JP2004095983A - Manufacturing method of printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a printed wiring board which removes an unnecessary part of a foundation layer and at the same time protects a necessary foundation layer during soft etching in the formation of a metal wiring pattern in manufacturing a printed wiring board by a semi-additive method. <P>SOLUTION: A foundation layer 1 is formed by thinning first metal foil by a chemical polishing solution, a mask pattern 3 is formed, a plating film 4 of a second metal is formed by electrolytic plating in an exposed foundation layer, a plating film 5 of a first metal is formed on the plating film, a mask pattern is peeled, a foundation 1' which is unnecessary is removed, and a metal wiring pattern 6 constituted of the foundation layer of the first metal, the plating film of the second metal and the plating film of the fist metal is formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a printed wiring board by a semi-additive method.
[0002]
[Prior art]
A subtractive method is widely used for forming a conductor pattern when manufacturing a printed wiring board. However, in recent years, the subtractive method has responded to the demand for higher density of the wiring board itself, that is, miniaturization of the conductor pattern with the miniaturization, higher density mounting, and higher performance (higher speed) of electronic devices. It is the present situation that is no longer possible. A semi-additive method is used as an effective means for forming a finer pattern.
[0003]
Until now, in order to manufacture a printed wiring board by the semi-additive method, first, a thin copper base layer is formed on the entire surface of an insulating substrate, and then a photoresist for plating is formed on the surface of the copper base layer. A mask pattern is formed.
Next, a copper plating film is formed by an electrolytic plating method, and the mask pattern of the photoresist is removed. Finally, a printed wiring board is manufactured by a method of forming a copper wiring pattern by removing unnecessary portions of a copper base layer by soft etching.
[0004]
[Problems to be solved by the invention]
The semi-additive method can form a finer copper wiring pattern than the subtractive method, but has a problem. It is mainly in a soft etching process for removing an unnecessary portion of the copper base layer. That is, it was found that the width of the copper underlayer tended to be narrower during the soft etching, and that the copper wiring pattern was peeled off from the substrate.
The present invention is not limited to a copper underlayer, and does not require an underlayer even in the case of another metal underlayer during the soft etching when forming a metal wiring pattern in the production of a printed wiring board by a semi-additive method. It is an object of the present invention to provide a method of manufacturing a printed wiring board which can protect a necessary underlayer while removing a portion.
[0005]
[Means for Solving the Problems]
The present invention relates to a method for manufacturing a printed wiring board, wherein a metal wiring pattern is formed by a semi-additive method on an insulating substrate with a first metal foil.
1) a step of thinning a first metal foil on an insulating substrate with a chemical polishing solution to form a first metal base layer for electrolytic plating conduction;
2) forming a mask pattern for forming a metal wiring pattern by electrolytic plating on the insulating substrate on which the base layer has been formed;
3) forming a plating film of a second metal on the exposed underlying layer other than the mask pattern by electrolytic plating;
4) forming a plating film of the first metal on the plating film of the second metal by electrolytic plating;
5) a step of stripping the mask pattern with a stripping solution;
6) a step of removing unnecessary base layer portions by soft etching;
And forming a metal wiring pattern including a first metal base layer, a second metal plating film, and a first metal plating film.
[0006]
Further, the present invention relates to a method of manufacturing a printed wiring board for forming a metal wiring pattern on a first metal foil-attached insulating substrate by a semi-additive method,
1) a step of thinning a first metal foil on an insulating substrate with a chemical polishing solution to form a first metal base layer for electrolytic plating conduction;
2) forming a mask pattern for forming a metal wiring pattern by electrolytic plating on the insulating substrate on which the base layer has been formed;
3) forming a plating film of a second metal on the exposed underlying layer other than the mask pattern by electrolytic plating;
4) a step of forming a plating film of a third metal on the plating film of the second metal by electrolytic plating;
5) a step of stripping the mask pattern with a stripping solution;
6) a step of removing unnecessary base layer portions by soft etching;
And forming a metal wiring pattern composed of a first metal base layer, a second metal plating film, and a third metal plating film.
[0007]
Further, the present invention is the method of manufacturing a printed wiring board according to the above invention, wherein the insulating substrate is selected from a polyimide and a liquid crystal polymer.
[0008]
The present invention also provides the method for manufacturing a printed wiring board according to the above invention, wherein each of the first metal, the second metal, and the third metal is Ni, Cr, Au, Cu, Ag, Al, Sn, A method for manufacturing a printed wiring board, wherein the method is selected from Zn and Pb.
