JP2003298205A - Manufacturing method of printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a printed wiring board, by which high quality, high density, and high production yield can be attained although high throughput can be ensured without causing a photoresist removing residue. <P>SOLUTION: In a printed wiring board whose wiring is formed in a process comprising a step for forming a photoresist layer on the surface of a copper alloy plate with a resin, and a step for etching the layer after exposing/ developing the layer, or in a printed wiring board whose wiring is formed in a process comprising a step for forming a photoresist layer on the surface of a conductive frame or a power feed layer, and a step for carrying out electroplating after exposing/developing the layer, the photoresist layer is removed by a chemical treatment process comprising a swelling/removing process and a resist residue removal process. <P>COPYRIGHT: (C)2004,JPO

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.

[0002]

2. Description of the Related Art In recent years, high-density integration and high-density mounting of electronic components have been advanced in response to demands for higher functionality, lighter, thinner, shorter and smaller electronic devices. Due to the demand for light, thin, short, and small printed wiring boards, there is a growing demand for higher-precision processing processes such as higher wiring density and a plurality of wiring layers.

In these printed wiring boards, as a method for forming a wiring pattern, there are generally a method of etching a copper foil (subtractive method), a method of electrolytic copper plating (full semi-additive method) and the like. The subtractive method is characterized in that the height of the formed circuit is defined by the thickness of the copper foil used, and there is an etching limit that depends on the reaction characteristics of the etchant and the capability of the equipment used. It is not suitable for high density and high density. Further, in the semi-additive method, it may be difficult to sufficiently remove the power supply layer by flash etching after forming the wiring layer in the fine pattern region, which causes a problem such as a short circuit due to ion migration between circuits. There was a problem. On the other hand, the full-additive method has begun to receive particular attention because of its merit of being able to deal with free circuit design.

Regardless of which method is applied, it is general that an image of a wiring pattern is formed by an ultraviolet-sensitive alkaline developing photoresist. The photoresist is classified into a dry type and a liquid type, which can be selectively used according to the purpose, but in any state where a wiring pattern image is formed, it is in a solid state. As the wiring becomes finer, these photoresist images also become finer, and therefore improvements have been made to obtain high adhesion to the base even in wet processes such as development, etching and electrolytic plating.

In particular, a photoresist for use in fine wiring is designed to have a high adhesive force, and in some cases, a higher adhesive force may be obtained due to the anchoring effect of the roughening treatment of the underlayer. is there. To remove these photoresists, an aqueous alkali solution containing sodium hydroxide, alcohol amine, tetramethylammonium hydroxide, etc. is usually used in a horizontal transfer spray method. Since the peeling mechanism using an alkaline aqueous solution is usually based on swelling, the shape of the photoresist after peeling is generally in the form of small pieces called peeling pieces. However, it has recently become apparent that the photoresist layer cannot be peeled off due to the finer wiring.
If the peeling residue is present, it can be one of the factors that greatly reduce the process yield such as a defective formation of the insulating layer and a defective removal of the power feeding layer. In the case of the additive method in particular, the photoresist layer is placed in an environment where it is confined between the wiring formed by plating, so if it cannot swell sufficiently or if the wiring overhangs against the photoresist layer, the physical However, there is a problem that the peeling becomes more difficult. To solve this problem, conventionally, the concentration of the alkaline aqueous solution and additives were adjusted so as to make the peeling pieces as small as possible, and the photoresist layer was destroyed by physical force such as high-pressure spray or ultrasonic wave irradiation. However, the current situation is that it has not fully responded to the progress of miniaturization.

Further, when the base is subjected to a roughening treatment, a residue of the photoresist may be generated in a state where it is bitten into the roughening fine irregularities even in a region where the wiring density is relatively low. It is difficult to deal with this problem with an alkaline aqueous solution, and mainly physical force such as high-pressure spray or ultrasonic waves was used, but it was difficult to uniformly remove the residue. In addition, this may cause a problem that a part of the substrate material or the wiring layer itself is destroyed.

