TWI428065B - Copper foil for printed wiring board and manufacturing method thereof - Google Patents

Description

Copper foil for printed wiring board and method of manufacturing same

The present invention relates to a copper foil for a printed wiring board and a method for producing the same, which are used for forming various conductor patterns such as a wiring pattern of a printed wiring board such as a tape carrier for a semiconductor device, and are used for, for example, a surface of an insulating substrate formed of a polyimide resin film, the printed wiring board copper foil being particularly suitable for performing the pattern position in a manner of seeing through an insulating substrate after pattern formation A printed wiring board or the like for identification.

Conventionally, as a conductor layer for forming a wiring pattern of a printed wiring board and various conductor patterns such as an inner lead portion, a copper foil is generally used.

In particular, in the field of flexible printed wiring boards, a copper foil having a thickness of about several tens of micrometers to 100 μm is laminated on the surface of an insulating substrate formed of a polyimide film. A copper clad substrate for a flexible printed wiring board is formed. Alternatively, an insulating base material layer may be formed by applying a varnish containing polyamic acid as a main component to one side of the copper foil to form a printed wiring board having approximately the same characteristics. Copper clad substrate. In the following, the insulating base material layer formed by applying a varnish to the surface of the copper foil to cure or the like is also referred to as an "insulating substrate for a printed wiring board" (or simply an insulating substrate). In addition, the substrate in which the copper foil is provided on the surface of the insulating base material is collectively referred to as "copper substrate for printed wiring board" (or printed wiring). (metal-clad board for board) (based on the definition of "printed circuit terminology" by the Japan Printed Circuit Industry Association, 2006.6.7, 41.1609 "Metal-coated substrate").

The copper foil and the insulating base material for the printed wiring board require a predetermined adhesiveness (also referred to as surface adhesive strength or surface bondability between the two, and will be expressed only by adhesive strength or adhesiveness), so that it is on the copper foil. In particular, the tacking side is subjected to a roughening treatment.

The copper foil is roughly classified into an electrolytic copper foil and a rolled copper foil according to the manufacturing method thereof, but the same method is used for the roughening treatment. The method includes, for example, a method of attaching fine rice grain-shaped copper (Cu) particles to a surface of a copper foil by so-called baking, or a method of selectively etching a grain boundary by an acid.

For the roughening treatment by baking, in addition to the process of the general copper plating method, a process using an alloy plating method typified by copper (Cu)-nickel (Ni) alloy plating has been proposed. Etc. (Patent Document 1).

As a method for improving the adhesion between the copper foil and the insulating base material for a printed wiring board, in addition to the roughening treatment as described above, the anchor effect is effectively utilized, and the pair remains as the original. The copper foil of the foil is subjected to a surface treatment, that is, a method of providing a metal layer having a high chemical adhesion to an insulating organic compound such as a polyimide resin on the surface of the copper foil. Specifically, a conversion treatment called "chromate treatment" or a silane coupling treatment is a typical example, and these are improving adhesion. At the same time, it also has the effect of anti-rust on the surface of the copper foil.

In the past, the present inventors have developed a technology for developing a copper foil for printed wiring boards having high adhesion to an insulating substrate for a printed wiring board and excellent heat resistance and moisture resistance. Various schemes related to the technique for realizing the copper foil (Patent Documents 2 and 3).

In recent years, the line width and the pitch of the wiring pattern of the flexible printed wiring board tend to be further refined, and further miniaturization of the overall outer dimensions of the printed wiring board has begun to be carried out frequently. A semiconductor device such as an IC (Semiconductor Integrated Circuit; hereinafter abbreviated as IC) is directly mounted on the printed wiring board.

In the mounting of such a semiconductor device, it is necessary to perform alignment for bonding, etc., and the precise adjustment of the position is visually confirmed or optically by identifying a penetrating (so-called "transmission") insulating substrate. A conductor pattern such as a wiring pattern or an internal lead portion is detected.

However, if the wiring pattern or other various conductor patterns are further miniaturized, the accuracy of the positional alignment (positioning) required for welding corresponding thereto is hard to avoid becoming higher. Therefore, the copper foil for printed wiring boards is required to have high visibility when viewed through an insulating substrate (or the possibility of optical recognition by the imaging device in the visible light field, and the following is generally referred to as "visual confirmation". ")" is more than ever.

In order to obtain such high visibility, it is considered that it is effective to apply a blackening treatment (black oxide coating) to the copper foil.

In addition, as a countermeasure other than the above-described blackening treatment, a method has been proposed which is not related to a copper foil for a printed wiring board, but is related to a copper foil for an FPD (planar display) such as a PDP (plasma display panel). Etc., but by forming a cobalt coating on the surface of the copper foil by simple cobalt (Co) plating, it can be seen that the color tone of the surface of the copper foil is gray even before the transparent treatment, and the transparent treatment is substantially Black (Patent Document 4).

[Previous Technical Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 52-145769

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-319286

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2007-119902

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-248221

However, in the blackening treatment, the more the amount of adhesion is, the more easily the blackened particles are detached from the surface of the copper foil. Therefore, if a sufficient blackening treatment is performed in order to obtain high visual confirmation, it is liable to occur. It is called the phenomenon of "dropping powder", and even the problem of the visual confirmation of the conductor pattern is lowered due to such powder drop. In addition, there is a problem in that the powder falling due to the blackening treatment is an important cause of various manufacturing defects such as a defective manufacturing process of the printed wiring board after the process and a defective formation of the wiring pattern and a disconnection failure.

