KR20130099093A

KR20130099093A - Method for forming solder resist pattern

Info

Publication number: KR20130099093A
Application number: KR1020137008986A
Authority: KR
Inventors: 유지 도요다; 노리히코 고칸; 무네토시 이리사와; 야스오 가네다; 구니히로 나카가와
Original assignee: 미쓰비시 세이시 가부시키가이샤
Priority date: 2010-09-28
Filing date: 2011-09-05
Publication date: 2013-09-05
Also published as: CN103109588B; JP5871396B2; JP2016048786A; KR101891949B1; KR101891840B1; CN103109588A; JPWO2012043201A1; JP6124372B2; KR20180075697A; WO2012043201A1

Abstract

A step of forming a solder resist layer on the surface of the circuit board having the connection pad, and a step of thinning until the thickness of the solder resist layer is less than or equal to the thickness of the connection pad by an aqueous alkali solution, It is a formation method of the soldering resist pattern which does not have an electrical short circuit by the solder between the connection pads for semiconductor connection which adjoins mutually, and does not leave a soldering resist residue on a connection pad.

Description

Method of Forming Solder Resist Pattern {METHOD FOR FORMING SOLDER RESIST PATTERN}

A method of forming a solder resist pattern.

In order to prevent the solder from adhering to the wiring pattern which is unnecessary for soldering, the solder resist pattern on the circuit board inside the various electrical devices is formed on the entire surface of the part other than the soldering part, and the oxidation prevention of the conductor and the electrical insulation And protection from the external environment.

In a semiconductor package in which electronic components such as semiconductor chips are mounted on a circuit board, mounting by flip chip connection is an effective means for achieving high speed and high density. In flip chip connection, a part of the conductor wiring of a circuit board is used as a connection pad for flip chip connection, and the solder bump arrange | positioned on this connection pad and the electrode terminal of a semiconductor chip are joined, for example.

1-5 is a schematic cross-sectional structural view of the soldering resist pattern which covered the soldering resist layer other than the part (for example, connection pad) to solder on a circuit board. 1 is a schematic cross-sectional structural view of a solder mask defined (SMD) structure, wherein an opening of the solder resist layer 3 is smaller than that of the connection pad 6. 2 to 5 are schematic cross-sectional structural views of the Non Solder Mask Defined (NSMD) structure, wherein an opening of the solder resist layer 3 is greater than or equal to the connection pad 6.

As a method of forming a soldering resist pattern, the photolithography system is generally known. In the photolithography method, after forming the soldering resist layer 3 on the circuit board which has the connection pad 6 and the conductor wiring 2 on the insulating substrate 1, the connection pad 6 is exposed and developed. The peripheral solder resist layer 3 is completely removed to form an opening. With this photolithography system, only the structures of Figs. 1, 2 and 3 can be produced so far.

As shown in Fig. 2, in the case where no solder resist layer is present between the connection pads 6, when the pitch between the connection pads is narrowed, the plating shorts between the connection pads during the electroless nickel / gold plating performed prior to the soldering. (Iii) occurs. Even when the solder resist layer 3 is present between the connection pads 6, when the solder resist layer 3 is thick as shown in Figs. 1 and 3, they are disturbed and the electronic components cannot be mounted correctly. There is a problem. In addition, with the recent miniaturization and multifunctionalization of electronic devices, when the connection pads are less than 50 µm, it is very difficult to produce the structures of FIGS. 1 and 3 by photolithography in terms of positional shift of exposure. It was. For this reason, as shown in FIG. 4 and FIG. 5, the structure whose thickness of the soldering resist layer 3 between the connection pads 6 is below the thickness of the connection pad 6 is calculated | required.

In the structure of FIG. 4, a solder resist pattern having a slit-shaped opening is formed by a wet blasting method, and exposes a plurality of connection pads 6 formed in parallel with each other. It is a structure in which the soldering resist layer 3 of the same height as the connection pad 6 is filled between 6). This structure is a soldering resist layer which carried out ultraviolet curing and heat curing after coating the soldering resist layer 3 on the circuit board which has the connection pad 6 and the conductor wiring 2 on the insulating substrate 1 ( 3) After forming a resin layer for forming a mask for wet blast on, exposure and development are carried out to form a patterned wet blast mask, and then wet blasting to form a slit-like opening in the solder resist layer. It is formed by removing the mask for wet blast (for example, refer patent document 1).

In addition, a connection pad is exposed to a circuit board having a connection pad and a conductor wiring having a height lower than that of the connection pad, the conductor wiring is covered by a solder resist layer, and a solder resist layer having the same height as the connection pad between the connection pads. This filled structure is also disclosed (for example, refer patent document 2). This structure is formed by coating a soldering resist layer on the circuit board which has a connection pad and conductor wiring lower than a connection pad, and then grinds until the upper surface of a connection pad is exposed. As the polishing method, a mechanical polishing method or a laser scribing method can be employed.

In the structure of FIG. 5, although the soldering resist layer 3 exists between the connection pads 6, the outer peripheral surface of the connection pad 6 is exposed. The structure of FIG. 5 electroless-nickel-plats the whole connection pad 6, it coat | covers with a nickel layer, after coating the soldering resist layer 3 on conductor wiring, it performs ultraviolet curing and heat-hardening, and a soldering resist It is formed by exposing the upper surface of the nickel layer by blast-polishing the layer 3, and removing a nickel layer by etching after that (for example, refer patent document 3).

In the methods of Patent Documents 1 to 3, polishing methods such as wet blasting and mechanical polishing are used to form the openings of the solder resist layer. Processing with high precision to completely expose the upper surface without leaving a residue of the solder resist layer on the pad was very difficult. Moreover, although it is easy to make the height of a soldering resist layer and a connection pad the same, when trying to make the height of a soldering resist layer lower than a connection pad, in a grinding | polishing process, a scratch or a defect generate | occur | produce in other parts including a connection pad. There was a problem.

As a method of removing a soldering resist layer, there also exists a method of decomposing | disassembling unnecessary soldering resist by laser irradiation, but there existed a problem of a complicated process and a productivity fall (for example, refer patent document 2 and 4).

Japanese Unexamined Patent Publication No. 2008-300691 Japanese Laid-Open Patent Publication No. 2006-344664 Japanese Unexamined Patent Publication No. 2009-253118 Japanese Unexamined Patent Publication No. 2010-034414

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of forming a solder resist pattern without electric short circuit caused by solder between adjacent connection pads for semiconductor connection and leaving no solder resist residue on the connection pads.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that the said subject could be solved by the following invention as a result of earnestly examining in order to solve the said subject.

(1) (A1) process of forming a soldering resist layer on the surface of a circuit board which has a connection pad,

(B1) Process of thinning until the thickness of a soldering resist layer becomes below the thickness of a connection pad by aqueous alkali solution

The method of forming a soldering resist pattern comprising the above in this order.

(2) (A2) process of forming a soldering resist layer on the surface of the circuit board which has a connection pad and conductor wiring,

(C) exposing portions other than the region to be thinned until the thickness of the solder resist layer becomes equal to or less than the thickness of the connection pad,

(B2) Process of thinning a soldering resist layer until the thickness of the soldering resist layer of a non-exposure part becomes below the thickness of a connection pad by aqueous alkali solution.

Forming method of a solder resist pattern comprising a.

(3) between (A2) and (C)

(D) Process of thinning solder resist layer whole surface by aqueous alkali solution

The formation method of the soldering resist pattern of description to (2) containing a.

(4) (A3) Process of forming a soldering resist layer on the surface of a circuit board which has a connection pad and conductor wiring lower than a connection pad,

(B3) Process of thinning until the thickness of a soldering resist layer is below the thickness of a connection pad, and becomes thicker than the thickness of a conductor wiring by aqueous alkali solution.

(5) The formation method of the soldering resist pattern in any one of (1)-(4) whose aqueous alkali solution is an aqueous solution containing an inorganic alkaline compound, and whose content of the inorganic alkaline compound is 3-25 mass%.

(6) The formation method of the soldering resist pattern as described in (5) whose inorganic alkaline compound is at least 1 sort (s) chosen from alkali metal carbonate, alkali metal phosphate, alkali metal hydroxide, and alkali metal silicate.

(7) The formation method of the soldering resist pattern as described in (5) whose inorganic alkaline compound is an alkali metal silicate.

(8) The formation method of the soldering resist pattern as described in (7) whose alkali metal silicate is sodium metasilicate.

(9) The formation method of the soldering resist pattern as described in (5) whose inorganic alkaline compound is an alkali metal phosphate.

(10) The formation method of the soldering resist pattern as described in (9) whose alkali metal phosphate is at least 1 sort (s) chosen from trisodium phosphate and tripotassium phosphate.

(11) The formation method of the soldering resist pattern as described in (5) whose inorganic alkaline compound is potassium carbonate.

(12) The formation method of the soldering resist pattern in any one of (1)-(4) which is aqueous solution which aqueous alkali solution contains an organic alkaline compound.

(13) The formation method of the soldering resist pattern as described in (12) whose content of an organic alkaline compound is 5-25 mass%.

