JPH0314915B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to a copper foil for printed circuits and a method for manufacturing the same, and more specifically, when this copper foil is bonded to a base material to form a copper-clad laminate, its adhesive properties before and after high-temperature heat treatment are The present invention relates to a copper foil for printed circuits that has improved hydrochloric acid resistance and oxidation resistance, and a method for manufacturing the same. [Conventional technology and its problems] Recently, as printed circuits have become more dense, copper foil used for printed circuits has characteristics such as excellent peel strength with the base material, solder resistance, and chemical resistance. In addition, even after bonding a base material using an adhesive such as glass-epoxy resin and laminating it by heating and pressing, it can be heated at a high temperature such as 180℃ for 48 hours. , the property of still having good peel strength with the base material is required. Conventionally, as one method of improving the heat resistance of copper foil for printed circuits, a method of galvanizing the copper foil has been known. Zinc has excellent anti-corrosion properties and is particularly effective in improving oxidation resistance under high temperatures.However, on the other hand, it is not practical in terms of hydrochloric acid resistance, which is one of the properties required in the printed circuit manufacturing process. I can't say it's on target. Furthermore, in order to improve the antirust ability of copper foil, there is also a method of forming a thin chromium film on the surface of the copper foil by immersing the copper foil in an aqueous solution of hexavalent chromium salt or subjecting it to cathode treatment. However, when printed circuit boards made from copper foil manufactured using this method are used under harsh conditions, especially at high temperatures, the adhesive properties and oxidation resistance are poor, and there is currently much room for improvement. It is. Furthermore, Japanese Patent Publication No. 58-7077 discloses a heat-resistant copper foil for printed circuits. The copper foil for printed circuits disclosed herein has a thin film of zinc or a mixture of zinc oxide and chromium oxide formed on at least one surface of the copper foil. The manufacturing process of this copper foil for printed circuits includes, for example, a step of electrodepositing dendritic copper on the surface of the copper foil using a copper sulfate electroplating bath, and forming a thin layer of zinc or the like on the surface of the deposited copper. These processes are usually configured as consecutive processes using the same processing equipment. Therefore, after the completion of the electrodeposition process, in the next process, a thin layer of zinc or other material is formed using an alkaline bath, and if the cleaning solution is combined with the wastewater from the electrodeposition process and flows into the drain, the water in the drain is Since copper oxide tends to accumulate, it is necessary to install separate drains for each waste liquid, and large amounts of water are required to wash and remove residual alkaline components on the surface of the copper foil that has formed a thin layer of zinc, etc. Therefore, the waste liquid treatment cost becomes a large proportion of the manufacturing cost. Moreover, although this copper foil has oxidation resistance at high temperatures, it does not basically improve the chemical resistance of zinc itself, so printed circuit boards are manufactured using this copper foil. Hydrochloric acid resistance is not good. Furthermore, Japanese Patent Publication No. 56-20718 discloses a copper foil in which a zinc layer containing tungsten and/or molybdenum is formed on the surface to be joined. However, looking at the examples of this copper foil production method, it is clear that this method uses an extremely highly concentrated zinc sulfate aqueous solution, so in the copper foil washing process, the zinc sulfate that adheres to the copper foil after treatment is removed. It is unavoidable that an extremely large amount of water is consumed to remove the solution, and waste of zinc sulfate and the like due to drag-out is unavoidable. Therefore, not only is this method extremely uneconomical, but the resulting copper foil also has insufficient hydrochloric acid resistance during the production of printed