JP4833556B2 - Surface treated copper foil - Google Patents

Description

  The present invention relates to a surface-treated copper foil having improved adhesion to a film mainly composed of an epoxy resin / polyimide resin and a thermoplastic liquid crystal polymer (hereinafter sometimes referred to as a liquid crystal polymer film). The present invention relates to a surface-treated copper foil for a flexible substrate, a multilayer substrate for high-density mounting, and a high-frequency circuit substrate obtained by laminating a treated copper foil and the film, and a circuit board formed using the surface-treated copper foil.

As electronic devices become smaller and lighter, various recent electronic components are highly integrated.
Substrate composites for manufacturing flexible boards, high-density mounting multilayer boards, high-frequency circuit boards, etc. (hereinafter sometimes collectively referred to as printed wiring boards) used in these are conductors (copper foil) and The insulating substrate is configured to support the insulating substrate, and the insulating substrate plays a role of ensuring insulation between the conductors and providing strength for supporting the components.
In addition, as the speed of the signal transmitted through the circuit board increases, the characteristic impedance and signal propagation speed of the insulating material constituting the circuit board become important, and the dielectric constant and dielectric loss of the insulating material are related. Improvement is required.

As a material for a substrate provided as an insulating material that satisfies these conditions, there are many phenol resin materials, and many epoxy resin materials are used in plated through holes. In recent years, an insulating material having a low dielectric constant and low dielectric loss is required for high-speed signal propagation, and a material for the same has been developed.
In addition, as a substrate requiring heat resistance, an insulating substrate such as a heat resistant epoxy resin or polyimide is used. In addition, materials with good dimensional stability, materials with less warping and twisting, materials with less heat shrinkage, and the like have been developed.

  Furthermore, a polyimide film is used when heat resistance is required for a flexible composite material for a substrate or when soldering is required. On the other hand, a polyester film is used in applications that do not use solder in printing carbon ink or the like. In recent years, flexible substrates and the like have become complicated, and in many cases, polyimide films have been used.

However, polyimide has a problem that the dielectric characteristics are greatly changed by water absorption, and the high-frequency characteristics are greatly deteriorated in a water absorption environment. In addition, while having high heat resistance, there is no heat melting property, so the composite with the copper foil as the conductor is imidized after casting the polyamic acid as the precursor on the copper foil, or on the polyimide film It is necessary to take a method such as laminating with a copper foil after providing an adhesive layer, and there is a problem that the process becomes complicated.
Therefore, liquid crystal polymers have attracted attention as thermoplastic materials having heat resistance that can withstand soldering because they have significantly lower hygroscopicity than polyimide and have little change in dielectric properties. However, the film made of this liquid crystal polymer has low adhesion to the copper foil, and the peel strength with the copper foil tends to be weaker than that of polyimide.

  The copper foil used as a conductive layer by being bonded to these insulating substrates is mainly an electrolytic copper foil. The electrolytic copper foil is usually made by an electrolytic foil making apparatus as shown in FIG. 1, and subjected to a roughening treatment or an antirust treatment for improving adhesion by a surface treatment apparatus shown in FIG.

  1 includes a rotating drum-shaped cathode 2 (the surface is made of SUS or titanium) and an anode 1 (lead or noble metal oxide-coated titanium electrode) arranged concentrically with the cathode. Then, an electric current is passed between both electrodes while the electrolytic solution 3 is circulated to deposit copper to a predetermined thickness on the cathode surface, and then the copper is peeled off from the cathode surface in a foil shape. The copper foil 4 at this stage is an untreated copper foil. The surface of the untreated copper foil in contact with the electrolyte is a matte surface, and the surface in contact with the rotating drum-shaped cathode 2 is a glossy surface (shiny surface).

  In order to increase the adhesive strength (peel strength) required for producing a copper-clad laminate by laminating an untreated copper foil 4 made of a foil, a surface treatment apparatus as shown in FIG. 2 is used. The untreated copper foil 4 is continuously subjected to electrochemical or chemical surface treatment. FIG. 2 shows an apparatus for continuously performing electrochemical surface treatment. An untreated copper foil 4 is continuously passed through an electrolytic layer filled with an electrolytic solution 5 and an electrolytic layer filled with an electrolytic solution 6. Then, surface treatment is performed using the electrode 7 as an anode and the copper foil itself as a cathode, and granular copper is deposited on the surface of the untreated copper foil 4 in order to improve adhesion when adhered to an insulating (resin) substrate. . This step is a roughening treatment step, and the roughening treatment is usually applied to the mat surface or shiny surface of the untreated copper foil 4. The copper foil after the surface treatment is the surface-treated copper foil 8 and is laminated with an insulating substrate to obtain a circuit board.

