JP2024077030A - Surface modifier and method for manufacturing printed wiring board - Google Patents

Abstract

To provide a surface modifier capable of further improving adhesion between a metal layer and a resin layer and to provide a method for manufacturing a printed wiring board using the surface modifier.SOLUTION: There is provided a surface modifier for forming a surface modification layer between a metal layer and a resin layer, wherein the absorbance change rate Z determined by the following expression A is within the range of 5 to 30%. Expression A: Z[%]=(X-Y)/X×100 [The absorbance of the surface modifier before application is defined as absorbance X. The absorbance of the surface modifier which is not adhered to the copper plate and becomes surplus after application to the copper plate is defined as absorbance Y. For each absorbance, the absorbance of the maximum absorption maxima within the wavelength range of 300 to 800 nm of the absorption spectrum obtained by spectrophotometry is employed.]SELECTED DRAWING: Figure 3

Description

The present invention relates to a surface modifier and a method for producing a printed wiring board.
More specifically, the present invention relates to a surface modifier capable of further improving adhesion between a metal layer and a resin layer, and a method for producing a printed wiring board using the surface modifier.

In recent years, with the advancement of the data society, there is a demand for printed wiring boards (also called "printed circuit boards") with high density and high definition wiring. In the manufacturing process of printed wiring boards, resin materials such as etching resist, plating resist, solder resist, and prepreg are bonded to the surface of the metal layer and metal wiring. In the manufacturing process of printed wiring boards and in the products after manufacture, high adhesion is required between the metal layer and the resin layer.

Conventionally, in order to increase the adhesion between the metal layer and the resin layer, the surface of the metal layer has been roughened and adhesion has been achieved through the anchor effect. However, the roughened surface of the metal layer can cause transmission loss for the short-wavelength radio waves used in communication technologies such as 5G and 6G. Therefore, there is a demand for technology that can increase the adhesion between the metal layer and the resin layer without roughening the surface of the metal layer.

The following techniques are known as methods for improving the adhesion between a metal layer and a resin layer without roughening the surface of the metal layer. Patent Document 1 discloses a method of forming an adhesion-improving coating on the surface of a metal layer to improve adhesion with a resin layer. Patent Document 2 discloses a method of improving adhesion by incorporating a sulfur-containing compound and a nitrogen-containing compound into a photosensitive resin. Patent Document 3 discloses a method of improving adhesion between metal and resin by forming an organic coating on the metal surface using a treatment liquid containing a nitrogen-containing compound with an amino group.

However, although these techniques improve the adhesion between the metal layer and the resin layer to a certain extent, sufficient adhesion has not yet been achieved.

JP 2017-203073 A JP 2020-34933 A JP 2008-274311 A

The present invention was made in consideration of the above problems and circumstances, and the problem to be solved is to provide a surface modifier that can further improve the adhesion between a metal layer and a resin layer, and a method for manufacturing a printed wiring board using the surface modifier.

In order to solve the above problems, the present inventors investigated the causes of the above problems and found that a surface modifier whose rate of change in absorbance before and after application to a metal layer is within a specific range has high performance in improving adhesion between a metal layer and a resin layer, thereby arriving at the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.

1. A surface modifier that forms a surface modification layer between a metal layer and a resin layer,
A surface modifier characterized in that a rate of change in absorbance Z calculated by the following formula A is within a range of 5 to 30%.
Formula A Z [%] = (X-Y) / X x 100
[The absorbance of the surface modifier before application is defined as absorbance X. The absorbance of the excess surface modifier that does not adhere to the copper plate after application to the copper plate is defined as absorbance Y. Each absorbance is the absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm of the absorption spectrum obtained by spectrophotometric measurement.]

2. The surface modifier according to item 1, wherein the absorbance change rate Z is within a range of 10 to 30%.

3. The surface modifier according to item 1, wherein the absorbance change rate Z is within a range of 15 to 25%.

4. Contains an adsorbent compound;
2. The surface modifier according to claim 1, wherein the adsorbent compound is a nitrogen-containing compound.

5. Contains an adsorbent compound and a solvent compound;
the adsorbent compound is a nitrogen-containing compound;
2. The surface modifier according to claim 1, wherein the solvent compound is water or an alcohol.

6. Contains an adsorbent compound and a solvent compound;
the adsorbent compound is a nitrogen-containing heterocyclic compound;
2. The surface modifier according to claim 1, wherein the solvent compound is water or an alcohol.

7. Contains an adsorbent compound and a solvent compound,
the adsorbent compound is a nitrogen-containing heterocyclic compound having at least one of a 6-5 fused ring, a 5-5 fused ring, and a 5-membered ring,
2. The surface modifier according to claim 1, wherein the solvent compound is water or an alcohol.

