JP2014011451A - Rolled copper foil, process of manufacturing the same, and laminate sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolled copper foil excellently bondable to a resin, and excellent in transparency of the resin after removing a copper foil by etching, and to provide a process of manufacturing the rolled copper foil and a laminate sheet.SOLUTION: The rolled copper foil has the 60-degree glossiness G larger than 500 in a direction parallel to the rolling, wherein, when a sample of a one-sided copper-clad laminate sheet of a width of 3 mm or larger and 5 mm or smaller, formed by laminating the copper foil and a polyimide film of 25 μm thick is contact-bent by 180° with the polyimide film to come inside, the number of bends until the copper foil is broken is equal to 3 or more.

Description

  TECHNICAL FIELD The present invention relates to a rolled copper foil and a method for producing the same, and a laminated board, and in particular, a rolled copper foil suitable for a field where transparency of the remaining resin after etching the copper foil is required, and a method for producing the same. , Relating to laminates.

In recent years, with the increase in functionality of electronic devices, the frequency of signals has been increased, and accordingly, flexible printed wiring boards (hereinafter referred to as FPC) used as signal wiring have been required to support high frequencies. When the frequency of the signal is increased, the signal current propagates near the surface of the wiring. Therefore, if the surface of the copper foil used as the FPC wiring member is rough, the signal loss increases. Therefore, the smoothness of the surface is required for the high-frequency copper foil.
Further, when the FPC is bonded to the LCD by the ACF, the marker position is confirmed by a CCD camera through a resin layer (for example, polyimide) serving as the base of the FPC, and the bonding position is adjusted. For this reason, if the transparency of the resin layer is low, alignment cannot be performed.
The resin layer of FPC is obtained by removing the copper layer by etching after bonding the copper foil and the resin layer. Therefore, the resin layer surface is a replica to which the unevenness of the copper foil surface is transferred. That is, if the surface of the copper foil is rough, the surface of the resin layer is also rough, and light is irregularly reflected, so that the transparency is lowered. For this reason, in order to improve the light transmittance of a resin layer, it is necessary to make the adhesive surface with the resin layer of copper foil smooth.
In general, the adhesive surface of the copper foil with the resin layer is subjected to roughening plating in order to increase the adhesive strength. Since the plating particles for the roughening treatment are larger than the surface roughness of the copper foil, the plating conditions have been mainly improved so far as means for smoothing the copper foil surface.

  As such a technique, for example, Patent Document 1 discloses an adhesion layer that is formed of chromium and zinc ions or oxides on the surface of a copper foil and is processed using an aqueous solution containing at least 0.5% of silane. The copper foil is shown.

JP 2012-39126 A

However, the adhesion strength of the demonstration sample disclosed in Patent Document 1 is lower than that of a rough copper foil as a comparative sample. As described above, when the coarse particles are excessively refined, the adhesion strength with the resin layer is lowered, and thus there is a limit to smoothing by improving the rough plating. For this reason, it is difficult to achieve both ensuring of the adhesion strength between the resin layer and the copper foil and improving the visibility of the resin layer.
The present invention is a rolled copper having a smooth surface even when subjected to the same roughening plating as before, excellent adhesion to the resin, and excellent transparency of the resin after the copper foil is removed by etching. It is an object to provide a foil, a manufacturing method thereof, and a laminated board.

  As a result of intensive research, the inventors smoothed the surface of the rolled copper foil as a base material for rough plating by a predetermined means, and by using the rolled copper foil whose gloss level was controlled within a predetermined range, It has been found that the transparency of the resin after removing the copper foil by etching is improved even when a roughening treatment for obtaining good adhesion with the resin is performed.

  The present invention completed on the basis of the above knowledge is, in one aspect, a rolled copper foil having a 60-degree glossiness G in the rolling parallel direction of more than 500, and the copper foil and a polyimide film having a film thickness of 25 μm are laminated. When the single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less was subjected to 180 ° contact bending with the polyimide film surface inside, the number of times of bending until the copper foil was broken was 3 times or more. A rolled copper foil.

  In one embodiment of the rolled copper foil according to the present invention, the 60 degree gloss G in the rolling parallel direction is 600 or more.

