ELECTROLESS COPPER PLATING DEPOSIT, ELECTROLESS COPPER PLATING BATH, AND METHOD OF PRODUCING ELECTROLESS COPPER PLATING DEPOSIT
Provided are an electroless copper plating deposit that allows a metal oxide layer to exhibit good peel strength to a glass or ceramic material, and an electroless copper plating bath and a method of producing an electroless copper plating deposit, which are capable of producing the electroless copper plating deposit. Included is an electroless copper plating deposit which is formed on a metal oxide layer formed on a surface of a glass or ceramic material and which has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
The present invention relates to an electroless copper plating deposit, an electroless copper plating bath, and a method of producing an electroless copper plating deposit.
BACKGROUND ARTThe fundamental materials of conventional substrates known as printed circuit boards or package substrates mainly include materials in which resin and glass cloth are mixed. When forming a circuit on a conventional material by electrolytic copper plating, an electroless copper plating process has been used to form a base deposit.
The increase in the communication speed of electronic devices has led to an increased densification in the fields of printed circuit boards and package substrates. Thus, the level of various specification requirements, such as warpage, coefficient of thermal expansion, smoothness, dielectric constant, and cost, has been increasing. Since high-speed communication uses high frequencies, substrate smoothness is important. Therefore, glass or ceramic materials with excellent smoothness have been increasingly used as the fundamental materials of substrates, instead of conventional mixed resin/glass cloth materials.
For example, Patent Literature 1 discloses a plating deposit production method as a plating technique for materials on which a seed layer is difficult to form by typical plating techniques, such as glass and ceramic materials, particularly a glass material substrates, and describes that the method can produce a plating deposit with good adhesion to a glass substrate. The method includes a step (1) of forming a metal oxide layer on a surface of a glass substrate; a step (2) of performing a first heat treatment after the step (1); a step (3) of forming an electroless copper plating deposit on the metal oxide layer after the step (2); a step (4) of performing a second heat treatment after the step (3); and a step (5) of forming an electrolytic copper plating deposit on the electroless copper plating deposit after the step (4).
CITATION LIST Patent Literature
- Patent Literature 1: JP 2024-155434 A
The studies of the present inventors revealed that the conventional techniques still have room for improvement in terms of allowing a metal oxide layer to have good peel strength to a glass or ceramic material.
The present invention aims to solve the issue newly found by the present inventors and provide an electroless copper plating deposit that allows a metal oxide layer to exhibit good peel strength to a glass or ceramic material, particularly a glass material, and an electroless copper plating bath and a method of producing an electroless copper plating deposit, which are capable of producing the electroless copper plating deposit.
Solution to ProblemEmbodiment (1) of the present invention relates to an electroless copper plating deposit, formed on a metal oxide layer formed on a surface of a glass or ceramic material, the electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
Embodiment (2) of the present invention relates to the electroless copper plating deposit according to Embodiment (1),
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- wherein the combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium is 1.1% by mass or more.
Embodiment (3) of the present invention relates to the electroless copper plating deposit according to Embodiment (1),
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- wherein the combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium is 1.1 to 4.0% by mass.
Embodiment (4) of the present invention relates to an electroless copper plating bath, having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1 mmol/l or more.
Embodiment (5) of the present invention relates to the electroless copper plating bath according to Embodiment (4), for use in forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material.
Embodiment (6) of the present invention relates to the electroless copper plating bath according to Embodiment (4), for use in forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material, the electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
Embodiment (7) of the present invention relates to a method of producing an electroless copper plating deposit, including forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material using the electroless copper plating bath according to any one of Embodiments (4) to (6).
Embodiment (8) of the present invention relates to the method of producing an electroless copper plating deposit according to Embodiment (7),
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- wherein the electroless copper plating deposit has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
An electroless copper plating deposit according to the present invention is formed on a metal oxide layer formed on a surface of a glass or ceramic material and has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more. Such an electroless copper plating deposit allows a metal oxide layer to exhibit good peel strength to a glass or ceramic material, particularly a glass material.
An electroless copper plating bath according to the present invention has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1 mmol/l or more. Such an electroless copper plating bath is capable of producing an electroless copper plating deposit that allows a metal oxide layer to exhibit good peel strength to a glass or ceramic material, particularly a glass material.
A method of producing an electroless copper plating deposit according to the present invention includes forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material using the above electroless copper plating bath. Such a method is capable of producing an electroless copper plating deposit that allows a metal oxide layer to exhibit good peel strength to a glass or ceramic material, particularly a glass material.
An electroless copper plating deposit according to the present invention is an electroless copper plating deposit which is formed on a metal oxide layer formed on a surface of a glass or ceramic material and which has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more. Such an electroless copper plating deposit allows a metal oxide layer to exhibit good peel strength to a glass or ceramic material, particularly a glass material. Therefore, no barrier plating deposit is required between the metal oxide layer and the electroless copper plating deposit, thereby making it possible to reduce the number of steps and cost.
The electroless copper plating deposit provides the above-described advantageous effect presumably due to the following reason.
The metals in the electroless copper plating deposit, including nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and/or vanadium, may diffuse to be present not only in the electroless copper plating deposit but also in the metal oxide layer. This allows the metal oxide layer to exhibit good peel strength to a glass or ceramic material, particularly a glass material.
Herein, the term “surface of a glass material (substrate)” refers to the top of the glass material (substrate). This applies to other similar terms, such as “surface of a metal oxide layer” which means the top of the metal oxide layer.
<Glass Material (Substrate)>Non-limiting examples of usable glass materials include soda glass, soda-lime glass, alkali-free glass, and quartz glass. The glass material is preferably a glass substrate.
Non-limiting examples of usable glass substrates include known glass substrates used as circuit substrates for various electronic devices. For example, the glass substrate used is preferably a glass substrate that can be used to form traces and to produce electronic devices with increasingly higher communication speeds.
The glass substrate may be an amorphous substrate including a silica network and may contain a network former (network-forming oxide) of aluminum, boron, phosphorus, or the like, or a network modifier (network-modifying oxide) of an alkali metal, an alkaline-earth metal, magnesium, or the like.
Specific examples of the glass constituting the glass substrate include soda glass, soda-lime glass, alkali-free glass, and quartz glass. The glass may also preferably be glass such as aluminosilicate glass which may be used as tempered glass.
The amount of glass based on 100% by mass of the glass substrate is preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, and may be 100% by mass. With the above amount, the advantageous effect tends to be more suitably achieved.
Herein, the amount of glass in the glass substrate is measured using an inductively coupled plasma (ICP) emission spectrometer and calculated as the corresponding oxide.
