KR20120113633A - The printed circuit board and the method for manufacturing the same - Google Patents

Abstract

PURPOSE: A printed circuit board and a manufacturing method thereof are provided to improve a solder bonding property by plating the upper side of a nickel layer with a copper thin film to increasing the content of copper. CONSTITUTION: A circuit pattern(124) is formed on an insulation plate(110). A pad(122) is connected to the circuit pattern. A first metal layer(130) with nickel is formed on the circuit pattern. A second metal layer(140) with copper is formed on the first metal layer. A third metal layer(150) with silver is formed on the second metal layer.

Description

[0001] The present invention relates to a printed circuit board and a method of manufacturing the same,

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

The circuit board includes a circuit pattern on an electrically insulating substrate, and is a substrate for mounting electronic components or the like.

In the manufacture of such printed circuit boards, various surface treatment techniques have been used to form solderable and bondable layers on soldering and adhesive pads.

In general, electrolytic nickel / gold surface treatments have been mainly used, but recently, nickel / palladium / gold surface treatments having great advantages in terms of design freedom and price have been in the spotlight.

Looking at each plated layer for the surface treatment, a nickel-phosphorus alloy layer, a palladium-phosphorus alloy layer is mainly used, the phosphorus content in the nickel plated layer is generally about 6-8%.

At this time, the characteristics of the nickel plating layer is changed according to the phosphorus content contained in the nickel plating layer, and in general, as the phosphorus content is increased, the crystalline structure is changed into an amorphous structure.

In addition, when the phosphorus content is increased, corrosion resistance of the nickel plating layer may be excellent, thereby preventing erosion that may occur from the existing substitution gold plating process. The electroless nickel / palladium / gold plating process has been developed to suppress such erosion (commonly called black pad phenomenon). In this process, the subsequent nickel plating process is performed by a reduction reaction rather than a substitution reaction. Erosion does not occur.

In the case of the printed circuit board using the electroless nickel / palladium / gold plating layer, it has the advantage of obtaining excellent solder bonding properties and wire bonding properties even at a low gold plating thickness, and thus it is applied to package products requiring high reliability. It is becoming.

However, as the type of solder is diversified, different reactions occur between each solder and the plating layer, and thus, solder joint characteristics of each solder type are different. In this case, when the solder type having a small content of Cu is used, the P-rich layer is thick, which causes a problem in that solder bonding properties are inferior.

The embodiment provides a new printed circuit board and a method of manufacturing the same.

The embodiment provides a printed circuit board having good solder adhesion and a method of manufacturing the same.

Technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above are clearly understood by those skilled in the art to which the embodiments proposed from the following description belong. Could be.

A printed circuit board according to an embodiment of the present invention includes an insulating layer, a circuit pattern or pad formed on the insulating layer, a first metal layer formed on the circuit pattern or pad, and including nickel, and the first And a second metal layer formed on the metal layer, the second metal layer containing copper, and a third metal layer formed on the second metal layer and containing silver.

A method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention includes preparing an insulating substrate, forming a circuit pattern or a pad on the insulating substrate, and forming a first metal layer including nickel on the circuit pattern or the pad. Forming a second metal layer including copper on the first metal layer, and forming a third metal layer including silver on the second metal layer.

According to the embodiment of the present invention, by performing a copper thin film plating on the top of the nickel layer to increase the content of copper, there is an effect that can improve the solder joint characteristics by reducing the nickel consumption.

1 is a cross-sectional view of a printed circuit board according to a first embodiment of the present invention.
2 to 6 are cross-sectional views illustrating a first method for manufacturing the printed circuit board of FIG. 1.
7 to 10 are cross-sectional views illustrating a second method for manufacturing the printed circuit board of FIG. 1.
11 is a cross-sectional view of a printed circuit board according to a second exemplary embodiment of the present invention.
12 to 18 are cross-sectional views illustrating a method for manufacturing the printed circuit board of FIG. 11.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

In order to clearly illustrate the present invention in the drawings, thicknesses are enlarged in order to clearly illustrate various layers and regions, and parts not related to the description are omitted, and like parts are denoted by similar reference numerals throughout the specification .

When a portion of a layer, film, region, plate, etc. is said to be "on top" of another part, this includes not only when the other part is "right over" but also when there is another part in the middle. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

Referring to FIG. 1, a printed circuit board 100 according to a first embodiment of the present invention may include an insulation plate 110 and a base pad 122 connected to a circuit pattern 124 formed on the insulation plate 110. ) And a protective layer 160 covering the circuit pattern 124.

