plating layer (3) formed on the surface of the electrode; characterized in that it comprises a.

In addition, the electrode 2 is characterized in that made of copper (Copper) material.

In addition, in the method of manufacturing a printed circuit board for flip chip mounting,

Preparing a substrate having copper foil layers formed on both surfaces of the insulating layer, and performing a drill process for interlayer conduction;

Performing a first copper plating process on the entire copper foil layer on the substrate in the first step;

Forming a circuit pattern by first etching by forming a first etching resist having a circuit pattern on the copper foil layer of the second step;

After removing the first etching resist formed in step 3 and forming a second etching resist to expose the electrode portion for flip chip connection, the shape of the vertical cross section of the electrode portion is a triangle contacting the insulating layer at the base side. Performing an additional second etch on the electrode portion;

A fifth step of additional second copper plating on the electrode part after the fourth step;

And after step 5, removing the second etching resist, performing Ni plating on the flip chip connection electrode, and performing Au plating.

In addition, the drill step of the first step is characterized in that for processing by selecting any one of a mechanical drill for drilling through holes using the drill bit or a laser to form a via hole.

In addition, the first and second etching resist using a photosensitive resist such as a liquid photoresist (LPR) or a dry film resist (DFR),

In the fifth step, the electrode portion is characterized in that the height is 30 ~ 80㎛.

The present invention is to replace the conventional flip chip bonding method by solder bumps or metal bumps, and since the flip chip bonding is formed using copper bumps having a triangular cross section, etching and etching generally used in a printed circuit board By allowing the bonding bumps to be formed using only the plating process, there is an effect of improving lower cost and productivity.

Hereinafter, with reference to the accompanying drawings in order to explain the present invention in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

1 is a flip chip mounting printed circuit board using a copper bump having a triangular cross section according to the present invention.

Referring to the structure of the printed circuit board as shown in FIG.

In the printed circuit board, circuit patterns formed of copper foil layers are formed on both surfaces of the insulating layer 1. A copper electrode 2 is formed on the printed circuit board so that an electrode on the substrate is in contact with the insulating layer at the bottom of the vertical cross section, wherein the electrode 2 is formed in the form of a triangle. Ni / Au plating layer 3 is formed on the surface of the electrode 2 to have good electrical characteristics when connected to the chip pad.

2 is a flowchart of a method for manufacturing a flip chip mounting printed circuit board using a copper bump having a triangular cross section according to the present invention, and FIG. 3 is a flowchart of FIG. 2.

The board | substrate with which the copper foil layer is formed in both surfaces of the insulating layer 1 is prepared, and it drills for interlayer conduction (S1). In the above drill processing method, a mechanical drill processing method using a drill bit is mainly used when processing a through hole, and a drilling method using a laser, a hole having a fine diameter or a via hole having one side closed. (Blind Via Hole) is used to form the drill or laser processing method is used.

Subsequently, the first copper plating is applied to the entire copper foil layer on the drilled substrate (S2). Copper plating is electrolytic copper plating after the electroless copper plating is carried out, but the current is not flowing in the hole immediately after the drilling process, so the first electroless copper plating is performed so that the epoxy portion in the hole is coated with a fine copper foil on the surface thereof. To enable subsequent electrolytic copper plating. At this time, copper plating is formed to a thickness of about 10 ~ 40㎛, the thickness of the copper foil of the surface layer by copper plating increases its thickness, and the copper foil layer for interlayer connection is formed in the hole.

A first etching resist 4 having a circuit pattern is formed on the copper plated copper foil layer to form a circuit pattern by first etching (S3). A method of forming a circuit pattern on the printed circuit board includes a printing method, a photolithography method, and the like. In the case of a printed circuit board requiring a fine pattern, a method of forming a pattern by the photolithography method is mainly used.

Therefore, a photosensitive resist such as a liquid phosphor (istry phosphorusist) or a dry film resist (DFR) is coated on the copper foil layer, and the resist remains at a position where a circuit pattern is to be formed by exposure and development. After removing the unnecessary copper foil portion not covered with the resist with a highly corrosive chemical to form a circuit pattern, the remaining resist is peeled off.

Thus, the first etching resist 4 on the substrate on which the circuit pattern is formed is removed, and the second etching resist 5 is formed so that the flip chip connection electrode 2 portion is exposed, and then the vertical portion of the electrode 2 portion is vertical. An additional second etching is performed on the portion of the electrode 2 so that the shape of the cross section is a triangle contacting the insulating layer 1 (S4).

