TW202408335A - Method for producing printed wiring board - Google Patents

Abstract

After laminating an insulation layer (14) and an electrolytic copper foil (15) in this order on an inner layer board (13), a resist pattern (17B) is formed on the electrolytic copper foil (15). Next, using the resist pattern (17B) as an etching resist, the electrolytic copper foil (15) is etched using an etching liquid containing sulfuric acid and hydrogen peroxide, and a mask for via hole formation (18) is formed. Subsequently, the resist pattern (17B) is removed, the part of the insulation layer (14) not covered by the mask for via hole formation (18) is removed using a laser, and via holes (14A) are formed.

Description

Manufacturing method of printed wiring board

The present invention relates to a method of manufacturing a printed wiring board with through holes.

In recent years, in addition to the miniaturization and high performance of semiconductor elements, it has also become difficult to achieve high density and multi-layering of printed wiring boards on which semiconductor elements are mounted, as well as smaller diameters and higher precision of via holes. Or missing. In printed wiring boards, for example, lasers are used to form through-holes in a build-up process, and the thickness is gradually reduced. As a method of forming a through hole using a laser, for example, the following method can be cited. First, an insulating layer and an electrolytic copper foil are formed on the inner substrate with the inner circuit formed in this order. A photoresist layer is placed on the surface of the electrolytic copper foil, exposed and developed to form the part where the through hole has been removed. photoresist pattern. Next, this photoresist pattern is used as an etching resist to etch the electrolytic copper foil to form a through-hole forming mask, and then use laser to remove the portion of the insulating layer that is not covered by the through-hole forming mask to form a through hole. As an etching liquid when etching electrolytic copper foil, for example, a copper (II) chloride aqueous solution can be used (for example, refer to Patent Document 1). [Prior technical literature] [Patent Document]

[Patent Document 1] International Publication No. WO2018/026004

[Technical problem to be solved by the invention]

However, if the electrolytic copper foil is etched with a copper (II) chloride aqueous solution, the etching amount is large and is not easily affected by the opening diameter of the photoresist pattern. The opening diameter of the photomask for forming the through hole will become larger, making it difficult to perform the etching process. Problems with small diameter drilling of through holes.

The present invention is based on such a problem, and its object is to provide a method for manufacturing a printed wiring board that enables small-diameter drilling. [Technical means]

The present invention is described below. [1] A method for manufacturing a printed wiring board, which is characterized by comprising: on an inner substrate formed with an inner circuit, laminating an insulating layer and an electrolytic copper foil in this order to form a multilayer board; The step of setting a photoresist layer on the foil, exposing and developing it to form a photoresist pattern that has removed the part where the through hole is formed; after forming the photoresist pattern, use the photoresist pattern as an etching resist, using a photoresist layer containing sulfuric acid and peroxide. The steps of etching the electrolytic copper foil with a hydrogen etching solution to form a photomask for forming a through hole; the step of removing the photoresist pattern after forming the photomask for forming the via hole; and after removing the photoresist pattern, using a laser The step of removing the portion of the insulating layer that is not covered by the photomask for forming a through hole to form a through hole. [2] The manufacturing method of a printed wiring board according to [1], characterized by including a step of removing residue after forming the photoresist pattern and before forming the through-hole forming mask. [3] The manufacturing method of a printed wiring board according to [1] or [2], characterized in that the etching rate of the etching liquid is 0.5 μm･m/min to 20 μm･m/min. [4] The method for manufacturing a printed wiring board according to [1] or [2], wherein the etching solution contains 0.1w/v% to 10w/v% hydrogen peroxide and 0.5w/v sulfuric acid. %~9w/v%. [5] The manufacturing method of a printed wiring board according to [1] or [2], characterized in that the etching liquid contains 0.1 w/v% to 5 w/v% of alcohol. [6] The method for manufacturing a printed wiring board according to [1] or [2], characterized in that the etching liquid contains azoles or salts thereof. [7] The method for manufacturing a printed wiring board according to [6], wherein the azole is a heterocyclic compound having a five-membered heterocyclic ring having two nitrogen atoms or a condensed heterocyclic ring thereof. [8] The method for manufacturing a printed wiring board according to [7], wherein the azoles are at least one selected from the group consisting of pyrazoles, imidazoles, and benzimidazoles. [9] The method for manufacturing a printed wiring board according to [8], wherein the azole is selected from the group of compounds represented by the following general formula (1), (2), or (3) At least one of: [Chemification 1] [In the above general formula (1), (2) or (3), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom or an alkane having 1 to 6 carbon atoms. group, aryl group with 6 to 10 carbon atoms, carboxyl group, alkyl group with 1 to 6 carbon atoms, nitro group, hydroxyl group, carboxylic acid ester with 2 to 7 carbon atoms, or halogen atom]. [10] The method for manufacturing a printed wiring board according to [1] or [2], characterized in that the etching liquid contains glycol ethers. [11] The method for manufacturing a printed wiring board according to [1] or [2], characterized in that the etching liquid contains halide ions. [12] The method for manufacturing a printed wiring board according to [11], wherein the halide ion is a chloride ion. [13] A method for manufacturing a printed wiring board, which is characterized by comprising: on an inner substrate formed with an inner circuit, laminating an insulating layer and an electrolytic copper foil in this order to form a multilayer board; The steps of arranging a photoresist layer on the foil, exposing and developing it to form a photoresist pattern in which the through-hole portion has been removed; the steps of removing the residue after forming the photoresist pattern; and using the photoresist pattern as the photoresist pattern after removing the residue. Etching resist: the step of etching the aforementioned electrolytic copper foil using an etching solution to form a photomask for forming a through hole; the step of removing the aforementioned photoresist pattern after forming the aforementioned photomask for forming the through hole; and after removing the aforementioned photoresist pattern, The step of removing the portion of the insulating layer that is not covered by the photomask by laser to form a through hole. [Effects of the invention]