The insulating plate 110 may be a supporting substrate of a printed circuit board on which a single circuit pattern is formed, but may also mean an insulating layer region in which one circuit pattern 124 is formed among printed circuit boards having a plurality of stacked structures. have.

When the insulating plate 110 means one insulating layer among a plurality of stacked structures, a plurality of circuit patterns 124 may be continuously formed on the upper or lower portion of the insulating plate 110.

The insulation plate 110 may be a thermosetting or thermoplastic polymer substrate, a ceramic substrate, an organic-inorganic composite material substrate, or a glass fiber impregnated substrate. When the insulation plate 110 includes a polymer resin, the insulation plate 110 may include an epoxy-based insulation resin. It may alternatively include polyimide resin.

A plurality of base pads 122 connected to the plurality of circuit patterns 124 are formed on the insulating plate 110. The base pad 122 is a bump for mounting a device mounted on the printed circuit board 100 and refers to a base pad 122 to which solder (not shown) is attached or wire bonded.

The circuit pattern 124 and the base pad 122 may be formed of a conductive material, and may be formed by patterning a copper foil layer formed on the insulating plate 110. Therefore, the circuit pattern 124 and the base pad 122 may be formed of an alloy including copper, and roughness may be formed on a surface thereof.

The first metal layer 130 is formed on the top and side surfaces of the circuit pattern 124 and the base pad 122.

The first metal layer 130 is a nickel alloy layer containing nickel (Ni). In this case, roughness may be formed on the surface of the first metal layer 130.

The first metal layer 130 is formed of an alloy containing nickel, which may include a predetermined amount of P (phosphorus).

In this case, the phosphorus contained in the first metal layer 130 is a medium type or a low phosphorus type, which satisfies the range of 6 to 13 wt%, or satisfies the range of 1 to 6 wt% in the first metal layer 130. Can have

Roughness may be formed on the surface of the first metal layer 130 similarly to the base pad 122.

In addition, the first metal layer has a thickness satisfying 0.1 to 5 μm and is formed on the base pad 122 or the circuit pattern 124.

The second metal layer 140 is formed to surround the top and side surfaces of the first metal layer 130.

The second metal layer 140 is a thin film layer formed of an alloy containing copper.

Roughness may be formed on the surface of the second metal layer 140 similarly to the first metal layer 130.

In addition, the second metal layer 140 has a thickness satisfying 10 to 100 nm and is formed on the first metal layer 130.

The third metal layer 150 is formed on the second metal layer 140 to surround the top and side surfaces of the second metal layer 140.

In this case, the third metal layer 150 is formed of an alloy containing silver.

The third metal layer 150 has a thickness that satisfies 0.1 to 5㎛, and is formed to surround the top and side surfaces of the second metal layer 140.

The stacked structure of the circuit pattern 124, the first metal layer 130, the second metal layer 140, and the third metal layer 150 on the circuit pattern 124 constitutes a metal circuit pattern, and a base pad A stack structure of the first metal layer 130, the second metal layer 140, and the third metal layer 150 is formed on the base pad 122.

A protective layer 160 is formed on the insulating plate 110 to cover the circuit pattern 124.

The protective layer 160 is to protect the surface of the insulating plate 110 and is formed on the front surface of the insulating plate 110, and the upper surface of the base pad 122 stacked structure to be exposed, that is, the third metal layer 150. It has an opening 162 that opens.

Solder is formed or wires are bonded to the third metal layer 150 of the exposed base pad 122.

As described above, in the embodiment of the present invention, the surface treatment of the printed circuit board 100 is performed by forming the second metal layer 140 between the first metal layer 130 and the third metal layer 150. To increase the reliability.

That is, in general, the third metal layer 150 may be directly plated in the case of copper and brass, but the plating adhesion is not good for iron, nickel, and tin, and the pretreatment process is required. In addition, in the case of the third metal layer 150, since the enthusiasm characteristic is weak and the reliability characteristic is lowered, there is a need to introduce a barrier layer on the lower surface to improve the problem.

In this case, when the third metal layer 150 is formed on the top of the first metal layer 130, the silver in the silver plating solution is partially substituted to reduce the safety of the plating solution, and thus the silver plating film is non-uniformly formed.

Therefore, in the embodiment according to the present invention, the second metal layer 140 is formed between the first metal layer 130 and the third metal layer 150 to increase the adhesion of the third metal layer 150.

That is, by forming the second metal layer 140 between the first metal layer 130 and the third metal layer 150, the adhesion of the silver plated film is improved, and even if a low copper content solder ball is applied, Similar performance can be achieved with solder joints.

