TWI675256B - Process for forming solder resist patterns - Google Patents

Abstract

The invention provides a method for forming a solder resist pattern capable of manufacturing a circuit substrate which does not generate residue of solder resist on a connection pad and has excellent electrical connection reliability. A method for forming a solder resist pattern includes, at least in sequence, the steps of forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning the uncured solder resist layer to a thickness of the solder resist layer to the thickness of the connection pad. A step up to the thickness; characterized in that the solder resist layer contains at least (A) a polymer containing a carboxyl group, (B) a polymerizable compound, (C) a filler, and (D) a photopolymerization initiator, (A The polymer having a carboxyl group has an acid value of 80 to 150 mgKOH / g or the average particle diameter of the (C) filler is 1.1 times or more the surface roughness Ra on the connection pad.

Description

Method for forming solder resist pattern

The present invention relates to a method for forming a solder resist pattern.

In order to prevent the solder from adhering to the conductor circuit of the circuit board that does not need to be adhered to the solder on a circuit board inside various electrical equipment, a solder resist pattern is formed to cover the conductor circuit that does not need to be adhered with a solder resist layer. In addition, the solder resist pattern plays a role in preventing oxidation of the conductor circuit, electrical insulation, and protection from the external environment.

In a semiconductor package in which electronic components such as a semiconductor wafer are mounted on a circuit board, mounting of electronic components connected using a flip chip is an effective method for achieving high speed and high density. In the flip-chip connection, a part of the conductor circuit becomes a connection pad for flip-chip connection. For example, a solder bump disposed on such a connection pad is bonded to an electrode terminal of an electronic component.

As a method of forming a solder resist pattern for a circuit board, a photolithography method is generally known. In the photolithography method, a solder resist layer is formed on a circuit substrate having a connection pad 6 and a conductor circuit 2 on the insulating layer 1 After 3, exposure and development are performed, the solder resist layer 3 around the connection pad 6 is removed, and an opening is provided to form a Solder Mask Defined (SMD) structure shown in FIG. 1 or FIG. 2 The Non Solder Mask Defined (NSMD) structure shown.

In the SMD structure shown in FIG. 1, since the vicinity of the periphery of the connection pad 6 is covered with the solder resist layer 3, in order to reliably electrically connect the electrode terminals of the electronic component and the connection pad 6, it is necessary to ensure that the connection pad 6 There is a problem that the amount of solder required for the joint portion formed by the exposed surface of the exposed surface increases the size of the connection pad 6. In addition, in order to reliably cover the vicinity of the periphery of the connection pad 6 with the solder resist layer 3, it is necessary to consider the processing accuracy, and ensure the width of the portion of the connection pad 6 covered with the solder resist layer 3 in advance. The problem of further scale-up. On the other hand, in the connection pad 6 of the NSMD structure shown in FIG. 2, since the connection pad 6 is entirely exposed on the solder resist layer 3, the connection area with the solder is large, and the connection can be made in comparison with the case of the SMD structure. The gasket 6 is miniaturized. However, in the NSMD structure, since the connection pads 6 are completely exposed on the solder resist layer 3, an electrical short caused by the solder may occur between the connection pads 6 adjacent to each other.

Some people have proposed a method for forming a solder resist pattern to solve such a problem. This method at least includes the steps of forming a solder resist layer 3 on a circuit substrate having a connection pad 6 and uncured solder resist layer. Step 3 to reduce the thickness until the thickness of the solder resist layer 3 becomes the thickness of the connection pad 6 or less (for example, refer to Patent Documents 1 to 2). In this method of forming a solder resist pattern, as shown in FIG. 3, the following structure is obtained: a connection pad The surface of the sheet 6 is exposed to the solder resist layer 3, but a part of the side surface of the connection pad 6 is covered with the solder resist layer 3. In the structure shown in FIG. 3, it is difficult to generate an electrical short circuit caused by the solder between the adjacent connection pads 6, and the amount of solder required to electrically connect the electrode terminals of the electronic parts and the connection pads 6 can be ensured. The connection pad 6 can be miniaturized, and a circuit board for a high-density circuit having excellent electrical connection reliability can be manufactured.

In such a method of forming a solder resist pattern, there are problems as described below with regard to an alkali-developed solder resist.

First, an alkali developing type solder resist adjusts an acid value by containing a polymer having a carboxyl group, and develops alkali developing property. However, in a solder resist which requires insulation reliability, it is necessary to use a polymer having a low acid value by reducing the carboxyl group content. When a solder resist containing a polymer having a low acid value is used in this way, if a solder resist pattern is formed by the method disclosed in Patent Documents 1 to 2, residues of the solder resist are generated on the connection pads. Cases where the reliability of the electrical connection is adversely affected.

Second, in order to improve the adhesion between the surface of the conductor circuit 2 and the solder resist layer 3, a method of roughening the surface of the conductor circuit 2 to produce an anchor effect is generally known. In the roughening process of the surface of the conductor circuit 2, the surface of the conductor circuit 2 is micro-etched using an etchant, thereby roughening the surface of the conductor circuit 2. Since the connection pad 6 is a part of the conductor circuit 2, the surface of the connection pad 6 is also roughened.

The solder resist usually contains a filler. With the filler, the curing shrinkage of the solder resist layer 3 is suppressed, and adhesion, hardness, and the like are improved. Conversely, a decrease in the visibility or a decrease in the resolution due to an increase in light scattering is also caused. The problem. For this reason, in a solder resist which is required to form a high-definition solder resist pattern, it is necessary to use a filler having a small particle diameter.

However, if a solder resist containing a filler having a small particle diameter is used and the solder resist pattern is formed by the method disclosed in Patent Documents 1 and 2, a filler is filled in the recessed portion of the roughened connection pad 6 surface. Situation. The thickness of the solder resist layer 3 around the filler filled in the recessed portion on the surface of the connection pad 6 becomes thinner than usual. As a result, residues of the solder resist are generated on the surface of the connection pad 6, which may adversely affect the reliability of the electrical connection.

[Prior Art Literature] [Patent Literature]

[Patent Document 1]: Japanese Patent Application Laid-Open No. 2011-192692

[Patent Document 2]: International Publication No. 2012/043201.

An object of the present invention is to provide a method for forming a solder resist pattern, which at least sequentially includes the steps of forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning an uncured solder resist layer to the solder resist. The thickness of the layer becomes a step below the thickness of the connection pad; the method can produce a circuit board having no solder resist residue on the connection pad and excellent in electrical connection reliability.

The inventors have found that the above problems can be solved by the following methods.