In addition, the color tone of the surface of the copper foil for FPD, which is visually confirmed by the light transmitted through the transparent glass substrate or the like substantially by the backlight or the light of the self-luminous element itself, becomes gray or black. In the aspect of the color, the method proposed in Patent Document 4 for forming a cobalt plating layer by simple cobalt (Co) plating on the surface of a copper foil is a copper foil for a printed wiring board which is the object of the present invention. The technique is completely different from the problem to be solved. Therefore, whether the technique can be applied to improve the visual confirmation of the copper foil when the insulating substrate such as the polyimide film is penetrated is completely unknown.

Further, when the film is processed by such simple cobalt plating, the copper foil for a printed wiring board has a fatal problem in that, in the step of etching (etching) and tin (Sn) plating of the printed wiring board, cobalt is used. It is highly probable that cobalt (Co) is eluted from the plating layer to cause so-called infiltration, peeling, and the like, and further, the reliability of the wiring circuit system of the printed wiring board having a narrow wiring interval is significantly impaired. .

The present invention has been made in view of the above problems, and an object of the invention is to provide a copper foil for a printed wiring board which has high visibility when viewed through an insulating substrate and which is printed, and a method for producing the same In the manufacturing process of the wiring board, there is no possibility of infiltration, peeling, or the like in the case of blackening treatment.

The copper foil for a printed wiring board of the present invention is a copper foil for a printed wiring board which is set to be adhered to the surface of an insulating substrate for forming a conductor pattern on a printed wiring board, and is characterized in that it has a The chroma of the surface of the copper foil for the printed wiring board (the Japanese industrial standard JIS Z8729) c ^* = (a ^*2 + b ^{* 2} ) ^1/2 is 6 or less nickel cobalt Alloy plating.

In addition, the copper foil for a printed wiring board of the present invention is a copper foil for a printed wiring board which is set to be bonded to the surface of an insulating base material in order to form a conductor pattern on a printed wiring board, and is characterized in that it is made of copper. The surface of the original foil formed of (Cu) or a copper-based alloy has a nickel-cobalt alloy plating layer formed of an electroplated coating of an alloy of nickel (Ni) and cobalt (Co), wherein cobalt (Co) The concentration is 20% by mass or more and less than 55% by mass, and the total adhesion amount of nickel (Ni) and cobalt (Co) is 20 μg/cm ² or more and less than 40 μg/cm ² .

The method for producing a copper foil for a printed wiring board according to the present invention is a method for producing a copper foil for a printed wiring board which is set on a surface of a printed wiring board for bonding a conductive pattern to a surface of an insulating substrate. The method comprising: forming a nickel-cobalt alloy plating layer on a surface of a raw foil formed of copper (Cu) or a copper-based alloy, the nickel-cobalt alloy plating layer being formed of an electroplated film of an alloy of nickel (Ni) and cobalt (Co), The concentration of cobalt (Co) is 20% by mass or more and less than 55% by mass, and the total adhesion amount of nickel (Ni) and cobalt (Co) is 20 μg/cm ² or more and less than 40 μg/cm ² ; in the nickel-cobalt alloy a step of forming a zinc plating layer formed of an electroplated film of zinc (Zn) on the plating layer; a step of forming a trivalent chromate treatment layer on the zinc plating layer; and after forming the trivalent chromate treatment layer, The surface of the trivalent chromate-treated layer is coated with an aqueous solution of a decane coupling agent, and dried in a dry atmosphere at a temperature of from 150 ° C to 300 ° C to form a decane coupling treatment layer.

Here, the "copper foil for a printed wiring board which is set to be adhered to the surface of an insulating substrate" means two types of copper foils, for example, in the form of a film or a sheet. A copper foil for a printed wiring board used to form a so-called copper-clad substrate on the surface of the substrate, and a copper foil for a printed wiring board used as follows: by coating on one surface of the copper foil to cure, for example An insulating base material layer is formed of a varnish or the like which is a polyglycine as a main component, and this is an insulating base material, and as a result, a structure in which a copper foil is adhered (adhered) to the surface of an insulating base material is formed.

According to the present invention, the blackening treatment such as penetration and peeling is unlikely to occur, and the chroma of the surface of the copper foil for a printed wiring board which is optically detected by an insulating substrate (based on Japanese Industrial Standards) JIS Z8729)c ^* = (a ^*2 +b ^*2 ) ^1/2 is a nickel-cobalt alloy plating layer of 6 or less, so that the color can be observed when penetrating an insulating substrate typified by polyimine (based on Japanese Industrial Standard JIS Z8729) is a surface in which, for example, a color difference ΔE ^* ab with black is observed to be within 3, as a result, it is possible to realize a copper foil for a printed wiring board which is mounted on a semiconductor chip (semiconductor chip) When the position is aligned, it is sufficiently visually identifiable in a state of so-called penetration observation by an insulating base material, and it is possible to form no penetration or peeling in the manufacturing process of the printed wiring board. The conductor pattern after that.

Hereinafter, a copper foil for a printed wiring board according to the present embodiment, a method for manufacturing the same, and a printed wiring board will be described with reference to the drawings.

The copper foil for a printed wiring board has a laminated structure in which a roughened plating layer 2, a Ni-Co (nickel-cobalt) alloy plating layer 3, and a Zn (zinc) plating layer are sequentially laminated on the surface of the original foil 1. 4. A chromate treatment layer 5 and a decane coupling treatment layer 6 are formed. In order to form a conductor pattern of a printed wiring board, a typical example is used for adhering to an insulating substrate such as a polyimide film. Set the surface of the illustration).