According to the present invention, when the electrolytic copper foil is etched to form a photomask for forming a through hole, the etching liquid containing sulfuric acid and hydrogen peroxide can be used, so that the etching amount can be reduced. Therefore, it becomes easily affected by the opening diameter of the photoresist pattern, and the opening diameter of the photomask for forming the through hole can be made smaller, so that the hole diameter of the through hole can be made smaller.

In addition, with the present invention, since the residue will be removed after forming the photoresist pattern, the opening diameter of the photoresist pattern can be made smaller.

Hereinafter, a mode for implementing the present invention (hereinafter referred to as “this embodiment”) will be described in detail. However, the invention is not limited thereto, and various modifications are possible within the scope of the gist.

[First implementation type] 1 to 3 illustrate each step of a method for manufacturing a printed wiring board according to the first embodiment of the present invention. In this embodiment, a method of manufacturing a build-up type multilayer printed wiring board will be described. First, for example, as shown in FIG. 1(A) , a multilayer board 16 (multilayer board) in which the insulating layer 14 and the electrolytic copper foil 15 are laminated in this order is formed on the inner substrate 13 in which the inner circuit 12 is formed on the insulating substrate 11 . formation steps). Specifically, for example, it is formed in the following manner.

The inner substrate 13 can be manufactured by previously known methods. An example of the manufacturing steps of the inner substrate 13 will be described. For example, first, a through hole (not shown) is formed in the insulating substrate 11 made of a glass epoxy-based, polyimide-based, or other resin substrate. The upper and lower surfaces of the insulating substrate 11 and the inner peripheral surface of the through hole are electroplated with copper using electroless copper as a base. Next, a photoresist pattern is formed on the surface, a conductor pattern and a through-hole conductor as the inner layer circuit 12 are formed by etching, and the cavity of the through-hole conductor is filled with plugging resin such as epoxy resin for planarization.

Before laminating the insulating layer 14 and the electrolytic copper foil 15 on the inner substrate 13, it is desirable to roughen the surface of the inner substrate 13, specifically the surface of the inner circuit 12, by etching or the like.

The multilayer board 16 can be formed, for example, by laminating a prepreg material or a resin sheet as the insulating layer 14 on the inner substrate 13, laminating the electrolytic copper foil 15 thereon, and pressing them. Examples of the prepreg material include those in which a fibrous reinforcing material such as glass fiber cloth or carbon fiber is impregnated with a thermosetting resin mixed with additives such as a hardener and a coloring material to form a semi-cured state. Examples of the resin sheet include a thermosetting resin mixed with additives such as a curing agent and a coloring material in a semi-cured state. Examples of the thermosetting resin used for prepregs or resin sheets include polyimide resins, liquid crystal polyesters, epoxy compounds, cyanate ester compounds, maleimide compounds, phenol compounds, polyamide resins, etc. Phenyl ether compounds, benzoxazine compounds, organic modified silicone compounds, and compounds with polymerizable unsaturated groups. The electrolytic copper foil 15 can be laminated, for example, by using an electrolytic copper foil with a carrier and laminating the electrolytic copper foil side as the side of the insulating layer 14 and peeling off the carrier.

In addition, the multilayer board 16 may also be formed by using, for example, a copper foil with a resin layer in which an insulating resin layer is formed on the electrolytic copper foil 15, and the resin layer is used as the insulating layer 14 so that the resin layer is in contact with the inner substrate. 13. Build up layers and press them to form. Examples of materials constituting the resin layer include the same prepregs or resin sheets as described above. Furthermore, in the multilayer board 16, for example, the insulating layer 14 can be formed by coating an insulating liquid resin such as an epoxy resin on the inner substrate 13 with a spin coater or the like and then thermally curing the resin. The electrolytic copper foil 15 is laminated and pressed to form.