(1) A method for forming a solder resist pattern, which at least includes the steps of forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning an uncured solder resist layer to a thickness of the solder resist layer to A step up to the thickness of the connection pad, wherein the solder resist layer contains at least (A) a carboxyl group-containing polymer, (B) a polymerizable compound, (C) a filler, and (D) a photopolymerization initiator, The acid value of the (A) carboxyl group-containing polymer is 80 to 150 mgKOH / g.

(2) A method for forming a solder resist pattern, which at least includes the steps of forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning the uncured solder resist layer to a thickness of the solder resist layer to A step up to the thickness of the connection pad, wherein the solder resist layer contains at least (A) a carboxyl group-containing polymer, (B) a polymerizable compound, (C) a filler, and (D) a photopolymerization initiator, Therefore, the average particle diameter of the (C) filler is 1.1 times or more the surface roughness Ra on the connection pad.

In the following description, the method of (1) and the method of (2) are referred to as "the present invention 1" and "the present invention 2", and the methods of (1) and (2) are collectively referred to as the "invention" ".

According to the present invention, the step of forming a solder resist layer on a circuit substrate having at least a connection pad is included at least in order, In the method of forming a solder resist pattern in which the thickness of the solder layer is reduced until the thickness of the solder resist layer becomes equal to or less than the thickness of the connection pad, the residue of the solder resist does not occur on the connection pad, and the electrical connection reliability can be produced. Excellent circuit board.

1‧‧‧ insulation

2‧‧‧ conductor circuit

3‧‧‧solder resist layer

4‧‧‧Mask

5‧‧‧ Active light

6‧‧‧Connecting gasket

1 is a schematic view showing a cross-sectional structure (SMD structure) of a solder resist pattern.

FIG. 2 is a schematic diagram showing a cross-sectional structure (NSMD structure) of a solder resist pattern.

3 is a schematic view showing an example of a cross-sectional structure of a solder resist pattern formed by the method for forming a solder resist pattern of the present invention.

4 is a schematic diagram showing an example of steps in a method of forming a solder resist pattern according to the present invention.

5 is a schematic view showing an example of steps in a method of forming a solder resist pattern of the present invention.

[Best Mode for Carrying Out the Invention]

The method for forming a solder resist pattern of the present invention includes, at least in sequence, forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning the uncured solder resist layer to a thickness of the solder resist layer to a connection pad. The thickness of the sheet follows the steps.

A method for forming a solder resist pattern of the present invention will be described with reference to FIG. 4. On a circuit substrate (FIG. 4a) having a connection pad 6 on the insulating layer 1, a solder resist layer 3 is formed to cover the entire circuit substrate (FIG. 4b). Next, by thinning the uncured solder resist layer 3 until the thickness of the solder resist layer 3 becomes less than the thickness of the connection pad 6, as shown in FIG. 4d, the surface of the connection pad 6 is formed to be exposed on the solder resist layer 3. Solder mask pattern.

A method for forming a solder resist pattern according to another embodiment of the present invention will be described with reference to FIG. 5. A solder resist layer 3 is formed on the circuit substrate (FIG. 5a) having the conductor circuit 2 and the connection pad 6 on the insulating layer 1 to cover the entire circuit substrate (FIG. 5b). Next, a portion (unthinned portion) other than the area where the thickness of the solder resist layer 3 becomes the thickness of the connection pad 6 or less is exposed by the active light 5 to cure the solder resist layer 3 (FIG. 5c). ). In FIG. 5 c, exposure is performed through the mask 4, but exposure may also be performed by a direct drawing method. Next, by thinning the uncured solder resist layer 3 until the thickness of the solder resist layer 3 becomes less than the thickness of the connection pad 6, as shown in FIG. 5d, the surface of the connection pad 6 is formed to be exposed on the solder resist layer 3. Solder mask pattern.

In addition to the method of forming the solder resist pattern shown in FIGS. 4 and 5, in the present invention, the order of each step, the number of times of each step, and the conditions of each step (such as the exposed portion, the amount of thin film, the resistance Thickness of the solder layer when it is formed, etc.), a step of forming the solder resist layer 3 on the circuit board, a step of thinning the solder resist layer 3, a step of exposing the solder resist layer 3 by active light, and completely removing uncured By combining the developing steps and the like of the solder resist layer 3, a solder resist pattern having various structures can be formed.

In the present invention, the circuit board includes an insulating layer 1 and a connection pad 6 formed on a surface of the insulating layer 1. A conductor circuit 2 is formed on the surface of the insulating layer 1, and the connection pad 6 is a part of the conductor circuit 2. In the present invention, the circuit substrate has a solder resist pattern formed by the solder resist layer 3 on the surface of the circuit substrate, and a part of the connection pad 6 is exposed on the solder resist layer 3. In the case of a circuit board on which electronic components are mounted, the connection pads 6 on one surface are used for connection of electronic components, and the connection pads 6 on the other surface are used for external connection. The connection pad 6 for electronic component connection is bonded to the electronic component, and the connection pad 6 for external connection is bonded to the conductor circuit of the external electrical substrate.

4 and 5 which are schematic views showing an example of the steps in the solder resist pattern forming method of the present invention, and which are one of the cross-sectional structures of the solder resist pattern formed by the solder resist pattern forming method of the present invention. In the schematic diagram of the example, FIG. 3 shows a circuit board having an insulating layer 1 and a connection pad 6 on one surface of the insulating layer 1, but the circuit board according to the present invention includes a conductor circuit arranged therein An insulating substrate or a conductive circuit for build-up is alternately laminated on an insulating substrate, and has a surface of the insulating layer 1 and a connection pad 6 formed on the surface of the insulating layer 1.

Examples of the insulating substrate include a resin substrate made of an electrical insulating material such as a glass cloth impregnated with a thermosetting resin such as a bismaleimide triazine resin or an epoxy resin. Examples of the insulating layer for build-up include an electrical insulating material impregnated with a thermosetting resin in a glass cloth in the same manner as an insulating substrate, and a thermosetting resin such as an epoxy resin. Electrical insulation materials in which inorganic fillers such as silicon oxide are dispersed.

The conductor circuit 2 and the connection pad 6 can be formed by, for example, a deletion method, a semi-additive method, or an additive method. In the erasing method, for example, a resist pattern is formed on a copper layer provided on the insulating layer 1, and exposure, development, etching, and resist peeling are performed to form a conductor circuit 2 and a connection pad 6. In the semi-additive method, a base metal layer for electrolytic copper plating is provided on the surface of the insulating layer 1 by non-electrolytic copper plating. Next, a plating resist pattern is formed on the base metal layer, and an electrolytic copper plating layer is formed on the surface of the exposed base metal layer. Thereafter, peeling of the plating resist and flash etching of the underlying metal layer are performed to form the conductor circuit 2 and the connection pad 6.