［一般式Ｗ中、Ｒn_１及びＲn_２は、それぞれ独立に、アルキル基を表す。Ｌは、連結基を表す。Ｗ_１～Ｗ_７は、それぞれ独立に、炭素原子又は窒素原子を表し、少なくとも２つ以上が窒素原子であり、そのうちの１つがＮＨであり、Ｗ_１～Ｗ_７で縮合環を形成する。ｍは、１以上の整数を表す。］

［一般式Ｘ中、Ｘ_１～Ｘ_５は、それぞれ独立に、窒素原子又はＣＲ_１を表す。Ｒ_１は、それぞれ独立に、水素原子、アリール基、ヘテロアリール基、アルキル基、アルケニル基、アルキニル基、アルコキシ基、アミノ基、シアノ基、チオール基、カルボニル基、ハロゲノ基、トリフルオロメチル基、又は、ヒドロキシ基を表し、さらに置換基を有していても良い。］

［一般式Ｙ中、Ｒn_１及びＲn_２は、それぞれ独立に、アルキル基を表す。Ｌは、連結基を表す。Ｙ_１～Ｙ_５は、それぞれ独立に、炭素原子又は窒素原子を表し、少なくとも２つ以上が窒素原子であり、そのうちの１つがＮＨであり、Ｙ_１～Ｙ_５で複素環を形成する。ｍは、１以上の整数を表す。］ 8. Contains an adsorbent compound and a solvent compound;
The adsorbent compound is a nitrogen-containing heterocyclic compound having a structure represented by the following general formula W, general formula X, or general formula Y:
2. The surface modifier according to claim 1, wherein the solvent compound is water or an alcohol.

[In the general formula W, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _W1 to _W7 each independently represent a carbon atom or a nitrogen atom, at least two of which are nitrogen atoms, one of which is NH, and _W1 to _W7 together form a condensed ring. m represents an integer of 1 or more.]

[In the general formula X, X ₁ to X ₅ each independently represent a nitrogen atom or CR _1. Each R ₁ independently represents a hydrogen atom, an aryl group, a heteroaryl group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a cyano group, a thiol group, a carbonyl group, a halogeno group, a trifluoromethyl group, or a hydroxyl group, and may further have a substituent.]

[In the general formula Y, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _Y1 to _Y5 each independently represent a carbon atom or a nitrogen atom, at least two of which are nitrogen atoms, one of which is NH, and _Y1 to _Y5 together form a heterocycle. m represents an integer of 1 or more.]

9. A method for manufacturing a printed wiring board, comprising the steps of:
9. A method for producing a printed wiring board, comprising the step of applying the surface modifier according to any one of claims 1 to 8 onto a metal layer to form a surface modified layer having a thickness of 15 nm or less.

10. The method for producing a printed wiring board according to claim 9, wherein the thickness of the surface modification layer is 5 nm or less.

11. The method for producing a printed wiring board according to item 9, wherein the metal layer is a layer containing copper or a copper alloy as a main component.

The above-mentioned means of the present invention can provide a surface modifier that can further improve the adhesion between a metal layer and a resin layer, and a method for manufacturing a printed wiring board using the surface modifier.

Although the mechanism by which the effects of the present invention are expressed or acted upon has not been clarified, it is speculated as follows.

In a surface modification layer formed by laminating a large amount of adsorbent compound, cohesive failure occurs within the layer, and therefore the adhesion between the metal layer and the resin layer cannot be sufficiently improved. Therefore, it is ideal for the surface modification layer to be a monolayer of the adsorbent compound. If the adsorption force of the adsorbent compound to the metal layer is too strong, too much of the compound will be laminated on the metal layer, and a monolayer or a layer close to it will not be formed. On the other hand, if the adsorption force of the adsorbent compound to the metal layer is too weak, the amount of adsorption will be too small, and the surface modification layer will not be formed sufficiently. Therefore, it is preferable that the adsorption force of the adsorbent compound contained in the surface modification agent is moderate in order to form a monolayer or a layer close to it.

Here, the surface modifier of the present invention is characterized in that the absorbance change rate Z calculated by the following formula A is within the range of 5 to 30%.
Formula A Z [%] = (X-Y) / X x 100
[The absorbance of the surface modifier before application is defined as absorbance X. The absorbance of the excess surface modifier that does not adhere to the copper plate after application to the copper plate is defined as absorbance Y. Each absorbance is the absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm of the absorption spectrum obtained by spectrophotometric measurement.]

This absorbance change rate Z is a parameter that is an index of the adsorption force of the adsorbent compound in the surface modifier. When the surface modifier is applied to a copper plate, a part of the adsorbent compound contained in the surface modifier adheres to the copper plate. Depending on the amount of the adsorbent compound adhered, the content of the adsorbent compound in the surface modifier after application decreases, and the absorbance of the surface modifier also decreases accordingly. The stronger the adsorption force of the adsorbent compound, the greater the amount of adsorption by application and the greater the decrease in absorbance, so the absorbance change rate Z of the surface modifier increases. The absorbance change rate Z of the surface modifier varies not only depending on the type of adsorbent compound, but also on the content of the adsorbent compound and other components. The inventor has found that a surface modifier that shows an absorbance change rate Z in the range of 5 to 30% has an appropriate adsorption force of the adsorbent compound. By satisfying this condition, the surface modifier of the present invention has an appropriate adsorption force of the adsorbent compound, so that it is possible to improve the adhesion between the metal layer and the resin layer to a high level.

