JP5129642B2 - Surface treated copper foil, copper clad laminate obtained using the surface treated copper foil, and printed wiring board obtained using the copper clad laminate - Google Patents

Description

  The present invention relates to a surface-treated copper foil, a copper-clad laminate obtained using the surface-treated copper foil, and a printed wiring board obtained using the copper-clad laminate.

  The surface-treated copper foil is bonded to an insulating resin base material to produce a copper-clad laminate that is a material for producing a printed wiring board. This surface-treated copper foil is a surface of the copper foil that has been subjected to surface treatment such as roughening treatment or rust prevention treatment for the purpose of improving adhesion with the insulating resin substrate and imparting storage stability. is there. The roughening treatment performed here is a treatment for improving the adhesion by using the anchor effect by forming rough shapes by attaching roughening particles to the surface or etching. And a rust prevention process is a process which improves the adhesiveness by providing the chemical adhesive effect of the bonding surface with an insulating resin base material other than provision of preservability.

  However, when a large uneven shape is formed by the roughening process to enhance the anchor effect, the overetching time required for dissolving the convex part of the roughening process is increased when the wiring circuit is formed by etching. There is a need to. As a result, it becomes difficult to form a fine wiring circuit having a good etching factor. In such a wiring circuit having a poor etching factor of the wiring circuit, it is often difficult to surface-mount components. Moreover, if a chemically stable rust prevention treatment is applied excessively, a rust prevention component remains on the surface of the insulating resin substrate after etching, which may cause a circuit short circuit due to surface layer migration. Therefore, it is necessary to set the roughening treatment and the rust prevention treatment to optimum levels suitable for the use of the printed wiring board as the final product.

  On the other hand, electronic devices, electrical products, and the like in which printed wiring boards are incorporated are remarkably required to be light and thin, and at the same time, there are many requests for high functionality. And it is requested | required that the printed wiring board obtained using surface-treated copper foil should be equipped with the fine wiring circuit excellent in the etching factor first. In response to this requirement, the surface-treated copper foil has been responded by low profile. Furthermore, if the profile is made low, the linearity of the end face of the wiring circuit is improved, and the electrical characteristics improve the high frequency characteristics, particularly the transmission characteristics in the frequency band of the GHz band. That is, it is recognized that it is preferable for increasing the clock frequency of the CPU or the like.

  By the way, in recent electronic devices, there is a tendency to frequently use multilayer printed wiring boards, and the frequency of processing once formed wiring circuits with chemicals is increasing. Therefore, the chemical resistance at the interface between the surface-treated copper foil and the base resin and the moisture absorption resistance of the exposed base resin are also important characteristics. And if the number of processing steps using a wiring board provided with a fine wiring circuit increases, the risk of the wiring circuit peeling off during handling increases. Therefore, when making the low profile of the adhesion surface of the surface-treated copper foil with the insulating resin base material, it is necessary to minimize the deterioration of various properties such as the peel strength and chemical resistance.

Therefore, Patent Document 1, for the purpose of roughness R _Z of Dohakuara of surface to provide a high copper foil and a method of manufacturing the adhesive strength be low, the roughened surface of the copper foil sample (S) From the three-dimensional surface area A (S) obtained by measuring the surface area of the three-dimensional surface with a laser microscope and the measurement area B (S) which is the area of the measurement area of the three-dimensional surface area A (S), A ( S) / B (S), the area coefficient C (S), and the roughness R _Z (S) of the roughened surface of the copper foil sample S measured using a stylus type roughness meter. 0.5 × R _Z (S) + 0.5 ≦ C (S) [wherein R _Z (S) is a numerical value in the unit μm. ] And a technique of employing a copper foil having a roughness R _Z (S) of 1.0 μm to 3.0 μm is disclosed.

  According to the example, the surface-treated electrolytic copper foil disclosed in Patent Document 1 has a thickness of 18 μm and an adhesive strength with the FR-4 base resin of 1.0 kgf / cm. That is, a certain level of contact area is ensured between the surface-treated copper foil and the insulating resin base material, while having a low profile level exceeding Type-V defined in the IPC standard as a copper foil for printed wiring boards. This ensures the adhesive strength.

JP 2005-290519 A

  However, the value of the peel strength cannot be an absolute index indicating the adhesion stability between the wiring circuit of the printed wiring board and the insulating resin base material. This is because it is difficult to guarantee the adhesion stability by the test method shown in the standard for printed wiring boards. In the test method indicated by the standard, the adhesive strength between the wiring circuit and the insulating resin base material is measured as a load necessary for peeling the wiring circuit from the insulating resin base material in the 90 ° C. direction. Specifically, the peel strength is measured by using a universal testing machine and recording the load required when a certain distance of the linear wiring circuit is peeled off on a continuous chart. The measurement chart obtained here is recorded with a certain amplitude, but the minimum value when the abnormal value is removed from the measurement chart recording is adopted as the peel strength. Therefore, as long as the minimum value is cleared, there is no problem with respect to the amplitude of the measurement chart and the presence of undulation with amplitude.

  However, considering the characteristics required for practical use, the adhesion stability between the wiring circuit and the insulating resin substrate is not only the normal peel strength but also the resistance to exhibit adhesion stability against chemical treatment. It should be discussed including the hygroscopic performance to show the adhesion stability against the moisture absorption of the resin base material in chemical performance, wet etching process and the like. According to the research and experience of the inventors of the present invention, a large amplitude is seen in the measurement chart of the peel strength in the normal state, and in the wiring circuit where the difference (amplitude) between the minimum value and the maximum value is large, the wiring The amplitude of the measurement chart of peel strength after chemical treatment of the circuit and after moisture absorption treatment tends to be further increased. That is, the wiring circuit having such a tendency is a wiring circuit in which adhesion deterioration due to chemical treatment or moisture absorption treatment is large, and is not practically preferable.

  Of the electrical characteristics of the wiring circuit, the transmission loss when transmitting a high-frequency signal is clearly affected by both the wiring circuit as a conductor and the insulating resin substrate as a dielectric. Further, it is known that the transmission loss caused by the wiring circuit is expressed as a function of the signal frequency, characteristic impedance, magnetic permeability, and specific resistance. However, even if the wiring circuit shape is the same, the characteristic impedance differs between the microstrip line and the strip line because the arrangement of the insulating resin base material is different. Therefore, in designing an actual printed wiring board, a simulation is performed in which the copper foil thickness, the insulating resin base material, the wiring circuit shape, and the like are specified. However, in order to obtain a printed wiring board having desired characteristics in actual manufacturing, design and trial manufacture evaluation are often repeated a plurality of times, which is a great restriction on delivery date management and cost management.

  Therefore, good linearity is obtained at the edge of the printed circuit formed on the printed wiring board, and the chemical resistance and moisture absorption resistance are good as well as adhesion to the insulating resin base material, and transmission of high frequency signals in the GHz band There has been a demand for a surface-treated copper foil that can make electrical characteristics close to design values, such as loss and characteristic impedance.

