JPWO2020158610A1 - Etching solution and etching method for resin composition - Google Patents

Abstract

Provided is an etching solution useful for an alkali-insoluble resin, a resin composition containing 20 to 40% by mass of an organic filler and 30 to 50% by mass of an inorganic filler, and the like. At least one selected from alcohol compounds and carboxylic acid compounds, containing 15 to 45% by mass of alkali metal hydroxide as the first component and 1 to 40% by mass of ethanolamine compound as the second component. An etching solution of a resin composition containing a third component, and an etching method using the etching solution.

Description

The present invention provides an etching solution (etching solution for a resin composition) and etching for etching an alkali-insoluble resin, a resin composition containing 20 to 40% by mass of an organic filler and 30 to 50% by mass of an inorganic filler. Regarding the method, etc.

In recent years, with the miniaturization and higher performance of electronic devices, it has been required to form fine wiring, reduce the coefficient of thermal expansion of insulating materials and substrate materials, reduce the dielectric constant, and reduce the dielectric loss tangent in circuit boards. .. Among them, as a means for lowering the coefficient of thermal expansion of the insulating material, a method of increasing the filling of the insulating material, that is, increasing the content of the inorganic filler in the insulating material is known. Further, it has been proposed to use an alkali-insoluble resin containing an epoxy resin, a phenol novolac-based curing agent, a phenoxy resin, a cyanate resin and the like as an insulating material and having excellent moisture resistance. As a means for lowering the dielectric constant and lowering the dielectric loss tangent of the insulating material, it is preferable to use a filler having a low relative permittivity, and it is known to use an organic filler such as fluororesin powder, for example. The insulating resin composition containing these inorganic fillers, organic fillers and alkali-insoluble resins has excellent physical properties such as heat resistance, dielectric properties, mechanical strength, and chemical resistance, and has excellent physical properties such as heat resistance, mechanical strength, and chemical resistance, and is the outer layer surface of the circuit board. It is widely studied as an interlayer insulating material used for solder resists used in the above and multilayer build-up wiring boards.

FIG. 1 is a schematic cross-sectional structural view of a solder resist pattern in which a portion other than the connection pad 3 to be soldered on the circuit board is covered with the resin composition layer 4. The structure shown in FIG. 1 is called an SMD (Solder Masked Defined) structure, and is characterized in that the opening of the resin composition layer 4 is smaller than that of the connection pad 3. The structure shown in FIG. 2 is called an NSMD (Non Solder Masked Defined) structure, and is characterized in that the opening of the resin composition layer 4 is larger than that of the connecting pad 3.

The opening of the resin composition layer 4 in FIG. 1 is formed by removing a part of the resin composition layer. As a processing method for removing the resin composition layer containing the resin composition containing the inorganic filler and the alkali-insoluble resin, a known method such as a drill, a laser, a plasma, or a blast can be used. Moreover, these methods can be combined as needed. Among them, processing with a laser such as a carbon dioxide gas laser, an excimer laser, a UV laser, or a YAG laser is the most common, and a part of the resin composition layer 4 is removed by laser light irradiation to form a through hole for forming a through hole. , Through holes and non-through holes such as an opening for forming a via hole and an opening for forming a connection pad 3 can be formed (see, for example, Patent Documents 1 and 2).

However, in the processing by irradiation with laser light, for example, when a carbon dioxide laser is used, a large number of shots are required, and as a post-treatment, a desmear treatment is performed using an oxidizing agent consisting of an aqueous solution such as chromic acid or permanganate. Need to be done. Further, when an excimer laser is used, the processing time becomes very long. Furthermore, the UV-YAG laser has an advantage over other laser beams in that it can perform microfabrication, but it removes not only the resin composition layer but also the metal layer existing in the vicinity at the same time. There was a problem.

Further, when the resin composition layer is irradiated with laser light, light energy is absorbed by the object at the irradiated portion, and the object generates heat excessively according to the specific heat, and the heat generation causes melting, deformation, alteration, and discoloration of the resin. In some cases, such defects may occur. Further, it has been proposed to use a thermosetting resin in the resin composition layer in response to this heat generation, but when the thermosetting resin is used, cracks may easily occur in the resin composition layer. ..

As a method other than laser light irradiation, a method of removing the resin composition layer by a wet blast method can be mentioned. A resin composition layer is formed on a circuit board having a connection pad on an insulating substrate, then cured, and a resin layer for forming a wet blasting mask is provided on the resin composition layer. By exposing and developing, a patterned wet blasting mask is formed. Then, the resin composition layer is removed by performing wet blasting to form an opening, and subsequently, the mask for wet blasting is removed (see, for example, Patent Document 3).

However, in the processing by wet blasting, the thickness that can be polished by one blasting treatment is small, and it is necessary to repeat the blasting treatment a plurality of times. Therefore, not only the time required for polishing becomes very long, but also the portion to which the resin composition layer is adhered is uniform depending on the material, such as on the connection pad or on the insulating substrate. It was extremely difficult to perform high-precision processing because it was not possible to perform proper polishing and residue was generated.

As a processing method for removing a resin composition layer containing a resin composition containing an inorganic filler and an alkali-insoluble resin, an etching method performed by an immersion treatment using a hydrazine-based chemical solution at 40 ° C. as an etching solution is disclosed. (See, for example, Patent Document 4). However, hydrazine is a toxic substance, which is not preferable because it has a large effect on the human body and has a large environmental load.

Further, an etching method using an etching solution containing 15 to 45% by mass of an alkali metal hydroxide is disclosed (see, for example, Patent Document 5). In Patent Document 5, as a more preferable embodiment, an etching solution further containing an ethanolamine compound is also disclosed. When a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler and 30 to 50% by mass of an inorganic filler is etched using the etching solution of Patent Document 5, the surface after etching is organically filled. The residue of the agent may be left.

Further, when the resin composition layer is etched with reference to the etching method disclosed in Patent Document 5, the opening in the resin composition layer is opened due to insufficient affinity between the etching solution and the resin composition layer. In the small-diameter opening treatment such that the diameter is Φ100 μm or less, unetched portions may be generated. Therefore, there has been a demand for an etching method in which unetched portions are not generated.

Japanese Unexamined Patent Publication No. 2003-101244 International Publication No. 2017/38713 Pamphlet Japanese Unexamined Patent Publication No. 2008-300691 International Publication No. 2018/88345 Pamphlet International Publication No. 2018/186362 Pamphlet

An object of the present invention is to provide a novel etching solution suitable for a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler.
Efficiently removes the resin composition (resin composition layer containing the resin composition) in the process of removing the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler using an etching solution. Another object of the present invention is to provide an etching solution and an etching method for a resin composition that can be stably removed (for example, without residue and has high in-plane uniformity). Further, another object of the present invention is to provide an etching method capable of suppressing the occurrence of unetched portions even in a small-diameter opening treatment in which the opening diameter is Φ100 μm or less.

The present inventors have found that the above problems can be solved by the following means and the like.

<1>
Etching solution of a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler and 30 to 50% by mass of an inorganic filler [etching solution for a resin composition, etching solution for a resin composition, resin In the etching solution for etching the composition layer (layer formed of the resin composition)], the etching solution is used as a first component of 15 to 45% by mass of alkali metal hydroxide and a second component. An etching solution containing 1 to 40% by mass of an ethanolamine compound and containing at least one third component selected from an alcohol compound and a carboxylic acid compound.

<2>
The etching solution according to <1>, wherein the third component contains at least one selected from a polyol compound, a polyvalent carboxylic acid compound, and a hydroxy acid compound.

<3>
The etching solution according to <1> or <2>, wherein the third component contains 3 to 60% by mass of a polyol compound.

<4>
The etching solution according to <2> or <3>, wherein the polyol compound has a molecular weight of 80 or more and 200 or less.

<5>
The etching solution according to any one of <2> to <4>, wherein the polyol compound has three or more hydroxyl groups.

<6>
The etching solution according to any one of <2> to <5>, wherein the polyol compound contains glycerin.

<7>
The etching solution according to any one of <1> to <6>, wherein the third component contains 2 to 20% by mass of a polyvalent carboxylic acid compound.

<8>
The etching solution according to any one of <1> to <7>, wherein the third component contains 2 to 20% by mass of a hydroxy acid compound.

<9>
The etching solution according to any one of <1> to <8>, wherein the etching solution contains 0.1 to 3% by mass of an aromatic alcohol compound.

<10>
Using the etching solution according to any one of <1> to <9>, an etching treatment is performed on a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler, and 30 to 50% by mass of an inorganic filler. A method for etching a resin composition, which comprises a step of etching a resin composition.

<11>
Using the etching solution according to any one of <1> to <9>, an etching treatment is performed on a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler, and 30 to 50% by mass of an inorganic filler. A method for etching a resin composition, which comprises an etching step for etching and an ultrasonic irradiation step for irradiating ultrasonic waves after the etching step.

<12>
The resin composition according to <10> or <11>, further comprising a step of pretreating with a pretreatment liquid consisting of an acidic aqueous solution containing 2.5 to 7.5% by mass of anionic surfactant before the etching step. Etching method of things.

<13>
The method for etching a resin composition according to any one of <10> to <12>, which has a washing step after the etching step and the time from the end of the etching step to the start of the washing step is within 30 seconds.

