TW201404491A - Rolled copper foil, method for producing same, and laminate plate - Google Patents

Abstract

Provided are: a rolled copper foil that favorably adheres to resin, and is such that the resin transparency is excellent after the copper foil is removed by etching; a method for producing the rolled copper foil; and a laminate plate. The rolled copper foil is in a region bounded by the following formulae (1-4) in a graph having the 60 DEG glossiness (G) in a direction parallel to rolling on the x axis and the arithmetic mean obliquity (Deltaa) in a direction parallel to rolling on the y axis: G = 400 (formula 1); Deltaa = 0 (formula 2); Deltaa = (6.710-5)G + 0.025 (formula 3); and G = 800 (formula 4).

Description

Rolled copper foil, method of manufacturing the same, and laminated board

The present invention relates to a rolled copper foil, a method of manufacturing the same, and a laminated board, and more particularly to a rolled copper foil suitable for the resin which is required to be subjected to the remaining portion after etching the copper foil, a method for producing the same, and a laminated method thereof board.

In recent years, with the increase in the functionality of electronic devices, the high frequency of signals has been increasing. With this, flexible printed wiring boards (hereinafter referred to as FPCs), which are required to be used as signal wiring, can also be used in response to high frequencies. When the signal is high-frequency, the signal current is conducted near the surface of the wiring, so that if the surface of the copper foil used as the wiring member of the FPC is rough, the signal loss increases. Therefore, it is required to have surface smoothness in response to high frequency copper foil.

Further, when the FPC is bonded to the LCD and the ACF, the resin layer (for example, polyimide) which is the base of the FPC is used, and the mark position is confirmed by the CCD camera to be aligned with the bonding position. Therefore, if the transparency of the resin layer is low, the position cannot be aligned.

Regarding the resin layer of the FPC, after the copper foil and the resin layer are bonded, the copper layer is removed by etching. Therefore, the surface of the resin layer becomes a replica in which the unevenness of the surface of the copper foil is transferred. That is, if the surface of the copper foil is rough, the surface of the resin layer is also roughened, and the light is diffusely reflected, so that the transparency is lowered. Therefore, in order to improve the light transmittance of the resin layer, it is necessary to smooth the surface of the copper foil and the resin layer.

The roughening plating treatment is usually performed on the copper foil and the surface of the resin layer to increase the bonding strength. Since the plated particles of the roughening treatment are larger than the surface roughness of the copper foil, the surface of the copper foil is flattened The method of sliding has been mainly to improve the plating conditions so far.

As such a technique, for example, Patent Document 1 discloses a copper foil having an adhesion layer on the surface of a copper foil, which is formed of an ion or an oxide of chromium and zinc, and is treated with an aqueous solution containing at least 0.5% of decane.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-39126

However, the adhesion strength of the empirical sample disclosed in Patent Document 1 is inferior to the lower value in comparison with the rough copper foil as a comparative sample. As described above, when the roughened particles are excessively refined, the adhesion strength to the resin layer is lowered. Therefore, there is a limit to smoothing by roughening plating. Therefore, it is difficult to simultaneously ensure the adhesion strength between the resin layer and the copper foil and to improve the visibility of the resin layer.

An object of the present invention is to provide a rolled copper foil which is excellent in transparency of a resin after being subjected to etching and removal of a copper foil, and which has a smooth surface as compared with the conventional rough plating, and which can be satisfactorily adhered to the resin. Manufacturing method, and laminate.

As a result of the intensive research, the present inventors have found that the rolled copper foil which controls the glossiness and the arithmetic mean inclination by smoothing the surface of the rolled copper foil which is a base material of the rough plating by a predetermined means is used. Then, the resin can be satisfactorily adhered to, and the transparency of the resin after the copper foil is removed by etching is good.

The present invention based on the above findings is a rolled copper foil in which the X-axis is set to a 60-degree gloss G in a rolling parallel direction, and the Y-axis is set to an arithmetic mean tilt of a rolling parallel direction. In the graph of the degree Δa, it is located in a region surrounded by the following formulas 1 to 4.

Equation 1: G=400

Equation 2: △a=0

Equation 3: Δa = (6.7 × 10 ^-5 ) × G + 0.025

Equation 4: G=800

In one embodiment of the rolled copper foil of the present invention, the above formula 3 is Δa = 0.05.

In another embodiment of the rolled copper foil of the present invention, the above formula 1 is G = 500.