Diagram showing the process of forming a metal wiring pattern (metal-clad laminate) A diagram showing the process of forming a metal wiring pattern (forming a surface modification layer) A diagram showing the process of forming a metal wiring pattern (forming a resist layer) A diagram showing the process of forming a metal wiring pattern (patterning of the resist layer) FIG. 1 shows a process for forming a metal wiring pattern (etching of the surface modification layer and the metal layer). A diagram showing the process of forming a metal wiring pattern (peeling off the resist layer)

The surface modifier of the present invention is a surface modifier that forms a surface modification layer between a metal layer and a resin layer, and is characterized in that the absorbance change rate Z calculated by the above formula A is within the range of 5 to 30%.
This feature is a technical feature common to or corresponding to the following embodiments.

In an embodiment of the surface modifier of the present invention, the absorbance change rate Z is preferably in the range of 10 to 30%, and more preferably in the range of 15 to 25%. This allows the amount of components contained in the surface modifier to be more appropriately adsorbed to the surface of the metal layer, making it easier to form a monolayer. This can further improve the adhesion between the metal layer and the resin layer.

In one embodiment of the surface modifier of the present invention, it is preferable that the surface modifier contains an adsorbent compound, and that the adsorbent compound is a nitrogen-containing compound.

Nitrogen-containing compounds have a high adhesion improving effect because nitrogen atoms tend to interact strongly with metal layers.

An embodiment of the surface modifier of the present invention contains an adsorbent compound and a solvent compound, and it is preferable that the adsorbent compound is a nitrogen-containing compound and the solvent compound is water or an alcohol. Water or an alcohol easily dissolves nitrogen-containing compounds.

In an embodiment of the surface modifier of the present invention, it is preferable that the surface modifier contains an adsorbent compound and a solvent compound, the adsorbent compound being a nitrogen-containing heterocyclic compound, and the solvent compound being water or an alcohol. The nitrogen-containing heterocyclic compound has a higher adhesion improving effect because the nitrogen atom is likely to interact strongly with the metal layer, and the heterocyclic structure is likely to interact strongly with the resin layer.

An embodiment of the surface modifier of the present invention contains an adsorbent compound and a solvent compound, and the adsorbent compound is preferably a nitrogen-containing heterocyclic compound having at least one of a 6-5 condensed ring, a 5-5 condensed ring, and a 5-membered ring, and the solvent compound is preferably water or an alcohol. Such nitrogen-containing heterocyclic compounds have a higher adhesion improving property.

In an embodiment of the surface modifier of the present invention, it is preferable that the surface modifier contains an adsorbent compound and a solvent compound, the adsorbent compound being a nitrogen-containing heterocyclic compound having a structure represented by the following general formula W, general formula X, or general formula Y, and the solvent compound being water or an alcohol. This allows such a nitrogen-containing heterocyclic compound to have a higher adhesion improving property.

The method for manufacturing a printed wiring board of the present invention is characterized by having a step of applying the surface modifier of the present invention onto a metal layer to form a surface modification layer having a thickness of 15 nm or less.

In an embodiment of the method for manufacturing a printed wiring board of the present invention, the thickness of the surface modification layer is preferably 5 nm or less. This can further improve the adhesion between the metal layer and the resin layer.

In an embodiment of the method for manufacturing a printed wiring board of the present invention, from the viewpoint of processability and electrical conductivity, it is preferable that the metal layer is a layer mainly composed of copper or a copper alloy.

The present invention, its components, and the forms and modes for implementing the present invention are described in detail below. Note that in this application, "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

[Overview of surface modifiers]
The surface modifier of the present invention is a surface modifier that forms a surface modified layer between a metal layer and a resin layer, and is characterized in that the absorbance change rate Z calculated by the following formula A is within the range of 5 to 30%.

Formula A Z [%] = (X-Y) / X x 100
[The absorbance of the surface modifier before application is defined as absorbance X. The absorbance of the excess surface modifier that does not adhere to the copper plate after application to the copper plate is defined as absorbance Y. Each absorbance is the absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm of the absorption spectrum obtained by spectrophotometric measurement.]

Specifically, absorbance X is the absorbance of a surface modifier in which the content of the adsorbent compound is adjusted to 20 ppm by mass. Specifically, absorbance X can be determined by the following method. First, the content of the adsorbent compound in the surface modifier is measured. If the content is less than 20 ppm by mass, the solvent is evaporated to concentrate and the content is adjusted to 20 ppm by mass. If the content is more than 20 ppm by mass, the surface modifier is diluted with ion-exchanged water regardless of the type of solvent contained in the surface modifier, and the content is adjusted to 20 ppm by mass. An absorption spectrum is obtained by spectrophotometric measurement from the surface modifier in which the content of the adsorbent compound is adjusted to 20 ppm by mass. The absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm in the absorption spectrum is taken as absorbance X.