<14>
The method for etching a resin composition according to any one of <10> to <13>, wherein an etching resist is used in the etching step, and the etching resist is a metal mask or a dry film resist.

According to the present invention, it is possible to provide a novel etching solution suitable for a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler.
Further, according to the present invention, in a process of removing an alkali-insoluble resin, an organic filler and a resin composition containing an inorganic filler using an etching solution, the resin composition (a resin containing the resin composition) is used. It is possible to provide an etching solution and an etching method for a resin composition, which can efficiently remove (for example, stably remove the composition layer) without any residue and have high in-plane uniformity. Further, according to the present invention, it is possible to provide an etching method capable of suppressing the occurrence of unetched portions even in a small-diameter opening process in which the opening diameter is Φ100 μm or less.

It is a schematic cross-sectional structure diagram of a solder resist pattern. It is a schematic cross-sectional structure diagram of a solder resist pattern. It is sectional drawing which showed an example of the step of etching the resin composition layer 4 by the etching method of this invention.

Hereinafter, embodiments for carrying out the present invention will be described. In the present specification, the "etching liquid of the resin composition" may be abbreviated as "etching liquid", and the "etching method of the resin composition" may be abbreviated as "etching method".

The etching solution of the present invention is, for example, a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler (particularly, an alkali-insoluble resin, 20 to 40% by mass of an organic filler and 30 to 50% by mass of an inorganic filler. It is used in the process of removing the resin composition containing the agent. Further, in the etching method of the present invention, a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler (particularly, an alkali-insoluble resin, 20 to 40% by mass of an organic filler) using the etching solution of the present invention. It is characterized by having an etching step of etching (a resin composition containing 30 to 50% by mass of an inorganic filler).

<Etching liquid>
The etching solution of the present invention contains a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler (particularly, an alkali-insoluble resin, 20 to 40% by mass of an organic filler, and 30 to 50% by mass of an inorganic filler. It is an etching solution (an etching solution for a resin composition, a solution for etching a resin composition) of a resin composition containing the resin composition.

The etching solution of the present invention usually contains an alkali metal hydroxide as a first component (particularly, an alkali metal hydroxide of 15 to 45% by mass). Since the alkali-insoluble resin has the property of not being dissolved in the alkaline aqueous solution, it cannot be originally removed by the alkaline aqueous solution. However, the resin composition containing the alkali-insoluble resin can be removed by using the etching solution of the present invention. This is because the inorganic filler in the highly filled resin composition, that is, the inorganic filler filled in the resin composition with a high content of 30 to 50% by mass, has a high concentration of alkali metal hydroxide. This is because it is dissolved, dispersed and removed by an etching solution containing. Further, when the alkali-insoluble resin and the organic filler filled with a high content of 20 to 40% by mass are swollen by the etching solution, a difference in expansion ratio between the alkali-insoluble resin and the organic filler is generated. It is presumed that this is because the structure of the resin composition becomes brittle and the progress of etching is promoted.

When the content of alkali metal hydroxide (ratio to the whole etching solution, hereinafter the same in the same expression) is 15% by mass or more, the solubility of the inorganic filler is excellent and the content of alkali metal hydroxide is high. When it is 45% by mass or less, the alkali metal hydroxide is unlikely to precipitate, so that the stability of the liquid with time is excellent. The content of the alkali metal hydroxide is more preferably 20 to 45% by mass.

As the alkali metal hydroxide, at least one compound selected from the group of potassium hydroxide, sodium hydroxide and lithium hydroxide is preferably used. As the alkali metal hydroxide, one of these may be used alone, or two or more of them may be used in combination.

The etching solution of the present invention usually contains an alkanolamine compound (usually an ethanolamine compound, particularly 1 to 40% by mass of an ethanolamine compound) as a second component. When the etching solution contains an ethanolamine compound or the like, the ethanolamine compound or the like permeates into the resin composition, the resin composition is swollen, and the inorganic filler can be uniformly dissolved. When the content of the alkanolamine compound (for example, ethanolamine compound) is 1% by mass or more, the swelling property of the alkali-insoluble resin is excellent, and when it is 40% by mass or less, the compatibility with water is high and phase separation is performed. It is less likely to occur and has excellent stability over time. The content of the alkanolamine compound (for example, ethanolamine compound) is more preferably 3 to 35% by mass.

The alkanolamine compound (for example, an ethanolamine compound) may be of any kind such as a primary amine, a secondary amine, or a tertiary amine, and one kind may be used alone, or two or more kinds may be used. May be used in combination. As an example of a typical amine compound, 2-aminoethanol which is a primary amine; a mixture of a primary amine and a secondary amine (that is, a primary amino group and a secondary amino in one molecule) 2- (2-Aminoethylamino) ethanol which is a compound having a group); 2- (methylamino) ethanol or 2- (ethylamino) ethanol which is a secondary amine; 2,2 which is a tertiary amine ′ -Methyliminodiethanol, 2- (dimethylamino) ethanol and the like can be mentioned. Of these, 2- (methylamino) ethanol and 2- (2-aminoethylamino) ethanol are more preferable.

The etching solution of the present invention contains at least one third component selected from an alcohol compound and a carboxylic acid compound. In particular, the etching solution of the present invention may contain 3 to 60% by mass of a polyol compound, 2 to 20% by mass of a polyvalent carboxylic acid compound, or 2 to 20% by mass of a hydroxy acid compound as a third component. .. By containing such a third component (for example, a polyol compound, a polyvalent carboxylic acid compound and / or a hydroxy acid compound), the etching solution of the present invention contains an alkali-insoluble resin, an organic filler and a dissolved inorganic filler. Can be dispersed and removed at the same time.

Although the mechanism of this effect is beyond speculation, it is considered to be related to the above-mentioned dissolution / dispersion removal mechanism of the etching solution of the present invention. In order to stably etch and remove the resin composition, a part or all of the highly filled inorganic filler in the resin composition is dissolved in an etching solution containing a high concentration of alkali metal hydroxide. It is necessary to remove the alkali-insoluble resin, the organic filler and the dissolved inorganic filler at the same time when the film shape as the resin composition cannot be maintained. If the removal of only one of them proceeds, the remaining components become residues and remain on the surface after etching. Since the etching solution contains a third component (for example, a polyol compound, a polyvalent carboxylic acid compound and / or a hydroxy acid compound), it has a function of collecting components whose film shape cannot be maintained, and at the same time improves the performance of removing them. It is thought that it is causing. It is considered that the effect increases the margin of the treatment time in which no residue remains, and the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler can be stably removed.

The content of the third component (the total content thereof when two or more are combined) depends on the components constituting the third component, but is, for example, 0.1% by mass or more, 0.5% by mass or more, preferably 0.5% by mass or more. It may be 1% by mass or more, more preferably 1.5% by mass or more, particularly 2% by mass or more.
The content of the third component depends on the components constituting the third component, but is, for example, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, and the like. There may be.

[Alcohol compound]
Examples of the alcohol compound [alcohol compound that is not an alkanolamine compound (ethanolamine compound)] include monoalcohol compounds [for example, alkanol (for example, ethanol, propanol, butanol, pentanol, hexanol, etc.), and alicyclic monool (for example,). Non-aromatic monool compounds such as cyclohexanol) (aliphatic monool) and the like], polyol compounds and the like are included.
One type of alcohol compound may be used alone, or two or more types may be used in combination.

The alcohol compound may preferably contain a polyol compound.

Further, the alcohol compound may be an aromatic alcohol compound [an aromatic alcohol compound described later (for example, benzyl alcohol, phenoxyethanol, etc.)], and a non-aromatic alcohol compound (non-aromatic monool compound, non-aromatic). It may be a polyol compound) or may contain both of them.
The non-aromatic alcohol compound may be either a saturated compound or an unsaturated compound.

Typically, the alcohol compound often contains at least a non-aromatic alcohol compound (particularly a non-aromatic polyol compound). On the other hand, as described later, the aromatic alcohol compound may be preferably combined with the third component (further, the first component and the second component).

When the third component contains an alcohol compound, the content of the alcohol compound depends on the total content of the third component and the like, but is, for example, 0.1% by mass or more, 0.5% by mass or more, preferably 1. It may be mass% or more, more preferably 2 mass% or more, and particularly 3 mass% or more. The content of the alcohol compound may be, for example, 60% by mass or less, 50% by mass or less, 40% by mass or less, and the like.

When the third component is composed of an alcohol compound, if the content of the alcohol compound (for example, polyol compound) used in the etching solution of the present invention is small (for example, less than 3% by mass), the ability to disperse all together. Is insufficient, and if it is too much (for example, more than 60% by mass), it may be too cohesive and the removability may be insufficient. Therefore, the content of the alcohol compound (for example, the polyol compound) depends on the total content of the third component and the like, but is preferably selected within a range in which removability can be efficiently realized, and more preferably 10 to 40 mass. %.

The polyol compound used in the etching solution of the present invention has a preferable molecular weight range, preferably 80 or more and 200 or less. Further, as the polyol compound, a compound having three or more hydroxyl groups is preferable.

Further, preferred polyol compounds include compounds in which hydroxyl groups are relatively densely present. In such a polyol compound, the molecular weight per hydroxy group may be, for example, 100 or less, 80 or less, 60 or less, 50 or less, 40 or less, 35 or less, and the like.