[0009]
Further, the present invention is the method for manufacturing a printed wiring board according to the above invention, wherein the thickness of the plating film of the second metal is 0.1 μm to 5 μm.
[0010]
Further, the present invention is the method for manufacturing a printed wiring board according to the present invention, wherein the thickness of the underlayer is 0.1 μm to 3 μm.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described based on its embodiments.
FIG. 1 is a process drawing showing a cross section of one embodiment of the method for manufacturing a printed wiring board according to the present invention. As shown in FIG. 1A, in the method of manufacturing a printed wiring board according to the present invention, first, a first metal foil adhered on an insulating substrate 2 is thinned by chemical polishing, and a base layer 1 for conducting electroplating is formed. To form The thickness of the underlayer 1 is 0.1 μm to 3 μm, and preferably 1 μm or less.
As the insulating substrate 2, polyimide, liquid crystal polymer, or the like can be used.
[0012]
The first metal can be selected from Ni, Cr, Au, Cu, Ag, Al, Sn, Zn, Pb, and the like. The chemical used for chemical polishing varies depending on the first metal. For example, in the case of copper, aqueous hydrogen peroxide + sulfuric acid or ammonium persulfate can be used. In the case of nickel, for example, Mech Remover NH-1862 (trade name) manufactured by Mec can be used.
[0013]
Next, as shown in FIG. 1 (2), a dry film is laminated on the insulating substrate 2 on which the base layer is formed, and through a process such as exposure and development, a mask pattern for plating for forming a metal wiring pattern is formed. Form 3 The thickness of the dry film is 10 μm to 30 μm, preferably 15 μm.
Next, as shown in FIG. 1C, a plating film 4 of a second metal is formed on the exposed portion of the base layer 1 by an electrolytic plating method. The thickness of the second metal plating film 4 is 0.1 μm to 5 μm, and preferably 3 μm or less.
The second metal can be selected from Ni, Cr, Au, Cu, Ag, Al, Sn, Zn, Pb, and the like.
[0014]
Next, as shown in FIGS. 1 (4) to (6), a first metal or third metal plating film 5 is further formed on the second metal plating film 4, and a dry film The mask pattern 3 is removed, and the unnecessary underlayer portion 1 'of the underlayer is removed by soft etching to form a desired metal wiring pattern 6 (1 + 4 + 5). The third metal can be selected from Ni, Cr, Au, Cu, Ag, Al, Sn, Zn, Pb, and the like.
[0015]
As described above, conventionally, when forming a copper wiring pattern by the semi-additive method, if soft etching is performed to remove an unnecessary copper underlayer, the width of the copper underlayer is larger than that of the copper plating film. When a copper wiring pattern becomes thinner, particularly when a fine copper wiring pattern is formed, it is observed that the copper wiring pattern is frequently peeled off because the line width is small. This is due to the footing of the mask pattern of the dry film.
In other words, the copper plating film on the copper underlayer should naturally be a protective layer of the copper underlayer, but because of the footing, the contact width of the copper plating film in contact with the copper underlayer Is smaller than the width of the copper plating film, and the width of the protected copper underlayer is also smaller than the width of the copper plating film. Also, when soft etching is performed, the width of the copper wiring pattern is reduced due to side etching. The width of the copper underlayer becomes further narrower as the whole becomes thinner, so that the copper wiring pattern is liable to peel off.
[0016]
The present invention is a method for forming a metal wiring pattern made to solve this problem.
That is, first, a thin second metal plating film 4 is formed on the underlayer 1 using a metal different from the first metal underlayer 1, and the thin plating film 4 is electrolytically plated on the thin plating film 4 by, for example, A third metal plating film 5 which is the same as the first metal underlayer 1 or different from the first metal underlayer 1 and the thin second metal plating film 4 is formed.
At this time, if a soft etching solution that does not affect the thin plating film 4 on the base layer 1 is selected, the thin plating film 4 serves as a protective layer, and side etching occurs in the protective layer when performing soft etching. Therefore, the width of the protective layer does not become thin, and the necessary underlayer can be protected with a stable width.
[0017]
For example, a metal wiring pattern is formed using copper as the first metal as the first metal, nickel as the second metal as the thin plating film 4 on the underlying layer, and copper as the first metal as the third metal 5 as the plating film 5 on the underlayer. In this case, if the soft etching solution is hydrogen peroxide solution + sulfuric acid or ammonium persulfate, the nickel plating film 4 is hardly damaged during the soft etching, so that the copper base layer can be protected.
