WO2019039023A1

WO2019039023A1 - Microetching agent for copper and method for producing wiring board

Info

Publication number: WO2019039023A1
Application number: PCT/JP2018/020419
Authority: WO
Inventors: 知志斉藤; 優福井
Original assignee: メック株式会社
Priority date: 2017-08-23
Filing date: 2018-05-28
Publication date: 2019-02-28
Also published as: CN111051571A; JP2019039027A; JP6333455B1; TW201912839A; KR20200043993A

Abstract

This microetching agent contains an inorganic acid, cupric ions, halide ions, and a water-soluble cationic polymer which contains a quaternary ammonium group in a side chain, while having a weight average molecular weight of 1,000 or more. The molar concentration of the halide ions is 5 to 100 times the molar concentration of the cupric ions in this microetching agent. It is preferable that the pH of this microetching agent is 2 or less. By using this microetching agent, a copper surface is able to be provided with a roughened shape that exhibits excellent adhesion to a resin and the like even if the amount of etching is low.

Description

Method of manufacturing copper micro-etching agent and wiring board

The present invention relates to a copper microetching agent and a method of manufacturing a wiring substrate.

In the manufacture of printed wiring boards, in order to improve the adhesion between a copper surface and a resin material such as a solder resist, the copper surface is roughened with a microetching agent (roughening agent). As a micro-etching agent of copper or copper alloy, an organic acid-based micro-etching agent (for example, Patent Document 1) and an inorganic acid-based micro-etching agent (for example, Patent Document 2) are known. These micro-etching agents contain an acid and an oxidizing agent, and further, halogen, polymer, ammonium salt, amines, surfactant and the like are added for the purpose of adjusting roughened shape, etching rate and the like.

WO 2014/017115 brochure WO 2007/024312 brochure

In the roughening by the micro-etching agent, the roughening progresses as the etching amount increases, so the adhesion to a resin or the like tends to be improved. On the other hand, when the copper wiring is roughened with a micro-etching agent, wire thinning may occur as the etching progresses, and problems such as high resistance and disconnection may occur. Since the influence of line thinning of the wiring becomes remarkable along with the narrowing of the wiring (fine wiring), a micro-etching agent capable of realizing high adhesion with a low etching amount is required.

The organic acid micro-etching agent of Patent Document 1 can form a roughened shape excellent in adhesion to a solder resist or the like on a copper surface even when the etching amount is 1 μm or less. However, since the organic acid-based micro-etching agent contains an organic acid, ammonium salt or the like at a high concentration, a dedicated drainage / waste solution treatment facility is required, and it can not be said that the versatility is high.

In Patent Document 2, it is described that a roughened shape excellent in adhesion to a solder resist or the like can be formed on a copper surface with an etching amount of about 1.5 μm by a hydrochloric acid-based microetching agent containing polyethyleneimine. Inorganic acid-based etchants have the advantage of easier drainage and waste liquid treatment compared to organic acid-based etchants. However, in order to ensure the adhesion to the resin using an inorganic acid-based etching agent, it is necessary to increase the etching amount as compared with the case of using an organic acid-based etching agent.

In view of the above, it is an object of the present invention to provide an inorganic acid micro-etching agent capable of forming a roughened shape excellent in adhesion to a resin or the like on a copper surface even with a low etching amount.

The present invention relates to a copper microetching agent used for surface roughening of copper. In the present specification, "copper" includes copper and copper alloys. The "copper layer" also includes a copper wiring pattern layer. The microetching agent of the present invention is an inorganic acid-based microetching agent containing an inorganic acid, cupric ion, halide ion, and a cationic polymer. The cationic polymer is a water-soluble polymer having a weight average molecular weight of 1000 or more containing a quaternary ammonium group in a side chain. The molar concentration of halide ions in the microetchant is 5 to 100 times the molar concentration of cupric ions. The pH of the microetching agent is preferably 2 or less. The weight concentration of cupric ion is preferably 50 to 2000 times the weight concentration of the polymer.