The thickness of the glass substrate is not limited and may be appropriately selected depending on the purpose. Usually, the thickness is about 200 to 1000 μm.
<Ceramic Material (Substrate)>Non-limiting examples of usable ceramic materials include aluminum oxide (alumina) and aluminum nitride. The ceramic material is preferably a ceramic substrate.
Non-limiting examples of usable ceramic substrates include alumina substrates formed from aluminum oxide (alumina) and aluminum nitride substrates formed from aluminum nitride.
The thickness of the ceramic substrate is not limited and may be appropriately selected depending on the purpose. Usually, the thickness is about 200 to 1000 μm.
Although a glass or ceramic material is used in the present invention, a glass material is preferred to more suitably achieve the advantageous effect of the present invention. In the present invention, the glass or ceramic material is preferably a glass or ceramic substrate. An exemplary embodiment of the present invention with a glass or ceramic substrate will be described below although the present invention is not limited to the embodiment with a glass or ceramic substrate.
<Metal Oxide Layer>A metal oxide layer may be formed on a surface of a glass or ceramic substrate to serve as an intermediate layer between the glass or ceramic material and an electroless copper plating deposit, thereby easily improving the adhesion between the glass or ceramic material and the electroless copper plating deposit.
The metal oxide is preferably a zinc-containing oxide, and examples thereof include zinc oxide and oxides of alloys containing zinc and at least one metal selected from the group consisting of titanium, aluminum, silicon, tin, zirconium, nickel, indium, vanadium, chromium, iron, manganese, cobalt, and copper. Each of these may be used alone, or two or more of these may be used in combination. Preferred among these are zinc oxide and oxides of alloys containing zinc and at least one metal selected from the group consisting of indium, titanium, silicon, tin, manganese, and cobalt, with zinc oxide being more preferred.
The thickness of the metal oxide layer is preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.3 μm. With the above thickness, good adhesion tends to be achieved with high productivity.
<Electroless Copper Plating Deposit>An electroless copper plating deposit according to the present invention is formed on a metal oxide layer formed on a surface of a glass or ceramic substrate and has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more. The presence of these metals allows the metal oxide layer to exhibit good peel strength to the glass or ceramic substrate, particularly glass substrate.
The combined amount is preferably 0.2% by mass or more, more preferably 0.4% by mass or more, still more preferably 0.7% by mass or more, particularly preferably 0.9% by mass or more, most preferably 1.1% by mass or more, further most preferably 1.3% by mass or more, further most preferably 1.7% by mass or more, further most preferably 2.0% by mass or more, further most preferably 2.3% by mass or more, further most preferably 2.7% by mass or more, further most preferably 3.0% by mass or more, further most preferably 3.3% by mass or more, further most preferably 3.7% by mass or more. Although the upper limit is not limited, it is preferably 7.0% by mass or less, more preferably 6.0% by mass or less, still more preferably 5.0% by mass or less, particularly preferably 4.7% by mass or less, most preferably 4.3% by mass or less, further most preferably 4.0% by mass or less, because too high an amount of the metals increases the specific resistance of the plating deposit, which may hinder the throwing power of the subsequent electrolytic copper plating. The above amount tends to allow the metal oxide layer to exhibit better peel strength to the glass or ceramic substrate, particularly glass substrate.
After the electroless copper plating deposit is formed on the metal oxide layer on formed the surface of the glass or ceramic substrate, heat treatment is usually performed to allow the plating deposit to exhibit good adhesion to the glass or ceramic substrate, particularly glass substrate. The studies of the present inventors revealed that this heat treatment may cause the copper in the electroless copper plating deposit to migrate through the metal oxide layer to the glass surface, thereby reducing the adhesion.
Accordingly, the presence of a certain amount of the metals is preferable to more suitably prevent copper diffusion. Thus, the lower limit of the combined amount is preferably 0.1% by mass or more, more preferably 1.1% by mass or more, still more preferably 2.5% by mass or more, particularly preferably 4.0% by mass or more. The upper limit is as described above.
Preferred among nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium are nickel, cobalt, gold, silver, and platinum, with nickel, cobalt, and platinum being more preferred, with nickel and cobalt being still more preferred, with nickel being particularly preferred. Also preferred are nickel, cobalt, platinum, iron, manganese, titanium, and vanadium.
Another suitable embodiment of the electroless copper plating deposit of the present invention is an electroless copper plating deposit which is formed on a metal oxide layer formed on a surface of a glass or ceramic material, in which the metal oxide is a zinc-containing oxide, and which has a combined amount of nickel, cobalt, platinum, iron, manganese, titanium, and vanadium of 0.1% by mass or more.
The thickness of the electroless copper plating deposit is preferably 0.1 to 2 μm, more preferably 0.5 to 1 μm. When the thickness is 0.1 μm or more, the dissolution of the metal oxide layer can be further reduced even when using a strong acid electrolytic copper plating bath, and it tends to be possible to reduce a decrease in adhesion. When the thickness is 2 μm or less, it is possible to further prevent insufficient adhesion between the glass or ceramic substrate and the metal oxide due to the stress of the electroless copper plating deposit.
A plating deposit may be produced by any method that can form an electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more on a metal oxide layer formed on a surface of a glass or ceramic substrate. Preferably, an electrolytic copper plating deposit is further formed on the electroless copper plating deposit.
A preferred example of a method of producing a plating deposit includes the steps of:
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- (1) forming a metal oxide layer on a surface of a glass or ceramic substrate, preferably a glass substrate;
- (2) performing a first heat treatment after the step (1);
- (3) forming an electroless copper plating deposit on the metal oxide layer after the step (2);
- (4) performing a second heat treatment after the step (3); and
- (5) forming an electrolytic copper plating deposit on the electroless copper plating deposit after the step (4). This method enables the production of a plating deposit with good adhesion to a glass or ceramic substrate, particularly a glass substrate. In the method of producing a plating deposit, the steps (1) to (5) are performed in this order. However, the method may include additional steps between these steps as long as the steps (1) to (5) are performed in this order (i.e., the order from step (1) to step (2) to step (3) to step (4) to step (5)). Moreover, a usual post treatment such as water washing or drying may be performed after each step described below.
The method of producing a plating deposit provides the above-described advantageous effect presumably due to the following reason.
The adhesion between the glass or ceramic substrate, particularly glass substrate, and the metal oxide can be further increased by performing the step (1) of forming the metal oxide layer on the surface of the glass or ceramic substrate, particularly glass substrate, and the step (2) of performing a first heat treatment after the step (1). Further, the adhesion between the metal oxide layer and the electroless copper plating deposit can be further increased by performing the step (3) of forming the electroless copper plating deposit on the metal oxide layer after the step (2), and the step (4) of performing a second heat treatment after the step (3).
