JP3191686B2 - Manufacturing method of printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly, to a method for efficiently manufacturing a printed wiring board having a fine wiring circuit pattern with a low defect rate. The present invention relates to a method for manufacturing a printed wiring board which is possible.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a printed wiring board for forming a circuit pattern mainly composed of copper by an etching method of this kind, for example, an imidazole compound insoluble in alkali is used as an etching resist for alkali etching. The method used is described in, for example, JP-A-4-51.
No. 592.

FIG. 5 shows a conventional example of the above-mentioned Japanese Patent Laid-Open No.
It is a longitudinal section of a process order showing a manufacturing method of a printed wired board indicated by −51592 gazettes. That is, as shown in FIG. 5A, electroless copper plating is performed on the insulating substrate 1 and then electrolytic copper plating is performed to form a panel copper plating layer 8 having a thickness of 20 to 30 μm. Next, as shown in FIG. 5B, an alkali-soluble resist ink 9 is screen-printed,
A drying process is performed at 80 ° C. for 10 minutes to form a reverse image having a thickness of about 20 μm.

Next, after treating the insulating substrate 1 with a 5% hydrochloric acid aqueous solution, an acidic aqueous solution of an imidazole compound (imidazole compound: 2%, acetic acid: 3%, ammonia: 0.2%)
%, Copper acetate: 0.5%) at 50 ° C. for 4 minutes, and as shown in FIG. 5C, a 1 μm-thick imidazole compound conversion coating 7 is applied to the copper portion not coated with the resist ink. Form.

[0005] Thereafter, as shown in FIG. 5 (D), the resist ink 3 is peeled off with a 3% aqueous sodium hydroxide solution, and heated and dried at 120 ° C. for 10 minutes. Next, FIG.
As shown in (E), etching was performed using an alkaline etching solution (ammonia-ammonium chloride-copper system, specific gravity: 1.1 to 1.2), and then imidazole was formed with a 3.5% hydrochloric acid aqueous solution. By peeling off the film,
As shown in FIG. 5F, a printed wiring board having a desired copper circuit pattern can be obtained.

[0006]

However, in a method for manufacturing a printed wiring board in which a copper circuit pattern is formed by an etching method using the above-mentioned conventional imidazole compound as an etching resist for alkaline etching, as described above. It is not possible to visually inspect the imidazole compound after the etching resist film is formed, and it is impossible to recognize even if a defect exists in the film. Was virtually impossible.

Therefore, the conventional method has a problem in that the quality of the copper circuit pattern cannot be determined until the etching process is completed, and thus the yield cannot be improved. The reason for this is that the chemical conversion film of the imidazole compound is colorless and transparent, and its thickness is as thin as about 1 μm. The chemical conversion film of the imidazole compound chemically forms a complex with the copper surface by contacting the insulating substrate with an acidic aqueous solution of the imidazole compound, and grows into an accumulated film.

The most common method of contacting the insulating substrate with the acidic aqueous solution of the imidazole compound is by immersion. At this time, the inside of the through hole having a small diameter or a high aspect ratio is treated with a treatment solution. Are likely to stay, and there is a high possibility that an air trap will occur. Further, when the processing temperature is 4
In a medium to high temperature range of 0 to 50 ° C., air bubbles easily adhere to the surface of the insulating substrate.

[0009] The non-contact between the processing solution and the insulating substrate for these reasons hinders the formation of the copper complex and causes the formation of a non-adhered portion of the etching resist and the generation of pinholes. This will cause a defective defect in the copper circuit pattern. On the other hand, in recent years, miniaturization and high performance of electronic devices have been remarkable, and accordingly, high density and miniaturization of copper circuit patterns by printed wiring have been required, and in order to perform such high precision etching processing. It is advantageous that the thickness of the etching resist is thinner. In addition to the method of using a conversion coating of an imidazole compound in the above-described conventional technique, an electrodeposition resist or a liquid resist, a base metal resist, or the like is etched. Attention has been paid to a method of using as a resist.

An object of the present invention is to improve the above-mentioned drawbacks of the prior art, and to provide a method for manufacturing a printed wiring board, in particular, a printed wiring manufactured using a method of forming a fine copper circuit pattern by an etching method. An object of the present invention is to provide a method for manufacturing a printed wiring board which can improve the quality of a board and greatly improve the yield of products.