Furthermore, the present invention relates to a method of manufacturing a wiring substrate for manufacturing a wiring substrate including a copper layer. The method of manufacturing the wiring substrate includes the step of bringing the above-described micro-etching agent into contact with the copper surface to roughen it (roughening treatment step). In the roughening treatment step, a replenishing solution may be added to the microetching agent in order to keep the composition of the microetching agent in a predetermined range. The etching amount in the roughening treatment is, for example, 1 μm or less. The “etching amount” refers to the average etching amount (dissolution amount) in the depth direction, and is a value calculated from the weight, specific gravity and front projection area of the copper surface dissolved by the microetching agent. The same applies to the following “etching amount”.

According to the present invention, even with a low etching amount, a roughened shape excellent in adhesion to a resin or the like can be formed on the copper surface.

Scanning electron micrograph of a copper surface treated with solution of formulation 1. Scanning electron micrograph of a copper surface treated with solution of formulation 2. Scanning electron micrograph of copper surface treated with solution of formulation 3. Scanning electron micrograph of a copper surface treated with the solution of formulation 8. Scanning electron micrograph of copper surface treated with solution of formulation 9. FIG. 16 is a scanning electron micrograph of a copper surface treated with a solution of Formulation 10. FIG. 16 is a scanning electron micrograph of a copper surface treated with a solution of Formulation 11. Scanning electron micrograph of a copper surface treated with a solution of formulation 12. Figure 14 is a scanning electron micrograph of a copper surface treated with the solution of formulation 13. FIG. 18 is a scanning electron micrograph of a copper surface treated with a solution of Formulation 18. FIG. 18 is a scanning electron micrograph of a copper surface treated with a solution of Formulation 19. FIG. 16 is a scanning electron micrograph of a copper surface treated with a solution of formulation 20. FIG. FIG. 21 is a scanning electron micrograph of a copper surface treated with a solution of formulation 21. FIG. Fig. 24 is a scanning electron micrograph of a copper surface treated with a solution of formulation 22. Fig. 24 is a scanning electron micrograph of a copper surface treated with a solution of formulation 23. Fig. 24 is a scanning electron micrograph of a copper surface treated with a solution of formulation 24. Scanning electron micrograph of copper surface treated with solution of formulation 25. FIG. 24 is a scanning electron micrograph of a copper surface treated with a solution of Formulation 26. FIG. Scanning electron micrograph of a copper surface treated with the solution of formulation 27. The surface photograph of the test piece of evaluation result A in a solder heat resistance test. The surface photograph of the test piece of evaluation result B in a solder heat resistance test. The surface photograph of the test piece of evaluation result X in a solder heat resistance test.

[Composition of micro-etching agent]
The microetching agent of the present invention is used for surface roughening of copper. The microetching agent is an acidic aqueous solution containing inorganic acid, cupric ion, halide ion and polymer. Hereinafter, each component contained in the micro-etching agent of this invention is demonstrated.

<Copper ion>
The cupric ion acts as an oxidizing agent to oxidize copper. Sources of cupric ions to be added to the microetching agent include copper halides such as cupric chloride and cupric bromide; inorganic acid salts such as cupric sulfate and cupric nitrate; cupric formate, Organic acid salts such as cupric acetate; cupric hydroxide; cupric oxide and the like. Since cupric halide produces cupric ion and halide ion in aqueous solution, it can be used as having both the function of a halide ion source and a cupric ion source. As a cupric ion source, copper halide, cupric oxide or an inorganic acid salt is preferable. The composition in the case of coexistence of cupric oxide with a hydrohalic acid such as hydrochloric acid is equivalent to that in the case of dissolving copper halide. It is preferable that cupric oxide be readily dissolved in an acid rapidly and easily, and it is preferable that easily soluble cupric oxide used in "copper plating solution using insoluble anode" or the like be used.

0.0005 to 0.5 mol / L is preferable, 0.001 to 0.3 mol / L is more preferable, and the cupric ion concentration of the micro-etching agent is 0.005 to 0.2 mol / L or less. More preferable. By adjusting the concentration of the second copper ion, the etching rate is in an appropriate range, so that the control of the etching amount becomes easy.

