WO2018186362A1

WO2018186362A1 - Etchant for resin composition and etching method

Info

Publication number: WO2018186362A1
Application number: PCT/JP2018/014156
Authority: WO
Inventors: 豊田　裕二; 昌大田邉
Original assignee: 三菱製紙株式会社
Priority date: 2017-04-06
Filing date: 2018-04-02
Publication date: 2018-10-11
Also published as: JP6929936B2; TW201842165A; CN110461920A; JPWO2018186362A1; KR20190120771A; KR102340959B1

Abstract

The present invention addresses the problem of providing an etchant or etching method which, when used in processing for removing a resin composition comprising an alkali-insoluble resin and an inorganic filler, is capable of removing only a resin composition layer comprising said resin composition, while preventing the resin composition layer from heating up excessively to cause defects. The etchant, which is for a resin composition comprising an alkali-insoluble resin and 50-80 mass% inorganic filler, contains 15-45 mass% alkali metal hydroxide. More preferably, the etchant further contains 5-40 mass% ethanolamine compound. The etching method comprises using the etchant to remove the resin composition comprising an alkali-insoluble resin and an inorganic filler.

Description

Etching solution and etching method for resin composition

The present invention relates to an etching solution and etching method for a resin composition containing an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler.

In recent years, with the miniaturization and high performance of electronic devices, there is a strong demand for the formation of fine wiring and a reduction in the thermal expansion coefficient in circuit boards. Among them, as a means for reducing the thermal expansion coefficient 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. Furthermore, it has been proposed to use an alkali-insoluble resin having excellent moisture resistance, including an epoxy resin, a phenol novolac curing agent, a phenoxy resin, a cyanate resin, and the like as an insulating material. Insulating resin compositions containing these inorganic fillers and alkali-insoluble resins have excellent physical properties such as heat resistance, dielectric properties, mechanical strength, and chemical resistance, and are used for the outer layer surface of circuit boards. Widely used as an interlayer insulating material used for resists and multilayer build-up wiring boards.

FIG. 1 is a schematic cross-sectional structure diagram of a solder resist pattern in which a portion other than connection pads 3 to be soldered on a circuit board is covered with a 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 the connection pad 3. The structure shown in FIG. 2 is said to be an NSMD (Non Solder Masked Defined) structure, and is characterized in that the opening of the resin composition layer 4 is larger than the connection 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 a resin composition containing an inorganic filler and an alkali-insoluble resin, a known method such as drilling, laser, plasma, blasting or the like can be used. Moreover, these methods can also be combined as needed. Among them, processing by a laser such as a carbon dioxide laser, excimer laser, UV laser, YAG laser, etc. 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 openings for forming via holes and openings for forming connection pads 3 can be formed (see, for example, Patent Documents 1 and 2).

However, in processing by laser light irradiation, for example, when a carbon dioxide laser is used, a large number of shots are required, and desmear treatment is performed using an oxidizing agent composed of an aqueous solution such as chromic acid or permanganate as a post-treatment. Need to do. Moreover, when an excimer laser is used, the time required for processing becomes very long. Furthermore, in the case of a UV-YAG laser, there is an advantage in that fine processing can be performed as compared with other laser beams, but not only the resin composition layer but also a nearby metal layer is removed at the same time. There was a problem.

In addition, when the resin composition layer is irradiated with laser light, light energy is absorbed by the object at the irradiated part, and the object excessively generates heat according to the specific heat, and this heat generation causes the resin to dissolve, deform, alter, and discolor. In some cases, such defects may occur. In addition, it has been proposed to use a thermosetting resin in the resin composition layer against this heat generation, but if the thermosetting resin is used, cracks may easily occur in the resin composition layer. .

As a method other than the laser beam irradiation, a method of removing the resin composition layer by a wet blast method may be mentioned. After forming a resin composition layer on a circuit board having a connection pad on an insulating substrate, applying a curing treatment, and providing a resin layer for forming a wet blast mask on the resin composition layer, By performing exposure and development, a patterned wet blast mask is formed. Next, the resin composition layer is removed by wet blasting to form an opening, and then the wet blasting mask is removed (see, for example, Patent Document 3).

However, in the processing by wet blasting, the thickness that can be polished by one blasting is small, and it is necessary to repeat blasting multiple times. Therefore, not only does the time required for polishing become very long, but it is also difficult to make the in-plane polishing amount uniform. Further, it is extremely difficult to perform processing with high accuracy so that the resin composition layer residue is not left on the connection pad or the insulating substrate, and is completely exposed.

JP 2003-101244 A International Publication No. 2017/038713 Pamphlet JP 2008-300691 A

In the process of removing the resin composition containing the alkali-insoluble resin and the inorganic filler, the resin composition layer containing the resin composition is free from defects due to excessive heat generation, and only the resin composition layer is removed. It is an object of the present invention to provide an etching solution and an etching method that can be performed.