circuit boards. [Problems to be Solved by the Invention] The present invention provides a print that, when made into a copper-clad laminate, has outstanding peel strength from the base material before and after high-temperature heat treatment, and oxidation resistance at high temperatures. The purpose of this invention is to provide a copper foil for circuits and a manufacturing method that can continuously mass produce it. [Means for Solving the Problems] The structure of the copper foil for printed circuits of the present invention includes a copper foil, a molybdenum thin film containing zinc or zinc oxide formed on at least one surface of the copper foil, It is characterized by comprising a chromate-treated film formed on the molybdenum thin film and a silane coupling agent-treated film formed on the chromate-treated film. Step of immersing the copper foil in an electroplating bath made by dissolving zinc or zinc salt to perform electroplating treatment (first step); immersing the obtained treated copper foil in a chromate treatment solution or subjecting it to cathode treatment. Process (second process);
Then, the method is characterized by comprising a step of immersing it in a silane coupling agent treatment liquid and then drying it (third step). [Specific Description] The copper foil used in the copper foil for printed circuits of the present invention may be any of electrolytic copper foil, rolled copper foil, etc., and is not particularly limited. Moreover, there is no particular limitation regarding the thickness of the copper foil. Usually, it is 10 μm, 18 μm, 35 μm, etc. The surface to be bonded to the base material is preferably roughened in advance and dendritic copper is electrodeposited thereon using, for example, a copper sulfate electroplating bath. In the copper foil for printed circuits of the present invention, first, a molybdenum thin film containing zinc or zinc oxide is formed on at least one surface of the above-described copper foil. The zinc or zinc oxide mentioned here is mixed in the molybdenum thin film during electroplating, and specifically includes metal zinc, zinc oxide, zinc hydroxide, and the like. The above molybdenum thin film has a molybdenum content of
10~250μg/dm ² , zinc content 10~250μ
g/dm ² . If the molybdenum content is less than 10 μg/dm ² , the hydrochloric acid resistance of the resulting copper foil begins to deteriorate, which is undesirable;
If it exceeds g/dm ² , the effect of improving the adhesion properties with the substrate and the oxidation resistance decreases, which is not preferable. On the other hand, when the zinc content is less than 10 μg/dm ² , the effect of the obtained copper foil on improving the adhesive properties with the base material and the oxidation resistance decreases,
Moreover, if it exceeds 250 μg/dm ² , hydrochloric acid resistance begins to deteriorate, which is not preferable. In particular, a thin film having a molybdenum content of 50 to 150 μg/dm ² and a zinc content of 50 to 150 μg/dm ² is suitable. This molybdenum thin film is formed as follows (first step). First, prepare an electroplating bath. The electroplating bath used is an aqueous solution containing molybdate ions and in which zinc or zinc salt is dissolved. As a source of molybdate ions, for example, Na ₂ MoO ₄ .
2H ₂ O, K ₂ MoO ₄ , (NH ₄ ) ₆ Mo ₇ O ₂₄・4H ₂ O, and sources of zinc salts include:
For example, ZnSO ₄ 7H ₂ O, ZnCl ₂ , Zn
(CH ₃ COO) ₂・2H ₂ O can be raised. An electroplating bath is constructed by dissolving a predetermined amount of each of these ion sources in water, but the amount of each ion source to be dissolved takes into account the amounts of molybdenum and zinc to be electrodeposited on the copper foil. It can be decided by For example, as a source of molybdate ions.
When Na ₂ MoO ₄ .2H ₂ O is used and ZnSO ₄ .7H ₂ O is used as the zinc ion source, the respective dissolved amounts are 0.5 to 10 g and 0.5 to 10 g per total electroplating bath.
It is preferable that it is in the range of g. The electroplating bath is preferably used by adjusting the pH to 3.0 to 5.0 using an acid solution such as sulfuric acid. PH is
This is because when the pH is lower than 3.0, the amount of zinc deposited increases, and when the pH is higher than 5.0, zinc hydroxide begins to precipitate in the electroplating bath. Next, the copper foil is immersed in this electroplating bath to perform electroplating treatment. Electroplating treatment may normally be carried out at room temperature.
