Surface modifier, metal foil with surface modified layer, and electronic device

Abstract

A surface modifier according to the present invention forms a surface modified layer between a metal layer and a resin layer. The absolute value of the amount of change in the work function of the copper plate surface before and after application when the surface modifier is applied to the copper plate is in the range of 0.15-1.00 eV.

Description

Surface modifier, metal foil with surface modification layer, and electronic device

[0001] The present invention relates to a surface modifier, a metal foil with a surface modification layer, and an electronic device. In particular, the present invention relates to a surface modifier that can prevent metal foils from sticking together during storage and can prevent scratches during transportation.

[0002] In recent years, the advancement of the data society has led to 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 a metal layer (metal foil) or 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.

[0003] Therefore, in order to improve the adhesion between a metal layer and a resin layer, a method is known in which a coating for improving adhesion to the resin layer is formed on the surface of the metal layer (see, for example, Patent Document 1).Also known is a method in which an organic coating is formed on the surface of the metal layer using a treatment liquid containing a nitrogen-containing compound having an amino group, thereby improving the adhesion between the metal layer and the resin layer (see, for example, Patent Document 2).

[0004] Due to production schedules and other factors, it may be necessary to temporarily store metal foil after roughening and cleaning. However, if metal foil is stored in a stacked or rolled state, the metal foils may stick together, causing bending or folding at the points where stress is concentrated when the metal foil is peeled off. As a result, the conformability of the resin layer (photosensitive resin film resist) formed on the metal foil deteriorates, leading to quality degradation and defects.

[0005] Therefore, the present inventors have found that by surface-treating the metal foil, it is possible to prevent the metal foil from sticking during storage. However, by surface-treating the metal foil, a problem arises in that the treated surface of the surface-treated metal foil is scratched during transportation.

[0006] JP 2017-203073 A JP 2008-274311 A

[0007] The present invention has been made in view of the above-mentioned problems and circumstances, and aims to provide a surface modifier, a metal foil with a surface modification layer, and an electronic device that can prevent metal foils from sticking to each other during storage and prevent scratches during transportation.

[0008] In order to solve the above-mentioned problems, the present inventors have investigated the causes of the above-mentioned problems. As a result, the present inventors have found that when the change in the work function of the copper plate surface before and after applying a surface modifier to the copper plate is within a specific range, it is possible to prevent scratches from occurring when the metal foils are attached to each other during storage or when the metal foils are transported. That is, the above-mentioned problems of the present invention are solved by the following means.

[0009] 1. A surface modifier that forms a surface modification layer between a metal layer and a resin layer, wherein the absolute value of the change in work function of the copper plate surface before and after application of the surface modifier to the copper plate is within the range of 0.15 to 1.00 eV.

[0010] 2. The surface modifier according to item 1, which contains a nitrogen-containing heterocyclic compound.

[0011] 3. The surface modifier according to item 2, wherein the nitrogen-containing heterocyclic compound is a compound having both a nitrogen-containing heterocycle and a functional group containing a nitrogen atom or an oxygen atom, and the number of nitrogen atoms in the nitrogen-containing heterocycle is 2 to 4, at least one of which is NH.

[0012] 4. The functional group is —COOH, —NH ２ , —OH, —NHR or —NR ２ 4. The surface modifier according to claim 3, wherein R represents an alkyl group.

[0013] 5. The surface modifier according to item 2, wherein the nitrogen-containing heterocyclic compound has a structure represented by the following general formula 1 or 2: [In the formula, W １ ~W ７ represents a carbon atom or a nitrogen atom, W １ ~W ７ Two to four of the Y represent nitrogen atoms, and at least one nitrogen atom is bonded to a hydrogen atom. １ ~Y５ represents a carbon atom or a nitrogen atom, Y １ ~Y ５ Two to four of the groups represent nitrogen atoms, and at least one nitrogen atom is bonded to a hydrogen atom. １ is -COOH, -NH ２ , —OH, —NHR or —NR ２ Represents Z. ２ is —COOH, —OH, —NHR or —NR ２ R represents an alkyl group. L represents a single bond or a linking group. １ represents an integer of 3 to 5, and n ２ represents an integer of 1 to 3.

[0014] 6. The nitrogen-containing heterocyclic compound has a structure represented by the general formula 1, and W in the general formula 1 １ ~W ７ In the case where there are two nitrogen atoms and the two nitrogen atoms are W ５ ~W ７ If in W ５ and W ７ 6. The surface modifier according to claim 5, wherein is a nitrogen atom.

[0015] 7. The nitrogen-containing heterocyclic compound has a structure represented by the general formula 2, wherein n ２ 6. The surface modifier according to item 5, wherein when is 2, L does not simultaneously represent a phenylene group.

[0016] 8. The surface modifier according to item 1, wherein the absolute value of the change in work function is within the range of 0.30 to 0.80 eV.

[0017] 9. The surface modifier according to item 1, wherein the amount of dissolved oxygen at 25 ° C. is in the range of 6.0 to 11.0 ppm by mass.

[0018] 10. The surface modifier according to claim 1, wherein when the surface modifier is applied to the surface of the metal layer, the work function of the surface of the metal layer before and after application changes to a positive value.

[0019] 11. The surface modifier according to claim 1, which contains an activator.

[0020] 12. The surface modifier according to claim 1, which contains an organic acid.