Further, it is disclosed that an oxidizing agent is used to prevent peeling residue in photoresist etching (see, for example, Patent Document 1). In many cases, the decomposition rate of the residue of peeling by the oxidizing agent is relatively slow, and there is a problem in complete removal especially when processing a thick film photoresist, and good productivity cannot be obtained. In addition, the insulating resin may dissolve due to long-term oxidant treatment, causing wiring floating.
Problems such as peeling may occur.

[0008]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-217526 (paragraph 2)

[0009]

The present invention provides a method of manufacturing a high-quality, high-density printed wiring board with a high production yield, which does not generate a photoresist peeling residue, even though it is a highly productive processing method. The purpose is to

[0010]

Means for Solving the Problems The inventors of the present invention have carried out a chemical solution treatment step consisting of a swelling peeling step and a resist peeling step in the removal of the photoresist layer in forming a wiring layer of a printed wiring board. The present invention has been completed by finding out that a wiring having a high reliability can be stably obtained without generating a peeling residue and further studying. That is, the present invention provides (1) a printed wiring board in which a wiring is formed by forming a photoresist layer on the surface of a resin-coated copper foil or a resin-coated copper alloy plate, and exposing and developing the film to form a photoresist layer. A method for manufacturing a printed wiring board, characterized in that the removal is performed by a chemical solution treatment step including a swelling and peeling step and a resist residue removing step, and (2) the wiring has a photoresist layer on the surface of the conductive frame or the power feeding layer. A printed wiring board formed by electroplating after forming, exposing, and developing, wherein the removal of the photoresist layer is performed by a chemical solution treatment step including a swelling peeling step and a resist residue removing step. The wiring board manufacturing method (3) swelling and peeling step is performed with an alkaline aqueous solution, and the resist residue removing step is performed with an oxide resin The method for producing a printed wiring board according to the above (1) or (2), which is carried out with a tinging agent or an organic solvent, and (4) treatment with an oxidizing resin etching agent, followed by treatment with a reducing agent. A method for manufacturing a printed wiring board according to the item (3),
(5) The method for producing a printed wiring board according to any one of (1) to (4), wherein the resist residue removing step is performed by applying ultrasonic waves.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing a printed wiring board according to the present invention comprises forming a photoresist layer on the surface of a resin-coated copper foil or a resin-coated copper alloy plate in a wiring formed on a substrate, and exposing and developing it. The present invention can be applied to a subtractive method in which a copper foil or a copper alloy plate is subsequently formed by etching, and an additive method in which a photoresist layer is formed on the surface of a conductive frame or a power feeding layer, and exposure and development are followed by electrolytic plating.

Embodiments of the present invention will be described below, but the present invention is not limited thereto.

As the base material applied to the method for producing a printed wiring board of the present invention, in the subtractive method, a copper foil or a polyimide film with a copper alloy plate used for a flexible printed wiring board or a copper used for a rigid wiring board is used. Examples include glass / epoxy type substrates with foil or copper alloy plate. In the additive method, a conductive frame such as copper or a copper alloy plate may be used, or a power feeding layer such as electroless copper plating may be formed on the insulating resin layer.

As a method of forming the wiring, first, the surface of the base material is subjected to surface treatment such as acid treatment, and then a photoresist layer is formed. Here, the surface treatment liquid can be appropriately selected according to the intended specifications of the printed wiring board. For example,
Examples thereof include sulfuric acid, a mixture of sulfuric acid and hydrogen peroxide water, sodium persulfate, ammonium persulfate, nitric acid, hydrochloric acid, formic acid, and ammonium acid fluoride. Of course, a plurality of combinations may be performed. When the fine wiring is formed by the additive method, it is preferable to perform a roughening treatment so that the anchor effect is obtained and the adhesion of the photoresist layer is improved. The photoresist layer can be used as long as it has photosensitivity and can be patterned, but an alkali-soluble dry film resist is preferable from the viewpoint of productivity and environmental protection.