In still another embodiment of the rolled copper foil of the present invention, the copper foil and the polyimide film having a thickness of 25 μm are laminated at 300 ° C for 1 hour by hot pressing, and have a width of 3 mm or more and 5 mm or less. When the single-sided copper-clad laminate sample was subjected to 180° adhesion and bending on the inner side of the polyimide film surface, the number of times of bending until the copper foil was broken was three or more.

In still another embodiment of the rolled copper foil of the present invention, the number of times of bending until the copper foil is broken is five or more.

In another aspect of the invention, a method for producing a rolled copper foil, wherein the oil film equivalent in the final rolling pass of the final cold rolling step is set to be 17,000 or less, and the oil film in a rolling pass before the final rolling pass is performed. The equivalent is set to 15000 or less, and the oil film equivalent in the previous calendering pass is set to 10000 or less, and in the final cold rolling step, the gloss of 60 degrees is adjusted to 400 in the parallel direction of rolling immediately before the final calendering pass. After the above and Δa is 0.1 or less, the final rolling pass is performed.

In one embodiment, the method for producing a rolled copper foil according to the present invention is carried out by rolling using a calender roll having an average roughness Ra of 0.1 μm or less when measured in a direction parallel to the rotation axis of the roll.

According to still another aspect of the invention, there is provided a laminated board comprising a laminated copper foil of the present invention and a resin substrate.

According to the present invention, it is possible to provide a rolled copper foil which is excellent in transparency after resin removal by a resin and which is excellent in transparency after removal of a copper foil by etching, a method for producing the same, and a laminated sheet.

1 is a region in which the X-axis is a 60-degree gloss G in a rolling parallel direction, and the Y-axis is an arithmetic mean gradient Δa surrounded by the following formulas 1 to 4, and each of the examples and the comparative examples. A comparison of the locations of the evaluation results.

[Formation and Manufacturing Method of Rolled Copper Foil]

The rolled copper foil used in the present invention can be used as a rolled copper foil for forming a laminate with a resin substrate and partially removing the copper foil by etching.

In general, the roughening treatment is performed on the surface of the copper foil adjacent to the resin substrate, that is, the roughened surface, so as to improve the peeling strength of the copper foil after lamination, that is, the surface of the copper foil after degreasing is nodulated. Electrodeposition. This roughening treatment can be carried out by copper-cobalt-nickel alloy plating or copper-nickel-phosphorus alloy plating or the like.

The rolled copper foil of the present invention also contains a copper alloy foil containing one or more elements selected from the group consisting of Ag, Sn, In, Ti, Zn, Zr, Fe, P, Ni, Si, Te, Cr, Nb, and V. For example, it includes a copper alloy containing 10 to 2000 ppm of the above elements, preferably a copper alloy containing 10 to 500 ppm of the above elements. When the concentration of the above elements is increased (for example, 10% by mass or more in total), there is a case where the electrical conductivity is lowered. The electrical conductivity of the rolled copper foil is preferably 50% IACS or more, more preferably 60% IACS. More preferably, it is 80% IACS or more. Further, the thickness of the copper foil is not particularly limited, but is preferably 5 to 50 μm, more preferably 5 to 35 μm.

In the rolled copper foil of the present invention, the X-axis is set to a 60-degree gloss G in the direction parallel to the rolling, and the Y-axis is set as the arithmetic mean gradient Δa in the rolling parallel direction, and is surrounded by the following formulas 1 to 4. In the area.

Equation 1: G=400

Equation 2: △a=0

Equation 3: Δa = (6.7 × 10 ^-5 ) × G + 0.025

Equation 4: G=800

Here, the "arithmetic mean inclination Δa" is a value defined in JIS B0601-1994, and the curve is divided at a fixed interval ΔX, and the absolute value of the slope of the line segment connecting the start and end points of the measurement curve in each section is obtained. And average the value.

As described above, in the rolled copper foil of the present invention, first, the 60 degree gloss G of the rolling parallel direction is located in a region between the formula 1: G=400 and the formula 4: G=800. Therefore, the smoothness of the surface is good, and the rolled copper foil of the present invention is adhered to the resin layer and the resin layer after removal is excellent in visibility.