The solder resist layer 3 according to the present invention includes at least (A) a carboxyl group-containing polymer, (B) a polymerizable compound, (C) a filler, and (D) a photopolymerization initiator.

As the solder resist according to the present invention, an alkali developing type solder resist can be used. In addition, it may be a one-component, two-component, any one of a liquid solder resist, or a dry film solder resist.

As the (A) carboxyl group-containing polymer according to the present invention, a polymer having a carboxyl group in a molecule can be used. The carboxyl group-containing polymer further having an ethylenically unsaturated double bond in the molecule can be crosslinked together with the (B) polymerizable compound, and it is more preferable from the viewpoint of curability and resistance of the solder resist layer 3 after curing to an alkaline aqueous solution. Specific examples include the polymers listed below.

(1) An unsaturated carboxylic acid such as (meth) acrylic acid, which is obtained by copolymerizing one or more kinds of compounds having an unsaturated double bond other than these Polymers with carboxyl groups.

(2) A carboxyl group-containing polymer obtained by using a compound having an epoxy group and an unsaturated double bond or (meth) acrylic acid, chloro, or the like, with an ethylenically unsaturated group as a side group and (methyl ) Addition of a copolymer of an unsaturated carboxylic acid such as acrylic acid and one or more other compounds having an unsaturated double bond.

(3) A carboxyl group-containing polymer obtained by a method in which an unsaturated carboxylic acid such as (meth) acrylic acid is compounded with a compound having an epoxy group and an unsaturated double bond, and a compound having an unsaturated double bond other than that The copolymer of the compound is reacted to react the polybasic acid anhydride with the secondary hydroxyl group formed.

(4) A carboxyl group-containing polymer obtained by a method in which a compound having a hydroxyl group and an unsaturated double bond and an acid anhydride having an unsaturated double bond such as maleic anhydride, and a compound having an unsaturated double bond other than these Copolymer reaction.

(5) A carboxyl group-containing polymer obtained by reacting a polyfunctional epoxy compound with an unsaturated monocarboxylic acid such as (meth) acrylic acid, and causing a saturated polybasic acid anhydride or unsaturated polybasic acid anhydride to react with the produced reactant. In the reaction of hydroxyl groups.

(6) A hydroxyl-containing carboxyl group-containing polymer obtained by a method in which a saturated polybasic acid anhydride or an unsaturated polybasic acid anhydride is reacted with a hydroxyl-containing polymer such as a polyvinyl alcohol derivative, and then epoxy is contained in one molecule. Compounds in which the group has an unsaturated double bond react with the carboxylic acid formed.

(7) A carboxyl group-containing polymer obtained by the following method: a polyfunctional epoxy compound, an unsaturated monocarboxylic acid such as (meth) acrylic acid, It reacts with a compound (for example, dimethylolpropionic acid, etc.) having at least one alcoholic hydroxyl group and one reactive group other than the alcoholic hydroxyl group that reacts with an epoxy group in one molecule, and the saturated polybasic acid anhydride or unsaturated polybasic acid anhydride is reacted with The obtained reaction product reacts.

(8) A carboxyl group-containing polymer obtained by: combining an unsaturated monocarboxylic acid such as (meth) acrylic acid with a polyfunctional oxetane having at least two oxetane rings in one molecule; The alkane compound is reacted to obtain a modified oxetane resin, and a saturated polybasic acid anhydride or an unsaturated polybasic acid anhydride is reacted with a primary hydroxyl group in the obtained modified oxetane resin.

(9) A carboxyl group-containing polymer obtained by reacting an unsaturated monocarboxylic acid (e.g., (meth) acrylic acid, etc.) with a polyfunctional epoxy resin (e.g., cresol-type epoxy resin, etc.) And react with a polybasic acid anhydride (such as tetrahydrophthalic anhydride) to obtain a polymer containing a carboxyl group, and further make a compound (e.g., shrink) having one ethylene oxide ring and one or more ethylenically unsaturated groups in the molecule Glyceryl (meth) acrylate, etc.) are reacted therewith.

(A) The carboxyl group-containing polymer is not limited to the polymers listed above. In addition, these can be used individually by 1 type or in combination of 2 or more types.

Among the above-listed polymers, preferred polymers are the carboxyl group-containing polymers (2), (5), (7), and (9) described above, particularly from the properties of curability and the solder resist layer after curing. From the point of view, the carboxyl group-containing polymer of the above (9) is more preferable.

Moreover, in the present invention, (meth) acrylic acid is a mixture of acrylic acid, A collective term for methacrylic acid and these mixtures. (Meth) acrylate is a term collectively referred to as acrylate, methacrylate, and mixtures thereof. Examples of the compound having an epoxy group and an unsaturated double bond include glycidyl (meth) acrylate, 3,4-epoxycyclohexyl methyl (meth) acrylate, and the like. Examples of the compound having a hydroxyl group and an unsaturated double bond include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

Since the (A) carboxyl group-containing polymer described above has a large number of free carboxyl groups in the side chain of the backbone. Polymer (main chain), it can be formed into a thin film by an aqueous alkali solution or developed by a dilute aqueous alkali solution.

In the present invention 1, the acid value of the (A) carboxyl group-containing polymer ranges from 80 to 150 mgKOH / g, and preferably ranges from 90 to 120 mgKOH / g. When the acid value of the (A) carboxyl group-containing polymer is less than 80 mgKOH / g, residues of the solder resist are liable to be generated on the connection pad 6 and it may become difficult to ensure the reliability of electrical connection. On the other hand, if it exceeds 150 mgKOH / g, in the step of thinning the solder resist layer 3, the solder resist layer 3 or the thinned solder resist layer 3 in the exposed portion will easily swell, and the insulation with the solder resist pattern will be reliable. Sexual decline. When the acid value of the (A) carboxyl group-containing polymer is in the range of 80 to 150 mgKOH / g, a circuit board having excellent electrical connection reliability and insulation reliability is easily obtained.

(A) The mass average molecular weight of the carboxyl group-containing polymer is preferably 5,000 to 150,000, and more preferably 10,000 to 100,000. If the mass-average molecular weight is less than 5,000, the resistance of the solder resist layer 3 after curing to an alkaline aqueous solution tends to decrease; on the other hand, if it exceeds 150,000, the time required for thinning tends to become longer.

With respect to the solder resist layer 3, the blending amount of the (A) carboxyl group-containing polymer is preferably 40 to 65% by mass, and more preferably 45 to 55% by mass. When the blending amount of the (A) carboxyl group-containing polymer is less than 40% by mass, the chemical and mechanical strengths of the solder resist layer 3 after curing tend to be lowered. In addition, the coating properties tend to be deteriorated. When the blending amount of the (A) carboxyl group-containing polymer exceeds 65% by mass, the polymerizability may decrease.