<Inorganic acid>
The acid has a function of dissolving copper oxidized by cupric ion in an aqueous solution, and also has a function of pH adjustment. The pH of the microetching agent is preferably 2 or less, more preferably 1.5 or less, and still more preferably 1 or less. Even when the concentration of cupric ions in the solution increases with the progress of etching, precipitation of copper hydroxide or the like can be suppressed as long as the pH is in the above range. Therefore, the stability of a solution is high and it can form the roughening shape which is excellent in adhesiveness with resin etc. on a copper surface.

In order to keep the pH of the microetching agent low, an inorganic acid is used as the acid. Inorganic acids are less likely to be coordinated to cupric ions in aqueous solution than organic acids. Therefore, by using the inorganic acid, the action of the cupric ion in the microetching agent as an oxidizing agent can be properly maintained. As the inorganic acid, a strong acid such as a hydrohalic acid such as hydrochloric acid or hydrobromic acid, a sulfuric acid or nitric acid is preferable. The hydrohalic acid can be used as having both the function of a halide ion source and an acid. Therefore, the microetching agent of the present invention preferably contains a hydrohalic acid as the inorganic acid. Among the hydrohalic acids, hydrochloric acid (aqueous hydrogen chloride solution) is preferred. The acid may be used in combination of two or more, and a small amount of organic acid may be used in addition to the inorganic acid. The acid concentration of the microetching agent is preferably adjusted so that the pH is in the above range.

<Halide ion>
The halide ion assists copper dissolution and has a function of forming a copper layer surface with excellent adhesion. As a halide ion, a chloride ion, a bromide ion etc. can be illustrated. Among them, chloride ion is preferable from the viewpoint of uniformly forming a roughened shape excellent in adhesion. The microetching agent may contain two or more halide ions.

As a halide ion source to be added to the micro-etching agent, hydrohalic acid such as hydrochloric acid or hydrobromic acid; sodium chloride, calcium chloride, potassium chloride, ammonium chloride, potassium chloride, potassium bromide, sodium bromide, copper chloride, odor And metal salts such as copper chloride, zinc chloride, iron chloride and tin bromide. The halide ion source may be used in combination of two or more. As mentioned above, the hydrohalic acid has the action of both a halide ion source and an acid, and the copper halide has the actions of both a halide ion source and a cupric ion source.

From the viewpoint of promoting formation of a roughened shape on the copper surface, the concentration of halide ion in the microetching agent is preferably 0.005 to 10 mol / L, and more preferably 0.05 to 5 mol / L. 0.1 to 3 mol / L is more preferable. By setting the halide ion concentration in the above range, the dissolution of the cuprous ion generated by the oxidation of copper in the solution is promoted, and the formation of smut on the surface of the copper layer tends to be suppressed. As described later, the micro-etching agent contains an excess of halide ions relative to cupric ions. Therefore, the appropriate range of the halide ion concentration is set according to the cupric ion concentration.

<Polymer>
The micro-etching agent of the present invention contains a water-soluble polymer having a quaternary ammonium group in a side chain and having a weight average molecular weight of 1000 or more. The polymer, together with the halide ion, has the function of forming a roughened shape with excellent adhesion. The coexistence of the cupric ion and the halide ion with the polymer having a quaternary ammonium group in the side chain in the microetching agent makes it possible to uniformly form fine irregularities on the surface of copper. From the viewpoint of forming a uniform roughened shape, the weight average molecular weight of the polymer is preferably 2000 or more, and more preferably 3000 or more. From the viewpoint of water solubility, the weight average molecular weight of the polymer is preferably 5,000,000 or less, more preferably 2,000,000 or less. The weight average molecular weight is a value obtained by gel permeation chromatography (GPC) analysis in terms of polyethylene glycol.

As a polymer which has a quaternary ammonium group in a side chain, the polymer which has a repeating unit represented, for example by following formula (I) is mentioned.

In formula (I), R ¹ to R ³ each independently represent a chain-like or cyclic hydrocarbon group which may have a substituent, and two or more of R ¹ to R ³ are bonded to each other It may form a ring structure. R ⁴ is a hydrogen atom or a methyl group, X ¹ is a single bond or a divalent linking group, and Z ⁻ is a counter anion.

Specific examples of the polymer having a repeating unit represented by the formula (I) include quaternary ammonium salt type styrene polymers, quaternary ammonium salt type aminoalkyl (meth) acrylate polymers and the like.