The polyol compound may be either an aliphatic polyol compound or an aromatic polyol compound, but it is particularly preferable to use at least an aliphatic polyol compound (alkane polyol or the like). The polyol compound may be sugar or sugar alcohol.

As a specific example, a polyol having three or more hydroxyl groups [for example, alcantriol (for example, C _3-10 alcantriol such as glycerin and trimethylolpropane), alcantetraol (for example, erythritol, pentaerythritol and the like), etc. C _4-12 Alcantetraol), Alcan polyols having 5 or more hydroxyl groups (eg, sorbitol, xylitol, boremitol, etc.), and multimers of polyols having 3 or more hydroxyl groups (eg, diglycerin, dipenta) Ellis Ritol), etc.], diols [eg, poly (alcandiol) [eg, poly C _2-6 alcandiol such as diethylene glycol, dipropylene glycol], alcandiol (eg, ethylene glycol, propylene glycol, butanediol, etc. C _{2) -10} alcandiol), etc.]. Of these, glycerin is particularly preferable. Further, as the polyol compound, one type may be used alone, or two or more types may be used in combination.

[Carboxylic acid compound]
Carboxylic acid compounds (sometimes simply referred to as "carboxylic acids") include carboxylic acids, carboxylic acid derivatives (eg, carboxylic acid salts) and the like. The carboxylic acid compound (carboxylic acid, carboxylic acid salt, etc.) may be a hydrate or the like.

Examples of the carboxylic acid include monocarboxylic acid (monovalent carboxylic acid), polyvalent carboxylic acid (polyvalent carboxylic acid described later), hydroxy acid (hydroxy acid described later) and the like.

Examples of the monocarboxylic acid include fatty acids [for example, alkane acids such as formic acid, acetic acid and propionic acid (for example, C _1-10 alkane acids)] and the like.

The carboxylic acid may be an amino acid (aminocarboxylic acid).

The salt is not particularly limited, and is, for example, a metal salt [for example, an alkali metal salt (for example, lithium salt, sodium salt, potassium salt, etc.), an alkaline earth metal salt (for example, magnesium salt, calcium salt, etc.), zinc. Salts, etc.], amine salts, ammonium salts, etc. may be mentioned.

One type of carboxylic acid compound may be used alone, or two or more types may be used in combination.

Preferred carboxylic acid compounds include polyvalent carboxylic acid compounds and hydroxy acid compounds. Therefore, the carboxylic acid compound may contain at least one selected from a polyvalent carboxylic acid compound and a hydroxy acid compound.

When the third component contains a carboxylic acid compound, the content of the carboxylic acid compound depends on the total content of the third component and the like, but is preferably 0.1% by mass or more and 0.5% by mass or more, for example. May be 1% by mass or more, more preferably 1.5% by mass or more, and particularly 2% by mass or more. The content of the carboxylic acid compound may be, for example, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, and the like.

(Polyvalent carboxylic acid compound)
When the third component is composed of a polyvalent carboxylic acid compound, if the content of the polyvalent carboxylic acid compound used in the etching solution of the present invention is small (for example, less than 2% by mass), the ability to disperse all together. Is insufficient, and if it is too large (for example, exceeding 20% by mass), it may be too cohesive and the removability may be insufficient. Therefore, the content of the polyvalent carboxylic acid compound depends on the total content of the third component and the like, but is preferably selected within a range in which removability can be efficiently realized, and more preferably 3 to 15% by mass. .. As described above, the polyvalent carboxylic acid (polyvalent carboxylic acid compound) used in the etching solution of the present invention also includes derivatives (for example, salts, etc.) and hydrates of the polyvalent carboxylic acid.

The polyvalent carboxylic acid may be either an aliphatic polyvalent carboxylic acid or an aromatic polyvalent carboxylic acid, and typically, an aliphatic polyvalent carboxylic acid may be preferably used. Such an aliphatic polyvalent carboxylic acid may be either a saturated fatty acid or an unsaturated fatty acid.

In the polyvalent carboxylic acid, the number of carboxyl groups may be 2 or more, and may be, for example, 2 to 10 (for example, 2 to 6).

Preferred polyvalent carboxylic acids include compounds in which carboxyl groups are relatively densely present. In such a polyvalent carboxylic acid, the molecular weight per carboxyl group may be, for example, 100 or less, 80 or less, 60 or less, 50 or less, 40 or less, 35 or less, and the like.

Examples of the polyvalent carboxylic acid (polyvalent carboxylic acid compound) used in the etching solution of the present invention include C _2-12 alkanes such as oxalic acid, malonic acid, succinic acid, and glutaric acid. Diacid), alkenepolycarboxylic acid (eg, C _4-12 alkenedicarboxylic acid such as maleic acid, fumaric acid), carboxyalkylamine [eg, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), L-asparagin Acid-N, N-2 acetic acid (ADSA), diethylenetriamine-5 acetic acid (DTPA)] and derivatives thereof (salts, etc.) are exemplified. Among these polyvalent carboxylic acids (polyvalent carboxylic acid compounds), malonic acid, maleic acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriamine-5acetic acid (DTPA) and salts thereof are alkali-insoluble resins, organic fillers and inorganic fillers. In the process of removing the resin composition containing the agent, it is more preferable to stably remove the resin composition layer containing the resin composition without any residue, and malonic acid and ethylenediaminetetraacetic acid (EDTA) and these are preferable. Salts are more preferable, and ethylenediaminetetraacetic acid (EDTA) and salts thereof are particularly preferable. Further, as the polyvalent carboxylic acid (polyvalent carboxylic acid compound), one type may be used alone, or two or more types may be used in combination.

(Hydroxy acid compound)
When the third component is composed of a hydroxy acid compound, if the content of the hydroxy acid compound used in the etching solution of the present invention is small (for example, less than 2% by mass), the ability to disperse all together is insufficient. If it is too much (for example, more than 20% by mass), it may be too cohesive and the removability may be insufficient. Therefore, the content of the hydroxy acid compound depends on the total content of the third component and the like, but is preferably selected within a range in which removability can be efficiently realized, and more preferably 3 to 15% by mass. As described above, the hydroxy acid (hydroxy acid compound) used in the etching solution of the present invention also includes a derivative of the hydroxy acid (for example, a salt or the like). Further, as described above, the hydroxy acid, its salt and the like may be hydrates.

The hydroxy acid may be either an aliphatic hydroxy acid or an aromatic hydroxy acid, and the aliphatic hydroxy acid may be either a saturated fatty acid or an unsaturated fatty acid.

In the hydroxy acid, the number of hydroxyl groups may be 1 or more, and may be, for example, 1 to 10 (for example, 1 to 5).
In the hydroxy acid, the number of carboxyl groups may be 1 or more, and may be, for example, 1 to 10 (for example, 1 to 5).

Preferred hydroxy acids include compounds in which hydroxy and carboxy groups are relatively densely present. In such a hydroxy acid, the molecular weight per total amount of hydroxyl groups and carboxyl groups may be, for example, 100 or less, 80 or less, 60 or less, 50 or less, 40 or less, 35 or less, and the like.

Examples of the hydroxy acid (hydroxy acid compound) used in the etching solution of the present invention include aliphatic hydroxy acids [for example, hydroxyalcancarboxylic acids (eg, glycolic acid, lactic acid, tarthronic acid, glyceric acid, leucic acid, malic acid, etc.). Tartrate acid, gluconic acid, citric acid, isocitrate, mevalonic acid, pantoic acid, hydroxypentanoic acid, hydroxyhexanoic acid, etc.), hydroxyalkyl-carboxyalkylamine (eg, hydroxyethyliminodiacetic acid, hydroxyiminodichuccinic acid, etc.), Alicyclic hydroxy acids (eg, quinic acids)], aromatic hydroxy acids [eg, salicylic acids, 4-hydroxyphthalic acids, 4-hydroxyisophthalic acids, cleosortic acids (homosalicylic acids, hydroxy (methyl) benzoic acids), Vanillic acid, syring acid, resorcylic acid, protocatechuic acid, gentidic acid, orseric acid, gallic acid, mandelic acid, atrolactic acid, melilotoic acid, floretic acid, kumalic acid, umberic acid, coffee acid, etc.], and derivatives thereof ( For example, salt, etc.). Among these hydroxy acids (hydroxy acid compounds), malic acid, tartaric acid, gallic acid, 4-hydroxyisophthalic acid and salts thereof are used in the process of removing a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler. , The resin composition layer containing the resin composition is more preferable because it can be stably removed without residue, tartaric acid and 4-hydroxyphthalic acid and salts thereof are more preferable, and tartaric acid and salts thereof are particularly preferable. Further, as the hydroxy acid, one type may be used alone, or two or more types may be used in combination.

(Aromatic alcohol compound)
The etching solution may contain an aromatic alcohol compound. The aromatic alcohol compound corresponds to the alcohol compound (that is, the third component), but in particular, another third component [for example, a non-aromatic alcohol compound (polyol compound or the like), a carboxylic acid compound (multivalent). Carboxylic acid compounds, hydroxy acid compounds, etc.)] are preferably used in combination (used as the fourth component).