Further, in the case where the surface of the copper foil is smooth but there are sharp irregularities, the rough plating is excessively electrodeposited on the edge portion of the unevenness, so that the roughness after the roughening becomes uneven, and the visibility of the resin layer Not good. If the electrodeposition of the rough plating is reduced in order to prevent excessive electrodeposition on the uneven edge portion, the adhesion to the resin layer becomes poor. Therefore, the rolled copper foil of the present invention is located in the region between Equations 1 and 4, and is expressed by Equation 2 regarding the arithmetic mean inclination Δa: Δa = 0 and Equation 3: Δa = (6.7 × 10 ^-5 In the region surrounded by ×G+0.025, it is possible to control the sharp concavities and convexities of the surface of the material which is the starting point of the abnormal electrodeposition at the time of performing the plating treatment on the surface of the copper foil, and to ensure adhesion to the resin. In other words, in the periphery of the unevenness such as an oil pit on the surface of the copper foil, the tip current acts to excessively form rough particles during the roughening treatment, and abnormal electrodeposition occurs, which causes deterioration of the visibility of the resin layer. influences. On the other hand, if only the current conditions of the roughening treatment are reconsidered to suppress excessive formation of the roughened particles, the amount of the roughened particles is also reduced, and the adhesion to the resin layer is deteriorated. In order to solve such problems, in the present invention, by controlling the 60-degree gloss G in the parallel direction of the rolling, and controlling the arithmetic mean inclination Δa of the surface of the copper foil within the above range, the roughening particles in the roughening treatment can be prevented. The amount is reduced, and abnormal electrodeposition is also suppressed to be good.

Further, Formula 3 preferably has Δa = 0.05, more preferably Δa = 0.04.

Further, Formula 1 preferably has G = 450, and Formula 1 is more preferably G = 500.

Further, in consideration of productivity, etc., Formula 2 is preferably Δa = 0.001, preferably Δa = 0.002, more preferably Δa = 0.003.

The rolled copper foil of the present invention is preferably a single-sided copper-clad having a width of 3 mm or more and 5 mm or less which is obtained by pressure-bonding a copper foil and a polyimide film having a thickness of 25 μm at 300 ° C for 1 hour. When the laminate sample is subjected to 180° adhesion and bending on the inner side of the polyimide film surface, the number of times of bending until the copper foil is broken is three or more, and more preferably five or more. If the flexibility is as good as the above conditions, it can be preferably used as an FPC for an LCD module.

As a method for producing a rolled copper foil according to the present invention, first, a raw material is melted in a melting furnace to obtain a molten liquid having a desired composition. The melt is then cast into an ingot. Thereafter, it is suitably subjected to hot rolling, cold rolling, and annealing to form a foil having a predetermined thickness. After the heat treatment, the surface may be pickled, polished, or the like to remove the surface oxide film formed during the heat treatment. In the final cold rolling, the heat-treated material is passed through a calender to thereby form a predetermined thickness. In the method for producing a rolled copper foil of the present invention, it is important to finalize the final cold rolling step. The oil film equivalent in the rolling pass is set to 17,000 or less, the oil film equivalent in one rolling pass before the last rolling pass is set to 15000 or less, and the oil film equivalent in the previous rolling pass is set to 10000 or less, and finally In the cold rolling step, the final calendering pass is performed after the final calendering pass is adjusted to 60 degrees of gloss in the direction parallel to the rolling, and the gloss is 400 or more and Δa is 0.1 or less.

Here, the oil film equivalent is defined by the following formula.

Oil film equivalent={(calendering oil viscosity [cSt])×(passing speed [mpm]+rolling speed [mpm])}/{(rolling angle of the roller [rad])×(material's lodging stress [kg/mm] ² ])}

The rolling oil viscosity [cSt] is the dynamic viscosity at 40 °C.

In order to control the oil film equivalent, a known method such as using a low-viscosity rolling oil or slowing the passage speed may be employed.

By controlling the oil film equivalent, it is possible to use the roll to restrain the deformation of the surface of the material, and it is possible to suppress an increase in the surface roughness accompanying the thickness variation caused by the rolling. Further, the glossiness and Δa after the last pass can be controlled within a desired range by increasing the gloss and reducing Δa immediately before the final rolling pass. If the gloss is low immediately before the last pass, or if Δa is large, even if the surface of the material is smoothed in the last pass, the deep unevenness formed until the last time will remain. Obtain the desired surface shape.

Further, when the oil film equivalent is small, the unevenness of the surface of the calender roll used for calendering is easily transferred to the surface of the material, and therefore the surface of the calender roll is preferably smooth. Therefore, it is preferable that the calender roll used in the method for producing a rolled copper foil of the present invention has an average roughness Ra of 0.1 μm or less when measured in a direction parallel to the rotation axis of the roll.

The rolled copper foil of the present invention can be bonded to the resin substrate from the side of the roughened surface to produce a laminated body. The resin substrate is not particularly suitable as long as it has characteristics suitable for a printed wiring board or the like. Further, for example, a polyester film such as polyethylene terephthalate (PET) or a polyimide film, a liquid crystal polymer (LCP) film, or the like can be used.