The present inventors have found that the above problems can be solved by the following means.
<1> An etching solution for a resin composition containing an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler, characterized in that the etching solution contains 15 to 45% by mass of an alkali metal hydroxide. Etching solution.
<2> The resin composition according to <1>, wherein the alkali metal hydroxide is at least one compound selected from potassium hydroxide, sodium hydroxide, and lithium hydroxide. Etching solution.
<3> The resin composition according to <1> or <2>, wherein the inorganic filler is at least one selected from silica, glass, clay, and aluminum hydroxide. Etching solution.
<4> The etching solution according to any one of <1> to <3>, wherein the etching solution contains 5 to 40% by mass of an ethanolamine compound.
<5> The ethanolamine compound is at least selected from the group consisting of ethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, N-ethylethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine. <1> The etching solution according to <4>, which is one kind of compound.
<6> The ethanolamine compound is at least selected from the group consisting of ethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, N-ethylethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine. Etching solution for resin composition as described in <4>, which is a compound of two types.
<7> The etching solution for a resin composition according to <6>, which contains at least N- (β-aminoethyl) ethanolamine as the ethanolamine compound.
<8> In the method for etching a resin composition layer containing an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler, the resin composition layer is formed using the etching solution according to any one of <1> to <7>. An etching method comprising a step of removing.
<9> In a method for etching a resin composition layer containing an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler,
(A) a step of removing a part of the resin composition layer with the etching solution according to any one of <4> to <7>;
(B) a step of completely removing the remaining resin composition layer with a water washing removal solution containing an alkali metal hydroxide and an ethanolamine compound;
The etching method characterized by including these in this order. Here, the content of the alkali metal hydroxide in the water washing removal liquid is less than the content of the alkali metal hydroxide in the etching liquid. Moreover, the content of the ethanolamine compound in the water washing removal liquid is less than the content of the ethanolamine compound in the etching liquid.
<10> The etching method according to <8> or <9>, wherein the step of removing the resin composition layer is an immersion treatment.

A resin composition containing the resin composition without causing defects due to excessive heat generation in the process of removing the resin composition containing an alkali-insoluble resin and an inorganic filler by the etching solution and etching method of the present invention. Only the layer can be removed.

The schematic cross-section figure of a soldering resist pattern. The schematic cross-section figure of a soldering resist pattern. Sectional process drawing which shows an example of the etching method of this invention.

Hereinafter, modes for carrying out the present invention will be described. The etching solution of the present invention is an etching solution for a resin composition containing an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler, and is an alkaline aqueous solution containing 15 to 45% by mass of an alkali metal hydroxide. . Since alkali-insoluble resins have the property of not dissolving in alkaline aqueous solution, they cannot be removed by alkaline aqueous solution. However, the resin composition containing an 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 at a high content of 50 to 80% by mass is a high concentration alkali metal hydroxide. This is because it is dissolved and removed by the aqueous solution containing the.

When the content of the alkali metal hydroxide is less than 15% by mass, the solubility of the inorganic filler is poor, and when the content of the alkali metal hydroxide exceeds 45% by mass, the alkali metal hydroxide is precipitated. Since it is easy, it may be inferior to the stability of a liquid with time. The content of alkali metal hydroxide is more preferably 20 to 45% by mass, and further preferably 25 to 40% by mass.

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 as necessary. Examples of organic solvents include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetates 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 solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. Of these, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like are preferable because of the large swellability of the alkali-insoluble resin.

The etching solution of the present invention is an etching solution for a resin composition containing an alkali-insoluble resin and an inorganic filler. The content of the inorganic filler in the resin composition is 50 to 80% by mass with respect to 100% by mass of the nonvolatile content in the resin composition. When the content of the inorganic filler is less than 50% by mass, etching does not proceed because there are too few inorganic fillers as sites to be dissolved by the aqueous solution containing the alkali metal hydroxide with respect to the entire resin composition. . When content of an inorganic filler exceeds 80 mass%, there exists a tendency for flexibility to fall by the fall of the fluidity | liquidity of a resin composition, and it is inferior to practicality.

As the alkali metal hydroxide, at least one compound selected from the group consisting 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 may be used in combination.

Furthermore, the etching solution of the present invention preferably contains 5 to 40% by mass of an ethanolamine compound in addition to the alkali metal hydroxide. When an etching solution containing an ethanolamine compound is used, the ethanolamine compound penetrates into the resin composition, thereby promoting the swelling of the resin composition, accelerating the dissolution and removal of the inorganic filler, and the resin composition. Removal speed increases.

When the content of the ethanolamine compound is less than 5% by mass, the swellability of the alkali-insoluble resin is poor, and the removal rate of the resin composition does not change compared to the case where the content of the ethanolamine compound is 0% by mass. When the content of the ethanolamine compound exceeds 40% by mass, the compatibility with water becomes low and phase separation is likely to occur, so the etching solution may have poor stability over time. The content of the ethanolamine compound is more preferably 20 to 40% by mass, and further preferably 25 to 35% by mass.

