JP2006210689A - Copper foil for high frequency printed wiring board and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper foil for a high frequency printed wiring board which can obtain high peel strength to a high frequency substrate represented by a PPE resin impregnated base material, and can raise linearity of a circuit bottom line after circuit pattern formation by etching by realizing ultra low roughness of a roughened surface and reduce transmission loss, and to provide its manufacturing method. <P>SOLUTION: In the copper foil for a high frequency printed wiring board and its manufacturing method, a roughening treatment layer consisting of spherical fine roughening particle of a diameter of 0.05 to 1.0 μm is applied to at least one surface of a copper foil. Furthermore, a heat-resistant/rust proofing layer consisting of at least one or more kinds among molybdenum, nickel, tungsten, phosphorus, cobalt and germanium is applied on the roughening treatment layer; a chromate film is further applied on the heat-resistant/rust proofing layer; and a silane coupling agent layer is further applied on the chromate film layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copper foil for printed wiring boards and a method for producing the same, and more particularly to a copper foil for high-frequency printed wiring boards and a method for producing the same.

Copper foil is used in large quantities especially for printed wiring boards for electronic and electrical materials.
Printed wiring boards have been improved in performance and reliability. Therefore, required characteristics are complicated and diversified. Similarly, strict quality requirements have been imposed on copper foil, which is one of the constituent materials of this printed wiring board.

  In the production of a printed wiring board, first, the rough side of a copper foil is laminated together with an insulating synthetic resin-impregnated base material, and heat-pressed by a press to obtain a copper-clad laminate. In general, a glass epoxy substrate (FR-4) often used is completed by pressing at a temperature of about 170 ° C. for 1 to 2 hours. A special resin-impregnated base material using polyimide resin, halogen-free resin, high heat resistance resin, low dielectric constant resin, or the like may require a high temperature such as 200 ° C. for 2 hours.

  As copper foils for printed wiring boards, electrolytic copper foils having one side rough surface and one side glossy surface are overwhelmingly used. Usually, the electrolytic copper foil is subjected to electrolytic deposition of copper from an electrolytic solution of copper by an electrodeposition apparatus to produce a raw foil called untreated copper foil, and then a series of surface treatments are performed by a processing apparatus.

  In general, the untreated copper foil rough surface side (non-glossy surface side) is pickled, roughened and treated to ensure the peel strength from the resin, and the heat resistance in its peelability The process is completed by improving and stabilizing the chemical resistance and etching characteristics. Various techniques have been developed and proposed for these treatments, resulting in a highly functional surface. In the recent increase in the density of printed wiring boards, for example, in thin printed wiring boards and build-up printed wiring boards, the resin layer that becomes the insulating layer is extremely thin. May cause problems.

  In addition, by making fine lines, it is desired to reduce the roughness on the rough surface side for the reason that the smaller copper foil rough surface can maintain insulation between lines. However, if the peel strength is not enough, delamination problems such as peeling and floating of the copper foil circuit during the manufacturing process and after becoming a product will occur, so the surface treatment that satisfies both is most preferable, An excellent method is required because they are mutually contradictory.

  Furthermore, glass epoxy substrates (FR-4) accounted for the majority of printed wiring boards, but in recent years electronic devices have become smaller, lighter, more functional, less environmentally hazardous substances are used, and Pb-less soldering is required. The use frequency of special resin-impregnated base materials is increasing for reasons such as an increase in mounting temperature accompanying an increase in the use frequency. In particular, in the multi-functionalization of electronic devices, it is necessary to exchange a large amount of information accurately in a short time, and it is necessary to increase the speed of signals, that is, to increase the frequency.

  A printed wiring board used for a substrate that handles high-frequency signals requires a base material with low transmission loss for the purpose of improving signal quality, and copper foils are also required to have similar characteristics. Transmission loss can be broadly classified into three factors: conductor loss, dielectric loss, and width radiation loss. The inner copper foil is caused by the conductor loss. Conductor loss means that when the frequency of an electrical signal enters the GHz band region, current does not flow easily inside the conductor and the skin effect that flows only on the surface of the conductor becomes extremely strong. It is a phenomenon in which resistance decreases and increases. As a method for reducing this phenomenon, it is known that it can be achieved by reducing the roughness of the copper foil on the substrate adhesion surface side to an extremely low roughness.