The polymer having a quaternary ammonium group in the side chain is, as represented by the following formula (II), a repeating unit in which a carbon atom of the main chain and a quaternary ammonium group of the side chain form a cyclic structure You may have.

In the above formula (II), R ⁵ and R ⁶ are a chain or cyclic hydrocarbon group which may have a substituent, and R ⁵ and R ⁶ are bonded to each other to form a cyclic structure. It is also good. m is an integer of 0 to 2; Each of X ² and X ³ independently represents a single bond or a divalent linking group. As a specific example of a polymer which has a repeating unit of Formula (II), the quaternary ammonium salt type | mold diallylamine polymer obtained by superposition | polymerization of the diallyl dialkyl ammonium salt represented by Formula (IIa) is mentioned.

In the above formula (IIa), R ⁷ and R ⁸ each independently represent a hydrogen atom or a chain or cyclic hydrocarbon group which may have a substituent, and is preferably a hydrogen atom.

The side chain quaternary ammonium group may have a double bond between the nitrogen atom and the carbon atom. Counter anion Z quaternary ammonium salt ^- ^{^{^{_{^{The, Cl -, Br -, I}}}}} -, ClO 4 -, BF 4 -, CH 3 COO -, PF 6 -, HSO 4 -, C 2 H 5 SO 4 - Can be mentioned. When X ¹ to X ⁷ are divalent linking groups, specific examples thereof include a methylene group, an alkylene group having 2 to 10 carbon atoms, an arylene group, a -CONH-R- group, and a -COO-R- group However, R is a single bond, a methylene group, an alkylene group having 2 to 10 carbon atoms, or an ether group (alkyloxyalkyl group) having 2 to 10 carbon atoms, and the like.

The polymer containing a quaternary ammonium group in the side chain may be a copolymer. When the polymer is a copolymer, the copolymer may contain a repeating unit containing a quaternary ammonium group and a repeating unit not containing a quaternary ammonium group. The arrangement of repeating units in the copolymer is not particularly limited, and may be any of alternating copolymer, block copolymer and random copolymer. When the copolymer is a block copolymer or a random copolymer, the ratio of the repeating unit containing a quaternary ammonium group to the monomer unit of the whole polymer is preferably 20 mol% or more, more preferably 30 mol% or more. And 40 mol% or more is more preferable. As a repeating unit containing no quaternary ammonium group, a structure derived from (meth) acrylic acid, alkyl (meth) acrylate, aminoalkyl (meth) acrylate, (meth) acrylamide, styrene derivative, sulfur dioxide, etc. It can be mentioned.

In the above-mentioned Patent Document 2, low molecular weight polyethyleneimine is used as a polymer of the inorganic acid-based micro-etching agent, but even if low molecular weight polyethyleneimine having a molecular weight of less than 1000 is used, a coarse difference is produced at a low etching amount. It is not possible to form In the above-mentioned patent documents 1, the example using high molecular weight polyethylene imine as a polymer of organic acid system micro etching agent is indicated. The micro-etching agent of the present invention has a low pH because it mainly uses an inorganic acid as the acid. Polyethyleneimine having a cationic group in the main chain is unstable under strong acidity, and formation of a finely roughened shape is difficult. On the other hand, a cationic polymer containing a quaternary ammonium group in the side chain is stable even under strong acidity of pH 1 or less and contributes to the formation of a finely roughened shape.

The concentration of the polymer in the micro-etching agent is preferably 0.0002 to 0.2 g / L, more preferably 0.001 to 0.04 g / L, from the viewpoint of forming a copper layer surface excellent in adhesion. .004 to 0.02 g / L is more preferable. As described later, the appropriate range of the polymer concentration in the microetching agent is set according to the cupric ion concentration.

<Proportion of each component>
The micro-etching agent of the present invention is characterized in that it contains an excess of halide ion to cupric ion. The halide ion concentration (molar concentration) of the microetching agent is preferably 5 times or more of the cupric ion concentration, more preferably 7 times or more, and still more preferably 10 times or more. When the micro-etching agent contains an excessive amount of halide ion with respect to the cupric ion, a roughened shape excellent in adhesion to a resin or the like can be formed on the copper surface even with a low etching amount. From the viewpoint of forming a uniform roughened shape, the halide ion concentration is preferably 100 times or less of the cupric ion concentration, more preferably 70 times or less, and still more preferably 50 times or less.