[0021] 13. A metal foil with a surface modification layer, in which a surface modification layer is formed on a metal foil, the metal foil containing at least one of gold, silver, and copper as a main component, and the surface modification layer comprising the surface modifier according to any one of items 1 to 12.

[0022] 14. An electronic device using a laminate having a surface modification layer and a resin layer on a metal layer, wherein the surface modification layer is made of the surface modifier according to any one of items 1 to 12.

[0023] The above-mentioned means of the present invention can provide a surface modifier, a metal foil with a surface modification layer, and an electronic device that can prevent metal foils from sticking together during storage and prevent scratches during transportation. The mechanism by which the effects of the present invention are exerted or acted upon is not clear, but is speculated as follows.

[0024] (Prevention of Sticking During Storage) When the change in work function before and after surface treatment with a surface modifier is small, the charge levels of the treated surface of the metal layer and the back surface of the metal layer become close. Therefore, it was inferred that sticking would occur if such surface-modified metal foils were stacked for a certain period of time. Therefore, in the present invention, the absolute value of the change in work function before and after surface treatment with a surface modifier is set within the range of 0.15 to 1.00 eV, and by increasing this change, sticking of metal foils to each other can be prevented. As a result, the force required to peel the foils when they are stuck can be reduced. Considering storage for 10 days or more, the absolute value of the change in work function must be 0.15 eV or more.

[0025] (Prevention of Scratches During Transportation) It has been found that scratches are more likely to occur during transportation when the change in work function before and after surface treatment with a surface modifier is large. Although the reason for this is unclear, it is presumed that the change in work function of the treated surface changes the charge level during transportation, making friction with the transport roller, cleaning water, drying water, etc. more likely to occur. Therefore, from the perspective of preventing scratches, the change in work function must be 1.00 eV or less.

[0026] 1. Diagram showing the process of forming a metal wiring pattern (metal-clad laminate) 2. Diagram showing the process of forming a metal wiring pattern (formation of a surface modification layer) 3. Diagram showing the process of forming a metal wiring pattern (formation of a resist layer) 4. Diagram showing the process of forming a metal wiring pattern (patterning of the resist layer) 5. Diagram showing the process of forming a metal wiring pattern (etching of the surface modification layer and metal layer) 6. Diagram showing the process of forming a metal wiring pattern (peeling off the resist layer)

[0027] 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 when the surface modifier is applied to a copper plate, the absolute value of the change in work function of the copper plate surface before and after application is within a range of 0.15 to 1.00 eV. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0028] In one embodiment of the present invention, a nitrogen-containing heterocyclic compound is preferably contained, whereby nitrogen atoms (N atoms) present in the skeletal structure of the nitrogen-containing heterocyclic compound interact with the metal of the metal layer to form coordinate bonds, thereby increasing adhesion.

[0029] Preferably, the nitrogen-containing heterocyclic compound is a compound having both a nitrogen-containing heterocycle and a functional group containing a nitrogen atom or an oxygen atom, and the number of nitrogen atoms in the nitrogen-containing heterocycle is 2 to 4, at least one of which is NH. This allows the N atom of the NH to interact with the metal in the metal layer to form a coordinate bond, thereby improving adhesion to the metal layer.

[0030] The functional group is —COOH, —NH ２ , —OH, —NHR or —NR ２ Preferably, R represents an alkyl group. This allows the functional group to form a hydrogen bond or an ionic bond with a polar group present in the resin. As a result, adhesion to the resin layer can be achieved through an interaction force stronger than π-π interactions or van der Waals forces. In particular, it is preferable that the nitrogen-containing heterocyclic compound has a structure represented by General Formula 1 or General Formula 2, in terms of improving adhesion between the metal layer and the resin layer.

[0031] The nitrogen-containing heterocyclic compound has a structure represented by the general formula 1, and W in the general formula 1 １ ~W ７ In the case where there are two nitrogen atoms and the two nitrogen atoms are W ５ ~W ７ If in W ５ and W ７ is preferably a nitrogen atom. This enhances the interaction with the metal, thereby improving the adhesion to the metal layer. In addition, the nitrogen-containing heterocyclic compound has a structure represented by the general formula 2, and in the general formula 2, n ２ When L is 2, it is preferable that L does not simultaneously represent a phenylene group, which strengthens the interaction with the metal and improves the adhesiveness to the metal layer.

[0032] It is preferable that the absolute value of the change in work function is within the range of 0.30 to 0.80 eV, since this is more effective in preventing the metal foils from sticking together during storage and preventing scratches during transportation.

[0033] A dissolved oxygen content of 6.0 to 11.0 ppm by mass at 25°C is preferable in that sufficient performance can be exhibited, and it is more effective in preventing metal foils from sticking together during storage and preventing scratches during transportation. When the dissolved oxygen content is 6.0 ppm by mass or more, the adsorption rate of nitrogen atoms to the metal layer does not become too slow, and the distribution density of the nitrogen-containing heterocyclic compound in the surface does not decrease, allowing sufficient performance to be exhibited. On the other hand, when the dissolved oxygen content is 11.0 ppm by mass or less, the dissolved oxygen content is not too high, preventing aggregation of the nitrogen-containing heterocyclic compound on the surface and allowing sufficient performance to be exhibited.

[0034] When the surface modifier is applied to the surface of the metal layer, it is preferable that the work function of the surface of the metal layer before and after application changes to a positive value, in order to prevent foreign matter from adhering to the metal layer.

[0035] The surface modifier preferably contains an activator or an organic acid, since the absolute value of the change in work function can be controlled within the above range.