  However, among epoxy resins, polyimides, and liquid crystal polymers, particularly liquid crystal polymers are known as resins that are difficult to produce adhesive strength (peel strength) with copper foil. Generally, the peel strength of these resins and the copper foil is the copper foil surface roughness Rz (here, the surface roughness Rz is defined as "5.1 Ten Points" in JISB 0601-1994 "Definition and Display of Surface Roughness"). Rz defined in the definition of “average roughness”). When considering the surface roughness of the copper foil, the surface roughness Rz of the untreated copper foil and the Rz of the surface-roughened copper foil obtained by roughening the copper foil surface can be mentioned. Conventionally, in a smooth untreated copper foil, especially when increasing the peel strength for a resin that is difficult to peel, the current flowing during the roughening treatment is increased, and the amount of granular copper deposited during the roughening treatment is increased. A method of dealing with the problem by increasing the surface roughness Rz has been performed. Certainly, this method is suitable for the purpose of increasing the peel strength, but in the high frequency characteristics, it is not preferable that the surface roughness Rz is large or the amount of roughening particles is large due to the skin effect. .

Further, depending on the type of the liquid crystal polymer resin, there is a type of film in which no correlation is obtained in the peel strength even if the surface roughness Rz value of the surface-treated copper foil is increased. For such films, it has been found that the shape of the protrusions formed in the roughened particles is closely related.
Also, the circuit pattern on the printed wiring board is required to have a high density, and so-called fine pattern printed wiring boards formed with a circuit pattern having a fine line width and wiring pitch are required. . Recently, there has been a demand for a printed wiring board made of high-density ultrafine wiring having a wiring pitch of about 50 μm to 100 μm and a line width of about 30 μm. Increasing the surface roughness Rz in the roughened particles for increasing the peel strength and increasing the amount of adhesion are also unsuitable for these fine patterns. Although it is possible to increase the peel strength by roughening the surface of the untreated copper foil and reducing the amount of roughened particles attached, it is inappropriate for producing high-frequency characteristics / fine patterns.

  At present, as a copper foil having improved adhesion to a liquid crystal polymer, a copper alloy foil containing a specific element and provided with a surface oxide layer and a rust prevention layer having a specific thickness has been proposed (for example, see Patent Document 1). ). However, when the liquid crystal polymer is made into a film, the rod-shaped molecules are oriented in the plane direction, so the strength in the thickness direction is extremely reduced. Therefore, in the copper foil that does not perform such roughening, the liquid crystal polymer film is not bonded to the copper foil interface. As a result, sufficient peel strength cannot be obtained.

Further, in order to improve the adhesion of the liquid crystal polymer, methods for performing surface treatment such as plasma treatment (for example, see Patent Document 2), UV treatment (for example, see Patent Document 3) have been proposed. Even if this method is used, sufficient adhesiveness is not obtained for a copper foil having a low surface roughness.
Therefore, development of a copper foil that has good high frequency characteristics, can produce a fine pattern, and can increase peel strength is required.
JP 2003-064431 A JP 2001-049002 A JP 2000-233448 A

  The present invention has been made to solve such problems of the prior art, and since the epoxy resin / polyimide film generally used and the hygroscopic property are remarkably low, the change in dielectric characteristics is small, and the solder Surface-treated copper that has high heat resistance and can be laminated with copper foil by heating, but has high peel strength and fine patterning, compared to liquid crystal polymer resin, which is difficult to obtain peel strength. An object of the present invention is to provide a circuit board having good high-frequency characteristics by using the surface-treated copper foil.

  The present invention is a copper foil having a roughened surface by attaching roughened particles to at least one surface of a copper foil, the surface roughness of which is Rz: 1.5 to 4.0 μm, and the brightness value is 30 or less. This is a surface-treated copper foil.

In the present invention, in the surface treatment in which the surface-treated copper foil forms roughening on at least one surface of the untreated copper foil, the amount of copper or copper alloy to be adhered is 2.5 mg / dm ² or more and 400 mg / dm ² or more. It is a surface-treated copper foil which is dm ² or less.

  The surface-treated copper foil of the present invention is a copper foil having a roughened surface by attaching roughened particles to at least one surface of the copper foil, and the surface roughness is Rz: 1.5 to 4.0 μm. Yes, lightness value: 30 or less, the protrusions formed from the roughened particles have a height of 1 to 5 μm, and 200 to 25000 protrusions are distributed in an area of 100 μm × 100 μm. It is a surface-treated copper foil.