Specifically, the etching solution of the present invention preferably contains an aromatic alcohol compound (for example, 0.1 to 3% by mass of an aromatic alcohol compound) as a fourth component. Since the etching solution of the present invention contains an aromatic alcohol compound, the effect of simultaneously dispersing and removing the alkali-insoluble resin, the organic filler and the dissolved inorganic filler is enhanced. Therefore, in the <etching method> described later, the resin composition layer can be removed without any residue without performing the ultrasonic irradiation step. Of course, the etching method of the present invention having an ultrasonic irradiation step may be performed using an etching solution containing an aromatic alcohol as a fourth component.

Although the mechanism of this effect is beyond speculation, it is considered to be related to the above-mentioned dissolution / dispersion removal mechanism of the etching solution of the present invention. In order to stably etch and remove the resin composition, a part or all of the highly filled inorganic filler in the resin composition is dissolved in an etching solution containing a high concentration of alkali metal hydroxide. It is necessary to remove the alkali-insoluble resin, the organic filler and the dissolved inorganic filler at the same time when the film shape as the resin composition cannot be maintained. If the removal of only one of them proceeds, the remaining components become residues and remain on the surface after etching. Since the etching solution contains another third component (for example, a polyol compound, a polyvalent carboxylic acid compound and / or a hydroxy acid compound, etc.), it has a function of collecting components that cannot maintain the film shape and simultaneously removes the components. It is thought that the performance is improved. It is considered that the etching solution further contains an aromatic alcohol compound to improve the performance of removing the undissolved alkali-insoluble resin and the organic filler. It is considered that the effect increases the margin of the treatment time in which no residue remains, and the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler can be stably removed.

When an aromatic alcohol compound is used, the content of the aromatic alcohol compound depends on the total content of the third component and the like, but is, for example, 0.1% by mass or more, 0.5% by mass or more, and the like. It may be 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, and the like.
When the content of the aromatic alcohol compound used in the etching solution of the present invention is, for example, about 0.1% by mass or more, the performance of removing the alkali-insoluble resin and the organic filler is excellent, and about less than about 3% by mass. If it is, the compatibility with water becomes high, phase separation is less likely to occur, and the stability over time and the treatment uniformity are excellent. The content of the aromatic alcohol compound is more preferably 0.5 to 2.5% by mass.

Examples of the aromatic alcohol compound used in the etching solution of the present invention include aralkyl alcohol (for example, benzyl alcohol, 4-methylbenzyl alcohol, 3-methylbenzyl alcohol, 2-methylbenzyl alcohol, 2-phenylethanol, 3 -Phenylpropanol, 1-phenyl-1-propanol, 1-phenyl-2-propanol, 4-phenyl-1-butanol, 4-phenyl-2-butanol, 1-phenyl-2-butanol, 2-phenyl-2- Butanol, etc.), (Poly) Alcandiol monoaryl ether (eg, 2-phenoxyethanol, phenyldiglycol, phenylpropylene glycol, phenyldipropylene glycol, etc.), (Poly) Alcandiol monoaralkyl ether (eg, benzyl glycol, benzyldi, etc.) Glycol, etc.) are exemplified. Among these aromatic alcohols, in the process of removing the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler, the resin composition layer containing the resin composition is stably produced without any residue. For removal, benzyl alcohol and 2-phenoxyethanol are more preferred, especially 2-phenoxyethanol. Further, the aromatic alcohol may be used alone or in combination of two or more.

A coupling agent, a leveling agent, a colorant, a surfactant, an antifoaming agent, an organic solvent and the like can be appropriately added to the etching solution of the present invention, if necessary. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone and cyclohexanone; acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate; carbitols such as cellosolve and butyl carbitol; Aromatic hydrocarbons such as toluene and xylene; amide-based solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone can be mentioned.

The etching solution of the present invention is preferably an alkaline aqueous solution. As the water used in the etching solution of the present invention, tap water, industrial water, pure water and the like can be used. Of these, it is preferable to use pure water. In the present invention, pure water generally used for industrial purposes can be used.
<Pretreatment liquid>
The pretreatment liquid according to the present invention is, for example, an acidic aqueous solution containing 2.5 to 7.5% by mass of an anionic surfactant. Examples of the anionic surfactant contained in the pretreatment liquid according to the present invention include lauryl sulfate, polyoxyethylene alkyl ether sulfate, polyoxyalkylene alkenyl ether sulfate, alkylbenzene sulfonate, dodecylbenzene sulfonate, and alkyl. Examples thereof include naphthalene sulfonate, dialkyl sulfosuccinate, alkyldiphenyl ether disulfonate, alkane sulfonate, alkenyl succinate and the like. Among these anionic surfactants, polyoxyethylene alkyl ether sulfate and alkylnaphthalene sulfonate are unetched even in a small-diameter opening treatment such that the opening diameter of the opening in the resin composition layer is Φ100 μm or less. Is preferable, and alkylnaphthalene sulfonate is particularly preferable. As the counterion, alkali metal ions and alkanolamine salt ions are preferable. Further, these anionic surfactants may be used alone or in combination of two or more.

In order to suppress the occurrence of unetched portions even in a small-diameter opening treatment in which the opening diameter of the opening in the resin composition layer is Φ100 μm or less, the content of the anionic surfactant contained in the pretreatment liquid is set. It is preferably 2.5% by mass or more, and more preferably 3% by mass or more. In addition, the obtained effect is not increased, which is uneconomical, it takes time to wash with water after the pretreatment, and when the washing with water is insufficient, the aggregation of the anionic surfactant leads to the generation of unetched parts. From the viewpoint of risk, it is preferably 7.5% by mass or less, and more preferably 6% by mass or less.

The pretreatment liquid according to the present invention is acidic, and the pH is 6 or less from the viewpoint of suppressing the occurrence of unetched portions even in a small-diameter opening treatment in which the opening diameter of the opening in the resin composition layer is Φ100 μm or less. It is preferable to have. Further, the pH is preferably 1 or more from the viewpoint that the obtained effect is not increased, it is uneconomical, and it takes time to mix the pH adjuster. As the pH adjuster, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, hydroxide salts, carbonates and the like can be used. Further, the pretreatment liquid according to the present invention may contain known additives such as an antifoaming agent, an antifoaming agent, a thickener and a preservative.

As the water used for the pretreatment liquid according to the present invention, tap water, industrial water, pure water and the like can be used. Of these, it is preferable to use pure water. In the present invention, pure water generally used for industrial purposes can be used.

<Resin composition>
The resin composition according to the present invention is a resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler. The content of the organic filler in the resin composition is, for example, 20 to 40% by mass with respect to 100% by mass of the non-volatile content in the resin composition. When the content of the organic filler is less than 20% by mass, the influence of the difference in expansion rate generated by the etching solution containing the alkali metal hydroxide on the entire resin composition becomes small, and the etching does not proceed. If the content of the organic filler exceeds 40% by mass, the flexibility of the resin composition tends to decrease due to the decrease in fluidity, which may be inferior in practicality.

The content of the inorganic filler is, for example, 30 to 50% by mass with respect to 100% by mass of the non-volatile content in the resin composition. When the content of the inorganic filler is less than 30% by mass, the amount of the inorganic filler as a site dissolved by the etching solution containing the alkali metal hydroxide is too small with respect to the entire resin composition, so that the etching proceeds. It may not be. If the content of the inorganic filler exceeds 50% by mass, the flexibility of the resin composition tends to decrease due to the decrease in fluidity, which may be inferior in practicality.

In the present invention, examples of the organic filler include polytetrafluoroethylene (PTFE), fluoroethylene-propylene copolymer (FEP), perfluoroalkoxypolymer (PFA), chlorotrifluoroethylene (CTFE), and tetra. At least one fluororesin selected from the group consisting of fluoroethylene-chlorotrifluoroethylene copolymer (TFE / CTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and polychlorotrifluoroethylene (PCTFE). Can be mentioned. One of these resins may be used alone, or two or more of these resins may be used in combination. PTFE is preferable from the viewpoint of reducing the dielectric constant of the resin composition layer.

In the present invention, examples of the inorganic filler include silicates such as silica, glass, clay and mica; oxides such as alumina, magnesium oxide, titanium oxide and silica; carbonates such as magnesium carbonate and calcium carbonate; water. Hydroxides such as aluminum oxide, magnesium hydroxide and calcium hydroxide; sulfates such as barium sulfate and calcium sulfate can be mentioned. Further, examples of the inorganic filler include aluminum borate, aluminum nitride, boron nitride, strontium titanate, barium titanate and the like. Among these, at least one compound selected from the group consisting of silica, glass, clay and aluminum hydroxide is more preferably used because it dissolves in an aqueous solution containing an alkali metal hydroxide. Silica is more preferable because it has excellent low thermal expansion property, and spherical fused silica is particularly preferable. As the inorganic filler, one of these may be used alone, or two or more of them may be used in combination.

The alkali-insoluble resin in the present invention will be described. The alkali-insoluble resin is not particularly limited except that it is insoluble in an aqueous alkaline solution. Specifically, it is a resin having a very small content of a carboxyl group-containing resin or the like required to dissolve in an alkaline aqueous solution, and has an acid value (JIS K2501) that is an index of the content of free carboxyl groups in the resin. : 2003) is preferably less than 40 mgKOH / g. More specifically, the alkali-insoluble resin is, for example, a resin containing an epoxy resin and a thermosetting agent that cures the epoxy resin. Examples of the alkaline aqueous solution include alkali metal silicate, alkali metal hydroxide, alkali metal phosphate, alkali metal carbonate, ammonium phosphate, aqueous solution containing an inorganic alkaline compound such as ammonium carbonate, monoethanolamine, and the like. Diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, trimethyl-2-hydroxyethylammonium hydroxide (choline), etc. An aqueous solution containing the organic alkaline compound of the above can be mentioned.