As a bonding method, a copper foil may be laminated on a base material such as a polyimide film by using an adhesive or without using an adhesive under high temperature and high pressure, or the polyimide film may be coated on a rolled copper foil and dried. Hardening or the like, thereby producing a laminate.

[Examples]

Each of the rolled copper foils was prepared as described below as Examples 1 to 15 and Comparative Examples 1 to 9.

First, a copper ingot having the composition shown in Table 1 is produced, and after hot rolling, the annealing in the annealing furnace in which the cold rolling is performed at a temperature of 300 to 800 ° C is repeated one or more times, and then cold rolling is performed to obtain a thickness of 1 to 2 mm. Calendered sheet. The rolled sheet was annealed in an annealing furnace set at a temperature of 300 to 800 ° C to be recrystallized, and finally cold rolled until the thickness shown in Table 1 was obtained. In this case, in the final cold rolling step, the first embodiment has the oil film equivalent of 17,000 or less in the final calendering pass, and the oil film equivalent in a calendering pass before the final calendering pass is 15000 or less and the previous calendering pass. The rolling conditions are adjusted so that the oil film equivalent of the second time is 10000 or less, and the rolling conditions are adjusted so that the 60 degree glossiness and the Δa in the parallel direction of rolling are the values described in Table 1 immediately before the final rolling pass. get on. In Table 1, the oil film equivalent in the last calendering pass is described as "last pass oil film equivalent", and the oil film equivalent in one calendering pass before the final calendering pass is described as "the last pass before the oil film equivalent", before The oil film equivalent in a calendering pass is described as "the last two passes of the oil film equivalent".

Further, Comparative Examples 1 to 9 were subjected to final cold rolling under the conditions described in Table 1.

In addition, the calender roll used at this time is averaged in the direction parallel to the rotation axis of the roll. The roughness Ra is 0.08 μm.

The conditions of the roughening treatment were set as described below. The conditions for the roughening treatment are those generally used in FPC applications in which practically sufficient peel strength can be obtained.

. Plating bath composition: Cu 15g/L, Co 8.5g/L, Ni 8.6g/L

. Treatment pH: 2.5

. Processing temperature: 38 ° C

. Current density: 20A/dm ²

. Plating time: 2.0 seconds

Each of the samples of the examples and the comparative examples produced in the above manner was subjected to various evaluations as described below.

. Gloss:

The gloss of the copper foil before surface treatment was determined using a gloss meter Handy Gloss Meter PG-1 manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS Z8741 at an incident angle of 60 degrees in the rolling direction.

. Arithmetic mean slope △a

The arithmetic mean inclination Δa of the rolling parallel direction was obtained using the surface roughness measuring device Surfcorder SE-3400 of Kosaka Research Co., Ltd. according to JIS B0601-1994.

. Transparency (resin transparency):

One surface of each sample copper foil was subjected to a plating treatment under the following conditions as a roughening treatment.

. Plating bath composition: Cu 15g/L, Co 8.5g/L, Ni 8.6g/L

. Treatment pH: 2.5

. Processing temperature: 38 ° C

. Current density: 20A/dm ²

. Plating time: 2.0 seconds

Next, on both sides of a polyimide film (thickness 50 μm, UPILEX manufactured by Ube Industries, Ltd.) with a thermosetting adhesive for lamination, the roughened side of the roughened copper foil was bonded and etched ( The copper chloride solution was removed to form a sample film. A printed matter (black circle having a diameter of 6 cm) was adhered to one surface of the obtained resin layer, and the light transmittance of the printed matter was judged from the opposite surface via a resin layer. When the length of the black circle of the printed matter is more than 90% of the circumference, the length is clearly "◎", and the outline of the black circle is 80% or more of the circumference and the length of less than 90% is clearly defined as "○", black The contour of the circle is more than 60% of the circumference and less than 80% of the length is clearly judged as "△" (all above are qualified), and the contour of the black circle is 0 to 60% of the length of the circle is not clear and the contour is out of shape. The evaluation is "X" (failed).

. Peel strength (follow strength):

According to PC-TM-650, the normal peel strength was measured using a tensile tester Autograph 100, and those having a normal peel strength of 0.7 N/mm or more were evaluated as those which can be used for laminated substrates.

. Flexibility

A single-sided copper-clad laminate sample having a width of 3 mm or more and 5 mm or less, which was obtained by pressure-bonding each copper foil and a polyimide film having a thickness of 25 μm at 300 ° C for 1 hour, was used for the polymerization. When the imide film surface was 180° in close contact with the inner side, the number of bends until the copper foil was broken was measured.