The original foil 1 is a copper foil formed of copper (Cu) or a copper-based alloy. For the original foil 1 itself, a generally rolled copper foil or an electrolytic copper foil which is formed of pure copper or a copper-based alloy for use in a general printed wiring board, a flexible printed wiring board or a semiconductor device can be used. Use a belt carrier, etc.

However, the copper foil for a printed wiring board having the original foil 1 is a conductor for forming a printed wiring board which is particularly required to have moderate mechanical flexibility and bendability such as a flexible printed wiring board or a tape carrier. In the case of the patterned copper foil, from the viewpoint of surface flatness and bending property, it is more preferable to use a rolled copper foil having superior characteristics as compared with the electrolytic copper foil.

The roughened plating layer 2 is provided, for example, on the surface of the original foil 1 for improving the adhesion of the copper foil for the printed wiring board to the insulating base material (improving the fixing effect). The roughened plating layer 2 itself may be a layer formed of a general material manufactured by a general manufacturing method.

The nickel-cobalt alloy plating layer 3 is formed on the roughened plating layer 2 by alloy plating of nickel (Ni) and cobalt (Co), and the concentration of cobalt (Co) is 20% by mass or more and less than 55% by mass, and nickel (Ni) The total adhesion amount to cobalt (Co) is 20 μg/cm ² or more and less than 40 μg/cm ² .

The copper foil for a printed wiring board according to the embodiment of the present invention has a nickel-cobalt alloy plating layer 3 having a material formed by the above-described composition, so that the surface provided on one side of the plating layer 3 is penetrated. The insulating substrate such as the quinone imine resin film substrate is extremely excellent in visual visibility when viewed. At the same time, when the printed wiring board is produced using the copper foil for a printed wiring board, it is possible to avoid the infiltration of cobalt (Co) from the nickel-cobalt alloy plating layer 3, the adhesion, and the like.

In other words, in order to improve the wiring pattern formed by performing pattern processing or the like on the copper foil for a printed wiring board, the penetration of various conductor patterns such as a pad portion or an internal lead wire, such as a polyimide film substrate. It is preferable that the color of the conductor pattern to be visually recognized, that is, the color of the surface on the side opposite to the insulating substrate in the copper foil for a printed wiring board, is preferably the color of the insulating substrate. May be black.

However, the inventors of the present invention conducted various experiments and investigations on the relationship between the color of the surface on the side opposite to the insulating base material and the visual confirmation of the copper foil for a printed wiring board, and the results were investigated. As a result of intensive research and investigation, it was confirmed that the color for visual recognition (or detection in the visible light region) on the surface of the copper foil for printed wiring boards is not necessarily black, but it is visually A color that is identifiable by a gray color, and a color such as khaki or brownish brown which is obtained from a polyimide substrate film substrate as an insulating substrate, can also obtain a good visual appearance similar to that in the case of black. Confirmatory or optically identifiable.

The color of such a conductor pattern refers to the color of the color c ^* = (a ^{* 2} + b ^{* 2} ) ^1/2 defined by Japanese Industrial Standard JIS Z8729 by optically detecting (penetrating) the insulating substrate. 6 or less. Or the color difference ΔE ^* ab of the color and black defined by Japanese Industrial Standard JIS Z8730, which is optically detected by an insulating substrate, is within three.

In addition, in order to obtain the color of the surface which is able to obtain the visually identifiable property, it is confirmed that the nickel-cobalt alloy plating layer 3 of the material (composition) as described above is suitable by various experiments such as the samples of the examples and the comparative examples. (In addition, examination of the experiment using such a sample and the result thereof will be further specifically described in the examples to be described later).

Here, it is basically confirmed that the thickness of the nickel-cobalt alloy plating layer 3 (in other words, the amount of adhesion) is increased, and there is a tendency that the higher the visibility can be obtained. However, it has been confirmed that the total amount of adhesion of nickel (Ni) and cobalt (Co) is not as good as possible, and conversely, if it is too small, there is a tendency that good visibility is not obtained.

In other words, as a suitable numerical range of the total adhesion amount of nickel (Ni) and cobalt (Co) in the nickel-cobalt alloy plating layer 3, it is preferably 20 μg/cm ² or more and less than 40 μg/cm ² .

This is because if the total adhesion amount of nickel (Ni) and cobalt (Co) in the nickel-cobalt alloy plating layer 3 is less than 20 μg/cm ² , it is difficult to obtain a color having high visibility, and if it is 40 μg/cm ² or more, When the copper foil for a printed wiring board is subjected to pattern processing by an etching method to form various conductor patterns including wiring patterns, it is likely that a nickel-cobalt alloy plating layer 3 as an etching residue remains at the non-pattern portion which should be completely removed, and The migration of the circuit system formed by the conductor pattern processed in this pattern is significantly impaired.

Further, the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 is preferably 20% by mass or more and less than 55% by mass.

This is because when a printed wiring board is manufactured using a copper foil for a printed wiring board provided with a nickel-cobalt alloy plating layer 3 containing a large amount of (high-concentration) cobalt (Co) of 55 mass% or more, the printed wiring board is manufactured. In the step, in particular, a step of patterning a copper foil for a printed wiring board by etching or the like to form various conductor patterns, a step of performing half etching after forming the conductor pattern, or a step of performing tin (Sn) plating, or the like, It is highly probable that cobalt (Co) is dissolved from the nickel-cobalt alloy plating layer 3 to be precipitated (dissolved), resulting in a phenomenon called so-called infiltration. In addition, if the concentration of cobalt (Co) is less than 20% by mass, the decrease in the adhesive strength is likely to be remarkable, and the etching property of the entire copper foil for a printed wiring board is also lowered.