[0036] The metal foil with a surface modification layer of the present invention is a metal foil with a surface modification layer formed thereon, wherein the metal foil contains at least one of gold, silver, and copper as a main component, and the surface modification layer is made of the surface modifier. This makes it possible to provide a metal foil with a surface modification layer that is prevented from sticking to other metal foils during storage and from being scratched during transportation.

[0037] The electronic device of the present invention is an electronic device using a laminate having a surface modification layer and a resin layer on a metal layer, wherein the surface modification layer is made of the surface modification agent, thereby preventing metal foils from sticking together during storage and preventing scratches during transportation.

[0038] The present invention, its components, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0039] [Summary of the Surface Modifier of the Present Invention] 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 when the surface modifier is applied to a copper plate, the absolute value of the change in work function of the copper plate surface before and after application is within the range of 0.15 to 1.00 eV. In the present invention, the "surface modifier" is prepared by adding a nitrogen-containing heterocyclic compound described below to a solvent or the like.

[0040] <Change in Work Function> When the surface modifier of the present invention is applied to a copper plate, the absolute value of the change in work function of the copper plate surface before and after application of the surface modifier is in the range of 0.15 to 1.00 eV. The absolute value of the change in work function is more preferably in the range of 0.30 to 0.80 eV, and particularly preferably in the range of 0.4 to 0.7 eV.

[0041] The work function is measured using an "air photoelectron spectroscopy instrument AC-3" (manufactured by Riken Keiki Co., Ltd.). The change in the work function is calculated as follows. (Formation of surface modified layer) The following steps A and B were carried out to form a surface modified layer. (1) Step A A copper-clad laminate (R-1766 manufactured by Panasonic Corporation) having a metal layer formed on an insulating layer was washed with hydrochloric acid using a 5% aqueous hydrochloric acid solution and a spray-type washing device, and then washed with water. After washing with water, the work function of the copper-clad laminate is measured using the air photoelectron spectroscopy instrument. This is the value of the work function of the copper plate surface before application.

[0042] (2) Step B: The prepared surface modifier was applied to the metal layer of the copper-clad laminate, which had been washed with hydrochloric acid and water, using a spray coating device, and then washed with water. After washing with water, the surface was drained with a PVA roller and dried with an air knife at 80 ° C. to form a surface-modified layer with a thickness of 5 nm. After forming the surface-modified layer, the work function of the copper-clad laminate was measured using the atmospheric photoelectron spectrometer. This was taken as the work function value of the copper plate surface after application.

[0043] Then, the difference between the work function value before application and the work function value after application obtained as described above is calculated, and this is taken as the amount of change in the work function.

[0044] The absolute value of the change in work function can be adjusted to fall within the range of 0.15 to 1.00 eV by, for example, appropriately changing the types and contents of the nitrogen-containing heterocyclic compound, activator, organic acid, etc. contained in the surface modifier. Preferred embodiments of the nitrogen-containing heterocyclic compound, activator, and organic acid are described below.

[0045] In the present invention, when the surface modifier is applied to the surface of the metal layer, it is preferable that the work function of the surface of the metal layer before and after application changes to a positive value. In this case, the metal layer to be applied is not limited to a copper plate, but may be a layer containing a metal as a main component, as described below. In this case, the work function can be measured not only on the copper-clad laminate described above, but also on any other metal layer by a similar method.

[0046] <Dissolved Oxygen Amount> The surface modifier of the present invention preferably has a dissolved oxygen amount at 25°C in the range of 6.0 to 11.0 ppm by mass, and more preferably in the range of 7.0 to 10.0 ppm by mass. The dissolved oxygen amount is measured by adding the surface modifier to a 50 ml glass container with a lid to a total volume of 30 g, closing the lid, and shaking for 5 minutes to measure the dissolved oxygen concentration (ppm by mass) of the surface modifier. The dissolved oxygen concentration is measured using a portable dissolved oxygen meter "DO-31P" manufactured by DKK-TOA. The sensor is immersed near the bottom of the surface modifier solution (the measurement liquid) for approximately 1 minute, after which the measurement value is read.

[0047] Examples of means for adjusting the amount of dissolved oxygen within the above range include degassing or aeration of the surface modifier. Specific examples of degassing include a method of reducing the pressure using a water aspirator or the like and degassing while vibrating and suctioning in an ultrasonic cleaner. Specific examples of aeration include a method of bubbling an appropriate amount of oxygen gas from an oxygen cylinder. Another method for controlling the amount of dissolved oxygen is to adjust the amount of ethanol in the surface modifier. Increasing the amount of ethanol added increases the amount of dissolved oxygen. Specifically, the amount of ethanol added is preferably within a range of 0 to 50% by mass relative to the amount of water.

[0048] Furthermore, as a means for controlling the amount of dissolved oxygen, fluctuations in the amount of dissolved oxygen can be suppressed by filling an inert gas into the sealing container of the surface modifier or during the injection process.

[0049] [Composition of Surface Modifier] The surface modifier of the present invention preferably contains a nitrogen-containing heterocyclic compound, since the N atoms present in the skeletal structure of the nitrogen-containing heterocyclic compound interact with the metal of the metal layer to form coordinate bonds, thereby increasing adhesion. Furthermore, the surface modifier preferably contains water or alcohols in terms of solubility. Furthermore, the surface modifier preferably contains an organic acid or an activator, since the absolute value of the change in work function can be controlled within the above range.