Current density is not particularly limited, but 0.1 to 10A/d
^m2 is preferred. Further, the electroplating time may be 1 to 60 seconds in consideration of the thickness of the molybdenum thin film to be formed. Preferably a range of 1 to 10 seconds is suitable. In the copper foil for printed circuits of the present invention, a chromate-treated film is formed as a second layer on the molybdenum thin film formed in the first step. This chromate treatment film is formed to increase the rust prevention properties of the copper foil and to form an adhesive layer with the silane coupling agent in the next process. This chromate treatment film is made by treating the copper foil obtained in the first step with an aqueous solution containing hexavalent chromium ions, such as Na ₂ Cr ₂ O ₇ .2H ₂ O,
It is formed by simply immersing it in an aqueous solution of CrO ₃ or by cathodic treatment (second step). The concentration of the chromate treatment solution is 0.5 per electroplating solution.
It is preferably in the range of ~10g. It is preferable to adjust the pH of the electroplating bath to 3.0 to 6.0 using an acid solution such as sulfuric acid. When the PH is lower than 3.0, the chromium content increases, and the molybdenum thin film containing zinc or zinc oxide on the surface of the copper foil obtained in the first step dissolves and decreases.
When the value is higher than 6.0, there is a drawback that chromium hydroxide begins to precipitate in the electroplating bath and adheres to the copper foil. In addition, the bath temperature may be room temperature for both cathodic treatment and immersion treatment, and the current density is as follows:
Conditions of 0.1 to 10 A/dm ² and a treatment time of 1 to 60 seconds, including the case of immersion treatment, may be adopted. Preferably, the time may be in the range of 3 to 10 seconds. On the other hand, regarding the chromium content, the chromium content is preferably in the range of 10 to 150 μg/dm ² . If the chromium content is less than 10μg/ ^dm2 ,
The bonding properties with the silane coupling agent layer in the next step will be insufficient, and the effect of improving adhesive strength will be diminished. If the chromium content exceeds 150μg/ ^dm2 ,
The effect is similarly diminished for the same reasons as above. Next, the copper foil for printed circuits of the present invention is manufactured by forming a silane coupling agent treated film as a third layer on the chromate treated film obtained in the second step. This silane coupling agent-treated film is a component that contributes to improving the adhesive properties between the chromate-treated film present as an underlying layer and the substrate to be bonded. The silane coupling agent treated film can be obtained by immersing the copper foil on which the chromate treatment film has been formed in the second step in the silane coupling agent treatment solution described below for a predetermined time, then taking it out and drying it (third step). . The silane coupling agent to be used is
Any of those described in Japanese Patent No. 55-162367 can be used. The silane coupling agent has the following formula: YRSiX ₃ (wherein, Y
is vinyl group, amino group, diamino group, chloro group,
A functional group that reacts with a polymer, such as an epoxy group, a mercapto group, or a methacryloxy group; R is a bonding group containing a chain or cyclic hydrocarbon group that connects the above Y and Si; X is a chloro group, (represents a hydrolyzable group that bonds with Si, such as a methoxy group or an ethoxy group). Of these,
γ-Aminopropyltriethoxysilane, N-2
Typical examples include -aminoethyl-3-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane. The reason why this silane coupling agent enhances the adhesion between the chromate-treated film existing as an underlying layer and the base material is not yet fully elucidated, but Y in the above general formula It is thought that X, which is a hydrolyzable group, contributes to improving adhesion by improving wetting, improving surface roughness, improving compatibility, and forming covalent bonds. If it undergoes disassembly,
As shown in the following formula, silanol and H _X are formed, and this reaction product is thought to provide adhesion to the chromate-treated membrane. YRSiX ₃ +3H ₂ O→YRSi(OH) ₃ +3H ₂ O The concentration of the silane coupling agent treatment liquid used is in the range of 0.001 to 5% by weight, preferably 0.1 to 3% by weight.