Surface-treated copper foil according to the present invention: The surface-treated copper foil according to the present invention has a surface roughness (Rzjis) of 2.5 μm or less and a two-dimensional surface area of 6550 μm. ^The surface area ratio (B), which is a value of the ratio [(A) / (6550)] of the three-dimensional surface area (A) μm ² and the two-dimensional surface area when the region ² is measured by a laser method, is 1.2 to 2 And the adhesive surface to be bonded to the insulating resin base material is an adhesive surface obtained by roughening the surface of the untreated copper foil with a surface roughness (Rzjis) before the roughening treatment of less than 1.0 μm. There, when the three-dimensional surface area 2-dimensional surface area measured by a laser method regions of 6550Myuemu ² before roughening treatment with (a) [mu] m ^2, after the roughening treatment two-dimensional surface area in the laser method an area of 6550Myuemu ² The measured value of the three-dimensional surface area (A The value of the ratio of the value (a) [(A) / (a)] is characterized by a 1.15 to 2.50.

In the surface-treated copper foil according to the present invention, the adhesive surface to be bonded to the insulating resin base material is indicated by a surface roughness (Rzjis) value measured at 10 points in a 10 cm × 10 cm two-dimensional region. The coefficient of variation (CV ₁ ) of the measured value of the surface roughness (Rzjis) after the treatment and the coefficient of variation (CV ₂ ) of the measured value of the surface roughness (Rzjis) before the roughening treatment of the untreated copper foil, It is also preferable that the bonding surface has a relationship of CV ₁ ≦ CV ₂ .

In the surface-treated copper foil according to the present invention, the adhesive surface to be bonded to the insulating resin base material is a total amount of zinc and nickel contained in the zinc-nickel alloy layer (C) in a two-dimensional evaluation of 10 cm × 10 cm (C It is also preferable that mg / m ² is 40 mg / m ² or more.

  In the surface-treated copper foil according to the present invention, the adhesive surface to be bonded to the insulating resin base material is the total amount of zinc and nickel contained in the zinc-nickel alloy layer (C) and the surface area ratio (B). The ratio [(C) / (B)] is preferably 30 or more.

Copper-clad laminate according to the present invention: A copper-clad laminate according to the present invention is obtained by bonding the surface-treated copper foil and an insulating resin base material.

Printed wiring board according to the present invention: The printed wiring board according to the present invention is obtained by using the copper-clad laminate.

Surface treatment copper foil according to the present invention, the surface roughness (Rzjis) is at 2.5μm or less, and, 2-dimensional surface area and the three-dimensional surface area (A) [mu] m ² when measured by a laser method regions of 6550Myuemu ² A surface area ratio (B), which is a value of the ratio [(A) / (6550)] to the two-dimensional surface area, is provided with an adhesive surface with an insulating resin substrate having a value of 1.2 to 2.5. Then, the surface roughness of the untreated copper foil before the roughening treatment (Rzjis) is less than 1.0 μm, and the surface roughness of the two-dimensional surface area of 6550 μm ² is measured by the laser method. When the three-dimensional surface area before treatment is (a) μm ² and the ratio of the value (A) to the value (a) [(A) / (a)] is 1.15 to 2.50 The transmission loss of a high-frequency signal having a frequency exceeding 10 GHz is smaller than that in the case of using a conventional copper foil for printed wiring boards, and variation is also reduced.

Form of surface-treated copper foil according to the present invention: The surface-treated copper foil according to the present invention has a “surface roughness (Rzjis) of an adhesive surface with an insulating resin base material of 2.5 μm or less and a two-dimensional surface area. 3D surface area when the area of 6550Myuemu ² was measured by a laser method (a) [mu] m ² and the ratio between the two-dimensional surface area [(a) / (6550) ] surface area ratio is a value (B) is 1.2 to 2.5 "and" The adhesion surface to be bonded to the insulating resin base material is an adhesion obtained by roughening the surface of the untreated copper foil having a surface roughness (Rzjis) before the roughening treatment of less than 1.0 μm. a surface, when the three-dimensional surface area 2-dimensional surface area measured by a laser method regions of 6550Myuemu ² before roughening treatment with (a) [mu] m ^2, the laser region 2 dimensional surface area of 6550Myuemu ² after the roughening treatment The value of the three-dimensional surface area (A The value of the ratio [(A) / (a) ] and the value (a) is one that meets the requirement of 1.15 to 2.50. "

  The surface roughness (Rzjis) is a 10-point average roughness defined in JIS standards, and the surface-treated copper foil according to the present invention has a surface roughness (adhesion surface with an insulating resin base material of 2.5 μm or less ( Rzjis). Even in the roughening treatment in which the roughened particles are adhered and formed on the surface of the smooth untreated copper foil by the electrolytic method, if the value of the surface roughness (Rzjis) is 2.5 μm or less, the current is extremely high. There are few portions where the roughened particles are formed in a concentrated manner, and there are also few portions where the roughened particles are deposited so as to overlap each other. In other words, there is little variation in the shape of the roughened particles formed by adhesion. And in order to ensure more stable peeling strength, chemical resistance, and moisture absorption resistance, it is more preferable that the surface roughness (Rzjis) is an adhesive surface of 1.5 μm to 2.4 μm.

Further, the ratio of the three-dimensional surface area (A) μm ² to the two-dimensional surface area when the region having a two-dimensional surface area of 6550 μm ^{2 on} the surface to be bonded to the insulating resin substrate is measured by a laser method [(A) / (6550 )] Is a surface area ratio (B) of 1.2 to 2.5. In consideration of forming a fine wiring circuit by a subtractive method of etching a copper foil, it is preferable to obtain a maximum contact area with a small amount of the roughening particles to be adhered and formed. From this viewpoint, it is preferable that the roughened particles have a substantially spherical shape. Assuming that the roughened particles are true spheres, when the surface area is measured by a laser method, the upper hemisphere is measured as the surface area of the sphere and the lower hemisphere is measured as a cylinder. Accordingly, it is considered that the surface area in the portion where the true sphere exists is four times the projected area.

  However, it is impossible to fill the adhesion surface with roughly spherical roughened particles, and the surface of the formed roughened particles is not smooth. Accordingly, the roughening particles after the roughening treatment are distributed with a certain distance. However, in a state where the surface area ratio value (B) is less than 1.2, the separation distance of the roughened particles is large and the distribution is sparse, and the shape of the roughened particles is difficult to obtain the anchor effect. There is a tendency to have shapes (eg, cones, hemispheres, etc.). As a result, a printed wiring board using such a surface-treated copper foil is not preferable because it becomes difficult to satisfy the adhesion, chemical resistance, moisture absorption resistance, etc. between the insulating resin substrate and the wiring circuit.

  On the other hand, when the surface area ratio value (B) exceeds 2.5, the particle size variation of the roughened particles formed by adhesion is large, and the roughened particles are formed close to each other, or a large roughening treatment is performed. A state in which small roughened particles are hidden between the particles can be seen. A large variation in particle size among the individual roughening particles is not preferable because it is difficult to shorten the overetching time when forming a wiring circuit by etching. From the above viewpoint, in order to guarantee more stable peeling strength, chemical resistance, and moisture absorption resistance, the value (B) should be an adhesive surface of 1.5 to 2.4. preferable.

