JPH11340595A - Copper foil for printed circuit boards and copper foil with resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper foil for a printed circuit board and a copper foil with resin, which have high bonding strength to a base material and can form high-density ultrafine wiring. SOLUTION: An electrolytic copper foil 1 having a roughened surface 1a having a surface roughness (Rz) of 2.0 to 4.0 μm, and a thickness 0.01 to 1 mm formed on the roughened surface 1a of the electrolytic copper foil. A nickel layer ² of 0.05 mg / dm ² and a thickness of 0.05 mm formed on the nickel layer 2.
Copper foil for printed circuit boards, comprising a zinc layer 3 of 15-0.5 mg / dm ² .

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 a printed circuit board and a copper foil with a resin, and more particularly to a copper foil having a large etching factor (Ef), enabling high-density ultrafine wiring, and multi-layer printing. The present invention relates to a copper foil for a printed circuit board and a copper foil with resin suitable for use in the manufacture of a circuit board.

[0002]

2. Description of the Related Art A printed circuit board is usually manufactured as follows.

That is, a copper foil for forming a surface circuit is laminated on a surface of an electrically insulating substrate made of glass epoxy resin or glass polyimide resin via a thermosetting adhesive to form a copper-clad laminate. After drilling through holes and plating through holes in the copper-clad laminate in that order, etching the copper foil on the surface to form the desired circuit pattern, and finally, forming the solder resist And other finishing processes are performed.

As an adhesive used in the production of a copper-clad laminate in the above-described process, a glass cloth or the like is usually impregnated with a varnish of the same kind of an electrically insulating resin as the thermosetting resin constituting the base material. A prepreg material that is fitted and made into a semi-cured state and that uses the varnish as a matrix resin is mainly used.

That is, a desired number of prepreg materials are arranged on the upper and lower surfaces of the above-mentioned base material, and a copper foil for forming a surface circuit is laminated on the surface of the prepreg material. Laminates are being manufactured.

Here, as the copper foil for forming the surface circuit,
Generally, an electrolytic copper foil is used. This electrolytic copper foil is manufactured by depositing copper on the surface of a rotating drum having a smooth surface, usually by electrolytic deposition of copper using a copper sulfate bath, and continuously peeling the film from the rotating drum. Therefore, the peeled surface of the obtained electrolytic copper foil is relatively smooth, and the copper deposition surface (mat surface) is relatively rough, and this is the roughened surface during the production of the copper-clad laminate. By joining the matte surface to the prepreg material, the roughened surface exerts an anchoring effect on the prepreg material, and the bonding strength between the prepreg material and the electrolytic copper foil is increased to ensure the reliability as a circuit board. It has been done.

Recently, a resin-coated copper foil in which a roughened surface of a copper foil is coated in advance with an adhesive resin such as an epoxy resin, and the adhesive resin is formed into an insulating resin layer in a semi-cured state (B stage). Is used as a copper foil for forming a surface circuit, and the insulating resin layer side is thermocompression-bonded to a substrate to produce a printed circuit board, especially a multilayer printed circuit board.

By the way, recent various electronic components are highly integrated, and are small in size and have a built-in high-density printed circuit IC.
And LSI are used. Corresponding to this, a circuit pattern on a printed circuit board is also required to have a high density, and a so-called fine-pattern printed circuit board on which a circuit pattern composed of fine line width wiring is formed is required. It became so. For example, in the case of a printed circuit board used for a semiconductor package, a printed circuit board having a high-density ultrafine wiring having a wiring and a line width of about 50 μm is required.

In order to form this fine circuit pattern, it is important to consider an etching factor (Ef) at the time of etching.

Here, the etching factor (Ef) will be described.

Now, it is assumed that a circuit pattern having a sectional shape as shown in FIG. 3 is formed on the substrate 6 by etching the copper foil. In FIG. 3, H is a copper foil 5
Where T is the top width in the circuit pattern and B is
Indicates the bottom width of the circuit pattern.

In the circuit pattern having such a sectional shape, the etching factor (Ef) is a value calculated based on the following equation: Ef = 2H / (BT).
This indicates that the side wall of the formed circuit pattern is almost vertical. Therefore, when a fine circuit pattern is to be formed, Ef should be as small as possible.
It is necessary to perform etching of the copper foil under conditions that increase the value.