  Furthermore, the surface-treated copper foil of the present invention is a copper foil having a roughened surface by attaching roughened particles to at least one surface of the copper foil, and the surface roughness is Rz: 1.5 to 4.0 μm, Lightness value: 30 or less, the protrusions formed from the roughened particles have a height of 1 to 5 μm, and the density is distributed in the number of 6 to 35 in the range of the observation cross section of 25 μm. It is a surface-treated copper foil.

  Furthermore, the surface-treated copper foil of the present invention is a copper foil having a roughened surface by attaching roughened particles to at least one surface of an untreated copper foil, and the roughened surface has a surface roughness Rz. The surface brightness value at 1.5 to 4.0 μm is 25 or less, and the protrusion formed from the roughened particles is a protrusion having a height from the untreated copper foil surface of 1 μm to 5 μm, A surface-treated copper foil having a density of 6 to 35 in the range of 25 μm and a groove having a depth of 0.3 μm or more between the protrusions and being distributed substantially evenly. .

Furthermore, in the protrusions of the surface-treated copper foil, the maximum width of each protrusion is 0.01 μm or more, and is not more than twice the length obtained by dividing 25 μm by the number of protrusions existing in the 25 μm range. Is preferred.
Furthermore, this invention is the surface treatment copper foil whose copper foil before the roughening process of the said surface treatment copper foil is an electrolytic copper foil.
Furthermore, this invention is a surface-treated copper foil characterized by the electrolytic copper foil of an untreated copper foil consisting of a granular crystal.
Furthermore, this invention is a surface-treated copper foil whose roughness Rz of the surface which performs at least surface treatment of the untreated copper foil used for the said surface-treated copper foil is 2.0 micrometers or less.
Furthermore, the present invention is the surface-treated copper foil in which the surface on which the untreated copper foil is roughened is a matte surface having a surface roughness Rz of 2.0 μm or less.

Further, in the present invention, the protrusion of the surface-treated copper foil is at least one element selected from the group consisting of particles made of Cu, an alloy of Cu and Mo, or a group of Cu and Ni, Co, Fe, Cr, V, and W. A surface-treated copper foil characterized by being formed of alloy particles made of
Furthermore, the present invention is a surface-treated copper foil characterized in that a film made of Ni or a Ni alloy is formed on the surface of a projection formed of at least roughened particles of the surface-treated copper foil.
Furthermore, in the present invention, the surface-treated copper foil is provided with a rust-preventing layer comprising a zinc layer or a zinc alloy layer and / or a Cr metal layer or a chromate layer at least on the surface of a projection formed of roughened particles. It is the surface-treated copper foil characterized.
Furthermore, the present invention is the surface-treated copper foil in which the surface-treated copper foil has a silane coupling layer formed on at least the surface of the projection formed of roughened particles and / or a rust preventive layer.
Furthermore, this invention is a circuit board characterized by producing the circuit board using the said surface-treated copper foil.

The present invention is a surface-treated copper foil in which protrusions having a specific shape and distribution formed with roughened particles are formed on the surface of the copper foil, and the surface-treated copper foil is an insulating substrate, an epoxy resin / polyimide film・ Surface-treated copper foil capable of forming a fine pattern and having a high peel strength with respect to a liquid crystal polymer having heat resistance that can withstand soldering due to extremely low hygroscopicity, and the surface-treated copper foil In particular, a circuit board having a fine pattern and excellent high-frequency characteristics is provided.

  In the present invention, the copper foil before surface treatment (untreated copper foil) is a copper foil produced by electrolysis or rolling. The thickness of the copper foil is 1 μm to 200 μm, and at least one surface is preferably a copper or copper alloy foil having a surface roughness of Rz: 0.01 μm to 2 μm. Regarding the thickness of the copper foil, it is very difficult to roughen the surface of the copper foil having a thickness of 1 μm or less, and the copper foil used for the high-frequency printed wiring board is 200 μm. This is because the above foil is considered unrealistic.

As for the surface roughness of the untreated copper foil, a foil with Rz: 0.01 μm or less is practically difficult to manufacture, and even if it can be manufactured, it is actually unsuitable because it requires manufacturing cost, Although an untreated copper foil of Rz: 2.0 μm or more may be used, it is more preferable that the surface roughness of the untreated copper foil is 2 μm or less in view of high frequency characteristics and fine patterning.
In the present invention, the above-described untreated copper foil is subjected to surface treatment. The surface roughening treatment of the surface of the untreated copper foil is performed by attaching roughened particles to the surface of the untreated copper foil, and the surface roughness is a roughened surface of Rz: 1.5 to 4.0 μm.