  In order to deposit and form fine particles of metallic copper as the roughening particles, an electroplating method or an electroless plating method can be used. In the case of depositing using electroplating, the first stage treatment for depositing and forming fine roughened particles on the surface of the untreated copper foil and the adhesion of the finely roughened particles to the copper foil are strong. In general, the roughened particles are deposited and formed by two-stage copper plating including the second-stage treatment.

To form copper roughening particles by two-stage copper plating, first, in the first stage treatment, the copper concentration is 10 g / L to 25 g / L, and the free sulfuric acid concentration is 50 g / L to 150 g / L. In accordance with the above, a sulfuric acid-based copper electrolytic solution to which gelatin or the like is added as an additive is used, DSA is used as an anode, and electrolysis is performed under conditions of a liquid temperature of 20 to 30 ° C. and a cathode current density of 20 A / dm ^{2 to} 50 A / dm ² Then, the fine roughened particles are formed on the surface of the untreated copper foil. In the second stage treatment, a sulfuric acid-based copper electrolyte with a copper concentration of 45 g / L to 100 g / L and a free sulfuric acid concentration of 50 g / L to 150 g / L is used, DSA is used for the anode, and the liquid temperature is 30. Electrolytically at 50 to 50 ° C. and a cathode current density of 20 A / dm ^{2 to} 60 A / dm ² , and smoothly plating copper so as to wrap around the finely-roughened particles that have been adhered and formed. Into treated particles.

In the surface-treated copper foil according to the present invention, the adhesive surface to be bonded to the insulating resin base material is a rough surface having a surface roughness (Rzjis) before roughening treatment of the untreated copper foil of less than 1.0 μm. a treated adhesive surfaced, when the three-dimensional surface area 2-dimensional surface area measured by a laser method regions of 6550Myuemu ² before roughening treatment with (a) [mu] m ^2, the two-dimensional surface area after roughening treatment 6550Myuemu ² The ratio [(A) / (a)] of the value (A) to the value (a) of the three-dimensional surface area measured by the laser method must satisfy the condition of 1.15 to 2.50. is there.

  As described above, in the present invention, the roughening treatment is performed on the surface having an untreated copper foil with a surface roughness (Rzjis) of less than 1.0 μm. If the surface roughness (Rzjis) is less than 1 μm, the surface on which the roughened particles are adhered and formed may be a precipitation surface or a glossy surface, and the precipitation surface may be machined or chemically polished. Then, it may be a surface with a smooth surface. The reason why the surface roughness (Rzjis) is less than 1.0 μm is that the current in the electrolytic reaction is concentrated on abnormal protrusions and protrusions provided on the surface of the untreated copper foil, and the roughened particles are enlarged or locally. The first object is to prevent the formation of adhesion.

  In the surface-treated copper foil used for general purposes, the deposited surface of the electrolytic copper foil is roughened, and this deposited surface shows a form in which it is deposited in a chevron cone shape. The length (Rzjis) usually indicates 2 μm or more. When such a copper foil surface is subjected to a roughening treatment, the roughened roughening particles are attached and formed at the apex of the conical shape, and the roughening particles are hardly formed on the bottom and ridge portions of the conical shape. . When such a surface roughness (Rzjis) exceeds 1.0 μm, the roughened particles are concentrated and formed on abnormal protrusions or convex portions provided on the surface of the untreated copper foil. When the surface of the untreated copper foil exceeding the upper limit is observed with a scanning electron microscope, a surface state having undulations and irregular shapes is often observed.

  A second object of making the surface of the untreated copper foil subjected to the roughening treatment smooth and flat is to stabilize the electrical characteristics of a printed wiring board manufactured using the surface-treated copper foil. In order to maximize the characteristics of the electronic components mounted on the printed wiring board, as described above, it is important to reduce crosstalk and manage characteristic impedance as well as transmission loss. In addition, it is known that signals in the high frequency region are concentrated and propagated to the outer periphery of the wiring circuit due to the skin effect, and the thickness is calculated to be 2.1 μm at 1 GHz and 0.7 μm at 10 GHz. it can. That is, when a high-frequency signal exceeding 10 GHz is used, the propagation distance becomes long when propagating through a wiring circuit formed of an untreated copper foil having a surface roughness (Rzjis) exceeding 1 μm, and a signal deformed on the receiving side. A waveform will be obtained. Crosstalk is also said to be affected by the antenna effect exerted by the protrusions on the end face of the wiring circuit. Furthermore, large variations in the surface irregularities of the wiring circuit are directly connected to variations in wiring circuit resistance and impedance. Therefore, the use of untreated copper foil with a smooth surface can greatly contribute to the stabilization of the electrical characteristics of the printed wiring board.

Furthermore, the three-dimensional surface area before roughening treatment when the 2-dimensional surface area measured by a laser method regions of 6550Myuemu ² and (a) [mu] m ^2, and a 3-dimensional surface area after roughening and (A) [mu] m ² In this case, the ratio [(A) / (a)] between the value (A) and the value (a) is set to 1.15 to 2.50. This index indicates the level of roughening treatment. And when the value of [(A) / (a)] is less than 1.15, it is in the state where the favorable roughening process of a granularity is not performed uniformly. That is, since the anchor effect by the roughening process cannot be expected to be large, it is an undesirable roughening state. On the other hand, when the value of [(A) / (a)] exceeds 2.5, the roughening treatment is excessive, and the particle size of the roughening treatment particles that have been deposited increases or the precipitation roughening occurs. Either the deposited state of the treated particles becomes rough, or the particle shape tends to change from a substantially spherical shape to a dendritic shape. As a result, when forming a wiring circuit by the subtractive method, it is necessary to set a long over-etching time, which makes it difficult to form a wiring circuit having edges with good fine pitch and linearity, which is not preferable. .

Here, the manufacturing method of copper foil provided with the surface whose surface roughness (Rzjis) is less than 1.0 micrometer is described. The copper foil referred to here is described as including all rolled copper foil and electrolytic copper foil, but the surface roughness (Rzjis) in the case of rolled copper foil rarely exceeds 1.0 μm. Therefore, an example of the manufacturing method will be briefly described only with respect to the electrolytic copper foil. The electrolytic copper foil with a smooth surface has a copper concentration of 60 g / L to 100 g / L, a free sulfuric acid concentration of 50 g / L to 150 g / L, and an active sulfur compound sulfonate salt concentration of 5 mg / L to 1 g / L, a sulfuric acid-based copper electrolytic solution in which the concentration of a quaternary ammonium salt polymer having a cyclic structure is adjusted to 5 mg / L to 500 mg / L, and the chlorine concentration is adjusted to 10 mg / L to 100 mg / L. using, electrolyte temperature 40 ° C. to 60 ° C., is obtained such as by electrolysis at cathode current density ^{30A / dm 2 ~100A / dm 2} . The sulfonic acid salts of active sulfur compounds used as additives herein include 3-mercapto-1-propanesulfonic acid (hereinafter referred to as “MPS”) and bis (3-sulfopropyl) disulfide (hereinafter referred to as “SPS”). As the quaternary ammonium salt polymer having a cyclic structure, diallyldimethylammonium chloride (hereinafter referred to as “DDAC”) polymer or the like can be used.