The plating deposit formed on the surface of the glass or ceramic substrate, particularly glass substrate, through the steps (1) to (4) has good adhesion to the glass or ceramic substrate, particularly glass substrate, with strong adhesion between the glass or ceramic substrate, particularly glass substrate, and the metal oxide and strong adhesion between the metal oxide layer and the electroless copper plating deposit. Such a plating deposit is very favorable as a base for an electrolytic copper plating deposit. Thus, a plating deposit with good adhesion to the glass or ceramic substrate, particularly glass substrate, can be produced by forming an electrolytic copper plating deposit on the plating deposit formed on the surface of the glass or ceramic substrate through the steps (1) to (4).
Moreover, in the method of producing a plating deposit in which the steps (1) to (5) are performed in this order, a metal oxide layer and an electroless copper plating deposit can be uniformly formed regardless of the shape of the object to be treated. For this reason, the method is excellent in the deposition and adhesion to the surface of a glass or ceramic substrate or to the inside of through holes in the substrate.
<Step (1)>The step (1) includes forming a metal oxide layer on a surface of a glass or ceramic substrate. The step (1) is not limited as long as it includes forming a metal oxide layer on a surface of a glass or ceramic substrate. For example, the step (1) may include the steps (1-1) to (1-3) described below, for example, the steps (1-1) to (1-3) performed in the following order: the step (1-1), the step (1-2), and the step (1-3). In particular, the step (1) preferably includes the steps (1-2) and (1-3), more preferably the steps (1-2) and (1-3) performed in the order from the step (1-2) to the step (1-3).
<<Step (1-1)>>The step (1-1) includes removing contaminants (foreign substances) from the surface of the glass or ceramic substrate. Thus, organic residues adsorbed to the surface of the glass or ceramic substrate can be removed, and the OH groups on the surface of the glass or ceramic substrate, particularly glass substrate, can be increased to improve the hydrophilicity.
In the step (1-1), for example, the surface of the glass or ceramic substrate may be washed with at least one selected from the group consisting of organic solvents, alkaline solutions, and acidic solutions. Each of these may be used alone, or two or more of these may be used in combination. When the surface of the glass or ceramic substrate is washed with an organic solvent, organic residues adsorbed to the surface of the glass or ceramic substrate can be removed. When the surface of the glass or ceramic substrate is washed with an alkaline solution or an acidic solution, organic residues adsorbed to the surface of the glass or ceramic substrate can be removed, and at the same time the OH groups on the surface of the glass or ceramic substrate, particularly glass substrate, can be increased to improve the hydrophilicity.
Examples of usable organic solvents include methanol, ethanol, acetone, ethyl acetate, and hexane. Each of these may be used alone, or two or more of these may be used in combination.
The conditions for glass washing with an organic solvent are not limited.
Examples of usable alkaline solutions include NaOH solutions and KOH solutions. Each of these may be used alone, or two or more of these may be used in combination.
The conditions for glass washing with an alkaline solution are not limited.
Examples of usable acidic solutions include sulfuric acid, hydrochloric acid, nitric acid, hydrogen peroxide/sulfuric acid, and hydrogen peroxide/nitric acid. Each of these may be used alone, or two or more of these may be used in combination.
The conditions for glass washing with an acidic solution are not limited.
<<Step (1-2)>>The step (1-2) includes applying a catalyst (catalytic metal) to the surface of the glass or ceramic substrate. Thus, the surface of the glass or ceramic substrate can be activated so that a metal oxide layer can be more suitably formed on the surface of the glass or ceramic substrate. With the step (1-2), it is also possible to form a metal oxide layer without roughening the surface of the glass or ceramic substrate. Thus, fine pitch trace patterns can be formed in circuit formation, and the influence on the transmission loss in a high frequency band can also be reduced. Moreover, although a fluoride is usually used to roughen the surface of a glass or ceramic substrate, the use of a fluoride is inappropriate in view of the safety of the human body and environmental protection. With the step (1-2), it is possible to form a metal oxide layer on the surface of the glass or ceramic substrate without using a fluoride.
The catalytic metal used may be any metal that has catalytic activity for forming a metal oxide layer in the subsequent step. Examples include Ag, Pd, Pt, and Au. Each of these may be used alone, or two or more of these may be used in combination. Among these, Pd and Ag are preferred, with Pd being more preferred.
The method for applying a catalyst to the surface of the glass or ceramic substrate is also not limited because what is important is to apply a catalyst (catalytic metal) to the surface of the glass or ceramic substrate. Examples include a method in which metal ions are adsorbed onto the glass or ceramic substrate to reduce them to the metal, and a method in which metal colloids are adsorbed onto the glass or ceramic substrate. Each of these may be used alone, or two or more of these may be used in combination. The conditions for catalyst application are also not limited for the same reason.
An exemplary specific method of the step (1-2) may include cleaner conditioning (promotion of catalyst adsorption, uniform catalyst adsorption), predipping, catalyst application (activator), and activation treatment (accelerator) performed in this order.
<<Step (1-3)>>The step (1-3) includes forming a metal oxide layer on the surface of the glass or ceramic substrate. Thus, a metal oxide layer can serve as an intermediate layer between the glass and an electroless copper plating, so that the adhesion between the glass and the electroless copper plating can be easily improved.
In the step (1-3), a metal oxide layer is preferably formed on the surface of the glass or ceramic substrate to which the catalyst (catalytic metal) has been applied. In this case, the advantageous effect tends to be more suitably achieved.
The metal oxide is preferably a zinc-containing oxide, and examples thereof include zinc oxide and oxides of alloys containing zinc and at least one metal selected from the group consisting of titanium, aluminum, silicon, tin, zirconium, nickel, indium, vanadium, chromium, iron, manganese, cobalt, and copper. Each of these may be used alone, or two or more of these may be used in combination. Preferred among these are zinc oxide and oxides of alloys containing zinc and at least one metal selected from the group consisting of indium, titanium, silicon, tin, manganese, and cobalt, with zinc oxide being more preferred.
The thickness of the metal oxide layer is preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.3 μm. With the above thickness, good adhesion tends to be achieved with high productivity.
For example, the metal oxide layer may be formed by immersing the catalyst-applied glass or ceramic substrate in a treatment liquid for metal oxide layer formation. The treatment liquid for metal oxide layer formation is preferably an aqueous solution containing zinc ions, nitrate ions, and an amine-borane compound.