In an etchant containing a halide ion and cupric ion as an oxidizing agent, metallic copper is oxidized and cupric ion is reduced to form cuprous ion. Since the cuprous halide such as copper (I) chloride has low solubility, insoluble smut precipitates on the copper surface. On the other hand, since one cuprous ion forms a soluble complex with the four halide ions, the cuprous halide rapidly dissolves again when the halogen is present in excess. That is, when the halogen is present in excess, the deposition of smut on the copper surface is suppressed, so that each component constituting the micro-etching agent becomes an environment in which the metal copper surface easily contacts. In such an environment, it is considered that the action of the above-mentioned cationic polymer is easily expressed, and even with a low etching amount, fine irregularities excellent in adhesion to the resin are easily formed.

From the viewpoint of enhancing the surface shape forming action by the cationic polymer, the weight concentration of cupric ion in the etching agent is preferably 50 to 2,000 times, more preferably 100 to 1,500 times, the weight concentration of the cationic polymer. 1000 times is more preferable.

<Other additives>
The micro-etching agent of the present invention can be prepared by dissolving the above-mentioned components in ion-exchanged water and the like. The microetching agent may contain components other than the above. For example, a nonionic surfactant may be added for the purpose of homogenizing the roughening. Nonionic surfactants also act as antifoam agents. In addition, various additives may be added as needed. When these additives are used, the concentration of the additive in the microetching agent is preferably about 0.0001 to 20% by weight.

[Application of micro etching agent]
The above-mentioned micro-etching agent can be widely used to roughen the copper layer surface. Fine irregularities are uniformly formed on the treated copper surface, and adhesion to a resin such as a prepreg, a plating resist, an etching resist, a solder resist, an electrodeposition resist, and a cover lay is good. Moreover, since it is also excellent in roughened copper surface solderability, it is especially useful for manufacture of various wiring boards including for pin grid array (PGA) and ball grid array (BGA). Furthermore, it is useful also for the surface treatment of a lead frame.

In particular, since the micro-etching agent of the present invention can form a surface excellent in adhesion with a low etching amount, a printed wiring board requiring fine copper wiring, fan-out wafer level package (FOWLP), LSI It is useful for adhesion improvement processing of rewiring copper layer etc., and contributes to suppression of high resistance of copper wiring and disconnection.

[Method of manufacturing wiring board]
In the manufacture of the wiring substrate, the copper surface is roughened by bringing the above-described micro-etching agent into contact with the copper surface. When manufacturing a wiring substrate including a plurality of copper layers, only one of the plurality of copper layers may be treated with the above-described microetching agent, and two or more copper layers may be treated with the above-described microetching agent. May be

In the roughening treatment, the method for bringing the copper surface into contact with the micro-etching agent is not particularly limited. For example, the method for spraying the micro-etching agent on the copper layer surface to be treated or immersing the copper layer to be treated in the micro-etching agent And the like. In the case of spraying, it is preferable that the temperature of the microetching agent be 10 to 40 ° C., and the etching be performed under the conditions of a spray pressure of 0.03 to 0.3 MPa for 5 to 120 seconds. In the case of immersion, it is preferable to set the temperature of the microetching agent to 10 to 40 ° C. and perform etching under the conditions of 5 to 120 seconds. In addition, in the case of immersion, it is preferable to blow air into the micro-etching agent by bubbling or the like in order to oxidize cuprous ions generated in the micro-etching agent by etching of copper to cupric ions . The micro-etching agent of the present invention can be easily treated with waste liquid after use, and can be treated by a simple method using, for example, neutralization with an alkali, a polymer flocculant or the like.

70 or less is preferable and, as for L ^* value of the copper surface after the roughening process by a micro etching agent, 65 or less is more preferable. The L ^* value is the lightness L ^* in the L ^* a ^* b ^* color space (JIS Z 8781-4), and is measured by the method described in the examples described later. The untreated copper foil has a metallic luster, and L ^* is about 80 to 90. In a copper foil whose surface is roughened, incident light is irregularly reflected in multiple directions, and reflection is repeatedly attenuated. Therefore, when the roughening of the copper foil progresses and a fine uneven shape is formed, the L ^* value tends to be small.