The ethanolamine compound is a primary amine ethanolamine; a mixture of a primary amine and a secondary amine (that is, having a primary amino group and a secondary amino group in one molecule). N- (β-aminoethyl) ethanolamine; secondary amine N-methylethanolamine, N-ethylethanolamine; tertiary amine N-ethyldiethanolamine and N-methyldiethanolamine At least one kind of compound is preferably used. As the ethanolamine compound, one of these may be used alone, or two or more may be used in combination. When two or more types are used in combination, one of them is preferably N- (β-aminoethyl) ethanolamine. This is because N- (β-aminoethyl) ethanolamine has a higher effect of promoting the swelling of the resin composition than other ethanolamine compounds.

The effect that can be achieved when the etching solution of the present invention contains two or more ethanolamine compounds will be described. Ethanolamine, which has a high effect of promoting the swelling of the resin composition, easily causes an undercut in the cross-sectional shape of the resin composition layer removed by etching. Therefore, an undercut suppression effect can be achieved by combining with an ethanolamine compound that has a low effect of promoting swelling of the resin composition.

Examples of ethanolamine having a high effect of promoting swelling of the resin composition include N- (β-aminoethyl) ethanolamine and N-methylethanolamine. Examples of the ethanolamine compound having a low effect of promoting the swelling of the resin composition include ethanolamine, N-ethylethanolamine, N-ethyldiethanolamine and the like.

The etching solution of the present invention is an alkaline aqueous solution. As water used for the etching solution of the present invention, tap water, industrial water, pure water, or the like can be used. Of these, it is preferable to use pure water. In the present invention, pure water generally used for industrial use can be used.

The etching solution of the present invention is preferably used in the range of 60 to 90 ° C. The optimum temperature differs depending on the type of the resin composition, the thickness of the resin composition layer containing the resin composition, the shape of the pattern obtained by processing to remove the resin composition, etc. More preferably, the temperature is 60 to 85 ° C, and further preferably 70 to 85 ° C.

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 Examples thereof include hydroxides such as aluminum oxide, magnesium hydroxide and calcium hydroxide; sulfates such as barium sulfate and calcium sulfate. 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 is dissolved in an aqueous solution containing an alkali metal hydroxide. Silica is more preferable in terms of excellent low thermal expansion, and spherical fused silica is particularly preferable. As the inorganic filler, one of these may be used alone, or two or more 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 not dissolved or dispersed in the aqueous alkali solution. Specifically, it is a resin having a very low content of a carboxyl group-containing resin or the like necessary for dissolving in an alkaline aqueous solution, and an acid value (JIS K2501) that serves as an index of the content of free carboxyl groups in the resin. : 2003) is less than 40 mg KOH / g. More specifically, the alkali-insoluble resin is a resin containing an epoxy resin and a thermosetting agent that cures the epoxy resin. Examples of alkaline aqueous solutions include alkali metal silicates, alkali metal hydroxides, alkali metal phosphates, alkali metal carbonates, ammonium phosphates, aqueous solutions containing inorganic alkaline compounds such as ammonium carbonate, monoethanolamine, Organics such as diethanolamine, triethanolamine, methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, trimethyl-2-hydroxyethylammonium hydroxide (choline) An aqueous solution containing an alkaline compound may 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 novolak 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 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 as a preferable one, a phenolic curing agent, a naphthol curing agent, an active ester curing agent, a benzoxazine curing agent, Examples include cyanate ester resins. As the thermosetting agent, one of these may be used alone, or two or more may be used in combination.

In addition to the above curing agent, a curing accelerator can be further contained. Examples of the curing accelerator include organic phosphine compounds, organic phosphonium salt compounds, imidazole compounds, amine adduct compounds, tertiary amine compounds, and the like. As the curing accelerator, one of these may be used alone, or two or more may be used in combination. In addition, when using cyanate ester resin as a thermosetting agent, you may add the organometallic compound used as a curing catalyst in order to shorten hardening time. Examples of the organic metal compound include an organic copper compound, an organic zinc compound, and an organic cobalt compound.

As described above, when an etching solution of the present invention is used to etch a resin composition containing an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler, the inorganic filler in the highly filled resin composition Is dissolved and removed by an aqueous solution containing a high concentration of alkali metal hydroxide, whereby the removal of the resin composition proceeds. Furthermore, when the etching solution of the present invention contains an ethanolamine compound, the ethanolamine compound penetrates into the resin composition, whereby the swelling of the resin composition is promoted and the dissolution and removal of the inorganic filler is accelerated. .