[0050] <Nitrogen-Containing Heterocyclic Compound> The nitrogen-containing heterocyclic compound is a compound having both a nitrogen-containing heterocycle and a functional group containing a nitrogen atom or an oxygen atom. Preferably, the number of nitrogen atoms in the nitrogen-containing heterocycle is 2 to 4, and at least one of the nitrogen atoms is NH.

[0051] Examples of the functional group containing a nitrogen atom or an oxygen atom include —COOH and —NH ２ , —OH, —NHR or —NR ２ The functional group is preferably any one of the following, in particular, —COOH, —NH ２ or -NR ２ In order to improve adhesion between the metal layer and the resin layer, it is preferable that the nitrogen-containing heterocyclic compound has a structure represented by the following general formula 1 or 2:

[0052]

[0053] During the ceremony, W １ ~W ７ represents a carbon atom or a nitrogen atom, W １ ~W ７ Two to four of the W groups represent nitrogen atoms, and at least one nitrogen atom is bonded to a hydrogen atom. １ ~W ７ A condensed ring is formed with Y. １ ~Y ５ represents a carbon atom or a nitrogen atom, Y １ ~Y ５ Two to four of the Y represent nitrogen atoms, and at least one nitrogen atom is bonded to a hydrogen atom. １ ~Y ５ A condensed ring is formed with Z. １ is -COOH, -NH ２ , —OH, —NHR or —NR ２ Represents Z. ２ is —COOH, —OH, —NHR or —NR ２ R represents an alkyl group. L represents a single bond or a linking group. １ represents an integer of 3 to 5, and n ２ represents an integer of 1 to 3. L represents W １ ~W７ and Y １ ~Y ５ Among these, it is preferable that the carbon atom be bonded to the alkyl group.

[0054] The linking group is composed of an atom or atomic group containing a carbon atom, a nitrogen atom, a sulfur atom, or an oxygen atom. Specific examples include -O-, -S-, -N(R)-, -CO-, -SO2-, alkylene groups (e.g., methylene, ethylene, propylene, 1,4-cyclohexylene, dodecylene, hexadecylene, 2-ethylhexylene, 2-hexyldecalene, etc.), arylene groups (e.g., phenylene, naphthylene, etc.), and combinations thereof. R represents a hydrogen atom, an alkyl group, or a cycloalkyl group.

[0055] Examples of the nitrogen-containing heterocyclic compound having the structure represented by the general formula 1 or 2 are given below, but the nitrogen-containing heterocyclic compound according to the present invention is not limited to these.

[0056]

[0057]

[0058]

[0059] The nitrogen-containing heterocyclic compound has a structure represented by the general formula 1, and W in the general formula 1 １ ~W ７ In the case where there are two nitrogen atoms and the two nitrogen atoms are W ５ ~W ７ If in W ５ and W ７ is preferably a nitrogen atom. ５ and W ６ is preferably not a nitrogen atom, and the adjacent W ６ and W ７ is preferably not a nitrogen atom. ２When L is 2, it is preferable that L does not simultaneously represent a phenylene group. Among the nitrogen-containing heterocyclic compounds, the above-mentioned exemplary compounds (8), (9), (10), (17), (18), (19) and (25) are more preferable.

[0060] The surface modifier may contain only one type of nitrogen-containing heterocyclic compound having a structure represented by General Formula 1 or General Formula 2, or two or more types of nitrogen-containing heterocyclic compounds.

[0061] The nitrogen-containing heterocyclic compound is preferably contained in the solvent in an amount of 10 to 300 ppm by mass (0.001 to 0.03% by mass) based on the total mass of the solvent from the viewpoint of film-forming properties, and more preferably in an amount of 50 to 250 ppm by mass based on the total mass of the solvent.

[0062] <Water or Alcohols> Examples of the alcohols include methanol, ethanol, and 2-propanol. Two or more of water and alcohols may be used in combination as the solvent. Specifically, the mass ratio of water to alcohols is preferably within a range of 100:0 to 50:50, and more preferably within a range of 100:0 to 75:25.

[0063] <Organic Acids> Examples of the organic acids include saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, and caproic acid; unsaturated fatty acids such as (meth)acrylic acid, crotonic acid, and isocrotonic acid; saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, and pimelic acid; unsaturated aliphatic dicarboxylic acids such as maleic acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, and cinnamic acid; oxycarboxylic acids such as glycolic acid, lactic acid, malic acid, citric acid, tartaric acid, and salicylic acid; carboxylic acids having a substituent such as β-chloropropionic acid, nicotinic acid, ascorbic acid, hydroxypivalic acid, and levulinic acid; amino acids such as glycine, glutamic acid, and aspartic acid; and organic sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid. Examples of organic acids include barbituric acid and ethylenediaminetetraacetic acid. Among these organic acids, acetic acid and citric acid are preferred.

[0064] The amount of the organic acid added is preferably an appropriate ratio within the range of 0.001 to 2.0% by mass relative to the nitrogen-containing heterocyclic compound.

[0065] <Surfactant> As the surfactant, various types of surfactants such as nonionic surfactants, cationic surfactants, anionic surfactants, and silicone surfactants can be used.