The L ^* value of the copper surface can be controlled within the above range by adjusting the compounding ratio of the micro-etching agent and the etching amount. In one embodiment of the present invention, the compounding ratio of the microetching agent and the etching amount (etching time) can be adjusted so that the L ^* value of the copper layer surface is in the above range. For example, after roughening the surface of the copper layer with a micro-etching agent, monitor the L ^* value of the surface of the copper layer after the roughening treatment and control the addition amount of the replenishing solution described later and the timing of the addition of the replenishing solution. It can also be done.

The etching amount in the roughening treatment is not particularly limited. From the viewpoint of improving adhesion to the resin, the etching amount is preferably 0.05 μm or more, and more preferably 0.1 μm or more. In the pretreatment of the solder resist coating process of a printed wiring board that requires fine wiring, etc., if the amount of etching is too large, disconnection due to complete etching of the copper layer, increase in resistance due to reduction in wiring cross section, etc. Problems may occur. Therefore, the etching amount is preferably 1 μm or less, more preferably 0.7 μm or less, and still more preferably 0.5 μm or less.

When the microetching agent is used continuously, the roughening treatment may be performed while adding the replenishing solution. By performing the roughening treatment while adding the replenishing solution, the concentration of each component in the microetching agent during treatment can be properly maintained. As the replenishing solution, an aqueous solution containing components (acid, halide ion, and the aforementioned polymer) which decrease with the progress of etching is preferable. The replenisher may include a cupric ion source such as copper oxide. The addition amount of the replenishment liquid and the timing of the addition of the replenishment liquid can be appropriately set according to the concentration management range of each component and the like. The components in the replenishing solution are the same as the components contained in the above-mentioned micro-etching agent. The concentration of each component in the replenishing solution is appropriately adjusted in accordance with the initial concentration of the micro-etching agent used for the treatment. The composition of the replenishing solution may be the same as the preparation bath (microetching solution before use).

After the roughening treatment step, the roughened surface may be washed with an acidic aqueous solution. As the acidic aqueous solution used for washing, hydrochloric acid, sulfuric acid aqueous solution, nitric acid aqueous solution or the like can be used. Hydrochloric acid is preferred because it has less influence on the roughening shape and high washability. The acid concentration of the acidic aqueous solution is preferably 0.3 to 35% by weight, and more preferably 1 to 10% by weight. The cleaning method is not particularly limited, and examples thereof include a method of spraying an acidic aqueous solution on the surface of the roughened copper layer, and a method of immersing the roughened copper layer in the acidic aqueous solution.

After the treatment with the micro-etching agent, the solution may be treated with an aqueous solution or alcohol solution of an azole to further improve the adhesion to the resin. In addition, after the treatment with the microetching agent, an oxidation treatment such as a brown oxide treatment or a black oxide treatment may be performed.

Next, examples of the present invention will be described. The present invention is not construed as being limited to the following examples.

[Preparation of micro-etching agent]
Solutions (micro-etching agents) were prepared according to the formulations shown in Tables 1-1 to 1-2. The details of the polymers A to I are as follows. These polymers were used such that the concentration in the solution was as shown in the table.

Polymer A: vinyl pyrrolidone / N, N-dimethylaminoethyl methacrylamide diethyl sulfate random copolymer having the following structure (weight average molecular weight about 800,000)

Polymer B: Diallyldimethylammonium hydrochloride-sulfur dioxide alternating copolymer having the following repeating units (weight average molecular weight about 5000)

Polymer C: Acrylamide dimethylaminoethyl acrylate methyl chloride quaternary salt copolymer (weight average molecular weight about 2 million)
Polymer D: Dimethylaminoethyl methacrylate sulfuric acid dimethyl quaternary salt polymer (weight average molecular weight about 300,000)
Polymer E: Polymer of diallyldimethylammonium chloride (weight average molecular weight about 300,000)

