JP2006283078A - Rolled copper foil for copper-clad laminate, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolled copper foil for a copper-clad laminate, which gives superior transparency to a resin after the foil has been etched and removed, has practical flexibility and has adhesion strength to a resin. <P>SOLUTION: The rolled copper foil has such I<SB>(100)[001]</SB>and I<SB>(110)[1-12]</SB>which are strength ratios of (100)[001] and (110)[1-12] to a copper powder sample in a figure of a pole (111) measured on a final-rolled sheet as to satisfy the following conditions: I<SB>(110)[1-12]</SB>≥5 and 2≥I<SB>(100)[001]</SB>/I<SB>(110)[1-12]</SB>≥0.3; has a glossiness of 300 or higher on a final-rolled sheet; has a thickness preferably of 5 to 20 μm; and has a electroconductivity preferably of 80% IACS or higher. The method for manufacturing the rolled copper foil comprises the steps of: annealing a copper foil before final rolling to control I<SB>(100)[001]</SB>/I<SB>0(100)[001]</SB>into 5 or more but less than 35; and then cold-rolling it at a reduction rate of 85% or more but less than 93%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rolled copper foil for a copper clad laminate and a method for producing the same. More specifically, the present invention relates to a rolled copper foil for a copper clad laminate suitable for a field where transparency of a resin remaining after etching the copper foil of a copper clad laminate is required, and a method for producing the same. In addition, resin here means what is used for copper clad laminated boards, such as a polyimide resin and a liquid crystal polymer.

In recent years, a method using a mounting film carrier tape has been adopted as a mounting method for small electronic components, and a COF (chip that directly mounts an IC chip on a film carrier tape as a method for mounting at a higher density, among others.・ On-film method has been put into practical use. The film carrier tape for COF uses a laminated film in which a conductor (copper foil) and a resin insulating layer are laminated in advance, and the positioning pattern required for direct mounting on the wiring pattern of the IC chip is formed on the conductor side. The Therefore, the positioning at the time of mounting the IC chip is performed through a positioning pattern that is visible through the resin insulating layer remaining after etching the copper foil of the copper clad laminate. For this reason, the transparency of the resin is important in the film carrier tape used for COF.
In this case, when a copper foil having a large surface roughness is used, the surface of the resin insulating layer remaining after etching the copper foil becomes rough, which causes a poor transparency. Therefore, as a copper-clad laminate that is easy to align, a laminate (film) is used in which Ni or the like is sputtered on a polyimide film or the like and then copper-plated. However, the adhesive strength is low and the (ion) migration resistance is poor. There was a problem. Ion migration is a phenomenon in which a circuit is short-circuited by repeating dissolution, migration, and precipitation when a voltage is applied to a conductor metal with moisture attached.

Moreover, a copper clad laminated board can also be manufactured even if it uses the rolled copper foil by which the rough plating was given to the surface. This rolled copper foil usually uses tough pitch copper (oxygen content of 100 to 500 ppm by weight) or oxygen free copper (oxygen content of 10 ppm by weight or less) as a raw material, and after hot rolling these ingots, It is manufactured by repeating cold rolling and annealing to a thickness. Patent Document 1 proposes a low roughness electrolytic foil having a high surface gloss.
On the other hand, Patent Document 2 proposes a rolled copper foil having an oil pit depth of 2.0 μm or less on the surface formed by a cold rolling process under conditions such as oil film control as a copper foil having excellent flexibility. ing.
Furthermore, Patent Document 3 describes a rolled copper foil in which a cubic texture is remarkably developed after recrystallization annealing for the purpose of imparting high flexibility, but for flexible printed circuit board (FPC) flexible wiring member applications. A cubic texture developed by recrystallization annealing after the final cold rolling is obtained.

JP 2004-98659 A JP 2001-58203 A JP 2001-323354 A

In Patent Document 1, a low-roughness copper foil obtained by improving adhesion with an organic treatment agent after blackening treatment or plating treatment is broken due to fatigue in applications where flexibility is required for a copper-clad laminate. There are things to do. Further, even if a rolled copper foil having an oil pit state as described in Patent Document 2 is used, the transparency of the resin cannot be obtained.
Further, the rolled copper foil of Patent Document 3 has a final rolling workability of 93% or more in order to obtain a high cube texture, and oil pits are generated due to shear band deformation in the final rolling. I can't get it. Furthermore, the recrystallized foil of Patent Document 3 has a large unevenness on the etching surface corresponding to crystal grains, and is not suitable for use in a copper clad laminate for COF that requires fine pitch compatibility.
The present invention provides a rolled copper foil for a copper-clad laminate that is excellent in resin transparency after removing the rolled copper foil by etching and has practical flexibility and adhesive strength between the resin.