On the other hand, a resin composition containing an alkali-insoluble resin and an inorganic filler can form an insulating resin composition layer by thermosetting. However, etching using the etching solution of the present invention is A-stage (of curing reaction). It progresses in the state of B stage (intermediate stage of curing reaction) or before the start. Even in the A stage or the B stage, the alkali-insoluble resin is not dissolved or dispersed in the etching solution of the present invention, but the resin composition can be removed by dissolving and removing the inorganic filler with the etching solution of the present invention. proceed. In the state where the resin is completely cured in the C stage, even when the etching solution of the present invention contains an ethanolamine compound, the swelling of the resin composition layer by the ethanolamine compound is extremely small, and the inorganic filler is dissolved and removed. Etching is difficult.

The thermosetting conditions from the A stage to the B stage are 10 to 60 minutes at 100 to 160 ° C., more preferably 10 to 60 minutes at 100 to 130 ° C., but are not limited thereto. . When heated at a high temperature exceeding 160 ° C., thermosetting further proceeds and resin etching becomes difficult.

Hereinafter, the etching method of the present invention will be described. FIG. 3 is a cross-sectional process diagram illustrating an example of 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 pads 3 on the circuit board is covered with the resin composition layer 4 can be formed.

In step (I), the copper foil on the surface of the copper clad laminate is patterned by etching to form a conductor pattern, and the circuit board 1 having the solder connection pads 3 is formed.
In 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 by etching to form a metal mask 5 for etching the resin composition layer.
In step (IV), the resin composition layer 4 is etched through the metal mask 5 with the etching liquid for the resin composition layer until part or all of the solder connection pads 3 are exposed.

In the step (V), the metal mask 5 is removed by etching, and a solder resist pattern in which part or all of the solder connection pads 3 are covered with the resin composition layer 4 is formed.
The etching method <8> of the present invention includes a step of removing the resin composition layer with the etching liquid according to any one of the etching liquids <1> to <7> of the present invention.

Further, the etching method <9> of the present invention includes (A) a step of removing a part of the resin composition layer with the etching liquid according to any one of the etching liquids <4> to <7> of the present invention,
(B) Resin composition layer remaining by washing and removing liquid containing alkali metal hydroxide and ethanolamine compound, the contents of which are less than the contents of alkali metal hydroxide and ethanolamine compound in the etching solution, respectively. A step of completely removing
Are included in this order.

In the present invention <9>, the resin composition layer contains an alkali-insoluble resin and an inorganic filler, the content of the inorganic filler is 50 to 80% by mass with respect to the resin composition layer, and the inorganic filler is high. The resin composition layer is filled with the content. This inorganic filler is dissolved and removed by an etching solution which is an aqueous solution containing a high concentration alkali metal hydroxide of 15 to 45 mass%. Furthermore, when the ethanolamine compound contained in the etching solution penetrates into the resin composition layer, the swelling of the resin composition layer is promoted to accelerate the dissolution and removal of the inorganic filler, and the resin composition Increases layer removal rate.

Here, the removal of the resin composition layer proceeds when 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 is dispersed. Since the etching solution used in the step (A) in the etching method <9> of the present invention contains a high concentration alkali metal hydroxide of 15% by mass or more and has a large hydration power, the resin composition The alkali-insoluble resin in the deeper part of the layer is not dispersed, and the part close to the surface layer is removed. That is, “removing a part of the resin composition layer” in the step (A) means removing a part close to the surface layer of the resin composition layer.

Following the step (A), in the step (B), the treatment with a water washing removal liquid having a low content of alkali metal hydroxide promotes the dispersion of the alkali-insoluble resin, and the remaining resin composition layer is completely removed. Removed.

In the method for etching a resin composition layer according to the present invention <9>, the dissolution and removal of the inorganic filler with an aqueous solution containing an alkali metal hydroxide, and the penetration and swelling of the resin composition layer with an ethanolamine compound proceed continuously. However, the speed of progress varies depending on the type and content of the alkali metal hydroxide or the type and content of the ethanolamine compound.

The water washing removal liquid concerning the step (B) contains an alkali metal hydroxide and an ethanolamine compound, and their contents are less than the contents of the alkali metal hydroxide and the ethanolamine compound in the etching liquid, respectively. It is. The content of the alkali metal hydroxide and the ethanolamine compound in the water removal solution used in the step (B) is equal to or more than the content of the alkali metal hydroxide and the ethanolamine compound in the etching solution used in the step (A). In such a case, there arises a problem that it becomes difficult to control the etching amount of the resin composition layer. The alkali metal hydroxide and ethanolamine compound used in step (A) and the alkali metal hydroxide and ethanolamine compound used in step (B) may be the same or different. Although it is good, usually, two steps are performed continuously, and when the process shifts, considering that mixing from the etching solution in step (A) to the water washing removal solution in step (B) occurs, the same alkali Typically, metal hydroxides and ethanolamine compounds are included.