Specifically, the absorbance Y can be determined by the following method. First, 100 mL of the surface modifier, the content of which has been adjusted to 20 ppm by mass using the above method, is applied to a 10 cm x 10 cm copper plate for 1 minute while circulating with a spray device. The spray device used is one in which the surplus surface modifier that does not adhere to the copper plate is circulated through a tank and repeatedly applied. The spray pressure for application is 0.2 MPa, and the application temperature is 25°C. After application for 1 minute, the surface modifier remaining in the tank of the spray device is removed. An absorption spectrum is obtained from the removed surface modifier by spectrophotometric measurement. The absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm in the absorption spectrum is taken as the absorbance Y.

The surface modifier of the present invention preferably has an absorbance change rate Z in the range of 10 to 30%, and more preferably in the range of 15 to 25%. This allows the components contained in the surface modifier to be more appropriately adsorbed to the surface of the metal layer, making it easier to form a monolayer. This makes it possible to further improve the adhesion between the metal layer and the resin layer.

[Surface modifier components]
The surface modifier of the present invention preferably contains at least an adsorbent compound and a solvent compound.

The adsorbent compound is a compound that can form a surface modification layer and improve the adhesion between the metal layer and the resin layer. It is preferable that the adsorbent compound adsorbs to the surface of the metal layer to form a surface modification layer. The adsorption to the surface of the metal layer is preferably chemical adsorption.

The adsorbent compound is preferably non-photosensitive. "Non-photosensitive" refers to the property of not absorbing light and not cleaving the bonds within the molecule or polymerizing the molecules together under normal conditions in the process of forming the surface modification layer.

The adsorbent compound is preferably a nitrogen-containing compound. Nitrogen-containing compounds have high adhesion improving properties because the nitrogen atoms tend to interact strongly with the metal layer.

It is more preferable that the adsorbent compound is a nitrogen-containing heterocyclic compound. Nitrogen-containing heterocyclic compounds have a higher adhesion improving effect because the nitrogen atoms tend to interact strongly with the metal layer, and the heterocyclic structure tends to interact strongly with the resin layer.

From the viewpoint of improving adhesion, it is more preferable that the adsorbent compound is a nitrogen-containing heterocyclic compound having at least one of a 6-5 condensed ring, a 5-5 condensed ring, and a 5-membered ring.

From the viewpoint of improving adhesion, the adsorbent compound is more preferably a nitrogen-containing heterocyclic compound having a structure represented by the following general formula W, general formula X, or general formula Y. Among these, it is more preferable that the adsorbent compound is a nitrogen-containing heterocyclic compound having a structure represented by the following general formula W or general formula Y.

[In the general formula W, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _W1 to _W7 each independently represent a carbon atom or a nitrogen atom, at least two of which are nitrogen atoms, one of which is NH, and _W1 to _W7 together form a condensed ring. m represents an integer of 1 or more.]

More preferably, m represents an integer from 1 to 4.

From the viewpoint of improving adhesion, it is more preferable that the nitrogen-containing heterocyclic compound having a structure represented by general formula W has a structure represented by the following general formula 1.

[In the general formula 1, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _R1 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, and may further have a substituent. _R2 represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a carboxy group, an ester group, an amide group, a heteroaryl group, or a halogeno group. Each n represents an integer of 0 to 4. m represents an integer of 1 or more. When a plurality of substituents _R2 are present, each of the substituents _R2 may be the same as or different from each other. When a plurality of n's are present, each n may be the same as or different from each other, and when a plurality of m's are present, each m may be the same as or different from each other.]

Examples of the substituent that R ₁ may have include an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a carboxy group, an ester group, an amide group, a heteroaryl group, and a halogeno group (a halogen atom).

More preferably, _R2 represents an alkyl group, an aryl group, an alkoxy group, or an aryloxy group.

More preferably, m represents an integer from 1 to 4.

From the viewpoint of improving adhesion, it is more preferable that the nitrogen-containing heterocyclic compound having the structure represented by general formula 1 has a structure represented by the following general formula 5.

[In general formula 5, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _R2 represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a carboxy group, an ester group, an amide group, a heteroaryl group, or a halogeno group (a halogen atom). Each n represents an integer of 0 to 4. m represents an integer of 1 or more. When multiple substituents _R2 are present, the respective substituents _R2 may be the same or different from each other.]

More preferably, _Rn1 and _Rn2 each represent an alkyl group having 1 to 6 carbon atoms.

More preferably, _R2 represents an alkyl group, an aryl group, an alkoxy group, or an aryloxy group.

More preferably, m represents an integer from 1 to 4.

[In the general formula X, X ₁ to X ₅ each independently represent a nitrogen atom or CR _1. Each R ₁ independently represents a hydrogen atom, an aryl group, a heteroaryl group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a cyano group, a thiol group, a carbonyl group, a halogeno group, a trifluoromethyl group, or a hydroxyl group, and may further have a substituent.]

CR ₁ preferably has an aryl group or a heteroaryl group, and more preferably the aryl group or the heteroaryl group is substituted with an alkyl group, an alkoxy group or a carbonyl group.

More preferably, X ₁ , X ₂ and X ₄ represent CR ₁ , and X ₃ and X ₅ represent a nitrogen atom.