The (B) polymerizable compound according to the present invention is a compound which is insoluble in an alkaline aqueous solution or a compound which assists insolubilization by curing the solder resist layer 3 by photopolymerization by irradiating active light. Examples of such compounds include di (meth) acrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; hexanediol, trimethylolpropane, and pentaerythritol Polyhydric alcohols such as dipentaerythritol, trihydroxyethyl isocyanurate, etc., or poly (meth) acrylates such as ethylene oxide adducts or propylene oxide adducts, and (meth) acrylic phenoxy Esters, bisphenol A di (meth) acrylate, poly (meth) acrylates such as ethylene oxide adducts or propylene oxide adducts of these phenols, glycerol diglycidyl ether, triglyceride Polyglycidyl ethers of glycidyl ethers such as glycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate, and melamine (meth) acrylate.

The blending amount of the (B) polymerizable compound is preferably 5 to 100 parts by mass, and more preferably 5 to 70 parts by mass, with respect to 100 parts by mass of the (A) carboxyl group-containing polymer. When the blending amount of the (B) polymerizable compound is less than 5 parts by mass, the curability is lowered, and it may become difficult to form a solder resist pattern by irradiating active light and thin film, or it may no longer function. Solder resist Circumstances where the pattern protects against external environmental damage. On the other hand, when it exceeds 100 mass parts, the time required for thinning may become long, or the solder resist layer 3 after hardening may become brittle.

As the (C) filler, an inorganic filler or an organic filler can be used. Particularly, barium sulfate, silicon dioxide, and talc are preferably used, and these may be blended alone or two or more of these may be blended. The average particle diameter of the filler is preferably in a range of 0.1 to 20 μm. The average particle diameter is more preferably 0.2 μm or more, more preferably 4 μm or less, and even more preferably 2 μm or less.

In addition, the surface of the conductor circuit 2 may be roughened by an etchant in order to improve the adhesion with the solder resist layer 3. At this time, since the connection pad 6 is a part of the conductor circuit 2, the surface of the connection pad 6 is also roughened. When the solder resist layer 3 is formed on the connection pad 6 subjected to the roughening treatment in this manner, a filler is filled in the unevenness on the surface of the connection pad 6 formed by the roughening. The thinning speed of the solder resist layer 3 around the filler filled in the irregularities tends to be slower than usual. As a result, residues of the solder resist may be generated on the surface of the connection pad 6. Therefore, in order to avoid generation of residue, the average particle diameter of the filler is preferably in a range of 0.1 to 20 μm.

In addition, I pay attention to the combination of the roughness of the connection pad 6 and the average particle diameter of the filler. In the present invention 2, the average particle diameter of the (C) filler is the surface roughness Ra of the connection pad 6 1.1 times or more. (C) The average particle diameter of the filler is preferably 1.2 times or more, and more preferably 1.3 times or more, relative to the surface roughness Ra on the connection pad 6. Since the solder resist layer 3 contains an average particle diameter of 1.1 as the surface roughness Ra on the connection pad 6 The filler (C) that is twice or more does not cause residues of the solder resist layer 3 on the connection pad 6, and therefore it is easy to obtain a circuit board for a high-density circuit that ensures insulation reliability and is excellent in electrical connection reliability.

The average particle diameter in the present invention is a D50 (50% particle diameter based on volume) measured by a laser diffraction scattering method.

The blending amount of the filler (C) is preferably 300 parts by mass or less, more preferably 0.1 to 300 parts by mass, and still more preferably 0.1 to 150 parts by mass with respect to 100 parts by mass of the (A) carboxyl group-containing polymer. . When the blending amount of the (C) filler exceeds 300 parts by mass, the viscosity of the coating liquid or liquid solder resist used to produce the dry film solder resist becomes higher, and the coating properties may be reduced or after curing. The case where the solder resist layer 3 becomes brittle.

From the viewpoint of the dispersibility in the solder resist layer 3 or the influence on the resolution, the shape of the (C) filler is preferably spherical.

Examples of the etchant used for roughening the surface of the conductor circuit 2 include treatment agents containing hydrogen peroxide, sulfuric acid, benzotriazoles, and chloride ions; hydrogen peroxide, inorganic acids, triazoles, tetrazolium, and the like. Treatment agents such as azoles, imidazoles; treatment agents containing halide ion sources; treatment agents containing oxyacids, peroxides, azoles and halides; hydrogen peroxide, inorganic acids, triazoles, tetrazoles and / or Treatment agent of imidazole and surfactant; treatment agent containing hydrogen peroxide, sulfuric acid, phenyltetrazole, chloride ion source; treatment containing hydrogen peroxide, sulfuric acid, aminotetrazole, tetrazole compound, phosphonic acid chelating agent A treatment agent composed of an aqueous solution containing a main agent and an auxiliary agent, the main agent being composed of an inorganic acid and copper oxidizing agent, and the auxiliary agent being composed of an azole and an etching inhibitor.

Examples of the (D) photopolymerization initiator include benzoin and its alkyl ethers such as benzoin, benzoin methyl ether, and benzoin ethyl ether, and acetophenone and 2,2-dimethoxy-2-phenylacetophenone. , Acetophenones such as 1,1-dichloroacetophenone, 4- (1-tert-butyldioxy-1-methylethyl) acetophenone, 2-methylanthraquinone, 2-pentyl Anthraquinones such as 2-anthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2-chlorothioxanthone Thioxanthone such as ton ketone, ketal such as acetophenone dimethyl ketal, benzyl dimethyl ketal, benzophenone, 4- (1-tert-butyldioxy-1- Methyl ethyl) benzophenones, benzophenones such as 3,3 ', 4,4'-tetrakis (t-butyldioxycarbonyl) benzophenone and the like.

Moreover, as a preferable (D) photoinitiator, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-acetone, 2-benzyl, etc. are mentioned. Methyl-2-dimethylamino-1- (4-morpholinophenyl) -but-1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, N, N-dimethylaminoacetophenone (as a commercially available product, Irgacure (registered trademark) 907 manufactured by BASF Corporation, Α-aminoacetophenones such as Irgacure (registered trademark) 369, Irgacure (registered trademark) 379, etc., 2,4,6-trimethylbenzylidene diphenylphosphine oxide, bis (2,4,6 -Trimethylbenzylidene) -phenylphosphine oxide, bis (2,6-dimethoxybenzylidene) -2,4,4-trimethyl-pentylphosphine oxide (as a commercially available product) , Fluorenyl phosphine oxides such as Lucirin (registered trademark) TPO, Irgacure (registered trademark) 819, etc. manufactured by BASF Corporation.