The thickness of the insulating layer 14 is, for example, ideally 1 μm to 40 μm. The thickness of the electrolytic copper foil 15 is, for example, ideally 0.5 μm to 20 μm.

Next, for example, as shown in FIG. 1(B) , the surface of the electrolytic copper foil 15 of the multilayer board 16 is roughened by etching or the like (electrolytic copper foil roughening step). Roughening, for example, ideally using a micro-roughening etchant.

Next, for example, as shown in FIG. 1(C) , a dry film photoresist is laminated on the electrolytic copper foil 15 to form the photoresist layer 17 (photoresist layer forming step). At this time, the ideal photoresist layer lamination is 50°C to 140°C, the pressing pressure is 1kgf/cm ² to 15kgf/cm ² , and the pressing time is 5 seconds to 300 seconds. Next, for example, as shown in FIGS. 1(D) and 1(E) , the photoresist layer 17 is exposed in this order in such a manner that only parts other than the through holes 14A formed in the subsequent steps remain (FIG. 1(D) )) and development (Fig. 1(E)) to form the photoresist pattern 17B from which the portion (via hole forming portion) 17A where the via hole 14A is formed is removed (photoresist pattern forming step).

In the exposure step, a designated portion of the photoresist layer 17 is irradiated with active energy rays to harden the irradiated portion. The active energy rays can be irradiated through a mask pattern, or a direct drawing method of directly irradiating active energy rays can be used. Examples of active energy rays include ultraviolet rays, visible rays, electron rays, and X-rays, and ultraviolet rays are particularly preferred. The exposure amount of ultraviolet rays is approximately 10mJ/cm ² ~1000mJ/cm ² . In addition, for example, the opening diameter of the photoresist pattern 17B can be made smaller by making the design value of the aperture of the photoresist pattern 17B smaller.

Development is not particularly limited as long as only the unexposed portion can be eluted, and a developer such as an alkaline aqueous solution, an aqueous developer, and an organic solvent can be used. As the development method, for example, conventional methods such as spraying, shaking dipping, brushing, and scraping can be used.

After the photoresist pattern 17B is formed, for example, as shown in FIG. 2(F) , the scum (photoresist scum) is ideally removed by plasma cleaning (scum removal step). This is because in the photoresist pattern forming step, if the exposure conditions are adjusted to reduce the opening diameter of the photoresist pattern 17B, in the subsequent steps, when the electrolytic copper foil 15 is etched to form the through-hole forming mask 18, residues This will have a greater impact on the aperture deviation of the through-hole forming mask 18 .

After removing the residue, for example, as shown in FIG. 2(G) , the electrolytic copper foil 15 is etched using the photoresist pattern 17B as an etching resist to form a through-hole forming mask 18 (through-hole forming mask forming step). As an etching method, for example, conventional methods such as spraying and shaking dipping can be used. As an etching solution, it is ideal to use one containing sulfuric acid and hydrogen peroxide. The etching solution using sulfuric acid and hydrogen peroxide has a lower etching rate than a copper (II) chloride aqueous solution and a small etching amount. It is easily affected by the opening diameter of the photoresist pattern 17B. The opening of the photomask 18 can be used to form the through hole. Smaller diameter.

The etching solution for electrolytic copper foil 15 ideally contains water as the main active ingredient and contains sulfuric acid and hydrogen peroxide. For example, the content of sulfuric acid and hydrogen peroxide is ideally hydrogen peroxide 0.1w/v% (mass volume %)~ 10w/v%, sulfuric acid 0.5w/v%~9w/v%, more ideally hydrogen peroxide 0.15w/v%~6.00w/v%, sulfuric acid 0.75w/v%~8.50w/v%, even more ideally It is hydrogen peroxide 0.20w/v%~3.00w/v% and sulfuric acid 1.00w/v%~8.00w/v%. Because better results can be obtained in this range. The etching solution for the electrolytic copper foil 15 preferably contains 0.1w/v% to 5w/v% of alcohol as an additive. Because alcohol has the function of being a stabilizer for hydrogen peroxide and a glossing agent for copper. Examples of alcohols include monohydric alcohols such as methanol, ethanol, propanol, and butanol; dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, and pentanediol; and trihydric alcohols such as glycerin and neopentyl erythritol. For alcohols with an alcohol content of 0.0 or more, one type of these alcohols may be used or two or more types may be mixed and used. The etching solution for the electrolytic copper foil 15 can be prepared by a conventional method, or a commercially available product can be used. Examples of commercially available etching solutions for the electrolytic copper foil 15 include etching solutions manufactured by Mitsubishi Gas Chemical Co., Ltd. such as SE-07, CPE-770, CPE-770D, and CPE-800.