Further, for example, a metal wiring pattern using nickel as the first metal as the underlayer 1, copper as the second metal as the thin plating film 4 on the underlayer, and nickel as the first metal as the third metal as the plating film 5 When the soft etching solution is changed to Mech Remover NH-1862 manufactured by Mec Co., the copper plating film 4 is hardly damaged at the time of soft etching, so that the nickel underlayer can be protected. .
[0018]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
<Example 1>
In the first embodiment, the first metal and the third metal are copper, and the second metal is nickel.
First, a copper foil of a first metal adhered to a surface of a polyimide as an insulating substrate is chemically polished with a soft etching solution of ammonium persulfate to a thickness of 1 μm, and the copper for the electroplating conduction (the first metal) is removed. ) Was formed (see FIG. 1A).
[0019]
Next, an NIT (trade name) dry film (film thickness: 15 μm) manufactured by Nichigo Morton Co., Ltd. was laminated on the surface of the polyimide substrate on which the copper base layer was formed at 100 ° C. and a pressure of 3 kgf / cm ² , and about 50 mJ / The mask pattern 3 for electrolytic plating was formed by selectively exposing to ultraviolet light of cm ² and developing with a 1% sodium carbonate solution at 30 ° C. for about 10 seconds (see FIG. 1 (2)).
Next, a 2 μm-thick nickel (second metal) plating film 4 was formed on the exposed portion of the copper underlayer by electrolytic plating on the polyimide substrate on which the copper underlayer and the mask pattern were formed. (See FIG. 1 (3)).
[0020]
Next, a copper (third metal) plating film 5 having a thickness of 10 μm is further formed on the nickel plating film 4 (see FIG. 1 (4)). % Sodium carbonate solution (see FIG. 1 (5)).
Soft etching is performed with the same chemical solution as used in the chemical polishing to remove the unnecessary copper underlayer 1 ′, and remove the copper (first metal) underlayer 1, nickel (second metal) plating film 4, copper A metal wiring pattern composed of the (third metal) plating film 5 was formed (see FIG. 1 (6)).
[0021]
<Example 2>
In the second embodiment, the first metal and the third metal are nickel, and the second metal is copper.
First, the first metal nickel foil adhered to the surface of a polyimide as an insulating substrate was chemically polished to a thickness of 1 μm by using Mech Remover NH-1862 manufactured by Mec Co., Ltd. as a soft etching solution. An underlayer 1 of general nickel (first metal) was formed (see FIG. 1A).
[0022]
Next, an NIT (trade name) dry film (film thickness: 15 μm) manufactured by Nichigo Morton Co., Ltd. was laminated at 100 ° C. under a pressure of 3 kgf / cm ² on the surface of the polyimide substrate on which the nickel base layer was formed, and the pressure was about 50 mJ / cm ^2. The mask pattern 3 for electrolytic plating was formed by selectively exposing to ultraviolet light of cm ² and developing with a 1% sodium carbonate solution at 30 ° C. for about 10 seconds (see FIG. 1 (2)).
Next, a 2 μm-thick copper (second metal) plating film 4 was formed on the exposed portion of the nickel underlayer by electrolytic plating on the polyimide substrate on which the nickel underlayer and the mask pattern were formed. (See FIG. 1 (3)).
[0023]
Next, a nickel (third metal) plating film 5 having a thickness of 10 μm is further formed on the copper plating film 4 (see FIG. 1 (4)). % Sodium carbonate solution (see FIG. 1 (5)).
Soft etching is performed with the same chemical solution as that used in the chemical polishing to remove the unnecessary nickel base layer, and then a nickel (first metal) base layer 1, a copper (second metal) plating film 4, and a nickel (second metal) A metal wiring pattern composed of a plating film 5 of (3 metals) was formed (see FIG. 1 (6)).
[0024]
<Example 3>
In the third embodiment, the first metal is copper, the second metal is nickel, and the third metal is gold.
First, the first metal copper foil adhered to the surface of polyimide as an insulating substrate is chemically polished to a thickness of 1 μm by using Mech Remover NH-1862 manufactured by Mec Co., Ltd. as a soft etching solution. A common copper (first metal) underlayer 1 was formed (see FIG. 1A).