Furthermore, in the surface-treated copper foil according to the present invention, the adhesive surface to be bonded to the insulating resin base material has a surface roughness (Rzjis) value measured at 10 locations in a 10 cm × 10 cm two-dimensional region. Variation coefficient (CV ₁ ) of the measured value of the surface roughness (Rzjis) after the roughening treatment, and variation coefficient (CV ₂ ) of the measured value of the surface roughness (Rzjis) before the roughening treatment of the untreated copper foil However, it has a relationship of CV ₁ ≦ CV ₂ . In the evaluation element described above, an area on the order of μm is evaluated that does not consider variation within the effective area of a printed wiring board that is actually used. However, an actual printed wiring board is processed with a size of several tens of centimeters. Accordingly, it is difficult to determine whether the roughening treatment, the rust prevention treatment, and the like are practically superior or inferior unless the variation when evaluated at a size of at least 10 cm × 10 cm is small. On the other hand, if it is a copper foil before roughening treatment, it can be made so that there is almost no difference in the evaluated characteristics at any place when it is divided and evaluated in units of 10 cm × 10 cm.

Here, let us consider a phenomenon in which the surface roughness (Rzjis) of the untreated copper foil before the roughening treatment is changed by the roughening treatment. First, it is assumed that particles having substantially the same shape are adhered and formed along the surface shape of the untreated copper foil in the roughening treatment step. Under this assumption, if the surface roughness (Rzjis) increases due to the adhesion of the roughened particles, the average value of the measured values of the surface roughness (Rzjis) measured at 10 points increases. And the variation (standard deviation) of the surface roughness (Rzjis) measured at 10 points also increases. However, if particles having substantially the same shape are adhered and formed, the degree of increase in standard deviation should be smaller than the degree of increase in average value. That is, a coefficient of variation (hereinafter referred to as “CV value”), which is a value of a ratio between standard deviation and average [(standard deviation) / (average value))] indicating variation, is not processed. It should be smaller than the CV value of the surface roughness (Rzjis) measured at 10 points of the copper foil. Therefore, when the CV value (CV ₁ ) of the surface roughness (Rzjis) of the roughened surface is smaller than the CV value (CV ₂ ) of the roughness (Rzjis) of the untreated copper foil surface, It becomes an index that can be determined that uniform roughening treatment is performed. Then, the surface treatment copper foil according to the present invention, an adhesive surface with the relationship CV ₁ ≦ CV _2.

  As described above, the printed wiring board obtained by using the surface-treated copper foil according to the present invention in which the surface area ratio of the adhesion surface with the insulating resin base material is within a predetermined range has a low transmission loss of high-frequency signals and a transmission loss. The variation of the is also reduced. As described above, the transmission loss of high-frequency signals cannot be considered without taking the skin effect into account. The high-frequency signal has a property that the dielectric constant flows toward a large direction. Therefore, in the microstrip line, the high-frequency signal propagates mainly on the insulating resin base material side. That is, in the characteristics of the copper foil that greatly affects the transmission loss in the microstrip line, the dependence on the surface shape of the copper foil adhesion surface is large, and the dependence on the linearity of the wiring circuit edge is large. Therefore, when the transmission loss is evaluated by the microstrip line, the influence of the adhesive surface of the surface-treated copper foil appears most clearly. In addition, the surface-treated copper foil according to the present invention has a nominal thickness of 18 μm by adhering the roughened surface of the surface-treated copper foil according to the present invention to an insulating resin substrate as shown in a later example. In the combination of the copper foil and the FR-4 base material, the transmission loss when a signal having a frequency of 10 GHz is transmitted via a microstrip line having a wiring circuit width of 220 μm can be reduced to 3.9 db / cm or less. That is, it shows a level clearly different from that of a conventional copper foil that has been conventionally used. This transmission loss tends to increase as the adhesion surface becomes rougher.

  Conventionally, it has been said that the evaluation of the electrical characteristics of a printed wiring board in a region exceeding the frequency of 10 GHz is unreliable, but recently, the reliability of measurement equipment has been improved and the reliability of measurement results has been improved. . Considering the reliability of the measurement result here, the determination is often made based on the reproducibility of the result of measuring the same part and the variation in data obtained from a plurality of measurement points. Therefore, this variation is a total of the variation of the measuring device and the test coupon. From this point of view, when using the copper foil for a printed wiring board that has been used for the general multilayer printed wiring board, not only the absolute value of the transmission loss is large but also the variation is large. Even if the printed wiring board is designed by trusting the evaluation result, it is difficult to actually manufacture the printed wiring board according to the design quality. Actually, when the surface roughness (Rzjis), which is an index for evaluating the adhesive surface of a conventional copper foil for printed wiring boards, is used as an index indicating the state of the adhesive surface, transmission loss increases as the surface roughness (Rzjis) increases. Even if the tendency to increase is grasped, the correlation between the surface roughness (Rzjis) and the transmission loss tends to be unclear near the surface roughness (Rzjis) exceeding 2.5 μm. However, when the surface area ratio according to the present invention is used as an index, the surface area ratio-transmission loss correlation is almost linear even for a surface-treated copper foil having a surface roughness (Rzjis) exceeding 2.5 μm. Show. In other words, since the surface-treated copper foil according to the present invention has a surface area ratio used as an index within an appropriate range, even if a test coupon for measurement is produced, the internal variation is small, and the reliability of measurement data of transmission loss is low. improves. Therefore, the surface-treated copper foil according to the present invention can create stable electrical characteristics according to the original design quality, for example, characteristic impedance and high-frequency transmission characteristics, with respect to a printed wiring board manufactured based on simulation. Surface-treated copper foil.

Furthermore, in the surface-treated copper foil according to the present invention, the adhesive surface bonded to the insulating resin base material is a total amount of zinc and nickel contained in the zinc-nickel alloy layer in the evaluation of a two-dimensional region of 10 cm × 10 cm. (C) mg / m ² is 40 mg / m ² or more. When the total amount of zinc and nickel is less than 40 mg / m ² , there is a portion where the coating of the copper foil surface with the zinc-nickel alloy is insufficient, and this portion has adhesiveness with the insulating resin substrate or Since it is inferior to chemical resistance, it is not preferable. The total amount of zinc and nickel of 40 mg / m ² is an amount capable of covering a completely flat ideal plane with a zinc-nickel alloy having a thickness of about 40 mm. The amount of the zinc-nickel alloy covering the ideal plane with a thickness of 40 mm is roughened with a surface area ratio of around 2 when there are finely-grained particles having a small shape variation on a substantially smooth surface. It is an amount that can be sufficiently covered, including the overhang portion provided in the surface roughening particles.