  That is, when a pattern is formed using a copper foil having a large roughness, the circuit bottom line has poor linearity due to the irregularities of the rough shape of the copper foil, and exhibits a curved irregular shape. For this reason, since the distance that the signal flows is increased due to the skin effect, there arises a problem that the signal quality is deteriorated. On the other hand, in the case of an ultra-low roughness copper foil, the circuit bottom line linearity is extremely high because there is almost no roughness on the rough surface, and as a result, the distance that the signal flows is shorter than the copper foil with a large roughness. This is because problems such as signal delay are less likely to occur.

  In this way, it is possible to reduce the transmission loss by making the copper foil substrate adhesion surface side ultra low roughness, but on the other hand, the mechanical anchoring effect with the substrate becomes low and the peeling strength is remarkably high. Decreasing problems arise. In particular, high-frequency substrates represented by PPE (polyphenylene ether) resin-impregnated substrates have extremely weak adhesion to copper foil, and the ultra-low roughness described above is a characteristic that is contrary to improved adhesion. Therefore, there has been a waiting for a processing method that satisfies both the characteristics of reduction of transmission loss and improvement of peeling strength.

  As described above, various copper foil treatment methods have been developed that satisfy both the properties of strong peel strength and ultra-low roughness rough surface at the same time. In the conventional technique, for example, a method of performing three-stage electrolytic treatment in an acidic electrolytic bath containing arsenic (see Patent Document 1), or in an acidic copper electrolytic bath containing arsenic, antimony, bismuth, selenium, and tellurium is limited. There are methods of electrolysis before and after the current density (see Patent Document 2 and Patent Document 3), and arsenic is often used in practice.

  There is also a method of electrolysis around a limit current density in an acidic copper electrolytic bath containing one or two of chromium or tungsten (Patent Document 4). There is also a method (Patent Document 5) in which 0.001 to 5 g / L of germanium is added to an electrolytic bath for forming a roughened layer to form roughened particles. Further, there is a method (Patent Document 6) in which at least one of molybdenum, iron, cobalt, and nickel is contained in an acidic electrolytic bath to form coarse particles.

  However, in the conventional methods as described above, the use of substances harmful to the human body such as arsenic, selenium, and tellurium has been extremely limited due to environmental problems that have become particularly severe in recent years. From the viewpoint of reuse of printed wiring boards or industrial waste, there is concern about accumulation of harmful components contained in copper foil, and alternative methods are strongly demanded.

In addition, the method containing chromium or tungsten, the method containing germanium, and the method containing at least one of molybdenum and iron, cobalt, and nickel certainly improve the uniformity compared to the additive-free FR-4 group. For materials, etc., strong peeling strength can be obtained due to the mechanical anchoring effect, but the roughness of the rough surface is still large for use in high-frequency printed wiring board applications, resulting in inferior circuit bottom line linearity and increased transmission loss. Is not good.
JP-B 53-38700 Japanese Patent Publication No.53-39327 Japanese Patent Publication No.54-38053 Japanese Patent No. 2717911 Japanese Patent No. 3121850 JP-A-11-256389

  The problem to be solved by the present invention is that it is possible to obtain a strong peeling strength with respect to a high-frequency substrate typified by a PPE resin-impregnated base material by an easy method, and by etching with ultra-low roughness It is an object of the present invention to provide a new copper foil for a high-frequency printed wiring board and a method for manufacturing the same, which can improve the linearity of the circuit bottom line after forming a circuit pattern and can greatly reduce transmission loss.

  As a result of investigating various copper foil treatment methods to satisfy the above-mentioned ultra-low roughness and strong peel strength at the same time as a copper foil for high-frequency printed wiring boards, the diameter is 0.05 to 1.0 μm on at least one surface of the copper foil. A heat treatment / rust prevention comprising at least one of molybdenum, nickel, tungsten, phosphorus, cobalt, and germanium on the roughening layer. Applying a layer, further applying a chromate film layer on the heat and rust preventive layer, and further applying a silane coupling agent layer on the chromate film layer, the ten-point average roughness Rz of the copper foil treated surface is 2.5 μm or less. In addition, when a copper-clad laminate is manufactured by hot pressing with a high-frequency substrate and press using the copper foil with the above surface treatment, the circuit after forming a circuit pattern by etching is strong. Bo Reduction of high transmission loss linearity of Murain is possible to become the high frequency copper foil for printed wiring boards and a manufacturing method thereof.

  The effect of the present invention is that by performing the above surface treatment on at least one surface of the copper foil, it becomes possible to obtain a high-frequency substrate represented by a PPE resin-impregnated substrate and a strong peeling strength, and with an ultra-low roughness As a result, the linearity of the circuit bottom line after circuit pattern formation by etching is improved, and transmission loss can be significantly reduced. The copper foil subjected to the surface treatment of the present invention is very suitable as a copper foil for a high-frequency printed wiring board, particularly for a printed wiring board that has been required to have increasingly severe characteristics in recent years. In addition, since it has the characteristics that fine pattern, ultra-low roughness and appearance color tone can be black, it is also suitable for copper foil for electromagnetic wave shielding in plasma displays.