The magnitude of this Ef value is determined under various conditions, but it is clear that, when the etching time is long, the side wall of the circuit pattern formed first is also etched, and the verticality of the side wall is lost. As a result, the Ef value becomes small.

For example, when the thickness of the copper foil is large, the time required for etching to the location of the base material becomes long, so that the cross-sectional shape of the circuit pattern is broken and the Ef value becomes small. Such a problem is not so serious when the line width of the circuit pattern to be formed is large, but becomes a serious problem leading to disconnection in the case of a fine circuit pattern having a small line width. .

For example, in the case of a normal printed circuit board, a copper foil obtained by plating an electrolytic copper foil having a thickness of 18 μm with a copper panel having a thickness of about 25 μm is used. When the circuit pattern described above is formed, the cross-sectional shape of the circuit pattern becomes a shape approximate to a triangle, the circuit width is unstable, and there is a risk of disconnection, and eventually, the yield of the printed circuit board is reduced.

In order to cope with such a problem, when forming a circuit pattern having a line width of about 50 μm, an electro-deposited copper foil having a thickness of about 12 μm or less and a copper panel plating having a thickness of about 15 μm are used.

When such a thin copper foil is used, E
It is possible to improve the f-number. However, in the case of this copper foil as well, the surface on the base material side is a roughened surface in order to secure the bonding strength with the base material, and the projections of the roughened surface bite into the base material. In order to completely remove the projection by etching, it is necessary to continue the etching process for a certain period of time. This is because if the protrusions on the roughened surface are not completely removed, the remaining copper will remain, and if the space between the circuit patterns is narrow, insulation failure will occur.

Therefore, in the process of etching and removing the projections on the roughened surface, the etching of the side walls of the already formed circuit pattern also progresses, and the Ef value eventually decreases.

When a thin copper foil is used, it is true that the above problem can be solved by reducing the surface roughness. However, in this case, the bonding strength between the copper foil and the base material is reduced, so that the reliability is reduced. It is difficult to manufacture printed circuit boards with rich and fine circuit patterns.

On the other hand, in order to increase the bonding strength between the copper foil and the substrate, the roughened surface of the copper foil is plated with zinc or a zinc alloy. This is due to the fact that when a copper foil is thermocompression-bonded to a substrate via an adhesive, for example, the copper component reacts with the adhesive to deteriorate the adhesive ability of the adhesive, or the copper foil surface is oxidized. This is for preventing a decrease in bonding strength with the base material. Furthermore, when the protrusions on the roughened surface of the copper foil are biting into the base material, the copper present on the protrusions is easily etched by the action of zinc present at the interface between the protrusions and the base material. This is because the Ef value can be improved.

In this case, if the thickness of the plating layer is too small, the above-mentioned effects cannot be sufficiently exerted, so that the bonding strength is insufficient. And even if the thickness of the plating layer is increased in order to sufficiently exert the above effects, zinc is eluted into the etchant during the etching process and the clearance between the protrusion and the base material is increased, so that the bonding is rather performed. The strength will decrease. Thus, even if the thickness of the zinc layer is too thin or too thick, it has been difficult to obtain sufficient bonding strength between the copper foil and the substrate.

[0022]

As described above, as a practical problem, manufacturing a printed circuit board on which a fine circuit pattern having a large Ef value and a high bonding strength with a base material is formed is considerably problematic. It was difficult. In particular, it is practically impossible to form a circuit pattern of high-density ultra-fine wiring with a line spacing and a line width of about 50 μm using conventional copper foil. It is strongly desired.

The present invention is a copper foil developed to meet the above-mentioned requirements, and realizes a large Ef value and a high bonding strength even in the case of a fine circuit pattern having a line spacing or a line width of about 50 μm. It is an object of the present invention to provide a copper foil for a printed circuit board and a copper foil with a resin that can be used.

[0024]

In order to achieve the above-mentioned object, according to the present invention, a surface roughness (Rz) of 2.0 to 2.0 is provided.
An electrolytic copper foil having a roughened surface of 4.0 μm, and a thickness of 0.01 to 0.05 mg / dm ² formed on the roughened surface of the electrolytic copper foil.
A copper layer for a printed circuit board, comprising a nickel layer formed on the nickel layer and a zinc layer having a thickness of 0.15 to 0.5 mg / dm ² , in particular, the electrolytic copper foil The surface of the electrodeposited copper foil having a surface roughness (Rz) of 2.0 μm or less has particles having a particle diameter of 0.2 to 2.0 μm.
The present invention provides a copper foil for a printed circuit board, which is a surface of the roughened particle layer occupying at least%.

