JPH06169170A - Copper foil for printed circuit and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To establish the bonded surface roughening technology of the copper foil for printed circuit posing no environmetal problem at all while giving sufficient bond strength onto a resin substrate causing no trouble of dusting. CONSTITUTION:The copper foil for printed circuit is provided with roughened surfaces 3 comprising multiple protrudent copper electrodeposit containing germanium on the bonded surface of a copper foil 1, a copper plating layer 4 preferably covering the roughened layers 3, a treated layer 5 comprising exceeding one or two kinds of metals or alloys selected from the groups comprising copper, chrome, iron, cobalt and zinc as well as a rust resisting layer 6 covering the treated layer 5. At this time, 0.001-5g/l of germanium is to be contained in acid copper electrolytic bath. Through these procedures, round copper electrodeposit with the dendrite development satisfactorily suppressed can be formed thereby enabling the bond strength to be increased as well as such problems in electrical characteristics and dusting to be solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil for printed circuits and a method for producing the same, and in particular, germanium is contained on the adhered surface of the copper foil in order to enhance the adhesive strength between the copper foil and the resin substrate. The present invention relates to a printed circuit copper foil having a roughening treatment layer formed of a large number of protrusion-shaped (granular or nodular, hereinafter simply referred to as protrusion) copper electrodeposits, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a printed circuit copper foil is laminated and adhered to a base material such as a synthetic resin under high temperature and high pressure, and then a predetermined circuit pattern is screen-printed with a resist to form a target circuit. An etching process is performed using an etching solution such as a cupric chloride solution to remove unnecessary portions. Finally, the required elements are soldered to form various printed circuit boards for electronic devices. Quality requirements for copper foils for printed wiring boards differ between the adhered surface (roughened surface) to be adhered to the resin base material and the glossy surface.

The requirements for the roughened surface to which the present invention relates are mainly that the peeling strength from the base material is sufficient even after high temperature heating, wet treatment, soldering, chemical treatment, etc. (peeling strength), There is no oxidative discoloration during storage (anti-rust property), lamination with a base material, no so-called laminated stain that occurs after etching (hydrochloric acid resistance), and no powder drop during etching (prevention of powder drop). Above all, having a sufficiently high peeling strength is the most important basic matter of the surface to be adhered.

In order to increase the adhesive strength between the copper foil and the resin substrate, a roughening treatment layer composed of a large number of protruding copper electrodeposits is formed on the adhered surface of the copper foil. When the electrolytic copper foil is subjected to a roughening treatment, the green foil itself already has a convex portion, and a large number of protruding copper electrodeposits are electrodeposited near the top of the convex portion to form a convex portion. It will be further enhanced.

As an effective roughening treatment, Japanese Patent Publication No. 54-38
No. 053, Japanese Examined Patent Publication No. 53-39327 and the like describe electrolyzing in an acidic copper electrolytic bath containing arsenic, antimony, bismuth, selenium or tellurium around a limiting current density. Practically, arsenic acid is often added to the electrolytic bath. As a result, a large number of protruding copper electrodeposits are formed on the convex portions of the raw foil, which increases the adhesive strength and is effective as a roughening treatment method.

[0006]

However, when arsenic is involved, arsenic is contained in the copper electrodeposit at several hundreds of p during electrolysis.
Since pm is taken in, the arsenic present during the recycling of the copper foil or other processing and the disposal of the etching solution in which arsenic is eluted during etching becomes a serious environmental and health problem.
As a roughening treatment method that does not include such toxic elements, a method using a bath to which a small amount of benzoquinoline is added is used (Japanese Patent Publication Sho 56).
No. 41196), molybdenum, vanadium, or a bath containing both of them (Japanese Patent Publication No. 62-56677 and Japanese Patent Publication No. 62-56678), or roughening treatment by pulse plating (Japanese Patent Laid-Open No. 63-17597). JP-A-58-16
No. 4797) has been proposed, but it is not always sufficient in terms of peeling strength, powder falling and the like.

An object of the present invention is to roughen the adhered surface of a copper foil for a printed circuit without causing environmental problems, yet exhibiting sufficient adhesive strength with a resin substrate and causing no powder drop during etching. It is to establish processing technology.

[0008]

Means for Solving the Problems As a result of studies aimed at solving the problems, the inventor of the present invention used a copper electrolytic bath containing germanium ions to form a large number of protruding copper electrodeposits on the adhered surface of a copper foil. When a roughening layer is formed, dendrites (dendritic crystals) are suppressed and the rounded projections are electrodeposited well, the adhesion strength between the copper foil and the resin substrate is improved, and powder drop is prevented. We came to find it useful to avoid. Based on this finding, the present invention provides (1) a copper foil for a printed circuit, comprising a roughening treatment layer composed of a large number of protruding copper electrodeposits containing germanium on the adhered surface of the copper foil. It is provided.