Polymer F: Poly (oxyethylene oxypropylene (5E.O., 5P.O.)) glycol monoether (number average molecular weight about 510)
Polymer G: polyethyleneimine (weight average molecular weight about 70,000)
Polymer H: polyethylene imine (weight average molecular weight about 300)
Polymer I: polyoxyethylene-polyoxypropylene block polymer adduct of ethylenediamine represented by the following formula

The balance of the blending components in the table is ion exchanged water. In formulation 26, formic acid (pKa = 3.75) as an organic acid is added to formulation 2, and after measuring to 1 L with ion-exchanged water, a 48% aqueous sodium hydroxide solution is added dropwise to adjust pH 3.75 (organic acid The pH was adjusted to the same as pKa). In Formulation 27, acetic acid (pKa = 4.76) as an organic acid was added to Formulation 2 and the pH was adjusted to 1 L with ion exchanged water, and then a 48% aqueous sodium hydroxide solution was added dropwise to adjust to pH 4.76. Although these solutions contain hydrochloric acid as an inorganic acid, since the organic acid salt is adjusted to a pH range in which buffer capacity is exhibited, it has substantially the same composition as the organic acid-based etching agent. The pH of each of the solutions of Formulations 1 to 25 using only the inorganic acid was 1.0 or less.

[Treatment of copper by micro etching agent]
A glass cloth epoxy resin impregnated copper clad laminate (made by Hitachi Chemical Co., Ltd., product name: MCL-E-67, 10 cm × 10 cm, thickness 0.2 mm) in which a 35 μm thick copper foil is laminated on both sides of an insulating substrate The thing which performed copper plating of was prepared as a test substrate. Next, each micro etching agent (30 ° C.) shown in Tables 1-1 to 1-5 is sprayed on the surface of the copper plating layer of the above test substrate under the condition of spray pressure of 0.10 MPa, and the etching amount of 0.5 μm The etching time was adjusted so as to be Next, the etched surface was immersed in hydrochloric acid (hydrogen chloride concentration: 3.5% by weight) at a temperature of 30 ° C. for 10 seconds, washed with water, and dried.

The surface of the copper layer of the test substrate after treatment was observed with a scanning electron microscope (SEM) (Model JSM-7000F, manufactured by Nippon Denshi Co., Ltd.). SEM observation images are shown in FIGS. The composition of each solution and the correspondence between SEM observation images are shown in Table 1-1 and Table 1-2.

<Adhesive evaluation by solder heat resistance test>
A glass cloth epoxy resin impregnated prepreg (manufactured by Hitachi Chemical Co., Ltd., product name: GEA-67N, thickness 0.1 mm) is laminated on the etched surface of the test substrate after the above drying (press pressure: 30 MPa, temperature: 170 ° C.) , Time: 60 minutes). Next, the periphery of the laminated substrate was cut off to prepare a test piece. The test piece was left in an environment of 120 ° C. (relative humidity: 100%) for 2 hours, and then immersed in a molten solder bath of 230 ° C. for 30 seconds. The test pieces after immersion were visually observed, and those which did not show any blistering were A (see FIG. 20) and those whose blistering occurred within 10% of the surface were B (see FIG. 21). And X) (see FIG. 22) where swelling occurred in a region of 10% or more of the surface. The results are shown in Tables 1-1 and 1-2. If the adhesion between the copper foil and the resin is good, no blistering is observed.

<Evaluation of roughened surface by L ^* value>
About the etching process side of the test substrate after the said drying, three places were selected arbitrarily, L ^* value was measured with a color-color-difference meter (model: CR-10) made by Konica Minolta, and the average value was computed. The results are shown in Tables 1-1 and 1-2.

From the results in Tables 1-1 and 1-2, the L ^* value of the copper surface after roughening is correlated with the solder heat resistance test results, and the smaller the L ^* value, the better the solder heat resistance, and copper It can be seen that the adhesion between the surface and the resin is good.

In formulations 1 to 3 using polymer A, the L ^* value of the copper surface after roughening was all 55 or less, and a roughened shape excellent in adhesion to the resin was formed (see FIGS. 1 to 3). ). In the formulations 1 to 3, the concentration of each component is largely different, but the molar concentration ratio of halogen to cupric ion and the weight concentration ratio of cupric ion to polymer are within the predetermined ranges, so the same roughening is achieved. It is considered that the shape is formed.