. Abnormal electrodeposition

Using a scanning electron microscope (SEM: Scanning Electron Microscope), three or more portions randomly selected from the field of 10 μm square of the roughened surface were observed, and the electrodeposited particles having a long diameter of more than 1 μm of the roughened particles were observed. When the number of the average is one/100 μm ² or less, it is evaluated as "0" without abnormal electrodeposition, and when more than one and three or less/100 μm ^{2 are} evaluated, the abnormal electrodeposition "△" is evaluated, and it is more than three /100 μm. The case of ² was evaluated as having an abnormal electrodeposition "X".

The conditions and evaluation of each test described above are shown in Table 1.

(Evaluation results)

In Fig. 1, "the X-axis is a 60-degree gloss G in a rolling parallel direction, and the Y-axis is an area surrounded by the following formulas 1 to 4 in the graph of the arithmetic mean inclination Δa" and "Example 1~ Comparison of the position of each of the evaluation results of 15 and Comparative Examples 1 to 9.

Equation 1: G=400

Equation 2: △a=0

Equation 3: Δa = (6.7 × 10 ^-5 ) × G + 0.025

Equation 4: G=800

In the first to fifteenth embodiments, the X-axis is set to the 60-degree gloss G in the rolling parallel direction, and the Y-axis is set to the arithmetic mean inclination Δa, and both are located in the region surrounded by the above formulas 1 to 4, and The adhesiveness of the resin, the visibility of the resin, and the flexibility are good. In Examples 5, 6 and 9 in which the arithmetic mean inclination Δa was larger than 0.05, the abnormal electrodeposition was more than that in the other examples, and the light transmittance of the resin was lowered. In particular, in Example 5 in which the gloss was low, the light transmittance was Δ.

In Comparative Examples 1 to 9, in the graph in which the X-axis is a 60-degree gloss G in the rolling parallel direction and the Y-axis is an arithmetic mean gradient Δa, both are located outside the region surrounded by the above formulas 1 to 4, and the resin The visibility is not good. In addition, there are also adhesions to resins and poor bendability.

In Comparative Example 1, the oil film equivalents before the last pass, the last pass, and the last two passes were large, the gloss was lowered, and Δa was increased. In Comparative Examples 2, 4 and 8, the oil film equivalent in the last pass was large, and thus the gloss was lowered. In Comparative Examples 5 and 6, the oil film equivalent before the last two passes was large, and Δa became large. In Comparative Example 3, the oil film equivalent before the last two passes and the last one pass was large, and Δa became large. In Comparative Examples 7 and 9, the oil film equivalent of the last two passes and the last pass was large, and the gloss was lowered. Further, in Comparative Example 9, further Δa also became relatively large.

Claims (8)

A rolled copper foil having a 60-degree gloss G in a rolling parallel direction and a Y-axis as an arithmetic mean gradient Δa in a rolling parallel direction, and is located in an area surrounded by the following formulas 1 to 4. Medium: Formula 1: G=400 Formula 2: Δa=0 Equation 3: Δa = (6.7 × 10 ^-5 ) × G + 0.025 Formula 4: G = 800. The rolled copper foil according to claim 1, wherein the formula 3 is Δa=0.05. The rolled copper foil of claim 1, wherein the formula 1 is G=500. The rolled copper foil according to the first aspect of the invention, wherein the copper foil and the polyimide film having a thickness of 25 μm are laminated at 300 ° C for 1 hour by hot pressing, and have a width of 3 mm or more and 5 mm or less. When the single-sided copper-clad laminate sample was subjected to 180° adhesion and bending on the inner side of the polyimide film surface, the number of times of bending until the copper foil was broken was three or more. The rolled copper foil according to item 4 of the patent application, wherein the number of times of bending until the copper foil is broken is five or more times. A method for producing a rolled copper foil, wherein the oil film equivalent in the final rolling pass of the final cold rolling step is 17,000 or less, and the oil film equivalent in a rolling pass before the final rolling pass is set to 15000 or less, which is further The oil film equivalent in the rolling pass is set to 10000 or less, and in the final cold rolling step, after the final calendering pass is adjusted to 60 degrees of gloss in the parallel direction of rolling, the glossiness is 400 or more and Δa is 0.1 or less. Finally, the pass is delayed. A method for producing a rolled copper foil according to item 6 of the patent application, wherein a calender roll is used The average roughness Ra when the calender roll is measured in a direction parallel to the rotation axis of the roll is 0.1 μm or less. A laminated board comprising a rolled copper foil according to any one of claims 1 to 5 and a resin substrate.