Examples of the epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin. Can be mentioned. Further, examples of the epoxy resin include biphenyl type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, phenoxy type epoxy resin, fluorene type epoxy resin and the like. As the epoxy resin, one of these may be used alone, or two or more of them may be used in combination.

The thermosetting agent is not particularly limited as long as it has a function of curing the epoxy resin, but preferred ones include a phenol-based curing agent, a naphthol-based curing agent, an active ester-based curing agent, and a benzoxazine-based curing agent. Examples thereof include cyanate ester resin. As the thermosetting agent, one of these may be used alone, or two or more thereof may be used in combination.

In addition to the above thermosetting agent, a curing accelerator can be further contained. Examples of the curing accelerator include an organic phosphine compound, an organic phosphonium salt compound, an imidazole compound, an amine adduct compound, a tertiary amine compound and the like. As the curing accelerator, one of these may be used alone, or two or more thereof may be used in combination. When a cyanate ester resin is used as a thermosetting agent, an organometallic compound used as a curing catalyst may be added for the purpose of shortening the curing time. Examples of the organometallic compound include an organocopper compound, an organozinc compound, and an organocobalt compound.

A resin composition containing an alkali-insoluble resin, an organic filler and an inorganic filler can form an insulating resin composition layer by thermosetting, but etching using the etching solution of the present invention is usually performed. It proceeds in the state of A stage (before the start of the curing reaction) or B stage (intermediate stage of the curing reaction). In the A stage or B stage, the alkali-insoluble resin is not dissolved in the etching solution of the present invention, but the inorganic filler is partially or completely dissolved by the etching solution of the present invention, and the alkali-insoluble resin for the etching solution is used. Dispersion removal of the resin composition proceeds due to the difference in the expansion rate of the organic filler. When the C stage is reached and the resin is completely cured, it becomes difficult for the etching solution of the present invention to swell the resin composition layer and penetrate into the resin composition layer, which makes uniform etching difficult. There is.

The thermosetting conditions from the A stage to the B stage are preferably 100 to 160 ° C. for 10 to 60 minutes, and more preferably 100 to 130 ° C. for 10 to 60 minutes, but are limited thereto. It's not a thing. When heated at a high temperature exceeding 160 ° C., thermosetting further progresses, and the etching process using the etching solution of the present invention may become difficult.

<Etching method>
The etching method of the present invention will be described below. FIG. 3 is a cross-sectional process diagram showing an example of a step of etching the resin composition layer 4 by the etching method of the present invention. In this etching method, a solder resist pattern in which a part or all of the solder connection pad 3 on the circuit board is exposed from the resin composition layer 4 can be formed.

In the step (I), a conductor pattern is formed by patterning the copper foil 3'on the surface of the copper-clad laminate 1'consisting of the insulating layer 2 and the copper foil 3', and the circuit board has the solder connection pad 3. Form 1.

In the step (II), the resin composition layer 4 with the copper foil 6 is formed on the surface of the circuit board 1 so as to cover the entire surface.

In the step (III), the copper foil 6 on the resin composition layer 4 is patterned to form the metal mask 5 as the etching resist 5. The copper foil 3'and the copper foil 6 can be patterned by, for example, a copper etching treatment using a ferric chloride solution, a cupric chloride solution, or the like.

After the step (III), in the step (IV), in the etching step, the resin composition layer is exposed through the etching resist 5 until a part or all of the solder connection pad 3 is exposed by the etching solution of the resin composition layer. 4 is etched.

After the step (III), in the step (IV), the affinity between the etching solution and the resin composition layer 4 is improved by the pretreatment step of bringing the pretreatment liquid into contact with the resin composition layer 4 and the etching resist 5. After that, in the etching step, the resin composition layer 4 can be etched with the etching solution for the resin composition layer through the etching resist 5 until a part or all of the solder connection pad 3 is exposed.

In step (IV) -2, the resin residue 8 is removed in the washing step following the etching process.

In step (IV) -2, the resin residue 8 can also be removed by irradiating ultrasonic waves in the washing step following the etching step.

In the step (V), the etching resist 5 (metal mask) is removed by etching to form a solder resist pattern in which a part or all of the solder connection pad 3 is exposed from the resin composition layer 4.

In the present invention, the pretreatment time is not particularly limited, but even in a small-diameter opening treatment in which the opening diameter of the opening in the resin composition layer is Φ100 μm or less, it is 1 minute or more in order to suppress the occurrence of unetched portions. It is preferably present, and more preferably 3 minutes or more. The pretreatment time is preferably 10 minutes or less. The temperature of the pretreatment liquid according to the present invention is not particularly limited, but even in a small-diameter opening treatment in which the opening diameter of the opening in the resin composition layer is Φ100 μm or less, in order to suppress the occurrence of unetched portions, the temperature is 10 ° C. The above is preferable, and the temperature is more preferably 30 ° C. or higher. The temperature of the pretreatment liquid is preferably 70 ° C. or lower.

In the etching method of the present invention, the temperature of the etching solution is preferably 60 to 90 ° C. The optimum temperature varies depending on the type of resin composition, the thickness of the resin composition layer containing the resin composition, the shape of the pattern obtained by the process of removing the resin composition, etc., but the temperature of the etching solution is higher. The temperature is preferably 60 to 85 ° C, more preferably 70 to 85 ° C.

In the etching method of the present invention, a part or all of the inorganic filler filled with a high content is gradually dissolved from the surface layer of the resin composition layer, and the alkali-insoluble resin and the organic filler are dispersed. Removal of the resin composition layer proceeds.

In the etching method of the present invention, methods such as dipping treatment, paddle treatment, spray treatment, brushing, and scraping can be used for the pretreatment step and the etching step. Among these, the immersion treatment is preferable from the viewpoint of the uniformity of the etching treatment.

In the etching method of the present invention, after the resin composition is removed by the etching step, the etching solution remaining on the surface of the resin composition is washed, and the resin adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 It is preferable to carry out a washing step in order to remove the residue 8. It is preferable that the washing step is an ultrasonic irradiation step of irradiating ultrasonic waves. Ultrasonic irradiation is preferably performed by a dipping method. In ultrasonic irradiation, it is preferable that the resin residue 8 adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 is brought into contact with water subjected to ultrasonic vibration of 20 to 150 kHz for 10 to 300 seconds. Here, when the frequency of ultrasonic vibration is less than 20 kHz or exceeds 150 kHz, a special device is required and there is no great merit. Therefore, the frequency of ultrasonic vibration is preferably 20 to 150 kHz.

Further, when the time (contact time) for contacting the resin residue 8 adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 with the water subjected to ultrasonic vibration is less than 10 seconds, the resin residue 8 is sufficiently applied. It may not be possible to remove it. If the contact time exceeds 300 seconds, the time may be too long and the productivity may decrease. Therefore, the contact time is preferably 10 to 300 seconds. Further, in order to wash away the water washing water in which the organic filler is dispersed in the water washing step by ultrasonic irradiation, it is preferable to combine the water washing step by the immersion type ultrasonic irradiation and then the water washing step by the spray method. The spray pressure is preferably 0.02 to 0.3 MPa.

As the flush water, tap water, industrial water, pure water or the like can be used. Of these, it is preferable to use pure water. As the pure water, those generally used for industrial purposes can be used. Further, the temperature of the washing water is preferably equal to or lower than the temperature of the etching solution, and the temperature difference between the etching solution and the washing water is preferably 40 to 50 ° C.

When the etching resist 5 is used in the etching step, a dry film resist pattern can be used as the etching resist 5 in addition to the metal mask described above.

The dry film resist according to the present invention contains at least a photocrosslinkable resin composition, and a photocrosslinkable resin is coated on a carrier film such as polyester to form a photocrosslinkable resin layer, and in some cases, protection of polyethylene or the like. The structure is such that the photocrosslinkable resin layer is coated with a film. The photocrosslinkable resin layer contains, for example, a binder polymer containing a carboxyl group, a photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule, a photopolymerization initiator, a solvent, and other additives. To do. The blending ratio thereof is determined by the balance of required properties such as sensitivity, resolution, and degree of cross-linking. Examples of photocrosslinkable resin compositions are "Photopolymer Handbook" (edited by Photopolymer Association, published in 1989, published by Industrial Research Association Co., Ltd.) and "Photopolymer Technology" (edited by Ao Yamamoto and Mototaro Nagamatsu, 1988). It is described in (published by Nikkan Kogyo Shimbun), etc., and a desired photocrosslinkable resin composition can be used. The thickness of the photocrosslinkable resin layer is preferably 15 to 100 μm, more preferably 20 to 50 μm.

The dry film resist exposure method according to the present invention includes a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a reflected image exposure using a UV fluorescent lamp as a light source, a single-sided or double-sided close contact exposure using a photomask, and a proxy. Examples include the Miti method, the projection method, and laser scanning exposure. When scanning exposure is performed, a laser light source such as a He-Ne laser, a He-Cd laser, an argon laser, a krypton ion laser, a ruby laser, a YAG laser, a nitrogen laser, a dye laser, or an excima laser is used according to the emission wavelength. It can be exposed by wavelength conversion and scanning exposure, or by scanning exposure using a liquid crystal shutter or a micromirror array shutter.

