KR20000038812A - Copper foil for printed circuit and production method thereof - Google Patents

Abstract

PURPOSE: A copper foil for a printed circuit and a production method thereof are provided to maintain an adhesive strength between the copper foil and an insulating substrate without performing a processing process of protrusion phase and to have a characteristic of the printed circuit. CONSTITUTION: A film for preventing a diffusion of a copper ion is formed on an upper part of a lusterless face of a copper foil without a processing of protrusion phase. An anticorrosive film is formed in both faces of the copper foil after washing and drying the copper foil formed the preventing film of copper ion diffusion. A film for processing a surface is formed by coating a composition contained an isocyanurate of a formula 1 in a single face or double faces of the copper foil after washing and drying the copper foil formed the anticorrosive film. Thereby the copper foil for a printed circuit is produced. In the formula, an A is expressed as -(CH2)aSi(R)b(OR), an a is 1 or 8, a b is 0 or 3 and an R is an alkyl group of 1 or 8 carbon numbers.

Description

Copper foil for printed circuit and its manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil for a printed circuit and a method of manufacturing the same. More specifically, the present invention relates to a copper foil used for a printed circuit board, while maintaining good adhesion between the copper foil and the insulating substrate without performing a projection process. The present invention relates to a copper foil for a printed circuit having a characteristic of a printed circuit and a manufacturing method thereof.

Printed circuits are widely used as precision control circuits of various electric and electronic communication devices such as televisions, radios, computers, telephone exchanges, and wireless transceivers.

Copper-clad laminates for printed circuits are laminated by heating and pressing copper foil on insulating substrates such as glass-epoxy resin-impregnated substrates, etching them to form a network, and then attaching elements such as semiconductor devices to them. It is made by mounting.

Looking at the conventional manufacturing process of the copper foil for a printed circuit described above, first, a copper foil is obtained through a process of reducing copper ions to a metal by an electrolysis method, and then washed and dried. Then, a projection processing step is performed on the contact surface of the copper foil with the insulating substrate, that is, the non-gloss surface (hereinafter referred to as M surface). Here, the projection process is a process of improving the adhesion between the copper foil and the insulating substrate by forming a projection on the surface of the copper foil using copper oxide powder to increase the surface area of the copper foil and the insulating substrate.

Thereafter, a metal barrier layer is formed on the copper foil that has undergone the roughening step to prevent diffusion of copper ions, and then antirust treatment is performed.

Finally, in order to improve the adhesive force between the copper foil and the insulating substrate, chemical adhesion improving treatment using a chemical binder is performed (Japanese Patent Laid-Open No. 63-183178 and Japanese Patent Laid-Open No. 2-26097). Vinyltriethoxysilane, vinyltris (methoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltri Methoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, etc. This is known.

On the other hand, in recent years, circuits of substrates have been gradually miniaturized, highly integrated, and miniaturized with high quality of printed circuit boards. Therefore, low roughness of the copper foil is required, and the insulating property of the insulating substrate is further emphasized. In order to construct a circuit on the copper foil, an unnecessary part is etched. In this etching process, the loss of the possible circuit must be minimized.

However, the copper oxide powder used in the projection process of the copper foil continues to remain as a residue even after the adhesion process between the copper foil and the insulating substrate. Since this residue is metallic, in particular, when the insulating substrate is thin, there is a problem of lowering the insulating properties between the circuit layers. In addition, in the case of forming a multilayer printed circuit board, the lamination process is performed at a high temperature, and there is a problem of forming a stain in the insulation substrate by reacting the copper oxide existing as a residue during the lamination process and the components of the insulation substrate.

The technical problem to be solved by the present invention is not to prevent the projection process of the copper foil in order to solve the above problems can not only prevent the deterioration of the insulating properties of the insulating substrate due to the etching residue resulting from the projection process. It is to provide a copper foil for a printed circuit and a method of manufacturing the same that can improve the adhesion to the insulating substrate.

