JP2000294900A - Method for working wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work method of a wiring board which is superior in work stability, which can collectively work a large area and which is superior in operability, flexibility and cost. SOLUTION: At the time of using developer containing alkali metal such as sodium and potassium, which is generally used as the developer of acrylic group dry film resist, alkali metal ions adsorbed on a dry film are cleaned by inorganic acid such as hydrochloric acid and sulfuric acid, and organic acid such as oxalic acid and citric acid. Thus, it is removed from the surface layer of a resist film. Then, possibility that fluorine by means of fluorine gas used at the dry etching and alkali metal react and salt fluoride with high plasma resistance is generated on the dry film is eliminated. Consequently, the defect of etching remainder is reduced and yield can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor package member, a semiconductor mounting member, and a method of processing an insulating layer of a wiring board of a magnetic head suspension in a magnetic disk drive.

[0002]

2. Description of the Related Art Conventionally, the following three types of processing methods have been known as processing methods for insulating resin used in electronic members. As a first processing method, there is a processing method using chemical etching. For example, in the case of an imide-based heat-resistant resin such as polyimide, a method of performing chemical etching using a concentrated alkaline aqueous solution or an organic alkaline solution such as hydrazine is used.
As a second processing method, there is a method of processing with a laser. For example, in the case of an imide-based resin or an epoxy-based resin, a method of processing using a carbon dioxide gas, an excimer, a YAG laser, or the like is used. As a third processing method, there is a processing method using plasma etching. For example, in the field of semiconductor manufacturing, L
Processing of polyimide for the passivation film of SI can be exemplified. It is also used for applications such as TAB and printed circuit board manufacturing.

The first processing method of processing imide resin by chemical etching has been well known for a long time and has been widely used. However, some types of resins are difficult to etch due to differences in the basic skeleton. Further, there is a first problem that an organic alkali compound such as hydrazine constituting the etching solution is harmful to the human body and difficult to handle.

[0004] The resin processing method using a laser, which is the second processing method, is not suitable for batch processing of a large area because a single processing area is within a range of a laser diameter.
There is a problem.

In a resin processing method using plasma etching, which is a third processing method, a photosensitive resist such as a novolak liquid resist is generally used as a mask for forming a pattern. However, there is a third problem that a novolak liquid resist or the like as a photosensitive resist is difficult to handle and expensive.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a method of processing a wiring board which solves these problems. First, as a processing method, a processing method by plasma etching is adopted in order to solve the first and second problems. This eliminates the use of chemicals harmful to the human body, such as hydrazine, so that work safety is excellent, large-area batch processing is possible, and etching can be performed regardless of the type of basic skeleton of the insulating resin. In order to solve the third problem, an acrylic dry film resist is employed. This results in excellent handling, flexibility and cost.

When an acrylic dry film resist is used as a resist for plasma etching, it has been found that when a fluorine-based reaction gas is used during plasma etching, crystals having high plasma resistance are generated on the surface of the dry film. If this falls down on the etched surface of the insulating resin, a new problem occurs that the insulating resin immediately below remains without being etched.

As a result of various analyses, crystals having high plasma resistance are presumed to be fluoride salts. This phenomenon can be inferred as follows. First, sodium or potassium in sodium carbonate or potassium carbonate used as a developer is bonded to a carboxyl group or a hydroxyl group exposed on the surface layer of the dry film resist. This combined substance remains on the surface layer of the dry film resist and is further combined with fluorine contained in the reaction gas for dry etching to form a fluoride salt 16. It is presumed that the fluoride salt is a crystal having high plasma resistance, falls down on the etched surface of the insulating resin, and remains, and the etching residue 17 of the insulating resin is generated.

[0009] As shown in FIG.
The insulating resin layer 11 is etched by the plasma 19 from the opening 20 of the substrate (plasma etching process). At this time, the fluoride salt 16 is already generated on the surface layer of the dry film resist 13. As shown in FIG. 5 (i), the fluoride salt 16 is a crystal having high plasma resistance and falls down on the etched surface of the insulating resin 11 and remains, and the etching residue 17 of the insulating resin is generated. It is speculated that.

The present invention is intended to solve such a new problem, and it is intended to eliminate by-products on a resist during plasma etching and to reduce defects in plasma etching remaining on an insulating resin, and to process a wiring board. It is also intended to provide a method.