Further, it is possible to further form a treatment layer on the roughening treatment layer in the conventional manner. From this viewpoint, the present invention provides (2) a large number of projections containing germanium on the adhered surface of the copper foil. A roughening treatment layer made of a copper electrodeposit, and a treat comprising at least one metal or alloy selected from the group consisting of copper, chromium, nickel, iron, cobalt and zinc, which coats the roughening treatment layer. And a roughening treatment layer comprising a large number of projecting copper electrodeposits containing germanium on the adhered surface of the copper foil for printed circuit, and the roughening treatment layer. Copper, chrome, nickel to coat
A copper foil for a printed circuit, comprising a treat layer made of one or more kinds of metals or alloys selected from the group consisting of iron, cobalt and zinc, and a rust preventive layer covering the treat layer. I will provide a.

Further, as a method for producing a copper foil for a printed circuit, (4) a large number of protruding copper electrodeposits are formed on the adhered surface of the copper foil by electrolyzing in an acidic copper electrolytic bath using the copper foil as a cathode near the limiting current density. In the method for producing a copper foil for a printed circuit, which comprises forming a roughened layer, the method for producing a copper foil for a printed circuit, characterized in that germanium ions are present in an electrolytic bath in an amount of 0.001 to 5 g / l, and ( 5) It is necessary to electrolytically form a treat layer made of one or more kinds of metals or alloys selected from the group consisting of copper, chromium, nickel, iron, cobalt and zinc on the formed roughening layer by electrolysis. According to the above, there is provided a method for producing a copper foil for a printed circuit as described above, which is characterized by further performing anticorrosion treatment.

[0011]

According to the present invention, 0.001 to 5 g / l of germanium ions are present in the acidic copper electrolytic bath to form the roughening treatment layer, so that the protruding copper electrodeposit contains a small amount of germanium. Also, it suppresses the generation of nuclei during electrodeposition of copper, suppresses the formation of dendrites, and rounds the electrodeposited projection-like particles, which is useful for improving the adhesive strength and prevents powder falling off during etching. If germanium ions are not present in the electrolytic bath, electrolysis near the limiting current will cause the copper electrodeposits to become dendritic and impair rather than improve the bond strength. When powder is removed, fine copper powder remains after the etching process, which may impair the electrical characteristics.

[0012]

EXAMPLES The present invention can be applied to both rolled copper foil and electrolytic copper foil, but in particular to electrolytic copper foil. It is useful for further strengthening individually the large number of protrusions inherent in the electrolytic copper foil. Such a roughening treatment layer is effectively formed by electrolysis before and after the limiting current using a copper electrolytic bath containing a toxic element typified by arsenic as in the past. It presents environmental and health problems due to its inclusion.

FIG. 1 schematically shows an example of a treatment layer on the surface to be adhered of an electrolytic copper foil. Since the surface of the raw foil 1 to be adhered is an electrolytic copper foil, the convex portions 2 are distributed over the entire surface thereof. A roughening process is performed on this raw foil. By the roughening treatment according to the present invention, the roughening treatment layer 3 composed of a large number of protruding copper electrodeposits containing germanium mainly in the vicinity of the top of the convex portion 2 is formed, and the convex portion is strengthened. When a smooth copper foil such as a rolled copper foil is subjected to a roughening treatment, the electrodeposit itself constitutes a protrusion. After this, there are many treatment modes, for example, a thin copper plating layer 4 is formed to prevent the protruding copper electrodeposits from falling off, and chromium, nickel, iron are added to impart post heat resistance and other properties. A metal or alloy such as cobalt and zinc, for example, a treat plating layer 5 such as brass is formed, and finally a rust preventive layer 6 typified by chromate treatment is formed. The copper foil adhered surface thus treated is adhered to a resin substrate or the like. Hereinafter, each step will be described in detail.

The plating conditions of the copper electrolytic bath for roughening treatment according to the present invention are as follows: Cu ion: 5 to 50 g / l H ₂ SO ₄ : 10 to 100 g / l Germanium ion: 0.001 to 5 g / temperature: room temperature to 50 ° C. D _k : 5 to 80 A / dm ² hours: 1 to 30 seconds The concentration of germanium ions to be present in the copper electrolytic bath is appropriately 0.001 to 5 g / l, preferably 0.1. 0
It is 1 to 1 g / l. If the amount added is less than 0.001 g / l, there is not enough effect to increase the adhesive strength, while 5 g / l
Even if it exceeds, the effect is not significantly improved and the economic burden is increased. An oxide or the like can be used as a source of germanium. For example, germanium dioxide or the like is used.