The zinc ion source used may be a water-soluble zinc salt, and examples thereof include zinc nitrate, zinc sulfate, zinc chloride, zinc acetate, zinc phosphate, zinc pyrophosphate, and zinc carbonate. Zinc nitrate is preferred among these. Each of these may be used alone, or two or more of these may be used in combination.
The nitrate ion source used may be nitric acid, a water-soluble nitrate, or other sources, and examples thereof include nitric acid, zinc nitrate, ammonium nitrate, sodium nitrate, potassium nitrate, lithium nitrate, and urea nitrate. Zinc nitrate is preferred among these. Each of these may be used alone, or two or more of these may be used in combination.
Preferably, zinc nitrate alone is used as an ion source of both the zinc ions and the nitrate ions.
The zinc ion concentration and nitrate ion concentration in the treatment liquid for metal oxide layer formation may be adjusted in a wide range. However, if even one of these ion concentrations is too low, a metal oxide film cannot be formed, while if even one of these ion concentrations is too high, a metal hydroxide film can be easily formed, so that the purity of the metal oxide film tends to decrease. Thus, the zinc ion concentration and nitrate ion concentration are each preferably within a range of about 0.001 mol/l to about 0.5 mol/l (0.065 to 32.7 g/l in terms of zinc content), more preferably within a range of about 0.01 mol/l to about 0.2 mol/l (0.65 to 13 g/l in terms of zinc content).
The amine-borane compound may be any water-soluble amine-borane compound, and examples thereof include dimethylamine-borane and trimethylamine-borane. Each of these may be used alone, or two or more of these may be used in combination. Dimethylamine-borane is preferred among these.
The amine-borane compound concentration in the treatment liquid for metal oxide layer formation is preferably 0.3 to 20 g/L, more preferably 0.5 to 5 g/L. With the above concentration, good metal oxide deposition tends to be achieved with high productivity.
The pH of the treatment liquid for metal oxide layer formation is preferably 3.0 to 7.0, more preferably 4.0 to 7.0. With the above pH, good metal oxide deposition tends to be achieved with high productivity.
The temperature in the metal oxide formation treatment is preferably 50° C. to 90° C., more preferably 60° C. to 85° C. At the above temperature, the decomposition reaction rate of the amine-borane compound can be adjusted within an appropriate range, and good metal oxide deposition tends to be achieved.
The duration of the metal oxide formation treatment is preferably 2 to 180 minutes, more preferably 5 to 60 minutes, still more preferably 10 to 30 minutes. When the duration is two minutes or more, a metal oxide layer having a sufficient thickness can be formed, and sufficient adhesion between the glass or ceramic substrate and the metal oxide tends to be achieved. Moreover, although a duration of more than 180 minutes is usually required to form a metal oxide layer, the present invention can reduce the treatment duration by using an aqueous solution containing zinc ions, nitrate ions, and an amine-borane compound as a treatment liquid for metal oxide layer formation, and thus can form a metal oxide layer with high productivity and cost advantages.
The steps (1-2) and (1-3) enable the formation of a metal oxide layer on the surface of the glass or ceramic substrate without using a fluoride. The amount of fluorine in the metal oxide layer is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, still more preferably zero (0% by mass) based on 100% by mass of the metal oxide layer. With the above amount, the advantageous effect tends to be more suitably achieved.
Herein, the amount of fluorine is measured using a fluoride ion electrode.
The method of producing a plating deposit according to the present invention does not need to use a fluoride and therefore does not require a step of removing fluorine from the metal oxide layer. In other words, the method of producing a plating deposit according to the present invention, which does not include a step of removing fluorine from the metal oxide layer, can produce a plating deposit with good adhesion to the glass or ceramic substrate with high productivity.
<Step (2)>The step (2) includes performing a first heat treatment after the step (1). Specifically, in the step (2), the glass or ceramic substrate in which a metal oxide layer has been formed on the surface in the step (1) is subjected to a first heat treatment. Thus, some metal hydroxide remaining in the metal oxide layer formation in the step (1) can be converted to a metal oxide by a dehydration reaction, and chemical bonds can be formed between the glass or ceramic substrate, particularly glass substrate, and the metal oxide by condensation of OH groups. Consequently, the adhesion between the glass or ceramic substrate, particularly glass substrate, and the metal oxide can be further increased.
Although the step (2) may be performed in any atmosphere, the atmosphere preferably contains oxygen to promote the dehydration reaction. Thus, for example, the step (2) may be performed in the air atmosphere.
The temperature in the heat treatment is preferably 100° C. to 800° C., more preferably 200° C. to 600° C., still more preferably 250° C. to 500° C., particularly preferably 300° C. to 450° C., most preferably 300° C. to 350° C. When the temperature is 100° C. or higher, the dehydration reaction tends to proceed sufficiently, resulting in better adhesion between the glass or ceramic substrate and the metal oxide. When the temperature is 800° C. or lower, it tends to be possible to further reduce the dimensional changes, such as warpage or distortion, of the glass or ceramic substrate.
The duration of the heat treatment is preferably 5 to 180 minutes, more preferably 15 to 90 minutes, still more preferably 25 to 90 minutes. With the above duration, the dehydration reaction tends to proceed sufficiently without reducing the productivity, resulting in better adhesion between the glass or ceramic substrate and the metal oxide.
<Step (3)>The step (3) includes forming an electroless copper plating deposit on the metal oxide layer after the step (2). Specifically, in the step (3), an electroless copper plating deposit is formed on the heat-treated metal oxide layer after the step (2).
The step (3) is not limited as long as it includes forming an electroless copper plating deposit on the metal oxide layer. For example, the step (3) may include the steps (3-1) and (3-2) described below, for example, the steps (3-1) and (3-2) performed in the order from the step (3-1) to the step (3-2).
<<Step (3-1)>>The step (3-1) includes applying a catalyst (catalytic metal) to a surface of the metal oxide layer. Thus, the surface of the metal oxide layer can be activated, and an electroless copper plating deposit can be more suitably formed on the surface of the metal oxide layer. Moreover, with the step (3-1), it is possible to form an electroless copper plating deposit without roughening the surface of the metal oxide layer. Thus, the influence on the transmission loss in a high frequency band can also be reduced.
The catalytic metal may be any metal that has catalytic activity for forming an electroless copper plating deposit in the subsequent step. Examples include Cu, Ni, Ag, Pd, Pt, and Au. Each of these may be used alone, or two or more of these may be used in combination. Pd, Ag, and Pt are preferred among these, with Pd being more preferred.