For this reason, the total adhesion amount of nickel (Ni) and cobalt (Co) in the nickel-cobalt alloy plating layer 3 is 20 μg/cm ² or more and less than 40 μg/cm ² , and the cobalt concentration is 20% by mass or more. When the amount is less than 55% by mass, the surface color can be obtained with good visibility, and the infiltration of cobalt (Co) contained in the nickel-cobalt alloy plating layer 3 can be suppressed or eliminated, and the non-graphics can be obtained. The mobility of the circuit system due to the residual of the nickel-cobalt alloy plating layer 3 in the portion is lowered.

Here, by performing the pre-roughening treatment in advance, it is possible to suppress the decrease in the adhesive strength even if the cobalt concentration is less than 55 mass%. Further, by appropriately performing a decane coupling treatment or the like, the adhesion strength to the polyimide resin can be enhanced.

The zinc plating layer 4 is formed by performing zinc (Zn) plating on the nickel-cobalt alloy plating layer 3 in order to impart a rust-preventing effect to the copper foil for the printed wiring board.

As the plating process for forming the zinc plating layer 4, a sulfuric acid bath, an alkali zincate bath, a chloride bath or the like can be used. Further, more specific process conditions and the like can be appropriately set in accordance with the rust preventive performance and other various requirements required for the zinc plating layer 4.

However, in the present embodiment, the adhesion amount of the zinc plating layer 4 is preferably less than 3 μg/cm ² . This is because if the adhesion amount of the zinc plating layer 4 formed on the nickel-cobalt alloy plating layer 3, that is, the adhesion amount of zinc (Zn) is 3 μg/cm ² or more, it is likely that the printing is performed by using the copper foil for the printed wiring board. The hydrochloric acid and the electroless tin (electroless tin) plating solution used in the step of the wiring board cause the zinc (Zn) component to be eluted, and the adhesion strength of the printed wiring board copper foil to the insulating base material is lowered.

The chromate treatment layer 5 is formed by performing a chemical conversion treatment called "chromate treatment" on the surface of the zinc plating layer 4. For the chromate treatment, a treatment liquid containing no harmful hexavalent chromium composition should be used in view of its influence on the environment and the human body. Specifically, trivalent chromium is preferably used.

The amount of adhesion of the chromate treatment layer 5 is preferably 2.5 μg/cm ² or less. When the amount of adhesion is more than this, the thickness of the chromate treatment layer 5 is too thick, and the possibility that the adhesion of the copper foil for a printed wiring board to the insulating base material is reduced. high.

The decane coupling treatment layer 6 is formed by performing a decane coupling treatment on the surface of the chromate treatment layer 5 in order to improve the adhesion strength to the surface of the insulating base material formed of an organic compound such as a polyimide resin.

As the decane coupling treatment agent used in forming the decane coupling treatment layer 6, a variety of substances can be used, especially when a polyimide film is used as an insulating substrate, and an amino silane-based system is used. The treatment agent is suitable.

As a method of producing the copper foil for a printed wiring board, first, a roughened plating layer 2 is formed on the surface of the original foil 1 by a roughening plating process.

On the roughened plating layer 2, a nickel-cobalt alloy plating layer 3 is formed by electroplating of an alloy of nickel (Ni) and cobalt (Co), wherein a concentration of cobalt (Co) is 20% by mass or more and less than 55% by mass, and nickel The total adhesion amount of (Ni) and cobalt (Co) is 20 μg/cm ² or more and less than 40 μg/cm ² .

Next, zinc plating is performed on the surface of the nickel-cobalt alloy plating layer 3 with an adhesion amount of preferably less than 3 μg/cm ² to form the zinc plating layer 4.

The chromate formation treatment is performed on the surface of the zinc plating layer 4, and it is preferred to form the chromate treatment layer 5 having a deposition amount of trivalent chromium of 2.5 μg/cm ² or less.

Then, it is preferred to further perform a decane coupling treatment on the surface of the chromate treatment layer 5 using a treatment liquid of an amino decane system, thereby forming a decane coupling treatment layer 6.

Here, in particular, the drying temperature and drying time at the time of forming the decane coupling treatment layer 6 depend on the structure of the apparatus for performing the treatment, the processing speed thereof, and the like, but the drying temperature is preferably a suitable numerical range. The temperature is set to 150 ° C or more and 300 ° C or less, and the drying time is set to 15 seconds or more and 35 seconds or less.

For example, when a device capable of ensuring a drying time of 30 seconds is used, 150 ° C to 200 ° C is the most suitable numerical range for the drying temperature. This is because, although it is more specifically described in the examples, by setting the drying temperature and the drying time in this manner, it is possible to surely obtain sufficient adhesive strength.

In the printed wiring board manufactured by using the copper foil for a circuit board according to the embodiment of the present invention, the conductor pattern formed by patterning the copper foil for the printed wiring board is penetrated by, for example, a polyimide resin. The insulating substrate such as a film is visually confirmed (or optically detected), and the color defined by Japanese Industrial Standard JIS Z8730 has a color difference ΔE ^* ab of, for example, 3 or less, and the color of the insulating substrate is added. The visual confirmation of the conductor pattern can be made extremely excellent.