The blending amount of the (D) photopolymerization initiator is 0.01 to 30 parts by mass, and preferably 0.5 to 15 parts by mass, with respect to 100 parts by mass of the (A) carboxyl group-containing polymer. With respect to 100 parts by mass of (A) a carboxyl group-containing polymer, When the blending amount of the (D) photopolymerization initiator is less than 0.01 parts by mass, the photocurability of the solder resist layer 3 may be insufficient, or the solder resist layer 3 may be peeled off, or the solder resist layer 3 such as chemical resistance may be used. When the characteristics are reduced. On the other hand, if the blending amount of the photopolymerization initiator exceeds 30 parts by mass with respect to 100 parts by mass of the (A) carboxyl group-containing polymer, deep curing may be reduced due to light absorption by the photopolymerization initiator. .

In the solder resist layer 3 according to the present invention, in order to improve the physical strength and the like of the solder resist layer 3, a thermosetting component may be blended as necessary. As such a thermosetting component, an amine-based resin such as a melamine resin, a phenylguanamine resin, a blocked isocyanate compound, a cyclic carbonate compound, a polyfunctional epoxy compound, a polyfunctional oxetane compound, and an episulfide can be used. Thermosetting resin such as bio-resin.

The blending amount of the thermosetting component may be a ratio generally used, for example, it is preferably 0.01 to 20 parts by mass with respect to (A) a carboxyl group-containing polymer and (B) a polymerizable compound in a total amount of 100 parts by mass. The thermosetting component can be used alone or in combination of two or more.

In addition, for the purposes of (A) synthesis of a carboxyl group-containing polymer, preparation of a liquid solder resist, preparation of a coating liquid for producing a dry film solder resist, adjustment of the viscosity of the liquid solder resist or the coating liquid, etc. An organic solvent may be used in the solder resist according to the present invention.

Examples of the organic solvent include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents.

More specific examples include methyl ethyl ketone, cyclohexanone, and the like. Ketones, aromatic hydrocarbons such as toluene, xylene, tetramethylbenzene, cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methylcarbitol, butylcarbitol, Glycol ethers such as propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, and dipropylene glycol Methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol butyl ether acetate and the like, alcohols, propanol, ethylene glycol, propylene glycol and the like Aliphatic hydrocarbons such as alkane and decane, petroleum solvents such as petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha. The organic solvent may be used alone or as a mixture of two or more.

The method of forming the solder resist layer 3 on the circuit substrate may be any method. For example, in the case of a liquid solder resist, a screen printing method, a roll coating method, a spray method, a dipping method, a curtain coating method, a bar coating method, an air knife method, a hot melt method, a gravure coating method, Brush coating method, offset printing method, etc. In the case of a dry film-like solder resist, a lamination method, a vacuum lamination method, and the like can be listed.

In the present invention, the step of thinning the solder resist layer 3 includes a micellization process (thinning process) of micellizing an uncured solder resist layer component with a thinning treatment solution (aqueous aqueous solution). This is followed by a micelle removal process using micelle removal liquid to remove micelles. In addition, the surface of the solder resist layer 3 which has not been completely removed or the remaining thin film-forming treatment solution and micelle removal solution may be rinsed by water washing, and a drying treatment may be performed to remove the water.

Thinning treatment (micellarization treatment) uses a thinning treatment liquid A process of micelleizing the solder resist layer component and temporarily dissolving the micelle in the thin film-forming treatment solution. The thin-film forming treatment liquid is a high-concentration alkaline aqueous solution. Examples of the basic compound used in the thin film-forming treatment liquid include inorganic bases such as alkali metal silicate, alkali metal hydroxide, alkali metal phosphate, alkali metal carbonate, ammonium phosphate, and ammonium carbonate. Sex compounds, monoethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide (TMAH), tetraethyl hydroxide Organic basic compounds such as ammonium and trimethyl-2-hydroxyethylammonium (choline). Examples of the alkali metal include lithium, sodium, and potassium. These basic compounds can be used alone or in combination of two or more. In addition, an inorganic basic compound and an organic basic compound may be used in combination.

The content of the basic compound is preferably 3 to 50% by mass based on the thin film-forming treatment solution. In addition, in order to thin the surface of the solder resist layer 3 more uniformly, sulfate and sulfite may be added to the thin film-forming treatment liquid. Examples of the sulfate or sulfite include alkali metal sulfates or sulfites such as lithium, sodium, and potassium; and alkaline earth metal sulfates or sulfites such as magnesium and calcium.

As the thinning treatment liquid, the surface can be more uniformly thinned, so it is particularly suitable for use: it contains at least one selected from inorganic basic compounds and organic basic compounds, and the content of the basic compound is 5 to 25 mass % Thin film treatment liquid, wherein the inorganic basic compound is selected from the group consisting of alkali metal carbonate, alkali metal phosphate, alkali metal hydroxide, and alkali metal silicate, and the organic basic compound is selected from TMAH and choline. If it is less than 5% by mass, the amount of film formation may become uneven. In addition, if it exceeds 25 As mass%, precipitation of the inorganic basic compound tends to occur with respect to the inorganic basic compound, and thus the stability of the thin-film treatment solution with time may become a problem. In the case of an organic basic compound, since the odor becomes strong, there is a case where operability becomes a problem. The content of the basic compound is preferably 7 to 17% by mass, and more preferably 8 to 13% by mass. The pH of the thin film-forming treatment liquid is set to 10 or more as compared with the home. In addition, a surfactant, an antifoaming agent, a solvent, and the like may be appropriately added.

The thinning treatment can be performed by a dipping treatment, a paddling treatment, a spray treatment, a brush application, or a scraping treatment, and the dipping treatment is preferred. Processing methods other than the immersion treatment tend to generate bubbles in the thin film-forming treatment liquid. Such generated bubbles may adhere to the surface of the solder resist layer 3 during the thin film processing, and the amount of the thin film may become uneven.

In the micellar removal process for removing micelles that do not dissolve the components of the solder resist layer that are insoluble in the thin film-forming treatment solution, the micelles are dissolved and removed by spraying the micelle removal solution.