The surface roughness of the roughened surface obtained by roughening the surface of the untreated copper foil and attaching the surface roughened particles to form protrusions is Rz of 1.5 to 4.0 μm. If Rz: less than 1.5 μm, the peel strength is low, so it is not satisfactory as a surface-treated copper foil that fulfills its purpose, and if Rz: greater than 4.0 μm, high-frequency characteristics are deteriorated and unsuitable for fine patterning. It is because it becomes.
Further, copper or copper alloy amount is deposited in the surface treatment performed on the untreated copper foil of the present ^{invention, 2mg / dm 2 ~400mg / dm} 2 is preferred. Is less than the amount of deposition is 2 mg / dm ² rather than satisfactory as a surface-treated copper foil to fulfill its purpose because peel strength is low, also larger than 400 mg / dm ^2, and unsuitable for fine patterning in terms of high frequency characteristics are degraded It is to become.

  In the present invention, the roughened copper foil subjected to the surface roughening treatment needs to have a brightness value of 30 or less. The lightness in the present invention is usually the lightness used as an index for viewing the roughness of the surface, and the measuring method is a method of measuring the amount of reflected light by applying light to the surface of the measurement sample and expressing it as a lightness value. is there. When the brightness of the treated surface of the surface-treated copper foil is measured by this method, when the surface roughness Rz is large or the depth of the groove between the roughened particles is deep, the lightness value is reduced because the amount of reflected light is reduced. When it is low and smooth, the amount of reflected light tends to increase and the brightness tends to increase. In order to improve the peel strength with the insulating substrate (liquid crystal polymer film), the brightness is preferably 30 or less. On the other hand, when the brightness is 31 or more, even if the roughened surface has a large Rz, the unevenness becomes gentle, so that the bite between the surface-treated copper foil and the insulating substrate (liquid crystal polymer film) is poor and the peel strength is not improved.

The brightness is measured on the copper foil to be measured.
Ni: 0.01 to 0.5 mg / dm ²
Zn: 0.01 to 0.5 mg / dm ²
Cr: 0.01 to 0.3 mg / dm ²
Then, the brightness was measured using a brightness meter (model name: SM color computer, model number SM-4, manufactured by Suga Test Instruments Co., Ltd.).

  The surface-treated copper foil of the present invention having both surface roughness (Rz) and brightness value as described above is laminated and combined with a liquid crystal polymer film to compensate for the drawbacks of the liquid crystal polymer film having a difficulty in adhesion, As will be apparent from Examples and Comparative Examples described later, a copper clad laminate having excellent peel strength and fine pattern characteristics can be provided.

  In the present invention, as described above, the surface of the untreated copper foil is roughened, but in order to obtain further excellent peel strength and fine pattern characteristics, the protrusions formed from the roughened particles described below It is preferable that the objects exist (distribute) substantially evenly. The height of the protrusion is preferably 1.0 μm to 5.0 μm. If the height of the protrusions formed on the surface of the untreated copper foil is 1.0 μm or less, the height is low, so the effect of increasing the peel strength cannot be obtained. If the height is 5.0 μm or more, the distribution of the protrusions is uniform. In addition, since the surface roughness Rz of the surface-treated foil varies widely from range to range, a stable peel strength cannot be maintained, high-frequency characteristics are deteriorated, and it is not suitable for fine patterning. is there. Here, the height refers to the distance between the surface of the untreated copper foil and the top of the protrusion.

If the number of protrusions is small, peel strength cannot be obtained. If the number is large, the adhesion between the copper foil surface and the protrusions is weak and the effect is reduced even if the number is large. In the present invention, as described above, the surface of the untreated copper foil is roughened, and the protrusions formed from the roughened particles in order to obtain a uniform peel strength on the surface have an in-plane of 100 μm × 100 μm. It is desirable that 200 to 25,000 are present in each. If the number of protrusions is less than 200, the gap between the protrusions is widened and a fine pattern cannot be formed, and if it is 25000 or more, the distance between the protrusions and the protrusions is narrowed and the peel strength is reduced. That is not preferable.
In the present invention, the number of protrusions is preferably 6 to 35 in an observation cross section of 25 μm, and particularly 10 to 20 is optimal.

  Here, the concept of protrusions existing in the observation cross section referred to in the present invention will be described. When the distance between the bottom of the groove formed between one protrusion and the protrusion adjacent to the protrusion and the apex of the protrusion (hereinafter sometimes referred to as groove depth) is less than 0.3 μm, Such a protrusion is grasped as one protrusion together with the adjacent protrusion, and when the groove depth is 0.3 μm or more, such a protrusion is also considered as an independent protrusion. Grasp as two protrusions. This groove depth refers to the distance between the surface of the untreated copper foil and the top of the protrusion, while the height of the protrusion described above is the distance between the bottom of the groove and the protrusion after the surface roughening treatment. It differs in the point of the distance from the vertex.