The etching solution for the electrolytic copper foil 15 ideally has an etching rate of 0.5μm･m/min~20μm･m/min, more preferably 0.6μm･m/min~17μm･m/min, and even more preferably 0.7μm･m. /min~15μm･m/min. Because better results can be obtained in this range.

In addition, the etching solution for the electrolytic copper foil 15 preferably contains azoles or salts thereof in addition to sulfuric acid and hydrogen peroxide. This is because the azoles or their salts have the function of being adsorbed on the surface of the electrolytic copper foil 15, thereby making the width difference between the top and the bottom of the opening of the through-hole forming photomask 18 smaller. As the azole, a heterocyclic compound having a five-membered heterocyclic ring having two nitrogen atoms or a condensed heterocyclic ring thereof is ideal. Desirable examples of the azoles include at least one selected from the group consisting of pyrazoles, imidazoles, and benzimidazoles. More specifically, the azoles are preferably selected from the group consisting of the following general formulas (1) and (2). , or at least one of the group of compounds shown in (3). The content of azoles, for example, based on the total amount of the etching liquid (mass basis), is ideally within the range of 0.01 to 0.5 mass % (100 to 5000 ppm), more preferably 0.05 to 0.4 mass % (500 to 4000 ppm), and more preferably Ideal is 0.1~0.3% by mass (1000~3000ppm), particularly ideally is 0.15~0.25% by mass (1500~2500ppm). By setting the azole content within the above range, the width difference between the top and bottom of the opening of the through-hole forming mask 18 can be made smaller. In addition, when a salt of an azole is used, the content of the azole is calculated by converting it into the content of the azole excluding the salt. When two or more components are used, it is sufficient as long as the total amount of the azoles contained in them is within the above range.

〔Chemical 2〕 (In the above general formula (1), (2) or (3), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom or an alkane having 1 to 6 carbon atoms. group, aryl group with 6 to 10 carbon atoms, carboxyl group, alkyl group with 1 to 6 carbon atoms, nitro group, hydroxyl group, carboxylic acid ester with 2 to 7 carbon atoms, or halogen atom.)

Furthermore, the etching solution for the electrolytic copper foil 15 ideally contains glycol ethers in addition to sulfuric acid and hydrogen peroxide. Glycol ethers have the effect of making the amount of electrolytic copper foil 15 dissolved in the etching process uniform. Specifically, the etching rate and etching amount of the electrolytic copper foil 15 can be made uniform during the etching process. Therefore, it is possible to achieve a uniform opening shape of the through-hole forming mask 18 . Examples of glycol ethers include at least one selected from the group consisting of ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monophenyl ether, and dipropylene glycol monomethyl ether. The content of glycol ethers, for example, based on the total amount of the etching solution (mass basis), is ideally within the range of 0.01 to 1 mass % (100 to 10000 ppm), and more preferably 0.05 to 0.75 mass % (500 to 7500 ppm). , more ideally 0.1~0.5% by mass (1000~5000ppm). By setting the content within the above range, the etching rate and etching amount of the electrolytic copper foil 15 can be made more uniform. In addition, according to an ideal aspect of the present invention, the content is within the above range, thereby making it less susceptible to the influence of physical conditions such as spray pressure during etching. When two or more components are used, it is sufficient as long as the total amount is within the above range.

In addition, the etching solution for the electrolytic copper foil 15 ideally contains halide ions in addition to sulfuric acid and hydrogen peroxide. Because halide ions have the effect of stabilizing the etching rate. An ideal halide ion is, for example, a chloride ion. The content of halide ions is, for example, in the range of 0.01 to 3 ppm based on the total amount of the etching liquid (mass basis), preferably 0.05 to 2 ppm, and more preferably 0.1 to 1 ppm. By setting the content within the above range, the etching rate can be made more stable. When two or more halide ions are used, the total amount of components derived from them may be within the above range.

After the via hole forming mask 18 is formed, for example, as shown in FIG. 2(H) , the photoresist pattern 17B is removed (photoresist pattern removal step). After the photoresist pattern 17B is removed, for example, as shown in FIG. 2(I) , the portion of the insulating layer 14 that is not covered by the through-hole forming mask 18 is removed by a laser such as a CO ₂ laser to form the through hole 14A ( Via forming step). The laser processing of the through hole 14A continues until the conductor pattern under the insulating layer 14 is exposed.

After the through hole 14A is formed, for example, as shown in FIG. 3(J) , the smear (resin residue) in the through hole 14A is removed (smear removal step). After the smear is removed, for example, as shown in FIG. 3(K) , the through-hole conductor 19 is formed in the through-hole 14A, and the conductor pattern 20 is formed on the insulating layer 14 (through-hole conductor and conductor pattern forming step). Specifically, for example, the through-hole conductor 19 and the conductor pattern 20 are formed on the through-hole forming mask 18 and the through-hole 14A by electroless copper plating and hole-filled copper plating.