[0011]

The present invention basically employs the following technical configuration in order to achieve the above object. That is, in a method of manufacturing a printed wiring board in which a predetermined wiring pattern is formed on an insulating substrate, the method includes the steps of: providing an appropriate first resist layer on the insulating substrate; A first step of forming a conductive film layer having a predetermined wiring pattern with a material, and a second step of forming a second resist layer made of a base metal on the conductive film layer having the predetermined wiring pattern
The insulating substrate is treated with a treatment liquid mainly containing an imidazole compound, and the conductive property of the second resist layer is reduced.
A conversion coating of imidazole compound is formed on the film layer
A third step of forming, a fourth step of removing the first resist layer from the insulating substrate, and a fifth step of removing a second resist layer composed of the base metal from the insulating substrate; Are methods for manufacturing a printed wiring board configured to be executed in this order.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In one embodiment of the method for manufacturing a printed wiring board according to the present invention, a step of reversely forming a plating resist on a conductive film on an insulating substrate and a step of treating electrolytic copper plating are performed. And a step of electroplating a base metal resist, and contacting the insulating substrate with an acidic aqueous solution of an imidazole compound so as not to adhere to the conductive film layer of the second resist layer.
Forming a chemical conversion film of an imidazole compound on the part of, a step of peeling off a plating resist, a step of forming a copper circuit pattern by alkali etching, and a step of peeling off a base metal resist, In the final step on the substrate, a wiring portion having a predetermined pattern is to be formed, and a circuit pattern forming portion composed of a conductive film layer mainly composed of copper is covered with a resist layer composed of a base metal, By treating the surface of the resist layer composed of the base metal with a treatment solution mainly composed of an imidazole compound, the imidazole compound is soluble in an acidic solution, shows insolubility in an alkaline solution, and reacts with copper. Utilizing the property of selectively binding to form a complex, there is a possibility that it will be formed on the resist layer composed of the base metal Hole, covering the missing portion of the resist layer composed of a base metal, and used when forming a circuit pattern composed of the conductive film layer mainly composed of copper on the insulating substrate, for example, from a photosensitive material. When the plating resist layer is peeled off, the circuit pattern portion can be completely prevented from being damaged or cut.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific example of a method for manufacturing a printed wiring board according to the present invention will be described in detail with reference to the drawings. That is,
1 and 2 show a method 1 for manufacturing a printed wiring board according to the present invention.
It is a diagram showing a cross-sectional configuration of the insulating substrate for each step in a specific example in the order of steps, by such a diagram, on the insulating substrate is a basic configuration of the method of manufacturing a printed wiring board according to the present invention In a method of manufacturing a printed wiring board on which a predetermined wiring pattern is formed, the method includes the steps of:
By interposing an appropriate first resist layer 3, a conductive film layer 4 having a predetermined wiring pattern of a conductive material is formed.
A second step of forming a second resist layer 5 made of a base metal on the conductive film layer 4 having the predetermined wiring pattern. The first step of forming the insulating substrate 1 mainly with an imidazole compound It was treated with a processing solution to, the second
Imidazo is applied to the part of the resist layer that is not attached to the conductive film layer.
Third step, the fourth step and the second resist layer 5 the insulating substrate configured the base metal or al the resist layer 3 of the first removed from the insulating substrate to form a conversion coating of Le compounds And a fifth step of removing from above the manufacturing method of the printed wiring board.

Particularly, in the present invention, it is preferable that the insulating substrate 1 has a through hole 10 formed therein. That is, as described above, when the through-holes 10 are formed in the insulating substrate 1, air bubbles or air traps are particularly likely to be generated inside the through-holes 10; When the layer 5 is formed, a pinhole is often formed particularly on the inner wall surface of the through hole 10 or the second resist layer is not formed, and in a later step, the first resist layer is formed. In the processing step of removing the third resist layer 3, the stripping agent of the first resist layer 3 penetrates from the pinhole or the portion where the second resist layer 5 is not formed, thereby destroying, cutting, and removing the circuit pattern. Therefore, in the present invention,
It is particularly effective to apply to such an insulating substrate.

The insulating substrate 1 used in the present invention comprises:
Although it is not particularly limited, any general insulating substrate can be used. In applying the method for manufacturing a printed wiring board of the present invention, it is preferable that the conductive film layer forming the circuit pattern of the printed wiring board employs an electroplating method. The insulating substrate 1
It is preferable that a part or the whole of the surface is covered with a predetermined conductive film 2 in advance as shown in FIG.