(14) The formation method of the soldering resist pattern in any one of (1)-(13) whose pH of aqueous alkali solution is 12.5 or more.

(15) After the process of thinning the solder resist layer with an aqueous alkali solution,

(E) Process which contains alkaline compound, and content of this alkaline compound is less than aqueous alkali solution, and processes by aqueous solution of pH 5.0-10.0, temperature 22-50 degreeC

The formation method of the soldering resist pattern in any one of (1)-(14) containing these.

(16) The method of forming the soldering resist pattern in any one of (1)-(15) by the immersion process of the process of thinning a soldering resist layer with aqueous alkali solution.

By any of the formation methods (1)-(4) of the soldering resist pattern in this invention, there is no electrical short circuit by the solder between the connection pads for semiconductor connection which adjoins mutually, and a soldering resist is formed on a connection pad. The effect of leaving no residue can be achieved.

1 is a schematic cross-sectional structural view of a solder resist pattern.
2 is a schematic cross-sectional structural view of a solder resist pattern.
3 is a schematic cross-sectional structural view of a solder resist pattern.
4 is a schematic cross-sectional structural view of a solder resist pattern.
5 is a schematic cross-sectional structural view of a solder resist pattern.
Fig. 6 is a cross sectional view showing an example of a method (1) of forming a solder resist pattern of the present invention.
Fig. 7 is a cross sectional process chart showing an example of a method (2) for forming a soldering resist pattern of the present invention.
FIG. 8 is a cross-sectional process diagram showing an example of a method (3) for forming a solder resist pattern of the present invention. FIG.
Fig. 9 is a cross-sectional process diagram showing an example of the method (4) for forming a soldering resist pattern of the present invention.
10 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method (1) for forming a soldering resist pattern of the present invention.
11 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method (2) for forming a soldering resist pattern of the present invention.
Fig. 12 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method (3) for forming a soldering resist pattern of the present invention.
Fig. 13 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method (4) for forming a soldering resist pattern of the present invention.
14 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method (4) for forming a soldering resist pattern of the present invention.
15 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the prior art.
Fig. 16 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the prior art.

Hereinafter, the formation method of the soldering resist pattern of this invention is demonstrated in detail.

6 is a cross-sectional process diagram showing an example of the method (1) for forming a solder resist pattern of the present invention. The circuit board on which the connection pad 6 was formed on the insulating board 1 is prepared. The subtractive method, the semiadditive method, the additive method, etc. may be used for formation of the connection pad 6. In the step (A1), the solder resist layer 3 is formed to cover the entire substrate surface. In the step (B1), the solder resist layer 3 is thinned with an aqueous alkali solution. FIG. 10 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method for forming a soldering resist pattern of the present invention, wherein the connection pad 6 is exposed from the solder resist layer 3. The resist pattern of the shape is formed. In addition, the thickness of the soldering resist layer 3 in this invention is the value which measured the thickness to the soldering resist layer surface from the surface of the insulating substrate 1 as a starting point.

7 is a cross-sectional process diagram showing an example of the method (2) for forming a soldering resist pattern of the present invention. The circuit board on which the connection pad 6 and the conductor wiring 2 were formed on the insulating board 1 is prepared. In the step (A2), the solder resist layer 3 is formed to cover the entire substrate surface. In the step (C), the active light 5 exposes portions other than the region to be thinned until the thickness of the solder resist layer is equal to or less than the thickness of the connection pad. Although it exposes through the photomask 4 in FIG. 7, you may carry out by a direct drawing system. In process (B2), the soldering resist layer 3 of a non-exposed part is thinned with aqueous alkali solution. Fig. 11 is a three-dimensional explanatory diagram showing an outline of the vicinity of a connection pad of a circuit board produced by the method for forming a soldering resist pattern of the present invention, wherein the connection pad 6 is exposed from the solder resist layer 3. The shape solder resist pattern is formed.

8 is a cross-sectional process diagram showing an example of the method (3) for forming a solder resist pattern of the present invention. The circuit board on which the connection pad 6 and the conductor wiring 2 were formed on the insulating board 1 is prepared. In the step (A2), the solder resist layer 3 is formed to cover the entire substrate surface. In the step (D), the solder resist layer 3 is thinned to a desired thickness within a range thicker than the thickness of the connection pad 6 with an aqueous alkali solution. Since the solder resist layer 3 is exposed to a desired thickness after being thinned, light scattering at the time of exposure is reduced and more accurate patterning is possible. In the step (C), the active light 5 exposes portions other than the region to be thinned until the thickness of the solder resist layer is equal to or less than the thickness of the connection pad. In process (B2), the soldering resist layer 3 of a non-exposed part is thinned with aqueous alkali solution. 12 is a three-dimensional explanatory diagram showing an outline of a connection pad vicinity of a circuit board produced by the method (3) for forming a soldering resist of the present invention, wherein the conductor wiring 2 is covered with the soldering resist layer 3, The soldering resist pattern of the shape in which the connection pad 6 was exposed from the soldering resist layer 3 is formed.

9 is a cross-sectional process diagram showing an example of the method (4) for forming a soldering resist pattern of the present invention. First, the circuit board in which the connection pad 6 and the conductor wiring 2 with a height lower than the connection pad 6 were formed on the insulating board 1 is prepared. In the step (A3), the solder resist layer 3 is formed to cover the entire substrate surface. In the step (B3), the solder resist layer 3 is thinned to a point where the thickness of the solder resist layer 3 is equal to or less than the thickness of the connection pad 6 by the alkali aqueous solution and becomes thicker than the thickness of the conductor wiring 2. . 13 and 14 are three-dimensional explanatory diagrams showing an outline of the vicinity of a connection pad of a circuit board produced by the method of forming a soldering resist pattern (4) of the present invention. 2) is covered with the solder resist layer 3, and the solder resist pattern of the shape which the connection pad 6 exposed from the solder resist layer 3 is formed.

The circuit board which has a connection pad in this invention is a circuit board in which the connection pad for connecting electronic components, such as a semiconductor chip which consists of metals, such as copper, on the insulating board was provided. The circuit board which has a connection pad and conductor wiring on the board | substrate in this invention is a circuit board with connection pad and conductor wiring for connecting electronic components, such as a semiconductor chip which consists of metals, such as copper, on an insulating substrate. As a method of manufacturing the board | substrate with which the connection pad and conductor wiring were formed on the board | substrate, the subtractive method, the semiadditive method, and the additive method are mentioned, for example. In the subtractive method, for example, a through hole called a through hole is drilled through a copper-clad laminate coated with copper foil on a glass base epoxy resin, and plating copper is applied to the surface including the through hole inner wall by electrolytic copper plating. Precipitate. Subsequently, an etching resist layer is formed in a circuit part, and the copper of a non-circuit part is removed by an etching process. Thereafter, the etching resist layer of the circuit portion is removed to produce a circuit board. Moreover, in a semiadditive process, a through hole is made to penetrate the copper clad laminated board which coated very thin copper foil with the glass base epoxy resin, for example, and forms an electroless copper plating layer in the surface containing a through-hole inner wall. Next, a plating resist layer is formed in a non-circuit part, and an electrolytic copper plating layer is formed on the surface of the part which an electroless copper plating layer is exposed by an electrolytic copper plating process. Thereafter, the plating resist layer of the non-circuit portion is removed, and the electroless copper plating layer under the plating resist layer is flash etched away to prepare a circuit board.

In this invention, the circuit board which has a connection pad and conductor wiring lower than a connection pad on a board | substrate is connected with the connection pad for connecting electronic components, such as a semiconductor chip which consists of metals, such as copper, on an insulating board | substrate. It is a circuit board in which conductor wiring lower in height than the pad is formed. As a method of manufacturing the board | substrate which has a connection pad and conductor wiring lower than a connection pad on a board | substrate, the semiadditive method and the additive method are mentioned, for example. In the semiadditive process, a through hole called a through hole is drilled in the copper clad laminated board which coated copper foil with glass base epoxy resin, for example, and an electroless copper plating layer is formed in the surface containing an inner wall of a through hole. Next, a plating resist layer is formed in a non-circuit portion, and an electrolytic copper plating layer (connection pad precursor and conductor wiring) is formed on the surface of the portion where the electroless copper plating layer is exposed by the electrolytic copper plating treatment. Then, a plating resist layer is formed again so that a connection pad precursor part may be exposed, and an electrolytic copper plating layer is formed in the surface of the connection pad precursor part exposed by the electrolytic copper plating process. Thereafter, the plating resist layer is removed, and the circuit board is manufactured by flash etching removing the electroless copper plating layer under the plating resist layer.

The circuit board may be either a single-sided board, a double-sided board, or a multilayer board, and the solder resist pattern forming method of the present invention can be applied to any circuit board as long as it is necessary to form a solder resist pattern.