As a method for developing a dry film resist according to the present invention, an unnecessary dry film resist (unexposed) is sprayed from the vertical direction of the substrate toward the surface of the substrate by using a developing solution suitable for the photocrosslinkable resin layer to be used. Part) is removed to form an etching resist 5 composed of a dry film resist pattern. As the developing solution, generally, 1 to 3% by mass of an aqueous sodium carbonate solution is used, and more preferably 1% by mass of an aqueous sodium carbonate solution is used.

As a method for peeling the dry film resist pattern used as the etching resist 5, a stripping solution suitable for the photocrosslinkable resin layer to be used is used, and the dry film resist pattern is sprayed from the vertical direction of the substrate toward the surface of the substrate. Remove. As the stripping solution, generally 2 to 4% by mass of an aqueous sodium hydroxide solution is used, and more preferably 3% by mass of an aqueous sodium hydroxide solution is used.

In the present invention, the alkali-insoluble resin, the inorganic filler, and the organic filler can be dispersed and removed at the same time by keeping the time from the end of the etching process to the start of the water washing process, which is the next step, within 30 seconds. The mechanism of this effect is beyond speculation, but it is believed that the dispersion state of the alkali-insoluble resin, the inorganic filler, and the organic filler remaining in the etching treatment portion immediately after the etching step is related. Immediately after the etching process, the alkali-insoluble resin, the inorganic filler, and the organic filler remaining in the etching treatment portion are in a dispersed state in which they are mixed with each other, and the resin composition is formed by promptly performing a water washing step in this dispersed state. The layer can be removed without residue. However, when the time from the end of the etching process to the start of the washing process exceeds 30 seconds, the components that are easily removed by washing with water and the components that are difficult to remove are due to the progress of separation of the alkali-insoluble resin, the inorganic filler, and the organic filler. It is considered that the resin composition layer is left behind after washing with water.

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

(Examples 1-1-1-12, 1-14, 1-17-1-22)
25% by mass of PTFE as an organic filler, 40% by mass of spherical molten silica as an inorganic filler, 16% by mass of a biphenyl aralkyl type epoxy resin as an epoxy resin, 16% by mass of a phenol novolac type cyanate resin as a heat curing agent, curing acceleration As an agent, 2% by mass of triphenylphosphine, a coupling agent, and a leveling agent were added, and the total amount was 100% by mass, and methyl ethyl ketone and cyclohexanone were mixed as a medium to obtain a liquid resin composition.

Next, the liquid resin composition was applied onto a polyethylene terephthalate film (thickness 38 μm) and then dried at 100 ° C. for 5 minutes to remove the medium. As a result, an A-stage resin composition layer composed of an alkali-insoluble resin, an inorganic filler, and a resin composition containing an organic filler was formed with a film thickness of 20 μm.

Subsequently, a peelable metal foil in which a copper foil 6 having a thickness of 3 μm, a release layer, and a carrier foil were laminated in this order was prepared, and both were thermocompression bonded so that the copper foil and the resin composition layer were in contact with each other. After that, the release layer and the carrier foil were peeled off to obtain a resin composition layer 4 with a copper foil 6.

A conductor pattern was formed by patterning the copper foil 3'on one surface of an epoxy resin glass cloth base copper-clad laminate 1'(area 170 mm x 255 mm, copper foil thickness 12 μm, base material thickness 0.1 mm). An epoxy resin glass cloth base material (circuit board 1) was obtained. Next, the polyethylene terephthalate film was peeled off from the resin composition layer 4 with the copper foil 6, and a vacuum thermocompression bonding laminator was used on the epoxy resin glass cloth base material on which the conductor pattern was formed, at a temperature of 100 ° C. and a pressure of 1. After vacuum thermocompression bonding at 0.0 MPa, it was heated at 130 ° C. for 45 minutes to form a B-stage resin composition layer 4.

Subsequently, the copper foil 6 on the resin composition layer 4 was patterned, an opening was formed in a predetermined region of the copper foil, and the resin composition layer 4 with an etching resist (metal mask) was prepared.

Next, an etching step was performed by dipping the resin composition layer 4 at 80 ° C. with the etching solutions shown in Tables 1 and 2 via the etching resist 5. After the etching step, the etching solution remaining on the surface of the resin composition layer 4 is washed, and the resin residue 8 adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 is removed by irradiating ultrasonic waves. Therefore, as a washing step, an ultrasonic irradiation step of a dipping method with pure water was performed. The ultrasonic irradiation step was performed by bringing the resin residue 8 adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 into contact with pure water subjected to ultrasonic vibration of 45 kHz for 60 seconds.

Regarding the etching solution treatment time, a + 2b = in the opening length a of the etching resist 5 and the film thickness b of the resin composition layer 4 and the bottom length c of the opening of the resin composition layer 4 shown in FIG. The processing time to be c was defined as "standard processing time". Specifically, since the opening length a of the etching resist 5 is 60 μm and the film thickness b of the resin composition layer 4 is 20 μm, the bottom length c of the opening of the resin composition layer 4 is 100 μm ± 5 μm. The processing time is defined as “standard processing time” and is shown in Tables 1 and 2.

(Resin residue)
It was evaluated whether the resin composition layer 4 was surely removed inside the opening of the etching resist 5. The results are shown in Tables 1 and 2. The evaluation criteria are shown below.

Evaluation Criteria ○ (Good): A level at which no resin residue remains inside the opening after ultrasonic water washing, or even if it remains, it can be removed by an additional water washing process using a spray.
Δ (Satisfaction): A level at which resin residue remains inside the opening after ultrasonic washing and cannot be removed by an additional washing step with a spray, but can be easily removed by a post-treatment such as a plasma washing treatment.
× (Unsatisfaction): A level at which a large amount of resin residue remains inside the opening after ultrasonic washing and is not removed by post-treatment such as plasma washing treatment.

(Example 1-13)
Etching treatment by the same method as in Example 1-3 except that the content of PTFE was 23% by mass, the content of spherical fused silica was 33% by mass, and the content of biphenyl aralkyl type epoxy resin was 25% by mass. Was done. The results are shown in Table 2.

(Example 1-15)
Etching treatment by the same method as in Example 1-3 except that the content of PTFE was 15% by mass, the content of spherical fused silica was 40% by mass, and the content of biphenyl aralkyl type epoxy resin was 26% by mass. Was done. Although the etching time was extended to 30 minutes (1800 seconds), the resin composition layer could not be etched due to a large amount of resin residue on the surface of the conductor pattern and on the epoxy resin glass cloth substrate. The results are shown in Table 2.

(Example 1-16)
Etching treatment by the same method as in Example 1-3 except that the content of PTFE was 25% by mass, the content of spherical fused silica was 25% by mass, and the content of biphenyl aralkyl type epoxy resin was 31% by mass. Was done. Although the etching time was extended to 30 minutes, the resin composition layer could not be etched due to a large amount of resin residue on the surface of the conductor pattern and on the epoxy resin glass cloth base material. The results are shown in Table 2.

(Example 1-23)
The resin composition layer 4 with the etching resist obtained by the same method as in Example 1-1 was wet-blasted, and then the etching resist 5 was removed. As a result of observing this with an optical microscope, there was a variation in the etching amount of the resin composition layer 4, and there was a place where the resin composition remained on the epoxy resin glass cloth base material. In addition, many scratches made by the wet blast treatment were confirmed on the conductor pattern in which a part or all of the surface was exposed.

(Examples 2-1 to 2-14)
In the water washing step after the etching treatment, the resin residue when the etching process was performed by the same etching method as in Examples 1-1 to 1-14 except that the water washing step by spraying was performed instead of the ultrasonic irradiation step. The evaluation results of are shown in Tables 3 and 4.

As can be seen from the results in Tables 1 to 4, in the present invention, the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler can be efficiently removed (particularly, stably removed without any resin residue). it can.

(Examples 3-13-10, 3-12, 3-15-3-21)
The etching treatment was performed in the same manner as in Example 1-1 except that the etching solutions shown in Table 5 or Table 6 were used. The results are shown in Tables 5 and 6.

(Example 3-11)
Etching treatment by the same method as in Example 3-3 except that the content of PTFE was 23% by mass, the content of spherical fused silica was 33% by mass, and the content of biphenyl aralkyl type epoxy resin was 25% by mass. Was done. The results are shown in Table 6.

(Example 3-13)
Etching treatment by the same method as in Example 3-3 except that the content of PTFE was 15% by mass, the content of spherical fused silica was 40% by mass, and the content of biphenyl aralkyl type epoxy resin was 26% by mass. Was done. Although the etching time was extended to 30 minutes (1800 seconds), the resin composition layer could not be etched due to a large amount of resin residue on the surface of the conductor pattern and on the epoxy resin glass cloth substrate. The results are shown in Table 6.

(Example 3-14)
Etching treatment by the same method as in Example 3-3 except that the content of PTFE was 25% by mass, the content of spherical fused silica was 25% by mass, and the content of biphenyl aralkyl type epoxy resin was 31% by mass. Was done. Although the etching time was extended to 30 minutes, the resin composition layer could not be etched due to a large amount of resin residue on the surface of the conductor pattern and on the epoxy resin glass cloth base material. The results are shown in Table 6.