The method for applying a catalyst is not limited because what is important is to apply a catalyst (catalytic metal) to the surface of the metal oxide layer. Examples include a method in which metal ions are substituted on the metal oxide, and (1) metal ion substitution may be followed by (2) immersion in a reducing agent solution to activate the catalytic metal. The composition of the catalyst application bath is also not limited.
The pH of the catalyst application bath is preferably 3.0 to 13, more preferably 4.0 to 7.0. With the above pH, the dissolution of the metal oxide layer can be further reduced, and a decrease in adhesion can be further reduced.
Herein, the pH is measured at 25° C.
Herein, the metal concentrations or the amounts of metals are measured using an inductively coupled plasma (ICP) emission spectrometer.
Also, herein, the concentration of each compound in the liquid is measured by liquid chromatography (Shimadzu Corporation).
The catalyst (catalytic metal) can be applied to the surface of the metal oxide layer by bringing the surface of the metal oxide layer into contact with the catalyst application bath. Specific methods are not limited. Usually, the object to be treated may be immersed in the catalyst application bath. Alternatively, the catalyst application treatment can also be performed, for example, by spraying or applying the catalyst application bath to the surface of the material to be electroless plated.
The temperature in the catalyst application treatment is preferably 10° C. to 60° C., more preferably 20° C. to 40° C. When the temperature is 10° C. or higher, the amount of catalyst application tends to be sufficient, resulting in good electroless copper plating deposition. When the temperature is 60° C. or lower, the dissolution of the metal oxide layer can be further reduced, and a decrease in adhesion can be further reduced.
The duration of the catalyst application treatment is preferably 10 seconds to 10 minutes, more preferably 30 seconds to 5 minutes. When the duration is 10 seconds or more, the amount of catalyst application tends to be sufficient, resulting in good electroless copper plating deposition. When the duration is 10 minutes or less, the dissolution of the metal oxide layer can be further reduced, and a decrease in adhesion can be further reduced.
When (1) metal ion substitution is followed by activating the catalytic metal, examples of the reducing agent used in the treatment (2) include dimethylamine-borane, trimethylamine-borane, sodium hypophosphite, sodium phosphite, formaldehyde, glyoxylic acid, hydrazine, and sodium formate. Each of these may be used alone, or two or more of these may be used in combination.
The treatment conditions (temperature, etc.) for activating the catalytic metal are not limited as long as the bath used is of a type having a pH of 3.0 or more. When the pH is 3.0 or more, the dissolution of the metal oxide layer can be further reduced, and a decrease in adhesion can be further reduced.
Another feature of the present invention is to perform a step (3-1) of applying a catalyst (catalytic metal) to the surface of the metal oxide layer after the first heat treatment. Thus, a plating deposit with good adhesion to the glass or ceramic substrate can be produced with high productivity.
In contrast, if the first heat treatment is performed after applying a catalyst (catalytic metal) to the surface of the metal oxide layer, the catalyst may be oxidized so that an electroless copper plating deposit cannot be formed sufficiently. This necessitates a reduction treatment after the heat treatment, thereby reducing the productivity.
<<Step (3-2)>>The step (3-2) includes forming an electroless copper plating deposit on the heat-treated metal oxide layer. This step imparts conduction to the metal oxide layer, enabling electrolytic copper plating.
In the step (3-2), an electroless copper plating deposit is preferably formed on the surface of the metal oxide layer to which the catalyst (catalytic metal) has been applied. In this case, the advantageous effect tends to be more suitably achieved.
The thickness of the electroless copper plating deposit is preferably 0.1 to 2 μm, more preferably 0.5 to 1 μm. When the thickness is 0.1 μm or more, the dissolution of the metal oxide layer can be further reduced even when using a strong acid electrolytic copper plating bath, and it tends to be possible to reduce a decrease in adhesion. When the thickness is 2 μm or less, it is possible to further prevent insufficient adhesion between the glass or ceramic substrate and the metal oxide due to the stress of the electroless copper plating deposit.
For example, the electroless copper plating deposit may be formed by bringing an electroless copper plating bath into contact with the surface of the metal oxide layer to which the catalyst (catalytic metal) has been applied.
<<Electroless Copper Plating Bath>>The electroless copper plating bath is not limited. The treatment conditions (temperature, pH, etc.) for electroless copper plating are not limited either.
In order to suitably form the electroless copper plating deposit according to the present invention (electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more), the electroless copper plating bath according to the present invention preferably has a combined amount (combined concentration) of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium, preferably nickel, cobalt, platinum, iron, manganese, titanium, and vanadium, of 0.1 mmol/l or more. The use of an electroless copper plating bath containing nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and/or vanadium enables the production of the electroless copper plating deposit according to the present invention containing these metals.
The electroless copper plating bath having a combined amount (combined concentration) of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1 mmol/l or more is an electroless copper plating bath for use in forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic substrate, more specifically, an electroless copper plating bath for use in forming an electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more on a metal oxide layer formed on a surface of a glass or ceramic substrate. Thus, the electroless copper plating bath having a combined amount (combined concentration) of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1 mmol/l or more can be suitably used to form an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic substrate. More specifically, it can be suitably used to form an electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more on a metal oxide layer formed on a surface of a glass or ceramic substrate.
When the electroless copper plating bath according to the present invention is used to form an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic substrate, it is possible to produce the electroless copper plating deposit according to the present invention (electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more).
The combined amount (combined concentration) of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium in the electroless copper plating bath is 0.1 mmol/l or more, preferably 0.2 to 30 mmol/l, more preferably 0.5 to 25 mmol/l, still more preferably 1.0 to 20 mmol/l. A person skilled in the art can appropriately adjust the combined amount so that the resulting electroless copper plating deposit will contain the target amount of the specific metals.
The amount (concentration) of the metals in the electroless copper plating bath can be measured using an inductively coupled plasma (ICP) emission spectrometer.
The electroless copper plating bath having the above-described metal concentration may be prepared by appropriately incorporating a water-soluble metal compound (water-soluble metal salt) into an electroless copper plating bath. For example, a nickel-containing electroless copper plating bath may be prepared by incorporating a water-soluble nickel compound (water-soluble nickel salt) into an electroless copper plating bath.
The electroless copper plating bath is the same as in the conventional art, except that it appropriately incorporates a water-soluble metal compound so that the resulting electroless copper plating deposit will contain the target amount of the specific metals. In other words, the electroless copper plating bath may contain a water-soluble copper compound and a water-soluble metal compound other than water-soluble copper compounds, as well as a stabilizer, a chelating or complexing agent, a reducing agent, water, a surfactant, and/or a pH adjuster. Each of these may be used alone, or two or more of these may be used in combination.