Next, the photoresist layer is exposed through a mask for exposure in which a predetermined pattern image is drawn and developed.
As the exposure mask, a film mask to which an emulsion silver salt is fixed, a glass mask, a chromium-deposited glass mask, or the like can be used. Further, in the case of an alkali-soluble photoresist layer, for the development, a carbonate of an alkali metal such as lithium, sodium or potassium, or an aqueous solution of hydroxide or an aqueous solution of tetramethylammonium hydroxide can be used. From the viewpoint of cost and environment, an aqueous sodium carbonate solution is usually used.

Next, in the case of the subtractive method, a conductor circuit is formed by etching the copper foil or the copper alloy plate on the base material. For etching, a ferric chloride-based aqueous solution or a cupric chloride-based aqueous solution is usually used, but any acidic chemical solution capable of dissolving and removing the base copper foil or the copper alloy plate can be used. For example, a mixture of sulfuric acid and hydrogen peroxide water, an aqueous solution of sodium persulfate, etc. may be mentioned. On the other hand, in the additive method, conductor wiring is formed on the base material by electrolytic copper plating. At this time, in the case of a conductive frame, plating is performed using this as a power feeding layer. An acidic bath such as a copper sulfate or copper pyrophosphate plating bath is suitable for the copper plating solution.

Next, the photoresist layer is peeled off by a two-step chemical treatment process including a swelling peeling process and a resist residue removing process. First, in the swelling and peeling step, it is most preferable to use an alkaline aqueous solution, which is inexpensive and has a high effect of swelling and fragmenting the photoresist, for the chemical treatment. Examples include alkali metal hydroxide aqueous solutions, carbonate aqueous solutions, amine aqueous solutions, and the like. Specific examples of the alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, and carbonates. Examples of salts include lithium carbonate, sodium carbonate and potassium carbonate, and examples of amines include ethanolamine and tetramethylammonium hydroxide. Of course, a plurality of these may be mixed and used. Further, as the treatment method used in the swelling and peeling step, a horizontal transfer type spray device, an immersion type device, a rack type immersion device, or the like can be appropriately selected and used according to the form of the substrate.

Next, after passing through a water washing step, a chemical treatment in a resist residue removing step is performed to completely remove minute resist residues generated in the swelling and peeling step. In the resist residue removing step, the chemical liquid used is preferably one that can dissolve the photoresist. For example, oxidizing resin etching agents, organic solvents and the like, specifically, as the oxidizing resin etching agent, lithium permanganate, sodium permanganate, potassium permanganate, lithium dichromate, sodium dichromate, Organic solvents such as potassium dichromate, dimethyl ketone, diethyl ketone, methyl ethyl ketone, dimethyl sulfoxide,
N-methyl-2-pyrrolidone and the like. These can be used alone, or a plurality of them may be mixed and used.
Since the rate of resin dissolution by an oxidizing resin etching agent or an organic solvent is relatively slow, it is advantageous from the viewpoint of productivity to remove the resist as much as possible in the first stage as a two-stage stripping method. Further, in the second step of the oxidizing resin etching agent treatment, the surface of the circuit copper may be oxidized, so that it is most preferable to perform the reduction treatment with an acidic amine aqueous solution or the like. This is because the alkaline residue component derived from the oxidizing resin etching agent can be neutralized and removed at the same time by treating with an acidic amine aqueous solution. Examples thereof include hydroxylamine hydrochloride and hydroxylamine sulfate. As a method of chemical treatment in the resist residue removing step, a horizontal transfer type or rack type spray device, an immersion type device, etc. can be appropriately selected and used according to the form of the substrate. Further, in the dipping process using the dipping type device, the resist residue can be removed more completely by applying ultrasonic waves. At this time, although problems such as damage due to ultrasonic waves may be considered for fine wiring, it is possible to easily avoid it by controlling the output and frequency. This condition is appropriately adjusted and applied according to the wiring rule, the adhesion between the wiring and the base, the viscosity of the chemical solution used, etc., and is not particularly limited.

Next, a solder resist and an insulating layer are formed to obtain a printed wiring board according to the method for producing a printed wiring board of the present invention.