As a method of counting the number of protrusions, a method of counting the number of protrusions as defined above with a length of 25 μm by observing a cross-sectional SEM after embedding a surface-treated copper foil in a resin, polishing, and performing observation Is mentioned. The present invention lists the numbers measured using this method in the table of examples. Moreover, the schematic of cross-sectional observation was described in FIG.3, FIG.4, FIG.5.
Further, the number of protrusions having a height of 1.0 μm to 5.0 μm is 6 to 35 within 25 μm, and a groove having a depth of 0.3 μm or more is present between the protrusions. Distributing substantially evenly prevents the protrusions from being partially concentrated within 25 μm, and can stabilize the peel strength in the width direction and the longitudinal direction of the copper foil.

  In the present invention, “substantially evenly distributed” means “the number of protrusions whose height between the top of the protrusion and the copper foil surface is 1.0 μm to 5.0 μm is n ( When the observation width when the cross section of the protrusion is observed is 25 (μm), at least a part of the protrusion is present in the area of 25 / n (μm). I mean. "

In addition, in order to stabilize the peel strength, it is desirable that the width of the projections to be formed is uniform, and the maximum width of each projection is 0.01 μm or more and exists within a range of 25 μm. The width is preferably not more than twice the length obtained by dividing 25 μm by the number of protrusions. In addition, the maximum width here means the maximum value of the distance in the direction perpendicular to the height direction of the protrusion in the SEM observation of the cross section.
Further, regarding the groove depth between the protrusions, the average groove depth between the protrusions is more preferably 0.5 μm or more.

For the average groove depth between protrusions, the groove depth on both sides of each protrusion is measured for n protrusions with a groove depth of 0.3 μm or more, and the value at that time is A1 (μm) B1 (μm)... An (μm) When Bn (μm), it is a value obtained by the following equation.
((A1 + B1) +... + (An + Bn)) / 2 / n.

FIG. 3 is a view of an observation cross section of a surface-treated copper foil adapted to an embodiment of the present invention, the number of protrusions is 6 or more within 25 μm, and the height is in the range of 1 to 5 μm. The depth of the groove is 0.3 μm or more, and the maximum width of the protrusion is 0.01 μm or more, and the width is less than twice the length obtained by dividing 25 μm by the number of protrusions existing in the range of 25 μm. .
FIG. 4 is a cross-section in which some protrusions having a width not less than twice the length obtained by dividing 25 μm by the number of protrusions having a maximum width of 0.01 μm or more and 25 μm. FIG. 5 shows a cross section in which the protrusions are not evenly distributed.

  As described above, the surface-treated copper foil having the cross-sectional shape shown in FIG. 3 has good adhesion to the liquid crystal polymer film, and a fine pattern circuit configuration is possible. The surface-treated copper foil having a cross-sectional shape shown in FIG. 4 has a wide protrusion in part, and a portion having poor adhesion to the liquid crystal polymer film is present in part, which causes trouble in a high pattern circuit. However, it does not interfere with other general purposes. As shown in FIG. 5, when the protrusions are not evenly distributed, the adhesion with the liquid crystal polymer film is hindered, and there is a possibility that the circuit configuration of the fine pattern cannot be made.

The roughening particles forming the protrusions of the surface-treated foil of the present invention are at least one element selected from the group consisting of Cu, Cu and Mo alloy particles, or Cu and Ni, Co, Fe, Cr, V and W. Is included.
The desired projections can be obtained with Cu particles or alloy particles of Cu and Mo, but at least one element selected from the group of Ni, Co, Fe, Cr, V and W can be used as the Cu particles or alloy particles of Cu and Mo. Protrusions formed of two or more kinds of alloyed coarse particles containing, are more effective because they can form more uniform protrusions. It is considered that the roughened particles forming these protrusions increase the peel strength because chemical bonding is performed with the resin. Depending on the resin type, Cu-Mo alloy, Cu-Ni alloy, Cu-Co alloy, Cu-Fe alloy, Cu-Cr alloy, Cu-Mo-Ni alloy, Cu as particles that increase the peel strength by chemical bonding -Mo-Cr alloy, Cu-Mo-Co alloy, Cu-Mo-Fe alloy, etc. can be mentioned.

  At least one element selected from the group consisting of Mo, Ni, Co, Fe, Cr, V and W contained in the alloy particles forming the protrusions occupies 0.01 ppm to 20% with respect to the amount of Cu present. It is preferable. This is because an alloy composition with an abundance exceeding 20% is difficult to dissolve when a circuit pattern is etched in a subsequent process. Furthermore, in order to obtain uniform protrusions, the current density, liquid It is desirable to optimize the temperature and processing time.