As the soldering resist which concerns on this invention, any thing can be used as long as it can melt | dissolve or swell the surface of a soldering resist layer by alkaline aqueous solution, and can remove a soldering resist layer. Moreover, one liquid, two liquid, any liquid resist may be sufficient, and a dry film-like resist may be sufficient. A soldering resist contains alkali-soluble resin, a polyfunctional acrylic monomer, a photoinitiator, an epoxy resin, an inorganic filler, etc., for example. As alkali-soluble resin, alkali-soluble resin which has both a photocurability and a thermosetting characteristic is mentioned, For example, acid anhydride to the secondary hydroxyl group of resin which added acrylic acid to the novolak-type epoxy resin and epoxy acrylate-ized. The resin which added this can be mentioned. As a polyfunctional acryl monomer, a trimethylol propane triacrylate, dipentaerythritol hexaacrylate, pentaerythritol triacrylate, etc. are mentioned, for example. Examples of the photopolymerization initiator include 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one. Epoxy resins are used as curing agents. By reacting with the carboxylic acid of the alkali-soluble resin, it can be crosslinked to improve the heat resistance and chemical resistance characteristics. The carboxylic acid and epoxy have poor storage stability because the reaction proceeds at room temperature, and the alkali developing solder resist is generally used before use. The two-liquid form to mix is often taken. Examples of the inorganic fillers include talc, silica, barium sulfate, titanium oxide, and zinc oxide.

In a process (A1), a soldering resist layer is formed in the surface of the circuit board which has a connection pad. In a process (A2), a soldering resist layer is formed in the surface of the circuit board which has a connection pad and conductor wiring. In a process (A3), a soldering resist layer is formed in the surface of the circuit board which has a connection pad and conductor wiring lower than a connection pad. In the formation of the solder resist layer, for example, a liquid resist, screen printing, roll coating, spraying, dipping, curtain coating, bar coating, air knife, hot melt, gravure coating, or brushing Offset printing can be used. Moreover, as long as it is a dry film form, the lamination method and the vacuum lamination method are used.

In a process (C), actinic light is selectively irradiated and hardened | cured to the soldering resist layer of parts other than the area | region thinned. As the exposure method, the xenon lamp, the high pressure mercury lamp, the low pressure mercury lamp, the ultrahigh pressure mercury lamp, the reflection image exposure method using the UV fluorescent lamp as a light source, single sided or double-sided close exposure method using a photomask, proximity method, projection method, or laser scanning exposure method Etc. can be mentioned. The "thinning area" is, for example, an area around the connection pad including on the connection pad or between the connection pads. "Area other than the area | region thinned" is an area | region around conductor wiring containing on conductor wiring or between conductor wirings, for example.

In process (B1), (B2), and (B3), thinning process of a soldering resist layer is performed until it becomes below the thickness of a connection pad by alkali aqueous solution. In the step (D), a thinning process of the solder resist layer is performed in an alkali solution in a range thicker than the thickness of the connection pad 6. Specifically, the surface of the solder resist layer is dissolved or swelled with an aqueous alkali solution to remove the surface of the solder resist layer of the non-exposed portion. In the case of a dry film form, and when a support layer film is formed on a soldering resist layer, a thinning process is performed after peeling off a support layer film.

In the formation method of the soldering resist pattern of this invention, the thickness of the soldering resist layer around a connection pad is determined according to the thickness after formation of a soldering resist layer, and the quantity of the soldering resist layer of an unexposed part thinned. Moreover, in the formation method of the soldering resist pattern of this invention, thin film formation amount can be suitably adjusted in 0.01-500 micrometers. The height from the solder resist layer surface after the thinning to the connection pad surface is appropriately adjusted according to the amount of solder required later.

In the steps (B1), (B2) and (B3), the thinning process is performed until the thickness of the solder resist layer after the thinning process is equal to or thinner than that of the connection pad, but the thickness of the solder resist layer after the thinning is When too thin, electrical insulation between connection pads may become inadequate, the short circuit of electroless nickel / gold plating may generate | occur | produce, or the short circuit by solder may generate | occur | produce between connection pads. Therefore, it is preferable that it is 2 1/2 or more of the thickness of a connection pad, and, as for the thickness of the soldering resist layer after thinning, it is more preferable that it is 3/2 or more.

In the thin film formation process by aqueous alkali solution, you may perform the water washing process as a pretreatment. By pretreatment water washing, hydrophilic groups such as carboxyl groups in the solder resist layer are redirected, and the hydrophilicity of the layer surface is made uniform. Furthermore, contaminants or foreign substances present on the solder resist layer can be removed. Industrial water, tap water, ion-exchanged water, distilled water, etc. are mentioned as water used for pretreatment water washing. Pretreatment washing methods include immersion treatment, paddle treatment, spray treatment, brushing, scraping, and the like. Spray treatment is preferred in view of the removal of contaminants and foreign substances on the solder resist layer. Although spray conditions (temperature, spray pressure, time) can be adjusted suitably, specifically, temperature is preferable 15-30 degreeC, More preferably, it is 20-25 degreeC. Moreover, as for spray pressure, 0.02-0.5 Mpa is preferable, More preferably, it is 0.05-0.3 Mpa.

Moreover, you may contain surfactant in pretreatment wash water. By using surfactant, the surface of a soldering resist layer can be made to hydrophilize more quickly and stably. As surfactant, Anionic surfactant, such as an alkyl sulfate ester salt, a polyoxyethylene alkyl ether sulfate ester salt, an alkylbenzene sulfonate, a fatty acid salt; Polyoxyethylene alkyl ether, polyoxyalkylene derivative, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene hydrogenated castor oil, poly Nonionic interfaces such as oxyethylene alkylamine, alkyl alkanolamide, polyoxyethylene alkylphenyl ether, polyoxyethylene-polyoxypropylene block copolymer (so-called pluronic surfactant), fatty acid pentaerythritol ester, and acetylene glycol Active agent; Cationic surfactants such as alkylamine salts and quaternary ammonium salts; Amphoteric surfactants, such as alkylbetaines, can be used. The pre-washing water treatment is not a problem even if any kind of surfactant is used as long as it does not impair the quality of the solder resist layer, but the anionic, cationic and amphoteric surfactants may be specifically adsorbed on the surface of the resist. Therefore, since the surface of a resist may be partially impaired, it is preferable to use nonionic surfactant. Specific examples of nonionic surfactants include acetylene glycol, such as Nissin Chemical Co., Ltd., Sufinol (registered trademark) 465, Supinol (registered trademark) 485, Supinol (registered trademark) 82, and the like. Can be used.

The amount of surfactant added to the pretreatment wash water varies depending on the characteristics of the various surfactants. In addition to the hydrophilization of the surface of the solder resist layer, the less foaming during the pretreatment wash, and the contaminants adhered on the solder resist layer by the surfactant. In consideration of the removal efficiency of foreign matters, the range of 0.001-0.1 mass% is preferable, the range of 0.001-0.05 mass% is more preferable, and the range of 0.01-0.05 mass% is still more preferable.

The aqueous alkali solution according to the present invention includes aqueous solutions of inorganic alkaline compounds such as alkali metal silicates, alkali metal hydroxides, alkali metal phosphates, alkali metal carbonates, ammonium phosphates and ammonium carbonates; But are not limited to, monoethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, -2-hydroxyethyl ammonium hydroxide (choline), and the like can be given as an aqueous solution of an organic alkaline compound. Examples of the alkali metal include lithium, sodium, potassium, and the like. The said inorganic alkaline compound and organic alkaline compound may be used independently, or may be used in combination of multiple. You may use combining an inorganic alkaline compound and an organic alkaline compound.

When using sodium salt as an alkali metal of an inorganic alkaline compound, it is preferable to mix potassium salt. For example, when sodium carbonate or sodium metasilicate is used, carbonate ions and silicate ions in the component may form insoluble salts with calcium and magnesium contained in water, and may be aggregated in an aqueous alkali solution. Potassium is more soluble in water than sodium and has a higher reactivity with another compound. Thus, carbonate or silicate ions react with potassium preferentially than with calcium or magnesium, preventing insoluble salt formation. I think.

Moreover, in order to make thinner the surface of a soldering resist layer more uniformly, you may add sulfate and sulfite to an aqueous alkali solution. Examples of the sulfates or sulfites include alkali metal sulfates such as lithium, sodium or potassium or alkaline earth metal sulfates or sulfites such as sulfites, magnesium and calcium.

When the aqueous alkali solution is an aqueous solution containing an inorganic alkaline compound, the inorganic alkaline compound is preferably at least any one selected from alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides and alkali metal silicates. Moreover, as for content of an inorganic alkaline compound, 3-25 mass% is preferable. Alkali aqueous solution whose content of an inorganic alkaline compound is less than 3 mass% is a liquid used for image development after exposure by the conventional photolithography system, and is effective when removing the unexposed solder resist layer completely, Thickness nonuniformity may arise easily in the process of thinning in planar thickness without removing completely. Moreover, when it exceeds 25 mass%, precipitation of an inorganic alkaline compound will arise easily and the time-lapse stability of work liquid and workability may be inferior. 5-20 mass% is more preferable, and, as for content of an inorganic alkaline compound, 7-15 mass% is more preferable. Moreover, surfactant, an antifoamer, a solvent, etc. can also be added suitably.