  In another embodiment of the rolled copper foil according to the present invention, the 60-degree glossiness G in the rolling parallel direction is 900 or less.

  In another embodiment of the rolled copper foil which concerns on this invention, the frequency | count of bending until the said copper foil fractures | ruptures is 5 times or more.

  In another aspect of the present invention, the oil film equivalent in the final rolling pass of the final cold rolling process is 17000 or less, the oil film equivalent in the rolling pass immediately before the final rolling pass is 15000 or less, and the oil film equivalent in the rolling pass immediately before is further reduced. The rolled copper foil of the present invention is subjected to the final rolling pass after being adjusted so that the 60 ° gloss in the rolling parallel direction is greater than 500 immediately before the final rolling pass in the final cold rolling step. It is a manufacturing method.

  In one embodiment of the method for producing a rolled copper foil of the present invention, rolling is performed using a rolling 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.

  In still another aspect of the present invention, the present invention provides a laminated plate configured by laminating the rolled copper foil of the present invention and a resin substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the rolled copper foil excellent in the resin transparency after adhere | attaching resin favorably and removing copper foil by an etching, its manufacturing method, and a laminated board can be provided.

3 is a SEM image of the copper foil surface of Example 2. 6 is a SEM image of a copper foil surface of Comparative Example 2.

[Form and manufacturing method of rolled copper foil]
The rolled copper foil used in the present invention is useful for a rolled copper foil that is used by bonding a resin substrate to produce a laminate and partially removing the copper foil by etching.
Usually, the surface of the copper foil that adheres to the resin substrate, that is, the roughened surface, has a fist-like electric surface on the surface of the copper foil after degreasing in order to improve the peel strength of the copper foil after lamination. A roughening process is carried out to wear. This roughening treatment can be performed by copper-cobalt-nickel alloy plating, copper-nickel-phosphorus alloy plating, or the like.
The rolled copper foil according to the present invention includes a copper alloy foil containing one or more elements such as Ag, Sn, In, Ti, Zn, Zr, Fe, P, Ni, Si, Te, Cr, Nb, and V. For example, a copper alloy containing 10 to 2000 ppm of the above element or a copper alloy containing 10 to 500 ppm is included. When the concentration of the above elements increases (for example, 10% by mass or more in total), the conductivity may decrease. The conductivity of the rolled copper foil is preferably 50% IACS or more, more preferably 60% IACS or more, and still more preferably 80% IACS or more. Moreover, although copper foil thickness is not specifically limited, Preferably it is 5-50 micrometers, More preferably, it is 5-35 micrometers.

The rolled copper foil of the present invention has a 60-degree glossiness G in the rolling parallel direction of more than 500. For this reason, the smoothness of the copper foil surface becomes good, and the transparency of the resin after removing the copper foil by etching becomes good even if a roughening treatment for obtaining good adhesion with the resin is performed. When the 60-degree glossiness G in the rolling parallel direction is 500 or less, when the roughening treatment is performed to obtain good adhesion to the resin, the transparency of the resin after removing the copper foil by etching is good. It becomes difficult to obtain.
Further, the 60-degree glossiness G in the rolling parallel direction is preferably 520 or more, and more preferably 550 or more. It is even more preferable that the 60 degree glossiness G in the rolling parallel direction is 600 or more. Although there is no upper limit on the 60-degree glossiness G in terms of the characteristics of the copper foil, the 60-degree glossiness G in the rolling parallel direction can be set to 900 or less in consideration of manufacturability and the like.

  The rolled copper foil of the present invention performs 180 ° adhesion bending with a polyimide film surface on the inside of a sample of a single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less obtained by laminating a copper foil and a polyimide film having a film thickness of 25 μm. The number of times of bending until the copper foil breaks is preferably 3 times or more, and more preferably 5 times or more. If the flexibility is good so as to satisfy such conditions, it can be suitably used as an LCD module FPC.