In the present invention, a semi-cured insulating resin layer having a thickness of 20 to 80 μm is in close contact with and bonded to the surface of the zinc layer of the copper foil for a printed circuit. A copper foil with resin for a circuit board is provided.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 1 shows an example A of a copper foil of the present invention. In this copper foil A, one side of the electrolytic copper foil 1 has a roughened surface 1
a, and a nickel layer 2 is formed on the roughened surface 1a.
And the zinc layer 3 are formed in this order, and the bonding surface 1A with the base material is formed.
Is formed.

The above-mentioned roughened surface 1a is JIS B0601
The value of the 10-point average roughness (Rz) specified in the above is 2.0 to 4.0.
μm. When the Rz value is smaller than 2.0 μm, sufficient bonding strength cannot be obtained when the bonding surface 1A is bonded to the base material, and when the Rz value is larger than 4.0 μm, the bonding surface 1A Of the protrusion into the base material, and a long time is required to completely remove the protrusion at the time of etching, so that the Ef value decreases, and it becomes difficult to form a reliable and fine circuit pattern. Become.

In the present invention, an electrolytic copper foil is used as the copper foil.

The reason is that, in the case of electrolytic copper foil, even if the thickness is as thin as 15 μm or less as compared with rolled copper foil, the variation in thickness is small, and a wide foil can be manufactured at a relatively low cost. Can be formed, and as described later, a roughened surface having the aforementioned Rz value can be formed,
This is because it is easy to form a roughened surface having the above-described Rz value, as described later.

The electrolytic copper foil is usually manufactured at a high current density of ^{20 to} 150 A / dm ^{2 in} order to enhance the production efficiency. In this case, the Rz value of the matte surface is 5 μm.
m or more are easily manufactured. However, the Rz value of the matte surface can be reduced to 1 μm by using, for example, a commercially available bright copper plating bath for decoration, an electrolytic bath to which thiourea, molasses, or the like is added, or by changing the electrolytic conditions such as lowering the current density.
It can also be smoothed down and down. Further, for example, an electrolytic polishing method or a chemical polishing method may be applied to a relatively rough mat surface to smooth the mat surface.

In the case of the electro-deposited copper foil 1 used in the present invention, the Rz value of the matte surface is adjusted to 2.0 to 4.0 μm by appropriately selecting the electrolysis conditions and the like in the above-mentioned manufacturing method, and the roughened The surface 1a can also be used.

However, according to the present invention, the R
Considering that it is necessary to make the z-value relatively small, 2.0 to 4.0 μm, and to keep the Rz value within the above-mentioned relatively narrow range, the above-mentioned electrolysis conditions are used during the production of the electrolytic copper foil. An appropriately selected electrolytic copper foil having a mat surface having an Rz value of not more than 2.0 μm is continuously manufactured with a smooth surface, and the mat surface is subjected to a roughening treatment as described below to obtain an Rz value of 2.0.
Preferably, the height is increased to 0 to 4.0 μm.

For example, in the final step in the production of an electrolytic copper foil, copper particles having a particle diameter of 0.2 to 2.0 μm are further precipitated on the mat surface of the already produced copper foil as projections, thereby obtaining This is a process of forming a roughened particle layer in which copper particles occupy 80% or more.

The particles constituting the roughened particle layer have a diameter of 0.2 μm.
When the diameter is smaller than m, the effect of increasing the bonding strength is insufficient because the depth of the protrusion into the base material is shallow, and when the diameter is larger than 2.0 μm, the bonding strength is certainly higher. On the other hand, on the other hand, the surface roughness of the copper foil becomes large and the Ef value becomes small, which causes difficulty in forming a fine circuit pattern. Also, 0.1 in the roughened particle layer.
Even if the occupation ratio of the particles having a particle size of 2 to 2.0 μm is less than 80%, the above-described inconvenience appears. For this reason, the particle size of the roughened particle layer is 0.2 to 2.0 μm.
It is preferable to control m so that it occupies 80% or more.