After the above-described roughening treatment, a treat for forming one or more metal layers or alloy layers selected from the group consisting of copper, chromium, nickel, iron, cobalt and zinc on the roughened surface. Treatment is preferred. For example, a thin copper layer is coated over the electrodeposit in order to prevent the protruding copper electrodeposit of the roughening treatment layer from falling off, and a metal layer of chromium, nickel, iron, cobalt or zinc, or a copper layer. Nickel, copper-cobalt, copper-nickel-cobalt, copper-
An alloy layer typified by zinc or the like may be formed (for example,
JP-B-56-9028, JP-A-54-13971,
JP-A-2-292894, JP-A-2-292895
No. 51-35711, 54-6701
No.). Such treated layers serve as determinants of the final properties of the copper foil and as barrier layers.

[0016] For example, in the case of a zinc coating, either zinc electroplating or electroless plating can be performed, but zinc electrolytic operation is more convenient for forming a coating only on one surface of the roughened surface. Further, the electrolysis operation is preferable from the viewpoints of precise control of thickness, thickness uniformity, densification of the adhesion layer, and the like. Zinc electrolysis can be performed using an acidic zinc plating bath represented by a zinc sulfate plating bath or a zinc chloride plating bath, an alkaline zinc plating bath such as a zinc cyanide plating bath, or a zinc pyrophosphate plating bath. A commonly used zinc sulfate bath is sufficient. The preferable zinc electrolysis conditions when using a zinc sulfate bath are as follows. _{ZnSO 4 · 7H 2 O: 50~350g} / l pH ( sulfate): 2.5-4.5 bath temperature: 40 to 60 ° C. Yin electrode: copper cation electrode: zinc or insoluble anode Cathode current density: 0.05 ~0.4A / dm between ^2:00: 10 to 30 seconds of zinc coating amount is preferably set to 15~1500μg / dm ^2, particularly preferably 15~400μg / dm ^2. The amount of zinc coating varies depending on the type of resin substrate at the time of stacking. For example, for phenol resin substrates, 15-60 μg
/ Dm ² , 60-150 for glass epoxy resin substrate
0 Pg / dm ^2, particularly preferably 60~400μg / dm ²
And

As an example of the alloy layer, an electrolytic solution composition and conditions for Cu-Zn treatment are given: NaCN: 10 to 30 g / l NaOH: 40 to 100 g / l CuCN: 60 to 120 g / l Zn (CN) ₂ : 1 to 10 g / l pH: 10 to 13 Temperature: 60 to 80 ° C. D _k : 1 to 10 A / dm ²

Further, preferably, a rust preventive layer is formed on the surface of the treated layer. Any known rustproofing treatment can be applied. The chromate treatment liquid may be any of various treatment liquids currently used, but preferable chromate treatment condition examples are as follows: K ₂ Cr ₂ O ₇ (or Na ₂ Cr ₂ O ₇ , CrO)
₃ ): 0.2 to 20 g / l Acid: phosphoric acid or sulfuric acid, organic acid pH: 1.0 to 3.5 Bath temperature: 20 to 40 ° C. Current density: 0.1 to 0.5 A / dm ² hours: 10-60 seconds anode: lead plates, Pt-Ti plate, stainless steel plate chromium oxide coating weight is sufficient 50 [mu] g / dm ² or less as the amount of chromium, and preferably from 15~30μg / dm ^2. When the amount of chromium exceeds 30 μg / dm ² , the rust preventive power is improved but the etching property is deteriorated.

As a useful rust preventive method, the present applicant has proposed a mixed film treatment of zinc and / or zinc oxide and chromium oxide by electrolytic zinc / chromium treatment (Japanese Patent Publication No. 58-7).
No. 077), many achievements have been made. Furthermore, JP-A-2
No. 294490, for the purpose of preventing the generation of black spots under high temperature and high humidity conditions for a long period of time, a chromium oxide film is formed by immersion chromate treatment, and then zinc and / or zinc oxide is formed by electrolytic zinc / chromium treatment. Forming a mixed film with chromium oxide is disclosed.

Finally, if necessary, a silane treatment for applying a silane coupling agent onto the anticorrosive layer is performed mainly for the purpose of improving the adhesive force between the copper foil and the resin substrate. The coating method may be spraying of a silane coupling agent solution, coating with a coater, dipping, pouring, or the like. For example, Japanese Examined Patent Publication No. 60-15654 describes that the adhesion between the copper foil and the resin substrate is improved by subjecting the rough surface side of the copper foil to a chromate treatment and then a silane coupling agent treatment. . For details, refer to this.

The copper foil coated on the roughened surface in this way is
After processing the glossy surface as necessary, apply an adhesive to the roughened surface and heat press bond to the resin substrate to make a copper clad laminate for printed circuits, and after a predetermined processing operation, as a printed circuit board Be used. As a treatment method for glossy surface, various chemical conversion treatments including chromate treatment, organic agent treatment utilizing chelation reaction with copper, coating treatment of metals or alloys that are baser than copper, etc. Appropriate one is selected.