1 and 3 are electron scanning micrographs of the surface and cross-section of the copper foil for printed circuit prepared according to Comparative Example 2,

2 and 4 are electron scanning micrographs of the surface and cross-section of the copper foil for printed circuit prepared according to Examples 1 to 2.

In order to achieve the above technical problem, in the present invention, a copper ion diffusion barrier film is formed on the non-gloss surface of the copper foil without a protrusion treatment, and antirust films are formed on both surfaces of the copper foil on which the copper ion diffusion barrier film is formed, and the antirust film is formed. Provided is a copper foil for a printed circuit, wherein a surface treatment film containing an isocyanurate compound of the formula (1) is formed on one or both surfaces of the copper foil.

<Formula 1>

Wherein A is represented by-(CH ₂ ) _a Si (R) _b (OR) _3-b , a is 1 to 8, b is 0 to 3, and R is an alkyl group having 1 to 8 carbon atoms .

The surface treatment film may further include bistrialkoxysilylalkane of formula (2).

(R'O) ₃ Si (B) _C Si (OR ') ₃

In the formula, c is 1 to 8, R 'is an alkyl group having 1 to 8 carbon atoms, and B represents a divalent organic group.

Another technical problem of the present invention is the step of (a) forming a copper ion diffusion barrier layer on the non-gloss surface of the copper foil without a projection process;

(b) washing and drying the copper foil on which the copper ion diffusion preventing film is formed, and then forming a rustproof film on both sides of the copper foil; And

(c) washing and drying the copper foil on which the rust-preventive film is formed, and then coating a composition containing isocyanurate of formula 1 on one or both surfaces of the copper foil to form a surface treatment film. It is made by the manufacturing method of copper foil.

<Formula 1>

Wherein A is represented by-(CH ₂ ) _a Si (R) _b (OR) _3-b , a is 1 to 8, b is 0 to 3, and R is an alkyl group having 1 to 8 carbon atoms .

The copper foil for printed circuits is usually subjected to a projection processing step on the surface (M surface) in contact with the insulating substrate during manufacture. Omitting such a protrusion treatment step significantly lowers the mechanical adhesive properties of the copper foil, causing serious problems such as circuit peeling later. In the present invention, in order to solve this problem, in order to improve the adhesion between the copper foil and the insulating substrate, the surface of the formula (1) on the M surface of the glossy surface (Shiny surface, hereinafter referred to as S surface) and the non-gloss surface (M surface) of the copper foil It is characterized by coating the treatment agent.

<Formula 1>

Wherein A is represented by-(CH ₂ ) _a Si (R) _b (OR) _3-b , a is 1 to 8, b is 0 to 3, and R is an alkyl group having 1 to 8 carbon atoms .

Preferably the surface treatment agent is tris- [3- (trimethoxysilyl) propyl] isocyanurate, tris- [3- (triethoxysilyl) propyl] isocyanurate, tris- [3- (dimethicone) Methoxysilyl) propyl] isocyanurate or tris [-3- (methyldimethoxysilyl) propyl] isocyanurate. Such trialkoxysilylisocyanurates can be synthesized according to various reaction routes. For example, it can be synthesized by quantitative reaction of aminosilane and organic carbonate under basic catalyst, which is disclosed in US Pat. No. 5,218,133.

Hereinafter, a manufacturing method of a copper foil for a printed circuit according to the present invention will be described.

First, copper plating is performed on a to-be-plated material and copper foil is manufactured. Here, the copper plating may use an acidic plating solution or an alkaline plating solution, and the acidic plating solution may include copper sulfate, copper borofluoride, or sulfamic acid copper plating solution, and the alkaline plating solution may be copper cyanide or copper pyrophosphate plating solution.