At this time, if it is attempted to form the above-mentioned roughened particle layer in a short time, the copper particles grow locally in a dendritic manner on the copper foil surface, and the Rz value of the formed roughened particle layer becomes very large. This makes it difficult to form a fine circuit pattern.

Therefore, the R of the formed roughened particle layer
It is preferable to control conditions such as bath composition, bath temperature, current density, and electrolysis time so as to deposit copper particles thinly and uniformly on the entire surface of the copper foil while lowering the z value.

In order to prevent the copper particles constituting the roughened particle layer from falling off, a thin and dense copper plating (capsule plating) layer may be provided on the surface of the formed roughened particle layer. .

In forming the roughened particle layer, first, copper particles having a relatively large particle diameter are formed thinly and uniformly on the mat surface (primary roughening), and then fine particles having a small particle diameter are formed thereon. It is preferable to deposit (secondary roughening) such copper particles into a roughened particle layer.

At this time, the secondary roughening may be continuously performed after the primary roughening. After the primary roughening, the above-mentioned encapsulation plating layer is formed thereon, and then the second roughening is performed in another step. Subsequent roughening may be performed.

Thus, the Rz value on the matte surface of the electrolytic copper foil of the present invention is adjusted to 2.0 to 4.0 μm. Even after the secondary roughening process, the Rz value needs to be set in the above range.

The thickness of the electrolytic copper foil, which is a material for forming the above-mentioned roughened particle layer, is preferably 8 to 10 μm. When the thickness is more than 10 μm, the Ef value becomes small, and it becomes difficult to form a fine circuit pattern having a line interval and a line width of about 50 μm. If the thickness is less than 8 μm, the circuit breaks due to a pinhole. This is because the copper foil strength is low and handling becomes difficult.

The roughened surface 1a thus formed
A nickel layer 2 and a zinc layer 3 are stacked on the substrate.

The zinc layer 3, which is the uppermost layer, is formed by, for example, thermocompression bonding of a copper foil and a base material with an adhesive, the degradation of the adhesive due to the reaction between the copper and the adhesive, and the oxidation of the copper foil surface. The nickel layer 2 prevents the zinc of the zinc layer 3 from being thermally diffused to the copper foil side, and thereby effectively exerts the above-described function of the zinc layer 3 so that the copper layer 2 It is provided to improve the bonding strength between the substrate and the base material.

Here, since zinc is easily diffused into copper, if the thickness of the zinc layer 3 is too thin, the amount of zinc existing on the surface of the copper foil is extremely reduced as a result of the diffusion. The meaning of forming 3 disappears. When the thickness of the zinc layer 3 is increased, the above-mentioned problem does not occur. However, on the other hand, the amount of zinc eluted at the time of etching also increases, and a clearance is generated between the roughened surface of the copper foil and the base material. A decrease in bonding strength is caused. For this reason, the thickness of the zinc layer 3 needs to be set in the range of 0.15 to 0.5 mg / dm ² .

On the other hand, the thickness of the nickel layer 2 functioning as a zinc diffusion preventing layer has a correlation with the thickness of the zinc layer 3 described above.

For example, when the thickness of the nickel layer 2 is small, the function as a zinc diffusion preventing layer is not sufficiently exhibited. It is necessary to allow a relatively large amount of zinc to exist on the nickel layer 2 in consideration of the diffusion amount of nickel. When thinner than 0.01 mg / dm ² the thickness of the nickel layer 2, functions as a diffusion preventing layer of zinc is hardly expressed, and when the thickness of 0.04~0.05mg / dm ^2, the The thickness of the zinc layer formed thereon is 0.15 to 0.5 mg / dm ^2.
The diffusion of zinc can be effectively prevented even if the thickness is around the lower limit in the range of (1).

However, the thickness of the nickel layer 2 was 0.05 mg /
When the thickness is more than dm ² , the function as a zinc diffusion preventing layer is improved, but on the other hand, the nickel layer 2 inhibits the etching, so that the Ef value becomes small at the time of etching the copper foil, so that the fine circuit pattern can be formed. It cannot be formed. For this reason, for example, the space between lines and the line width should be 50 μm.
m, the thickness of the nickel layer 2 is set to 0.0.
It is necessary to set it in the range of 1 to 0.05 mg / dm ² .