According to the copper foil for a printed wiring board according to the embodiment of the present invention as described above, and the method for producing the same, the material of the nickel-cobalt alloy plating layer 3 is formed of an electroplated film of an alloy of, for example, nickel (Ni) and cobalt (Co), and The concentration of cobalt (Co) is 20% by mass or more and less than 55% by mass, and the total adhesion amount of nickel (Ni) and cobalt (Co) is 20 μg/cm ² or more and less than 40 μg/cm ² , whereby the paste is adhered thereto. After the copper foil for the printed wiring board is placed on the insulating base material, the conductive pattern is patterned, and the optical substrate (optical pattern) is formed by penetrating the insulating substrate, and is defined by Japanese Industrial Standard JIS Z8729. Since the chroma of the color c ^* = (a ^{* 2} + b ^{* 2} ) ^1/2 is 6 or less, it is possible to secure penetration such as penetration even if blackening treatment such as penetration or peeling is extremely unlikely to be performed. The color of the conductor pattern when the insulating substrate is represented by the imine is a practically high visual confirmation property such as when the color difference ΔE ^* ab of the black semiconductor is three or less, and the alignment position is at the time of mounting the semiconductor wafer. It is possible to form a conductor pattern without causing penetration, peeling, or the like in the manufacturing steps of the printed wiring board. .

As described above, in the present invention, it is possible to suppress the use amount of the rare metal nickel (Ni) and cobalt (Co), and it is possible to realize that the etching residue in the pattern processing by the etching method is substantially small, and the circuit visibility is highly high. Copper foil for printed wiring boards.

[Examples]

A copper foil for a printed wiring board as described in the above embodiment is produced as a sample of a copper foil for a printed wiring board according to an embodiment of the present invention. Then, samples of the printed wiring board according to the examples of the present invention were produced using the samples of the copper foil for printed wiring boards (Examples 1 to 6).

In addition, a copper foil for a printed wiring board having a structure which is not necessarily the same as the copper foil for a printed wiring board described in the above-described embodiment is used for comparison and comparison, and a sample of a printed wiring board according to a comparative example is produced. Examples 1 to 6).

Then, the circuit (conductor pattern) in each of the samples was visually confirmed, adhered, and infiltrated, and confirmed and evaluated.

The settings for summarizing these samples and their results are shown in Table 1 below.

<Example 1>

A rolled copper foil having a thickness of 16.3 μm was used as the original foil 1, and was set to a temperature of 40 ° C, a current density of 5 A/dm ² , and a treatment time of 10 in an aqueous solution of 40 g/L of sodium hydroxide and 20 g/L of sodium carbonate. Under the process conditions of two seconds, electrolytic degreasing treatment is performed by a cathodic electrolysis process.

Subsequently, the mixture was immersed in a 50 g/L aqueous sulfuric acid solution at a temperature of 25 ° C for 10 seconds to carry out a pickling treatment.

After the roughening plating treatment is performed on the original foil 1 to form the roughened plating layer 2, a nickel-cobalt alloy plating layer 3, a zinc plating layer 4, and a chromate treatment layer are formed thereon according to the manufacturing method described in the above embodiment. 5. The decane coupling treatment layer 6.

More specifically, the nickel-cobalt alloy plating layer 3 is formed of a sulfuric acid bath, and the zinc plating layer 4 is formed by a chemical solution and then formed by a sulfuric acid bath, and the chromate-treated layer 5 is formed using a commercially available trivalent chromate treatment liquid. The decane coupling treatment layer 6 was formed using 3-aminopropyltrimethoxysilane (KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd.) as a treatment liquid.

The measurement of the adhesion amount and composition of each layer of the metal film was carried out by acid-dissolving the metal film of each layer, and then using an inductively coupled plasma luminescence spectroscopic analyzer (ICP-AES). In other words, first, each sample is cut out at a size of 40 mm × 100 mm, and the adhesive tape is surely adhered to the entire surface of the measurement surface (that is, the back surface of the measurement surface). This is for the purpose of performing acid dissolution as will be described later. The surface was dissolved. The sample was cut into an appropriate size, placed in an ICP-AES measuring beaker, and used as an acid-dissolving treatment liquid to accurately measure an aqueous solution of nitric acid obtained by mixing 10 parts of distilled water in a volume ratio of 1 part of nitric acid (also referred to as (1). +10) Nitric acid) 30 mL, and poured into a beaker in which the sample was placed, and subjected to acid dissolution treatment.

Then, after confirming that the generation of bubbles by the acid dissolution of the metal film was completed, the sample was taken out, and the metal concentration in the solution was measured by ICP-AES. For the measurement method, not only the sample related to Example 1, but also the method described above is uniformly applied to all samples including the samples related to the comparative examples.

On the rough surface of each sample of the copper foil for printed wiring boards which was formed and measured as described above and measured for the adhesion amount and composition of each of the metal films, a polyimide coating was applied at a thickness of 9 mils by a bar coater. The varnish (U-Varnish A manufactured by Ube Industries, Ltd.) was cured by drying in a nitrogen (N ₂ ) atmosphere to serve as an insulating substrate. In Example 1, the drying temperature was set to 200 °C. The thickness of the insulating base material obtained after drying was 25 μm.