On the other hand, when the thickness of the second metal layer 140 is 200nm or more, since the copper component is diffused into the third metal layer 150 by heat treatment, the first metal layer 130 may not act as a barrier, and thus, the second metal layer The thickness of 140 is to satisfy the range of 10 to 100 nm.

Hereinafter, a method of manufacturing the printed circuit board 100 of FIG. 1 will be described with reference to FIGS. 2 to 10.

2 to 6 are cross-sectional views illustrating a first method for manufacturing the printed circuit board of FIG. 1.

First, as illustrated in FIG. 2, the conductive layer 120 is stacked on the insulating plate 110. In this case, when the insulating plate 110 is an insulating layer, the laminated structure of the insulating layer and the conductive layer 120 may be a conventional copper clad laminate (CCL).

In the stacked structure of the insulating plate 110 and the conductive layer 120, the conductive layer 120 is etched to form the base pad 122 and the circuit pattern 124 of FIG. 3.

Next, the first metal layer 130 of FIG. 4 is formed by electroplating the patterned base pad 122 and the circuit pattern 124 with the seed layer.

The first metal layer 130 may be formed of an alloy of nickel and P (phosphorus), and is formed so as not to exceed a predetermined thickness by controlling a voltage.

In this case, the plating liquid used to form the first metal layer 130 is formed by mixing nickel and phosphorus, and the phosphorus may be any one of a low phosphorus and a phosphorus type. In other words, the content of the phosphorus contained in the plating solution is to satisfy 1 to 13% by weight.

At this time, the first metal layer 130 has a thickness that satisfies 0.1 to 5㎛.

In addition, roughness may be applied to the circuit pattern 124 and the base pad 122 so as to smoothly perform plating, and roughening may be performed by roughening copper to the seed layer using the circuit pattern 124 and the base pad 122. It can be performed by plating.

In addition, the first metal layer 130 may be formed to the top and side surfaces of the circuit pattern 124 and the base pad 122 by electroplating the circuit pattern 124 and the base pad 122 with a seed layer.

Next, as shown in FIG. 5, the second metal layer 140 is formed by electroplating the first metal layer 130 with the seed layer.

The second metal layer 140 may be formed of an alloy including copper, and may be formed to surround the top and side surfaces of the first metal layer 130.

In this case, the second metal layer 140 has a thickness that satisfies 10 to 100nm. That is, when the thickness of the second metal layer 140 exceeds 200 nm, the copper component diffuses to the upper layer due to the heat treatment, thereby lowering the reliability of the printed circuit board 100. It is formed to a thickness so as to satisfy to 100nm.

In addition, roughness may be applied to a surface of the first metal layer 130 so that the second metal layer 140 may be smoothly plated. Similarly, the second metal layer 140 may be smoothly plated with the third metal layer 150. Roughness may be imparted to the surface to make it possible.

Next, as shown in FIG. 6, a third metal layer 150 is formed on the second metal layer 140. In this case, the third metal layer 150 may be formed of an alloy containing silver, and may be formed by electroless plating.

The third metal layer 150 may also be formed to surround the top and side surfaces of the second metal layer 140.

Next, as shown in FIG. 1, the printed circuit board 100 of FIG. 1 is formed by applying the protective layer 160 to have an opening 162 that opens the pad structure while filling the circuit pattern 124.

Meanwhile, the printed circuit board 100 of FIG. 1 may be manufactured through electroless plating.

7 to 10 are cross-sectional views illustrating a second method for manufacturing the printed circuit board of FIG. 1.

First, as shown in FIG. 7, the patterned circuit pattern 124 and the base pad 122 are formed on the insulating plate 110, and then electroless plating is performed to form a first surface on the front of the insulating plate 110. The plating layer 132 is formed.

In this case, roughness may be imparted to the surface of the insulating plate 110 by performing a desmear process for removing the smear of the insulating plate 110.

The first plating layer 132 formed by performing electroless plating may be formed of an alloy of nickel and P (phosphorus).

Next, electroless plating is performed as shown in FIG. 8 to form a second plating layer 142 on the first plating layer 132.

The second plating layer 142 formed by performing electroless plating may be formed of an alloy including copper.

In this case, it is preferable that the first plating layer 132 has a thickness satisfying 0.1 to 5 μm, and the second plating layer 142 has a thickness satisfying 10 to 100 nm.

Next, electroless plating is performed as shown in FIG. 9 to form a third plating layer 152 on the second plating layer 142.

The third plating layer 155 may be formed of an alloy containing silver having a thickness satisfying 0.1 to 5 μm.