From the above, the thickness of the zinc layer 3 is 0.1
It is set to 5~0.5mg / dm ^2. Preferably 0.15 to
To 0.3mg / dm ^2. Further, the thickness of the nickel layer 2 is set to 0.
It is set in the range of 01 to 0.05 mg / dm ² . Preferably, it is 0.015 to 0.04 mg / dm ² . At this time, when the thickness of the nickel layer 2 and 0.01~0.15mg / dm ² sets the thickness of the zinc layer 3 near 0.5 mg / dm ^2, also the thickness of the nickel layer 2 when thick as 0.04~0.05mg / dm ^2, the thickness of the zinc layer 3 is also set near 0.15 mg / dm ^2, it is possible to obtain an appropriate bonding strength.

The nickel layer and the zinc layer are preferably formed by applying a known electrolytic plating method or electroless plating method. Further, the above-mentioned nickel layer may be formed of pure nickel, or may be formed of phosphorus-containing nickel containing 6% by weight or less of phosphorus.

Further, when a chromate treatment is further performed on the bonding surface 1A of the electrolytic copper foil, an oxidation preventing layer is formed on the electrolytic copper foil. The chromate treatment to be applied may be a known method, for example, a method disclosed in JP-A-60-86894. By adhering about 0.01 to 0.2 mg / dm ² of chromium oxide and its hydrate in terms of chromium amount, the electrolytic copper foil can be provided with an excellent anticorrosive ability.

Further, when the above-mentioned chromate-treated surface is further subjected to a surface treatment using a silane coupling material, a functional group having a strong affinity for an adhesive is provided on the surface of the copper foil. This is preferable because the bonding strength with the copper foil is further improved, and the rust resistance and heat resistance of the copper foil are further improved.

Examples of the silane coupling material to be used include vinyl tris (2-methoxyethoxy) silane, 3
-Crysidoxypropyltrimethoxysilane, N- (2
-Aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and the like. These silane coupling agents are usually made into a 0.001 to 5% aqueous solution, applied to the bonding surface 1A of the copper foil, and then heated and dried as it is. Instead of the silane coupling agent, titanium-based,
The same effect can be obtained by using a coupling agent such as a zircon type.

As described above, the thickness of the electrolytic copper foil, which is the material of the copper foil of the present invention, is as very small as 8 to 10 μm in order to form a fine circuit pattern. for that reason,
There is a problem that wrinkles and folds are apt to be formed during handling due to low strength and low waist. Therefore, it is preferable to perform the handling by attaching a releasable resin film to the surface.

Examples of the releasing resin film include a polyethylene terephthalate film coated with an adhesive. Then, the attachment of the film may be before or after the roughening treatment.

Next, the resin-coated copper foil of the present invention will be described.

As shown in FIG. 2, the resin-coated copper foil B covers the bonding surface 1A of the copper foil A of FIG. 1 with an adhesive resin, and the insulating resin layer 4 in a semi-cured state of the adhesive resin. Are in close contact with each other.

The semi-cured state referred to herein is a so-called B-stage state, in which the surface of the resin layer is not sticky even when touched with a finger, and the resin layers can be stored in an overlapped state, and further subjected to a heat treatment. And a state in which a curing reaction occurs.

In this resin-coated copper foil, an adhesive resin can be applied to the copper foil under optimum conditions, and since the adhesive resin layer having a certain thickness is present as an insulating resin layer, the adhesive resin is interposed. As a result, the bonding strength between the base material and the copper foil increases, and the surface after thermocompression bonding becomes very smooth.
It facilitates formation of a circuit pattern of high-density ultrafine wiring.

Further, in the case of the copper foil with resin, since the copper foil is backed up by the bonding resin (insulating resin layer), for example, even when the copper foil is very thin, the printed circuit board can be manufactured. Occasionally, wrinkles and folds of the copper foil hardly occur. That is, this resin-coated copper foil is also a material that is easy to handle.

Further, when this resin-coated copper foil is used, the number of prepreg materials used in the production of a copper-clad laminate can be reduced. In addition, a copper-clad laminate can be manufactured even if the thickness of the adhesive resin layer is set so as to ensure interlayer insulation or no prepreg material is used. At this time, the surface of the base material may be undercoated with an insulating resin to further improve the smoothness of the surface.