[In the general formula Y, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _Y1 to _Y5 each independently represent a carbon atom or a nitrogen atom, at least two of which are nitrogen atoms, one of which is NH, and _Y1 to _Y5 together form a heterocycle. m represents an integer of 1 or more.]

More preferably, m represents an integer from 1 to 4.

From the viewpoint of improving adhesion, it is more preferable that the nitrogen-containing heterocyclic compound having a structure represented by general formula Y has a structure represented by the following general formulas 2 to 4.

［一般式２～４中、Ｒn_１及びＲn_２は、それぞれ独立に、アルキル基を表す。Ｌは、連結基を表す。Ｒ_１は、水素原子、アルキル基、アリール基又はヘテロアリール基を表し、さらに置換基を有してもよい。Ｒ_２は、アルキル基、アリール基、アルコキシ基、アリールオキシ基、カルボキシ基、エステル基、アミド基、ヘテロアリール基又はハロゲノ基を表す。ｎは、それぞれ０～４の整数を表す。ｍは、１以上の整数を表す。複数の置換基Ｒ_２を有する場合は、各置換基Ｒ_２は相互に同一であっても異なっていてもよい。また、複数のｎを有する場合は、それぞれのｎは相互に同一であっても異なっていてもよく、さらに、複数のｍを有する場合は、それぞれのｍは相互に同一であっても異なっていてもよい。］

[In the general formulas 2 to 4, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _R1 represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, and may further have a substituent. _R2 represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a carboxy group, an ester group, an amide group, a heteroaryl group, or a halogeno group. Each n represents an integer of 0 to 4. m represents an integer of 1 or more. When a plurality of substituents _R2 are present, each of the substituents _R2 may be the same as or different from each other. When a plurality of n's are present, each n may be the same as or different from each other, and when a plurality of m's are present, each m may be the same as or different from each other.]

Examples of the substituent that R ₁ may have include an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a carboxy group, an ester group, an amide group, a heteroaryl group, and a halogeno group (a halogen atom).

More preferably, _R2 represents an alkyl group, an aryl group, an alkoxy group, or an aryloxy group.

More preferably, m represents an integer from 1 to 4.

The following are examples of nitrogen-containing compounds. The nitrogen-containing compounds of the present invention are not limited to these.

The surface modifier of the present invention may contain only one type of adsorbent compound or two or more types of adsorbent compounds.

From the viewpoint of solubility, the surface modifier of the present invention preferably contains at least water or an alcohol as a solvent compound. The water is not particularly limited, but from the viewpoint of reducing the content of impurities, ion-exchanged water, distilled water, pure water, etc. are preferable. Examples of alcohols include methanol, ethanol, 2-propanol, etc. Two or more types of water or alcohols may be used in combination as the solvent compound.

The mass ratio of water to alcohol is preferably within the range of 100:0 to 50:50, and more preferably within the range of 100:0 to 75:25. This makes it easier to form a monolayer of the adsorbent compound.

The concentration of the adsorbent compound is preferably in the range of 0.001 to 0.01% by mass, more preferably in the range of 0.001 to 0.004% by mass, and even more preferably in the range of 0.001 to 0.002% by mass, relative to the total surface modifier. This makes it easier to form a monolayer of the adsorbent compound.

The surface modifier may contain components other than those mentioned above. Other components include surfactants, preservatives, stabilizers, acids, bases, pH adjusters, etc.

The magnesium ion concentration of the surface modifier is preferably 5 ppm by mass or less. The sulfide ion concentration of the surface modifier is preferably 5 ppm by mass or less. This prevents the adsorbent compound from reacting with magnesium ions or sulfide ions, which makes it difficult for the adsorbent compound to react with the metal layer.

[Method of manufacturing a printed wiring board]
The surface modifier of the present invention can be used in the manufacture of printed wiring boards. Specifically, in the manufacture of printed wiring boards, it can be used when adhering an etching resist (resin layer) for forming a metal wiring pattern to a metal plate (metal layer) before pattern formation. In addition, in the manufacture of printed wiring boards, it can be used when adhering a resin sheet (resin layer) such as a resin film or prepreg to a metal plate (metal layer) that may or may not be patterned.

One embodiment of the method for producing a printed wiring board of the present invention includes a step of applying the surface modifier of the present invention onto a metal layer to form a surface modification layer. One embodiment of the method for producing a printed wiring board of the present invention further includes a step of forming a resin layer on the formed surface modification layer.

Metals that can be used in the metal layer include, for example, gold, silver, platinum, zinc, palladium, rhodium, osmium, ruthenium, iridium, copper, nickel, cobalt, iron, tin, chromium, titanium, tantalum, tungsten, indium, aluminum, lead, molybdenum, and other metals, or alloys thereof. Among these, from the viewpoint of workability and electrical conductivity, it is preferable to use copper or a copper alloy as the main component. "Main component" refers to a component that is contained in an amount of 50% by mass or more.

The metal layer can be formed using metal foil, plating, or vacuum deposition.

The thickness of the metal layer is not particularly limited, and may be, for example, a thickness that corresponds to the thickness of the metal wiring pattern to be formed.