Finally, the circuit patterns 124 and the base pad 122 are etched by etching the first to third plating layers 132, 142, and 152 so that only the area covering the circuit pattern 124 and the base pad 122 remains. The first metal layer 130 etched from the first plating layer 132, the second metal layer 140 etched from the second plating layer 142, and the third metal layer 150 etched from the third plating layer 152 are formed thereon. do.

In this case, in the case of the printed circuit board 100 formed by electroless plating, the first metal layer 130 may be formed to surround side surfaces of the base pad 122 and the circuit pattern 124. ) And the third metal layer 150 are formed only on the upper surface of the first metal layer 130, and thus have a configuration different from that of the printed circuit board 100 of FIG. 1.

Hereinafter, a printed circuit board according to a second exemplary embodiment of the present invention will be described with reference to FIGS. 11 to 18.

11 is a cross-sectional view of a printed circuit board according to a second exemplary embodiment of the present invention.

Referring to FIG. 11, a printed circuit board 200 according to a second embodiment of the present invention may include an insulation plate 210 and a base pad 222 connected to a circuit pattern 224 formed on the insulation plate 210. ) And a protective layer 260 covering the circuit pattern.

The insulation plate 210 may be a thermosetting or thermoplastic polymer substrate, a ceramic substrate, an organic-inorganic composite material substrate, or a glass fiber impregnated substrate. When the insulation plate 210 includes a polymer resin, the insulation plate 210 may include an epoxy-based insulation resin. It may alternatively include polyimide resin.

A plurality of base pads 222 connected to the plurality of circuit patterns 224 are formed on the insulating plate 210. The base pad 222 is a bump for mounting a device mounted on the printed circuit board 200 and refers to a base pad 222 to which solder (not shown) is attached or wire bonded.

The circuit pattern 224 and the base pad 222 may be formed of a conductive material, and may be formed by simultaneously patterning a copper foil layer formed on the insulating plate 110, and may be formed of an alloy including copper.

The first metal layer 230 is formed on the top and side surfaces of the circuit pattern 224 and the base pad 222. The first metal layer 230 may be formed of an alloy of nickel and P (phosphorus).

A protective layer 260 is formed on the insulating plate 210 to cover the circuit pattern 224.

The protective layer 260 is to protect the surface of the insulating plate 210 and is formed on the front surface of the insulating plate 210, and opens the first metal layer 230 and the upper surface of the base pad 222 stacked structure to be exposed. It has an opening 262 to be.

The second metal layer 240 is formed on the first metal layer 230 of the exposed base pad 220. The second metal layer 240 may be formed of an alloy including copper.

In addition, a third metal layer 250 is formed on the second metal layer 240. The third metal layer 250 is formed of an alloy containing silver.

In this case, the first metal layer 230 has a thickness of 0.1 to 5㎛, the second metal layer 240 has a thickness of 10 to 100nm, the third metal layer 250 is 0.1 to It is formed with a thickness that meets 5 μm.

In addition, the second and third metal layers 240 and 250 may be formed to surround side surfaces of the opening 262 of the protective layer 260.

As described above, unlike the printed circuit board 100 of FIG. 1, the printed circuit board 200 of FIG. 11 has the second and third metal layers 240 and 250 formed only in the pad structure to form the openings of the protective layer 260. 262) has a structure extending to the side.

In addition, the first to third metal layers 230, 240 and 250 are formed only on the base pad 222 so that the first to third metal layers 230, 240 and 250 extend to the side surface of the opening 262. May be

Solder may be formed on the third metal layer 250 of the exposed base pad 220 or may be attached to the device by performing wire bonding.

12 to 18 are cross-sectional views illustrating a method for manufacturing the printed circuit board of FIG. 11.

First, as illustrated in FIG. 12, when the conductive layer is stacked on the insulating plate 210, and the insulating plate 210 is an insulating layer, the laminated structure of the insulating layer and the conductive layer may be a conventional copper clad laminate (CCL).

The conductive layer is etched in the stacked structure of the insulating plate 210 and the conductive layer to form the base pad 222 and the circuit pattern 224 of FIG. 12.

Next, as shown in FIG. 13, the first plating layer 232 is formed by performing electroless plating on the patterned base pad 222 and the circuit pattern 224.

In this case, the first plating layer 235 is an alloy layer containing nickel and phosphorous.

In this case, roughness may be applied to the insulating plate 210, the circuit pattern 224, and the base pad 222 to facilitate the formation of the first plating layer 232.

Next, as shown in FIG. 14, the first plating layer 232 is etched to form the first metal layer 230.