When the prepreg material is not used as described above, the material cost of the prepreg material is saved, and the lamination process is simplified, so that it is economically advantageous. The thickness of the multilayer printed circuit board is reduced, and the thickness of one layer is 100 μm.
The advantage is that an ultra-thin multilayer printed circuit board having a thickness of not more than m can be manufactured.

The thickness of the insulating resin layer 4 is 20 to 80 μm
It is preferred that

When the thickness of the insulating resin layer 4 is thinner than 20 μm, the adhesive strength is reduced, and when the copper foil with resin is laminated on a substrate having an inner layer material without interposing a prepreg material, This is because it becomes difficult to ensure interlayer insulation between the circuit and the circuit.

If the thickness of the insulating resin layer is larger than 80 μm, it becomes difficult to form an insulating resin layer having a desired thickness in a single coating step, so that extra material costs and man-hours are required, which is economically disadvantageous. Become. Furthermore, since the formed insulating resin layer is inferior in flexibility, cracks and the like are likely to occur during handling, and excessive resin flow occurs during thermocompression bonding with the inner layer material, making smooth lamination difficult. Because.

[0065]

EXAMPLE 1 (1) Production of Electrodeposited Copper Foil Under the following conditions, length 300mm, width 300mm, thickness 10μ
m of electrolytic copper foil was manufactured.

Bath composition: 55 g / L of metallic copper, 55 g / L of sulfuric acid, 30 ppm of chloride ion (as NaCl), 1.5 ppm of sodium 3-mercapto 1-propanesulfonate, 10 ppm of hydroxyethylcellulose.

Bath temperature: 58 ° C.

Counter electrode: Phosphorus-containing copper plate.

Current density: 50 A / dm ² .

The surface roughness of the matte surface of the obtained electrolytic copper foil was measured by the method specified in JIS B0601. 1
The zero point average surface roughness (Rz) was 1.2 μm. (2) Roughening treatment First, an electrodeposition bath having a composition of metallic copper: 20 g / L and sulfuric acid: 100 g / L was constructed. This is called bath (1). Further, an electrodeposition bath composed of metallic copper: 60 g / L and sulfuric acid: 100 g / L was constructed. This is called bath (2). The matte surface of the electrolytic copper foil was subjected to a roughening treatment (formation of a roughened particle layer) for 5 seconds in a bath (1) under the conditions of a bath temperature of 25 ° C. and a current density of 30 A / dm ^2. Copper particles were deposited on the mat surface. Then bath
Using (2), a plating treatment was performed for 10 seconds at a bath temperature of 60 ° C. and a current density of 15 A / dm ² to form a dense copper encapsulation plating layer covering the copper particles.

At this point, when the surface was observed with a microscope,
The entire surface had a roughened surface on which fine protrusions were formed. The maximum value of the particle diameter of the projections was 1.9 μm, the minimum value was 0.7 μm, and the Rz value was 3.4 μm.

(3) Formation of nickel layer and zinc plating layer A nickel plating bath having the following composition was prepared.

Nickel sulfate hexahydrate 240 g / L, nickel chloride hexahydrate 45 g / L, boric acid 30 g / L, sodium hypophosphite 5 g / L.

A galvanizing bath having the following composition was prepared.

Zinc sulfate heptahydrate 24 g / L, sodium hydroxide 85 g / L.

On the roughened surface of the electrolytic copper foil, the bath temperature of the nickel plating bath was set at 50 ° C., and a stainless steel plate was used as a counter electrode.
Nickel plating at a current density of 0.5 A / dm ² for 1 second to form a phosphorus-containing nickel plating layer having a thickness of about 0.02 mg / dm ^{2 on} the roughened surface. The temperature was 25 ° C., zinc plating was performed for 2 seconds at a current density of 0.4 A / dm ² using a stainless steel plate as a counter electrode, and the thickness was about 0.4 mm.
A zinc plating layer of 20 mg / dm ² was formed.

(4) Surface treatment Then, the copper foil was washed with water, and then chromium trioxide was added at 3 g / L, p
H11.5 aqueous sodium hydroxide solution (liquid temperature: 55 ° C)
For 6 seconds to perform chromate treatment, washed with water and dried.