The conductive film is not particularly limited as long as it is a material having conductivity. However, preferably, the conductive film mainly composed of copper formed by electroless copper plating is used. It is. In the first embodiment according to the present invention shown in FIG. 1 and FIG. 2, first, as shown in FIG. After a first resist layer 3 made of a material is arranged and formed on a portion on the insulating substrate 1 except for a portion where a predetermined wiring pattern 11 is to be formed, as shown in FIG. A conductive film layer 4 made of a conductive material constituting an actual circuit pattern is formed on the conductive film 2 on the insulating substrate on which the first resist layer 3 is not formed. .

The method of forming the conductive film layer 4 in the present invention is not particularly limited. For example, it is preferable that the conductive film layer 4 is formed of a conductive material mainly composed of copper. And pattern copper plating using an electric copper plating method. In the method of manufacturing in printed wiring board in the present invention, then, Figure 1 as shown in (D), second configured base metal or al on the conductive film layer 4 having the predetermined wiring pattern Of forming the resist layer 5 of FIG.

In the present invention, the second resist layer 5 comprises:
When performing a step of peeling and removing the first resist layer 3 to be described later, which serve to protect the conductive layer 4, also constitute a resist layer 5 of the second noble
The metal is not particularly limited. For example, a metal material such as solder or tin is used. In the present invention, such a metal material forms the resist layer 5 using, for example, an electroplating method.

In FIG. 1D, for example, the second resist layer 5 made of a base metal formed on the inner surface of the pinhole 10 of the insulating substrate 1 by the presence of bubbles or the like.
2 shows a state in which the unplated portion 6 is formed.
After that, as shown in FIG. 2A, the insulating substrate 1 on which the second resist layer 5 is formed is immersed in a treatment liquid mainly containing an imidazole compound to treat the surface of the insulating substrate 1. Unplated portion 6 of second resist layer 5 formed on the inner surface of pinhole 10 of insulating substrate 1
Alternatively, the treatment liquid component mainly composed of the imidazole compound selectively binds to the conductive film layer 4 through a pinhole to form a complex, and the conversion coating 7 of the imidazole compound is not deposited on the plating. The opening of the portion 6 or the pinhole portion is completely covered, and the defective portion called the unplated portion 6 or the pinhole portion is repaired.

Next, as shown in FIG. 2B, a step of peeling and removing the first resist layer 3 from the insulating substrate 1 and a second resist layer 5 as shown in FIG. Using the mask as a mask, the conductive film 2 formed on the surface of the insulating substrate 1 is peeled and removed by a method such as an etching process to form a printed wiring board as a final product as shown in FIG. You.

The first specific example of the method for manufacturing a printed wiring board according to the present invention will be described in more detail.
In FIG. 1A, an insulating substrate 1 having a through hole 10 is subjected to electroless copper plating to form a conductive film 2 having a thickness of about 2 μm. Then, as shown in FIG. A photosensitive layer having a thickness of about 50 μm, for example, a film made of a dry film or the like is laminated on the conductive film 2 as a plating resist in a plating process to be described later, and is exposed and developed using a mask having a predetermined pattern. The processing is performed to form the first resist layer 3 in a portion other than the region where the predetermined copper circuit pattern is formed.

Subsequently, as shown in FIG. 1C, the insulating substrate 1 is placed in an electrolytic copper plating bath (for example, the composition ratio is copper sulfate: 8).
5 g / l, sulfuric acid: 190 g / l, chloride ion: 50 mg
/ L of a copper plating bath) and a current density of 2.5 A
/ Dm ² for about 50 minutes to form a conductive film layer 4 on the conductive film 2 not covered with the photosensitive layer 3.
Of about 30 μm is formed.

Thereafter, as shown in FIG. 1D, the insulating substrate 1 is placed in an electric solder plating bath (for example, when the composition ratio is tin (l).
l): 15 g / l, lead: 10 g / l, borofluoric acid: 400 g / l, boric acid: 25 g / l, peptone: 5
g / l) at a current density of 1.2 A / dm ² for about 15 minutes to form a solder on the patterned copper plating layer 4 as the second resist layer 5 made of a base metal of about 8 μm. The plating layer 5 is formed as an etching resist.

Since the solder plating layer 5 is a very thin film, if the plating bath is not properly controlled or if the stirring during the plating process is not appropriate, the plating voids such as plating voids and pinholes may not be formed. The attached portion 6 is formed, and as described above, the metal constituting the circuit pattern, that is, copper, which is exposed through the unplated portion 6 is erroneously etched, which causes a defect of the circuit pattern. .