[0011]

In a wiring board having a circuit pattern of a metal conductor layer formed on an insulator layer, a first step of forming a dry film resist layer having a desired pattern on the wiring board. And a second step of removing the insulator layer from the opening of the resist layer by plasma etching, and a third step of peeling and removing the resist layer. .

In the first step, it is more preferable to use a developing solution containing an alkali metal as a developing solution for the resist layer, and to have a washing step with an acid after the developing treatment. More preferably, the resist layer is an acrylic alkali-developing dry film resist. Further, it is more desirable that the reaction gas used in the plasma etching treatment in the second step is a fluorine compound.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an outline of a processing procedure according to an embodiment of the present invention. A procedure for processing the insulating resin of a wiring board having a copper wiring pattern formed on one side of the insulating resin and a copper solid wiring pattern formed on the other side will be described below. First, an acrylic dry film resist is laminated on the wiring substrate as a mask pattern for plasma etching on a substrate on which a copper wiring pattern is formed. Second, the dry film resist is exposed with a photomask having a desired pattern shape so as to have a desired pattern shape. Third, development is performed with a developer containing an alkali metal. Here, a substance containing an inorganic alkali component such as sodium carbonate or potassium carbonate is used as a developer. Fourth, pickling is performed to remove the alkali metal adsorbed on the dry film resist. Here, the alkali metal adsorbed on the surface layer of the dry film resist film is washed using an inorganic acid such as hydrochloric acid or sulfuric acid, or an organic acid such as bromic acid or citric acid.
Fifth, the insulating resin layer is etched away from the opening of the resist by a plasma etching method in a fluorine-based gas atmosphere. Sixth, the dry film resist is stripped using a stripper. Here, an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be used as the stripping solution.

As an example of the above embodiment of the present invention,
This will be described with reference to FIGS. First, as the insulating resin processed in the present invention, an epoxy resin, an imide heat-resistant resin, a polyester resin, a urethane resin, a polystyrene resin, a polyethylene resin, a polyamide resin, an ABS resin, a polycarbonate resin, a silicone resin A thermoplastic resin or a thermosetting resin such as a system resin can be used. For example, generally used as an electronic component material, a film such as Kapton manufactured by Dupont Toray Co., a laminated material of metal and polyimide such as Upisel manufactured by Ube Industries, or a carrier such as a thin metal. After applying a varnish of polyamic acid in the form of a film, and then curing it with heat and imidizing it, it can be used. Further, the thickness of the insulating resin layer can correspond to 0.1 to 100 μmt, and is particularly suitable for processing the insulating resin layer having a thickness of 1 to 50 μmt.

In FIG. 2A, a copper wiring pattern 12 is formed on a polyimide film 11 which is an insulating resin layer. Here, one side is a copper solid wiring pattern 12.

In FIG. 2B, an acrylic alkali-soluble dry film resist 13 is laminated on the polyimide film 11 of FIG. 2A. The thickness of the dry film resist 13 can be set in the range of 1 to 200 μmt according to the ratio of the plasma etching rate of the insulating resin to the dry film resist.
A thickness of ~ 150 [mu] mt is preferred. As a method for laminating a dry film, hot roll lamination, vacuum pressure lamination, or the like can be appropriately employed.

In FIG. 2C, the dry film resist 13 is subjected to pattern exposure with ultraviolet rays 18 using a photomask 14 on which a desired pattern is formed.

In FIG. 3D, development is performed with a developer containing an alkali metal such as sodium carbonate and potassium carbonate.

In FIG. 3E, an inorganic acid such as hydrochloric acid or sulfuric acid is used.
Alternatively, the alkali metal adhering to the surface layer of the dry film resist 13 is washed using an organic acid such as bromic acid or citric acid.

As shown in FIG. 4F, the insulating resin layer 11 is etched with the plasma 19 through the opening 20 of the resist 14 (plasma etching process).

In the above, in the plasma etching process, a fluorine-based reaction gas and an oxygen gas are caused to flow at a fixed ratio in a reduced-pressure vacuum vessel, and plasma is generated by applying high-frequency AC power between a cathode and an anode. This is performed by placing an object to be etched in a cathode dark area near the cathode.

Examples of the fluorine-based gas include CF4, CHF
3, C2F6, SF6 and the like can be used. Also,
The atmospheric pressure of oxygen gas and fluorine gas is 0.1
To 100 Pa, preferably 3 to 70 Pa. The introduction amount of oxygen gas and fluorine gas is 1 to
80 SCCM, preferably 10 to 50 SCCM.