In the present invention, the acidic copper sulfate plating solution is used in the above-described plating solution. The basic composition of the copper sulfate plating solution is 200 to 450 g / l, preferably 250 to 400 g / l, sulfuric acid 80 to 200 g / l, preferably 90 to 120 g / l. If the copper sulfate concentration is less than 200 g / l, the surface of the electrodeposited copper foil is not only coarse and powder is formed on the surface, but also has low productivity, and when it exceeds 450 g / l, the plating solution is crystallized, which is undesirable. Can not do it. If the sulfuric acid concentration is less than 80 g / l, the electrolytic voltage increases, the manufacturing cost increases, the temperature of the plating liquid rises, the mechanical strength of the copper foil is lowered, and when the sulfuric acid concentration exceeds 200 g / l, the electrolytic voltage is lowered. In addition, the corrosion of the plating solution becomes strong, which causes a problem that the corrosion of the electrode for electrolytic copper is accelerated.

In the preferred plating conditions, the plating liquid temperature is maintained at 50 to 80 ° C., the cathode current density is 75 to 100 A / dm ² , preferably 75 to 85 A / dm ² , and the chlorine ion is 20 to 50 ppm.

Subsequently, a metal barrier is formed on the non-gloss surface of the copper foil by using a metal selected from zinc, nickel, iron, cobalt, molybdenum, tungsten, tin, indium and stainless steel, or two or three alloys thereof. Forming a layer prevents copper ion diffusion.

Next, the copper foil in which the copper ion diffusion prevention film was formed is washed with water and dried. Then, it is immersed in an antirust treatment solution to form an antirust film. The anti-rust treatment solution is not particularly limited, but chromic acid, sodium dichromate, potassium dichromate, chromic anhydride, or the like is used.

The copper foil on which the rust-preventive film was formed was washed with water and dried, and then a composition containing an isocyanurate compound of formula 1 was coated on both surfaces, that is, the M and S surfaces of the copper foil to form a surface treatment film. At this time, the isocyanurate of the formula (1) may be coated directly on the copper foil itself, it may also be coated in a state dissolved in an alcohol solvent or water. When the isocyanurate compound is diluted in a solvent, the concentration of the isocyanurate compound is preferably 0.001-5% by weight, preferably 0.01-1% by weight. If the concentration of isocyanurate is more than 5% by weight, the manufacturing cost of the copper foil is uneconomical, and if it is less than 0.001% by weight, the adhesion between the copper foil and the insulating substrate is not sufficient, which is not preferable.

<Formula 1>

Wherein A is represented by-(CH ₂ ) _a Si (R) _b (OR) _3-b , a is 1 to 8, b is 0 to 3, and R is an alkyl group having 1 to 8 carbon atoms .

The isocyanurate compounds of formula (I) include, in particular, tris- [3- (trimethoxysilyl) propyl] isocyanurate, tris- [3- (triethoxysilyl) propyl] isocyanurate, tris- [ 3- (dimethoxysilyl) propyl] isocyanurate and tris [-3- (methyldiethoxysilyl) propyl] isocyanurate are preferred.

In addition to the isocyanurate, the bistrialkoxysilylalkane compound of the formula (2) may be further added to the surface treatment film. Thus, when the bistrialkoxy silyl alkane compound is used in combination with isocyanurate, not only the antirust effect is improved but also the adhesion between the copper foil and the insulating substrate is further improved.

<Formula 2>

(R'O) ₃ Si (B) _C Si (OR ') ₃

In said formula, c is an integer of 1-8. And B represents a divalent organic group, and specific examples thereof include an alkylene group having 1 to 8 carbon atoms, a divalent aromatic group such as a phenylene group, a divalent aliphatic group containing a siloxane bond, or a divalent aromatic ester. There is a residue. And R 'is an alkyl group having 1 to 8 carbon atoms, and R' is preferably an alkyl group having 1 to 4 among them. This is because these compounds are advantageous in terms of solubility and hydrolysis.