The present invention relates to the strength ratios I _{(100) [001]} and I _{(110) [ 100} ] [001] and (110) [1-12] to the copper powder sample in the (111) pole figure measured after the final rolling. _1-12] relates to a rolled copper foil that satisfies the following conditions and has a glossiness of 300 or more after final rolling.
I _{(110) [1-12]} ≧ 5; and 2 ≧ I _{(100) [001]} / I _{(110) [1-12]} ≧ 0.3
The rolled copper foil may have a thickness of 5 to 20 μm.
The rolled copper foil may have a conductivity of 80% IACS or higher.
In the present invention, I _{(100) [001]} / I _{0 (100) [001] is set} to 5 or more and less than 35 in the annealing before final rolling, and then cold rolled at a working degree of 85% or more and less than 93%. It is related with the manufacturing method of the rolled copper foil of description.

  According to the present invention, the rolled copper foil is etched without requiring a costly rolling process such as rolling at a low speed with less oil lubrication (oil film is thin) or rolling using a roll with very fine roughness. It has become possible to provide a rolled copper foil for copper-clad laminates that is excellent in resin transparency after being removed in step 1 and is practical in terms of flexibility and adhesive strength with the resin.

In the rolled copper foil of the present invention, (100) [001] and (110) [1-12] (“-1” in parentheses in the parenthesis indicate a horizontal bar on the (111) pole figure measured after the final rolling. The strength ratio I _{(110) [1-12]} of the copper powder sample is I _{(110) [1-12]} ≧ 5, preferably I _{(110) [1-12]} ≧ 7, More preferably, I _{(110) [1-12]} ≧ 10. If the intensity ratio I _{(110) [1-12]} is less than 5, the foil is in a state where the cube orientation has developed too much. This is, for example, a recrystallized state, the strength is lowered, and lamination with the resin becomes difficult. Note that I _{(110) [1-12]} exceeding 15 cannot be an industrial level rolling method.
Further, the intensity ratios I _{(100) [001]} and I _{(110) [1-12]} are 2 ≧ I _{(100) [001]} / I _{(110) [1-12]} ≧ 0.3, preferably 2 ≧ I _{(100) [001]} / I _{(110) [1-12]} ≧ 0.35, more preferably 1.5 ≧ I _{(100) [001]} / I _{(110) [1-12]} ≧ 0. Satisfies 35 relationships. If the strength ratio exceeds 2, the foil is in a state where the cube orientation has developed too much. This is, for example, a recrystallized state, the strength is lowered, and lamination with the resin becomes difficult. On the other hand, if it is less than 0.3, glossiness cannot be obtained.

In addition, how to obtain (100) [001] and (110) [1-12] in the (111) pole figure is as follows.
Α in the range of −15 degrees to −90 degrees with an X-ray diffractometer (XRD) was measured at a measurement interval of 5 degrees, and a (111) pole figure was obtained by the Schulz reflection method. FIG. 1 shows an example of the angle α in the (111) pole figure. “I _{α = −45} ” is an average intensity of four peaks appearing when the copper foil sample is rotated in-plane at α = −45 degrees, and “I _{0, α = −45} ” is copper powder at α = −45 degrees. The average intensity that appears when the sample is rotated in-plane, “I _{α = −65} ” is the average intensity of four peaks that appear when the copper foil sample is rotated in-plane at α = −65 degrees, “I _{0, α = When} “ ₋₆₅ ” is defined as an average strength appearing when the copper powder sample is rotated in-plane at α = −65 degrees, the following equation is established.
I _{(100) [001]} / I _{(110) [1-12]} = ( _{Iα = −45} / I0 _{, α = −45} ) / ( _{Iα = −65} / I0 _{, α = −65} )

  In addition, the glossiness was measured using a glossmeter based on JIS Z8741 at an incident angle of 60 degrees perpendicular to the rolling direction. The gloss after the final rolling of the rolled copper foil of the present invention is 300 to 500, preferably 350 or more, more preferably 370 or more. When it is less than 300, when used for a film carrier tape for COF, the visibility of the positioning pattern at the time of mounting the IC chip is deteriorated, and accurate positioning becomes difficult. On the other hand, if it exceeds 500, since the surface is too smooth, the transportability in the process of laminating the foil with the resin deteriorates. The glossiness of the nickel-plated and chromate-treated glossy finish copper foil usually used for the COF copper-clad laminate is 350 (haze value 25%).