Examples of the micelle removal liquid include tap water, industrial water, and pure water. In addition, by using the following aqueous solution as a micelle removal liquid, the component of the solder resist layer which is insoluble in the thin film-forming treatment liquid is easily redispersed: it contains at least 1 selected from inorganic basic compounds and organic basic compounds. An aqueous solution of pH 5 to 10, wherein the inorganic basic compound is selected from the group consisting of alkali metal carbonate, alkali metal phosphate, and alkali metal silicate, and the organic basic compound is selected from TMAH and choline. When the pH of the micelle removal liquid is lower than 5, the components of the solder resist layer aggregate and become insoluble mud, which may cause adhesion to the surface of the thinned solder resist layer 3. On the other hand, the micelle removal fluid When the pH value is higher than 10, the solder resist layer 3 is excessively dissolved and diffused, and it may become easy to cause unevenness in the amount of thin film in the surface. The micelle removal solution can be adjusted in pH using sulfuric acid, phosphoric acid, hydrochloric acid, or the like.

Spray conditions in the micelle removal process will be described. The spraying conditions (temperature, time, and spraying pressure) can be appropriately adjusted in accordance with the dissolution rate of the solder resist layer 3. Specifically, the processing temperature is preferably 10 to 50 ° C, and more preferably 15 to 35 ° C. In addition, the spray pressure is set to 0.01 to 0.5 MPa, and more preferably 0.1 to 0.3 MPa. For each 1 cm ² of the solder resist layer 3, the supply flow rate of the micelle removal liquid is preferably 0.030 to 1.0 L / min, more preferably 0.050 to 1.0 L / min, and still more preferably 0.10 to 1.0 L / min. When the supply flow rate is within this range, insoluble sludge does not remain on the surface of the solder resist layer 3 after thinning, and micelles can be removed substantially uniformly in the plane. If the supply flow rate per 1 cm ² is less than 0.030 L / min, poor dissolution of the insoluble solder resist layer components may occur. On the other hand, when the supply flow rate exceeds 1.0 L / min, parts such as a pump necessary for supply become huge, and a large-scale device may be required. In addition, at a supply flow rate exceeding 1.0 L / min, the effect of contributing to the dissolution and diffusion of the components of the solder resist layer may not change.

After the micelle removal treatment, the incompletely removed solder resist layer 3 or the remaining thin film-forming treatment liquid and micelle removal liquid remaining on the surface of the solder resist layer 3 may be washed by a water washing treatment. As a method of the water washing treatment, a spray method is preferred from the viewpoint of the diffusion rate and the uniformity of the liquid supply. As the washing water, tap water, industrial water, pure water, and the like can be used. Among them, pure water is preferably used. As the pure water, pure water generally used for industrial use can be used.

In the drying process, any one of hot air drying and room-temperature air blowing drying may be used. It is preferable to dry the high-pressure air by sending a large amount of air from an air gun or a blower and blowing off the water remaining on the surface of the solder resist layer 3 with an air knife.

In the method for forming a solder resist pattern of the present invention, the thickness of the solder resist layer 3 around the connection pad 6 is determined by the thickness after the solder resist layer 3 is formed and the amount of thinning the uncured solder resist layer 3. In addition, in the method for forming a solder resist pattern of the present invention, the amount of film formation can be freely adjusted within a range of 0.01 to 500 μm. The height from the thinned solder resist layer 3 to the top surface of the connection pad 6 is appropriately adjusted according to the required amount of solder. Specifically, the thickness of the top surface of the connection pad 6 is reduced to such a degree that a film thickness of 1 μm or more and 50 μm or less remains.

In the exposure of the step of exposing the solder resist layer 3, the solder resist layer 3 is irradiated with active light. Can be used: Xenon lamp, high-pressure mercury lamp, low-pressure mercury lamp, ultra-high-pressure mercury lamp, UV fluorescent lamp as the light source for exposure of the reflected image, single-sided, double-sided contact exposure using a photomask, or proximity, projection or Laser scanning exposure. In the case of scanning exposure, exposure can be performed by the following methods: UV laser, He-Ne laser, He-Cd laser, argon laser, krypton ion laser, ruby laser, YAG Laser light sources such as lasers, nitrogen lasers, pigment lasers, and excimer lasers are converted into scan exposures with SHG wavelengths, or scan exposures using liquid crystal shutters and micromirror array shutters. By exposure, the solder resist layer 3 is polymerized and cured.

The area until the thickness of the solder resist layer 3 becomes less than the thickness of the connection pad 6 as long as it is the size of the connection pad 6 or more. Yes, as long as it has no effect on the insulation resistance of the adjacent conductor circuit 2, it can be arbitrarily increased.

In the present invention, it is preferable to perform a step of curing the solder resist layer 3 (post-curing step) after the step of thinning the solder resist layer 3. Other steps may be included between the thinning step and the post-curing step. Through the post-curing step, the solder resist pattern can effectively prevent the oxidation of the conductor circuit, electrical insulation, and protection from the external environment. Examples of the curing treatment include a heat treatment, an exposure treatment for irradiating the entire solder resist layer with active light, and a combination of heating and exposure treatments. In the case of performing a heat treatment, it is preferred to select a temperature ranging from room temperature to 450 ° C in a nitrogen atmosphere for stepwise temperature increase, or a certain temperature range for continuous temperature increase, and perform the same for 5 minutes to 5 hours. The maximum temperature of the heat treatment is preferably 120 to 450 ° C, and more preferably 130 to 450 ° C. For example, heat treatment is performed at 130 ° C, 200 ° C, and 400 ° C for 30 minutes, respectively. In addition, heat treatment can be performed by linearly increasing the temperature from room temperature to 400 ° C. in 2 hours. In addition, a certain temperature can be selected and a heat treatment can be performed for a certain period of time.

[Example]

Hereinafter, the present invention will be described in more detail through examples, but the present invention is not limited to these examples.

[Example of the invention 1 concerning (A) acid value of a carboxyl group-containing polymer] Synthesis Example 1

Equipped with a stirrer, thermometer, reflux cooling tube, dropping funnel and nitrogen 660.0 parts by mass of a cresol novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: EOCN-104S), 432 parts by mass of carbitol acetate, and 188.0 parts by mass of a solvent were introduced into a separable flask in an introduction tube. Naphtha was heated to 90 ° C, stirred and dissolved. Next, after temporarily cooling to 60 ° C., 216 parts by mass of acrylic acid, 4.0 parts by mass of triphenylphosphine, and 1.3 parts by mass of methylhydroquinone were added, and the mixture was reacted at 100 ° C. for 12 hours. Then, 290.0 parts by mass of tetrahydrophthalic anhydride was added, and the mixture was heated to 90 ° C. and reacted for 6 hours. As a result, a solution of (A) a carboxyl group-containing polymer having a nonvolatile content of 65% by mass and a solid content acid value of 85 mgKOH / g was obtained. Hereinafter, the solution of this (A) carboxyl group-containing polymer is referred to as "polymer A-1". The acid value was measured in accordance with JIS K2501: 2003.