(Examples 4-1 to 4-12)
In the water washing step after the etching treatment, the resin residue when the etching process was performed by the same etching method as in Examples 3-1 to 3-12 except that the water washing step by spraying was performed instead of the ultrasonic irradiation step. The evaluation results of are shown in Tables 7 and 8.

As can be seen from the results in Tables 5 to 8, in the present invention, it is possible to efficiently remove the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler (particularly, stably remove the resin composition without any resin residue). it can.

(Examples 5-1 to 5-10, 5-12, 5-15 to 5-22)
The etching treatment was performed in the same manner as in Example 1-1 except that the etching solutions shown in Table 9 or Table 10 were used. The results are shown in Tables 9 and 10.

(Example 5-11)
Etching treatment by the same method as in Example 5-3 except that the content of PTFE was 23% by mass, the content of spherical fused silica was 33% by mass, and the content of biphenyl aralkyl type epoxy resin was 25% by mass. Was done. The results are shown in Table 10.

(Example 5-13)
Etching treatment by the same method as in Example 5-3 except that the content of PTFE was 15% by mass, the content of spherical fused silica was 40% by mass, and the content of biphenyl aralkyl type epoxy resin was 26% by mass. Was done. Although the etching time was extended to 30 minutes (1800 seconds), the resin composition layer could not be etched due to a large amount of resin residue on the surface of the conductor pattern and on the epoxy resin glass cloth substrate. The results are shown in Table 10.

(Example 5-14)
Etching treatment by the same method as in Example 5-3 except that the content of PTFE was 25% by mass, the content of spherical fused silica was 25% by mass, and the content of biphenyl aralkyl type epoxy resin was 31% by mass. Was done. Although the etching time was extended to 30 minutes, the resin composition layer could not be etched due to a large amount of resin residue on the surface of the conductor pattern and on the epoxy resin glass cloth base material. The results are shown in Table 10.

(Examples 6-1 to 6-12)
In the water washing step after the etching treatment, the resin residue when the etching process was performed by the same etching method as in Examples 5-1 to 5-12 except that the water washing step by spraying was performed instead of the ultrasonic irradiation step. The evaluation results of are shown in Tables 11 and 12.

As can be seen from the results in Tables 9 to 12, in the present invention, the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler is efficiently removed (particularly, stably removed without any resin residue). Can be done.

(Example 7)
25% by mass of PTFE as an organic filler, 40% by mass of spherical molten silica as an inorganic filler, 16% by mass of a biphenyl aralkyl type epoxy resin as an epoxy resin, 16% by mass of a phenol novolac type cyanate resin as a heat curing agent, curing acceleration As an agent, 2% by mass of triphenylphosphine, a coupling agent, and a leveling agent were added, and the total amount was 100% by mass, and methyl ethyl ketone and cyclohexanone were mixed as a medium to obtain a liquid resin composition.

Next, the liquid resin composition was applied onto a polyethylene terephthalate film (thickness 38 μm) and then dried at 100 ° C. for 5 minutes to remove the medium. As a result, an A-stage resin composition layer composed of an alkali-insoluble resin, an organic filler, and a resin composition containing an inorganic filler was formed with a film thickness of 20 μm.

Subsequently, a peelable metal foil in which a copper foil 6 having a thickness of 3 μm, a release layer, and a carrier foil were laminated in this order was prepared, and both were thermocompression bonded so that the copper foil and the resin composition layer were in contact with each other. After that, the release layer and the carrier foil were peeled off to obtain a resin composition layer 4 with a copper foil 6.

A conductor pattern was formed by patterning the copper foil 3'on one surface of an epoxy resin glass cloth base copper-clad laminate 1'(area 170 mm x 255 mm, copper foil thickness 12 μm, base material thickness 0.1 mm). An epoxy resin glass cloth base material (circuit board 1) was obtained. Next, the polyethylene terephthalate film was peeled off from the resin composition layer 4 with the copper foil 6, and a vacuum thermocompression bonding laminator was used on the epoxy resin glass cloth base material on which the conductor pattern was formed, at a temperature of 100 ° C. and a pressure of 1. After vacuum thermocompression bonding at 0.0 MPa, it was heated at 130 ° C. for 45 minutes to form a B-stage resin composition layer 4.

Subsequently, the copper foil 6 on the resin composition layer 4 was patterned, an opening was formed in a predetermined region of the copper foil 6, and the resin composition layer 4 with the etching resist 5 (metal mask) was prepared.

After each of the pretreatment liquids (30 ° C.) shown in Table 13 was brought into contact with the resin composition layer 4 and the metal mask 5 by an immersion treatment for 5 minutes, a spray-type water washing treatment with pure water was performed for 1 minute. After improving the affinity between the etching solution and the resin composition layer 4, the resin composition layer 4 is etched by a dipping treatment at 80 ° C. with each etching solution shown in Table 14 via the metal mask 5. Processing was performed. After the etching treatment, the etching solution remaining on the surface of the resin composition layer 4 is washed, and the resin residue 8 adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 is removed by irradiating ultrasonic waves. Therefore, ultrasonic washing with pure water was performed. The ultrasonic washing was carried out by bringing the resin residue 8 adhering to the surface of the connection pad 3 and the wall surface of the resin composition layer 4 into contact with water subjected to ultrasonic vibration of 45 kHz for 60 seconds.

Regarding the etching solution treatment time, a + 2b = in the opening length a of the metal mask 5 and the film thickness b of the resin composition layer 4 and the bottom length c of the opening of the resin composition layer 4 shown in FIG. The processing time that became c was defined as the "standard processing time". Specifically, since the opening length a of the metal mask 5 is 50 μm and the film thickness b of the resin composition layer 4 is 20 μm, the bottom length c of the opening of the resin composition layer 4 is 90 μm ± 5 μm. The processing time is defined as “standard processing time” and is shown in Tables 13 and 14. The pH of each pretreatment solution was adjusted using sulfuric acid or potassium hydroxide.

(Small diameter opening)
From the confirmation of 100 openings of the metal mask 5 when the opening length a of the metal mask 5 is 50 μm and the film thickness b of the resin composition layer 4 is 20 μm, the bottom length of the openings of the resin composition layer 4 It was evaluated based on the following criteria whether or not the small-diameter opening treatment was performed when the c was 90 μm ± 5 μm. The results are shown in Table 15.

Evaluation Criteria ◯ (Good): Of the 100 small-diameter openings in the standard processing time, the resin openings are 95 or more.
Δ (Satisfaction): Of the 100 small-diameter openings in the standard processing time, the resin openings are 85 or more and less than 95.
X (Unsatisfaction): Of the 100 small-diameter openings in the standard processing time, the number of resin openings is less than 85.

As can be seen from the results in Table 15, in the present invention, the unetched portion even in the small-diameter opening treatment such that the opening diameter of the opening in the resin composition layer containing the alkali-insoluble resin, the organic filler and the inorganic filler is Φ100 μm or less. Can be suppressed and etched.

(Examples 8-1 to 8-9)
25% by mass of PTFE as an organic filler, 40% by mass of spherical molten silica as an inorganic filler, 16% by mass of a biphenyl aralkyl type epoxy resin as an epoxy resin, 16% by mass of a phenol novolac type cyanate resin as a heat curing agent, curing acceleration As an agent, 2% by mass of triphenylphosphine, a coupling agent, and a leveling agent were added, and the total amount was 100% by mass, and methyl ethyl ketone and cyclohexanone were mixed as a medium to obtain a liquid resin composition.

Next, the liquid resin composition was applied onto a polyethylene terephthalate film (thickness 38 μm) and then dried at 100 ° C. for 5 minutes to remove the medium. As a result, an A-stage resin composition layer composed of an alkali-insoluble resin, an organic filler, and a resin composition containing an inorganic filler was formed with a film thickness of 20 μm.

Subsequently, a peelable metal foil in which a copper foil 6 having a thickness of 3 μm, a release layer, and a carrier foil were laminated in this order was prepared, and both were thermocompression bonded so that the copper foil and the resin composition layer were in contact with each other. After that, the release layer and the carrier foil were peeled off to obtain a resin composition layer 4 with a copper foil 6.

The copper foil 3'on one surface of the epoxy resin glass cloth base copper-clad laminate 1'(area 400 mm x 500 mm, copper foil thickness 12 μm, base material thickness 0.1 mm) is patterned, and the conductor pattern A is a surface. An epoxy resin glass cloth base material (circuit board 1) was obtained in which 10 pieces were uniformly arranged in the horizontal direction and 12 pieces in the vertical direction. Next, the polyethylene terephthalate film was peeled off from the resin composition layer 4 with the copper foil 6, and a vacuum thermocompression bonding laminator was used on the epoxy resin glass cloth base material on which the conductor pattern A was formed, at a temperature of 100 ° C. and a pressure. After vacuum thermocompression bonding at 1.0 MPa, it was heated at 130 ° C. for 45 minutes to form a B-stage resin composition layer 4.

Subsequently, the copper foil 6 on the resin composition layer 4 was patterned, an opening was formed in a predetermined region of the copper foil 6, and the resin composition layer 4 with the etching resist (metal mask) 5 was prepared.