  The zinc-nickel alloy layer preferably contains 65 wt% to 90 wt% nickel and 10 wt% to 35 wt% zinc. Here, “wt%” indicates that the total of zinc and nickel is 100 wt% and that the presence of inevitable impurities is not considered. The nickel contained in the zinc-nickel alloy layer acts to prevent direct contact between the insulating resin base material and the metallic copper and stabilize the adhesion between the insulating resin base material and the copper foil. Generally, when metallic copper and base resin are in direct contact, the resin is altered (oxidized) by the catalytic action of copper, which is a noble metal, when heated. When the resin changes in quality, it adversely affects most properties such as adhesive strength, chemical resistance and moisture absorption resistance. Therefore, a zinc-nickel alloy layer containing nickel that is difficult to be alloyed with metallic copper is provided within the range of the thermal history received in the processing process of the printed wiring board, and functions as a barrier that prevents direct contact between copper and the insulating resin substrate. .

  However, if the nickel content exceeds 90%, it is difficult to completely dissolve and remove nickel even when treated with a copper etchant when forming a wiring circuit, which may cause surface layer migration. Absent. On the other hand, if the content ratio of zinc exceeds 35 wt%, the chemical resistance of the formed wiring circuit tends to be lowered, and when tin plating is performed, a phenomenon of precipitation of precipitated tin is likely to occur. In order to avoid both of the above phenomena, it is preferable that nickel contained in the zinc-nickel alloy layer be 70 wt% to 85 wt% and zinc be 30 wt% to 15 wt%.

In order to form the zinc-nickel alloy layer, for example, nickel sulfate is used to have a nickel concentration of 1 g / L to 3.5 g / L, and zinc pyrophosphate is used to have a zinc concentration of 0.1 g / L to 1 g / L. A nickel plating solution having a potassium pyrophosphate concentration of 50 g / L to 250 g / L and adjusted to pH 8 to 11 using potassium hydroxide can be used. With such a composition of the plating solution, the temperature of the plating solution is set to 20 to 50 ° C., the roughened surface of the copper foil is used as a cathode, an insoluble anode is used as a counter electrode, and electrolysis is performed at a current density of 0.3 to 10 A / dm ² . By doing so, a zinc-nickel alloy layer can be formed on the copper foil surface. However, depending on the plating apparatus, even within the above conditions, when the nickel concentration is high and the zinc concentration is low, the nickel content increases and the zinc content decreases. Further, when the zinc concentration is high and the nickel concentration is low, the zinc content tends to increase and the nickel content tends to decrease, and the optimal content ratio may not be obtained. Therefore, it is only necessary to conduct a preliminary test and select an optimum condition considering the characteristics of the apparatus.

  And in the surface-treated copper foil which concerns on this invention, the adhesive surface bonded with the said insulating resin base material is the value (C) of the total amount of zinc and nickel which the said zinc-nickel alloy layer contains, and the said surface area ratio ( The value of the ratio [(C) / (B)] to B) is 30 or more. As described above, the total amount of zinc and nickel must be such that the copper foil surface can be sufficiently covered with the zinc-nickel alloy. The surface area of the roughened surface that forms the zinc-nickel alloy layer is proportional to the value of the surface area ratio (B). Here, when the value of (B) is in the range of 1.2 to 2.5, if the value of [(C) / (B)] is 30 or more, the surface-treated copper foil has the roughened particles. The surface can be completely covered with a zinc-nickel alloy layer. If only adhesiveness, chemical resistance, etc. are used as criteria, there is no meaning to limit the upper limit of the value of [(C) / (B)]. However, if the total amount of zinc and nickel is excessive, it may be necessary to slightly increase the overetching time when forming a wiring circuit by etching. This is to prevent the occurrence of surface migration or the like. The upper limit of the value of [(C) / (B)] that is preferable from this viewpoint is around 50.

  Further, the surface of the zinc-nickel alloy layer can be subjected to a chromate treatment or a silane coupling agent treatment as necessary. In order to form the chromate layer, a substitution method, an electrolytic method, or the like can be employed. If a chromate layer is formed on the surface of the zinc-nickel alloy layer, adhesion to the insulating resin substrate and chemical resistance are improved. Furthermore, if the silane coupling agent is adsorbed on the surface, the wettability between the surface of the surface-treated copper foil and the insulating resin substrate can be improved. The type of silane coupling agent used here may be selected as appropriate in consideration of the type of insulating resin substrate. General-purpose silane coupling agents used to improve the adhesion between the resin and the inorganic substance include epoxy functional silane coupling agents, olefin functional silane coupling agents, acrylic functional silane coupling agents, and the like. is there. However, in the case of a polyimide resin, it is preferable to use an amino-functional silane coupling agent or a mercapto-functional silane coupling agent because a remarkable effect can be obtained. In order to adsorb the silane coupling agent on the surface of the surface-treated copper foil, an aqueous solution containing these silane coupling agents may be prepared and brought into contact with the surface of the surface-treated copper foil. For example, if the silane coupling agent is adsorbed only on the adhesion surface with the insulating resin substrate, a method of showering an aqueous solution containing the silane coupling agent on the roughened surface can be used.

Form of the copper clad laminate according to the present invention: The copper clad laminate according to the present invention is a copper clad laminate obtained by laminating the surface-treated copper foil according to the present invention and an insulating resin substrate. This copper clad laminate has roughened particles in which the surface-treated copper foil is finely and uniformly formed. Therefore, when manufacturing a printed wiring board, the copper clad laminate is easy to form a fine wiring circuit. It becomes a board. The formed wiring circuit has practically sufficient adhesion, is excellent in chemical resistance and moisture absorption resistance, and has excellent electrical characteristics. As mentioned above, because of the low transmission loss of high-frequency signals and the easy creation of characteristic impedance, this copper-clad laminate is suitable for use in the manufacture of package boards and other devices that directly mount semiconductor devices with a high clock frequency. Is preferred.

Printed wiring board according to the present invention: The printed wiring board according to the present invention is a printed wiring board obtained using the copper-clad laminate. That is, the printed wiring board according to the present invention makes use of the characteristics of the surface-treated copper foil according to the present invention using the above-described copper-clad laminate, and compared with a conventional general multilayer printed wiring board, The printed wiring board has a characteristic impedance as designed quality with little transmission loss of high-frequency signals.

  In Example 1, five types of surface-treated copper foils (Sample 1-1 to Sample 1-5) were prepared by subjecting a deposition surface of an untreated copper foil having a thickness of 9 μm to a roughening treatment and an antirust treatment, Various evaluations were performed. The conditions for the roughening treatment and the rust prevention treatment are shown in Table 1 later together with the conditions used in Comparative Example 1.

Production of untreated copper foil: An untreated copper foil having a thickness of 9 μm uses a sulfuric acid copper sulfate solution having the following composition as the copper electrolyte, a titanium rotating electrode as the cathode, and DSA as the anode. It was produced by electrolysis at a liquid temperature of 45 ° C. and a current density of 55 A / dm ² .