As a manufacturing method of the rolled copper foil of this invention, a raw material is first melt | dissolved in a melting furnace and the molten metal of a desired composition is obtained. Then, this molten metal is cast into an ingot. Thereafter, hot rolling, cold rolling, and annealing are appropriately performed to finish a foil having a predetermined thickness. After the heat treatment, surface pickling, polishing, or the like may be performed in order to remove the surface oxide film generated during the heat treatment. In the final cold rolling, the material after the heat treatment is repeatedly passed through a rolling mill to be finished to a predetermined thickness. In the method for producing rolled copper foil of the present invention, the oil film equivalent in the final rolling pass of the final cold rolling step is 17000 or less, the oil film equivalent in the rolling pass immediately before the final rolling pass is 15000 or less, and the oil film in the rolling pass immediately before that It is important to perform the final rolling pass after adjusting the equivalent rolling to 10000 or less and adjusting the 60 degree gloss in the rolling parallel direction to be greater than 500 immediately before the final rolling pass in the final rolling step.
Here, the oil film equivalent is defined by the following equation.
Oil film equivalent = {(rolling oil viscosity [cSt]) × (sheet feeding speed [mpm] + roll peripheral speed [mpm])} / {(roll biting angle [rad]) × (yield stress of material [kg / mm ² ])}
The rolling oil viscosity [cSt] is a kinematic 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 sheet passing speed may be used.
By controlling the oil film equivalent, deformation of the material surface is constrained by the roll, and an increase in surface roughness accompanying a change in thickness due to rolling can be suppressed. Further, by increasing the gloss level immediately before the final rolling pass, the gloss level after the final pass can be controlled within a desired range. If the gloss level is low immediately before the final pass, even if the material surface is smoothed in the final pass, deep irregularities formed up to the previous pass remain, and the desired surface shape cannot be obtained.

  In addition, when the oil film equivalent is small, the unevenness on the surface of the rolling roll used for rolling is easily transferred to the material surface, and therefore the surface of the rolling roll is preferably smooth. For this reason, it is preferable that the average roughness Ra when the rolling roll used with the manufacturing method of the rolled copper foil of this invention is measured in the direction parallel to the rotating shaft of a roll is 0.1 micrometer or less.

  The rolled copper foil of the present invention can be bonded to a resin substrate from the roughened surface side to produce a laminate. The resin substrate is not particularly limited as long as it has characteristics applicable to a printed wiring board and the like. For example, a polyester film such as polyethylene terephthalate (PET), a polyimide film, a liquid crystal polymer (LCP) film, etc. are used. I can do it.

  The method of laminating can be applied to a substrate such as a polyimide film via an adhesive, or laminated and bonded to a rolled copper foil under high temperature and high pressure without using an adhesive, or a polyimide precursor is applied and dried. -A laminated board can be manufactured by performing hardening etc.

As Examples 1 to 11 and Comparative Examples 1 to 5, each rolled copper foil was prepared as follows.
First, after producing a copper ingot having the composition shown in Table 1 and performing hot rolling, cold rolling and annealing in an annealing furnace set at a temperature of 300 to 800 ° C. are repeated one or more times, and then cold rolling is performed. Thus, a rolled plate having a thickness of 1 to 2 mm was obtained. The rolled sheet was annealed and recrystallized in an annealing furnace set to a temperature of 300 to 800 ° C., and finally cold-rolled to the thickness shown in Table 1. At this time, in Examples 1 to 11, in the final cold rolling step, the oil film equivalent was 17000 or less in the final rolling pass, the oil film equivalent in the rolling pass immediately before the final rolling pass was 15000 or less, and the oil film in the rolling pass immediately before that. The rolling conditions were adjusted so that the equivalent was 10,000 or less, and the rolling conditions were adjusted so that the 60-degree glossiness in the rolling parallel direction was the value shown in Table 1 immediately before the final rolling pass. In Table 1, an oil film equivalent in the final rolling pass is “final pass oil film equivalent”, an oil film equivalent in the rolling pass immediately before the final rolling pass is “oil film equivalent in the last one pass”, and an oil film equivalent in the rolling pass immediately before is “ The final two-pass pre-oil film equivalent ”.
For Comparative Examples 1 to 5, final cold rolling was performed under the conditions described in Table 1.
Moreover, the average roughness Ra when the rolling roll used at this time measured in the direction parallel to the rotating shaft of a roll was 0.08 micrometer.