The processing power of the plasma discharge is usually 0.1 to
10 W / cm2, preferably 0.7 to 1 W / cm2. As the processing power supply, it is preferable to use a high-frequency AC power supply, and the frequency is 100 kHz to 100 MHz.
z, practically 13.56 MHz of the industrial assigned frequency
It is.

Finally, the resist 14 is peeled off as shown in FIG. An alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be used as the stripping solution. The concentration is 0.1 to 10%, preferably 1 to 5%. The temperature is from room temperature to 80 ° C, preferably 30 to 60 ° C.

[0025]

Embodiments of the present invention will be described below. A wiring pattern was formed using a photolithography method on a laminate in which a copper foil having a thickness of 18 μmt was adhered to the front and back of a polyimide film having a thickness of 25 μmt. After laminating this with SUNFORT (thickness: 50 μmt) of a dry film manufactured by Asahi Kasei Corporation, pattern exposure was performed using a predetermined mask. This was developed using a spray processing apparatus at a liquid temperature of 30 ° C. and a 1% aqueous sodium carbonate solution. Then at room temperature, 5
Then, dip washing was performed with 5% hydrochloric acid for 5 minutes.

Next, the vacuum chamber was set in a vacuum vessel of a dry etching apparatus manufactured by Nippon Vacuum Co., Ltd., and the pressure in the vacuum vessel was reduced.
After reaching 001 Pa, a mixed gas of oxygen and CF4 (volume ratio of 4: 1) was introduced, and then 50 cc / m.
Introduce at the flow rate of in. Maintaining the total gas pressure at 50 Pa,
Plasma discharge was performed at a discharge power of 400 W and a frequency of 13.56 MHz, and the surface of the polyimide resin layer and the patterned dry film were subjected to plasma etching for 40 minutes. The remaining dry film resist was peeled and removed with a 2% aqueous sodium hydroxide solution, and it was confirmed that the polyimide film was processed into a desired pattern.

[0027]

According to the present invention, the effects obtained by using an acrylic dry film resist as a resist for plasma etching are inexpensive, flexible, and easy to handle. In addition, by using a fluorine-based gas having high dry etching reactivity, the etching rate of the insulating resin in dry etching can be increased. In addition, since the pickling treatment also reduces the residual etching failure of the insulating resin, it contributes to improvement in productivity and yield and is advantageous in cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an outline of a processing procedure according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a processing material and the like according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of development and the like according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of plasma etching and the like according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a new problem such as plasma etching according to the embodiment of the present invention.

[Explanation of symbols]

11: Polyimide film 12: Wiring 13: Dry film resist 14: Patterned dry film resist mask 15: Surface layer of dry film resist with alkali metal adsorbed 16: Fluoride salt 17: Unetched portion of insulating resin 18: Ultraviolet 19: Plasma 20: Opening

Claims (6)

[Claims] A first step of forming a dry film resist layer having a desired pattern shape on a wiring board in which a circuit pattern of a metal conductor layer is formed on an insulator layer; A method of processing a wiring board, comprising: a second step of removing an insulator layer from a layer opening by a plasma etching process; and a third step of peeling and removing the resist layer. 2. The wiring board according to claim 1, wherein a developing solution containing an alkali metal is used as a developing solution for the resist layer, and a washing step with an acid is performed after the developing process. Processing method. 3. The method according to claim 1, wherein said resist layer is an acrylic alkali-developing dry film resist. 4. The method according to claim 1, wherein the reaction gas used in the plasma etching in the second step is a fluorine-based compound. 5. A step of forming a resist layer on a wiring board having a circuit pattern of a metal conductor layer formed on an insulator layer;
Exposing the resist layer on the wiring board through a mask having a desired pattern shape, developing the resist layer to form a desired pattern shape, performing an acid treatment, and performing the resist in a plasma etching process. A method for processing a wiring board, comprising: a step of removing an insulator layer from an opening where a layer is not formed; and a step of peeling and removing the resist layer. 6. A step of forming a dry film resist layer on a wiring board on which a circuit pattern of a metal conductor layer is formed on an insulator layer, and using the dry film resist layer on the wiring board with a mask having a desired pattern shape. Exposure step, developing the resist layer to form a desired pattern shape, performing an acid treatment, and forming the resist layer in a plasma etching process in which a reactive gas is a fluorine compound. Removing the insulator layer from the opening, and removing and removing the resist layer,
And a method for processing a wiring board.