In the thinning process of a soldering resist layer, presence of the inorganic filler insoluble in the aqueous alkali solution contained in a soldering resist layer cannot be ignored. Although the size of the inorganic filler may vary depending on the type, it exists in the content of 30-70 mass% in a layer with some particle size distribution from the submicron order called nanofiller to the tens micron. . The thinning process proceeds by dissolving and diffusing the alkaline compound into the solder resist layer, but the penetration of the alkaline compound is suppressed due to the presence of an insoluble inorganic filler, and the thinning rate may be lowered.

Regarding the inhibition of penetration by such an inorganic filler, the pH of the aqueous alkali solution is preferably 12.5 or more, and more preferably 13.0 or more. The higher the pH of the aqueous alkali solution, the greater the swelling of the solder resist layer when the alkaline compound has penetrated, and the less the effect of the inhibition of penetration by the inorganic filler becomes.

In process (B1), (B2), and (B3), the connection pad surface is exposed by thin film formation process. Usually, when forming a soldering resist layer in the circuit board which has a connection pad and conductor wiring, in consideration of the adhesiveness of a conductor wiring and a soldering resist layer, the surface of a connection pad is roughened by various grinding | polishing processes similarly to conductor wiring. The anchor effect by roughening improves the adhesiveness of a conductor wiring and a soldering resist layer, and maintains high insulation reliability over a long time. Conventionally, when removing a soldering resist layer and exposing a connection pad surface, it is common to use the low concentration aqueous solution of sodium carbonate which is excellent in dispersibility as a developing solution, and the residue of a soldering resist hardly generate | occur | produces on a connection pad surface. However, when the thinning process is performed using a low concentration aqueous solution of sodium carbonate, the surface of the solder resist layer cannot be uniformly treated, resulting in in-plane unevenness.

Therefore, an alkali aqueous solution containing an alkali metal silicate is mentioned as an alkali aqueous solution which does not leave a soldering resist residue on the roughened connection pad surface, while thinning in-plane uniformly. Alkali metal silicate has excellent dissolution diffusion ability of the solder resist layer compared to other inorganic alkaline compounds, and residue residues are less likely to occur on the connection pad surface. General formula of alkali metal silicate is shown to following formula (i). Alkali metal silicate is a generic term for chemicals in which three components are continuously changed at various ratios, and the mass ratio calculated from the molar ratio (mass ratio in case of sodium salt = molar ratio × 1.032, mass ratio in case of potassium salt = molar ratio × 1.568). The name changes accordingly. For example, in the case of a sodium salt, sodium orthosilicate which has a mass ratio of 0.5, sodium metasilicate which has a mass ratio of 1.0, and those whose mass ratio is 1.3-4 are generally called sodium silicate. A mass ratio of 1 or less is called crystalline sodium silicate, while a mass ratio of greater than 1 is amorphous, and the mass ratio can be continuously changed. In addition, the viscosity of a solution of sodium silicate changes remarkably according to mass ratio, concentration, temperature, and the like. That is, the higher the mass ratio, the higher the concentration, or the lower the temperature, the higher the viscosity of the solution. The solution of sodium silicate contains a silicate ion monomer, polysilicate ion, colloidal silicate ion micelle and the like and takes various forms depending on the mass ratio and concentration. In the case where the mass ratio is 1 or less, the silicate ion monomer is mainly present, and in the high mass ratio solution, dimer and polysilicate ion micelles are contained in addition to the silicate ion monomer, and the concentration of the polysilicate ion micelle increases with the increase in the mass ratio. By increase of this polysilicate ion micelle, the mass mean molecular weight of a solution increases and a viscosity rises. In general, if the mass ratio is greater than 2, attention should be paid to the increase in viscosity. In this regard, in the case of sodium salt, sodium metasilicate is most preferably used in terms of stability and workability of the aqueous solution. In addition, since potassium salts have higher solubility in water than sodium salts, aqueous solutions are easily solidified and not separated, and various ones can be used. 5-25 mass% is more preferable, and, as for content of an alkali metal silicate, 7-20 mass% is more preferable.

_{M 2 O · nSiO 2 · xH} 2 O (i)

[M: sodium or potassium, n: molar ratio (SiO ₂ / M ₂ O)]

As an inorganic alkaline compound which has the dissolution diffusion capability of the soldering resist layer similar to alkali metal silicate, the aqueous alkali solution containing alkali metal phosphate is mentioned. As the alkali metal phosphate, alkali strong trisodium phosphate or tripotassium phosphate in which the alkali metal is triatomicly coordinated is preferably used. 5-20 mass% is more preferable, and, as for content of an alkali metal phosphate, 7-15 mass% is more preferable.

Moreover, the aqueous solution containing potassium carbonate as an inorganic alkaline compound can also melt | dissolve and diffuse a soldering resist layer suitably. Although carbonate has a greater hydration power than silicate and phosphate, potassium is an alkali metal, and has a greater tendency of ionization in aqueous solution than sodium, and thus advantageously dissolves and diffuses the solder resist layer. 3-15 mass% is more preferable, and, as for content of potassium carbonate, 5-10 mass% is more preferable.

When the aqueous alkali solution is an aqueous solution containing an inorganic alkaline compound, examples of the organic alkaline compound contained in the alkaline aqueous solution include tetramethylammonium hydroxide (TMAH) and trimethyl-2-hydroxyethylammonium hydroxide (choline). It is preferable to include at least any 1 selected. Moreover, the aqueous alkali solution whose content of an organic alkaline compound is 5-25 mass% can be used preferably. If it is less than 5 mass%, in-plane nonuniformity may arise easily in a thin film formation process. Moreover, when it exceeds 25 mass%, a thin film formation speed may fall. 7-20 mass% is more preferable, and, as for content of an organic alkaline compound, 10-20 mass% is more preferable. Moreover, surfactant, an antifoamer, a solvent, etc. can also be added suitably. In the case of using an alkali aqueous solution containing an alkali metal salt, depending on the composition of the solder resist to be used, alkali metal ions may flow into the solder resist layer to lower the insulation reliability, but an aqueous alkali solution containing an organic alkaline compound may be used. In the case of using, the effect that the insulation reliability decrease is suppressed is obtained.

As for the temperature of aqueous alkali solution, 15-35 degreeC is preferable, More preferably, it is 20-30 degreeC. If the temperature is too low, the penetration rate of the alkaline compound into the solder resist layer may be slowed down, and a long time is required to thin the desired thickness. On the other hand, when the temperature is too high, dissolution diffusion proceeds at the same time as the alkaline compound penetrates into the solder resist layer, which is not preferable because the film thickness unevenness may easily occur in the plane.

In the thinning process of a soldering resist layer, it is preferable to use the neutralization titration method as a liquid management method of aqueous alkali solution. In short, in order to maintain the thin film-forming ability of aqueous alkali solution, it is preferable to perform management by concentration as an index of liquid management. Although management by pH can also be considered as an index of liquid management, alkali-soluble resin having an acid group terminal such as a carboxylic acid group contained in the solder resist layer and a high concentration of aqueous alkali solution are brought into contact with each other, and the pH is measured at the actual concentration. Since it is observed lower than the value which becomes, it is difficult to manage liquid strictly at pH. Moreover, in concentration control by a neutralization titration method, it is preferable to replenish the aqueous alkali solution of the same density | concentration as an initial stage concentration as a supplement liquid. Usually, in the developing process by the low concentration aqueous alkali solution in the soldering resist pattern formation by the photolithographic method, it is common to replenish the process liquid of higher concentration than the initial concentration, but in thinning the soldering resist layer which concerns on this invention, alkali The influence of the change in the concentration of the aqueous solution on the thinning of the solution is so large that more precise concentration management is required. Specifically, in the case of the development treatment with a low concentration aqueous alkali solution in the formation of the solder resist pattern by the photolithography method, the development treatment is performed at a time of about 1.5 to 2.0 times the time when all the solder resist layers are eluted. In thinning of the soldering resist layer which concerns on this invention, it becomes important to make thin film uniformly in surface as much as desired. Therefore, more precise concentration control is necessary. In addition, when replenishing a high concentration of aqueous alkali solution, it is common to perform an operation such as mechanical agitation so that the concentration of the liquid in the bath becomes a target that is instantaneously targeted. In some cases, it is also preferable to replenish an aqueous alkali solution having the same concentration as the initial concentration.

As a method of concentration management by a neutralization titration method, specifically, the predetermined amount of aqueous alkali solution is taken out of the continuous thin film processing apparatus, hydrochloric acid or sulfuric acid is dripped while measuring pH, and the acid added until it reaches a neutralization point. The concentration of the alkaline compound is obtained from the amount of. The concentration of the alkaline compound is calculated from the obtained titration curve. In the acidic region, since the titration curve is shifted under the influence of the acid groups contained in the solder resist layer, the accurate concentration may not be predicted. Therefore, it is necessary to calculate the concentration in the alkaline region. When this concentration is out of the predetermined range of the aqueous alkali solution, the aqueous alkali solution of the same concentration as the initial concentration is added and replenished. The "predetermined range" refers to a concentration range of -5% to + 5% with respect to the initial concentration, also referred to as "target concentration" below. By performing the operation of measuring the alkaline compound concentration by such a neutralization titration and adding and replenishing the alkaline aqueous solution every predetermined time, it becomes possible to maintain the thinning capacity within a certain range.