In the method for producing a printed wiring board of the present invention, the metal layer to which the surface modifier is applied may be the metal layer of a metal-clad laminate in which a metal layer is formed on an insulating layer. In this case, the insulating layer of the metal-clad laminate is, for example, a resin sheet or a prepreg.

The surface modification layer can be formed by applying the surface modification agent of the present invention onto a metal layer and drying it.

The thickness of the surface modification layer is not particularly limited, but from the viewpoint of improving adhesion, it is preferably 15 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less.

The resin contained in the resin layer is not particularly limited, but examples thereof include thermoplastic resins such as acrylonitrile/styrene copolymer resin (AS resin), acrylonitrile/butadiene/styrene copolymer resin (ABS resin), fluororesin, polyamide, polyethylene, polyethylene terephthalate, polyvinylidene chloride, polyvinyl chloride, polycarbonate, polystyrene, polysulfone, polypropylene, cyclopolyolefin resin, and liquid crystal polymer, thermosetting resins such as epoxy resin, phenolic resin, polyimide, polyurethane, bismaleimide-triazine resin, modified polyphenylene ether, and cyanate ester, and ultraviolet-curing resins such as ultraviolet-curing epoxy resin and ultraviolet-curing acrylic resin. These resins may be modified with functional groups and may be reinforced with glass fibers, aramid fibers, and other fibers.

When the resin layer is an etching resist, for example, an ultraviolet-curable epoxy resin containing an alkali-soluble resin, an ultraviolet-curable acrylic resin, or a polyimide is preferably used. The etching resist is not particularly limited as long as it contains a photosensitive resin that can be patterned by photolithography. The etching resist may be a dry film resist or a liquid resist. The etching resist may be either a negative type in which the part exposed to light forms a pattern, or a positive type in which the part not exposed to light forms a pattern.

When the resin layer is a resin film or prepreg, for example, resins containing fluororesin, cyclopolyolefin resin, liquid crystal polymer, epoxy resin, phenolic resin, polyimide, bismaleimide-triazine resin, modified polyphenylene ether, and cyanate ester are preferably used.

Below is an example of a method for forming a metal wiring pattern using the surface modifier of the present invention.

In the manufacture of a printed wiring board, for example, a metal wiring pattern can be formed by the following steps (A) to (F).
Step (A): A step of acid-washing a metal-clad laminate having a metal layer formed on an insulating layer. Step (B): A step of forming a surface-modified layer on the metal layer of the metal-clad laminate using the surface modifier of the present invention. Step (C): A step of forming a resist layer containing a photosensitive resin on the surface-modified layer. Step (D): A step of patterning the resist layer by exposure and development. Step (E): A step of etching the surface-modified layer and the metal layer through the resist layer. Step (F): A step of peeling off the resist layer from the metal-clad laminate.

Each step will be explained using Figures 1 to 6.

In step (A), a metal-clad laminate 5 (see FIG. 1), in which a metal layer 2 is formed on an insulating layer 1, is acid-washed. This removes dirt, antioxidants, oxide films, and other substances adhering to the metal surface that inhibit the interaction between the surface modifier and the metal layer. There are no particular limitations on the acid washing solution, and any conventionally known solution can be used. In addition, water washing may be performed after the acid washing.

The insulating layer 1 is an insulating layer that serves as the base material of the printed wiring board. The insulating layer 1 is made of an insulating material such as resin, and may be a prepreg in which a base material such as paper or glass is impregnated with resin.

In step (B), the surface modification layer 3 is formed on the metal layer 2 of the metal-clad laminate 5 using the surface modification agent of the present invention (see FIG. 2). Specifically, the surface modification agent is applied onto the metal layer 2 to form the surface modification layer 3.

Between step (B) and the next step (C), it is preferable to have a step of washing the metal-clad laminate 5 on which the surface modification layer 3 has been formed with water. This makes it possible to remove excess surface modification agent that has not sufficiently interacted with the metal layer.

In step (C), a resist layer 4 containing a photosensitive resin is formed on the surface modification layer 3 (see FIG. 3). The laminate 6 in this state comprises the metal layer 2, the surface modification layer 3, and the resist layer 4.

The above-mentioned etching resist can be used for the resist layer 4. The resist layer 4 can be formed by laminating a dry film resist or applying a liquid resist material.

In step (D), the resist layer 4 is patterned by exposure and development (see FIG. 4). Specifically, the resist layer 4 is exposed using a photomask that can expose the resist layer 4 in any pattern, and then unnecessary parts of the resist layer 4 are dissolved and removed using a developer, thereby patterning the resist layer 4. It is preferable to wash the resist layer 4 with water after development.

The exposure and development conditions are not particularly limited, and conventionally known conditions can be used.

In step (E), the surface modification layer 3 and the metal layer 2 are etched through the resist layer 4 (see FIG. 5). Specifically, the surface modification layer 3 and the metal layer 2 are patterned by dissolving the surface modification layer 3 and the metal layer 2 in the portion where the resist layer 4 has been removed by wet etching using an etching solution.