The present invention is described in detail below.
In the present invention, even if any of the surface treatments described in detail below is lacking, the intended surface-treated copper foil cannot be obtained.
First, although it is the untreated copper foil to be used, there is no need to limit to rolling and electrolytic copper foil, and any copper foil may be used.

(Roughening treatment layer consisting of spherical fine roughening particles having a diameter of 0.05 to 1.0 μm)
The roughening treatment layer is a first surface treatment layer formed on the surface of the untreated copper foil and is formed by an aqueous solution electroplating method. By applying this treatment layer, the wettability with the resin base material is improved, and the peel strength after molding the copper-clad laminate is improved.

  In addition, this treatment is a roughening treatment layer consisting of fine roughening particles, and as mentioned earlier, unlike the general roughening treatment method, it is possible to suppress the increase in roughness of the surface extremely low. Also, there is an advantage that the linearity of the circuit bottom line after the high etching accuracy and the circuit pattern formation by etching can be increased. In addition, there is an advantage that the non-treated copper foil and the roughened layer are highly fixed and so-called powder fall is small.

  When the diameter of the roughened particles of the present invention is in the range of 0.05 to 1.0 μm, all the characteristics are good, but outside this range, when the diameter is less than 0.05 μm, the peel strength from the base resin is obtained. There may be a problem that becomes difficult. On the other hand, when the thickness exceeds 1.0 μm, the roughness of the rough surface increases, and as a result, problems such as poor etching accuracy and easy etching residue may occur.

  The roughened particle diameter of the present invention is strongly influenced by the shape of the untreated copper foil surface to be treated, the roughness of the rough surface, and the electrolytic current density. For example, when the untreated copper foil surface roughness is small and the electrolytic current density is high, the roughened particle diameter tends to be small. Conversely, when the untreated copper foil surface roughness is large and the electrolytic current density is low, roughened particles The diameter tends to increase. For this reason, in order to obtain the target rough particle diameter, it is effective to set the electrolytic current density according to the roughness of the untreated copper foil surface to be treated.

  The appearance color tone of this treatment layer is brown to black, and the color tone of the copper foil can be controlled by a combination of a sulfonate salt of an active organic sulfur compound added to a sulfuric acid / copper sulfate bath and metal ions. For example, in the case of adding a sulfonate of an active organic sulfur compound alone or a combination of a sulfonate of an active organic sulfur compound and at least one of tungsten ion, cobalt ion and nickel ion, a roughened layer Exhibits brown to brown color, and exhibits brown to black color when added in combination with a sulfonate salt of an active organic sulfur compound and at least one of titanium ions and molybdenum ions.

The sulfonate of the active organic sulfur compound is a symmetric or asymmetrical disulfide sulfonate represented by the general formula NaSO ₃ -R ₁ -SSR ₂ -SO ₃ Na, or a general formula HS-R ₁ -SO ₃ Na or The thiol sulfonic acid represented by the general formula HS-Ar-SO ₃ Na is used. In the formula, R ₁ and R ₂ represent an alkylene group having 2 or 3 carbon atoms and may be the same or different. Ar represents an aromatic group. Representative compounds of the sulfonate salt of the active organic sulfur compound suitable for the present invention are those shown in Chemical Formula 1, Chemical Formula 2, Chemical Formula 3, and Chemical Formula 4.

The metal ion supply source is preferably a sulfate but is not particularly limited in order to prevent mixing of impurity ions other than sulfate ions.
Examples of the electrolytic bath and electrolysis conditions for applying the roughening treatment layer include the following conditions, but are not particularly limited thereto.

(Electrolytic solution composition)
(1) Copper sulfate pentahydrate 10-100 g / L (particularly preferably 30-70 g / L)
(2) Sulfuric acid 20 to 200 g / L (particularly preferably 50 to 130 g / L)
(3) Sodium 3-mercapto-1-propanesulfonate 0.005 to 2 g / L (particularly preferably 0.03 to 1 g / L)
(4) Sodium tungstate dihydrate 0.0018-0.18 g / L (particularly preferably 0.009
(~ 0.09g / L)
(5) Disodium molybdate dihydrate 0.05-1 g / L (particularly preferably 0.1-0.5 g
/ L)
(6) Cobalt sulfate heptahydrate 3-100 g / L (particularly preferably 5-70 g / L)
(7) Nickel sulfate hexahydrate 3 to 100 g / L (particularly preferably 5 to 70 g / L)
(8) 24% titanium sulfate solution 0.76 to 15.2 mL / L (particularly preferably 1.52 to 4.56 mL / L)