From neutralization titration to addition replenishment of aqueous alkali solution may be carried out automatically. As an automatic system, for example, a function (eg, a metering pump, a metering tube, etc.), a pH meter, a function of stirring a liquid (magnetic stirrer, etc.), a titration liquid (acidic acid), at least automatically, is measured while measuring an aqueous alkali solution at a predetermined time. Liquid) dropping function (such as a pump for driving a pulse motor), an estimated neutralizing point pH is set, and when the pH is reached, the dropping of the titrant is stopped, the function of calculating the dripping amount of the titrant, and the drop amount A function of calculating the concentration of the alkaline compound, a function of setting the target concentration, and a function of supplying an alkaline aqueous solution having the same concentration as the initial concentration of the amount calculated by [(target concentration-measured concentration) x alkaline aqueous solution tank volume / target concentration]. And a system including a function of washing a titration vessel after completion of a series of titration measurements (such as a fixed pump). The formula for replenishing the liquid is based on the above, but it is preferable to make various corrections while watching the actual process.

In the above example, the estimated neutralization point pH was set, and the concentration of the alkaline compound was calculated from the amount of acid dropped until the pH was reached.However, in order to increase the measurement accuracy, the pH beyond the neutralization point pH as a proper termination pH (neutralization point If the pH is 8, it is set to about 7 to 6), and the acid dropping amount at which the rate of change of pH is greatest is calculated from the start of dropping to the end of dropping, and the neutralization point is obtained from that point. It is preferable to calculate the concentration of the compound.

Although the thin film formation process by aqueous alkali solution can use methods, such as an immersion process, a paddle process, a spray process, brushing, and a scraping, an immersion process is preferable. In processing methods other than the immersion treatment, bubbles are likely to be generated in the aqueous alkali solution, and the generated bubbles may adhere to the surface of the solder resist layer during the thinning treatment, resulting in uneven film thickness. In the case of using a spray treatment or the like, it is preferable to make the spray pressure as small as possible so as not to generate bubbles.

After the steps (B1), (B2), (B3) and (D), it is preferable to sufficiently wash the circuit board with water. The solder resist layer to be removed is completely dissolved by removing the circuit board with water. Dipping treatment, paddle treatment, spray treatment, and the like are the methods of washing with water, and spray treatment is most suitable in terms of dissolution diffusion rate of the solder resist layer and uniformity of liquid supply. Moreover, 25-45 degreeC is more preferable and, as for the temperature of water washing water, 27-40 degreeC is still more preferable.

As in the method for forming the soldering resist pattern of the present invention, after the step (B1), (B2), (B3) or (D) of thinning the soldering resist layer, (E) an alkaline compound is contained, and the content of the alkaline compound is It is less than alkaline aqueous solution, and it is preferable to include the process of processing with aqueous solution of pH 5.0-10.0, temperature 22-50 degreeC. In addition, process (E) is performed before washing | cleaning with water. In the step (E), the aqueous solution containing the alkaline compound has an excellent buffering capacity in the alkaline region, so that a sudden increase in pH can be prevented, which helps to maintain excellent in-plane uniformity. Moreover, by using the aqueous solution of pH 5.0-10.0, dissolution diffusion property of a soldering resist layer can be kept constant and stable continuous thin film formation process is attained. Moreover, the effect that it can process without leaving a soldering resist residue on the roughened connection pad surface is obtained by making the temperature of aqueous solution into 22-50 degreeC.

As an alkaline compound in the aqueous solution of process (E), inorganic alkaline compounds, such as an alkali metal carbonate, an alkali metal phosphate, an alkali metal hydroxide, and an alkali metal silicate, tetramethylammonium hydroxide (TMAH), trimethyl-2- hydride Organic alkaline compounds, such as oxyethylammonium hydroxide (choline), are mentioned. The alkaline compound in the alkaline aqueous solution used in the step (B1), (B2), (B3) or (D) carried out before the step (E) and the alkaline compound used in the step (E) may be the same or different. However, when two processes are normally performed continuously, when it considers that there exists mixing of an alkaline compound at the time of transition from a previous process to a later process, it is common that the same alkaline compound is contained.

Content of the alkaline compound in the aqueous solution of process (E) is less than content in the aqueous alkali solution used at process (B1), (B2), (B3) or (D). That is, the aqueous solution which is thinner than the aqueous alkali solution used at a process (B1), (B2), (B3) or (D) is used at a process (E). If the aqueous solution of the step (E) is darker than the aqueous alkali solution used in the step (B1), (B2), (B3) or (D), a problem arises that control of the amount of thinning of the solder resist layer becomes difficult.

When pH of the aqueous solution of a process (E) is less than 5.0, the soldering resist component melt | dissolved in aqueous solution aggregates, and there exists a possibility that it may become insoluble sludge and adhere to the solder resist layer surface after thinning. On the other hand, when the pH of the aqueous solution of process (E) exceeds 10.0, dissolution diffusion of a soldering resist layer is accelerated | stimulated and film thickness nonuniformity may arise easily in surface. Moreover, pH of aqueous solution can be adjusted using a sulfuric acid, phosphoric acid, hydrochloric acid, etc.

In addition, although pH of aqueous alkali solution and aqueous solution of a process (E) has temperature dependence, pH which concerns on this invention points out the value in 22 degreeC of liquid temperature. Temperature compensation function corresponding to the temperature characteristics of the pH glass electrode (correction of properties change due to the temperature of the pH glass electrode) and temperature conversion function corresponding to the temperature characteristic of the aqueous solution (function to convert the pH value at a constant temperature) By measuring using the pH meter provided with), the pH value of the aqueous solution in 22 degreeC can be investigated.

In process (E), 25-45 degreeC is more preferable and, as for the temperature of aqueous solution, 27-40 degreeC is still more preferable. The temperature of the aqueous solution in the step (E) affects the dissolution diffusion efficiency of the soldering resist layer, and below 22 ° C, poor dissolution of the soldering resist layer components causes solder resist residues to remain on the roughened connection pad surface. It's easy. On the other hand, when it exceeds 50 degreeC, the problem of temperature control in evaporation of aqueous solution, continuous operation, and a restriction | limiting in apparatus design may arise, and it is unpreferable.

In addition, an antifoaming agent effective for defoaming (foaming, blistering) can be added to the aqueous solution of step (E). When the thinning process of a soldering resist layer is performed continuously and a large amount of soldering resist components melt | dissolve in aqueous solution, foaming will become intense and it will be in the state which continuous operation cannot be performed. The antifoaming agent is to suppress such foaming. The antifoaming agent is broadly classified into a silicone antifoaming agent and an organic antifoaming agent.

Silicone antifoaming agents are excellent in the speed effect of the defoaming, but are prone to defects such as agglomeration and craters in terms of persistence, compatibility, and wettability of the defoaming ability. On the other hand, organic antifoaming agents include surfactants, paraffins, mineral oils, and the like, and exhibit excellent durability compared to silicone antifoams in the defoaming of aqueous foaming liquids. As the surfactant-based antifoaming agent, many emulsion-dispersing surfactants having a low HLB using an emulsifier are used. Although this type of antifoaming agent is relatively persistent, many antifoaming agents are smaller than others. Among them, the surfactant represented by the following formula (1) or (2) having a highly stable molecular structure of acetylene group centered on the acetylene group has a small molecular weight and an effect of greatly lowering the surface tension, and not only functions such as antifoaming and dispersibility, Wetting and compatibility also show excellent performance.

[Formula 1]

In Formula 1 and Formula 2, m and n are 0 or an integer greater than or equal to 1, and 0 <= m + n <= 30.

As such surfactant, Nisshin Chemical Co., Ltd. Suminol (trademark) 104, Sufinol (trademark) DF110D, Sufinol (trademark) MD-20, Surfinol (trademark) 420, Surfact Knoll® 440, Sufinol® 465, Sufinol® 485, Orpin® AF-103, Orpin® E1004, and the like. In particular, in terms of anti-foaming, Surfinol® 104 and Orpin (registered trademark) AF-103 are preferred. In water-soluble form, Surfinol (registered trademark) 465, Supinol (registered trademark) 485, and orpin (registered trademark) E1004 and the like are preferred. In addition to these, the use of Surfinol® MD-20 is most preferred in consideration of the compatibility, the persistence of the antifoaming effect, and the dispersibility of the oily scum accompanying the increase of dissolution. .

It is preferable to add 0.01-5.0 g of these surfactants per 1 g of solder resists melt-dispersed, More preferably, they are 0.05-2.0 g. If it is less than 0.01 g, the defoaming effect with respect to foaming may become inadequate. When it exceeds 5.0 g, there is a possibility that layer separation of the surfactant occurs. Moreover, by adding surfactant in the state disperse | distributed to aqueous solution, it diffuses rapidly and exhibits the defoaming effect.