The etching conditions are not particularly limited, and conventionally known conditions can be applied.

In step (F), the resist layer 4 is peeled off from the metal-clad laminate 5 (see FIG. 6). At this time, the surface modification layer 3 may remain on the metal layer 2, or may be peeled off together with the resist layer 4.

The method for removing the resist layer 4 is not particularly limited, but it is preferable to remove it using a remover. The remover is not particularly limited, and any conventionally known remover can be used.

The above steps allow the metal wiring pattern 7 to be formed.

In this method for forming a metal wiring pattern, the surface modifier of the present invention, which has a high adhesion improving effect, is used, thereby achieving high adhesion between the metal layer and the resist layer in step (E). This makes it possible to prevent the etching solution from penetrating between the metal layer and the resist layer, making it possible to form a high-density, high-definition metal wiring pattern. Therefore, by attaching electronic components as required to a printed wiring board having the metal wiring pattern, it becomes possible to manufacture a high-density, high-definition printed circuit board.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

<Preparation of Surface Modifier>
A solvent was prepared by mixing ion-exchanged water and ethanol in the mass ratio shown in Table I. To this solvent, an adsorbent compound shown in Table I was added so that the content was 0.002 mass% (20 mass ppm). In this way, each surface modifier (Inventions 1 to 16, Comparative Examples 1 to 6) was prepared. The structure of the adsorbent compound is as shown below.

The magnesium ion concentration, pH, and sulfide ion concentration of each surface modifier were measured according to the industrial water testing method of JIS K 0101. The measurement results are shown in Table I.

<Formation of metal wiring pattern (no washing treatment after application of surface modifier)>
The following steps (A) to (F) were carried out to form a metal wiring pattern.

[Step (A)]
A 10 cm x 10 cm copper-clad laminate (R-1766 manufactured by Panasonic Corporation) having a metal layer formed on an insulating layer was subjected to acid cleaning. For the acid cleaning, an acid cleaning solution (CP-30 manufactured by Sanwa Chemical Industry Co., Ltd.) and a spray-type cleaning device were used. The copper-clad laminate was then washed with water.

[Step (B)]
100 mL of the surface modifier was applied for 1 minute on the metal layer of the copper-clad laminate that had been acid-washed and washed with water, while circulating it with a spray device. This spray device is designed so that the excess surface modifier that did not adhere to the copper-clad laminate is circulated through a tank and repeatedly applied. The spray pressure for application was 0.2 MPa, and the application temperature was 25°C. After application of the surface modifier, the metal layer was drained with a PVA roller without washing with water, and dried with an air knife at 80°C to form a surface-modified layer.

In order to determine the absorbance change rate Z, the absorbance X and absorbance Y of the surface modifier were measured before and after step (B). First, the absorbance X of the surface modifier was measured before application. After application, the surface modifier remaining in the tank of the spray device was removed, and the absorbance Y of the surface modifier was measured. Each absorbance was the absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm of the absorption spectrum obtained by spectrophotometric measurement. A spectrophotometer U-3900H (manufactured by Hitachi High-Tech Corporation) was used for the spectrophotometric measurement. The absorbance change rate Z calculated from the measured absorbance X and absorbance Y using the following formula A is as shown in Table I.
Formula A Z [%] = (X-Y) / X x 100

[Step (C)]
A dry film resist (AK-4034 manufactured by Asahi Kasei Corporation) was laminated on the formed surface modified layer by a hot roll laminator to form a resist layer. The lamination conditions were a roll temperature of 105°C, an air pressure of 0.35 MPa, and a lamination speed of 1.5 m/min. The dry film resist used had a support made of a polyethylene terephthalate film on one side and a protective layer made of a polyethylene film on the other side. The lamination was performed by peeling off the protective layer while adhering the surface where the protective layer was located to the metal layer via the surface modified layer.

[Step (D)]
The resist layer was exposed to light using a parallel light exposure machine (Oak HMW-801) using a chrome glass mask. The exposure conditions were 60 mj/cm ² , which is the recommended condition for dry film resist. The mask pattern used was one that formed 100 lines with a line/space of 50 μm/50 μm. The support was peeled off from the resist layer after exposure. Then, using a developer consisting of an aqueous solution of 1 mass % sodium carbonate (Na ₂ CO ₃ ) and an alkali developer, the unexposed portion of the resist layer was dissolved and removed under conditions of 30° C. Next, the resist layer was washed with water and developed. The resist layer was patterned by the above operations.

[Step (E)]
The surface modification layer and the metal layer were etched by a dipping method under conditions of a temperature of 30° C. and a dipping time of 1 minute. An aqueous solution of 2 mass % hydrochloric acid (HCl) and 2 mass % ferric chloride (FeCl ₃ ) was used as the etching solution.

[Step (F)]
The resist layer was stripped from the copper-clad laminate at 50° C. using a stripping solution consisting of an aqueous solution of 3 mass % sodium hydroxide (NaOH).

<Formation of metal wiring pattern (with water washing treatment after application of surface modifier)>
Metal wiring patterns were formed using selected ones of the prepared surface modifiers in the same manner as in the above steps (A) to (F), except that only step (B) was changed as follows.