(Electrolysis conditions)
Current density 3 to 100 A / dm ² (particularly preferably 5 to 50 A / dm ² )
Electricity 40 ~ 200A ・ sec / dm ² (Preferably 60 ~ 150A ・ sec / dm ² )
Liquid temperature 20-70 ° C (particularly preferably 30-50 ° C)
Anode Platinum Copper sulphate pentahydrate is suitably 10-100g / L. Outside this range, if less than 10g / L,
Precipitation efficiency deteriorates, and it becomes difficult to obtain sufficient peeling strength. In addition, in order to obtain a sufficient peel strength, it is necessary to lengthen the electrolytic reaction time, resulting in disadvantages such as being uneconomical. Conversely, when it exceeds 100 g / L, the generation | occurrence | production of roughening particle | grains increases, rough surface roughness raises, and the malfunction of the powder fall of roughening particle | grains will arise.

  Among the above electrolytic bath compositions, (1) to (3) are essential, but (4) to (8) may be added as necessary. For example, the addition of tungsten ions, cobalt ions, and nickel ions makes the coarse particle diameter larger than in the cases of (1) to (3) alone, so that the mechanical anchoring effect is excellent and the peel strength is increased. Further, the addition of titanium ions and molybdenum ions makes it possible to make the color tone black, so that it is suitable when a black copper foil is required for plasma display applications. Of course, the use of a sulfonate salt of an active organic sulfur compound is sufficiently effective, and other combinations are possible.

(Heat-resistant / rust-proof layer composed of at least one of molybdenum, nickel, tungsten, phosphorus, cobalt, germanium)
The heat-resistant / rust-proof layer is a second surface treatment layer formed after the formation of a roughening treatment layer composed of spherical fine roughening particles as a first treatment layer, and is formed by an aqueous electrolytic plating method. By applying this treatment layer, various characteristics are improved. For example, characteristics such as improved heat resistance and rust prevention, and prevention of copper residue after etching can be imparted. Although the detailed mechanism of the copper residue after etching is not known, it is eliminated by treating different types of metal layers other than copper on the roughened layer. It is considered that a compound that is difficult to be etched is generated by this reaction.

  More preferably, the heat- and rust-proof layer is an alloy layer based on nickel or cobalt. The reason for this is that the nickel single layer and the nickel-cobalt layer are soluble in ferric chloride and cupric chloride etchants that are often used in circuit formation, but are often used in pattern plating methods. It has a serious drawback that it is insoluble in the etching solution and causes an etching residue (stain) that impairs electrical insulation. When considering the narrowing of circuits in recent years, it is an indispensable condition that a fine pattern can be drawn with ferric chloride or cupric chloride, but alkali etching is also an indispensable condition due to various types of resists.

  In addition, although the cobalt single layer is not as good as zinc, it has the disadvantage that undercutting occurs after immersion in hydrochloric acid and after immersion in a cyanide bath used in gold plating or the like. On the other hand, when the heat / rust preventive layer is a heat / rust preventive layer made of nickel and / or cobalt containing at least one of molybdenum, tungsten, phosphorus, and germanium, in addition to the above characteristics, the alkali etchant Properties such as being soluble and eliminating undercutting after immersion in the active treatment solution are imparted to provide a highly versatile copper foil.

Precipitation amount of heat and anticorrosive layer is also important range of 50 to 1000 mg / m ² are preferred, more preferably from 100 to 500 mg / m ^2. When the deposition amount of this alloy barrier layer is less than 50 mg / m ² , the effectiveness of this alloy barrier cannot be fully exerted, resulting in poor heat resistance and rust prevention, and copper defects may occur after etching. There is. On the other hand, when it exceeds 1000 mg / m ² , no further improvement in properties is observed, and the purity of copper decreases, resulting in high costs and uneconomical.
The electrolytic bath for applying the heat and rust preventive layer has, for example, the following composition, but is not particularly limited thereto.