[0066] Examples of nonionic surfactants include glycerol, trimethylolpropane, trimethylolethane, and their ethoxylates and propoxylates (for example, glycerol propoxylate, glycerol ethoxylate, etc.), polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, sorbitan fatty acid esters, and the like. Examples of such an anti-aging agent include Stel, Pluronic (registered trademark) L10, L31, L61, L62, 10R5, 17R2, and 25R2 (manufactured by BASF), Tetronic 304, 701, 704, 901, 904, and 150R1 (manufactured by BASF), Solsperse 20000 (manufactured by Lubrizol Japan Co., Ltd.), NCW-101, NCW-1001, and NCW-1002 (manufactured by Wako Pure Chemical Industries, Ltd.), Paionin D-6112, D-6112-W, and D-6315 (manufactured by Takemoto Oil & Fat Co., Ltd.), Olfine E1010, and Surfynol 104, 400, and 440 (manufactured by Nissin Chemical Industry Co., Ltd.).

[0067] Specific examples of cationic surfactants include organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), (meth)acrylic acid-based (co)polymer Polyflow No. 75, No. 77, No. 90, No. 95, WS, and WS-314 (manufactured by Kyoeisha Chemical Co., Ltd.), and W001 (manufactured by Yusho Co., Ltd.).

[0068] Specific examples of anionic surfactants include W004, W005, and W017 (manufactured by Yusho Co., Ltd.), and Sandet BL (manufactured by Sanyo Chemical Industries, Ltd.). Examples of silicone surfactants include Toray Silicone DC3PA, Toray Silicone SH7PA, Toray Silicone DC11PA, Toray Silicone SH21PA, Toray Silicone SH28PA, Toray Silicone SH29PA, Toray Silicone SH30PA, and Toray Silicone SH8400 (all manufactured by Dow Corning Toray Co., Ltd.), TSF-4440, TSF-4300, TSF-4445, TSF-4460, and TSF-4452 (all manufactured by Momentive Performance Materials), KP341, KF6001, and KF6002 (all manufactured by Shin-Etsu Silicones Co., Ltd.), and BYK307, BYK323, BYK330, and BYK345 (all manufactured by BYK-Chemie Co., Ltd.). Among the surfactants, silicone surfactants and cationic surfactants (acrylic compounds) are preferred.

[0069] The content of the surfactant is preferably 0.001 to 2.0% by mass, more preferably 0.005 to 1.0% by mass, based on the nitrogen-containing heterocyclic compound. Only one type of surfactant may be used, or two or more types may be used. When two or more types of surfactants are used, the total amount is preferably within the above range.

[0070] The surface modifier may contain other components in addition to those described above, such as preservatives, stabilizers, acids, bases, and pH adjusters.

[0071] <Method for preparing surface modifier> The surface modifier can be prepared by adding the nitrogen-containing heterocyclic compound to the solvent. If necessary, the organic acid, activator, or other additives may be added. After mixing the solvent and the nitrogen-containing heterocyclic compound, etc., the degassing or aeration treatment is preferably carried out, which allows the amount of dissolved oxygen in the surface modifier to be controlled.

[0072] [Laminate] The laminate according to the present invention is a laminate in which a surface modification layer and a resin layer are sequentially provided on a metal layer, and the surface modification layer is made of the surface modifier described above.

[0073] The surface modification layer is made of the surface modifier, which allows the metal layer and the surface modification layer, and the surface modification layer and the resin layer, to interact with each other. As a result, the adhesion between the metal layer and the resin layer is improved. In particular, it is preferable that the nitrogen-containing heterocyclic compound contained in the surface modifier has a structure represented by General Formula 1 or 2, in terms of improving the adhesion between the metal layer and the resin layer.

[0074] In the laminate, the heterocycle of the nitrogen-containing heterocyclic compound is preferably oriented substantially perpendicular to the metal layer, and the functional group of the nitrogen-containing heterocyclic compound is preferably oriented substantially perpendicular to the resin layer, which allows the functional group to approach the resin layer more closely, resulting in a stronger interaction and improved adhesion.

[0075] Regarding the orientation of the nitrogen-containing heterocyclic compound, for example, quantum chemistry calculation software Gaussian 16 (manufactured by Gaussian) is used, and structural optimization is performed using B3LYP (density functional theory) in DFT calculations. Calculations are performed using SDD (Stuttgart / Dresden ECP) ​​as the basis function for copper, and 6-31G(d) is used for other elements. Then, in the Grid scan module of the software Material Science Suite manufactured by Schrödinger, the position where the copper ion becomes restabilized in the space around the ligand is set as the initial position.

[0076] The laminate can be applied to, for example, a printed circuit board (printed wiring board) or an electronic device. The printed circuit board can be formed by a method for forming a metal wiring pattern by photolithography, as described below.

[0077] The structure of the laminate will be described below. The laminate has a structure in which a surface modification layer and a resin layer are sequentially provided on a metal layer. That is, the metal layer and the surface modification layer are adjacent to each other, and the surface modification layer and the resin layer are adjacent to each other.

[0078] <Metal Layer> The metal layer is a layer containing a metal as a main component. Here, the main component refers to a component contained in an amount of 50 mass % or more.

[0079] Examples of metals that can be used for the metal layer include gold, silver, platinum, zinc, palladium, rhodium, osmium, ruthenium, iridium, copper, nickel, cobalt, iron, tin, chromium, titanium, tantalum, tungsten, indium, aluminum, lead, and molybdenum, as well as alloys thereof. Among these, gold, silver, and copper are preferred, and from the viewpoints of workability and electrical conductivity, copper or a copper alloy is preferred as the main component.

[0080] The metal layer can be formed using a metal foil, plating, or vacuum film formation. The thickness of the metal layer is not particularly limited, and may be set to a thickness corresponding to the thickness of the metal wiring pattern to be formed, for example.