In the formulations 4 to 7, the L ^* value of the copper surface after roughening was 65 or less. On the other hand, in the formulations 13 to 17 (see FIG. 9), the L ^* value of the copper surface after roughening was larger than in the formulations 1 to 11, and the formation of the roughened shape was insufficient.

From these results, it is understood that by adjusting the compounding ratio of the halide ion, the cupric ion and the polymer, a roughened shape excellent in adhesion to the resin can be formed even with a low etching amount of about 0.5 μm.

Also in the formulations 8 to 11 (see FIGS. 4 to 7) containing the polymers B to E instead of the polymer A, the L ^* value of the copper surface after roughening was 65 or less as in the formulations 1 to 7. On the other hand, in formulation 12 (see FIG. 8) in which the polymer is not blended and formulations 20 and 21 (see FIGS. 12 and 13) in which polymer G (high molecular weight polyethyleneimine) is included, although the surface is roughened, formulation 1 The L ^* value of the copper surface after the roughening was larger than that of the sample No. 11 and the formation of the roughened shape was insufficient.

Formulations 18, 19 (see FIGS. 10 and 11) containing polymer F (nonionic surfactant containing no quaternary ammonium salt), and formulations 22 and 23 (polymer 14 containing low molecular weight polyethyleneimine) (FIG. 14) In 15, 15), the surface was hardly roughened at any polymer concentration, and showed a larger L ^* value than the formulation 12 containing no polymer. In the formulations 24, 25 using Polymer I (derivative polymer of ethylene diamine), the copper surface was not roughened at all at any polymer concentration.

From these results, when using a polymer having a quaternary ammonium group in the side chain and using an inorganic acid solution in which the compounding ratio of cupric ion, halide ion, and polymer is within a predetermined range It turns out that the fine uneven | corrugated shape excellent in adhesiveness can be formed in a copper surface.

In the solution of the organic acid system of the combination 26, 27 adjusted to the buffer pH (the same pH as the pKa of the organic acid) by adding the organic acid, the L ^* value of the copper surface after roughening is lower than that of the combination 1-11. The formation of a large, roughened shape was inadequate. One reason for the insufficient formation of the roughened shape is considered to be that the pH is high and the solubility of copper ions generated by etching is low. In addition, since the organic acid is easily coordinated to cupric ion, in the solutions of Formulation Examples 26 and 27, the effective concentration of cupric ion was lowered, and the balance between the cupric ion and the halide ion was broken. It is also considered that the roughening shape is insufficient.

Claims

A copper micro-etching agent used for surface roughening of copper,
Inorganic acids, cupric ions, halide ions, and cationic polymers,
The cationic polymer is a water-soluble polymer having a weight average molecular weight of 1000 or more and containing a quaternary ammonium group in a side chain,
The molar concentration of the halide ion is 5 to 100 times the molar concentration of the cupric ion,
Micro-etching agent whose pH is 2 or less.
The microetching agent according to claim 1, wherein the molar concentration of cupric ion is 0.001 to 0.5 mol / L.
The microetching agent according to claim 1 or 2, wherein the molar concentration of the halide ion is 0.01 to 10 mol / L.
The micro-etching agent according to any one of claims 1 to 3, wherein the concentration by weight of the polymer is 0.0005 to 0.5 g / L.
The micro-etching agent according to any one of claims 1 to 4, wherein the concentration by weight of cupric ions is 50 to 2000 times the concentration by weight of the polymer.
A method of manufacturing a wiring substrate including a copper layer,
A method of manufacturing a wiring substrate, comprising a roughening treatment step of bringing a copper surface into contact with the microetching agent according to any one of claims 1 to 5 to roughen the copper surface.
The manufacturing method of the wiring board of Claim 6 whose average etching amount of the depth direction at the time of roughening the said copper surface is 1 micrometer or less.
In the roughening treatment step, a replenisher comprising an acidic aqueous solution containing an inorganic acid, a halide ion, and a polymer is added to the micro-etching agent,
The method for producing a wiring board according to claim 6, wherein the polymer in the replenishing solution is a water-soluble polymer having a weight-average molecular weight of 1000 or more containing a quaternary ammonium group in a side chain.