In the present invention <9>, the treatment temperature in step (A) is preferably 60 to 90 ° C., and the treatment temperature in step (B) is preferably 15 to 50 ° C. Here, the “treatment temperature” refers to the temperature of the etching solution used in the step (A) and the temperature of the water washing removal solution used in the step (B). The optimum processing temperature varies depending on the type of the resin composition, the thickness of the resin composition layer, the shape of the pattern obtained by performing the processing for removing the resin composition layer, and the like. The treatment temperature in the step (A) is more preferably 60 to 85 ° C, still more preferably 70 to 85 ° C. Further, the treatment temperature in the step (B) is more preferably 15 to 40 ° C., further preferably 15 to 30 ° C.

In the present invention <8> and <9>, a method such as immersion treatment, paddle treatment, spray treatment, brushing or scraping can be used for the step of removing the resin composition layer. Among these, immersion treatment is preferable. In a method other than the immersion treatment, bubbles are likely to be generated in the etching solution, and the bubbles may adhere to the surface of the resin composition layer and cause etching failure. Further, in the step (A) of the present invention <9>, the method other than the immersion treatment tends to cause a large change in the temperature of the etching solution, and the removal rate of the resin composition layer may vary.

After the step of removing the resin composition of the present invention <8> and the step (B) of the present invention <9>, the etching solution remaining on the surface of the resin composition layer is washed by washing with water. As a method of washing with water, a spray method is preferable from the viewpoint of diffusion rate and liquid supply uniformity. As flush water, tap water, industrial water, pure water or the like can be used. Of these, it is preferable to use pure water. Pure water that is generally used for industrial purposes can be used. Among these, it is preferable to use pure water. Pure water that is generally used for industrial purposes can be used. The temperature of the washing water is not more than the temperature of the etching solution, and the temperature difference is preferably 40 to 50 ° C., more preferably the temperature difference is 50 to 60 ° C.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to this Example.
(Examples 1 to 3)
As inorganic filler, fused silica 78% by mass, as epoxy resin, 10% by mass of biphenyl aralkyl type epoxy resin, as thermosetting agent, 10% by mass of phenol novolac type cyanate resin, as curing accelerator, 1% by mass of triphenylphosphine, In addition, a coupling agent and a leveling agent were added to a total amount of 100% by mass, and methyl ethyl ketone and cyclohexanone were mixed as a medium to obtain a liquid resin composition.

Next, after applying the liquid resin composition on a polyethylene terephthalate film (thickness 38 μm), the medium was removed by drying at 100 ° C. for 5 minutes. Thus, an A-stage resin composition layer having a film thickness of 20 μm and comprising a resin composition containing an alkali-insoluble resin and an inorganic filler was formed.

Subsequently, after preparing a peelable metal foil in which a copper foil having a thickness of 3 μm, a release layer, and a carrier foil are laminated in this order, and thermocompression bonding them so that the copper foil and the resin composition layer are in contact with each other The release layer and the carrier foil were peeled off to obtain a resin composition layer with a copper foil.

Epoxy resin on which a copper foil on one surface of an epoxy resin glass cloth base copper-clad laminate (area 170 mm × 255 mm, copper foil thickness 12 μm, base material thickness 0.1 mm) is patterned by etching to form a conductor pattern A glass cloth substrate was obtained. Next, the polyethylene terephthalate film is peeled from the resin composition layer with the copper foil, and the temperature is 100 ° C. and the pressure is 1.0 MPa using a vacuum thermocompression laminator on the epoxy resin glass cloth substrate on which the conductor pattern is formed. After vacuum thermocompression bonding, a B-stage resin composition layer was formed by heating at 100 ° C. for 30 minutes.

Subsequently, the copper foil on the resin composition layer is patterned by etching, an opening is formed in a predetermined region of the copper foil, and a resin composition layer with a metal mask is used as a metal mask for etching the resin composition layer. Got ready.

Next, the resin composition layer was subjected to an etching treatment by an immersion treatment with an etching solution described in Table 1 through a metal mask. After the etching treatment, the etching solution remaining on the surface of the resin composition layer was washed by a spray treatment with pure water. Table 1 shows the temperature of the etching solution and the time required for the etching process.

At the opening of the metal mask, “presence / absence of resin residue” and “presence / absence of undercut” were evaluated according to the following criteria.
(Presence or absence of resin residue on the conductor pattern surface)
○: No resin composition remains on the surface of the conductor pattern.
(Triangle | delta): Although the trace amount resin composition remains on the conductor pattern surface, the level which can be easily removed by post-processing, such as a plasma cleaning process.
X: Level at which many resin compositions remain on the surface of the conductor pattern and are not removed by post-treatment.
(Presence or absence of resin residue on epoxy resin glass cloth substrate)
○: No resin composition remains on the substrate.
(Triangle | delta): Although the trace amount resin composition remains on a base material, the level which can be easily removed by post-processes, such as a plasma cleaning process.
X: A level at which many resin compositions remain on the substrate and are not removed by post-treatment.
(With or without undercut)
A: Undercut is not seen in the resin composition layer.
○: A minute undercut is observed on the bottom surface of the resin composition layer.
Δ: A small undercut is observed on the bottom surface of the resin composition layer.
X: The big undercut which is a problem practically is seen by the bottom face of a resin composition layer.