Thereafter, when further overlapping layers, the above-mentioned multilayer board forming steps to the through-hole conductor and conductor pattern forming steps are repeated until the required number of layers is reached.

According to this embodiment, when the electrolytic copper foil 15 is etched to form the through-hole forming mask 18, an etching liquid containing sulfuric acid and hydrogen peroxide is used, so that the amount of etching can be reduced. Therefore, it becomes easy to be affected by the opening diameter of the photoresist pattern 17B, and the opening diameter of the through-hole forming mask 18 can be made smaller, and the aperture diameter of the through-hole 14A can be made smaller.

In addition, since the residue is removed after the photoresist pattern 17B is formed, the opening diameter of the photoresist pattern 17B can be made smaller, the opening diameter of the through-hole forming mask 18 and the aperture diameter of the through hole 14A can be made smaller.

[Second Implementation Type] In the first embodiment, although the residue removal step is performed after forming the photoresist pattern 17B (see FIG. 2(F) ), the photoresist layer 17 may also be exposed during the photoresist pattern forming step. For example, the photoresist layer 17B may be exposed to light. The design value of the aperture of the resist pattern 17B is adjusted to a condition that can stabilize and open the photoresist pattern 17B, and the residue removal step after forming the photoresist pattern 17B is deleted. Since other parts are the same as those in the first embodiment, referring to FIGS. 1 to 3 , the corresponding components are marked with the same symbols, and detailed descriptions of the same parts are omitted. In the second embodiment, similarly to the first embodiment, when the electrolytic copper foil 15 is etched in the through-hole forming photomask formation step, an etching solution containing sulfuric acid and hydrogen peroxide is used, so that the through hole can be formed. By using a smaller opening diameter of the photomask 18, the diameter of the through hole 14A can be made smaller.

[Third Implementation Type] In the first embodiment, an etching solution containing sulfuric acid and hydrogen peroxide is used to etch the electrolytic copper foil 15 in the through-hole forming photomask forming step (see FIG. 2(G) ), but other etching solutions may also be used. Examples of other etching solutions include an etching solution containing hydrochloric acid and copper (II) chloride, a persulfate-based etching solution (an etching solution using persulfate such as ammonium persulfate or sodium persulfate as an oxidizing agent), or an organic etching solution. Acid-based etching liquid (an etching liquid composed of organic acids such as formic acid and weak chelating agents). Since other parts are the same as those in the first embodiment, referring to FIGS. 1 to 3 , the corresponding components are marked with the same symbols, and detailed descriptions of the same parts are omitted. In the third embodiment, the same as the first embodiment, since the residue removal step is performed after the photoresist pattern 17B is formed, the opening diameter of the photoresist pattern 17B can be made smaller. [Example]

(Example 1) Produce a printed wiring board in the following manner (see Figures 1 to 3).

[Multilayer board formation step] (Refer to Figure 1(A)) As the inner substrate 13, a glass cloth-based BT resin copper-clad laminate (conductor thickness: 12 μm, thickness: 0.1 mm, manufactured by Mitsubishi Gas Chemical Co., Ltd., HL832NS) was prepared, and the surface was roughened. Specifically, first, the inner substrate 13 is washed with a residue remover (CA5330, manufactured by MEC Co., Ltd.) as a pretreatment, and after washing with water, it is washed with a micro-etching agent (CZ8101, manufactured by MEC Co., Ltd. Co., Ltd.) to roughen the copper surface. After washing with water, use anti-rust agent (CL8300, made by Meige Co., Ltd.) to prevent rust and then wash and dry. The etching amount by microetchant is 1μm. The roughening system uses horizontal spraying devices.

After roughening the surface of the inner substrate 13, a 1.5 μm ultra-thin electrolytic copper foil (MTEx, manufactured by Mitsui Mining & Metals Co., Ltd.) with an 18 μm carrier copper foil is placed on the inner substrate 13 (both front and back). Cover thermosetting resin and semi-hardened copper foil with a resin layer (CRS381NSI, manufactured by Mitsubishi Gas Chemical Co., Ltd.), perform lamination molding at a pressure of 3.0 MPa and a temperature of 220°C for 60 minutes, and peel off the attached carrier. The carrier copper foil of the extremely thin electrolytic copper foil of the copper foil forms a multilayer board 16 in which the insulating layer 14 and the electrolytic copper foil 15 are laminated in this order on the inner substrate 13.