Synthesis Example 2

550.0 parts by mass of a cresol novolac epoxy resin (made by Nippon Kayaku Co., Ltd., trade name: EOCN-104S) was placed in a separable flask equipped with a stirrer, a thermometer, a reflux cooling tube, a dropping funnel, and a nitrogen introduction tube, 471.0 parts by mass of carbitol acetate and 221.0 parts by mass of solvent naphtha were heated to 90 ° C, stirred and dissolved. Next, after temporarily cooling to 60 ° C., 216 parts by mass of acrylic acid, 4.0 parts by mass of triphenylphosphine, and 1.3 parts by mass of methylhydroquinone were added, and the mixture was reacted at 100 ° C. for 12 hours. Then, 400.0 parts by mass of tetrahydrophthalic anhydride was added thereto, and the mixture was heated to 90 ° C. and reacted for 6 hours. Thus, a solution of the (A) carboxyl group-containing polymer having a nonvolatile content of 65% by mass and a solid content acid value of 116 mgKOH / g was obtained. This (A) solution of a polymer containing a carboxyl group is hereinafter referred to as "polymer A-2 ".

Synthesis Example 3

445.0 parts by mass of a cresol novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: EOCN-104S) was placed in a separable flask equipped with a stirrer, a thermometer, a reflux cooling tube, a dropping funnel, and a nitrogen introduction tube, 501.0 parts by mass of carbitol acetate and 237.0 parts by mass of solvent naphtha were heated to 90 ° C, stirred and dissolved. Next, after temporarily cooling to 60 ° C., 216 parts by mass of acrylic acid, 4.0 parts by mass of triphenylphosphine, and 1.3 parts by mass of methylhydroquinone were added, and the mixture was reacted at 100 ° C. for 12 hours. Then, 505.0 parts by mass of tetrahydrophthalic anhydride was added thereto, and the mixture was heated to 90 ° C. and reacted for 6 hours. As a result, a solution of (A) a carboxyl group-containing polymer having a nonvolatile content of 65% by mass and a solid content acid value of 146 mgKOH / g was obtained. Hereinafter, this (A) solution containing a carboxyl group-containing polymer is referred to as "polymer A-3".

Comparative Synthesis Example 1

700.0 parts by mass of a cresol novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: EOCN-104S) was placed in a separable flask equipped with a stirrer, a thermometer, a reflux cooling tube, a dropping funnel, and a nitrogen introduction tube, 432 parts by mass of carbitol acetate and 188.0 parts by mass of solvent naphtha were heated to 90 ° C, stirred and dissolved. Next, after temporarily cooling to 60 ° C., 216 parts by mass of acrylic acid, 4.0 parts by mass of triphenylphosphine, and 1.3 parts by mass of methylhydroquinone were added, and the mixture was reacted at 100 ° C. for 12 hours. Then, in 250.0 parts by mass of tetrahydrophthalic anhydride was added thereto, and the mixture was heated to 90 ° C. and reacted for 6 hours. Thus, a solution of a carboxyl group-containing polymer having a nonvolatile content of 65% by mass and a solid content acid value of 74 mgKOH / g was obtained. Hereinafter, this solution containing a carboxyl group-containing polymer is referred to as "comparative polymer a-1".

Comparative Synthesis Example 2

410.0 parts by mass of a cresol novolac epoxy resin (made by Nippon Kayaku Co., Ltd., trade name: EOCN-104S), into a separable flask equipped with a stirrer, a thermometer, a reflux cooling tube, a dropping funnel, and a nitrogen introduction tube, 511 parts by mass of carbitol acetate and 244.0 parts by mass of solvent naphtha were heated to 90 ° C, stirred and dissolved. Next, after temporarily cooling to 60 ° C., 216 parts by mass of acrylic acid, 4.0 parts by mass of triphenylphosphine, and 1.3 parts by mass of methylhydroquinone were added, and the mixture was reacted at 100 ° C. for 12 hours. Then, 540.0 parts by mass of tetrahydrophthalic anhydride was added thereto, and the mixture was heated to 90 ° C. and reacted for 6 hours. Thus, a solution of a carboxyl group-containing polymer having a non-volatile content of 65% by mass and a solid content acid value of 157 mgKOH / g was obtained. Hereinafter, this solution containing a carboxyl group-containing polymer is referred to as "comparative polymer a-2".

Each material was blended in the proportion (parts by mass) shown in Table 1. After pre-mixing with a stirrer, kneading was performed with a 3-axis roll mill to prepare the solder resists of Blending Examples 1 to 3 and Comparative Blending Examples 1 to 2.

(Examples 1 to 6 and Comparative Examples 1 to 4)

Using a resist erasing method, a copper-clad laminate (area: 170 mm × 200 mm, copper foil thickness: 18 μm, and substrate thickness: 0.4 mm) was fabricated on the insulation layer 1 with a conductor circuit width of 80 μm and a conductor circuit. A circuit board of the conductor circuit 2 with a distance of 80 μm. Next, use the applicator The solder resists of the blending examples 1 to 3 and the comparative blending examples 1 to 2 were applied to the above circuit boards, respectively, and dried at 70 ° C. for 30 minutes. Thus, a solder resist layer 3 having a dry film thickness of 35 μm from the surface of the insulating layer 1 to the surface of the solder resist layer 3 was formed on the circuit board.

Next, a portion corresponding to the start point and the end point of the conductor circuit 2 is regarded as a connection pad 6, and light having a pattern pattern that irradiates an active light ray 5 in an area 80 μm from the edge of the portion corresponding to the start point and the end point is used The mask 4 is exposed to the solder resist layer 3 with an energy of 200 mJ / cm ² using a close exposure machine.

Next, the alkali aqueous solution (thinning treatment liquid) shown in Table 2 was used for the immersion treatment at the processing times shown in Table 2. Then, tap water was used to perform micellar removal treatment and water washing, followed by drying treatment, and the uncured The thickness of the solder resist layer 3 is reduced until the thickness of the solder resist layer 3 in the non-exposed portion becomes 12 μm on average.

Next, post-cure was performed on the conditions of 150 degreeC and 60 minutes. Observe the formed solder resist patterns of Examples 1 to 6 and Comparative Examples 1 to 4 with a microscope. As a result, as shown in FIG. 3, a conductor circuit 2 having a height of 18 μm is covered with a solder resist layer 3 having a thickness of 35 μm. And the height of the connection pad 6 having a height of 18 μm is surrounded by a solder resist layer 3 having a thickness of 12 μm. Covered solder resist pattern.