Thereafter, if necessary, an annealing treatment may be performed for the purpose of improving the ductility of the copper foil.

The copper foil roughened in the copper electrolytic bath containing germanium ions according to the present invention has a uniform treatment,
It showed excellent substrate characteristics without unevenness. That is, when a laminate is prepared from a copper foil and a glass cloth-based epoxy resin, it shows good adhesiveness and heat resistance, and a rounded copper electrodeposit with suppressed dendrite development is formed. It was high and showed good properties without problems such as electrical characteristics of the substrate after etching and powder falling off.

Examples and comparative examples will be shown below.

(Example 1) 100 g of copper sulfate (pentahydrate) /
1, sulfuric acid 100 g / l and germanium dioxide 0.15
An aqueous solution containing g / l was used as an electrolytic bath at 30 ° C., and a current density of 10 A / d was applied to the adhered surface of an electrolytic copper foil having a thickness of 70 μm.
Plated at m ² for 20 seconds. When the copper foil thus obtained was analyzed, the content of germanium with respect to the entire foil was about 5 ppm (the content of Ge in the protruding copper electrodeposit was about 0.03 wt%). An electron micrograph showing the electrodeposition state of the protruding copper electrodeposit on the roughened surface of the obtained copper foil is shown in FIG. Also, heating with glass cloth base epoxy resin
A copper-clad laminate was prepared by pressurizing, and the peel strength and the powder falling property were measured. The results are shown in Table 1.

(Comparative Example 1) As an example containing no additive,
An aqueous solution containing 100 g / l of copper sulfate (pentahydrate) and 100 g / l of sulfuric acid was used as an electrolytic bath at 30 ° C. and had a thickness of 70 μm.
1 with a current density of 20 A / dm ² on the surface to be adhered of electrolytic copper foil of m
Plated for 0 seconds. An electron micrograph showing the electrodeposition state of the protruding copper electrodeposit on the roughened surface of the obtained copper foil is shown in FIG. Further, a copper-clad laminate was prepared by heating and pressurizing with a glass cloth base epoxy resin, and peeling strength and powder falling property were measured. The results are shown in Table 1. In FIG. 3, dendritic electrodeposits are observed.

(Comparative Example 2) As an example containing conventional arsenic, copper sulfate (pentahydrate) 100 g / l, sulfuric acid 100 g / l
An aqueous solution containing 3 g / l of arsenic acid and 30 g of arsenic acid was used as an electrolytic bath, and an adhered surface of an electrolytic copper foil having a thickness of 70 μm was plated at a current density of 20 A / dm ² for 10 seconds. When the copper foil thus obtained was analyzed, the content of arsenic in the entire foil was about 200 ppm (the content of As in the protruding copper electrodeposit was about 1.2 wt%). An electron micrograph showing the electrodeposition state of the protruding copper electrodeposit on the roughened surface of the obtained copper foil is shown in FIG. Further, a copper-clad laminate was prepared by heating and pressurizing with a glass cloth base epoxy resin, and peeling strength and powder falling property were measured. The results are shown in Table 1.

[0028]

[Table 1]

[0029]

The copper foil roughened by the copper electrolytic bath containing germanium ions according to the present invention is uniformly treated and shows excellent substrate characteristics without unevenness. When a laminate is made of copper foil and glass cloth base material epoxy resin, it shows good adhesion and heat resistance, and a rounded electrodeposit with suppressed dendrite formation is formed. Moreover, there is no problem of electrical characteristics of the substrate after etching and powder drop.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a treatment layer on a surface to be adhered of an electrolytic copper foil.

FIG. 2 is an electron micrograph showing the grain structure of the roughened surface of the copper foil obtained in Example 1 (magnification: 3000).
Times).

3 is an electron micrograph showing the grain structure of the roughened surface of the copper foil obtained in Comparative Example 1 (magnification: 3000).
Times).

FIG. 4 is an electron micrograph showing a grain structure of a roughened surface of a copper foil obtained in Comparative Example 2 (magnification: 3000).
Times).

[Explanation of symbols]

 1 Raw Foil 2 Convex 3 Roughening Layer 4 Copper Plating Layer 5 Treating Plating Layer 6 Anticorrosion Layer

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 19, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Copper foil for printed circuit and method for manufacturing the same

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil for printed circuits and a method for producing the same, and in particular, germanium is contained on the adhered surface of the copper foil in order to enhance the adhesive strength between the copper foil and the resin substrate. The present invention relates to a printed circuit copper foil having a roughening treatment layer formed of a large number of protrusion-shaped (granular or nodular, hereinafter simply referred to as protrusion) copper electrodeposits, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a printed circuit copper foil is laminated and adhered to a base material such as a synthetic resin under high temperature and high pressure, and then a predetermined circuit pattern is screen-printed with a resist to form a target circuit. An etching process is performed using an etching solution such as a cupric chloride solution to remove unnecessary portions. Finally, the required elements are soldered to form various printed circuit boards for electronic devices. Quality requirements for copper foils for printed wiring boards differ between the adhered surface (roughened surface) to be adhered to the resin base material and the glossy surface.