In addition, the paraffin type antifoaming agent is an emulsion dispersion of paraffin wax or its modified substance using an emulsifier, and is preferably used as an antifoaming agent containing mineral oil as a component. Content of mineral oil and other components contained can make antifoaming effect and sustainability compatible. Examples of the mineral oil to be used include mainly paraffinic or naphthenic saturated hydrocarbons obtained from petroleum crude oil or a processed product thereof, for example, liquid paraffin, lubricating oil, gasoline, kerosene, diesel oil, heavy oil, and machine oil. Mineral oil type antifoaming agent contains mineral oil as a major defoaming component, and some may mix metal soap, silicon dioxide, etc. in order to enhance the defoaming effect. Defoamers containing mineral oil as a major defoaming component have very poor dispersibility in water, and the oil separated on the water surface is suspended, or the separated oil adheres to the surface of the solder resist layer and further contaminates the bathtub. There is.

It is preferable that the defoaming agent containing mineral oil is 20 mass% or less in content of mineral oil. Mineral oils are generally considered to have a large suppression effect but no sustainability. The mineral oil is contained in an amount of 20% by mass or less and supplemented with other components to achieve sustaining effects. 10-20 mass% is more preferable, and, as for content of the mineral oil contained in an antifoamer, 15-20 mass% is further more preferable. As the antifoaming agent having a content of mineral oil of 20% by mass or less, a commercially available one can be used. Specific examples thereof include Chloris (registered trademark) 505, 514, 521, etc. manufactured by Kurita Industries, Ltd. Although the addition amount of an antifoamer does not have a restriction | limiting in particular, 1-10000 ppm is preferable as a concentration, and 10-1000 ppm is more preferable.

In the thinning process of the soldering resist layer which concerns on this invention, it is preferable that melt | dissolution concentration in the aqueous solution of the process (E) of the soldering resist component removed by thinning is 0.5 mass% or less, More preferably, it is 0.3 mass% or less More preferably, it is 0.2 mass% or less. When the amount of melt | dissolution of the soldering resist component in the aqueous solution of a process (E) increases by a continuous thinning process, haze nonuniformity may generate | occur | produce on the surface of the soldering resist which thinned and the film thickness nonuniformity may arise in the part. The haze nonuniformity is considered to be caused by poor dispersibility of the solder resist layer in the thinning process, resulting in dissolution, and precipitation of insoluble components. In addition, the soldering resist component melt | dissolved in the process (E) aqueous solution can be removed at any time by circulating a filter. Although the kind of filter can be used without a restriction | limiting, for example, the depth cartridge filter, a wind cartridge filter, etc. made by Advantech Toyo Co., Ltd. can be used. The number of filters to be used, the hole diameter, and the like can be freely selected as necessary.

As a measuring method of the melt concentration in the aqueous solution of the process (E) of a soldering resist component, it can measure as a difference from a dry mass. Specifically, for example, 10 g of an aqueous solution in which a solder resist component is dissolved is taken into a chalet, and put into a dryer having a temperature of 100 ° C. to completely evaporate water. Next, by measuring the mass after evaporation, the quantity (mass%) of the soldering resist component melt | dissolved in 10 g of solution can be calculated.

As a liquid supply method in a process (E), spraying is most preferable from the melt diffusion speed of a soldering resist layer, and the uniformity of liquid supply. Moreover, it is preferable to set it as 0.01-0.5 Mpa, More preferably, it is 0.02-0.3 Mpa. In addition, it is preferable to spray in the direction which inclines with respect to the direction perpendicular | vertical to a soldering resist layer surface, in order to make a liquid flow efficiently on the soldering resist layer surface.

Time from the end of step (B1), (B2), (B3) or (D) to the start of washing with water and from the end of step (B1), (B2), (B3) or (D) 6 seconds or less are preferable, and, as for time to start of (), 4 seconds or less are more preferable. The amount of thinning of the soldering resist layer is determined according to the total time from the start of the step (B1), (B2), (B3) or (D) to washing with water or just before the start of the step (E). In short, the time from the end of the steps (B1), (B2), (B3) or (D) to the washing with water or the start of the step (E) also affects the amount of thinning. Here, when carrying out thinning process using a thinning process apparatus, making transfer time to 0 from a process (B1), (B2), (B3) or (D) to zero considers a conveyance speed. Also practically impossible. When the time from the end of the step (B1), (B2), (B3) or (D) to the start of the step (E) becomes long, the degree of swelling of the aqueous alkali solution into the solder resist layer and the progress of penetration become uneven and the in-plane Film thickness unevenness may occur.

Example

Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to this Example.

(Example 1)

The circuit board which has the connection pad of 50 micrometers of wiring width, and 50 micrometers of wiring width space | interval was produced using the subtractive method for the copper clad laminated board (area 170 mm x 200 mm, copper foil thickness 18 micrometers, substrate thickness 0.4 mm). Subsequently, a 30-micrometer-thick solder resist film (manufactured by Taiyo Ink Co., Ltd., product name: PFR-800 AUS410) was vacuum thermocompressed on the circuit board by using a vacuum laminator (laminate temperature 75 ° C, suction time 30). Seconds, pressurization time 10 seconds). Thereby, the soldering resist layer with a film thickness of 38 micrometers from the insulating substrate surface to the soldering resist layer surface was formed.

Using the alkali aqueous solution of Table 1 (liquid temperature of 25 degreeC), thin film formation process is performed by the immersion system for the time of Table 1 so that the thickness of the soldering resist layer from an insulating substrate surface may be 12 micrometers on average, and sufficient water washing is performed. Through the treatment (liquid temperature 25 ° C.) and cold air drying, a thin solder resist layer was obtained. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small that good in-plane uniformity was obtained.

Next, in order to harden a soldering resist layer, the whole surface exposure was carried out by exposure amount 500mJ / cm <2>, and the thermosetting process was performed at 150 degreeC for 60 minutes, and the soldering resist pattern was then formed. The formed soldering resist pattern has the structure shown in FIG. 10. As a result of observing this with an optical microscope, the metal surface of the connection pad 6 with a thickness of 18 micrometers was exposed, and 12 micrometers in thickness between the adjacent connection pads 6 is shown. Solder resist layer 3 was embedded.

(Example 2)

The circuit board which has conductor wiring of 50 micrometers of wiring width, and 50 micrometers of wiring width space | interval was produced using the subtractive method for the copper clad laminated board (area 170mmx200mm, copper foil thickness 18micrometer, substrate thickness 0.4mm). Subsequently, a 30-micrometer-thick solder resist film (manufactured by Taiyo Ink Co., Ltd., product name: PFR-800 AUS410) was vacuum thermocompressed on the circuit board by using a vacuum laminator (laminate temperature 75 ° C, suction time 30). Seconds, pressurization time 10 seconds). Thereby, the soldering resist layer with a film thickness of 38 micrometers from the insulating substrate surface to the soldering resist layer surface was formed.

A part of conductor wiring was used as a connection pad, and in order to harden the soldering resist layer of an area | region other than 50 micrometers from the edge part of this connection pad, the close_contact | adherence exposure by the photomask was performed by exposure amount 300mJ / cm <2>.

Using the alkali aqueous solution of Table 1 (liquid temperature of 25 degreeC), thin film formation process is performed by the immersion system in the time of Table 1 so that the thickness of the soldering resist layer from the insulating substrate surface of a non-exposed part may be 12 micrometers on average. , The sufficient water washing process (liquid temperature 25 degreeC), cold air drying, and the thin soldering resist layer was obtained. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small that good in-plane uniformity was obtained.

Next, in order to harden a soldering resist layer, the whole surface was exposed by exposure amount 500mJ / cm <2>, and the thermosetting process was performed at 150 degreeC for 60 minutes. The formed soldering resist pattern is the structure shown in FIG. 11, and when this was observed with the optical microscope, the conductor wiring 2 of thickness 18micrometer was coat | covered with the soldering resist layer 3 of thickness 38micrometer, and the connection of thickness 18micrometer As for the pad 6, the metal surface was exposed, and the soldering resist layer 3 with a thickness of 12 micrometers was embedded between the adjacent connection pads 6.

(Example 3)

Using the alkali aqueous solution (table temperature of 25 degreeC) of Table 1, the thin film formation process is performed by the immersion system until the thickness of the soldering resist layer from the insulating substrate surface becomes an average of 28 micrometers, and sufficient water washing process (liquid temperature 25) ° C) and cold air drying to obtain a thin solder resist layer.

A part of conductor wiring was used as a connection pad, and in order to harden the soldering resist layer of an area | region other than 50 micrometers from the edge part of this connection pad, the close_contact | adherence exposure by the photomask was performed with the exposure amount of 300 mJ / cm <2>.

Using the alkali aqueous solution of Table 1 (liquid temperature of 25 degreeC), thin film formation process is performed by the immersion system in the time of Table 1 so that the thickness of the soldering resist layer from the insulating substrate surface of a non-exposed part may be 12 micrometers on average. The soldering resist layer thinned by sufficient water washing process (liquid temperature 25 degreeC) and cold air drying was obtained. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small that good in-plane uniformity was obtained.