Copper concentration: 80 g / L
Free sulfuric acid concentration: 140 g / L
SPS concentration: 30 mg / L
DDAC polymer concentration: 50 mg / L
Chlorine concentration: 40mg / L

Surface roughness (Rzjis): The surface roughness (Rzjis) of the deposition surface of the untreated copper foil is a stylus type surface roughness meter (manufactured by Kosaka Laboratory Co., Ltd.) equipped with a diamond stylus whose tip r is 2 μm. , Trade name: SEF-30D) and measured according to JIS B 0601. As a result, as for the surface roughness (Rzjis), the average value of 10 measurement results was 0.7 μm, and the CV value (CV ₂ ) was 0.048. The evaluation results are shown in the following Table 2 together with the evaluation results of Example 1 and Comparative Example 1.

Three-dimensional surface area: The three-dimensional surface area is 2 of the deposition surface of untreated copper foil using an ultra-deep color 3D shape measuring microscope VK-9500 (used laser: violet laser with a visible light limit wavelength of 408 nm) manufactured by Keyence Corporation. Measurements were made on a region with a dimensional surface area of 6550 μm ² . As a result, the three-dimensional surface area was 6588 μm ² . The evaluation results are shown in Table 2 later together with the evaluation results of the sample 1-7 of Example 1 and a comparative example described later.

Roughening treatment: In the roughening treatment, two-stage electrolytic copper plating is performed in which finely roughened copper particles are adhered and formed in the first stage treatment, smooth plating is performed in the second stage treatment, and the shape of the roughened copper particles is adjusted. Carried out. First, in the first stage treatment, an untreated copper foil is used as a cathode in a first copper electrolytic solution in which the copper concentration is adjusted to 10 g / L, the free sulfuric acid concentration is adjusted to 100 g / L, and the liquid temperature is 30 ° C. The anode DSA was placed facing the deposition surface of the treated copper foil, and finely roughened copper particles were formed on the deposition surface of the untreated copper foil under each current condition described in Table 1 below.

  In the second stage treatment, the copper concentration is adjusted to 70 g / L, the free sulfuric acid concentration is adjusted to 150 g / L, the liquid temperature is 45 ° C., the copper foil is used as the cathode, The anode DSA was placed facing the deposition surface side, and smooth plating was applied to the deposition surface of the untreated copper foil on which the fine-roughened particles were adhered and formed under each current condition shown in Table 1 below. The shape of the chemical treatment copper particles was adjusted.

  After forming the roughened copper particles as described above, inorganic rust prevention treatment was performed on both sides of the copper foil. Specifically, the potassium pyrophosphate concentration was 80 g / L, the zinc concentration was 0.2 g / L, and the nickel concentration In a pyrophosphate rust-proof bath with a liquid temperature of 40 ° C., the copper foil as the cathode, and the SUS plates of the anode are arranged on both sides of the copper foil, and the copper foil is roughened. On the side, a zinc-nickel alloy layer was formed under each current condition described in Table 1 below.

Further, a chromate layer was formed by an electrolytic method. Specifically, in a 25 ° C. solution having a chromic acid concentration of 1 g / L and a pH of 11, a copper foil is used as a cathode, a SUS plate is used as an anode and the roughened surface is arranged to face a current density of 1 A / dm. ² was electrolyzed to form a chromate layer.

  When the chromate treatment was completed, it was washed with water, and a silane coupling agent was immediately adsorbed onto the rust preventive treatment layer on the precipitation surface side. Specifically, γ-glycidoxypropyltrimethoxysilane is dissolved in ion-exchanged water to prepare an aqueous solution having a concentration of 3 g / L, and this aqueous solution is showered so that the entire surface of the rust-preventing layer on the deposition surface is wet. Then, it was brought into contact with a roll to make the liquid film thickness uniform.

  When the silane coupling agent treatment is completed, the surface is kept in a drying furnace set to an atmosphere where the copper foil temperature becomes 150 ° C. for 4 seconds to disperse moisture, and 5 types of surface-treated copper foils having a thickness of 9 μm, Sample 1 -1 to Sample 1-5 were obtained.

Surface roughness (Rzjis) of adhesion surface: The surface roughness (Rzjis) of the adhesion surface of Sample 1-1 to Sample 1-5 was measured in the same manner as the deposition surface of the untreated copper foil. As a result, the average value of the measurement results at 10 locations was 1.5 μm to 2.3 μm, and the CV value (CV ₁ ) was 0.031 to 0.041.

Three-dimensional surface area: Similarly to the untreated copper foil, the three-dimensional surface area on the adhesion surface side of Samples 1 to 5 was measured. As a result, the three-dimensional surface area was 8216 μm ^{2 to} 11735 μm ² . Therefore, the value of B, which is the ratio to the measurement region having a two-dimensional surface area of 6550 μm ² , is 1.25 to 1.79, which is the ratio to the three-dimensional surface area of 6588 μm ² of the untreated copper foil [(A) / The value of (a)] was 1.25 to 1.78.

Composition of the alloy layer: The composition of the zinc-nickel alloy layer is protected with a dry film resist so that the glossy surface side does not dissolve, and after dissolving the 5 cm × 10 cm region of the adhesion surface with an oxidizing acid solution, pure water is added. The volume of the alloy component contained in the aqueous solution was analyzed using an ICP emission spectroscopic analyzer. The alloy component amount was calculated as the amount contained in a unit area of 1 m ² by converting the component concentration of the analysis result. The analysis results, the total amount of the amount of the zinc containing alloy layer is ^{10mg / m 2 ~13mg / m 2} , the amount of nickel ^{39mg / m 2 ~46mg / m 2} , zinc and nickel (C) is, 49 mg / M ^{2 to} 59 mg / m ² . Furthermore, when the value of the rust prevention amount [(C) / (B)] per three-dimensional surface area was calculated using this rust prevention amount (C), the value of (C) / (B) was 31 to 41. there were. The evaluation results are shown in Table 3 later together with the evaluation results of Comparative Example 1.

Adhesiveness: The adhesiveness of Sample 1 to Sample 5 with the insulating resin base material was evaluated by preparing an FR-4 copper clad laminate having a thickness of about 1.0 mm. Specifically, it is a book in which five FR-4 prepregs having a thickness of 0.18 mm are stacked and the roughened surface of the surface-treated copper foil is stacked so as to be in contact with the FR-4 prepreg side, This book was heat-press molded at 20 kgf / cm ² and 165 ° C. for 60 minutes to produce a single-sided copper-clad laminate.

  Next, after adjusting the copper foil surface of the single-sided copper-clad laminate, a negative dry film was laminated on the entire surface. A mask film for forming a wiring circuit shape for evaluation was placed on the dry film, exposed and developed, and the dry film in an unexposed portion was removed to form an etching resist. Next, the copper foil of the part which is not coat | covered with the etching resist was etched using the cupric chloride etching liquid. Further, the etching resist was peeled off by spraying with an aqueous NaOH solution to obtain a test coupon having a linear wiring circuit having a width of 0.2 mm for adhesion evaluation.