The requirements for the roughened surface to which the present invention relates are mainly that the peeling strength from the base material is sufficient even after high temperature heating, wet treatment, soldering, chemical treatment, etc. (peeling strength), There is no oxidative discoloration during storage (anti-rust property), lamination with a base material, no so-called laminated stain that occurs after etching (hydrochloric acid resistance), and no powder drop during etching (prevention of powder drop). Above all, having a sufficiently high peeling strength is the most important basic matter of the surface to be adhered.

In order to increase the adhesive strength between the copper foil and the resin substrate, a roughening treatment layer composed of a large number of protruding copper electrodeposits is formed on the adhered surface of the copper foil. When the electrolytic copper foil is subjected to a roughening treatment, the green foil itself already has a convex portion, and a large number of protruding copper electrodeposits are electrodeposited near the top of the convex portion to further form the convex portion. Will be strengthened.

As an effective roughening treatment, Japanese Patent Publication No. 54-38
No. 053, Japanese Examined Patent Publication No. 53-39327 and the like describe electrolyzing in an acidic copper electrolytic bath containing arsenic, antimony, bismuth, selenium or tellurium around a limiting current density. Practically, arsenic is often added to the electrolytic bath. As a result, a large number of protruding copper electrodeposits are formed on the convex portions of the raw foil, which increases the adhesive strength and is effective as a roughening treatment method.

[0006]

However, when arsenic is involved, arsenic is contained in the copper electrodeposit at several hundreds of p during electrolysis.
Since pm is taken in, the arsenic present during the recycling of the copper foil or other processing and the disposal of the etching solution in which arsenic is eluted during etching becomes a serious environmental and health problem.
As a roughening treatment method that does not include such toxic elements, a method using a bath to which a small amount of benzoquinoline is added is used (Japanese Patent Publication Sho 56).
No. 41196), molybdenum, vanadium, or a bath containing both of them (Japanese Patent Publication No. 62-56677 and Japanese Patent Publication No. 62-56678), or roughening treatment by pulse plating (Japanese Patent Laid-Open No. 63-17597). JP-A-58-16
No. 4797) has been proposed, but it is not always sufficient in terms of peeling strength, powder falling and the like.

An object of the present invention is to roughen the adhered surface of a copper foil for a printed circuit without causing environmental problems, yet exhibiting sufficient adhesive strength with a resin substrate and causing no powder drop during etching. It is to establish processing technology.

[0008]

Means for Solving the Problems As a result of studies aimed at solving the problems, the inventor of the present invention used a copper electrolytic bath containing germanium ions to form a large number of protruding copper electrodeposits on the adhered surface of a copper foil. When a roughened layer is formed, dendrites (dendritic crystals) are suppressed and the rounded projections are well electrodeposited to improve the adhesive strength between the copper foil and the resin substrate and to remove powder. It came to be found to be useful in avoiding. Based on this finding, the present invention provides (1) a copper foil for a printed circuit, comprising a roughening treatment layer composed of a large number of protruding copper electrodeposits containing germanium on the adhered surface of the copper foil. It is provided.

Further, it is possible to further form a treatment layer on the roughening treatment layer in the conventional manner. From this viewpoint, the present invention provides (2) a large number of projections containing germanium on the adhered surface of the copper foil. A roughening treatment layer made of a copper electrodeposit, a copper plating layer covering the roughening treatment layer to prevent the protruding copper electrodeposition from falling off, and copper, chromium, nickel, which coats the copper plating layer. A copper foil for a printed circuit, comprising a treat layer comprising one or more metals or alloys selected from the group consisting of iron, cobalt and zinc, and (3).
A roughening treatment layer comprising a large number of projecting copper electrodeposits containing germanium on the adherend surface of the copper foil, and a copper plating layer coating the roughening treatment layer to prevent the protruding copper electrodeposits from falling off. Coating the copper plating layer and selected from the group consisting of copper, chromium, nickel, iron, cobalt and zinc, 1
Provided is a copper foil for a printed circuit, which has a treat layer made of one or more kinds of metals or alloys, and a rust preventive layer covering the treat layer.