In addition, at least one metal selected from the group consisting of Ni, Ni alloy, Zn, Zn alloy, and Ag is provided on the surface provided with the protrusions for the purpose of improving powder fall resistance, hydrochloric acid resistance, heat resistance, and conductivity. A plating layer may be provided. Furthermore, at least one metal plating layer of Ni, Ni alloy, Zn, Zn alloy, or Ag is attached to the surface on which the protrusion is not provided for the purpose of improving hydrochloric acid resistance, heat resistance, and conductivity. And good. In order to achieve these purposes, the amount of deposited metal is preferably 0.05 mg / dm ² or more and 10 mg / dm ² or less.
In particular, Ni metal or Ni alloy in liquid crystal polymer resin or the like has an effect of increasing peel strength.

  A Cr and / or chromate film is formed on the roughened surface foil having the above-described structure, and a rust prevention treatment is performed, or a silane coupling treatment or a rust prevention treatment + silane coupling is performed as necessary.

  As the insulating substrate, a film made of a composition containing 50% or more of an epoxy resin, a polyimide film, or a liquid crystal polymer is used. The liquid crystal polymer composition has a thermal expansion such as inorganic filler, polyethersulfone, polyamideimide, polyetherimide, polyetheretherketone, thermoplastic polyimide, etc. for the purpose of controlling linear expansion coefficient, improving adhesion, improving physical properties, etc. A plastic resin can also be mixed. However, when the content of the liquid crystal polymer is less than 50%, the properties of the liquid crystal polymer are lost in terms of low water absorption, heat resistance, dielectric properties and the like, which is not preferable.

  A composition containing 50% or more of the liquid crystal polymer used here (hereinafter simply referred to as a liquid crystal polymer) refers to a thermoplastic liquid crystal polymer that exhibits liquid crystallinity in a heated and melted state, exhibits liquid crystallinity in a solution, but undergoes heat melting. Lyotropic liquid crystal polymers such as non-aromatic polyamides are not used. A typical example of such a liquid crystal polymer is a wholly aromatic polyester obtained by homopolymerizing or copolymerizing aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol or the like as a monomer.

  As a method for laminating the liquid crystal polymer film as the insulating substrate and the surface-roughened copper foil, a hot press method, a continuous roll laminating method, a continuous belt press method, or the like is used, and thermocompression bonding is performed without using an adhesive or the like.

Hereinafter, the present invention will be described in more detail based on embodiments, but the present invention is not limited thereto.
In the present Example, what was described below was used as copper foil, the plating solution for roughening processes, and the film for insulating substrates.

(I) Copper foil:
(i) Raw foil 1
An untreated electrolytic copper foil and an untreated rolled copper foil having a thickness of 12 μm, a mat surface roughness of Rz = 1.26 μm, and a glossy surface roughness of Rz = 1.82 μm were prepared.
(ii) Raw foil 2
An untreated electrolytic copper foil having a thickness of 12 μm, a mat surface roughness of Rz = 1.52 μm, and a glossy surface roughness of Rz = 1.46 μm was prepared.
(iii) Raw foil 3
An untreated electrolytic copper foil having a thickness of 12 μm, a mat surface roughness: Rz = 1.86 μm, and a gloss surface roughness: Rz = 1.2 μm was prepared.

(B) Surface roughening plating solution and plating conditions:
(i) Electroplating A
・Plating bath 1
Copper sulfate (as Cu metal) 5-10 g / dm ³
Sulfuric acid 30-120 g / dm ³
Ammonium molybdate (as Mo metal) 0.1-5.0 g / dm ³
Current density 10-60A / dm ²
Energizing time 1 second-2 minutes Bath temperature 20-60 ° C
・Plating bath 2
Copper sulfate (as Cu metal) 20-70 g / dm ³
Sulfuric acid 30-120 g / dm ³
Current density 5-60A / dm ²
Energizing time 1 second to 2 minutes Bath temperature 20 ° C to 65 ° C

(ii) Electroplating B
・Plating bath 1
Copper sulfate (as Cu metal) 1-50 g / dm ³
Nickel sulfate (as Ni metal) 2-25g / dm ³
Ammonium metapanadate (as V metal) 0.1-15 g / dm ³
pH 1.0-4.5
Current density 1-60A / dm ²
Energizing time 1 second to 2 minutes Bath temperature 20 ° C to 60 ° C
・Plating bath 2
Copper sulfate (as Cu metal) 10-70 g / dm ³
Sulfuric acid 30-120 g / dm ³
Current density 5-60A / dm ²
Energizing time 1 second to 2 minutes Bath temperature 20 ° C to 65 ° C