[0020]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1 A double-sided copper-clad laminate 101 having a total thickness of 0.3 mm and a copper foil thickness of 12 μm (FIG. 1 (a))
(ELC-4781 manufactured by Sumitomo Bakelite Co., Ltd.) is used to perform a subtractive process (not shown) to form a two-layer wiring inner layer conductor circuit 10 having a minimum line width / line spacing of 50/50 μm.
2 was manufactured (FIG. 1 (b)). Next, the inner conductor circuit 102
Roughening is performed by spraying a chemical solution containing hydrogen peroxide and sulfuric acid as main components (Tech SO-G manufactured by Asahi Denka Kogyo Co., Ltd.) on the surface to form a dry film type 25 μm thick film. A thermosetting interlayer insulating resin (AT-3001 manufactured by Sumitomo Bakelite Co., Ltd.) was used to bury wiring using a vacuum laminator, and a baking treatment was performed at 150 ° C. for 30 minutes to form an insulating resin layer 103 (FIG. 1). (C)). Next, a blind via hole 104 having a diameter of 40 μm was formed using a UV-YAG laser device (ML605LDX manufactured by Mitsubishi Electric Corporation) (see FIG. 1).
(D)), after performing desmear treatment (McDuizer series manufactured by MacDermid Japan Co., Ltd.), electroless copper plating (Sulcup PRX manufactured by Uemura Kogyo Co., Ltd.) is performed for 15 minutes to form a power feeding layer having a thickness of 0.5 μm. 105 (FIG. 2)
(E)). Next, a 25 μm thick UV-sensitive dry film 106 (AQ manufactured by Asahi Kasei Corp.) was formed on the surface of the power feeding layer.
(2558) are pasted together by a hot roll laminator, and a chromium vapor deposition mask (manufactured by Towa Process Co., Ltd.) on which a pattern having a minimum line width / line spacing of 20/20 μm is drawn
2) was used for alignment (FIG. 2 (f)), and exposure was performed using an exposure device (UX-1100SM-AJN01 manufactured by USHIO INC.). It was developed with an aqueous solution of sodium carbonate to form a plating resist 107 (FIG. 2 (g)).

Next, electrolytic copper plating (81-HL, Okuno Seiyaku Co., Ltd.) was used at 3 A / dm ² , 3 with the power feeding layer 105 as an electrode.
After 0 minutes, a copper wiring 108 having a thickness of about 20 μm was formed (FIG. 3 (h)). Here, using the two-step stripper consisting of the treatment steps as shown in FIG.
07 was peeled off. Each chemical solution contains a monoethanolamine solution (Mitsubishi Gas Chemical Co., Ltd.) in the first-stage alkaline aqueous solution layer.
R-100 manufactured by R-100), and an aqueous solution containing potassium permanganate and sodium hydroxide as main components for the second-stage oxidative resin etching agent (Mccudizer 9275, 9276 manufactured by Nippon Macdermid Co., Ltd.), and acidic for neutralization. Amine aqueous solution (McDuizer 927 manufactured by Nippon MacDermid Co., Ltd.
9) was used respectively.

Next, the power supply layer 105 was immersed in an aqueous solution of ammonium persulfate (AD-485 manufactured by Meltex Co., Ltd.) to remove it by etching to ensure insulation between wirings (FIG. 3 (i)). Finally, a dry film type solder resist 109 (CFP-1121 manufactured by Sumitomo Bakelite Co., Ltd.) was formed on the circuit surface while the circuit was embedded by a vacuum laminator (FIG. 3 (j)).

(Embodiment 2) The peeling of the etching photoresist when the inner layer conductor circuit 102 is manufactured by the subtractive method comprises the processing steps as shown in FIG.
A substrate was prepared in the same manner as in Example 1 except that the step-separator was used.

Example 3 A dimethylsulfoxide-based alkaline solvent (JSR) was used in the second stage of the two-stage peeling machine.
A substrate was manufactured in the same manner as in Example 1 except that THB-S1 manufactured by Co., Ltd. was used.

(Embodiment 4) An ultrasonic wave generator (C) is provided in the second stage of the two-stage peeling machine having the treatment steps shown in FIG.
A 4G-500-6T manufactured by REST Co., Ltd. was installed, and a substrate was manufactured in the same manner as in Example 1 except that ultrasonic waves were applied during the second stage immersion treatment under the conditions of a frequency of 40 kHz and an output of 200 W. did.