Further, as a method for producing a copper foil for a printed circuit, (4) a large number of protruding copper electrodeposits are formed on the adhered surface of the copper foil by electrolyzing in an acidic copper electrolytic bath using the copper foil as a cathode near the limiting current density. In the method for producing a copper foil for a printed circuit, which comprises forming a roughened layer, the method for producing a copper foil for a printed circuit, characterized in that germanium ions are present in an electrolytic bath in an amount of 0.001 to 5 g / l, and ( 5) After forming a copper plating layer on the formed roughening treatment layer, it is selected from the group consisting of copper, chromium, nickel, iron, cobalt and zinc 1
There is provided a method for producing a copper foil for a printed circuit as described above, characterized in that a treat layer made of one or more kinds of metals or alloys is formed by electrolysis, and if necessary, rustproofing treatment is further performed.

[0011]

According to the present invention, 0.001 to 5 g / l of germanium ions are present in the acidic copper electrolytic bath to form the roughening treatment layer, so that the protruding copper electrodeposit contains a small amount of germanium. Also, it suppresses the generation of nuclei during electrodeposition of copper, suppresses the formation of dendrites, and rounds the electrodeposited projection-like particles, which is useful for improving the adhesive strength and prevents powder falling off during etching. If germanium ions are not present in the electrolytic bath, electrolysis near the limiting current will cause the copper electrodeposits to become dendritic and impair rather than improve the bond strength. When powder is removed, fine copper powder remains after the etching process, which may impair the electrical characteristics.

[0012]

EXAMPLES The present invention can be applied to both rolled copper foil and electrolytic copper foil, but in particular to electrolytic copper foil. It is useful for further strengthening individually the large number of protrusions inherent in the electrolytic copper foil. Conventionally, such a roughening treatment layer is processed by electrolysis before and after the limiting current using a copper electrolytic bath containing a toxic element represented by arsenic. It presents environmental and health problems due to its inclusion.

FIG. 1 schematically shows an example of a treatment layer on the surface to be adhered of an electrolytic copper foil. Since the surface of the raw foil 1 to be adhered is an electrolytic copper foil, the convex portions 2 are distributed over the entire surface thereof. A roughening process is performed on this raw foil. By the roughening treatment according to the present invention, the roughening treatment layer 3 composed of a large number of protruding copper electrodeposits containing germanium mainly in the vicinity of the top of the convex portion 2 is formed, and the convex portion is strengthened. When a smooth copper foil such as a rolled copper foil is subjected to a roughening treatment, the electrodeposit itself constitutes a protrusion. After this, there are many treatment modes. For example, a thin copper plating layer 4 is formed to prevent the protruding copper electrodeposits from falling off, and copper, chromium, nickel are added to impart post heat resistance and other properties. A metal or alloy such as iron, cobalt and zinc, for example, a treat plating layer 5 such as brass is formed, and finally a rust preventive layer 6 typified by chromate treatment is formed. The copper foil adhered surface thus treated is adhered to a resin substrate or the like. Hereinafter, each step will be described in detail.

The plating conditions of the copper electrolytic bath for roughening treatment according to the present invention are as follows: Cu ion: 5 to 50 g / l H ₂ SO ₄ : 10 to 110 g / l Germanium ion: 0.001 to 5 g / l temperature: room temperature to 50 ° C. D _k : 5 to 80 A / dm ² hours: 1 to 30 seconds The germanium ion concentration in the copper electrolytic bath is suitably 0.001 to 5 g / l, preferably 0.1. 0
It is 1 to 1 g / l. If the amount added is less than 0.001 g / l, there is not enough effect to increase the adhesive strength, while 5 g / l
Even if it exceeds, the effect is not significantly improved and the economic burden is increased. An oxide or the like can be used as a source of germanium. For example, germanium dioxide or the like is used.

After the roughening treatment as described above, a copper plating layer is formed on the roughened surface, and then one or more kinds selected from the group consisting of copper, chromium, nickel, iron, cobalt and zinc are used. It is preferable to perform a treat treatment for forming a metal layer or an alloy layer. For example, a thin copper plating layer is coated on the electrodeposited material in order to prevent the protruding copper electrodeposited material of the roughening treatment layer from falling off by a known method described in JP-B-62-56677 and the like. Copper, chrome, nickel, iron,
A metal layer of cobalt or zinc or an alloy layer typified by copper-nickel, copper-cobalt, copper-nickel-cobalt, copper-zinc, etc. may be formed (for example, Japanese Patent Publication No. 56-56).
-9028, JP-A-54-13971, JP-A-2-
292894, JP-A-2-292895, JP-B-5
1-35711, Japanese Examined Patent Publication No. 54-6701). Such treated layers serve as determinants of the final properties of the copper foil and as barrier layers.