The water-soluble copper compound (water-soluble copper salt) is contained as a copper ion source, and examples thereof include copper compound salts such as copper sulfate, copper chloride, copper oxide, copper carbonate, copper pyrophosphate, copper fluoroborate, copper methanesulfonate, copper propanesulfonate, copper isethionate, and copper propanol sulfonate. Each of these copper compounds may be used alone, or two or more of these may be used in combination. The concentration of copper in the electroless copper plating bath is preferably 10 to 200 mmol/l, more preferably 20 to 100 mmol/l.
Here, the ratio of the combined amount (combined concentration (mmol/l)) of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium to the amount (concentration (mmol/l)) of copper in the electroless copper plating bath is preferably 0.001 to 1, more preferably 0.005 to 0.8, still more preferably 0.01 to 0.6. At the above ratio, the electroless copper plating deposit according to the present invention (electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more) can be more suitably formed.
Examples of the stabilizer include sulfur compounds such as s-carboxymethyl-L-cysteine, thioglycolic acid, thiosuccinic acid, 2,2′-dithiosuccinic acid, mercaptopyridine, mercaptobenzothiazole, and thiourea; compounds such as pyridine, purine, quinoline, indole, indazole, imidazole, pyrazine, and derivatives thereof; alcohols such as alkyne alcohols, allyl alcohol, aryl alcohols, and cyclic phenols; hydroxy-substituted aromatic compounds such as methyl 3,4,5-trihydroxybenzoate, 2,5-dihydroxy-1,4-benzoquinone, and 2,6-dihydroxynaphthalene; carboxylic acids such as citric acid, tartaric acid, succinic acid, malic acid, malonic acid, lactic acid, acetic acid, and salts thereof; amines; amino acids; water-soluble metal compounds such as metal chlorides or sulfates; silicon compounds such as silanes, siloxanes, and low- to medium-molecular-weight polysiloxanes; germanium and its oxides or hydrides; cyanide or ferricyanide compounds; and polyalkylene glycols, cellulose compounds, alkylphenyl ethoxylates, and polyoxyethylene compounds, as well as pyridazine, methylpiperidine, 1,2-di-(2-pyridyl)ethylene, 1,2-di(pyridyl)ethylene, 2,2′-dipyridylamine, 2,2′-dipyridyl, 2,2′-bipyridyl, 2,2′-bipyrimidine, 6,6′-dimethyl-2,2′-dipyridyl, di-2-pyridyl ketone, N,N,N′,N′-tetraethylenediamine, naphthalene, 1,8-naphthyridine, 1,6-naphthyridine, tetrathiafulvalene, terpyridine, phthalic acid, isophthalic acid, and 2,2′-dibenzoic acid. Each of these may be used alone, or two or more of these may be used in combination.
The concentration of stabilizers in the electroless copper plating bath is preferably 0.5 ppm to 200 ppm, more preferably 1 ppm to 50 ppm.
Examples of the chelating or complexing agent include potassium sodium tartrate tetrahydrate (i.e., Rochelle salt), sodium tartrate, sodium salicylate, sodium salt of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid and its alkali metal salts, gluconic acid, gluconates, triethanolamine, modified ethylenediaminetetraacetic acid, S,S-ethylenediaminedisuccinic acid, and hydantoin and hydantoin derivatives. Non-limiting examples of the hydantoin derivatives include 1-methylhydantoin, 1,3-dimethylhydantoin, and 5,5-dimethylhydantoin. Each of these may be used alone, or two or more of these may be used in combination.
The concentration of chelating agents and/or complexing agents in the electroless copper plating bath is preferably 10 g/L to 150 g/L, more preferably 20 g/L to 150 g/L, still more preferably 30 g/L to 100 g/L.
Examples of the reducing agent include formaldehyde, formaldehyde precursors, formaldehyde derivatives (such as paraformaldehyde), borohydrides (such as sodium borohydride), substituted borohydrides, boranes (such as dimethylamine borane (DMAB)), sugars (such as glucose, sorbitol, cellulose, sucrose, mannitol, and gluconolactone), hypophosphorous acid and its salts (such as sodium hypophosphite), hydroquinone, catechol, resorcinol, quinol, pyrogallol, hydroxyquinol, phloroglucinol, guaiacol, gallic acid, 3,4-dihydroxybenzoic acid, phenolsulfonic acid, cresolsulfonic acid, hydroquinonesulfonic acid, catechol sulfonic acid, tiron, and salts of any of the aforementioned reducing agents. Each of these may be used alone, or two or more of these may be used in combination.
The concentration of reducing agents in the electroless copper plating bath is preferably 1 g/L to 10 g/L.
<Step (4)>The step (4) includes performing a second heat treatment after the step (3). Specifically, in the step (4), the glass or ceramic substrate in which an electroless copper plating deposit has been formed on the surface in the step (3) is subjected to a second heat treatment. Thus, a diffusion layer can be formed between the metal oxide layer and the electroless copper plating deposit, and the adhesion between the metal oxide and the electroless copper plating can be further increased.
The step (4) may be performed in the air atmosphere or an inert gas atmosphere.
The temperature in the heat treatment is preferably 80° C. to 300° C., more preferably 100° C. to 250° C., still more preferably 120° C. to 220° C. When the temperature is 80° C. or higher, a diffusion layer tends to be formed sufficiently, resulting in better adhesion between the metal oxide and the electroless copper plating. When the temperature is 300° C. or lower, it tends to be possible to further reduce the dimensional changes, such as warpage or distortion, of the glass or ceramic substrate.
The duration of the heat treatment is preferably 5 to 180 minutes, more preferably 15 to 90 minutes, still more preferably 25 to 90 minutes. With the above duration, a diffusion layer tends to be formed sufficiently without reducing the productivity, resulting in better adhesion between the metal oxide and the electroless copper plating.
<Step (5)>The step (5) includes forming an electrolytic copper plating deposit on the electroless copper plating deposit after the step (4). Specifically, in the step (5), an electrolytic copper plating deposit is formed on the heat-treated electroless copper plating deposit after the step (4).
Although the thickness of the electrolytic copper plating deposit is not limited, it is, for example, 10 to 20 μm.
For example, the electrolytic copper plating deposit may be formed by bringing an electrolytic copper plating bath into contact with the electroless copper plating deposit.
Although the electrolytic copper plating bath is not limited, it preferably contains a water-soluble copper salt, sulfuric acid, and chloride ions.