(Cobalt-molybdenum layer)
Cobalt sulfate heptahydrate 10-100 g / L (particularly preferably 20-50 g / L)
Disodium molybdate dihydrate 1-80 g / L (particularly preferably 5-50 g / L)
Trisodium citrate dihydrate 5-100 g / L (particularly preferably 20-60 g / L)
pH 4.0 to 10.0 (particularly preferably 5.0 to 7.0)

(In the case of nickel-phosphorus layer-tungsten layer)
Nickel sulfate hexahydrate 10-100g / L (particularly preferably 20-50g / L)
Sodium hypophosphite monohydrate 0.1-10 g / L (particularly preferably 0.5-5 g / L)
Sodium tungstate dihydrate 0.1-20 g / L (particularly preferably 0.5-10 g / L)
Sodium acetate trihydrate 2-20g / L (particularly preferably 3-15g / L)
pH 3.0-5.5 (particularly preferably 3.5-5.0)

(Cobalt-nickel-tungsten layer)
Cobalt sulfate heptahydrate 10-100 g / L (particularly preferably 20-50 g / L)
Nickel sulfate hexahydrate 10-100g / L (particularly preferably 20-50g / L)
Sodium tungstate dihydrate 1-80 g / L (particularly preferably 5-50 g / L)
Trisodium citrate dihydrate 5-100 g / L (particularly preferably 20-60 g / L)
pH 4.0-7.0 (particularly preferably 5.0-7.0)

(Cobalt-nickel-germanium layer)
Cobalt sulfate heptahydrate 10-100 g / L (particularly preferably 20-50 g / L)
Nickel sulfate hexahydrate 10-100g / L (particularly preferably 20-50g / L)
Germanium dioxide 0.1-10 g / L (particularly preferably 0.3-3 g / L)
Trisodium citrate dihydrate 5-100 g / L (particularly preferably 20-60 g / L)
pH 3.0 to 10.0 (particularly preferably 4.0 to 7.0)
Moreover, you may add sodium sulfate as provision of electroconductivity.

The electrolysis conditions for applying the heat and rust preventive layer are, for example, the following conditions, but are not particularly limited thereto.
Current density 0.1 to 10.0 A / dm ² (particularly preferably 0.5 to 5.0 A / dm ² )
Electricity 5.0 ~ 40.0A ・ sec / dm ² (Preferably 10.0 ~ 30.0A ・ sec / dm ² )
Liquid temperature 20-50 ° C (particularly preferably 25-40 ° C)
Anode platinum

(Chromate film layer)
The chromate film layer is a roughened layer consisting of fine spherical rough particles as the first treatment layer, and at least one of molybdenum, nickel, tungsten, phosphorus, cobalt and germanium as the second layer surface treatment. This is the third surface treatment layer after forming the heat-resistant / rust-proof layer, and is formed by aqueous electrolytic plating or immersion in aqueous solution. By applying this chromate film layer, various properties are improved, and for example, the effect of improving the rust prevention property and the peeling strength with the base material is brought about.

Moreover, the bath for forming this chromate film layer may be a known bath, and any material having hexavalent chromium such as chromic acid, sodium dichromate, potassium dichromate, etc. may be used. Incidentally, precipitation form of chromium after chromate film layer formed is in a state in which Cr (OH) ₃ and Cr ₂ 0 ₃ are mixed, is precipitated in the form of trivalent chromium not adversely affect hexavalent chromium on the human body . The chromic acid solution may be alkaline or acidic. Each of the above two types of chromic acid solution has advantages and disadvantages, and may be properly used depending on the purpose of use. However, when an alkaline chromic acid solution is used, the chromate film layer has a slightly lower corrosion resistance than the acidic chromic acid solution. Although there is a disadvantage that the peel strength with the substrate is slightly inferior, the above-mentioned problem does not occur even when a chromate film layer is applied with an alkaline chromic acid solution on the surface treatment of the present invention.

  In addition, an alkaline zinc chromate solution containing zinc ions and hexavalent chromium ions described in Japanese Patent Publication No. 58-15950 may be used as the alkaline chromic acid solution. Rust prevention can be improved compared to the chromate film layer.

Examples of the electrolytic bath and electrolysis conditions for applying the chromate film layer include, but are not limited to, bath compositions and conditions as shown below.
Sodium dichromate 10g / L
Bath temperature 30 ℃
pH 4.2
Current density 0.5A / dm ²
Electrolysis time 5 seconds Anode Platinum

(Silane coupling agent layer)
The silane coupling agent layer is at least one of a roughening treatment layer comprising spherical fine roughening particles as the first treatment layer and molybdenum, nickel, tungsten, phosphorus, cobalt, and germanium as the second surface treatment. It is a 4th layer surface treatment layer that is formed after the heat-resistant / rust-proof layer and the 3rd surface treatment layer are formed, and an appropriate amount is added to water and applied as an aqueous solution by dipping or spraying. . By applying a silane coupling agent layer, not only can the peel strength be improved, but also the deterioration of the peel strength after severe testing can be suppressed, and the rust prevention property has also been improved, providing excellent versatility. It becomes the copper foil for printed wiring boards provided. There are various types of silane coupling agents such as epoxy group, amino group, mercapto group, vinyl group, methacryloxy group, styryl group, etc., but each has different characteristics, and it is compatible with the base material, so it is necessary to select it. is there.