[Electrolytic copper foil roughening step] (Refer to Figure 1 (B)) After the multilayer board 16 is produced, the surface of the electrolytic copper foil 15 is roughened using a micro-roughening etchant (EMR-2000, manufactured by Mitsubishi Gas Chemical Co., Ltd.). The roughening conditions were set to a temperature of 30° C. and a copper foil etching amount of 0.5 μm.

[Photoresist layer formation step] (Refer to Figure 1(C)) After the multilayer board 16 is roughened, a dry film photoresist (RY-5107, manufactured by Showa Denko Materials Co., Ltd., thickness 7 μm) is laminated on the electrolytic copper foil 15 to form a photoresist layer 17 . Lamination is performed using equipment manufactured by ONC Co., Ltd. under the conditions of lamination pressure 0.4MPa and lamination temperature 110°C.

[Photoresist pattern formation step] (Refer to Figure 1 (D) (E)) After the photoresist layer 17 is provided, the photoresist layer 17 is exposed. The exposure machine uses INPREX3650 (manufactured by ADTEC Engineering Co., Ltd.) and performs exposure under the conditions of the design value of the photoresist pattern aperture of 9 μm and the exposure amount of 250 mJ. The design value of the photoresist pattern aperture at this time is adjusted to the minimum diameter that can be processed for the opening diameter of the photoresist pattern 17B when the residue removal step is performed after the photoresist pattern forming step. After exposure, the unexposed portion is dissolved by a developer to form a photoresist pattern 17B. A 1% by mass sodium carbonate aqueous solution was used as the developer, and development was performed at a temperature of 30°C and a time of 30 seconds.

[Residue removal step] (Refer to Figure 2(F)) After the photoresist pattern 17B is formed, the residue is removed by plasma cleaning. The device uses a plasma treatment device PCB1600E (manufactured by Nordson Advanced Technology Co., Ltd.), and the gas system uses argon, nitrogen, oxygen, and tetrafluoromethane.

[Mask formation step for via hole formation] (Refer to Figure 2(G)) After removing the residue, the photoresist pattern 17B is used as an etching resist, and the electrolytic copper foil 15 of the multilayer board 16 is removed with an etching solution, washed and dried to form a photomask 18 for forming a through hole. The etching liquid is CPE-770D (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and copper etching is performed at a liquid temperature of 35°C. The device uses a horizontal spray type (manufactured by Tokyo Chemical Industry Co., Ltd.). The liquid composition of etching solution CPE-770D contains water, hydrogen peroxide 2.1w/v%, and sulfuric acid 4w/v%.

[Photoresist pattern removal step] (Refer to Figure 2(H)) After forming the through-hole forming photomask 18, the photoresist pattern 17B is removed. The etching liquid system used R-100S (manufactured by Mitsubishi Gas Chemical Co., Ltd.), and the liquid temperature was set to 48°C. The device uses a spray type (manufactured by Tokyo Chemical Industry Co., Ltd.).

[Through-hole forming step] (see FIG. 2(I) ) After removing the photoresist pattern 17B, the portion of the insulating layer 14 not covered by the through-hole forming mask 18 is removed by CO ₂ laser to form the through-hole 14A. The laser hole processing system uses the ML605GTW4(-P)5350U device (manufactured by Mitsubishi Electric Co., Ltd.).

[Removal step] (Refer to Figure 3(J)) After the through holes 14A are formed, the multilayer board 16 is racked on a plating jig, and is immersed and shaken in a swelling tank, an etching tank, and a neutralizing tank to remove slag. The dipping and shaking system uses the equipment of ALMEX Technology Co., Ltd. The chemical liquid system uses the APPDES process (manufactured by Kamimura Industrial Co., Ltd.). The swelling fluid is APPDES MDS-37, the etching fluid is a mixture of MDE-40 and ELC-SH, and the neutralizing fluid is APPDES MDN-62. The temperature of the etching tank was set to 80°C, and immersion was performed for 10 minutes.

[Through-hole conductor and conductor pattern formation steps] (See Figure 3(K)) After removing the smear, the multilayer board 16 is racked on a plating jig, and an ALMEX that can be immersed and shaken in an electroless copper plating tank is used. Equipment manufactured by Technology Co., Ltd. for electroless copper plating. The chemical solution uses a mixture of THRU-CUP PEA (manufactured by Uemura Industrial Co., Ltd.) and formaldehyde. The temperature of the electroless copper plating solution was set to 36°C and the treatment time was set to 10 minutes to form electroless copper plating with a thickness of 0.4 μm. Next, as hole filling plating, use a dipping type device (manufactured by ALMEX Technology Co., Ltd.), use a phosphorus-containing copper anode as a soluble anode, and plate with a DC current of 1A/ ^dm2 to reach a thickness of 15 μm to form a through hole. Conductor 19 and conductor pattern 20. The temperature of the copper plating bath was set to 22°C, and the leveling agent, brightener, and polymer additives of the perforation filling liquid CU-BRITE TF4 (manufactured by JCU Co., Ltd.) were used. The copper plating bath uses a mixture of copper sulfate, sulfuric acid and hydrochloric acid.