As a specific example of bistrialkoxysilylalkane of Formula 2, bistrimethoxysilylethane (CH ₃ O) Si (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , bistrimethoxysilylpropane (CH ₃ O) Si ( CH ₂ ) ₃ Si (OCH ₃ ) ₃ , bistrimethoxysilylbutane (CH ₃ O) Si (CH ₂ ) ₄ Si (OCH ₃ ) ₃ , bistrimethoxysilylhexane (CH ₃ O) Si (CH ₂ ) ₆ Si (OCH ₃ ) ₃ , bistrimethoxysilylbenzene (CH ₃ O) SiPhSi (OCH ₃ ) ₃ .

Such bistrialkoxysilyl alkanes may be coated directly with the compound itself on copper foil, but it is also possible to coat a composition dissolved in a solvent such as water, ethanol, methanol, methyl ethyl ketone, benzene, or the like. At this time, the concentration of bistrialkoxysilylalkane is preferably 0.001 to 5% by weight, particularly 0.1 to 1% by weight. If the concentration of bistrialkoxysilyl alkane is less than 0.001% by weight, the adhesive force between the copper foil and the insulating substrate is not sufficient, and if it exceeds 5% by weight, the manufacturing cost of the copper foil is increased, which is not economical.

Coating methods for isocyanurate-containing and / or bistrialkoxysilylalkanes-containing compositions include methods for depositing copper foil on isocyanurates and / or bistrialkoxysilylalkanes-containing compositions, isocyanurates and / or bistrialkoxy A method of spraying the silyl alkane-containing composition on the surface of the copper foil, an electrochemical coating method, and the like can be used, but the spray method is a more convenient method.

The copper foil obtained by the above-described method is bonded to an insulating substrate under high temperature and high pressure conditions, thereby completing a copper-clad laminate for a printed circuit. It is preferable that the thickness of the said copper foil is 9-70 micrometers here. Here, when the thickness of copper foil is less than 9 micrometers, a wrinkle arises by the copper foil itself load, and a problem arises in use, and when it exceeds 70 micrometers, there exists a problem that productivity falls.

Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

Copper foil was made using the plating bath containing copper sulfate (400g / l) and sulfuric acid (100g / l) adjusted to 65 degreeC. At this time, the current density was adjusted to 100A / dm ² and the chlorine ion was maintained at 20ppm.

The copper foil thus obtained (thickness: 35 µm) was deposited on a diffusion preventing treatment solution containing sodium cyanide (110 g / l), sodium hydroxide (60 g / l), 90 g / l of cyanide copper, and 5.3 g / l zinc sulfide. A copper ion diffusion barrier was formed on top. At this time, the diffusion preventing treatment solution had a temperature of 50 ° C. and a pH of 11.0-11.5. The current density was maintained at 5 A / dm ² .

Subsequently, the copper foil in which the copper ion diffusion prevention film was formed was washed with water, and dried, and this copper foil was immersed in the antirust process solution containing 10 g / l sodium dichromate, and the antirust film was formed. The temperature of the rust-preventing solution was 25 ° C. and pH was 4.5. Antirust treatment was performed for 2 seconds while maintaining a current density of 0.5 A / dm ² .

Separately, tristrimethoxysilylpropyl isocyanurate (Witscose Ise, trade name: Y11597) was diluted to a concentration of 0.2% in a mixed solvent of methanol and water (60:40 weight ratio) to prepare a bonding promoting treatment solution. .

The copper foil on which the rust preventive film was formed was washed with water and dried, and the copper foil was immersed in the bond promoting treatment solution for 30 seconds, and then dried at 110 ° C. for 5 minutes.

Subsequently, the copper foil subjected to bonding promotion was molded on an epoxy resin-impregnated glass fiber substrate (ANSI grade CEM-1) at 175 ° C. and 50 kgf / cm 2 for 2 hours to complete a copper foil for a printed circuit.