The immersion time may be within a range of % by weight, and the immersion time may be 60 seconds or less. It may be 10 to 30 seconds. The copper foil for printed circuits of the present invention is manufactured by successively passing through the three steps described above. If the order of these three steps changes or if any one step is missing, the objective of the present invention, which is to improve the adhesive properties between the copper foil and the base material before and after high-temperature heat treatment, and to improve the oxidation resistance. It is difficult to achieve the effect of improving hydrochloric acid resistance. [Embodiments of the invention] Example 1 Concentration of Na ₂ MoO ₄ 2H ₂ O 1 g/, ZnSO ₄ .
A copper foil with a thickness of 18 μm was immersed in an electroplating bath with a concentration of 2 g of 7H ₂ O and a pH adjusted to 4 with sulfuric acid, at a current density of 0.3 A/dm ² , a current application time of 5 seconds, and a bath temperature of room temperature. Electroplated. After thoroughly washing the treated copper foil after the first step, it was treated with sulfuric acid at a concentration of 5 g/Na ₂ Cr ₂ O _{7.2H 2} O.
It was immersed in an aqueous solution at room temperature adjusted to pH 5, and cathodic treatment was performed for 5 seconds at a current density of 0.5 A/dm ² using the copper foil as a cathode. Next, after thoroughly rinsing the treated copper foil with water,
It was immersed in an aqueous solution of γ-aminopropyltriethoxysilane at a concentration of 0.3% by weight for 10 seconds at room temperature. After removing the copper foil, heat it at a temperature of 100 to 110℃ for about 5 minutes.
After drying for a minute, a copper foil for printed circuits was produced in which a thin molybdenum film, a chromate-treated film, and a silane coupling agent-treated film were laminated in this order. Example 2 The concentration of Na ₂ MoO ₄・2H ₂ O in the first step was
The concentration of ZnSO ₄ 7H ₂ O was 0.5 g/, the current density was 0.1 A/dm ² , the current application time was 3 seconds, and the chromate treatment in the second step was a dipping treatment. A copper foil for printed circuits was produced in the same manner as in Example 1 except for heating. Example 3 The concentration of Na ₂ MoO ₄・2H ₂ O in the first step was
2.0 g/, the concentration of ZnSO ₄ 7H ₂ O was 4.0 g/, the current density was 1.0 A/dm ² ,
The silane coupling agent used in the third step was N-2.
A copper foil for printed circuits was produced in the same manner as in Example 1, except that -aminoethyl-3-aminopropyltrimentoxysilane was used. Comparative Example 1 An aqueous solution of Na ₂ Cr ₂ O ₇・2H ₂ O with a concentration of 5 g/was adjusted to pH 5.0 with sulfuric acid, and then a 18μ thick solution was added to the aqueous solution.
A copper foil of 500 m is immersed in the copper foil, cathode treated at room temperature with a current density of 0.5 A/dm ² and a current application time of 5 seconds. After taking it out, it is thoroughly washed with water and dried at a temperature of 100 to 110°C for 5 minutes. A comparative example sample was manufactured in which a chromate treatment film was formed on the surface of copper foil. Comparative Example 2 A copper foil with a thickness of 18 μm was immersed in an alkaline zinc electroplating bath consisting of 5 g of ZnSO ₄ 7H ₂ O and 40 g of NaOH at a current density of 0.5 A/dm ² and a current application time of 5 seconds.
After electroplating at room temperature, the copper foil was thoroughly washed with water and dried at a temperature of 100 to 110° C. for about 5 minutes to produce a comparative sample in which a zinc film was formed on the surface of the copper foil. Comparative example 3 ZnSO ₄・7H ₂ O5g/, Na ₂ Cr ₂ O ₇・2H ₂ O3
A copper foil with a thickness of 18 μm was immersed in an alkaline zinc-chromium electroplating bath consisting of
After electroplating at room temperature with a current density of 0.3A/dm ² and a current application time of 5 seconds, the copper foil was thoroughly washed with water.