(Example 2) Similar to Example 1, the multilayer board forming step, the electrolytic copper foil roughening step, and the photoresist layer forming step were performed. Next, the exposure conditions are changed, and the photoresist pattern forming step is otherwise carried out in the same manner as in Example 1. The exposure conditions are the same as those in Example 1 except that the design value of the photoresist pattern aperture is set to 11 μm, the exposure amount is 250 mJ, and the adjustment is adjusted to the minimum diameter that can process the opening diameter of the photoresist pattern 17B. Next, the residue removal step is not performed. The rest is the same as in Embodiment 1. The through-hole forming photomask formation step, the photoresist pattern removal step, the through-hole formation step, the sludge removal step, and the through-hole conductor and conductor pattern formation are performed. steps.

(Example 3) The same as in Example 1, the multilayer board forming step, the electrolytic copper foil roughening step, the photoresist layer forming step, the photoresist pattern forming step, and the residue removal step were performed. Next, the etching liquid was changed, and the mask formation step for forming a through hole was performed in the same manner as in Example 1. The etching liquid uses hydrochloric acid and copper (II) chloride aqueous solution. Next, in the same manner as in Embodiment 1, the photoresist pattern removal step, the through hole forming step, the smear removal step, and the through hole conductor and conductor pattern forming steps are performed.

(Comparative example 1) Similar to Example 1, the multilayer board forming step, the electrolytic copper foil roughening step, and the photoresist layer forming step were performed. Next, the exposure conditions are changed, and the photoresist pattern forming step is otherwise carried out in the same manner as in Example 1. The exposure conditions are the same as those in Example 1 except that the design value of the photoresist pattern aperture is set to 11 μm, the exposure amount is 250 mJ, and the adjustment is adjusted to the minimum diameter that can process the opening diameter of the photoresist pattern 17B. Next, the residue removal step was not performed, the etching liquid was changed, and the photomask formation step for forming a through hole was performed in the same manner as in Example 1. The etching liquid uses hydrochloric acid and copper (II) chloride aqueous solution. Next, in the same manner as in Embodiment 1, the photoresist pattern removal step, the through hole forming step, the smear removal step, and the through hole conductor and conductor pattern forming steps are performed.

(Characteristic evaluation) The characteristics of Examples 1 to 3 and Comparative Example 1 were measured by the following method.

[Evaluation of opening diameter of photoresist pattern] After the photoresist pattern 17B is formed, the opening diameter is observed with an electron microscope. The observation system used VE-7800 (manufactured by KEYENCE Co., Ltd.) with the magnification adjusted to 5000 times, and the average value and deviation of the opening diameter were obtained for 10 locations on each sample. The obtained results are shown in Table 1. The average opening diameter of the photoresist pattern 17B was 6.8 μm in Example 1, 8.7 μm in Example 2, 6.8 μm in Example 3, and 8.7 μm in Comparative Example 1.

[Evaluation of opening diameter of photomask for via hole formation] After the via hole forming mask 18 is formed, the opening diameter is observed with an electron microscope in the same manner as the opening diameter of the photoresist pattern is evaluated. The obtained results are also shown in Table 1. The average opening diameter of the through hole forming mask 18 was 8.3 μm in Example 1, 11.4 μm in Example 2, 17.8 μm in Example 3, and 17.5 μm in Comparative Example 1. In addition, the deviation 3σ of the opening diameter of the through-hole forming mask 18 is 1.6 in Example 1, 2.1 in Example 2, 1.2 in Example 3, and 5.1 in Comparative Example 1.

[Evaluation of the top diameter of the through hole] After the through hole 14A is formed, the top diameter is observed with an electron microscope in the same manner as the evaluation of the opening diameter of the photoresist pattern. The obtained results are also shown in Table 1. The average value of the top diameter of the through hole 14A is 16.8 μm in Example 1, 17.4 μm in Example 2, 21.4 μm in Example 3, and 21.7 μm in Comparative Example 1.

〔Table 1〕

As shown in Table 1, in the formation step of the photomask for forming the via hole, according to Examples 1 and 2 in which the etching liquid whose main active ingredients are sulfuric acid and hydrogen peroxide is used, compared with using hydrochloric acid and copper (II) chloride as the etching solution, In Comparative Example 1 of the etching liquid, the opening diameter and the degree of deviation of the through-hole forming mask can be made smaller, and the top diameter of the through-hole 14A can also be made smaller. Furthermore, according to Embodiment 1 in which the residue removal step is performed after forming the photoresist pattern 17B, compared to Embodiment 2 in which the residue removal step is not performed, the opening diameter and the degree of deviation of the through-hole forming mask can be made smaller , the diameter and deviation of the top of the through hole 14A can also be made smaller.