The visibility of the circuit was evaluated by measuring the color of the insulating substrate formed by the polyimine resin formed in the above manner using a color difference meter (CR-400 manufactured by KONICA MINOLTA). As a result of the measurement, a conductor pattern formed by patterning the copper foil according to the present embodiment in the above-described manner is detected based on the measurement results of a copper foil containing a black roughened surface which is commercially visible and confirmed. The color of the color (c ^* = (a ^{* 2} + b ^{* 2} ) ^1/2 of the insulating substrate formed by the permeable fluorinated imine resin (conductor pattern) is 6 or less and the color difference ΔE ^* is substantially black ^. When ab is less than 3, it is judged that "the circuit visual visibility is good". The method of judging the visibility of the circuit is also applicable to all samples.

The adhesion strength to the insulating base material was measured according to Japanese Industrial Standard JIS C6481 under the measurement conditions of a circuit width of 1 mm, a peeling angle of 90°, and a peeling speed of 50 mm/sec, and a peeling test was performed to measure the peel strength (N/mm). Used as a parameter for evaluation.

The presence or absence of penetration occurred, and the copper foil for printed wiring boards was subjected to pattern processing by wet etching to form a linear circuit having a width of 1 mm, and further immersed in 3% sulfuric acid at 50 ° C for 1 hour. Using a metal microscope, it was confirmed by penetrating through an insulating substrate formed of a polyimide resin.

In the first embodiment, the total adhesion amount of nickel (Ni) and cobalt (Co) of the nickel-cobalt alloy plating layer 3 (hereinafter, simply referred to as "the adhesion amount of the nickel-cobalt alloy plating layer 3") is 21 μg/cm ^{2 .} . Further, the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 was set to 35 mass%. Further, the drying temperature after the decane coupling treatment was set to 200 °C.

As a result, it was confirmed that the samples related to Example 1 were excellent in terms of all characteristics such as circuit visibility, adhesion strength, and infiltration.

<Example 2>

In the sample of the second embodiment, the adhesion amount of the nickel-cobalt alloy plating layer 3 was set to 39 μg/cm ² , and the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 was 40% by mass. Then, the other settings are set to be the same as those of the sample related to the first embodiment.

The samples relating to the second embodiment were confirmed to be good from the viewpoints of visual confirmation, adhesion strength, and infiltration. In particular, the adhesion strength was slightly increased as compared with 1.2 N/mm in the case of Example 1, and was 1.3 N/mm.

<Example 3>

In the sample of the third embodiment, the adhesion amount of the nickel-cobalt alloy plating layer 3 was 34 μg/cm ² , and the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 was 20% by mass. Then, the other settings are set to be the same as those of the sample related to the first embodiment.

The sample according to the third embodiment was confirmed to be as good as the case of the second embodiment in terms of all the characteristics such as visual confirmation, adhesion strength, and infiltration.

<Example 4>

In the sample of the fourth embodiment, the adhesion amount of the nickel-cobalt alloy plating layer 3 was 34 μg/cm ² , and the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 was 53 mass%. Then, the other settings are set to be the same as those of the sample related to the first embodiment.

The samples related to Example 4 were confirmed to be good from the viewpoints of visual confirmation, adhesion strength, and penetration. In particular, the adhesive strength was higher than 1.2 N/mm and 1.3 mm in the cases of Example 1 and Example 2, and was 1.5 N/mm.

<Example 5>

In the sample of the fifth embodiment, the adhesion amount of the nickel-cobalt alloy plating layer 3 was 34 μg/cm ² , and the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 was set to 35 mass%. Then, the drying temperature after the decane coupling treatment was set to be slightly lower (the lower limit of the suitable numerical range described in the embodiment) at 150 °C. The other settings are set to be the same as the samples related to the first embodiment.

The samples related to Example 5 were confirmed to be good from the viewpoints of visual confirmation, adhesion strength, and infiltration. However, the adhesion strength was slightly lower than that of 1.2 N/mm in the case of Example 1, and was 1.1 N/mm.

<Example 6>

In the sample according to Example 6, the drying temperature after the decane coupling treatment was set to be slightly higher (the upper limit of the appropriate numerical range described in the embodiment) at 300 °C. Then, the other settings are set to be the same as those of the sample related to the fifth embodiment.

As a result, it was confirmed that the samples related to Example 6 were excellent in terms of all of the characteristics such as visual confirmation, adhesion strength, and penetration. In particular, the adhesion strength was 1.5 N/mm as in the case of Example 4, which was 1.5 N/mm, which was the highest level of strength in all samples.

When the results of Example 6 are examined together with the results of Example 5, it is understood that the drying temperature after the decane coupling treatment is set to a slightly higher value within the appropriate numerical range described in the embodiment of the present invention, and it is displayed. Can get a higher adhesion strength.

<Comparative Example 1>

In the sample of the first comparative example, the adhesion amount of the nickel-cobalt alloy plating layer 3 is deliberately set to a lower value of 15 μg/cm which is lower than the lower limit value of the appropriate numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention. ² . The concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 is set to a slightly higher value of 50% by mass in a suitable numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention. Then, the other settings are set to be the same as those of the sample related to the first embodiment.

As a result, in the sample related to Comparative Example 1, the amount of adhesion of the nickel-cobalt alloy plating layer 3 was small, and the visibility of the circuit was remarkably lowered, but it was good from the viewpoint of adhesion strength and penetration. From the results confirmed that, if the applied amount of nickel-cobalt alloy plating layer 3 is the lower limit value 20μg / cm as 15μg / cm ² of the present invention is generally less than a predetermined embodiment ^2, it is difficult or impossible to obtain a good visual confirmation circuit Sex.