Examples of the bath for applying the silane coupling agent layer include, but are not particularly limited to, the following composition and conditions.
γ-Aminopropyltriethoxysilane 2mL / L
Bath temperature 30 ° C
Immersion time 15 seconds

Examples of the present invention will be described below.
(Examples 1 to 16)

  Untreated copper foil manufactured by Fukuda Metal Foil Powder Industry: SV-10 μm was prepared. The copper foil is glossy on any surface in an untreated state, but the rough surface roughness Rz (ten-point average roughness) of each surface is different, and is generally rough surface, mat surface, non-drum surface, etc. Rz of the plating finish surface called 0.8 μm, and Rz of the plating start surface called glossy surface, shiny surface, drum surface, etc. is 1.4 μm. Hereinafter, the plating end surface of the SV foil is referred to as a rough surface, and the plating start surface is referred to as a smooth surface.

First, the untreated copper foil was immersed in a sulfuric acid solution having a sulfuric acid concentration of 100 g / L and a bath temperature of 30 ° C. for 60 seconds to remove the surface oxide layer, and then washed with water.
Next, the roughening treatment layer composed of spherical fine roughening particles to be the first surface treatment layer of the present invention was treated with respect to Examples 1 to 16 with the following electrolytic bath composition, bath temperature, and electrolysis conditions.
Copper sulfate pentahydrate 50g / L
Sulfuric acid 100g / L
Additives See Table 1 Bath temperature 40 ° C
Current density See Table 1 Electrolysis time See Table 1 Anode See Table 1 for the surface treated with platinum copper foil

  After washing with water, the heat- and rust-preventing layer to be the second surface treatment layer of the present invention uses platinum as the anode for Examples 1 to 16, and the electrolytic bath composition shown in Table 1 with a constant bath temperature of 30 ° C, pH, The treatment was performed under electrolytic conditions.

After washing with water, the chromate film layer serving as the third surface treatment layer of the present invention was treated with the electrolytic bath composition, pH, and electrolysis conditions shown below for Examples 1 to 16.
Sodium dichromate 10g / L
Bath temperature 30 ℃
pH 4.2
Current density 0.5A / dm ²
Electrolysis time 5 seconds Anode Platinum

After washing with water, the silane coupling agent layer, which is the fourth surface treatment of the present invention, was treated with the bath composition, bath temperature, and immersion time shown below for Examples 1 to 16.
γ-Aminopropyltriethoxysilane 2mL / L
Bath temperature 30 ° C
Immersion time 15 seconds After the silane coupling agent layer was formed, it was naturally dried without being washed with water.

Table 2 shows the results of quantifying the amount of each element deposited on the surface of the surface-treated copper foils of Examples 1 to 16 subjected to the surface treatment of the present invention comprising four layers as described above.
Next, this surface-treated copper foil and a PPE resin-impregnated base material manufactured by Company A were hot-pressed under a condition of 200 ° C. for 2 hours by a press to produce a copper-clad laminate.

Comparative example

A comparative example will be described below.
(Comparative Example 1)

A surface treatment was performed in the same manner as in Examples 1 to 16 except that a heat-resistant / rust-proof layer was not applied to the rough surface side of SV-10 μm, and a copper-clad laminate was produced in the same manner. The electrolytic bath composition and electrolysis conditions are shown in Table 1, and the results of quantifying the amount of precipitation of each element treated on the surface are shown in Table 2.
(Comparative Example 2)

Surface treatment was performed in the same manner as in Examples 1 to 16 except that the chromate film layer was not applied to the rough surface side of SV-10 μm, and a copper clad laminate was produced in the same manner. The electrolytic bath composition and electrolysis conditions are shown in Table 1, and the results of quantifying the amount of precipitation of each element treated on the surface are shown in Table 2.
(Comparative Example 3)

Surface treatment was performed in the same manner as in Examples 1 to 16 except that the silane coupling agent layer was not applied to the rough surface side of SV-10 μm, and a copper clad laminate was produced in the same manner. The electrolytic bath composition and electrolysis conditions are shown in Table 1, and the results of quantifying the amount of precipitation of each element treated on the surface are shown in Table 2.
(Comparative Example 4)