Example 4
Etching was performed in the same manner as in Example 1 except that the content of fused silica was 65% by mass and the content of the biphenyl aralkyl epoxy resin was 23% by mass.
(Example 5)
Etching was performed in the same manner as in Example 1 except that the content of fused silica was 50% by mass and the content of the biphenyl aralkyl type epoxy resin was 38% by mass.
(Examples 6 to 8)
Etching was performed in the same manner as in Example 5 except that glass, clay, and aluminum hydroxide were used as the inorganic filler instead of fused silica.
(Examples 9 to 21)
Etching treatment was performed in the same manner as in Example 1 except that the etching solutions listed in Table 1 were used as the etching solution.
(Comparative Example 1)
Etching treatment was performed in the same manner as in Example 1 except that the content of fused silica was 48 mass% and the content of the biphenyl aralkyl type epoxy resin was 40 mass%. Although the etching time was extended to 30 minutes, a large amount of resin remained on the surface of the conductor pattern and on the epoxy resin glass cloth substrate, and the resin composition layer could not be etched. The results are shown in Table 2.
(Comparative Examples 2 to 4)
In Comparative Example 2, the content of potassium hydroxide in the etching solution was 10% by mass. In Comparative Examples 3 and 4, N- (β-aminoethyl) ethanolamine and N-methylethanolamine were further added as ethanolamine compounds. Etching was performed in the same manner as in Example 1 except that 40% by mass of each was added. Although the etching time was extended to 30 minutes, a large amount of resin remained on the surface of the conductor pattern and on the epoxy resin glass cloth substrate, and the resin composition layer could not be etched. The results are shown in Table 2.
(Comparative Example 5)
The resin composition layer with a metal mask obtained by the same method as in Example 1 was etched by a laser processing method, and then the mask pattern was removed. As a result of observing this with an optical microscope, there was a portion where the conductor pattern was removed, and defects such as deformation and alteration were confirmed in the resin composition layer.
(Comparative Example 6)
The resin composition layer with a metal mask obtained by the same method as in Example 1 was etched by wet blasting, and then the mask pattern was removed. As a result of observing this with an optical microscope, there were variations in the etching amount of the resin composition layer, and there were places where the resin composition remained on the epoxy resin glass cloth substrate. Moreover, many scratches made by blasting were confirmed on the conductor pattern in which part or all of the surface was exposed.

In Examples 1 to 21, as compared with Comparative Example 5 or Comparative Example 6, the resin composition layer does not have defects such as deformation and alteration, and scratches are not generated on the connection pads. The resin composition layer could be etched without leaving the conductive pattern on the epoxy resin glass cloth substrate without leaving a conductive composition level on the epoxy resin glass cloth substrate when the layer was etched. .

A comparison between Examples 10 and 12 to 16 and Example 1 shows that by adding an ethanolamine compound to the etching solution for the resin composition, there is no practically problematic level of resin residue or undercut. Etching time could be shortened.

In Examples 4 and 5, since the content of fused silica was reduced as compared with Example 1, the etching time was increased, but no practically problematic undercut occurred.

In Examples 6 to 8 using glass, clay, and aluminum hydroxide instead of the fused silica of Example 5, etching was possible, but the etching time was longer than that of fused silica. However, there was no level of undercut that would cause a practical problem.

In Examples 17 and 18 in which sodium hydroxide and lithium hydroxide were used instead of the potassium hydroxide of Example 1, an undercut at a level causing a practical problem did not occur.
In Example 19, compared with Example 10, since the temperature of the etching solution was increased, the etching time was shortened, but a practically problematic level resin composition remained on the epoxy resin glass cloth substrate. The resin composition layer could be etched. In Examples 20 and 21, since the temperature of the etching solution was lowered as compared with Example 10, the etching time became longer, but undercutting at a level causing a practical problem did not occur.
(Examples 22 to 28)
Etching treatment was performed in the same manner as in Example 1 except that the etching solutions listed in Table 3 were used as the etching solution.
(Example 29)
Etching was performed in the same manner as in Example 22 except that the content of fused silica was 50% by mass and the content of the biphenyl aralkyl type epoxy resin was 38% by mass.
(Examples 30 to 32)
Etching was performed in the same manner as in Example 29 except that glass, clay and aluminum hydroxide were used as the inorganic filler instead of fused silica.
(Examples 33 and 34)
Etching treatment was performed in the same manner as in Example 22 except that the etching solutions listed in Table 3 were used as the etching solution.