Further, the copper foil was immersed in an aqueous solution of 2 g / L of vinyl tris (2-methoxyethoxy) silane for 10 seconds and then taken out. Then, the surface of the copper foil was drained by squeezing the surface of the copper foil with a soft rubber plate. It dried at ℃ and performed the silane coupling agent treatment.

(5) Production of single-sided copper-clad laminate The above-mentioned copper foil was placed on a glass fiber epoxy prepreg sheet (FR-4) having a thickness of 1 mm, and the whole was sandwiched between two smooth stainless steel plates. 170 ℃, pressure 50kg
Thermocompression bonding was carried out at 60 cm / cm ² for 60 minutes to produce a single-sided copper-clad laminate having a thickness of 1 mm.

(6) Measurement of bonding strength and etching characteristics The etching characteristics of the copper foil, the bonding strength between the copper foil and the prepreg material, and the hydrochloric acid resistance were measured according to the following specifications.

Etching characteristics: Copper plating of a thickness of 15 μm was performed on the copper foil surface of the single-sided copper-clad laminate, and then 100 m long
A sample having a width of 100 mm was cut out. After a resist film having a thickness of 2.5 μm was formed on the copper plating layer of the sample, a linear parallel pattern having a line width of 35 μm and a line interval of 25 μm was drawn and developed. Then, ferric chloride 2.0 mol / L, hydrochloric acid 0.4 mol / L
Was sprayed to form a circuit pattern.

As for the etching time for the laminated board, a preliminary test was carried out using the same laminated board, and the optimum time until no residual copper was observed at the base of the circuit pattern was examined.

The resulting circuit pattern was observed under a microscope for the presence of shorts and cuts. Those which did not exist were evaluated as good. Bonding strength: A sample was cut out from a single-sided copper-clad laminate, and the sample was peeled off and the peeling strength was measured in accordance with the method specified in JIS C6511. This value is 0.8kg /
Those having a size of not less than cm are judged to be good products.

Hydrochloric acid resistance: A test pattern drawing sample having a line width of 1 mm was immersed in hydrochloric acid (concentration: 25 ° C.) having a concentration of 12% for 30 minutes, taken out, and the above-mentioned peeling strength was measured.
The rate of decrease (%) in peel strength before and after immersion in hydrochloric acid was calculated. The smaller the value, the better the hydrochloric acid resistance.

The measurement results were as follows.

Etching characteristics: Neither short portions nor cut portions (good).

Peel strength: 0.92 kg / cm.

Hydrochloric acid resistance: 1.0%.

Example 2 For the same electrolytic copper foil as in Example 1, the treatment time of the bath (1) was set to 3.
The primary roughening was performed for 5 seconds and the treatment time of the bath (2) was set to 8 seconds. The maximum value of the particle size of the formed copper particles is 1.7 μm,
The minimum value was 0.5 μm, and the surface Rz value was 3.1 μm.

Next, an electrodeposition bath composed of 65 g / L of metallic copper and 110 g / L of sulfuric acid was established. This is called bath (3).

A bath (3) was applied to the first roughened surface at a bath temperature of 55 ° C. and a current density of 3.5 A / dm ^2.
A second roughening treatment was performed for 2 seconds to form a roughened particle layer. The maximum value of the particle diameter of the projections on the roughened surface obtained was 0.9 μm, the minimum value was 0.2 μm, and the Rz value was 3.0 μm.
It was 8 μm.

After forming a phosphorous nickel plating layer and a zinc plating layer in this order on the roughened surface of the copper foil under the same conditions as in Example 1, a chromate treatment and a silane coupling agent treatment were performed.

Using the obtained copper foil, a single-sided copper-clad laminate was produced in the same manner as in Example 1, and its characteristics were evaluated. The results are as follows. Etching characteristics: No short section or cut section (good).

Peel strength: 0.95 kg / cm.

Hydrochloric acid resistance: 1.1%.

In the case of the copper foil of Example 2, the peel strength with the prepreg material is larger than that of the copper foil of Example 1. This is an effect of performing a secondary roughening treatment on the surface of the electrolytic copper foil.