  The normal peel strength (hereinafter referred to as “P / SA”) of the test coupon was measured according to JIS C 6481 using a universal testing machine. As a result, P / SA was 0.81 kgf / cm to 0.96 kgf / cm, which was a practically sufficient value. The evaluation results are shown in Table 4 later together with the evaluation results of Comparative Example 1.

Chemical resistance: Evaluation of chemical resistance is based on the test coupon obtained above based on the change in peel strength before and after immersion in dilute hydrochloric acid (water: concentrated hydrochloric acid = 1: 1) at room temperature for 60 minutes. The acidity was evaluated. In a specific test method, the test coupon is immersed in dilute hydrochloric acid while being stirred, and after 60 minutes, the test coupon is taken out, immediately washed with water and air-dried, within the specified time, in the same manner as P / SA, The peel strength after hydrochloric acid treatment was measured. The hydrochloric acid resistance deterioration rate (%), which is an index of hydrochloric acid resistance, was calculated by dividing the difference between the peel strength after treatment with hydrochloric acid and P / SA by P / SA. As a result, the hydrochloric acid resistance deterioration rate was 0% to 4.0%, which was a good value. The evaluation results are shown in Table 4 later together with the evaluation results of Comparative Example 1.

Hygroscopic resistance: The hygroscopic resistance was evaluated based on the moisture resistance obtained from the change in peel strength before and after boiling the test coupon obtained above in ion-exchanged water for 120 minutes. In a specific test method, the test coupon is boiled in ion-exchanged water. After 120 minutes, the test coupon is taken out, washed with water, air-dried and cooled, and after boiling in the same manner as P / SA within a specified time. The peel strength was measured. The moisture deterioration rate (%), which is an index of moisture absorption resistance, was calculated by dividing the difference between the peel strength after boiling and P / SA by P / SA. As a result, the moisture deterioration rate was 0% to 3.0%, which was a good value. The evaluation results are shown in Table 4 later together with the evaluation results of Comparative Example 1.

  In Example 2, the transmission loss of the surface-treated copper foil having a thickness of 18 μm on which the roughened surface according to the present invention was formed was evaluated using a high frequency signal of 10 GHz. The surface-treated copper foil produced an untreated copper foil of 18 μm in the same manner as in Example 1, and the same treatment as Sample 1-4 of Example 1 was performed on the deposition surface (Rzjis: 0.6 μm) of the untreated copper foil. The surface treatment was performed under conditions. The surface roughness (Rzjis) after the surface treatment was 2.0 μm, and the surface area ratio (B) was 1.61, which was almost the same as Sample 1-4.

  Transmission loss is evaluated by double-sided copper-clad with a 15cm x 15cm size and 0.1mm plate thickness obtained by bonding the surface-treated copper foil to an FR-4 base material (GEPL-230TNT manufactured by Mitsubishi Gas Chemical Co., Ltd.) under recommended conditions. It implemented using the laminated board. In the test coupon 2 for evaluation, as in Example 1, a dry film was used as an etching resist, an unnecessary portion of the copper foil was etched away with a cupric chloride etching solution, and a wiring circuit having a width of 220 μm and a length of 150 mm was formed. Formed. The transmission loss was evaluated using a network analyzer manufactured by Anritsu Corporation. As a result, the transmission loss when using a high frequency signal of 10 GHz was 3.7 db / cm.

Comparative example

[Comparative Example 1]
In Comparative Example 1, Sample 1-6 using the same untreated copper foil as in Example 1, and Sample 1-7 using 9 μm-thick VLP copper foil manufactured by Mitsui Metal Mining Co., Ltd. as the untreated copper foil Was prepared by performing a surface treatment under the conditions described in Table 1, and the same evaluation as in Example 1 was performed. The average value of the surface roughness (Rzjis) measurement results of 10 precipitation surfaces of the VLP copper foil used for the production of Sample 1-7 was 2.0 μm, and the CV value (CV ₂ ) was 0.052. . Further, 2-dimensional surface area three-dimensional surface area measured for the area of 6550Myuemu ² was 8512Myuemu ^2. The processing conditions of Comparative Example 1 of this surface-treated copper foil are shown in the following Table 1 together with the processing conditions of Example 1, and the evaluation results related to the adhesive surface are combined with the evaluation results of Example 1 in the following table. It is shown in 2.

As a result of evaluating the sample 1-6 obtained above, the three-dimensional surface area after the surface treatment is 7300 μm ² , and the value of B, which is the ratio to the measurement region where the two-dimensional surface area is 6550 μm ² , is 1.11. The value of [(A) / (a)], which is the ratio of the untreated copper foil to the three-dimensional surface area of 6588 μm ² , was 1.11. The average value of the measurement results of the surface roughness (Rzjis) of 10 surfaces of the surface-treated copper foil bonded to the insulating resin base material was 1.3 μm, and the CV value (CV ₁ ) was 0.045. . In the analysis of the alloy layer on the bonding surface, the amount of zinc contained in the alloy layer is 12 mg / m ² , the amount of nickel is 38 mg / m ² , and the total amount (C) of zinc and nickel is 50 mg / m ² , the same It was almost equivalent to Example 1 which performed the antirust process on conditions. When this rust prevention amount (C) was used to calculate the value of the rust prevention amount per three-dimensional surface area [(C) / (B)], the value of (C) / (B) was 45. Further, P / SA in the FR-4 base material was 0.66 kgf / cm, the hydrochloric acid deterioration rate was 0.0%, and the moisture deterioration rate was 1.4%. The evaluation results are shown in Tables 2 to 4 later together with the evaluation results of Example 1 and Sample 1-7.

And as a result of evaluating sample 1-7, the three-dimensional surface area after the surface treatment is 13099 μm ² , and the value of B, which is the ratio of the two-dimensional surface area to the measurement region of 6550 μm ² , is 2.00, untreated copper foil The value of [(A) / (a)], which is the ratio to the three-dimensional surface area of 8512 μm ² , was 1.54. Moreover, the average value of the surface roughness (Rzjis) measurement result of 10 surfaces of the surface-treated copper foil bonded to the insulating resin base material was 3.2 μm, and the CV value (CV ₁ ) was 0.056. It was. In the analysis of the alloy layer on the adhesion surface, the amount of zinc contained in the alloy layer was 11 mg / m ² , the amount of nickel was 46 mg / m ² , and the total amount (C) of zinc and nickel was 57 mg / m ² . When this rust prevention amount (C) was used to calculate the value of the rust prevention amount per three-dimensional surface area [(C) / (B)], the value of (C) / (B) was 29. Further, P / SA of the FR-4 base material was 1.03 kgf / cm, the hydrochloric acid deterioration rate was 6.4%, and the moisture deterioration rate was 9.4%. The evaluation results are shown in Tables 3 to 4 below together with the evaluation results of Example 1 and Sample 1-6.