(Comparative Example 1) Example 1 was repeated except that the conventional peeling method was one-step peeling and an aqueous sodium hydroxide solution was used.
A substrate was manufactured in the same manner as in.

Comparative Example 2 A substrate was manufactured in the same manner as in Example 1 except that the conventional peeling method was one-step peeling and the aqueous solution containing potassium permanganate and sodium hydroxide as main components was used.

Comparative Example 3 A substrate was manufactured in the same manner as in Example 1 except that the conventional one-step peeling method was used and a dimethylsulfoxide-based alkaline solvent was used.

The evaluation items, methods and results will be described in detail below. Observation of peeling residue The space between the circuits of the build-up layer of each substrate obtained above was observed with a scanning electron microscope. The presence or absence of residues is summarized in Table 1. 2. Measurement of time required for peeling process 1. The minimum time at which no peeling residue was generated was measured in Table 1 and summarized in Table 1. 3. Insulation resistance test After measuring the initial insulation resistance of each substrate obtained above,
A DC voltage of 5.5 V was applied in an atmosphere of 5 ° C./85% relative humidity, and the insulation resistance after 1000 hours was measured. The applied voltage at the time of measurement was 100 V for 1 minute, and the initial insulation resistance and the post-treatment insulation resistance are summarized in Table 1.

[0031]

[Table 1]

As can be seen from the evaluation results shown in Table 1,
The printed wiring board manufactured by the method for manufacturing a printed wiring board of the present invention can be subjected to a peeling treatment in a short time without generation of a photoresist peeling residue. Also,
Since no peeling residue was generated, no decrease in insulation reliability due to copper migration between wirings was observed. on the other hand,
In each of the substrates manufactured in Comparative Example, a peeling residue of the photoresist was generated or it took a long time to completely remove the photoresist. When a peeling residue was generated, insulation failure between wirings was confirmed in the insulation reliability test. As described above, according to the method for manufacturing a printed wiring board of the present invention, the photoresist can be completely removed in a relatively short time, and a substrate having high insulation reliability between wirings can be obtained.

[0033]

According to the present invention, it is possible to provide a method for producing a high-quality, high-density printed wiring board with a high production yield, which does not generate a photoresist peeling residue, by a highly productive processing method.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a method for manufacturing a printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of the method for manufacturing a printed wiring board of the present invention (sequel to FIG. 1).

FIG. 3 is a cross-sectional view showing an embodiment of the method for manufacturing a printed wiring board of the present invention (sequel to FIG. 2).

FIG. 4 is a process flow diagram of a two-step peeling machine used in the method for manufacturing a printed wiring board of the present invention.

[Explanation of symbols]

101 Double-sided copper-clad laminate 102 Inner layer conductor circuit 103 Insulating resin layer 104 Blind Via Hall 105 power supply layer 106 UV-sensitive dry film 107 Plating resist 108 copper wiring 109 Solder resist

Claims (5)

[Claims] 1. A printed wiring board in which a wiring is formed by forming a photoresist layer on the surface of a resin-coated copper foil or a resin-coated copper alloy plate, and then etching and then exposing, developing, and removing the photoresist layer causes swelling. A method of manufacturing a printed wiring board, which is performed in a chemical treatment process including a peeling process and a resist residue removing process. 2. In a printed wiring board in which a wiring is formed by forming a photoresist layer on the surface of a conductive frame or a power feeding layer and then performing electroplating after exposure and development, the removal of the photoresist layer includes a swelling and peeling step. And a resist residue removing step, which is performed in a chemical treatment step. 3. The swelling and peeling step is performed with an alkaline aqueous solution, and the resist residue removing step is performed with an oxide resin etching agent or an organic solvent.
A method for manufacturing a printed wiring board according to. 4. The method for manufacturing a printed wiring board according to claim 3, wherein the treatment with the oxidizing resin etching agent is followed by the treatment with the reducing agent. 5. The method for manufacturing a printed wiring board according to claim 1, wherein the resist residue removing step is performed by applying ultrasonic waves.