(iii) Electroplating C
・Plating bath 1
Copper sulfate (as Cu metal) 1-50 g / dm ³
Cobalt sulfate (as Co metal) 1-50 g / dm ³
Ammonium molybdate (as Mo metal) 0.1-10 g / dm ³
pH 0.5-4.0
Current density 1-60A / dm ²
Energizing time 1 second to 2 minutes Bath temperature 20 ° C to 60 ° C
・Plating bath 2
Copper sulfate (as Cu metal) 10-70 g / dm ³
Sulfuric acid 30-120 g / dm ³
Current density 5-60A / dm ²
Energizing time 1 second to 2 minutes Bath temperature 20 ° C to 65 ° C

(iv) Electroplating A'B '(comparative example)
・Plating bath 3
Copper sulfate (as Cu metal) 20-70 g / dm ³
Sulfuric acid 30-120 g / dm ³
Current density 3A / dm ²
Energizing time 2 minutes or more (change time in surface roughness)
Bath temperature 15 ℃

(C) Film for insulating substrate:
(i) Liquid crystal polymer film (insulating substrate) 1 (hereinafter referred to as “Film 1”)
BIAC BA050F-NT, an I-type liquid crystal polymer film manufactured by Japan Gore-Tex Co., Ltd., was used.
(ii) Liquid crystal polymer film (insulating substrate) 2 (hereinafter referred to as “film 2”)
A type II liquid crystal polymer film, BIAC BC050F-NT, manufactured by Japan Gore-Tex Co., Ltd. was used.

In the surface treatment apparatus shown in FIG. 2 using the above-mentioned original foil 1 to original foil 3 as the copper foil, any one of the plating solution composition, bath temperature, and current condition ranges shown in the above electroplating solutions A to C The plating was performed at least once in the order of plating bath 1 → plating bath 2. Furthermore, Ni plating (0.3 mg / dm ² ) and zinc plating (0.1 mg / dm ² ) were applied to these roughened surfaces, and chromate treatment was performed thereon. In the case of the electroplating solutions A ′ and B ′, a comparative example foil was prepared using the solution composition and conditions of the plating bath 3 instead of the plating bath 2.
Table 1 shows the measurement results such as the surface roughness of the surface-roughened copper foil thus obtained, together with the surface treatment selection conditions.

Next, the surface-treated copper foil thus obtained was laminated with a liquid crystal polymer film (insulating substrate) as follows.
That is, the surface-treated copper foil obtained as described above and either the film 1 or the film 2 are laminated, and the film is obtained using a multistage vacuum press (Hot and Cold Press VH3-1377 manufactured by Kitagawa Seisakusho). In the case of 1, the film was held at 335 ° C. and 4 MPa, and in the case of the film 2 was held at 310 ° C. and 4 MPa for 5 minutes, then cooled and laminated to obtain a composite material for a substrate. The temperature was raised from room temperature at a rate of 7 ° C./min.

Further, as described below, a surface-treated copper foil was laminated using a polyimide film or an epoxy resin sheet instead of the liquid crystal polymer film to obtain a composite material for a substrate.
That is, the surface-treated copper foil prepared as described above was cut into a length of 250 mm and a width of 250 mm, and then a polyimide sheet (Ube Industries) having a thickness of 50 μm on the surface of the ultrathin copper foil (the surface on the roughened surface side). (UPILEX-VT) was placed, the whole was sandwiched between two smooth stainless steel plates, and thermocompression bonded at a temperature of 330 ° C. and a pressure of 2 kg / cm ² for 10 minutes by a vacuum press of 20 torr. It was created by thermocompression bonding at cm ² for 5 minutes.

In the case of an epoxy resin sheet, the surface-treated copper foil prepared as described above is cut into a length of 250 mm and a width of 250 mm, and then the surface on the roughened surface side is a sheet having a thickness of 1 mm after thermocompression bonding. It is placed on a glass fiber epoxy prepreg sheet (FR-4), sandwiched between two smooth stainless steel plates, thermocompression bonded at a temperature of 170 ° C. and a pressure of 50 kg / cm ² for 60 minutes, and FR- with a carrier foil. A single-sided copper-clad laminate for 4-carrier peel was prepared.

  The peel strength of the substrate composite material (copper-clad laminate) with the liquid crystal polymer film, polyimide film or epoxy resin sheet using the surface-treated foil thus obtained was measured. The peel strength was measured according to JIS C6471 by peeling in the 180 degree direction.