Example 2

Except the bond promoting solution was prepared by dissolving 0.1% of tristrimethoxysilylpropylisocyanurate and 0.2% of bistrimethoxysilylethane (Aldrich) in a mixed solvent of methanol and water (60:40 weight ratio). , The same procedure as in Example 1 was carried out to complete a copper foil for a printed circuit.

Comparative Example 1

A copper foil for printed circuits was completed in the same manner as in Example 1, except that the bonding promoting solution was not coated on the copper foil on which the rust preventive film was formed.

Comparative Example 2

Before forming a copper ion diffusion prevention film on the non-gloss surface of copper foil, after carrying out the process of processing a process using copper oxide, the copper ion diffusion prevention film and the rustproof film were formed in the same manner as in Example 1.

Separately, 3-glycidoxypropyltrimethoxysilane (Witcose Eyes, trade name: A187) was diluted in water to a concentration of 0.2% to prepare a binding promoting treatment solution.

Subsequently, the copper foil on which the rust preventive film was formed was washed with water and dried, and the copper foil was immersed in the bond promoting treatment solution for 30 seconds and then dried at 110 ° C. for 5 minutes.

Then, the copper foil treated for bonding promotion was molded on an epoxy resin-impregnated glass fiber substrate (ANSI grade CEM-1) at 175 ° C. and 50 kgf / cm 2 for 2 hours to complete a copper foil for a printed circuit.

The performance of the copper foil for printed circuits prepared according to Example 1-2 and Comparative Example 1-2 was evaluated as follows.

1) Peeling strength (kgf / ㎠)

Copper foil of width 1mm is measured according to JIS C-6481.

2) Hydrochloric acid resistance (degradation rate after hydrochloric acid treatment) (%)

After immersion in 6N hydrochloric acid solution (25 ° C.) for 1 hour, the change in peel strength between the initial and late deposition phases was measured.

Degradation Rate (%) = (Peel Strength in Initial State-Peel Strength in Terminal State) / (Peel Strength in Initial State) × 100

3) Peel strength after heat treatment (kgf / ㎠)

Peel strength after holding at 225 ° C. for 80 minutes in a hot air circulation dryer is measured.

4) Etchability (resistance after etching) test

An etching solution is prepared by mixing copper chloride 6.6 g / l, hydrochloric acid 69.4 g / l, and hydrogen peroxide 5 g / l aqueous solution. After adjusting the temperature of the obtained etching liquid to 30 degreeC, the copper foil-epoxy resin impregnated glass fiber base laminated board is dipped here for 4 minutes. The resultant is then washed with water to observe the presence of copper residues on the surface of the substrate.

The peel strength of the copper foil for printed circuits prepared according to Examples 1-2 and Comparative Examples 1-2, the degradation rate after hydrochloric acid treatment, the peel strength after heat treatment, and the presence or absence of residue after etching are shown in Table 1 below. .

division Peel Strength (kgf / ㎠) Degradation rate after hydrochloric acid treatment (%) Peel strength after heat treatment (kgf / ㎠) No residue after etching Example 1 1.80 5.2 1.24 none Example 2 1.92 5.5 1.42 none Comparative Example 1 0.78 25.0 0.66 none Comparative Example 2 1.89 6.3 1.40 has exist

Table 1 shows that the copper-clad laminates prepared according to Examples 1 and 2 have significantly improved adhesion between the copper foil and the epoxy resin-impregnated glass fiber substrate after the initial state, hydrochloric acid treatment and heat treatment, as compared with Comparative Example 1. It was able to confirm that the etching property improved compared with the copper foil manufactured according to the comparative example 2.

Meanwhile, the surface state of the copper foil for printed circuits manufactured according to the above Examples and Comparative Examples was examined using an electron microscope, and the results are shown in FIGS. 1 to 4.

1 and 3 are electron scanning micrographs of the surface and cross section of the copper foil prepared according to Comparative Example 2, Figures 2 and 4 are for Examples 1 to 3.