<Comparative Example 2>

In the sample of the second comparative example, the adhesion amount of the nickel-cobalt alloy plating layer 3 was deliberately set to a higher value of 50 μg/cm from the upper limit value of the appropriate numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention. ² . In addition, the cobalt (Co) concentration of the nickel-cobalt alloy plating layer 3 is also higher than the upper limit of the appropriate numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention, which is 55 mass%. Then, the other settings are set to be the same as those of the sample of the first embodiment.

As a result, in the sample of Comparative Example 2, although the circuit visibility was good, the adhesion of the nickel-cobalt alloy plating layer 3 was excessive, and significant etching residue occurred, so that the evaluation of the adhesion strength and the infiltration itself was changed. It is impossible.

As a result, it was confirmed that the adhesion amount of the nickel-cobalt alloy plating layer 3 is as high as 55% by mass or more, and good circuit visibility can be obtained. However, as a copper foil for a printed wiring board in which significant etching remains, the pole is extremely There may be fatal flaws.

<Comparative Example 3>

In the sample of the comparative example 3, the adhesion amount of the nickel-cobalt alloy plating layer 3 is within the appropriate numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention, as in the case of the third to sixth embodiments. The value was 34 μg/cm ² .

However, the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 is an extremely low value (1/2 or less) of the lower limit value of the appropriate numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention. ) 10% by mass. Then, the other settings are set to be the same as those of the sample related to the first embodiment.

As a result, in the sample of the comparative example 3, although the visibility of the circuit was confirmed and the penetration was good, the cobalt (Co) concentration of the nickel-cobalt alloy plating layer 3 was extremely low, so the adhesion strength was obtained. It becomes 0.7 N/mm, which is remarkably inferior in terms of adhesion.

From the results, it was confirmed that if the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 is too low, it is difficult or impossible to obtain sufficient adhesion strength.

<Comparative Example 4>

In the sample of the comparative example 4, the adhesion amount of the nickel-cobalt alloy plating layer 3 is 37 μg/cm ^{2 in a} suitable numerical range of the copper foil for a printed wiring board according to the embodiment of the present invention.

However, the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 is set to be 70% by mass higher than the upper limit value of the appropriate numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention. Then, the other settings are set to be the same as those of the sample related to the first embodiment.

As a result, in the samples related to Comparative Example 4, the adhesion strength and the circuit visibility were good. In particular, the adhesion strength is 1.7 N/mm, which is the highest value of all samples. However, infiltration occurs due to an excessively high concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3.

From this result, it was confirmed that if the concentration of cobalt (Co) in the nickel-cobalt alloy plating layer 3 is too high, penetration is highly likely to occur.

<Comparative Example 5>

In the sample of the comparative example 5, the adhesion amount of the nickel-cobalt alloy plating layer 3 is 35 μg/cm ^{2 in a} suitable numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention, and the nickel-cobalt is used. The cobalt (Co) concentration in the alloy plating layer 3 is set to be 35 mass% in a suitable numerical range of the copper foil for printed wiring boards according to the embodiment of the present invention.

However, the drying temperature after the decane coupling treatment is set to be 120 ° C lower than the lower limit of the appropriate numerical range described in the embodiment of the present invention.

As a result, the sample according to Comparative Example 5 was excellent in terms of visual confirmation and penetration of the circuit, but the adhesive strength was 0.8 N/mm, which was remarkably inferior in terms of adhesion.

From the results, it was confirmed that the adhesion strength was remarkably lowered if the drying temperature after the decane coupling treatment was lower than the lower limit value of 150 ° C of the appropriate numerical range as in the case of the comparative example 5 at 120 °C.

<Comparative Example 6>

In the sample of Comparative Example 6, the drying temperature after the decane coupling treatment was set to be 350 ° C higher than the upper limit value of the numerical range suitable for the embodiment of the present invention. Then, the other settings are set to the same settings as those of the sample of the sixth embodiment.

As a result, in the samples related to Comparative Example 6, the circuit visibility was good, but the adhesion strength was 0.5 N/mm, and the adhesion was the lowest in all the samples. This is considered to be because the drying temperature is extremely high at 350 ° C, and therefore the surface of the copper foil for the printed wiring board of the sample of Comparative Example 6 is oxidized and peeled off a plurality of times.

In addition, due to such a significant decrease in the adhesive strength, infiltration also occurs.

From the results, it was confirmed that if the drying temperature after the decane coupling treatment is higher than the upper limit value of 300 ° C of the appropriate numerical range in the case of 350 ° C in the case of Comparative Example 6, the adhesion strength is remarkably lowered, and at the same time, penetration is liable to occur. .

From the experimental results of the various samples related to Examples 1 to 6 and Comparative Examples 1 to 6 as described above, it was confirmed that, according to the present invention, it is formed by plating a film having an alloy of nickel (Ni) and cobalt (Co). The concentration of cobalt (Co) is 20% by mass or more and less than 55% by mass, and the total adhesion amount of nickel (Ni) and cobalt (Co) is 20 μg/cm ² or more and less than 40 μg/cm ² of the nickel-cobalt alloy plating layer 3 The chroma of the color of the conductor pattern formed by patterning the copper foil through the insulating substrate formed of the polyimide resin c ^* = (a ^{* 2} + b ^{* 2} ) ^{1 / Since the amount of 2} is 6 or less, the surface of the copper foil for a printed wiring board having the nickel-cobalt alloy plating layer 3 can be penetrated to suppress the use amount of the rare metal nickel (Ni) and cobalt (Co). When the insulating base material represented by the imine is viewed from the insulating substrate, the color difference from black is ΔE ^* ab is as high as 3, and the circuit can be formed without infiltration, peeling, or the like in the manufacturing process of the printed wiring board. Conductor pattern).