Next, in order to harden a soldering resist layer, the whole surface was exposed by exposure amount 500mJ / cm <2>, and the thermosetting process was performed at 150 degreeC for 60 minutes. The formed solder resist pattern has the structure shown in FIG. 12, and as a result of observing this with an optical microscope, the conductor wiring 2 of thickness 18micrometer was coat | covered with the soldering resist layer 3 of thickness 28micrometer, and the connection of thickness 18micrometer As for the pad 6, the metal surface was exposed, and the soldering resist layer 3 with a thickness of 12 micrometers was embedded between the adjacent connection pads 6.

(Example 4)

Using a semi-additive method for a copper clad laminate (area 170 mm × 200 mm, substrate thickness 0.4 mm), a connection pad having a thickness of 25 μm, a wiring width of 50 μm, a wiring width of 50 μm, a thickness of 15 μm, and a wiring width of 50 μm The circuit board which has conductor wiring of 50 micrometers of wiring width intervals was produced. Subsequently, a 30-micrometer-thick solder resist film (manufactured by Taiyo Ink Co., Ltd., product name: PFR-800 AUS410) was vacuum thermocompressed on the circuit board by using a vacuum laminator (laminate temperature 75 ° C, suction time 30). Seconds, pressurization time 10 seconds). Thereby, the soldering resist layer with a film thickness of 38 micrometers from the insulating substrate surface to the soldering resist layer surface was formed.

Using the alkali aqueous solution of Table 1 (liquid temperature of 25 degreeC), thin film treatment is performed by the immersion method for the time of Table 1 so that the thickness of the soldering resist layer from an insulating substrate surface may be 20 micrometers on average, and sufficient water washing is performed. Through the treatment (liquid temperature 25 ° C.) and cold air drying, a thin solder resist layer was obtained. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 1. The difference between the film thickness maximum value and the film thickness minimum value was sufficiently small that good in-plane uniformity was obtained.

Next, in order to harden a soldering resist layer, the whole surface was exposed by exposure amount 500mJ / cm <2>, and the thermosetting process was performed at 150 degreeC for 60 minutes. The formed solder resist pattern has the structure shown in Fig. 13, and the conductor wiring 2 having a thickness of 15 mu m is completely covered with the solder resist layer 3 having a thickness of 20 mu m, and the connection pad 6 having a thickness of 25 mu m has its metal surface. This was exposed and the soldering resist layer 3 with a thickness of 20 micrometers was embedded between the adjacent connection pads 6.

(Example 5)

The copper-clad laminate (area 170 mm × 200 mm, substrate thickness 0.4 mm) using the semi-additive method, has a wiring width of 50 µm and a wiring width interval of 50 µm, and each connection has a connection pad having a thickness of 25 µm and a thickness of 15 µm. The circuit board with which conductor wiring was formed in staircase was produced. Subsequently, a 30-micrometer-thick solder resist film (manufactured by Taiyo Ink Co., Ltd., product name: PFR-800 AUS410) was vacuum thermocompressed on the circuit board by using a vacuum laminator (laminate temperature 75 ° C, suction time 30). Seconds, pressurization time 10 seconds). Thereby, the soldering resist layer with a film thickness of 38 micrometers from the insulating substrate surface to the soldering resist layer surface was formed.

Subsequently, in order to harden a soldering resist layer, the whole surface was exposed by exposure amount 500mJ / cm <2>, and the thermosetting process was performed at 150 degreeC for 60 minutes continuously. The formed solder resist pattern has the structure shown in FIG. 14, and the conductor wiring 2 having a thickness of 15 μm is completely covered with the solder resist layer 3 having a thickness of 20 μm, and the connection pad 6 having a thickness of 25 μm has its metal surface. This was exposed and the soldering resist layer 3 with a thickness of 20 micrometers was embedded between the adjacent connection pads 6.

(Comparative Example 1)

In order to harden the soldering resist layer of regions other than 50 micrometers from the edge part of this connection pad using a part of conductor wiring as the connection pad, the close_contact | adherence exposure by the photomask was performed with the exposure amount of 300 mJ / cm <2>.

Subsequently, using the 1 mass% aqueous sodium carbonate solution (30 degreeC of liquid temperature), all the soldering resist layers of a non-exposed part were removed by image development, and the thermosetting process was performed at 150 degreeC for 60 minutes. The formed solder resist pattern had the structure shown in FIG. 15, and the conductor wiring 2 of thickness 18micrometer was coat | covered with the soldering resist layer 3 of thickness 38micrometer. In the structure shown in FIG. 15, since there is no soldering resist layer 3 between adjacent connection pads 6, the connection defect by the solder bridge generate | occur | produced in the mounting process.

(Comparative Example 2)

Exposure amount 300 mJ / in order to harden the soldering resist layer of the area | region except the 50 micrometers from the edge part of this connection pad, and the area | region of 20 micrometers width from the intermediate point between adjacent connection pads using a part of conductor wiring as a connection pad. Tight exposure by the photomask was performed in cm <2>.

Subsequently, using the 1 mass% aqueous sodium carbonate solution (30 degreeC of liquid temperature), all the soldering resist layers of a non-exposed part were removed by image development, and the thermosetting process was performed at 150 degreeC for 60 minutes. The formed solder resist pattern has the structure shown in FIG. 16, and the conductor wiring 2 of thickness 18 micrometers is coat | covered with the solder resist layer 3 of thickness 38 micrometers, and the width | variety from the intermediate point between adjacent connection pads 6 is shown. The soldering resist layer 3 of thickness 38micrometer existed in the part of 20micrometer. However, depending on the observation point, the solder resist layer 3 on the insulating substrate 1 came into contact with the connection pad 6 due to the positional shift in the exposure step. In such a state, the amount of solder for ensuring the electrical connection between the electrode terminal and the connection pad cannot be secured, and the solder resist layer 3 which is out of position due to the connection failure at the time of joining interferes with the component mounting. .

(Comparative Example 3)

It exposed at 1000 mJ / cm <2> of exposure amounts to the soldering resist whole surface, and the thermosetting process was performed at 150 degreeC for 60 minutes after that. The pattern for wet blasting was formed in the soldering resist layer surface after thermosetting, and the wet blasting process was performed until the connection pad surface was exposed as a mask. Thereafter, the mask pattern was removed. The formed soldering resist pattern is the structure shown in FIG. 11, and when this was observed with the optical microscope, the conductor wiring 2 of thickness 18micrometer was coat | covered with the soldering resist layer 3 of thickness 38micrometer, and the connection of thickness 18micrometer As for the pad 6, the metal surface was exposed, and the soldering resist layer 3 was embedded between the adjacent connection pads 6. However, there was a variation in the thickness of the solder resist layer embedded between the adjacent connection pads 6, and there was a portion in which the metal surface of the connection pad 6 was not completely exposed and the solder resist layer remained. Moreover, many scratches by the blasting process were confirmed by the connection pad 6 in which the surface was exposed.

(Examples 6 to 27)

Using the alkali aqueous solution of Table 1, the soldering resist pattern was formed by the method similar to Example 2. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 1. In Example 2, 6-27, when using the aqueous solution whose content of an inorganic alkaline compound is 3-25 mass% (Examples 2, 7-27), the difference of a film thickness maximum value and a film thickness minimum value is small enough thinly A solder resist pattern with very good in-plane uniformity was formed. In Example 6 whose content of an inorganic alkaline compound is 1 mass%, the tendency for the in-plane uniformity after thinning to deteriorate was large because the difference of the film thickness maximum value and film thickness minimum value was slightly large. As for the thinning rate, in the case of the concentration of 7% by mass in the comparison of Examples 2 and 6 to 12, the thinning rate is the maximum in the case of the concentration of 20% by mass in the comparison of Examples 13 to 18, and at higher concentrations, There was a tendency to deteriorate. In addition, the time required for the thinning treatment differs depending on the type of the inorganic alkaline compound, and particularly when sodium metasilicate is used, a very fast thinning rate is obtained.

(Examples 28 to 41)

After manufacturing the circuit board which has conductor wiring to the copper clad laminated board using the subtractive method, it roughens a conductor circuit surface by chemical polishing process, except having used the aqueous alkali solution of Table 2 as aqueous alkali solution, respectively. A soldering resist pattern was formed in the same manner as in Example 2. In order to examine the presence or absence of the solder resist residue in the roughening surface of the connection pad exposed by the thin film formation process, the electroless nickel plating process was performed with respect to the exposed copper surface. Moreover, plating pretreatment was performed as needed, and when there existed a residue, the removal property was also investigated. The evaluation criteria are as follows. The results are shown in Table 2. In particular, in the case of using an aqueous alkali solution containing sodium metasilicate, no residue of the solder resist component was found even on the roughened surface.

○: no residue of solder resist components

(Triangle | delta): The level which is easy to remove by plating pretreatment although there exists a trace amount residue

X: The level which has a large amount of residue and is not easy to remove by plating pretreatment.

(Examples 42 to 55)

A soldering resist pattern was formed in the same manner as in Example 2 except that the aqueous alkali solution shown in Table 3 was used. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 3. When the aqueous solution of 5-25 mass% content of an organic alkaline compound was used, the difference of the film thickness maximum value and the film thickness minimum value was small enough, and the soldering resist pattern with very good in-plane uniformity after thin film formation was formed. In Example 42 and Example 43 whose content of an organic alkaline compound is 3 mass% or less, the difference in film thickness maximum value and film thickness minimum value was slightly large, and the tendency for in-plane uniformity after thin film formation to deteriorate was confirmed.