[0016] For example, in the case of a zinc coating, either zinc electroplating or electroless plating can be performed, but zinc electrolytic operation is more convenient for forming a coating only on one surface of the roughened surface. Further, the electrolysis operation is preferable from the viewpoints of precise control of thickness, thickness uniformity, densification of the adhesion layer, and the like. Zinc electrolysis can be performed using an acidic zinc plating bath represented by a zinc sulfate plating bath or a zinc chloride plating bath, an alkaline zinc plating bath such as a zinc cyanide plating bath, or a zinc pyrophosphate plating bath. A commonly used zinc sulfate bath is sufficient. The preferable zinc electrolysis conditions when using a zinc sulfate bath are as follows. ^{ZnSO 4 · 7H 2 O: 50~350g} / l pH ( sulfate): 2.5-4.5 bath temperature: 40 to 60 ° C. Yin electrode: copper cation electrode: zinc or insoluble anode Cathode current density: 0.05 ~0.4A / dm between ^2:00: 10 to 30 seconds of zinc coating amount is preferably set to 15~1500μg / dm ^2, particularly preferably 15~400μg / dm ²
Is. The amount of zinc coating varies depending on the type of resin substrate at the time of stacking. For example, for phenolic resin substrates, 15-60μ
g / dm ² and 60 to 1 for glass epoxy resin substrate
500 μg / dm ² , particularly preferably 60 to 400 μg
/ Dm ² .

As an example of the alloy layer, an electrolytic solution composition and conditions for Cu-Zn treatment are given: NaCN: 10 to 30 g / l NaOH: 40 to 100 g / l CuCN: 60 to 120 g / l Zn (CN) ₂ : 1 to 10 g / l pH: 10 to 13 Temperature: 60 to 80 ° C. D _k : 1 to 10 A / dm ²

Further, preferably, a rust preventive layer is formed on the surface of the treated layer. Any known rustproofing treatment can be applied. The chromate treatment liquid may be any of various treatment liquids currently used, but preferable chromate treatment condition examples are as follows: K ₂ Cr ₂ O ₇ (or Na ₂ Cr ₂ O ₇ , Cr)
O ₃ ): 0.2 to 20 g / l Acid: phosphoric acid or sulfuric acid, organic acid pH: 1.0 to 3.5 Bath temperature: 20 to 40 ° C. Current density: 0.1 to 0.5 A / dm ² hours : 10 to 60 seconds Anode: Lead plate, Pt-Ti plate, stainless steel plate Chromium oxide adhesion amount is 50 μg / dm ² as chromium amount
The following is sufficient and preferably 15 to 30 μg / dm ^2.
It is said that When the amount of chromium exceeds 30 μg / dm ² , the rust preventive power is improved but the etching property is deteriorated.

As a useful rust preventive method, the present applicant has proposed a mixed film treatment of zinc and / or zinc oxide and chromium oxide by electrolytic zinc / chromium treatment (Japanese Patent Publication No. 58-7).
No. 077), many achievements have been made. Furthermore, JP-A-2
No. 294490, for the purpose of preventing the generation of black spots under high temperature and high humidity conditions for a long period of time, a chromium oxide film is formed by immersion chromate treatment, and then zinc and / or zinc oxide is formed by electrolytic zinc / chromium treatment. Forming a mixed film with chromium oxide is disclosed.

Finally, if necessary, a silane treatment for applying a silane coupling agent onto the anticorrosive layer is performed mainly for the purpose of improving the adhesive force between the copper foil and the resin substrate. The coating method may be spraying of a silane coupling agent solution, coating with a coater, dipping, pouring, or the like. For example, Japanese Examined Patent Publication No. 60-15654 describes that the adhesion between the copper foil and the resin substrate is improved by subjecting the rough surface side of the copper foil to a chromate treatment and then a silane coupling agent treatment. . For details, refer to this.

The copper foil coated on the roughened surface in this way is
After processing the glossy surface as necessary, apply an adhesive to the roughened surface and heat press bond to the resin substrate to make a copper clad laminate for printed circuits, and after a predetermined processing operation, as a printed circuit board Be used. As a treatment method for glossy surface, various chemical conversion treatments including chromate treatment, organic agent treatment utilizing chelation reaction with copper, coating treatment of metals or alloys that are baser than copper, etc. Appropriate one is selected.

Thereafter, if necessary, an annealing treatment may be performed for the purpose of improving the ductility of the copper foil.

The copper foil roughened in the copper electrolytic bath containing germanium ions according to the present invention has a uniform treatment,
It showed excellent substrate characteristics without unevenness. That is, when a laminate is prepared from a copper foil and a glass cloth-based epoxy resin, it shows good adhesiveness and heat resistance, and a rounded copper electrodeposit with suppressed dendrite development is formed. It was high and showed good properties without problems such as electrical characteristics of the substrate after etching and powder falling off.

Examples and comparative examples will be shown below.