The conditions for the roughening treatment were set as follows. The conditions for the roughening treatment were generally used for FPC applications as those that would give practically sufficient peel strength.
-Plating bath composition: Cu 15 g / L, Co 8.5 g / L, Ni 8.6 g / L
-Treatment solution pH: 2.5
・ Processing temperature: 38 ℃
・ Current density: 20 A / dm ²
・ Plating time: 2.0 seconds

Various evaluation was performed as follows about each sample of the Example and comparative example which were produced as mentioned above.
・ Glossiness;
Using a gloss meter Handy Gloss Meter PG-1 manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS Z8741, the glossiness of the copper foil before the surface treatment was determined at an incident angle of 60 degrees in the rolling direction.

・ Visibility (resin transparency);
Evaluation of resin transparency was performed using haze values. Here, the haze value (%) is a value calculated by (diffuse transmittance) / (total light transmittance) × 100.
One surface of each sample copper foil was plated under the following conditions as a roughening treatment.
-Plating bath composition: Cu 15 g / L, Co 8.5 g / L, Ni 8.6 g / L
-Treatment solution pH: 2.5
・ Processing temperature: 38 ℃
・ Current density: 20 A / dm ²
-Plating time: 2.0 seconds Next, about the roughened copper foil, the roughened surface side was bonded to both surfaces of the polyimide film with a thermosetting adhesive for lamination (thickness 50 μm, Ube Industries Upilex), and the copper foil Was removed by etching (ferric chloride aqueous solution) to prepare a sample film. A haze value of a sample film was measured using a haze meter HM-150 manufactured by Murakami Color Research Laboratory based on JIS K7136 (2000).

・ Peel strength (adhesive strength);
In accordance with PC-TM-650, the normal peel strength is measured with a tensile tester Autograph 100, and the normal peel strength is 0.7 N / mm or more that can be used for laminated substrate applications (determination “◯”). Those with less than 0.7 N / mm could not be used (judgment “x”).

・ Bendability;
When a sample of a single-sided copper-clad laminate with a width of 3 mm or more and 5 mm or less, in which each copper foil and a polyimide film with a film thickness of 25 μm were laminated, was subjected to 180 ° adhesion bending with the polyimide film surface inside, the copper foil The number of bendings until the fracture occurred was measured.
Table 1 shows the conditions and evaluation of each test.

(Evaluation results)
The SEM image of the copper foil surface of Example 2 is shown in FIG. FIG. 2 shows an SEM image of the copper foil surface of Comparative Example 2.
In each of Examples 1 to 11, the 60-degree glossiness G in the rolling parallel direction was greater than 500, and the adhesion to the resin, the visibility of the resin, and the bendability were good.
In each of Comparative Examples 1 to 5, the 60-degree glossiness G in the rolling parallel direction was 500 or less, and the visibility of the resin was poor. Some also had poor bendability.

Claims (7)

It is a rolled copper foil whose 60 degree glossiness G in the rolling parallel direction is greater than 500,
When a single-sided copper clad laminate having a width of 3 mm or more and 5 mm or less obtained by laminating the copper foil and a polyimide film having a film thickness of 25 μm was subjected to 180 ° adhesion bending with the polyimide film surface inside, the copper A rolled copper foil in which the number of bending times until the foil breaks is 3 or more.   The rolled copper foil according to claim 1, wherein the 60-degree glossiness G in the rolling parallel direction is 600 or more.   The rolled copper foil according to claim 1 or 2, wherein the 60-degree glossiness G in the rolling parallel direction is 900 or less.   The rolled copper foil according to any one of claims 1 to 3, wherein the number of times of bending until the copper foil breaks is 5 or more.   The oil film equivalent in the final rolling pass of the final cold rolling step is 17000 or less, the oil film equivalent in the rolling pass immediately before the final rolling pass is 15000 or less, and the oil film equivalent in the immediately preceding rolling pass is 10,000 or less, and the final rolling step 5. The method for producing a rolled copper foil according to claim 1, wherein the final rolling pass is performed after adjusting so that the 60 ° gloss in the rolling parallel direction is greater than 500 immediately before the final rolling pass. .   The manufacturing method of the rolled copper foil of Claim 5 which performs rolling using the rolling roll whose average roughness Ra when measured to the direction parallel to the rotating shaft of a roll is 0.1 micrometer or less.   The laminated board comprised by laminating | stacking the rolled copper foil and resin substrate in any one of Claims 1-4.