[Comparative Example 2]
In Comparative Example 2, transmission loss was evaluated in the same manner as in Example 2 using 8 types of surface-treated copper foils including non-roughened copper foils distributed in the market. The surface-treated copper foil evaluated in Comparative Example 2 had a surface roughness (Rzjis) of 0.4 μm to 4.3 μm and a surface area ratio of 1.0 to 2.36. And the transmission loss of the 10 GHz high frequency signal was 3.2 db / cm-4.2 db / cm.

<Contrast between Example 1 and Comparative Example 1>
As is clear from Table 2, the surface-treated copper foil obtained in the example has a surface roughness of the untreated copper foil in which the CV value (CV ₁ ) of the evaluation result of the surface roughness (Rzjis) of the roughened surface is untreated. (Rzjis) is smaller than the CV value (CV ₂ ) of the evaluation result. That is, it is shown that the roughened particles are uniformly deposited on the roughened surface of the example. Moreover, as seen in Table 4, P / SA in the FR-4 base material is also practically sufficient, and is a level that can be suitably used for printed wiring board applications. On the other hand, as can be seen in Table 4, Sample 1-6 of Comparative Example 1 has a low level of P / SA. And according to Table 2, the three-dimensional surface area of this surface-treated copper foil is as small as 7300 μm ^2, and the low P / SA results from insufficient formation of particles in the roughening treatment. I understand. Sample 1-7, as seen in Table 2, has a CV value (CV ₁ ) of 0.056 in the evaluation of the surface roughness (Rzjis) of the roughened surface, and is a VLP foil that is an untreated copper foil This is slightly larger than 0.052 of the CV value (CV ₂ ), and is the largest among the examples and comparative examples. The absolute value of the surface roughness (Rzjis) is also as large as 3.2 μm, and it is clear that there is a large variation in particle shape on the roughened surface. As a result, it can be determined that the effect of increasing P / SA in the FR-4 base material is not sufficiently obtained. Further, when Table 3 and Table 4 are compared, in Sample 1-7, the value of C / B is less than 30, so there is a portion where the surface coating with the zinc-nickel alloy is insufficient, and the chemical resistance It can also be seen that the moisture absorption resistance is poor.

<Contrast between Example 2 and Comparative Example 2>
Here, the correlation between the transmission loss indicated by the surface roughness (Rzjis), which is an evaluation index of the adhesion surface of the surface-treated copper foil, and the surface area ratio is compared. The relationship between the surface area ratio and the transmission loss is shown in FIG. 1, and the relationship between the surface roughness (Rzjis) and the transmission loss is shown in FIG. First, when the surface area ratio is used as an index, the correlation between the surface area ratio and the transmission loss shows a linear correlation over the entire surface-treated copper foil evaluated. However, when the surface roughness (Rzjis) is used as an index, the variation becomes large when the surface roughness (Rzjis) exceeds 2.5 μm, and no good correlation is observed. That is, it can be seen that even when a copper foil for a printed wiring board whose profile defined in the IPC standard is Type-V is used, a wiring circuit having good transmission characteristics cannot always be formed at a high frequency of 10 GHz. Therefore, it is clear from this comparison that the electrical characteristics of the printed wiring board are superior in the method of designing using the surface area ratio according to the present invention as an index.

Surface treatment copper foil according to the present invention, the surface roughness (Rzjis) is at 2.5μm or less, and, 2-dimensional surface area and the three-dimensional surface area (A) [mu] m ² when measured by a laser method regions of 6550Myuemu ² A surface area ratio (B), which is a value of the ratio [(A) / (6550)] to the two-dimensional surface area, is provided with an adhesive surface with an insulating resin substrate having a value of 1.2 to 2.5. Then, the surface roughness of the untreated copper foil before the roughening treatment (Rzjis) is less than 1.0 μm, and the surface roughness of the two-dimensional surface area of 6550 μm ² is measured by the laser method. When the three-dimensional surface area before the treatment is (a) μm ² and the three-dimensional surface area after the roughening treatment is (A) μm ² , the ratio of the value (A) to the value (a) [(A) / ( If the value of a)] is 1.15 to 2.50, it is easy to predict the transmission loss of the high-frequency signal. Therefore, in packaging applications where semiconductor devices are directly mounted, transmission when processing higher frequency signals is possible if the insulating resin base material having a smaller dielectric constant and dielectric loss tangent is bonded to the surface-treated copper foil according to the present invention. Loss can also be reduced. Furthermore, if the printed circuit board is designed by selecting the copper foil for the printed circuit board as an index of the surface area ratio, the electrical characteristics can reduce the difference between the design value and the actual product. As a result, it is possible to manufacture a printed wiring board in which electrical characteristics are incorporated with a small number of prototypes.

It is a figure which shows the relationship between a surface area ratio and transmission loss. It is a figure which shows the relationship between surface roughness (Rzjis) and transmission loss.

Claims (6)

A surface-treated copper foil for printed wiring boards,
Adhesive surface of laminating the insulating resin base material, the surface roughness (Rzjis) is at 2.5μm or less, and a three-dimensional surface area when the two-dimensional surface area measured by a laser method an area of 6550μm ² (A) μm ² The surface area ratio (B) which is the value of the ratio [(A) / (6550)] to the two-dimensional surface area is 1.2 to 2.5 ,
In addition, the adhesive surface to be bonded to the insulating resin base material is an adhesive surface obtained by roughening the surface of the untreated copper foil with a surface roughness (Rzjis) before the roughening treatment of less than 1.0 μm. when the three-dimensional surface area 2-dimensional surface area measured by a laser method regions of 6550Myuemu ² before the (a) [mu] m ^2, said 3-dimensional two-dimensional surface area measured by a laser method regions of 6550Myuemu ² after the roughening treatment A surface-treated copper foil , wherein the ratio [(A) / (a)] of the surface area value (A) to the value (a) is 1.15 to 2.50 . Measurement of the surface roughness (Rzjis) after the roughening treatment indicated by the value of the surface roughness (Rzjis) measured at 10 points in a 10 cm × 10 cm two-dimensional region on the adhesive surface to be bonded to the insulating resin substrate Bonding surface in which the coefficient of variation (CV ₁ ) of the value and the coefficient of variation (CV ₂ ) of the measured value of the surface roughness (Rzjis) before the roughening treatment of the untreated copper foil have a relationship of CV ₁ ≦ CV ₂ The surface-treated copper foil according to claim 1 . In the evaluation of a two-dimensional region of 10 cm × 10 cm, the adhesive surface to be bonded to the insulating resin base material has a total amount (C) mg / m ^{2 of} zinc and nickel contained in the zinc-nickel alloy layer of 40 mg / m ² or more. The surface-treated copper foil according to claim 1 or 2 . The adhesive surface to be bonded to the insulating resin base material is a ratio of the total amount of zinc and nickel contained in the zinc-nickel alloy layer (C) to the surface area ratio (B) [(C) / (B). ] The surface-treated copper foil in any one of Claims 1-3 whose value of is 30 or more. A copper clad laminate obtained by bonding the surface-treated copper foil according to any one of claims 1 to 4 and an insulating resin base material. A printed wiring board obtained by using the copper-clad laminate according to claim 5 .

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