(Examples 56-63)

After manufacturing the circuit board which has conductor wiring to a copper clad laminated board using the subtractive method, it roughens a conductor circuit surface by chemical polishing process, except having used the aqueous alkali solution of Table 4 as aqueous alkali solution, respectively. A soldering resist pattern was formed in the same manner as in Example 2. In order to examine the presence or absence of the solder resist residue in the roughening surface of the connection pad exposed by the thin film formation process, the electroless nickel plating process was performed with respect to the exposed copper surface. Moreover, plating pretreatment was performed as needed, and when there existed a residue, the removal property was also investigated. The evaluation criteria are as follows. The results are shown in Table 4. Even when an organic alkaline compound was used, the residue of the soldering resist component on the roughening surface was a level which can be easily removed by plating pretreatment, and there was no problem in practical use.

After ion-extracting the soldering resist patterns produced in Example 1, Example 2, Example 19, Example 47, Example 53, and Comparative Example 1 with 100 degreeC of hot water, respectively, it extracted with sodium by the ion chromatography method from the extract liquid. Ion concentration was measured. The results are shown in Table 5. In the case of using an aqueous alkali solution containing an organic alkaline compound, there was little mixing of sodium ions into the solder resist layer. On the other hand, when the alkaline aqueous solution containing an inorganic alkaline compound was used, mixing of sodium ion in the soldering resist layer of the grade equivalent to the developing process in the comparative example 1 was observed. However, in Example 1, when the entire soldering resist layer was thinned using an inorganic alkaline compound, the amount of sodium ions mixed was small. From this point of view, it was found that the incorporation of sodium ions tends to increase mainly when the exposed portion of the solder resist layer is present.

(Examples 64 to 91)

In the thinning process of a soldering resist layer, spray treatment (spray pressure 0.20 MPa) is used using the aqueous alkali solution of Table 6 (liquid temperature 25 degreeC), and also using the aqueous solution of process (E) shown in Table 7 before a water washing process. A soldering resist pattern was formed in the same manner as in Example 28 except for performing. Moreover, pH of the aqueous solution of process (E) was adjusted by adding sulfuric acid of lean concentration. After the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points to investigate the maximum and minimum values. The results are shown in Table 7. When pH of the aqueous solution of process (E) was 5.0-10.0, the difference of the film thickness maximum value and the film thickness minimum value was small, and the in-plane uniformity after thin film formation was favorable. In Example 67 in which the pH of the aqueous solution of the step (E) was 10.3, it was confirmed that the difference between the maximum film thickness and the minimum film thickness was slightly large, resulting in a deterioration in in-plane uniformity after thinning.

In addition, in order to examine the presence or absence of the solder resist residue in the roughening surface of the connection pad exposed by the thin film formation process, the electroless nickel plating process was performed with respect to the exposed copper surface. Moreover, plating pretreatment was performed as needed, and when there existed a residue, the removal property was also investigated. The results are shown in Table 7. When the liquid temperature of the aqueous solution of a process (E) is 22-50 degreeC, there exists a tendency for residue residue of a soldering resist component to hardly generate | occur | produce with temperature rise, and residue residue was not confirmed at 27 degreeC or more. In Example 68, Example 76, and Example 86 whose liquid temperature of the aqueous solution of a process (E) is 20 degreeC, the tendency which the residue of a soldering resist component becomes easy to remain was confirmed.

(Examples 92 to 93)

In order to investigate the stability of a continuous thin film formation process, in the thin film formation process of a soldering resist layer, it uses the aqueous alkali solution (25 degreeC) of Table 8, and also uses the aqueous solution of the process (E) shown in Table 8 before washing with water. A soldering resist pattern was formed in the same manner as in Example 2 except that the spray treatment (spray pressure 0.20 MPa) was performed. During the continuous thinning treatment, the pH of the aqueous solution of the step (E) was not adjusted for each sheet treatment. In the first sheet and the tenth sheet of the thinning treatment, the thickness of the solder resist layer of the thinned portion was measured by 10 points. Maximum and minimum values were investigated. A result is shown in Table 9 with the value of pH of the aqueous solution of process (E). In Examples 2 and 20 in which the thin film was formed by washing with water after treatment with an aqueous alkali solution, the difference between the maximum film thickness and the minimum film thickness increases with the increase in the number of thin film treatments, and the in-plane uniformity after thin film deteriorates. There was this. In Example 92 and Example 93 which performed the process (E) before the water washing process, since the aqueous solution of a process (E) has a buffering capacity, pH of this aqueous solution after 10 sheets of thin film formation process is less than 10, and the film thickness maximum value In-plane uniformity after thin film formation was favorable also in the difference between the minimum and film thickness minimum values.

(Example 94)

In the thinning process of the soldering resist layer, the soldering resist pattern was formed by the method similar to Example 2 except having performed the spraying process which sprays aqueous alkali solution by spray pressure of 0.1 Mpa. The spray injection time was adjusted so that the thickness of the soldering resist layer after thinning might be 12 micrometers on average. When supplying aqueous alkali solution by spray injection, the bubble generate | occur | produced in large quantity in aqueous alkali solution adhered to the surface of the solder resist layer which should be thinned, and the thick-film part which is not locally thinned was confirmed as film thickness nonuniformity. Therefore, the spray pressure is lowered to 0.03 MPa so as not to generate bubbles, and the bubble trap filter is also disposed in the recovery path after the aqueous alkali solution is sprayed. As a result, the local film thickness nonuniformity generated above is not a problem in practical use. Has been reduced.

Industrial availability

The formation method of the soldering resist pattern of this invention is applicable to the use which forms a soldering resist pattern in the circuit board provided with the connection pad for flip chip connection, for example.

1 insulating substrate
2 conductor wiring
3 solder resist layer
4 Photomask
5 active rays
6 connection pads

Claims

(A1) Process of forming a soldering resist layer on the surface of a circuit board which has a connection pad,
(B1) Process of thinning until the thickness of a soldering resist layer becomes below the thickness of a connection pad by aqueous alkali solution
The method of forming a soldering resist pattern comprising the above in this order.

(A2) Process of forming a soldering resist layer on the surface of the circuit board which has a connection pad and conductor wiring,
(C) exposing portions other than the region to be thinned until the thickness of the solder resist layer becomes equal to or less than the thickness of the connection pad,
(B2) Process of thinning a soldering resist layer until the thickness of the soldering resist layer of a non-exposure part becomes below the thickness of a connection pad by aqueous alkali solution.
Forming method of a solder resist pattern comprising a.

3. The method of claim 2,
Between (A2) process and (C) process,
(D) Process of thinning solder resist layer whole surface by aqueous alkali solution
A method of forming a solder resist pattern comprising a.

(A3) Process of forming a soldering resist layer on the surface of a circuit board which has a connection pad and conductor wiring lower than a connection pad,
(B3) Process of thinning until the thickness of a soldering resist layer is below the thickness of a connection pad, and becomes thicker than the thickness of a conductor wiring by aqueous alkali solution.
The method of forming a soldering resist pattern comprising the above in this order.

The method according to any one of claims 1 to 4,
The aqueous alkali solution is an aqueous solution containing an inorganic alkaline compound, and the formation method of the soldering resist pattern whose content of this inorganic alkaline compound is 3-25 mass%.

The method of claim 5, wherein
A method for forming a soldering resist pattern, wherein the inorganic alkaline compound is at least one selected from alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides and alkali metal silicates.

The method of claim 5, wherein
The method of forming a soldering resist pattern, wherein the inorganic alkaline compound is an alkali metal silicate.

The method of claim 7, wherein
The method of forming a soldering resist pattern, wherein the alkali metal silicate is sodium metasilicate.

The method of claim 5, wherein
The method of forming a soldering resist pattern, wherein the inorganic alkaline compound is an alkali metal phosphate.

The method of claim 9,
The formation method of the soldering resist pattern whose alkali metal phosphate is at least 1 sort (s) chosen from trisodium phosphate and tripotassium phosphate.

The method of claim 5, wherein
The method of forming a soldering resist pattern whose inorganic alkaline compound is potassium carbonate.

The method according to any one of claims 1 to 4,
The formation method of the soldering resist pattern which is an aqueous solution in which aqueous alkali solution contains an organic alkaline compound.

13. The method of claim 12,
The formation method of the soldering resist pattern whose content of an organic alkaline compound is 5-25 mass%.

14. The method according to any one of claims 1 to 13,
The formation method of the soldering resist pattern whose pH of aqueous alkali solution is 12.5 or more.

15. The method according to any one of claims 1 to 14,
After the process of thinning a soldering resist layer with aqueous alkali solution,
(E) Process which contains alkaline compound, and content of this alkaline compound is less than aqueous alkali solution, and processes by aqueous solution of pH 5.0-10.0, temperature 22-50 degreeC
A method of forming a solder resist pattern comprising a.

The method according to any one of claims 1 to 15,
The process of thinning a soldering resist layer with aqueous alkali solution is a formation method of the soldering resist pattern by immersion process.