The water-soluble copper salt is contained as a copper ion source, and examples thereof include copper compound salts such as copper sulfate, copper chloride, copper oxide, copper carbonate, copper pyrophosphate, copper fluoroborate, copper methanesulfonate, copper propanesulfonate, copper isethionate, and copper propanol sulfonate. Each of these copper compounds may be used alone, or two or more of these may be used in combination. In the case of copper sulfate, for example, the concentration of the water-soluble copper salt in the copper plating bath is preferably 30 to 300 g/L, more preferably 70 to 90 g/L, as calculated as copper sulfate pentahydrate.
The sulfuric acid concentration in the electrolytic copper plating bath is preferably 30 to 300 g/L, more preferably 180 to 220 g/L. When the sulfuric acid concentration is 30 g/L or more, the copper film thickness within the plated surface tends to be uniform. When the sulfuric acid concentration is 300 g/L or less, it tends to be possible to sufficiently dissolve the water-soluble copper salt.
The chloride ion concentration in the electrolytic copper plating bath is preferably 5 to 150 mg/L, more preferably 20 to 100 mg/L, still more preferably 30 to 60 mg/L. When the chloride ion concentration is 150 mg/L or less, it tends to be possible to further suppress the passivation of the anode caused by formation of copper chloride on the anode surface. When the chloride ion concentration is 5 mg/L or more, it tends to be possible to inhibit the suppressing action from partially taking place and to further reduce the risk of step plating.
The electrolytic copper plating bath preferably contains a leveler (leveling agent) in addition to the above-described components. Here, the term “leveler” refers to an additive including a nitrogen-containing compound, which can act as a cation in an acidic plating bath and electrically concentrate on a high current density portion, for example, on the outer surface side of via holes or through holes in the object to be plated, thereby increasing the activation overvoltage and inhibiting copper deposition. On the other hand, the leveler will be less adsorbed to the bottom of fine grooves or holes, or other similar locations to allow copper to preferentially deposit there for bottom-up deposition, thereby exhibiting leveling properties.
The leveler may be any nitrogen-containing organic compound. Examples include polyethylene imine and derivatives thereof, polyvinyl imidazole and derivatives thereof, polyvinyl alkyl imidazoles and derivatives thereof, copolymers of vinylpyrrolidone and vinyl alkyl imidazoles or derivatives thereof, dyes such as Janus Green B, diallyl dimethyl ammonium chloride polymers, diallyl dimethyl ammonium chloride/sulfur dioxide copolymers, partially 3-chloro-2-hydroxypropylated diallylamine hydrochloride/diallyl dimethyl ammonium chloride copolymers, diallyl dimethyl ammonium chloride/acrylamide copolymers, diallylamine hydrochloride/sulfur dioxide copolymers, allylamine hydrochloride polymers, (free) allylamine polymers, allylamine hydrochloride/diallylamine hydrochloride copolymers, diamine/epoxy polymerization products, morpholine/epichlorohydrin polymerization products, and epichlorohydrin-modified products of polycondensates of diethylenetriamine, adipic acid, and ε-caprolactam.
The leveler concentration in the electrolytic copper plating bath is preferably 0.01 to 3000 mg/L.
The electrolytic copper plating bath preferably contains a brightener in addition to the above-described components. The term “brightener” refers to an additive that can inhibit the growth of crystals and promote the formation of growth nuclei in plating deposition to form a dense microcrystalline plating deposit. It enables the production of a glossy deposit.
The brightener may be any sulfur-containing organic compound, and examples thereof include sulfur-containing compounds represented by the following formulas:
wherein R1 represents a hydrogen atom or a group represented by the formula: —(S)m—(CH2)n—(O)p—SO3M; each R2 independently represents a C1-C5 alkyl group; M represents a hydrogen atom or an alkali metal; m is 0 or 1; n is an integer of 1 to 8; and p is 0 or 1.
The brightener concentration in the electrolytic copper plating bath is preferably 0.01 to 1000 mg/L.
The electrolytic copper plating bath preferably contains a carrier in addition to the above-described components. The term “carrier” refers to an additive that can adsorb to the copper surface by interaction with chloride ions to form a monomolecular film, thereby uniformly inhibiting the growth of crystals. It improves uniform electrodeposition.
The carrier may be any polyether compound. Examples of the polyether compound include compounds containing polyalkylene glycols with at least four —O— groups. Further, specific examples include polyethylene glycol, polypropylene glycol, and copolymers of these glycols, polyethylene glycol fatty acid esters, and polyethylene glycol alkyl ethers.
The carrier concentration in the electrolytic copper plating bath is preferably 5 to 5000 mg/L.
The treatment conditions for electrolytic copper plating are not limited. However, the pH of the electrolytic copper plating bath is preferably 6.0 or less, more preferably 4.0 or less, still more preferably 2.0 or less, particularly preferably 1.5 or less. The lower limit is not limited. With the above pH, the advantageous effect tends to be more suitably achieved. Moreover, the temperature in the electrolytic copper plating is preferably 37° C. to 43° C., and the current density is preferably 3 to 5 A/dm2.
<<Other Steps>>The method of producing a plating deposit according to the present invention includes the steps (1) to (5) in this order. The method may include other steps as long as the steps (1) to (5) are performed in this order.
Although the total thickness of the plating deposit (plating deposit laminate) produced by the method of producing a plating deposit according to the present invention is not limited, it is, for example, 10 to 20 μm.
Herein, the thickness and total thickness of the plating deposits, etc. are each the average of those measured at five locations using an X-ray fluorescence spectrometer.
The treatment conditions and concentration settings in the treatments described above are not limited to the conditions described above and may obviously be changed appropriately depending on the thickness of the deposit to be formed and other factors.
The plating deposit produced by the method of producing a plating deposit according to the present invention has good adhesion to a glass or ceramic substrate. Therefore, the plating deposit according to the present invention is preferably used in a printed circuit board or package substrate, more preferably a high-density printed circuit board, for an electronic device. Since the present invention enables the formation of a plating deposit (traces) with good adhesion to a glass substrate, the plating deposit is most suitable for the production of electronic devices with increasingly higher communication speeds.
Examples of the electronic devices include home appliances, in-vehicle equipment, power transmission systems, transportation equipment, and communication equipment. Specific examples include power modules for power control units and other components for air conditioners, elevators, electric vehicles, hybrid vehicles, trains, and power generation equipment, general home appliances, and personal computers.
EXAMPLESThe present invention will be specifically described with reference to examples, but the invention is not limited to these examples. In the tables, the unit “% by mass” may also be written as wt % or %.
An alkali-free glass (EAGLE XG, available from Corning) cut into a 50 mm×50 mm size was used as a glass substrate. A plating deposit was formed on the glass substrate according to the conditions shown in Table 1. Here, the steps in Table 1 were performed in the order from top to bottom. It should be noted that if there is a discrepancy between the conditions in the tables and those described in the main body, the conditions in the tables shall take precedence.