In Examples 22 to 34, as compared with Comparative Example 5 or Comparative Example 6, the resin composition layer does not have defects such as deformation and alteration, and scratches are not generated on the connection pads. The resin composition layer could be etched without leaving the conductive pattern on the epoxy resin glass cloth substrate without leaving a conductive composition level on the epoxy resin glass cloth substrate when the layer was etched. .

When Examples 22 to 34 and Examples 9 to 16 are compared, undercuts occur in Examples 22 to 34 using an etching solution for a resin composition containing two or more kinds of ethanolamine compounds. It was difficult.

From the comparison of Examples 22 and 25 to 28, the etching time was short in Examples 22, 25 and 26 in which the etching solution for the resin composition contained N- (β-aminoethyl) ethanolamine as the ethanolamine compound. Undercut did not occur. In Example 27 in which the etching solution for the resin composition did not contain N- (β-aminoethyl) ethanolamine as the ethanolamine compound, a small undercut occurred, and the etching solution for the resin composition was ethanol. In Example 28 which did not contain N- (β-aminoethyl) ethanolamine as the amine compound, undercut did not occur, but the etching time was long.

In Example 29, since the content of fused silica was reduced as compared with Example 22, the etching time was increased, but undercut did not occur.
In Examples 30 to 32 using glass, clay, and aluminum hydroxide instead of the fused silica of Example 29, etching was possible, but the etching time was longer than that of fused silica. However, undercut did not occur.

In Examples 33 and 34 using sodium hydroxide or lithium hydroxide instead of the potassium hydroxide of Example 22, no undercut occurred.
(Example 35)
In Example 1, a part of the resin composition layer was etched with an etching solution (treatment temperature 80 ° C.) containing 30% by mass of potassium hydroxide and 30% by mass of N- (β-aminoethyl) ethanolamine through a metal mask. Was removed (step (A)). Thereafter, the remaining resin composition layer is completely removed by a water washing removal solution (treatment temperature 20 ° C.) containing 0.3% by mass of potassium hydroxide and 0.3% by mass of N- (β-aminoethyl) ethanolamine. (Step (B)). After the step (B), the etching solution remaining on the surface of the resin composition layer was washed by spraying with pure water. Step (A) and step (B) were both performed by immersion treatment. Compared with Example 10 not including the step (B), it was confirmed that the resin composition layer was removed by etching without leaving the resin composition layer on the epoxy resin glass cloth substrate including the surface of the conductor pattern. In addition, an undercut at a level causing a practical problem was not confirmed. Tables 4 and 5 show the temperature of the etching solution and the time required for the etching process.

(Examples 36 to 46)
Etching treatment was performed in the same manner as in Example 35, except that the composition of the etching solution in step (A) and / or the water washing removal solution in step (B) was changed to the formulation shown in Table 4 and Table 5. . Comparing Examples 36 to 39 and Example 35, the time taken for the resin composition layer to be removed by etching was shortened as the content of potassium hydroxide in the etching solution increased. In addition, when Examples 40 to 46 and Example 35 were compared, the time until removal by etching was changed by changing the type of ethanolamine compound and alkali metal hydroxide in the etching solution. There was no practically problematic level of the resin composition remaining on the fabric substrate, and no undercut occurred. On the other hand, when Examples 37 and 39 were compared with Example 35, when the content of potassium hydroxide or ethanolamine compound increased, a tendency to generate minute undercuts on the bottom surface was observed, but there was no practical problem. It was a level.
(Examples 47 and 48)
Etching treatment was performed in the same manner as in Example 35 except that the content of fused silica was 65% by mass and 50% by mass, and the content of the biphenyl aralkyl type epoxy resin was 23% by mass and 38% by mass. . As the content of fused silica decreased, the time taken for all the resin composition layers to be removed by etching increased, but in both cases, the resin composition did not remain on the epoxy resin glass cloth substrate, Cut did not occur.
(Examples 49 to 51)
Etching was performed in the same manner as in Example 35 except that glass, clay, and aluminum hydroxide were used as the inorganic filler instead of fused silica. Although it took a long time to remove all the resin composition layers by etching, none of the resin compositions remained on the epoxy resin glass cloth base material, and no undercut occurred.
(Examples 52 to 58)
Etching treatment was performed in the same manner as in Example 35 except that the treatment temperature in step (A) or step (B) was changed to the temperature described in Table 4 or Table 5. Comparing Examples 52 to 54 and Example 35, the processing temperature in the step (A) was lowered. Therefore, the time taken for the resin composition layer to be removed by etching was increased. It was confirmed that the resin composition having a practically problematic level was not etched on the material and was removed by etching. In addition, an undercut at a level causing a practical problem was not confirmed. In addition, the cross-sectional shape of the resin composition layer removed by etching was at a level where there was no practical problem, although a minute undercut was observed on the bottom surface when the processing temperature in the step (A) was increased. Comparing Examples 55 to 58 and Example 35, the higher the treatment temperature in the step (B), the more the resin tends to remain on the epoxy resin glass cloth substrate. Further, no undercut occurred in the cross-sectional shape of the resin composition layer removed by etching.
(Example 59)
Etching treatment was performed in the same manner as in Example 35 except that the etching liquid described in Table 6 or 7 was used as the etching liquid. Compared with Example 22 which does not include the step (B), it was confirmed that the resin composition layer was etched away without remaining on the epoxy resin glass cloth substrate including the conductor pattern surface. In addition, an undercut at a level causing a practical problem was not confirmed. Tables 6 and 7 show the temperature of the etching solution and the time required for the etching process.