In step (B), the process was carried out in the same manner as above up to the application of the surface modifier. After the application of the surface modifier, water was applied for 50 seconds using a spray device as a water rinsing treatment. The spray pressure for applying water was 0.2 MPa, and the application temperature was 25°C.

Then, the metal layer was drained with a PVA roller and dried with an air knife at 80°C to form a surface-modified layer. The thickness of this surface-modified layer was as shown in Table II.

<Resist adhesion>
The formed metal wiring pattern was observed under a microscope, and the resist adhesion was evaluated according to the following criteria. The higher the resist adhesion, the more the etching solution can be prevented from penetrating between the metal layer and the resist layer, and the higher the remaining rate of the metal wiring. The evaluation results are shown in Table II.
AA: The remaining rate of the metal wiring is 99% or more.
A: The remaining rate of the metal wiring is 97% or more and less than 99%.
B: The remaining rate of the metal wiring is 95% or more and less than 97%.
C: The remaining rate of the metal wiring is less than 95%.

<Adhesion variation>
Ten metal wiring patterns were formed in the same manner, and the resist adhesion of each was evaluated. Based on the evaluation results of the ten resist adhesions, the adhesion variation was evaluated according to the following criteria. The evaluation results are shown in Table II.
A: The evaluation results are the same for all 10 pieces.
B: One out of ten had a different evaluation result.
C: Two or more out of 10 have different evaluation results.

These results confirm that the surface modifier of the present invention can further improve the adhesion between the metal layer and the resin layer compared to the surface modifier of the comparative example.

1 Insulating layer 2 Metal layer 3 Surface modification layer 4 Resist layer 5 Metal-clad laminate 6 Laminate 7 Metal wiring pattern

Claims (11)

A surface modifier that forms a surface modification layer between a metal layer and a resin layer,
A surface modifier characterized in that a rate of change in absorbance Z calculated by the following formula A is within a range of 5 to 30%.
Formula A Z [%] = (X-Y) / X x 100
[The absorbance of the surface modifier before application is defined as absorbance X. The absorbance of the excess surface modifier that does not adhere to the copper plate after application to the copper plate is defined as absorbance Y. Each absorbance is the absorbance of the maximum absorption maximum in the wavelength range of 300 to 800 nm of the absorption spectrum obtained by spectrophotometric measurement.] 2. The surface modifier according to claim 1, wherein the absorbance change rate Z is within a range of 10 to 30%. 2. The surface modifier according to claim 1, wherein the absorbance change rate Z is within a range of 15 to 25%. containing an adsorbent compound,
The surface modifier of claim 1 , wherein the adsorbent compound is a nitrogen-containing compound. comprising an adsorbent compound and a solvent compound;
the adsorbent compound is a nitrogen-containing compound;
The surface modifier according to claim 1 , wherein the solvent compound is water or an alcohol. comprising an adsorbent compound and a solvent compound;
the adsorbent compound is a nitrogen-containing heterocyclic compound;
The surface modifier according to claim 1 , wherein the solvent compound is water or an alcohol. comprising an adsorbent compound and a solvent compound;
the adsorbent compound is a nitrogen-containing heterocyclic compound having at least one of a 6-5 fused ring, a 5-5 fused ring, and a 5-membered ring,
The surface modifier according to claim 1 , wherein the solvent compound is water or an alcohol. comprising an adsorbent compound and a solvent compound;
The adsorbent compound is a nitrogen-containing heterocyclic compound having a structure represented by the following general formula W, general formula X, or general formula Y:
The surface modifier according to claim 1 , wherein the solvent compound is water or an alcohol.

[In the general formula W, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _W1 to _W7 each independently represent a carbon atom or a nitrogen atom, at least two of which are nitrogen atoms, one of which is NH, and _W1 to _W7 together form a condensed ring. m represents an integer of 1 or more.]

[In the general formula X, X ₁ to X ₅ each independently represent a nitrogen atom or CR _1. Each R ₁ independently represents a hydrogen atom, an aryl group, a heteroaryl group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an amino group, a cyano group, a thiol group, a carbonyl group, a halogeno group, a trifluoromethyl group, or a hydroxyl group, and may further have a substituent.]

[In the general formula Y, _Rn1 and _Rn2 each independently represent an alkyl group. L represents a linking group. _Y1 to _Y5 each independently represent a carbon atom or a nitrogen atom, at least two of which are nitrogen atoms, one of which is NH, and _Y1 to _Y5 together form a heterocycle. m represents an integer of 1 or more.] A method for manufacturing a printed wiring board, comprising the steps of:
A method for producing a printed wiring board, comprising the step of applying the surface modifier according to any one of claims 1 to 8 onto a metal layer to form a surface modified layer having a thickness of 15 nm or less. The method for producing a printed wiring board according to claim 9, wherein the surface modification layer has a thickness of 5 nm or less. The method for producing a printed wiring board according to claim 9, wherein the metal layer is a layer containing copper or a copper alloy as a main component.

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