Examples 3 to 6 and Comparative Examples 1 to 4 The thicknesses of the phosphorus-containing nickel plating layer and the zinc plating layer were changed as shown in Table 1 by changing the respective treatment times during nickel plating and zinc plating. A copper foil was manufactured in the same manner as in Example 1 except for the above.

Then, a single-sided copper-clad laminate was manufactured in the same manner as in Example 1 using these copper foils, and their characteristics were evaluated. The results are shown in Table 1.

[0099]

[Table 1] As apparent from comparison of Comparative Example 1 and Comparative Example 2 in Table 1,
Even if the thickness of the zinc plating layer is the same, if the thickness of the phosphorus-containing nickel plating layer is too thin, the peeling strength decreases, and if it is too thick, the etching characteristics deteriorate. Further, as is apparent from comparison between Comparative Examples 3 and 4, even if the thickness of the phosphorus-containing plating layer is the same, if the thickness of the zinc plating layer is too large, deterioration of hydrochloric acid resistance is recognized.

[0100] In contrast, to set the thickness of the phosphorus-containing nickel plating layer within the range of 0.015~0.05mg / dm ^2, and the thickness of the galvanized layer of 0.15~0.5mg / dm ² In the case of Examples 1 to 4 set within the range, the characteristic evaluation is good.

Example 7 Epicron 1121-75M (trade name, bisphenol A type epoxy resin manufactured by Dainippon Ink and Chemicals, Inc.) 1
30 parts by weight, 2.1 parts by weight of dicyancyanamide,
-Ethyl-4-methylimidazole (0.1 part by weight) and methylcellosolve (20 parts by weight) were mixed to prepare a thermosetting adhesive resin varnish.

The above resin varnish was applied to the surface of the copper foil of Example 1 having been subjected to the silane coupling agent treatment to a thickness of 4.0 mg / dm ² by a roll coater.
A heat treatment was performed at 5 ° C. for 5 minutes to form a B-stage insulating resin layer, and the resin-coated copper foil shown in FIG. 2 was produced.

Using this resin-coated copper foil, a single-sided copper-clad laminate was manufactured in the same manner as in Example 1, and the characteristics were evaluated. The results are as follows. Etching characteristics: good.

Peel strength: 0.97 kg / cm.

Hydrochloric acid resistance: 1.0%.

[0106]

As is clear from the above description, the copper foil and the resin-coated copper foil of the present invention have a high bonding strength with the base material despite the relatively small surface Rz value. Further, the Ef value at the time of etching is large, and
It is suitable as a copper foil for a printed circuit board having a high-density ultrafine wiring of about μm.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one example of a copper foil A of the present invention.

FIG. 2 is a cross-sectional view showing one example of a copper foil with resin B of the present invention.

FIG. 3 is a partial cross-sectional view for explaining an etching factor.

[Explanation of symbols]

 Reference Signs List 1 electrolytic copper foil 1a roughened surface of electrolytic copper foil 1 2 nickel layer 3 zinc layer 4 insulating resin layer 5 circuit pattern 6 base material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/38 H05K 3/38 B (72) Inventor Shozo Seino 601-2 Jingzawa, Imaichi, Tochigi Pref. Furukawa Circuit Foil Co., Ltd.

Claims (4)

[Claims] 1. An electrolytic copper foil having a roughened surface having a surface roughness (Rz) of 2.0 to 4.0 μm, and a thickness of 0.01 to 0.01 formed on the roughened surface of the electrolytic copper foil. A nickel layer of 0.05 mg / dm ² and a thickness of 0.15 to 0.1 mm formed on the nickel layer.
A copper foil for a printed circuit board, comprising a zinc layer of 5 mg / dm ² . 2. The roughened surface of the electrolytic copper foil has a surface roughness (R
z) The surface of a roughened particle layer occupying 80% or more of particles having a particle diameter of 0.2 to 2.0 μm formed on the surface of an electrolytic copper foil having a thickness of 2.0 μm or less. Copper foil. 3. A semi-cured insulating resin layer having a thickness of 20 to 80 μm is tightly joined to the surface of the zinc layer of the copper foil for a printed circuit according to claim 1 or 2. Copper foil with resin for printed circuit boards. 4. The copper foil for a printed circuit board according to claim 1, wherein a releasable resin film is adhered to the surface of the electrolytic copper foil opposite to the roughened surface.