(Example 1) 100 g of copper sulfate (pentahydrate) /
1, sulfuric acid 100 g / l and germanium dioxide 0.15
An aqueous solution containing g / l was used as an electrolytic bath at 30 ° C., and a current density of 10 A / d was applied to the adhered surface of an electrolytic copper foil having a thickness of 70 μm.
Plated at m ² for 20 seconds. When the copper foil thus obtained was analyzed, the content of germanium with respect to the entire foil was about 5 ppm (the content of Ge in the protruding copper electrodeposit was about 0.03 wt%). An electron micrograph showing the electrodeposition state of the protruding copper electrodeposit on the roughened surface of the obtained copper foil is shown in FIG. Also, heating with glass cloth base epoxy resin
A copper-clad laminate was prepared by pressurizing, and the peel strength and the powder falling property were measured. The results are shown in Table 1.

(Comparative Example 1) As an example containing no additive,
An aqueous solution containing 100 g / l of copper sulfate (pentahydrate) and 100 g / l of sulfuric acid was used as an electrolytic bath at 30 ° C. and had a thickness of 70 μm.
1 with a current density of 20 A / dm ² on the surface to be adhered of electrolytic copper foil of m
Plated for 0 seconds. An electron micrograph showing the electrodeposition state of the protruding copper electrodeposit on the roughened surface of the obtained copper foil is shown in FIG. Further, a copper-clad laminate was prepared by heating and pressurizing with a glass cloth base epoxy resin, and peeling strength and powder falling property were measured. The results are shown in Table 1. In FIG. 3, dendritic electrodeposits are observed.

(Comparative Example 2) As an example containing conventional arsenic, copper sulfate (pentahydrate) 100 g / l, sulfuric acid 100 g / l
An aqueous solution containing 3 g / l of arsenic and 30 g of arsenic was used as an electrolytic bath, and the adhered surface of an electrolytic copper foil having a thickness of 70 μm was plated at a current density of 20 A / dm ² for 10 seconds. When the copper foil thus obtained was analyzed, the content of arsenic in the entire foil was about 200 ppm (the content of As in the protruding copper electrodeposit was about 1.2 wt%). An electron micrograph showing the electrodeposition state of the protruding copper electrodeposit on the roughened surface of the obtained copper foil is shown in FIG. Further, a copper-clad laminate was prepared by heating and pressurizing with a glass cloth base epoxy resin, and peeling strength and powder falling property were measured. The results are shown in Table 1.

[0028]

[Table 1]

[0029]

The copper foil roughened by the copper electrolytic bath containing germanium ions according to the present invention is uniformly treated and shows excellent substrate characteristics without unevenness. When a laminate is made of copper foil and glass cloth base material epoxy resin, it shows good adhesion and heat resistance, and a rounded electrodeposit with suppressed dendrite formation is formed. Moreover, there is no problem of electrical characteristics of the substrate after etching and powder drop.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a treatment layer on a surface to be adhered of an electrolytic copper foil.

FIG. 2 is an electron micrograph showing the grain structure of the roughened surface of the copper foil obtained in Example 1 (magnification: 3000).
Times).

3 is an electron micrograph showing the grain structure of the roughened surface of the copper foil obtained in Comparative Example 1 (magnification: 3000).
Times).

FIG. 4 is an electron micrograph showing a grain structure of a roughened surface of a copper foil obtained in Comparative Example 2 (magnification: 3000).
Times).

[Explanation of symbols] 1 Raw foil 2 Convex portion 3 Roughening treatment layer 4 Copper plating layer 5 Treat treatment plating layer 6 Anticorrosion layer

Claims (5)

[Claims] 1. A copper foil for a printed circuit, comprising a roughening treatment layer composed of a large number of projecting copper electrodeposits containing germanium on the adhered surface of the copper foil. 2. A roughening treatment layer comprising a large number of projecting copper electrodeposits containing germanium on the adhered surface of a copper foil, and copper, chromium, nickel, iron, cobalt and zinc coating the roughening treatment layer. A copper foil for a printed circuit, comprising a treat layer made of one or more metals or alloys selected from the group consisting of: 3. A roughening treatment layer comprising a large number of projecting copper electrodeposits containing germanium on the surface to be adhered of a copper foil, and copper, chromium, nickel, iron, cobalt and zinc coating the roughening treatment layer. A copper foil for a printed circuit, comprising a treat layer made of one or more kinds of metals or alloys selected from the group consisting of and a rust preventive layer covering the treat layer. 4. A copper for a printed circuit, wherein a copper foil is used as a cathode in an acidic copper electrolytic bath to electrolyze in the vicinity of a limiting current density to form a roughening treatment layer composed of a large number of protruding copper electrodeposits on the adhered surface of the copper foil. A method for producing a copper foil for a printed circuit, characterized in that 0.001 to 5 g / l of germanium ions are present in an electrolytic bath. 5. Copper, chromium, on the roughening layer thus formed
5. A treat layer comprising one or more metals or alloys selected from the group consisting of nickel, iron, cobalt and zinc is formed by electrolysis and further rustproofed if necessary. Manufacturing method of copper foil for printed circuit.