Further, in the above-described embodiments and examples (including comparative examples), the roughened plating layer 2, the nickel-cobalt alloy plating layer 3, the Zn (zinc) plating layer 4, and the chromate-treated layer 5 are provided only on one side of the original foil 1. Although the case of the decane coupling treatment layer 6 has been described, in particular, in order to impart a more strong rust preventing effect to both surfaces of the original foil 1, it is preferable to provide a nickel-cobalt alloy plating layer 3 and Zn on both surfaces of the original foil 1. (Zinc) plating layer 4, chromate treatment layer 5.

In addition, in the above-described embodiments and examples, the copper foil for a printed wiring board according to the present invention has been mainly bonded to an insulating base material made of a polyimide resin, but The material of the insulating base material is of course not limited to the polyimide resin. As the other substance, any substance having a color similar to that of the polyimide resin can be used as an insulating substrate.

Specifically, for example, PET (polyethylene terephthalate), PI (polyimide), PEI (polyether quinone), PEN (polyethylene naphthalate) can also be applied. Ester, polyethylene naphthalate, PP (polypropylene), PE (polyethylene), epoxy (epoxy), nylon (nylon), fluorine resin, and the like.

In addition, the material (composition) of the nickel-cobalt alloy plating layer 3 of the copper foil for a printed wiring board described in the above embodiments and examples is a conductive pattern formed by patterning the copper foil. The coloring of the color of the insulating base material formed of the imide resin c ^* = (a ^{* 2} + b ^{* 2} ) ^1/2 is 6 or less, which is an excellent typical example, and therefore is not limited to The material (composition) specified above. In addition, the material of the nickel-cobalt alloy plating layer 3 may be appropriately changed depending on, for example, the alloy composition and surface roughness of the original foil 1, or the color and light transmittance of the insulating base material. The color pattern c ^* = (a ^*2 + b ^{* 2} ) ^1/2 of the color of the conductor pattern formed by patterning the copper foil to be infiltrated into the insulating base material is 6 or less.

1. . . Original foil

2. . . Rough coating

3. . . Nickel-cobalt alloy coating

4. . . Zinc coating

5. . . Chromate treatment layer

6. . . Decane coupling treatment layer

FIG. 1 is a view schematically showing a main configuration of a copper foil for a printed wiring board according to an embodiment of the present invention.

1. . . Original foil

2. . . Rough coating

3. . . Nickel-cobalt alloy coating

4. . . Zinc coating

5. . . Chromate treatment layer

6. . . Decane coupling treatment layer

Claims (6)

A copper foil for a printed wiring board, which is a copper foil for a printed wiring board which is set to be adhered to a surface of an insulating substrate to form a conductor pattern on a printed wiring board, and has a feature that The nickel-cobalt alloy plating layer having a chroma c ^* =(a ^*2 +b ^*2 ) ^1/2 of 6 or less on the surface of the copper foil for the printed wiring board based on Japanese Industrial Standard JIS Z8729, which is optically detected by an insulating substrate. In addition, the color of the surface of the copper foil for the printed wiring board based on Japanese Industrial Standard JIS Z8730, which is optically detected through the insulating base material, and the nickel-cobalt alloy plating having a color difference ΔE ^* ab of 3 or less . The copper foil for a printed wiring board according to the first aspect of the invention, wherein the insulating base material is made of a polyimide resin. A copper foil for a printed wiring board is a copper foil for a printed wiring board which is provided on a surface of a printed wiring board for bonding a conductive pattern to a surface of an insulating substrate, and is characterized in that it is made of copper or copper. The base foil formed of the base alloy has a nickel-cobalt alloy plating layer on the surface thereof, and the nickel-cobalt alloy plating layer is composed of an electroplated coating of an alloy of nickel and cobalt, wherein the concentration of cobalt is 20% by mass or more and less than 55% by mass, and nickel The total adhesion amount to cobalt is 20 μg/cm ² or more and less than 40 μg/cm ² . The copper foil for a printed wiring board according to claim 3, further comprising a zinc plating layer made of a plating film of zinc on the nickel-cobalt alloy plating layer. The copper foil for a printed wiring board according to the invention of claim 3, wherein the nickel-cobalt alloy plating layer or the zinc plating layer further has a trivalent chromate-treated layer. A method for producing a copper foil for a printed wiring board is a method for producing a copper foil for a printed wiring board which is provided on a surface of a printed wiring board for bonding a conductive pattern to a surface of an insulating substrate. And comprising: a step of forming a nickel-cobalt alloy plating layer on a surface of a raw foil formed of a copper or a copper-based alloy, the nickel-cobalt alloy plating layer being composed of an electroplated coating of an alloy of nickel and cobalt, wherein a concentration of cobalt is 20% by mass The above and less than 55% by mass, and the total adhesion amount of nickel and cobalt is 20 μg/cm ² or more and less than 40 μg/cm ² ; and a step of forming a zinc plating layer composed of an electroplated zinc film on the nickel-cobalt alloy plating layer; a step of forming a trivalent chromate treatment layer on the zinc plating layer; and after forming the trivalent chromate treatment layer, coating an aqueous solution of a decane coupling agent on the surface of the trivalent chromate treatment layer, The step of forming a decane coupling treatment layer by heating and drying at a dry atmosphere temperature of 150 ° C or more and 300 ° C or less.