(Step (1-1))The surface of the glass substrate was subjected to alcohol washing using ethanol at 25° C. for five minutes and then washed with water at a temperature of 25° C. for one minute. Next, the surface of the glass substrate was subjected to alkali washing using a sodium hydroxide aqueous solution at 50° C. for five minutes and then washed with water at a temperature of 25° C. for one minute.
(Step (1-2))The surface of the glass substrate was subjected to cleaner conditioning using THRU-CUP MTE-1A available from C. Uyemura & Co., Ltd. at 50° C. for five minutes, then washed with water at a temperature of 40° C. for one minute, and further washed with water at a temperature of 25° C. for one minute. Next, the surface of the glass substrate was subjected to predipping using THRU-CUP PED-104 available from C. Uyemura & Co., Ltd. at 25° C. for two minutes. Subsequently, activator treatment was performed using THRU-CUP AT-105 available from C. Uyemura & Co., Ltd. at 30° C. for eight minutes, followed by water washing at a temperature of 25° C. for one minute. Thereafter, the surface of the glass substrate was subjected to accelerator treatment using THRU-CUP ALF-406-A ACCELERATOR available from C. Uyemura & Co., Ltd. at 25° C. for three minutes and then washed with water at a temperature of 25° C. for one minute. Palladium (Pd) was applied to the surface of the glass substrate by the step (1-2).
(Step (1-3))The catalyst-applied glass substrate was immersed in the treatment liquid for metal oxide layer formation (containing zinc nitrate hexahydrate and dimethylamine-borane, pH 6.0) shown in Table 1 at 80° C. for 20 minutes. Subsequently, the glass substrate was washed with water at a temperature of 25° C. for one minute and then dried with a dryer at a temperature of 60° C. for 10 minutes. Thus, a metal oxide layer (zinc oxide layer, thickness 0.3 μm) was formed on the surface of the glass substrate.
(Step (2))The glass substrate with the metal oxide layer formed thereon was subjected to a first heat treatment (in the air, 300° C., 30 minutes).
(Step (3-1))The glass substrate heat-treated in the step (2) was immersed in a catalyst application bath (ALCUP MAT-2-A ACTIVATOR available from C. Uyemura & Co., Ltd., pH 5.0) at 25° C. for five minutes. Subsequently, the glass substrate was washed with water at a temperature of 25° C. for one minute. Thus, palladium (Pd) was applied to the surface of the metal oxide layer.
(Step (3-2))The glass substrate obtained in the step (3-1) was immersed in an electroless copper plating bath at 36° C. for 25 minutes. Subsequently, the glass substrate was washed with water at a temperature of 25° C. for one minute and then dried with a dryer at a temperature of 60° C. for 10 minutes. Thus, an electroless copper plating deposit (thickness 0.7 μm) was formed on the surface of the metal oxide layer. Table 2 shows an example of an electroless copper plating bath used to form an electroless copper plating deposit containing nickel in an amount of 1.0% by mass or 4.0% by mass. Electroless copper plating deposits of Comparative Example 1 and Examples 1 to 6 were formed by appropriately adjusting the concentration of nickel sulfate hexahydrate. Note that, among nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium, the amounts of cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium in each electroless copper plating bath or electroless copper plating deposit were below the detection limit.
(Step (4))The glass substrate with the electroless copper plating deposit formed thereon was subjected to a second heat treatment (in the air, 150° C., 30 minutes). The deposit after the second heat treatment was evaluated as described below. Table 3 shows the results.
<Metal Amount in Deposit>The amounts of the metals in the deposit were measured using an inductively coupled plasma (ICP) emission spectrometer.
<Evaluation of Appearance of Deposit>The appearance of the deposit was evaluated by visual observation in terms of uniformity using the following criteria.
-
- Excellent: The appearance is uniform.
- Good: The appearance is almost uniform but partly non-uniform.
- Poor: The appearance is non-uniform.
The adhesion of the plating deposit was evaluated by making a 10-mm-wide cut in the glass substrate provided with the plating deposit using a box cutter, peeling the electrolytic copper plating deposit using a tensile testing machine (AGS-X available from Shimadzu Corporation), and measuring the peel strength (i.e., the peel strength of the metal oxide layer to the glass substrate). The adhesion was evaluated using the following evaluation criteria. A higher peel strength index is considered better adhesion. Table 3 shows the results.
-
- Excellent: The peel strength index is 2350 or higher.
- Good: The peel strength index is at least 1566 but lower than 2350.
- Fair: The peel strength index is at least 783 but lower than 1566.
- Poor: The peel strength index is lower than 783.
Here, the peel strength index is an index relative to the peel strength of Comparative Example 1 taken as 100.
Table 3 shows that, in the electroless copper plating deposits of the examples, each of which was formed on a metal oxide layer formed on a surface of a glass or ceramic material, particularly a glass material, and each of which had a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium of 0.1% by mass or more, the metal oxide layer can exhibit good peel strength to the glass or ceramic material, particularly glass material.
Claims
1. An electroless copper plating deposit, formed on a metal oxide layer formed on a surface of a glass or ceramic material, the electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
2. The electroless copper plating deposit according to claim 1,
- wherein the combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium is 1.1% by mass or more.
3. The electroless copper plating deposit according to claim 1,
- wherein the combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium is 1.1 to 4.0% by mass.
4. An electroless copper plating bath, having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1 mmol/l or more.
5. The electroless copper plating bath according to claim 4 for use in forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material.
6. The electroless copper plating bath according to claim 4 for use in forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material, the electroless copper plating deposit having a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
7. A method of producing an electroless copper plating deposit, the method comprising forming an electroless copper plating deposit on a metal oxide layer formed on a surface of a glass or ceramic material using the electroless copper plating bath according to claim 4.
8. The method of producing an electroless copper plating deposit according to claim 7,
- wherein the electroless copper plating deposit has a combined amount of nickel, cobalt, gold, silver, platinum, bismuth, antimony, tungsten, ruthenium, rhodium, lead, tellurium, iron, manganese, titanium, and vanadium that is 0.1% by mass or more.
Type: Application
Filed: Feb 4, 2026
Publication Date: Aug 6, 2026
Applicant: C.Uyemura & Co., Ltd. (Osaka)
Inventors: Hisamitsu Yamamoto (Osaka), Tomoharu Nakayama (Osaka), Shinichiro Yoshida (Osaka), Kanji Matsumoto (Osaka)
Application Number: 19/529,995