(Examples 60 to 65)
Etching treatment was performed in the same manner as in Example 59, except that the composition of the etching solution in step (A) and / or the water washing removal solution in step (B) was changed to the formulation shown in Table 6 and Table 7. . From a comparison of Examples 59 and 62 to 65, in Examples 59, 62 and 63 in which the etching solution for the resin composition contains N- (β-aminoethyl) ethanolamine as the ethanolamine compound, the etching time is short. Undercut did not occur. In Example 64 in which the etching solution for the resin composition did not contain N- (β-aminoethyl) ethanolamine as the ethanolamine compound, a small undercut occurred, and the etching solution for the resin composition was ethanol. In Example 65 not containing N- (β-aminoethyl) ethanolamine as the amine compound, undercut did not occur, but the etching time was long.
Example 66
Etching treatment was performed in the same manner as in Example 59 except that the content of fused silica was 50% by mass and the content of the biphenyl aralkyl type epoxy resin was 38% by mass. Compared with Example 59, since the content of fused silica was reduced, the etching time was longer, but no undercut occurred.
(Examples 67 to 69)
Etching was performed in the same manner as in Example 59 except that glass, clay, and aluminum hydroxide were used as the inorganic filler instead of fused silica. Although etching was possible, the etching time was longer than that of fused silica. Undercut did not occur.
(Examples 70 to 71)
Etching treatment was performed in the same manner as in Example 59 except that the etching solutions shown in Table 6 or Table 7 were used as the etching solutions. Even when sodium hydroxide or lithium hydroxide was used instead of potassium hydroxide, undercut did not occur.

The etching solution of the present invention can etch an insulating resin composition layer excellent in heat resistance, dielectric properties, mechanical strength, chemical resistance, etc. filled with a high content of inorganic filler, for example, It can be applied to fine processing of insulating resin in multilayer build-up wiring boards, component built-in module substrates, flip chip package substrates, package substrate mounting motherboards, and the like.

DESCRIPTION OF SYMBOLS 1 Circuit board 2 Insulating layer 3 Solder connection pad, connection pad 4 Resin composition layer 5 Metal mask 6 Copper foil

Claims

An etching solution for a resin composition comprising an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler, wherein the etching solution contains 15 to 45% by mass of an alkali metal hydroxide .
The etching for a resin composition according to claim 1, wherein the alkali metal hydroxide is at least one compound selected from potassium hydroxide, sodium hydroxide, and lithium hydroxide. liquid.
The etching liquid for resin composition according to claim 1 or 2, wherein the inorganic filler is at least one selected from silica, glass, clay, and aluminum hydroxide.
4. The etching solution according to claim 1, wherein the etching solution contains 5 to 40% by mass of an ethanolamine compound.
The ethanolamine compound is at least one selected from the group consisting of ethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, N-ethylethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine. The etching solution according to claim 4, wherein the etching solution is a compound.
The ethanolamine compound is at least two selected from the group consisting of ethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, N-ethylethanolamine, N-methyldiethanolamine and N-ethyldiethanolamine. It is a compound, The etching liquid for resin compositions of Claim 4 characterized by the above-mentioned.
The etching solution for a resin composition according to claim 6, comprising at least N- (β-aminoethyl) ethanolamine as the ethanolamine compound.
A method for etching a resin composition layer comprising an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler, comprising the step of removing the resin composition layer with the etching solution according to any one of claims 1 to 7. An etching method characterized by the above.
In the method for etching a resin composition layer comprising an alkali-insoluble resin and 50 to 80% by mass of an inorganic filler,
(A) a step of removing a part of the resin composition layer with the etching solution according to any one of claims 4 to 7;
(B) Resin composition layer remaining by washing and removing liquid containing alkali metal hydroxide and ethanolamine compound, the contents of which are less than the contents of alkali metal hydroxide and ethanolamine compound in the etching solution, respectively. A step of completely removing
The etching method characterized by including these in this order.
The etching method according to claim 8 or 9, wherein the step of removing the resin composition layer is an immersion treatment.