[0025]
Next, an NIT (trade name) dry film (film thickness: 15 μm) manufactured by Nichigo Morton Co., Ltd. was laminated on the surface of the polyimide substrate on which the copper base layer was formed at 100 ° C. and a pressure of 3 kgf / cm ² , and about 50 mJ / The mask pattern 3 for electrolytic plating was formed by selectively exposing to ultraviolet light of cm ² and developing with a 1% sodium carbonate solution at 30 ° C. for about 10 seconds (see FIG. 1 (2)).
Next, a 2 μm-thick nickel (second metal) plating film 4 was formed on the exposed portion of the copper underlayer by electrolytic plating on the polyimide substrate on which the copper underlayer and the mask pattern were formed. (See FIG. 1 (3)).
[0026]
Next, a gold (third metal) plating film 5 having a thickness of 10 μm is further formed on the nickel plating film 4 (see FIG. 1 (4)). % Sodium carbonate solution (see FIG. 1 (5)).
Soft etching is performed with the same chemical solution as used in the chemical polishing, and the unnecessary copper underlayer is removed. Copper (first metal) underlayer 1, nickel (second metal) plating film 4, gold (second metal) A metal wiring pattern composed of a plating film 5 of (3 metals) was formed (see FIG. 1 (6)).
[0027]
【The invention's effect】
The present invention provides a step of forming a base layer of a first metal, a step of forming a mask pattern, a step of forming a plating film of a second metal, a step of forming a plating film of a first metal, a step of forming a mask pattern And a metal wiring pattern comprising a first metal underlayer, a second metal plating film, and a first metal or third metal plating film. Since the method is a method for manufacturing a printed wiring board for forming a metal wiring pattern, an unnecessary portion of the base layer is not limited to the copper base layer even if it is another metal base layer during soft etching when forming a metal wiring pattern. A method for manufacturing a printed wiring board that can protect a necessary underlayer at the same time as the removal is provided.
[Brief description of the drawings]
FIG. 1 is a process drawing showing a cross section of one embodiment of a method for manufacturing a printed wiring board according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... 1st metal base layer 1 '... Unnecessary base layer part 2 ... insulating substrate 3 ... mask pattern 4 ... 2nd metal plating film 5 ... 1st Or the third metal plating film 6: metal wiring pattern

Claims (6)

In a method for manufacturing a printed wiring board, wherein a metal wiring pattern is formed on a first metal foil-attached insulating substrate by a semi-additive method,
1) a step of thinning a first metal foil on an insulating substrate with a chemical polishing solution to form a first metal base layer for electrolytic plating conduction;
2) forming a mask pattern for forming a metal wiring pattern by electrolytic plating on the insulating substrate on which the base layer has been formed;
3) forming a plating film of a second metal on the exposed underlying layer other than the mask pattern by electrolytic plating;
4) forming a plating film of the first metal on the plating film of the second metal by electrolytic plating;
5) a step of stripping the mask pattern with a stripping solution;
6) a step of removing unnecessary underlayer portions by soft etching;
And forming a metal wiring pattern including a first metal base layer, a second metal plating film, and a first metal plating film. In a method for manufacturing a printed wiring board, wherein a metal wiring pattern is formed on a first metal foil-attached insulating substrate by a semi-additive method,
1) a step of thinning a first metal foil on an insulating substrate with a chemical polishing solution to form a first metal base layer for electrolytic plating conduction;
2) forming a mask pattern for forming a metal wiring pattern by electrolytic plating on the insulating substrate on which the base layer has been formed;
3) forming a plating film of a second metal on the exposed underlying layer other than the mask pattern by electrolytic plating;
4) a step of forming a plating film of a third metal on the plating film of the second metal by electrolytic plating;
5) a step of stripping the mask pattern with a stripping solution;
6) a step of removing unnecessary underlayer portions by soft etching;
A method of manufacturing a printed wiring board, comprising: forming a metal wiring pattern including a base layer of a first metal, a plating film of a second metal, and a plating film of a third metal. 3. The method for manufacturing a printed wiring board according to claim 1, wherein the insulating substrate is selected from a polyimide and a liquid crystal polymer. The metal of each of the first metal, the second metal, and the third metal is selected from Ni, Cr, Au, Cu, Ag, Al, Sn, Zn, and Pb. The method for producing a printed wiring board according to claim 1, 2, or 3. The method for manufacturing a printed wiring board according to claim 1, wherein the thickness of the plating film of the second metal is 0.1 m to 5 m. 6. The method for manufacturing a printed wiring board according to claim 1, wherein the underlayer has a thickness of 0.1 μm to 3 μm.

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