Further, the fine pattern characteristics of the prepared substrate composite were evaluated by the following methods.
That is, the prepared copper foil was attached to FR4 resin, and the copper foil resisted with line width: L and space width: S on the copper foil was etched with an iron chloride bath as shown in the schematic sectional view of FIG. The etching time when the top width of the line width L is the same as the resist width is determined, and each of the substrates resisted with each line width L and each space width S (10 lines formed on one substrate) is registered. n = 10 and etching is performed in the iron chloride bath for the above-determined time, and in each substrate, there is no bridge between the lines, or there is no root residue, or the top width of the line is equal to the resist. Observing that they were the same, the minimum L and S values were obtained among those substrates in which n = 10 were not observed.
Table 1 shows the results of peel strength and fine pattern characteristics evaluation performed under the conditions of the above Examples and Comparative Examples.

  As is clear from Table 1, the surface-treated copper foil in the examples and the surface-treated copper foil in the comparative example have a peel strength depending on the number of protrusions formed from the roughened particles and the lightness depending on the number even though the surface roughness is equal. Is clearly different, and it can be seen that the surface-treated copper foil of the example is improved. In Comparative Example 7, the peel strength increases as the roughness increases, but there is a defect that the fine pattern is not cut.

  The present invention is a surface-treated copper foil in which protrusions having a specific shape formed of roughened particles are formed on the surface of the copper foil, and an epoxy resin, polyimide film, liquid crystal as an insulating substrate on the surface-treated copper foil To provide a composite material for a substrate having good peel strength by using a polymer, excellent in heat resistance, capable of producing a fine wiring pattern, and excellent in high-frequency characteristics, and a circuit board using the same. And can be used in various fields of the electronic circuit component industry.

It is sectional drawing which shows the structure of an electrolytic foil manufacturing apparatus. It is sectional drawing which shows the structure of a surface treatment apparatus. It is a section observation schematic diagram of one embodiment of the surface treatment copper foil of the present invention. It is the cross-sectional observation schematic of other embodiment of the surface treatment copper foil of this invention. In surface treatment foil, it is a section observation schematic diagram showing the state where a projection is not distributed uniformly. It is explanatory drawing which shows the cross section after an etching.

Explanation of symbols

1 Electrolytic Foil Device Anode 2 Electrolytic Foil Device Cathode 3 Electrolytic Foil Device Electrolyte 4 Untreated Copper Foil
5 Electrolytic solution 6 of surface treatment device Electrolyte solution 7 of surface treatment device Anode 8 of surface treatment device Electrolytic copper foil (surface treatment copper foil)

Claims (9)

The copper foil before the roughening treatment of the surface-treated copper foil is an electrolytic copper foil made of granular crystals, and is a copper foil having a roughened surface by attaching roughened particles to at least one surface of the copper foil, and its surface Roughness Rz: 1.5 to 4.0 μm, lightness value: 30 or less, roughened surface, copper or copper alloy to be adhered in a surface treatment for forming a roughened surface on at least one surface of the untreated copper foil the amount is at 2.5 mg / dm ² or more 400 mg / dm ² or less of, the projections formed from roughening particles whose height is 1 to 5 [mu] m, the protrusion was within an area of 100 [mu] m × 100 [mu] m 200 Are distributed in a range of the observation cross section of 25 μm, and the number of the protrusions is approximately evenly distributed in the number of 6 to 35 , and the maximum width of each protrusion is 0.01 μm or more. Divide 25μm by the number of protrusions in the 25μm range Surface treated copper foil, characterized in that it is 2 times or less the length of the.   The surface-treated copper foil according to claim 1, wherein an average groove depth between the protrusions is 0.5 μm or more. 3. The surface-treated copper foil according to claim 1, wherein the surface-treated copper foil used for the surface-treated copper foil has a surface roughness Rz of 2.0 μm or less. The surface-treated copper foil according to claim 3 , wherein the surface of the untreated copper foil subjected to the roughening treatment is a matte surface having a surface roughness Rz of 2.0 µm or less. The protrusions of the surface-treated copper foil are formed of particles made of Cu or an alloy of Cu and Mo or alloy particles made of Cu and at least one element selected from the group of Ni, Co, Fe, Cr, V, and W. The surface-treated copper foil according to any one of claims 1 to 4 , wherein the surface-treated copper foil is formed. The surface-treated copper foil according to any one of claims 1 to 5 , wherein a film made of Ni or a Ni alloy is formed on a surface of a projection formed of at least roughened particles of the surface-treated copper foil. Claim 1, wherein said the surface of the projections formed at least roughening particles of surface treated copper foil, provided with a rust-preventive layer composed of a zinc layer or zinc alloy layer and / or Cr metal layer or chromate layer The surface-treated copper foil in any one of thru | or 6 . 8. The surface-treated copper foil according to claim 1 , wherein a silane coupling layer is formed on at least the surface of the projection formed of roughened particles and / or the rust preventive layer. Surface treated copper foil. A circuit board produced by using the surface-treated copper foil according to any one of claims 1 to 8 .

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