Referring to FIG. 1, it was found that protrusions were formed on the surface of the copper foil, so that adhesion to the insulating substrate was maintained well later.

On the other hand, the copper foil prepared according to Examples 1 to 2, although the protrusion is not formed, the adhesive force with the insulating substrate is rather excellent as compared with the case of Comparative Examples 1 and 2 as can be seen in Table 1 above It was. In addition, as in Comparative Example 2, it was also possible to effectively prevent the insulation characteristics of the printed circuit board from deteriorating due to residues originating from the projections.

The copper foil for printed circuits according to the present invention is excellent in adhesive strength with an insulating substrate without performing a protrusion treatment process on the adhesive surface with the insulating substrate. And the process of manufacturing this copper foil is simplified compared with the conventional case, and productivity is improved.

In addition, when the printed circuit board is manufactured using the above-described copper foil, not only the insulating property of the insulating substrate may be prevented from being lowered due to the residue after etching, but also the etching speed may be improved. As a result, the productivity of the printed circuit board can be improved and the defective rate of the printed circuit board can be significantly reduced.

Claims (7)

A copper ion diffusion barrier film is formed on the non-gloss surface of the copper foil without a protrusion treatment, and an rust preventive film is formed on both sides of the copper foil on which the copper ion diffusion barrier film is formed. The surface treatment film containing an anurate compound is formed, Copper foil for printed circuits characterized by the above-mentioned. <Formula 1> Wherein A is represented by-(CH ₂ ) _a Si (R) _b (OR) _3-b , a is 1 to 8, b is 0 to 3, and R is an alkyl group having 1 to 8 carbon atoms . The isocyanurate compound of Formula 1, wherein the isocyanurate compound of Formula 1 is tris- [3- (trimethoxysilyl) propyl] isocyanurate, tris- [3- (triethoxysilyl) propyl] isocyanu A copper foil for a printed circuit characterized by the above-mentioned, tris- [3- (dimethoxysilyl) propyl] isocyanurate or tris [-3- (methyldiethoxysilyl) propyl] isocyanurate. The copper foil for a printed circuit according to claim 1, wherein the surface treatment film further comprises bistrialkoxysilylalkane of the formula (2). <Formula 2> (R'O) ₃ Si (B) _C Si (OR ') ₃ In the formula, c is 1 to 8, R 'is an alkyl group having 1 to 8 carbon atoms, and B represents a divalent organic group. The copper foil for a printed circuit according to claim 3, wherein B is an alkylene group having 1 to 8 carbon atoms, a divalent aromatic group, a divalent aliphatic group containing a siloxane bond, or a divalent aromatic ester residue. The bistrialkoxysilyl alkane of Formula 2 is bistrimethoxysilylethane, bistrimethoxysilylpropane, bistrimethoxysilylbutane, bistrimethoxysilylhexane or bistrimethoxysilylbenzene. Copper foil for printed circuits, characterized in that. (a) forming a copper ion diffusion barrier layer on the non-gloss surface of the copper foil without protrusion treatment; (b) washing and drying the copper foil on which the copper ion diffusion preventing film is formed, and then forming a rustproof film on both sides of the copper foil; And (c) washing and drying the copper foil on which the rust-preventive film is formed, and then coating a composition containing isocyanurate of formula 1 on one or both surfaces of the copper foil to form a surface treatment film. Copper foil manufacturing method. <Formula 1> Wherein A is represented by-(CH ₂ ) _a Si (R) _b (OR) _3-b , a is 1 to 8, b is 0 to 3, and R is an alkyl group having 1 to 8 carbon atoms . The method of manufacturing a copper foil for a printed circuit according to claim 6, wherein bistrialkoxysilylalkane of the formula (2) is further added to the isocyanurate-containing composition of step (c). <Formula 2> (R'O) ₃ Si (B) _C Si (OR ') ₃ In the formula, c is 1 to 8, R 'is an alkyl group having 1 to 8 carbon atoms, and B represents a divalent organic group.