[0081] In forming the metal wiring pattern, a metal-clad laminate having a metal layer formed on an insulating layer is used, and therefore the laminate preferably has an insulating layer below the metal layer. The insulating layer is not particularly limited, and a resin sheet or prepreg that is generally used as an insulating layer can be used.

[0082] The laminate having the insulating layer as described above corresponds to the laminate 6 in FIG. 3, which shows the resist layer forming step to be described later.

[0083] <Surface Modification Layer> The surface modification layer can be formed by applying the surface modifier to the surface of the metal layer and drying it. The thickness of the surface modification layer is not particularly limited, but from the viewpoint of the effects of the present invention, it is preferably in the range of 0.1 to 20 nm.

[0084] <Resin Layer> The resin layer used in the present invention is not particularly limited, and 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 UV-curable resins such as UV-curable epoxy resin and UV-curable acrylic resin. These resins may be modified with a functional group and may be reinforced with glass fiber, aramid fiber, or other fibers.

[0085] When the laminate is a printed circuit board laminate, the resin layer can be a commercially available resin film or prepreg (a sheet-like fiber impregnated with a liquid resin), and resins containing fluororesin, cyclopolyolefin resin, liquid crystal polymer, epoxy resin, phenolic resin, polyimide, bismaleimide-triazine resin, modified polyphenylene ether, or cyanate ester are preferably used. Furthermore, when the laminate forms wiring on a printed circuit board (when it is a metal wiring pattern), the resin layer can be a commercially available liquid resist or dry film resist, and ultraviolet-curable epoxy resins containing alkali-soluble resins, ultraviolet-curable acrylic resins, and polyimides are preferably used.

[0086] The method for forming a metal wiring pattern is a method for forming a metal wiring pattern by photolithography, and preferably includes a step of forming a surface modification layer between a metal layer and a resist using the surface modification agent of the present invention.

[0087] <Method for forming a metal wiring pattern> Specifically, a metal wiring pattern is formed by the following steps (A) to (F): Step (A): Acid-cleaning a metal-clad laminate having a metal layer formed on an insulating layer; Step (B): Forming a surface-modified layer on the metal layer of the metal-clad laminate using the non-photosensitive surface modifier of the present invention; Step (C): Forming a resist layer containing a photosensitive resin on the surface-modified layer; Step (D): Patterning the resist layer by exposure and development; Step (E): Etching the surface-modified layer and the metal layer through the resist layer; Step (F): Peeling the resist layer from the metal-clad laminate.

[0088] Each step will be explained with reference to FIGS.

[0089] 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 subjected to acid washing. 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. The acid washing solution is not particularly limited, and conventionally known solutions can be used. Furthermore, water washing may be performed after acid washing.

[0090] The insulating layer 1 is an insulating layer that serves as the base material for the metal wiring pattern. 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. The metal layer 2 is the same as the metal layer in the laminate.

[0091] 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. The thickness of the surface modification layer 3 is not particularly limited, but from the viewpoint of the effects of the present invention, it is preferably within the range of 0.1 to 20 nm.

[0092] Between step (B) and the next step (C), it is preferable to include a step of washing the metal-clad laminate 5 on which the surface modification layer 3 has been formed with water, whereby excess non-photosensitive surface modification agent that has not sufficiently interacted with the metal layer can be removed.

[0093] 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 includes the metal layer 2, the surface modification layer 3, and the resist layer 4, and therefore corresponds to the laminate according to the present invention.

[0094] The resist layer 4, like the resist layer of the laminate, is not particularly limited as long as it contains a photosensitive resin that can be patterned by photolithography, and can be formed by laminating a dry film resist or applying a liquid resist material.

[0095] 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 portions of the resist layer 4 are dissolved and removed using a developer, thereby achieving patterning. After development, it is preferable to wash with water. The exposure and development conditions are not particularly limited, and conventionally known conditions can be used.

[0096] In step (E), the surface modification layer 3 and the metal layer 2 are etched through the resist layer 4 (see FIG. 5 ). Specifically, wet etching using an etching solution is performed to dissolve the surface modification layer 3 and the metal layer 2 in the areas where the resist layer 4 has been removed, thereby patterning the surface modification layer 3 and the metal layer 2. The etching conditions are not particularly limited, and conventionally known conditions can be used.

[0097] In step (F), the resist layer 4 is peeled off from the metal-clad laminate 5 (see FIG. 6 ). At this time, due to the effects of the present invention, the surface modification layer 3 is easily peeled off from the resist layer 4, so the surface modification layer 3 is likely to remain on the metal layer 2 of the metal-clad laminate 5. However, the surface modification layer 3 may remain on the metal layer 2 or may be peeled off together with the resist layer 4.

[0098] 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 a conventionally known remover can be used. By the above steps, the metal wiring pattern 7 can be formed.

[0099] The method for forming a metal wiring pattern allows for the formation of a high-density, high-definition metal wiring pattern, and therefore, by attaching electronic components to the metal wiring pattern as needed, a high-density, high-definition printed circuit board (printed wiring board) can be manufactured.