Surface treatment was performed in the same manner as in Examples 1 to 16 except that a roughening treatment layer composed of spherical fine roughening particles was not applied to the rough surface side of SV-10 μm, and a copper clad laminate was formed in the same manner. Produced. The electrolytic bath composition and electrolysis conditions are shown in Table 1, and the results of quantifying the amount of precipitation of each element treated on the surface are shown in Table 2.
(Comparative Example 5)

First, SV-10 μm was immersed in a sulfuric acid solution having a sulfuric acid concentration of 100 g / L and a bath temperature of 30 ° C. for 60 seconds to remove the surface oxide layer, and then washed with water. Next, a roughening treatment was performed on the smooth surface side of the copper foil under the following electrolytic bath composition, bath temperature, and electrolytic conditions.
Copper sulfate pentahydrate 100g / L
Sulfuric acid 100g / L
Chromic anhydride 0.1g / L
Sodium tungstate 0.01g / L
Bath temperature 40 ℃
Current density 10A / dm ²
Electrolysis time 20 seconds Anode Platinum

After washing with water, cover plating was performed with the following electrolytic bath composition, bath temperature, and electrolytic conditions.
Copper sulfate pentahydrate 250g / L
Sulfuric acid 100g / L
Bath temperature 45 ℃
Current density 10A / dm ²
Electrolysis time 30 seconds Anode Platinum

After washing with water, a heat-resistant / rust-proof layer was applied with the following electrolytic bath composition, bath temperature, and electrolytic conditions.
Cobalt sulfate heptahydrate 40g / L
Disodium molybdate dihydrate 25g / L
Trisodium citrate dihydrate 40g / L
pH 5.6
Bath temperature 30 ℃
Anode platinum

After washing with water, a chromate film layer was applied with the following electrolytic bath composition, pH, and electrolysis conditions.
Sodium dichromate 10g / L
Bath temperature 30 ℃
pH 4.2
Current density 0.5A / dm ²
Electrolysis time 5 seconds Anode Platinum

After washing with water, a silane coupling agent layer was applied with the following bath composition, bath temperature, and immersion time.
γ-Aminopropyltriethoxysilane 2mL / L
Bath temperature 30 ° C
Immersion time 15 seconds After the silane coupling agent layer was formed, it was naturally dried without being washed with water.

A copper clad laminate was produced from the surface-treated copper foil obtained as described above in the same manner as in Examples 1-16. The electrolytic bath composition and electrolysis conditions are shown in Table 1, and the results of quantifying the amount of precipitation of each element treated on the surface are shown in Table 2.

  Peel strength of copper-clad laminate obtained as described above, copper foil treated surface roughness (Rz: 10-point average roughness), roughened particle diameter, circuit bottom line after circuit pattern formation by etching Table 2 shows the results of evaluating the linearity and the copper residue after etching. In addition, the evaluation method of the linearity of the circuit bottom line after the circuit pattern formation by an etching and the copper residue after an etching is shown below.

(Linearity of circuit bottom line after circuit pattern formation by etching)
After pattern printing of line / space = 50 μm / 50 μm with a liquid resist, a circuit pattern was formed by cupric chloride etching. The circuit pattern was observed from the upper surface with an electron microscope at a magnification of 2000 to determine the linearity of the bottom line.
High linearity with no bottom line curvature ○
The bottom line is curved ×

(Copper residue after etching)
The presence or absence of unmelted copper was visually observed in the copper foil etched portion of the copper clad laminate.
There is no unmelted copper ○
There is unmelted copper ×

  As shown in Table 2, the copper foils having the surface treatment layers of Examples 1 to 16 of the present invention have strong peeling strength from the PPE resin-impregnated base material, which is a high-frequency base material, and the coarse particles are extremely fine ( (Refer to Fig.2-4) Since the increase in roughness of the rough surface can be made extremely low, the linearity of the circuit bottom line after circuit pattern formation by etching is also extremely high (see Fig.6), and there is a concern about copper residue after etching. It can be seen that it has extremely high characteristics as a copper foil for high-frequency printed wiring boards.

  Next, Comparative Examples 1 to 4 in which one type of the present invention treatment was not performed will be described. In Comparative Example 1 in which the heat-resistant / rust-proof layer was not applied, the peel strength was low, and the copper residue after etching was confirmed. In Comparative Example 2 in which the chromate film layer treatment was not performed, the peel strength was low, and the copper residue after etching was confirmed. It can be confirmed that Comparative Example 3 in which the silane coupling agent treatment was not performed has a weak peel strength. It can be confirmed that Comparative Example 4 in which the roughening treatment was not performed also has a low peel strength.