However, in the present invention, FIG.
As shown in the figure, the insulating substrate 1 is treated with an acidic aqueous solution treatment bath mainly composed of an imidazole compound (composition ratio is, for example, imidazole compound: 1%, copper ion: 200 ppm, formic acid: 4
%) At 40 ° C. for 1 minute to selectively form the imidazole compound conversion coating 7 on the unsoldered portions 6 (copper exposed portions).
, It is possible to easily avoid the loss of the copper circuit pattern.

In the present invention, when performing such immersion treatment, ultrasonic treatment is used in combination with immersion treatment of the insulating substrate 1 in an acidic aqueous solution treatment bath mainly containing the imidazole compound. As a result, the treatment liquid is circulated and the bubbles are defoamed positively, so that it is effective in promoting the film formation even in the inside of the through hole having a high aspect ratio.

Next, as shown in FIG. 2B, the photosensitive layer 3, which is the first resist layer, is dissolved and peeled with 2 to 3% sodium hydroxide, and then, as shown in FIG. , An alkaline etching solution (composition ratio is, for example, copper: 140 g /
l, chlorine: 150 g / l, ammonia: 8.5 g / l)
The conductive film 2 is etched by using the method described above to form a copper circuit pattern, and the second resist layer, the solder plating 5 and the imidazole compound conversion film 7 are stripped off with a nitric acid-based stripping agent. Thereby, the printed wiring board is completed.

Next, a second embodiment of the method for manufacturing a printed wiring board according to the present invention will be described with reference to FIGS. That is, FIGS. 3 and 4 are views showing the cross-sectional configuration of the insulating substrate in each step in another specific example of the method for manufacturing a printed wiring board according to the present invention in the order of steps. 1
The difference between this embodiment and this embodiment is that, in the first embodiment, the first resist layer 3 is formed on the surface of the insulating substrate 1 having the conductive film 2 and then the pattern copper plating or the like is performed. By forming the conductive film layer 4 mainly composed of copper constituting a circuit pattern in the portion between the first resist layers 3 by performing After a conductive film layer 4 is formed by directly performing a process such as pattern copper plating on the entire surface of the insulating substrate 1 having the coating 2, a first resist layer is formed on the surface of the conductive film layer 4. 3 and the other steps are substantially the same.

That is, in FIG. 3A, the insulating substrate 1 having the through holes 10 is subjected to electroless copper plating to form a conductive film 2 having a thickness of about 2 μm. As shown in the figure, a circuit wiring portion having a predetermined pattern described later is formed on the conductive film 2 entirely over the conductive film layer 4 partially formed by the circuit wiring portion. An insulating copper plating bath (for example, a composition ratio of copper sulfate: 85 g / l, sulfuric acid: 190 g / l, chlorine ion: 5)
0 mg / l copper plating bath) and a current density of 2.5 A / dm ² for about 50 minutes,
A panel copper plating layer 4 having a thickness of about 30 μm, which is a conductive film layer 4, is formed on the conductive film 2 of the insulating substrate 1.

Next, as shown in FIG. 3C, a photosensitive layer having a thickness of about 50 μm as a plating resist, for example, a film made of a dry film or the like is laminated on the conductive film layer 4 to form a predetermined pattern. A known exposure and development process is performed using a mask having the following formula, and the first resist layer 3 is formed in a portion other than a region where a predetermined copper circuit pattern is formed.

Thereafter, as shown in FIG. 3D, the insulating substrate 1 is placed in an electric solder plating bath (for example, when the composition ratio is tin (l
l): 15 g / l, lead: 10 g / l, borofluoric acid: 400 g / l, boric acid: 25 g / l, peptone: 5
g / l) at a current density of 1.2 A / dm ² for about 15 minutes, so that about 8
second resist layer 5 is a solder plating layer 5 that is a base metal or al structure of μm is formed as an etching resist.

Next, in the present invention, as shown in FIG. 4A, the insulating substrate 1 is treated with an acidic aqueous solution treatment bath mainly composed of an imidazole compound (composition ratio is, for example, imidazole compound: 1%, copper ion : 200 ppm, formic acid: 4%)
At 40 ° C. for 1 minute to selectively form the chemical conversion film 7 of the imidazole compound on the undeposited portion of the etching resist, that is, on the unsoldered portion 6 (copper exposed portion).