In addition, the connection pads 6 and the solder resist layer 3 around the connection pads 6 in the solder resist patterns of Examples 1 to 6 and Comparative Examples 1 to 4 were observed with a microscope. As shown in Table 2, in Examples 1 to 6 in which the acid value of the (A) carboxyl group-containing polymer used was in the range of 80 to 150 mgKOH / g, it was confirmed that no solder resist residue was left on the connection pad 6. It was also confirmed that the solder resist layer 3 did not swell.

In contrast, in Comparative Examples 1 and 2 in which the acid value of the (A) carboxyl group-containing polymer used was less than 80 mgKOH / g, although the solder resist layer 3 did not swell, it was confirmed that the solder resist layer 3 was on the connection pad 6. There are residues of solder resist.

Moreover, in Comparative Examples 3 to 4 in which the acid value of the (A) carboxyl group-containing polymer used was more than 150 mgKOH / g, although the solder resist residue was not left on the connection pad 6, the solder resist layer 3 was confirmed to swell.

[Example of the present invention 2 concerning (C) average particle diameter of filler]

As the filler (C), fillers C1 to C4 made of amorphous silicon dioxide shown in Table 3 were used. The average particle diameter in the present invention is a D50 (50% particle diameter based on volume) measured by a laser diffraction scattering method.

Each material was blended in the ratio (parts by mass) shown in Table 4, and after pre-mixing with a stirrer, kneading was performed with a 3-axis roll mill to prepare the solder resists of Examples 4 to 7.

(Roughening treatment of copper clad laminate)

Using a cleaning agent (Mitsubishi Gas Chemical Company, Inc., trade name: CPE-700), a copper-clad laminate (area: 170 mm × 200 mm, copper foil thickness: 18 μm, substrate thickness: 0.4 mm) was used to remove the copper surface. Purification. Next, in a solution containing 1.5% by mass of hydrogen peroxide in water, The amount of sulfuric acid, 0.005% by mass of chloride ions, and 0.3% by mass of 1H-benzotriazole in an etchant (temperature: 30 ° C) were immersed in the copper-clad laminate, washed with water, and dried to obtain a copper-clad having a roughened copper surface. Laminated boards 1 ~ 4. The surface roughness of the copper surface was adjusted by changing the immersion time. Table 5 shows the surface roughness Ra of the obtained copper-clad laminates 1 to 4.

The surface roughness Ra is an arithmetic average surface roughness, and was obtained using a super-depth shape measuring microscope (manufactured by Keyence, product number "VK-8500") by a calculation formula based on JIS B0601-1994 surface roughness-definition. The measurement area was 900 μm ² and the reference length was 40 μm.

(Examples 7 to 30 and Comparative Examples 5 to 12)

A circuit board having a conductor circuit 2 having a conductor circuit width of 80 μm and a conductor circuit distance of 80 μm on the insulating layer 1 was prepared from the roughened copper-clad laminate by a removal method using a resist. Then, make Using the applicator, the solder resist of Blending Examples 4 to 7 was respectively coated on the circuit board, and dried at 70 ° C. for 30 minutes. Thus, a solder resist layer 3 having a dry film thickness of 35 μm from the surface of the insulating layer 1 to the surface of the solder resist layer 3 is formed on the circuit board.

Next, a portion corresponding to the start point and the end point of the conductor circuit 2 is regarded as a connection pad 6, and light having a pattern pattern that irradiates an active light ray 5 in an area 80 μm from the edge of the portion corresponding to the start point and the end point is used The mask 4 is exposed to the solder resist layer 3 with an energy of 200 mJ / cm ² using a close exposure machine.

Next, the alkaline aqueous solutions (thinning treatment liquids) 1 and 2 shown in Table 6 were used for the immersion treatment at the processing times shown in Table 6, and then tap water was used to perform micelle removal treatment and water washing, followed by drying treatment. The uncured solder resist layer 3 is thinned until the thickness of the solder resist layer 3 in the non-exposed portion becomes 12 μm on average.

Then, post-cure was performed at 150 ° C for 60 minutes. Into. The formed solder resist patterns of Examples 7 to 30 and Comparative Examples 5 to 12 were observed with a microscope. As a result, as shown in FIG. 3, a conductor circuit 2 having a height of 18 μm was covered with a solder resist layer 3 having a thickness of 35 μm. The surface of the connection pad 6 having a height of 18 μm is exposed, and the side of the connection pad 6 is covered with a solder resist layer 3 having a thickness of 12 μm.

In addition, in the solder resist patterns of Examples 7 to 30 and Comparative Examples 5 to 14, the connection pad 6 and the solder resist layer 3 around the connection pad 6 were observed with a microscope. As shown in Table 7, in Examples 7 to 30 in which the average particle diameter of the (C) filler used was 1.1 times or more the surface roughness Ra on the connection pad, it was confirmed that there was no solder resist on the connection pad 6. Residue. In contrast, in Comparative Examples 5 to 12 in which the average particle diameter of the (C) filler used was less than 1.1 times the surface roughness Ra on the connection pad, it was confirmed that there was a solder resist on the connection pad 6. Residue.

[Industrial availability]

The method for forming a solder resist pattern of the present invention is applicable to, for example, an application for forming a solder resist pattern on a circuit board having a connection pad for flip chip connection in a part of a circuit.

Claims (5)

A method for forming a solder resist pattern, which at least comprises the steps of forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning an uncured solder resist layer to a thickness of the solder resist layer to a connection pad. A step up to the thickness of the sheet, wherein the solder resist layer contains at least (A) a carboxyl group-containing polymer, (B) a polymerizable compound, (C) a filler, and (D) a photopolymerization initiator, (A) The acid value of the polymer containing a carboxyl group is 80 to 150 mgKOH / g. (C) The filler is selected from barium sulfate, silicon dioxide, and talc. The average particle diameter of the filler is in the range of 0.1 to 20 μm. The method for forming a solder resist pattern according to claim 1, wherein the average particle diameter of the (C) filler is 1.1 times or more the surface roughness Ra of the connection pad. A method for forming a solder resist pattern, which at least comprises the steps of forming a solder resist layer on a circuit substrate having at least a connection pad, and thinning an uncured solder resist layer to a thickness of the solder resist layer into a connection pad. A step up to the thickness of the sheet, wherein the solder resist layer contains at least (A) a carboxyl group-containing polymer, (B) a polymerizable compound, (C) a filler, and (D) a photopolymerization initiator, (C) The average particle diameter of the filler is 1.1 times or more the surface roughness Ra on the connection pad. The method for forming a solder resist pattern according to claim 3, wherein (A) the acid value of the polymer containing a carboxyl group is 80 to 150 mgKOH / g. For example, the method for forming a solder resist pattern of claim 3, wherein (C) the filler is selected from barium sulfate, silicon dioxide, and talc, and the average particle diameter of the filler is in a range of 0.1 to 20 μm.