Next, an etching step was carried out by dipping the resin composition layer 4 at 80 ° C. with the etching solution shown in Table 16 via the etching resist 5. Next, after the "time from the end of the etching process to the start of the washing process" shown in Table 16, the alkali-insoluble resin, the organic filler, and the inorganic filler remaining in the etching treatment portion by the ultrasonic irradiation of the immersion method with pure water are removed. A washing step of washing with water was carried out. Then, it was further washed by spray treatment with pure water.

Whether or not the resin composition layer 4 was reliably removed at the opening of the etching resist 5 was evaluated by "resin residue". In addition, "undercut" was evaluated as an evaluation of the deformation of the resin composition layer 4 in the opening shape. Furthermore, as an evaluation of "in-plane uniformity", 120 openings having the same target opening diameter (target opening diameter) were observed, and the opening diameter of the opening having the maximum opening diameter was set to "maximum". "Value", the opening diameter of the opening with the smallest opening diameter is set as the "minimum value", and the fluctuation value (%) is calculated by "(maximum value-minimum value) / target opening diameter x 100", and "in-plane uniformity" is obtained. Was evaluated. The results are shown in Table 16. The criteria for each evaluation are shown below.

(Evaluation criteria for resin residue)
◯ (Very Good): No resin composition remains on the surface.
○ △ (Good): A very small amount of resin composition remains on the surface, but this is not a problem.
Δ (Satisfaction): A small amount of resin composition remains on the surface, but it is a level that can be easily removed by plasma cleaning treatment.
X (Unsatisfaction): A level at which a large amount of resin composition remains on the surface after etching and is not removed by the plasma cleaning treatment.

(Undercut evaluation criteria)
◯ (Very Good): No undercut is observed in the resin composition layer.
◯ Δ (Good): A very small undercut is seen on the bottom surface of the resin composition layer.
Δ (Satisfaction): A level at which a small undercut is seen on the bottom surface of the resin composition layer, but this is not a problem.
X (Unsatisfaction): A large undercut that poses a practical problem is seen on the bottom surface of the resin composition layer.

(Evaluation criteria for in-plane uniformity)
◯ (Very Good): Very high uniformity. The fluctuation value is less than 3%.
○ △ (Good): High uniformity. The fluctuation value is 3% or more and less than 5%.
Δ (Satisfaction): Uniform. The fluctuation value is 5% or more and less than 6%.
× (Unsatisfaction): Not uniform. The fluctuation value is 6% or more.

As can be seen from the results in Table 16, in the etching method for etching a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler, and 30 to 50% by mass of an inorganic filler, the etching solution of the present invention. It can be seen that the in-plane uniformity is high by including the etching step and the washing step in this order. It can also be seen that the occurrence of undercuts is small. Then, it can be seen that the time from the end of the etching process to the start of the washing process is within 30 seconds, so that the residue of the resin composition is small and can be stably removed.

(Example 9-1 to 9-8)
25% by mass of PTFE as an organic filler, 40% by mass of spherical molten silica as an inorganic filler, 16% by mass of a biphenyl aralkyl type epoxy resin as an epoxy resin, 16% by mass of a phenol novolac type cyanate resin as a heat curing agent, curing acceleration As an agent, 2% by mass of triphenylphosphine, a coupling agent, and a leveling agent were added, and the total amount was 100% by mass, and methyl ethyl ketone and cyclohexanone were mixed as a medium to obtain a liquid resin composition.

Next, the liquid resin composition was applied onto a polyethylene terephthalate film (thickness 38 μm) and then dried at 100 ° C. for 5 minutes to remove the medium. As a result, an A-stage resin composition layer composed of an alkali-insoluble resin, an inorganic filler, and a resin composition containing an organic filler was formed with a film thickness of 20 μm.

Subsequently, a peelable metal foil in which a copper foil 6 having a thickness of 3 μm, a release layer, and a carrier foil were laminated in this order was prepared, and both were thermocompression bonded so that the copper foil and the resin composition layer were in contact with each other. After that, the release layer and the carrier foil were peeled off to obtain a resin composition layer 4 with a copper foil 6.

A conductor pattern was formed by patterning the copper foil 3'on one surface of an epoxy resin glass cloth base copper-clad laminate 1'(area 170 mm x 255 mm, copper foil thickness 12 μm, base material thickness 0.1 mm). An epoxy resin glass cloth base material (circuit board 1) was obtained. Next, the polyethylene terephthalate film was peeled off from the resin composition layer 4 with the copper foil 6, and a vacuum thermocompression bonding laminator was used on the epoxy resin glass cloth base material on which the conductor pattern was formed, at a temperature of 100 ° C. and a pressure of 1. After vacuum thermocompression bonding at 0.0 MPa, it was heated at 130 ° C. for 45 minutes to form a B-stage resin composition layer 4.

Subsequently, the copper foil 6 on the resin composition layer 4 was patterned, an opening was formed in a predetermined region of the copper foil, and the resin composition layer 4 with an etching resist (metal mask) was prepared.

The resin composition layer 4 was subjected to an etching treatment by an immersion treatment at 80 ° C. with the etching solution shown in Table 17 via the etching resist 5. After the etching treatment, a cleaning step was performed to remove the etching solution remaining on the surface of the resin composition layer 4. In the cleaning process, a spray method using pure water was used.

Regarding the etching solution treatment time, a + 2b = in the opening length a of the etching resist 5 and the film thickness b of the resin composition layer 4 and the bottom length c of the opening of the resin composition layer 4 shown in FIG. The processing time to be c was defined as "standard processing time". Specifically, since the opening length a of the etching resist 5 is 50 μm and the film thickness b of the resin composition layer 4 is 20 μm, the bottom length c of the opening of the resin composition layer 4 is 90 μm ± 5 μm. The processing time is defined as “standard processing time” and is shown in Table 17.
Whether or not the resin composition layer 4 was reliably removed inside the opening of the metal mask 5 was evaluated by the above-mentioned "resin residue". The results are shown in Table 17.

As can be seen from the results in Table 17, in the present invention, the resin composition containing the alkali-insoluble resin, the organic filler and the inorganic filler can be efficiently removed (particularly, stably removed without any resin residue). In particular, by using an aromatic alcohol, the resin composition could be efficiently removed without using ultrasonic water washing.

In the etching solution and etching method of the present invention, an insulating resin composition layer filled with a high content of an organic filler and an inorganic filler and having excellent heat resistance, dielectric properties, mechanical strength, chemical resistance, etc. is etched. For example, it can be applied to fine processing of insulating resin in a multilayer build-up wiring board, a module board with built-in components, a flip chip package board, a motherboard for mounting a package board, and the like.

1 Circuit board 1'Copper laminated board 2 Insulation layer 3 Solder connection pad, Connection pad 3'Copper foil 4 Resin composition layer 5 Etching resist (metal mask, dry film resist pattern)
6 Copper foil, dry film resist 8 Resin residue a Opening length of etching resist 5 b Thickness of resin composition layer 4 c Bottom length of resin composition layer 4

Claims (14)

In an etching solution of a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler and 30 to 50% by mass of an inorganic filler, the etching solution is 15 to 45% by mass of alkali as a first component. Etching characterized by containing a metal hydroxide and 1 to 40% by mass of an ethanolamine compound as a second component, and containing at least one third component selected from an alcohol compound and a carboxylic acid compound. liquid. The etching solution according to claim 1, wherein the third component contains at least one selected from a polyol compound, a polyvalent carboxylic acid compound, and a hydroxy acid compound. The etching solution according to claim 1 or 2, wherein the third component contains 3 to 60% by mass of a polyol compound. The etching solution according to claim 2 or 3, wherein the polyol compound has a molecular weight of 80 or more and 200 or less. The etching solution according to any one of claims 2 to 4, wherein the polyol compound has three or more hydroxyl groups. The etching solution according to any one of claims 2 to 5, wherein the polyol compound contains glycerin. The etching solution according to any one of claims 1 to 6, wherein the third component contains 2 to 20% by mass of a polyvalent carboxylic acid compound. The etching solution according to any one of claims 1 to 7, wherein the third component contains 2 to 20% by mass of a hydroxy acid compound. The etching solution according to any one of claims 1 to 8, wherein the etching solution contains 0.1 to 3% by mass of an aromatic alcohol compound. A step of etching a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler, and 30 to 50% by mass of an inorganic filler using the etching solution according to any one of claims 1 to 9. A method for etching a resin composition, which comprises. Etching that uses the etching solution according to any one of claims 1 to 9 to etch a resin composition containing an alkali-insoluble resin, 20 to 40% by mass of an organic filler, and 30 to 50% by mass of an inorganic filler. A method for etching a resin composition, which comprises a step and an ultrasonic irradiation step of irradiating ultrasonic waves after the etching step. The resin composition according to claim 10 or 11, further comprising a step of pretreating with a pretreatment liquid consisting of an acidic aqueous solution containing 2.5 to 7.5% by mass of anionic surfactant before the etching step. Etching method. The method for etching a resin composition according to any one of claims 10 to 12, which has a washing step after the etching step and the time from the end of the etching step to the start of the washing step is within 30 seconds. The method for etching a resin composition according to any one of claims 10 to 13, wherein an etching resist is used in the etching step, and the etching resist is a metal mask or a dry film resist.

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