In addition, according to Example 3 in which the residue removal step is performed after forming the photoresist pattern 17B, compared with Comparative Example 1 in which the residue removal step is not performed, the opening diameter of the photoresist pattern can be smaller, and the through hole can be formed using light. The degree of deviation in the opening diameter of the cover is small. [Industrial Applicability]

The present invention can be used to manufacture printed wiring boards.

11:Insulating substrate 12:Inner circuit 13:Inner substrate 14: Insulation layer 14A:Through hole 15:Electrolytic copper foil 16:Multilayer board 17: Photoresist layer 17A: Through hole forming part 17B: Photoresist pattern 18: Mask for through hole formation 19:Through hole conductor 20: Conductor pattern

[Fig. 1] is a diagram showing each step of a method of manufacturing a printed wiring board according to the first embodiment of the present invention. [Fig. 2] is a diagram continuing from Fig. 1 and showing each step. [Fig. 3] is a diagram continuing from Fig. 2 and showing each step.

11:Insulating substrate

12:Inner circuit

13:Inner substrate

14: Insulation layer

14A:Through hole

15:Electrolytic copper foil

16:Multilayer board

17A: Through hole forming part

17B: Photoresist pattern

18: Mask for through hole formation

Claims (13)

A method of manufacturing a printed wiring board, the characteristics of which include: The step of laminating the insulating layer and the electrolytic copper foil in this order on the inner substrate with the inner circuit formed thereon to form a multilayer board; The steps of setting a photoresist layer on the electrolytic copper foil, exposing and developing it, and forming a photoresist pattern with the part where the through hole is formed removed; After the photoresist pattern is formed, the photoresist pattern is used as an etching resist, and an etching solution containing sulfuric acid and hydrogen peroxide is used to etch the electrolytic copper foil to form a photomask for through hole formation; After forming the through-hole forming photomask, the step of removing the photoresist pattern; and After removing the photoresist pattern, use laser to remove the portion of the insulating layer that is not covered by the through-hole forming photomask to form a through-hole. The method of manufacturing a printed wiring board according to claim 1, further comprising a step of removing residue after forming the photoresist pattern and before forming the photomask for forming the through hole. The manufacturing method of a printed wiring board according to claim 1, wherein the etching rate of the etching liquid is 0.5 μm･m/min~20 μm･m/min. The method for manufacturing a printed wiring board according to claim 1, wherein the etching solution contains 0.1w/v%~10w/v% hydrogen peroxide and 0.5w/v%~9w/v% sulfuric acid. The manufacturing method of a printed wiring board according to claim 1, wherein the etching liquid contains alcohol 0.1w/v%~5w/v%. The method for manufacturing a printed wiring board according to claim 1, wherein the etching liquid contains azoles or salts thereof. The method for manufacturing a printed wiring board according to claim 6, wherein the azole is a heterocyclic compound having a five-membered heterocyclic ring with two nitrogen atoms or a condensed heterocyclic ring thereof. The method for manufacturing a printed wiring board according to claim 7, wherein the azoles are at least one selected from the group consisting of pyrazoles, imidazoles, and benzimidazoles. The method for manufacturing a printed wiring board according to claim 8, wherein the azole is selected from at least one type of compounds represented by the following general formula (1), (2), or (3): 1〕 [In the above general formula (1), (2) or (3), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a hydrogen atom or an alkane having 1 to 6 carbon atoms. group, aryl group with 6 to 10 carbon atoms, carboxyl group, alkyl group with 1 to 6 carbon atoms, nitro group, hydroxyl group, carboxylic acid ester with 2 to 7 carbon atoms, or halogen atom]. The method for manufacturing a printed wiring board according to claim 1, wherein the etching liquid contains glycol ethers. The method for manufacturing a printed wiring board according to claim 1, wherein the etching liquid contains halide ions. The method for manufacturing a printed wiring board according to claim 11, wherein the halide ions are chloride ions. A method of manufacturing a printed wiring board, the characteristics of which include: The step of laminating the insulating layer and the electrolytic copper foil in this order on the inner substrate with the inner circuit formed thereon to form a multilayer board; The steps of setting a photoresist layer on the electrolytic copper foil, exposing and developing it, and forming a photoresist pattern with the part where the through hole is formed removed; After forming the photoresist pattern, remove the residue; After removing the residue, use the photoresist pattern as an etching resist, use an etching solution to etch the electrolytic copper foil, and form a photomask for through hole formation; After forming the through-hole forming photomask, the step of removing the photoresist pattern; and After removing the photoresist pattern, use laser to remove the portion of the insulating layer that is not covered by the photomask to form a through hole.