[0100] <Method for forming a printed circuit board laminate> The method for forming a laminate (printed circuit board laminate) according to the present invention is a method for forming a resin layer on a metal layer, and includes a step of forming a surface-modified layer between the metal layer and the resin layer using the surface modifier of the present invention. The metal layer may be solid or patterned, and known lamination methods such as hot pressing can be used. The resin layer can be a commercially available resin film or prepreg (a sheet-like fiber impregnated with a liquid resin). Resins containing fluororesin, cyclopolyolefin resin, liquid crystal polymer, epoxy resin, phenolic resin, polyimide, bismaleimide-triazine resin, modified polyphenylene ether, or cyanate ester are preferably used. The bonding surface of the resin layer may be subjected to a surface treatment such as corona treatment or plasma treatment before lamination.

[0101] [Metal Foil with Surface Modification Layer] The metal foil with a surface modification layer of the present invention is a metal foil with a surface modification layer formed on a metal foil, wherein the metal foil is primarily composed of at least one of gold, silver, and copper, and the surface modification layer is composed of the above-mentioned surface modifier. Here, "primary component" refers to a component contained in the metal foil at 50% by mass or more. Metals other than gold, silver, or copper can be the same as those listed as metals used in the metal layer. The surface modification layer is the same as the surface modification layer of the laminate described above, and therefore its description will be omitted here.

[0102] [Electronic Device] The electronic device of the present invention is an electronic device using a laminate having a surface modification layer and a resin layer on a metal layer, wherein the surface modification layer is made of the surface modifier described above. That is, the electronic device uses the laminate described above. Examples of the electronic device include smartphones, tablet terminals, personal computers, servers, routers, communication base stations, display devices, home appliances, etc.

[0103] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

[0104] <Preparation of Surface Modifier 1> Surface modifier 1 was prepared by adding 50 ppm by mass of the exemplary compound (9), which is the nitrogen-containing heterocyclic compound, to 100% by mass of ion-exchanged water as a solvent.

[0105] <Preparation of Surface Modifiers 2 to 22> Surface modifiers 2 to 22 were prepared in the same manner as in the preparation of Surface Modifier 1, except that the type and content of the nitrogen-containing heterocyclic compound, the ratio (content) of ethanol and ion-exchanged water, the types of activator and organic acid, and whether or not aeration or degassing treatment was performed were changed as shown in Table I below. Note that the "water" in Table I below refers to ion-exchanged water.

[0106] The activators and organic acids used are as follows. The amounts (mass%) of the activators and organic acids added are the amounts added relative to the nitrogen-containing heterocyclic compound. (Activators) Silicone compound: 0.1 mass%, (BYK-345, manufactured by BYK Japan, silicone surfactant) Acrylic compound: 0.5 mass%, (Polyflow WS-314, manufactured by Kyoeisha Chemical Co., Ltd., cationic surfactant)

[0107] (Organic acid) Acetic acid: 0.05% by mass Citric acid: 0.05% by mass

[0108] Degassing and aeration were carried out as follows: (Aeration) Aeration was carried out by injecting oxygen into a prepared solution containing each compound in a solvent while bubbling the solution by adjusting the flow rate from an oxygen cylinder.

[0109] (Degassing Treatment) In the degassing treatment, a prepared solution prepared by adding each compound to a solvent was depressurized using a water aspirator or the like, and degassed while vibrating and suctioning in an ultrasonic cleaner.

[0110] <Dissolved Oxygen Amount> The amount of dissolved oxygen was measured for the surface modifier prepared above. The amount of dissolved oxygen was measured by adding the surface modifier to a 50 ml glass container with a lid to make the total volume 30 g, then closing the lid and shaking for 5 minutes, and measuring the dissolved oxygen concentration (ppm by mass) of this surface modifier. The dissolved oxygen concentration was measured using a portable dissolved oxygen meter "DO-31P" manufactured by DKK-TOA. The sensor part was immersed near the bottom of the surface modifier, which was the measurement liquid, and held for about 1 minute, after which the measurement value was read. The measured dissolved oxygen concentrations are shown in the table below.

[0111] <Change in Work Function> When the surface modifier prepared above was applied to a copper plate, the change in work function of the copper plate surface before and after application was calculated. The change in work function is shown in the table below. The work function was measured using an "air photoelectron spectroscopy instrument AC-3" (manufactured by Riken Keiki Co., Ltd.). The change in work function was calculated as follows. (Formation of Surface Modified Layer) The following steps A and B were performed to form a surface modified layer. (1) Step A A copper-clad laminate (manufactured by Panasonic Corporation, R-1766) having a metal layer formed on an insulating layer was washed with hydrochloric acid using a 5% aqueous hydrochloric acid solution and a spray-type cleaning device, and then washed with water. After washing with water, the work function of the copper-clad laminate was measured using the air photoelectron spectroscopy instrument. This was taken as the work function value of the copper plate surface before application.

[0112] (2) Step B: The prepared surface modifier was applied to the metal layer of the copper-clad laminate, which had been washed with hydrochloric acid and water, using a spray coating device, followed by water rinsing. After rinsing, the surface was drained with a PVA roller and dried with an air knife at 80 ° C to form a surface-modified layer with a thickness of 5 nm. After the surface-modified layer was formed, the work function of the copper-clad laminate was measured using the atmospheric photoelectron spectrometer. This was taken as the work function value of the copper plate surface after coating. The difference between the work function value before coating and the work function value after coating obtained as described above was then calculated, and this was taken as the change in the work function. Note that Comparative Example 1 shown in the table below is a case in which no surface modifier was applied to the copper-clad laminate.