Next, as shown in FIG. 4B, the photosensitive layer 3, which is the first resist layer, is dissolved and peeled with 2 to 3% sodium hydroxide, and then, as shown in FIG. , An alkaline etching solution (composition ratio is, for example, copper: 140 g /
l, chlorine: 150 g / l, ammonia: 8.5 g / l)
The conductive film 2 is etched by using the method described above to form a copper circuit pattern, and the second resist layer, the solder plating 5 and the imidazole compound conversion film 7 are stripped off with a nitric acid-based stripping agent. Thereby, the printed wiring board is completed.

[0034]

In the method for manufacturing a printed wiring board according to the present invention, high density and high density can be obtained by using an etching method.
Quality of printed wiring boards with miniaturized circuit patterns,
It has become possible to provide a method for manufacturing a printed wiring board that can improve the performance and greatly improve the product yield.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an outline of a cross-sectional structure of an insulating substrate in each step in a specific example of a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 2 is a cross-sectional view showing an outline of a cross-sectional structure of an insulating substrate in each step in a specific example of a method of manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 3 is a sectional view schematically showing a sectional structure of an insulating substrate in each step in the order of steps in another specific example of the method for manufacturing a printed wiring board according to the present invention.

FIG. 4 is a cross-sectional view schematically illustrating the cross-sectional structure of the insulating substrate in each step in another specific example of the method for manufacturing a printed wiring board according to the present invention in the order of steps.

FIG. 5 is a sectional view schematically showing the sectional structure of an insulating substrate in each step in a conventional method of manufacturing a printed wiring board in the order of steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... Conductive film 3, 9 ... First resist layer 4, 8 ... Conductive film layer 5 ... Second resist layer, plating layer composed of base metal 6 ... Unplated portion, pinhole Part 7: Chemical conversion film part of imidazole compound 10 ... Through hole 11 ... Circuit pattern constituent part

Claims (10)

(57) [Claims] 1. A method of manufacturing a printed wiring board having a predetermined wiring pattern formed on an insulating substrate, the method comprising the steps of: interposing an appropriate first resist layer on the insulating substrate; A first step of forming a conductive film layer having a predetermined wiring pattern using a conductive material, and a second step of forming a second resist layer made of a base metal on the conductive film layer having the predetermined wiring pattern. Step 2, the insulating substrate is treated with a treatment liquid mainly containing an imidazole compound,
In the portion of the second resist layer not attached to the conductive film layer
A third step of forming a chemical conversion film of the imidazole compound ,
A fourth step of removing the first resist layer from the insulating substrate;
And a fifth step of removing the second resist layer composed of the base metal from the insulating substrate, in this order. Production method. 2. The method for manufacturing a printed wiring board according to claim 1, wherein said insulating substrate has a part or the whole surface thereof previously coated with a predetermined conductive film. 3. The method for manufacturing a printed wiring board according to claim 1, wherein the insulating substrate has a through-hole formed therein. 4. The first step is to form an appropriate first resist layer on a portion of the insulating substrate excluding a portion where a predetermined wiring pattern is to be formed on the insulating substrate. And a step of forming a conductive film layer made of a conductive material on a portion of the insulating substrate where the first resist layer is not formed. 4. The method for manufacturing a printed wiring board according to any one of 1 to 3. 5. The method according to claim 1, wherein the first step includes forming a conductive film layer made of a conductive material on a part or all of the insulating substrate in advance, and forming a predetermined wiring pattern. 4. A step of arranging and forming an appropriate first resist layer on the portion of the conductive film layer on the insulating substrate excluding the portion. Manufacturing method of printed wiring board. 6. The method for manufacturing a printed wiring board according to claim 2, wherein the conductive coating previously covering a part or all of the surface of the insulating substrate is a thin film mainly composed of copper. . 7. The method according to claim 1, wherein the step of forming the conductive film layer made of the conductive material in the first step uses an electrolytic copper plating process.
6. The method for manufacturing a printed wiring board according to any one of 4 and 5. 8. The step of removing the first resist layer from the insulating substrate, and the step of removing the second resist layer from the insulating substrate.
Using the resist layer as a mask to remove the conductive coating located on the insulating substrate where the first resist layer has been removed. 3. The method for producing a printed wiring board according to item 2. 9. The step of removing the first resist layer from the insulating substrate, and the step of removing the second resist layer from the insulating substrate.
Removing the conductive film layer and the conductive film located on the insulating substrate where the first resist layer has been removed, using the resist layer as a mask. The method for manufacturing a printed wiring board according to claim 5, wherein 10. The fifth step is to simultaneously remove a second resist layer composed of a base metal and an imidazole compound contained in the second resist layer. A method for manufacturing a printed wiring board according to claim 1.