In Comparative Example 5 using tungsten and chromium as a roughening treatment bath additive, the roughening particles are messy and the roughness of the rough surface is high (see Fig. 5). The linearity of the bottom line of the circuit after the pattern formation is poor (see FIG. 7), and the transmission loss is expected to be extremely large. As described above, it is understood that the present invention treatment can exhibit a high effect only when all the four-layer treatments described in the text are completed, and if it lacks even one layer, sufficient characteristics cannot be obtained as a copper foil for a high-frequency printed wiring board. I understand.

  The copper foil produced by using the surface treatment method of the present invention can obtain a strong peeling strength against a high-frequency substrate typified by a PPE resin-impregnated base material, and it has an ultra-low roughness, so a circuit by etching. Circuit bottom line linearity after circuit pattern formation by etching after pattern formation New copper foil for high-frequency printed wiring boards that can improve the linearity of the bottom line and greatly reduce transmission loss. As described above, it is considered that the present invention can sufficiently cope with applications in which thinning between circuit pitches is expected. In addition, since it has the characteristics that fine pattern, ultra-low roughness and appearance color tone can be black, it is also suitable for copper foil for electromagnetic wave shielding in plasma displays.

Cross section of surface treated copper foil Example 1 Surface treatment copper foil treated surface side electron micrograph of the present invention Example 5 Surface-treated copper foil treated surface side electron micrograph of the present invention Example 9 Surface treatment copper foil treated surface side electron micrograph of the present invention Comparative Example 5 Surface-treated copper foil treated surface side electron micrograph Example 1 Surface treatment copper foil circuit top surface electron micrograph of the present invention Comparative Example 5 Surface-treated copper foil circuit top surface electron micrograph

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Copper foil 2 ......... Roughening process layer 3 which consists of spherical fine roughening particle | grains ......... Heat resistant / rust prevention layer 4 ......... Chromate film layer 5 ......... Silane coupling agent layer

Claims (6)

  It has a roughening treatment layer composed of spherical fine roughening particles having a diameter of 0.05 to 1.0 μm on at least one surface of the copper foil, and molybdenum, nickel, tungsten, phosphorus, on the roughening treatment layer, It has a heat / rust preventive layer made of at least one of cobalt and germanium, and has a chromate film layer on the heat / rust preventive layer, and a silane coupling agent layer on the chromate film layer. A copper foil for a high-frequency printed wiring board, comprising:   2. The copper foil for a high-frequency printed wiring board according to claim 1, wherein the surface roughness Rz of the copper foil after the roughening treatment layer is formed is 2.5 μm or less.   A roughening treatment layer made of spherical fine roughening particles having a diameter of 0.05 to 1.0 μm is applied to at least one surface of the copper foil, and molybdenum, nickel, tungsten, phosphorus, cobalt is provided on the roughening treatment layer. Applying a heat / rust preventive layer comprising at least one of germanium, applying a chromate film layer on the heat / rust preventive layer, and applying a silane coupling agent layer on the chromate film layer. The manufacturing method of the copper foil for high frequency printed wiring boards characterized by these.   The electrolytic bath for forming a roughening treatment layer composed of spherical fine roughening particles having a diameter of 0.05 to 1.0 μm is a sulfuric acid / copper sulfate bath containing a sulfonate salt of an active organic sulfur compound. Item 4. A method for producing a copper foil for a high-frequency printed wiring board according to Item 3.   Electrolytic baths that form roughening treatment layers composed of spherical fine roughening particles having a diameter of 0.05 to 1.0 μm are sulfonates of active organic sulfur compounds, tungsten ions, molybdenum ions, cobalt ions, nickel ions, titanium ions. 4. The method for producing a copper foil for a high-frequency printed wiring board according to claim 3, wherein the sulfuric acid / copper sulfate bath contains at least one of the above. The sulfonate salt of the active organic sulfur compound in the electrolytic solution forming the roughened layer composed of spherical fine roughened particles having a diameter of 0.05 to 1.0 μm is represented by the general formula NaSO ₃ —R ₁ —SSR ₂ —SO _3. A symmetric or asymmetrical disulfide sulfonate represented by Na, or a thiol sulfonic acid represented by the general formula HS-R ₁ -SO ₃ Na or the general formula HS-Ar-SO ₃ Na A method for producing a copper foil for a high-frequency printed wiring board according to any one of claims 3 to 5. (Wherein R ₁ and R ₂ represent an alkylene group having 2 or 3 carbon atoms, and may be the same or different. Ar represents an aromatic group)

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