[0113] [Evaluation] <Stickness> Copper foil (model number: CF-T8G-STD-35) manufactured by Fukuda Metal Foil & Powder Co., Ltd. was cut into 10 cm x 10 cm pieces, and the copper foil was subjected to the above-mentioned process A and process B for the amount of change in work function, thereby subjecting the copper foil to a surface modification treatment. The surface-modified copper foils were stacked and left to stand for 2 hours. Then, when peeling off one of the upper copper foils, it was visually observed whether the copper foils below lifted up. According to the following criteria, "A" and "B" were deemed acceptable for practical use. Comparative Example 1 shown in the table below is a case where no surface modifier was applied to the copper foil. (Criteria) A: Only the top copper foil was peeled off smoothly. B: The copper foil below lifted up slightly, but easily returned to its original position. C: It completely stuck to the copper foil above and lifted up at the same time.

[0114] <Occurrence of scratches during transportation> A copper-clad laminate (R-1766, manufactured by Panasonic) was subjected to process A and process B for the amount of change in work function described above, and subjected to a surface modification treatment. After horizontally transporting the substrate for 5 m in an acid treatment / soft etching device (manufactured by Fuji Kiko Co., Ltd.) with the supply of chemicals stopped, the number of scratches on the substrate surface was visually counted. In the following criteria, "A" and "B" were determined to be acceptable for practical use. Note that Comparative Example 1 shown in the table below is a case where no surface modifier was applied to the copper-clad laminate. (Criteria) A: 3 or fewer scratches visible on the entire surface B: 4 to 20 scratches visible on the entire surface C: 21 or more scratches visible on the entire surface

[0115]

[0116] As shown in the above results, when the surface modifier of the present invention is used, it is possible to prevent copper foils from sticking together during storage and from being scratched during transportation, compared to when the surface modifier of the comparative example or when no surface modifier is applied. Furthermore, when a gold foil conductive transfer foil manufactured by Murata Gold Foil was used and evaluated in the same manner as described above, it was also possible to prevent gold foils from sticking together during storage and from being scratched during transportation.

[0117] INDUSTRIAL APPLICABILITY The present invention can be used for a surface modifier, a metal foil with a surface modification layer, and an electronic device that can prevent metal foils from sticking together during storage and prevent scratches during transportation.

[0118] REFERENCE SIGNS LIST 1 insulating layer 2 metal layer 3 surface modification layer 4 resist layer 5 metal-clad laminate 6 laminate 7 metal wiring pattern

Claims

1. A surface modifier that forms a surface modification layer between a metal layer and a resin layer, wherein the absolute value of the change in work function of the copper plate surface before and after application of the surface modifier to the copper plate is within the range of 0.15 to 1.00 eV.

2. The surface modifier according to claim 1, which contains a nitrogen-containing heterocyclic compound.

3. The surface modifier according to claim 2, wherein the nitrogen-containing heterocyclic compound is a compound having both a nitrogen-containing heterocycle and a functional group containing a nitrogen atom or an oxygen atom, and the number of nitrogen atoms in the nitrogen-containing heterocycle is 2 to 4, at least one of which is NH.

4. The functional group is -COOH, -NH ２ , —OH, —NHR or —NR ２ The surface modifier according to claim 3 , wherein R represents an alkyl group.

5. The surface modifier according to claim 2, wherein the nitrogen-containing heterocyclic compound has a structure represented by the following general formula 1 or 2: [In the formula, W １ ~W ７ represents a carbon atom or a nitrogen atom; W １ ~W ７ Two to four of Y represent nitrogen atoms, and at least one of the nitrogen atoms is bonded to a hydrogen atom. １ ~Y ５ represents a carbon atom or a nitrogen atom; Y １ ~Y ５ Two to four of the groups represent nitrogen atoms, and at least one of the nitrogen atoms is bonded to a hydrogen atom. １ is -COOH, -NH ２ , —OH, —NHR or —NR ２ Represents Z. ２ is -COOH, -OH, -NHR or -NR ２ R represents an alkyl group; L represents a single bond or a linking group. １ represents an integer of 3 to 5; ２ represents an integer of 1 to 3.

6. The nitrogen-containing heterocyclic compound has a structure represented by the general formula 1, １ ~W ７ In the case where there are two nitrogen atoms and the two nitrogen atoms are W ５ ~W ７ If in, W ５ and W ７ The surface modifier according to claim 5 , wherein is a nitrogen atom.

7. The nitrogen-containing heterocyclic compound has a structure represented by the general formula 2, wherein n ２ 6. The surface modifier according to claim 5, wherein when is 2, L does not simultaneously represent a phenylene group.

8. The surface modifier according to claim 1, wherein the absolute value of the change in work function is within the range of 0.30 to 0.80 eV.

9. The surface modifier according to claim 1, wherein the amount of dissolved oxygen at 25° C. is within the range of 6.0 to 11.0 ppm by mass.

10. The surface modifier according to claim 1, wherein when the surface modifier is applied to the surface of the metal layer, the work function of the surface of the metal layer before and after application changes to a positive value.

11. The surface modifier according to claim 1, which contains an activator.

12. The surface modifier according to claim 1, which contains an organic acid.

13. A metal foil with a surface modification layer, comprising a metal foil having a surface modification layer formed thereon, the metal foil containing at least one of gold, silver and copper as a main component, and the surface modification layer comprising a surface modifier according to any one of claims 1 to 12.

14. An electronic device using a laminate having a surface modification layer and a resin layer on a metal layer, wherein the surface modification layer is made of a surface modifier according to any one of claims 1 to 12.

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