The reason why the second electrode is additionally etched in the form of a triangle is that a modified semi additive process (MSAP) or a semi additive process (SAP) method is used to implement a fine pattern product having a pitch of 70 pitch or less. When the 70 pitch is realized by configuring the electrode 2 in the form of a triangle, it is possible to produce a product using the same process as before, and does not perform a conventional SOP (Solder On Pad) process and directly mounts the chip. This is possible.

That is, as described above, the second etching resist 5 is coated to exfoliate the first etching resist 4 remaining after forming the circuit pattern and to expose the portion for etching only the electrode 2 portion. Exposure and development. Here, as in the first etching resist 4, an additional second etching is performed after the formation of the second etching resist 5 by using a photosensitive resist such as a liquid phosphor (LPR) or a dry film resist (DFR). The exposed electrode 2 for mounting is triangular in cross section in the shape of the upper edge formed by over etching, and the lower side of the triangular cross section comes into contact with the insulating layer 1.

The second copper plating is additionally performed to have a height of 30 to 80 μm on the portion of the electrode 2 having a triangular cross section by the second etching (S5). Here, the second etching resist 5 formed in the above (S4) remains without peeling and functions as a plating resist. The second copper plating is performed only on the electrode portion which is not covered with the resist, and the copper plating layer is formed up to the height of 30 to 80 μm so as to allow connection with the chip.

After the second etching resist 5 on the substrate on which the electrode 2 having a height of 30 to 80 μm is formed by the second copper plating, Ni plating is performed on the flip chip connection electrode part, followed by Au plating (3). A printed circuit board for flip chip mounting using a copper bump having a triangular cross section (S6) is manufactured.

As described above, preferred embodiments according to the present invention have been described, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the scope of the present invention as claimed in the following claims. Anyone with knowledge of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

1 is a flip chip mounting printed circuit board using a copper bump having a triangular cross section according to the present invention.

2 is a flow chart of a method for manufacturing a flip chip mounting printed circuit board using a copper bump having a triangular cross section according to the present invention.

3 is a process chart of a method for manufacturing a flip chip mounting printed circuit board using a copper bump having a triangular cross section according to the present invention.

** Main Names of Drawings **

1: insulating layer 2: electrode

3: Ni / Au plating layer

Claims (6)

In the printed circuit board for flip chip mounting, A printed circuit board having circuit patterns formed of copper foil layers on both surfaces of the insulating layer (1); An electrode (2) formed on the printed circuit board and having a vertical cross section formed in a triangular shape, the bottom side of which is in contact with the insulating layer; Ni / Au plating layer (3) formed on the surface of the electrode; flip-chip printed circuit board using a copper bump having a triangular cross section. The method of claim 1 The electrode (2) is a flip chip mounting printed circuit board using a copper bump having a triangular cross section, characterized in that the copper (Copper) material. In the manufacturing method of a printed circuit board for flip chip mounting, Preparing a substrate having copper foil layers formed on both surfaces of the insulating layer, and performing drill processing for interlayer conduction; Performing a first copper plating process on the entire copper foil layer on the substrate in the first step; Forming a circuit pattern by first etching by forming a first etching resist having a circuit pattern on the copper foil layer of the second step; After removing the first etching resist formed in step 3 and forming a second etching resist to expose the electrode portion for flip chip connection, the shape of the vertical cross section of the electrode portion is a triangle contacting the insulating layer at the base side. Performing an additional second etch on the electrode portion; A fifth step of additional second copper plating on the electrode part after the fourth step; After step 5, removing the second etching resist, performing Ni plating on the flip chip connection electrode part, and then performing Au plating; and using a copper bump having a triangular cross section, comprising: Method of manufacturing a printed circuit board for chip mounting. The method of claim 3, wherein The drill processing of the first step is a flip chip mounting printing using a copper bump having a triangular cross section, characterized in that for processing by selecting any one of a mechanical drill for processing through holes using a drill bit or a laser forming a via hole. Method of manufacturing a circuit board. The method of claim 3, wherein The first and second etching resist is a photosensitive resist such as LPR (Liquid Photoresist) or DFR (Dry Film Resist) is a method of manufacturing a flip chip mounting printed circuit board using a copper bump having a triangular cross-section. . The method of claim 3, wherein And the electrode portion has a height of 30 to 80 µm in the fifth step. A method of manufacturing a flip chip mounting printed circuit board using a copper bump having a triangular cross section.

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