A comparative sample having a zinc-chromium film formed on the surface of the copper foil was prepared by drying at a temperature of 100 to 110° C. for about 5 minutes. Comparative example 4 Concentration of Na ₂ MoO ₄・2H ₂ O 1.5 g/, ZnSO ₄・
Concentration of 7H ₂ O 220g/, CH ₃ COONH ₄ 1.5g/
A copper foil with a thickness of 18 μm was immersed in an electroplating bath adjusted to pH 2.5 at a current density of 0.3 A/dm ² and a current flow time of 5.
After electroplating at a bath temperature of 30°C,
This was thoroughly washed with water. Next, add this copper foil.
After immersing in a chromate treatment solution containing Na ₂ Cr ₂ O ₇ .2H ₂ O at a concentration of 5 g/pH 5 and cathodic treatment using the copper foil as a cathode at a current density of 0.5 A/dm ² for 5 seconds,
The sample was thoroughly washed with water and dried for about 5 minutes at a temperature of 100 to 110°C to produce a comparative sample in which a zinc-molybdenum thin film and a chromate-treated film were laminated in this order. For each of these specimens, the components of each thin film formed on the rough surface side of the copper foil were measured using an atomic absorption spectrophotometer, and the amount of metal adhesion was calculated as μg/dm ² amount. As described above, a glass epoxy resin-impregnated base material was bonded to the rough side of seven types of copper foils at a temperature of 160℃ and a pressure of 100Kg/
Heat and pressure treated at cm ² for 40 minutes to a thickness of 250 mm (length) and 250 mm (width).
A test piece of 1.6 mm copper-clad laminate was manufactured. Next, the peel strength, salt oxidation resistance, and oxidation resistance of each of these specimens were measured according to the following specifications, and the results are collectively shown in the table. (1) Peel strength Peel strength before heat treatment: At room temperature
Compliant with JISC-6481 method Peel strength after heat treatment: 180
Peel strength was measured in accordance with JISC-6481 after being kept in a constant temperature bath at ℃ for 48 hours (2) Hydrochloric acid resistance Peel strength at room temperature was A, 6N at room temperature.
When the peel strength after being immersed in hydrochloric acid for 1 hour is B, it is expressed as a deterioration rate calculated from (A-B)/A x 100 (%). (3) Oxidation resistance Visually judge the degree of discoloration when the copper-clad laminate is kept in a constant temperature bath at 180℃ for 30 minutes. 〇 - No discoloration, △ - Slight discoloration, × - Significant discoloration (and color)

[Table] [Effects of the Invention] As is clear from the above description, the copper foil for printed circuits of the present invention has a high peel strength with respect to the base material before and after heat treatment in a copper-clad laminate made from the copper foil. It is large, has excellent hydrochloric acid resistance and oxidation resistance, and
The manufacturing method requires a low concentration of the chemical solution used, so the amount of water consumed during washing can be small.
Moreover, since it can be processed continuously, it has a great mass production effect, and its industrial value is great.

Claims (1)

[Claims] 1. A copper foil, a molybdenum thin film containing zinc or zinc oxide formed on at least one surface of the copper foil, a chromate-treated film formed on the molybdenum thin film, A copper foil for printed circuits comprising a silane coupling agent treated film formed on a chromate treated film. 2 The molybdenum thin film contains molybdenum 10 to 250μ
g/ ^dm2 , zinc 10-250μg/ ^dm2 ,
In addition, the chromate treatment film has a chromium content of 10 to 150μg/d.
The copper foil for printed circuits according to claim 1, which is composed of m ² . 3 A process of electroplating by immersing the copper foil in an electroplating bath containing molybdate ions and dissolving metallic zinc or zinc salt; immersing the resulting treated copper foil in a chromate treatment solution or using a cathode A method for producing copper foil for printed circuits, comprising the steps of: applying a treatment; and then immersing it in a silane coupling agent treatment solution and then drying it. 4. The method for producing copper foil for printed circuits according to claim 3, wherein the electroplating bath and the chromate treatment liquid are acidic liquids.