In this case, the first metal layer 230 may be etched with a width greater than that of the circuit pattern 224 and the base pad 222 so as to surround side surfaces of the circuit pattern 224 and the base pad 222.

Next, as shown in FIG. 15, the protective layer 260 is coated to have an opening 262 that opens the first metal layer 230 on the base pad 222 while filling the circuit pattern 224.

Next, a mask 270 is formed on the protective layer 260 as shown in FIG. 16.

The mask 270 may include a window 272 that opens the opening 262 of the solder resist 260, and may be formed of a photoresist or a dry film.

In this case, the width of the window 272 may be greater than the width of the opening 262 of the protective layer 260.

Next, plating is performed on the first metal layer 230 exposed to the window 272 to form the second metal layer 240 as shown in FIG. 17.

In this case, before forming the second metal layer 240, the desmear process may be performed to provide roughness to a part of the side surface and the upper surface of the opening 262 of the protective layer 260.

The second metal layer 240 may be formed of an alloy including copper.

Next, as shown in FIG. 18, the third metal layer 250 is formed by plating on the second metal layer 240 exposed through the window 272.

In this case, before forming the third metal layer 250, a desmear process may be performed to provide roughness to a part of the side surface and the upper surface of the opening 262 of the protective layer 260.

The third metal layer 250 may be formed of an alloy containing silver. The third metal layer 250 may be formed through electroless plating or electrolytic plating.

Finally, the printed circuit board 200 of FIG. 11 may be completed by removing the mask 270.

In addition, the preferred embodiment of the present invention is for the purpose of illustration, those skilled in the art will be possible to various modifications, changes, replacements and additions through the spirit and scope of the appended claims, such modifications and changes are the following patents It should be regarded as belonging to the claims.

Printed Circuit Board 100, 200
Insulation Plate 110, 210
Base pad 122, 222
Circuit pattern 124, 224
First metal layer 130, 230
Second metal layer 140, 240
Third metal layer 150, 250
Protective layer 160, 260

Claims (14)

Insulating layer;
A circuit pattern or pad formed on the insulating layer;
A first metal layer formed on the circuit pattern or pad and including nickel;
A second metal layer formed on the first metal layer and including copper; And
A printed circuit board formed on the second metal layer, the printed circuit board comprising a third metal layer containing silver. The method of claim 1,
The circuit pattern or pad is a printed circuit board formed of an alloy containing copper. The method of claim 1,
The first metal layer is a printed circuit board formed of an alloy further containing phosphorus. The method of claim 1,
The first metal layer has a thickness satisfying 0.1 to 5㎛,
The second metal layer has a thickness satisfying 10 to 100 nm,
The third metal layer is a printed circuit board having a thickness that satisfies 0.1 to 5㎛. The method of claim 1,
At least one of the circuit pattern, the pad, the first metal layer, the second metal layer and the third metal layer has a roughness on the upper surface. The method of claim 1,
And a protective layer formed on the insulating layer and exposing an upper surface of the third metal layer. Preparing an insulating substrate;
Forming a circuit pattern or pad on the insulating substrate;
Forming a first metal layer including nickel on the circuit pattern or pad;
Forming a second metal layer comprising copper on the first metal layer; And
Forming a third metal layer comprising silver on the second metal layer. 8. The method of claim 7,
Forming the first metal layer
Imparting roughness to the surface of the circuit pattern or pad,
And plating the alloy including nickel and phosphorus with the circuit pattern or pad as a seed layer to form the first metal layer. The method of claim 8,
Method of manufacturing a printed circuit board containing 1 to 13% by weight of phosphorus in the first metal layer. 8. The method of claim 7,
Forming the first metal layer
A method of manufacturing a printed circuit board comprising the step of plating an alloy containing nickel and phosphorus on the circuit pattern or pad to meet a thickness of 0.1 to 5㎛. 8. The method of claim 7,
Forming the second metal layer
Imparting roughness to the surface of the first metal layer;
Forming a second metal layer by plating an alloy including copper on the first metal layer. 8. The method of claim 7,
Forming the second metal layer
Plating an alloy comprising copper on the first metal layer to satisfy a thickness of 10 to 100nm. 8. The method of claim 7,
Forming the third metal layer is
Imparting roughness to the surface of the second metal layer;
And electroless plating an alloy including silver on the second metal layer to form a third metal layer. 8. The method of claim 7,
Forming the third metal layer is
Electroless plating an alloy containing silver on the second metal layer so as to satisfy a thickness of 0.1 to 5 μm.

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