The thickness of the rolled copper foil of the present invention can be measured by, for example, the gravimetric method according to IPC-TM-650. However, the yield in the manufacturing process becomes very poor. On the other hand, if the thickness exceeds 20 μm, the distortion generated on the outer periphery of the bent portion at the time of bending increases, so that the flexibility is lowered.
The conductivity of the rolled copper foil of the present invention can be determined, for example, by measuring and calculating the electrical resistance according to IPC-TM-650, preferably 80% IACS or more, more preferably 85% IACS or more, Most preferably, it is 90% IACS or more. If it is less than 80% IACS, it is not suitable for a copper foil for a copper clad laminate for COF.

A rolled copper foil for a copper clad laminate is generally processed at high speed by oil lubrication. Moreover, since the required thickness is thin, the workability (sheet thickness reduction rate) of the final rolling becomes essentially large. Here, the workability d in cold rolling is given by d = (t ₀ −t) / t ₀ × 100 (%) (where t ₀ and t are thicknesses before and after each cold rolling). . Therefore, the rolling process of the copper foil for copper clad laminates is a process in a region that can be deformed only by shear band deformation. This shear band usually causes a depression called an oil pit on the rolled surface. The oil pit is usually shallower as the crystal grain size of the material is smaller. When the intensity ratios I _{(100) [001]} and I _{(110) [1-12]} have a specific relationship, the frequency and depth are the smallest.
For controlling the generation of the oil pits, it is effective to adjust rolling conditions such as material surface condition, rolling roll diameter, rolling roll surface roughness, rolling reduction, rolling speed, rolling oil viscosity, etc. The element is the structure before final rolling. Based on this knowledge, the present invention suppresses the formation of oil pits to increase the gloss of the rolled copper foil surface, and as a result, improves the transparency of the resin from which the rolled copper foil of the copper clad laminate has been removed by etching. We were able to.

  In addition, as a raw material of the copper foil of the present invention, a copper alloy that contains a large amount of alloy elements and does not soften unless annealed at a high temperature is not suitable as a raw material. On the other hand, it is necessary to prevent softening during normal temperature storage and to lower the softening temperature. Therefore, an alloy material in which the softening temperature is adjusted to an appropriate range by adding a small amount of Ag or Sn or the like to tough pitch copper and / or oxygen-free copper, which is copper whose recrystallized texture is in a cubic orientation. . This is because even if alloy elements are contained, the development of the cubic texture is not hindered if the concentration range is very small (about 0.03 to 0.15% by weight).

In the method for producing a rolled copper foil of the present invention, the texture component obtained by annealing before the final rolling is in a cubic orientation, so that the development of shear bands in the final rolling can be suppressed and the formation of oil pits can be suppressed. The mechanism that suppresses the development of the shear band by increasing the cubic shape is not clear, but the crystal orientation anisotropy of the deformation resistance and the crystal orientation anisotropy of the angle between the slip surface and the shear band are affected. The result is estimated.
The texture component necessary after annealing before final rolling is such that I _{(100) [001]} / I _{0 (100) [001]} is 5 or more and less than 35, preferably more than 10 and less than 35. If I _{(100) [001]} / I _{0 (100) [001]} is less than 5, the glossiness required after rolling cannot be obtained. On the other hand, if it is 35 or more, constriction occurs during rolling, and pinholes occur frequently. In order to set I _{(100) [001]} / I _{0 (100) [001]} within a predetermined range, a person _{skilled in the art} will determine the heating temperature / speed, annealing temperature / speed, time, etc. according to the annealing equipment, scale, and materials used. Can be adjusted as appropriate by changing the crystal grain size, for example, by melting and casting the cake, hot rolling, cold rolling (1), intermediate annealing, cold rolling (2), final It is obtained by processing in the order of annealing and finish (final) rolling.
The final rolling is cold rolling at a working degree of 85% or more and less than 93%, preferably 88% to 92%. When the degree of processing is 93% or more, a shear band develops and an oil pit is generated. On the other hand, if it is less than 85%, a required amount of cubic structure cannot be obtained.

As described above, the development of shear bands in the final rolling can be suppressed and the formation of oil pits can be suppressed by setting the texture component to a high cube orientation by annealing before the final rolling. For example, as a substitute value of the maximum depth of the oil pit of the rolled copper foil of the present invention, when expressed as the maximum height (Ry) according to the surface roughness JIS B0601, it is usually 0.2 to 1.0 μm, preferably The thickness was 0.2 to 0.8 μm, more preferably 0.2 to 0.5 μm.
Furthermore, the number of pinholes of the copper foil of the present invention can be measured by the number of holes that transmit light that can be observed when the copper foil is placed on a light table. The number of pinholes increases exponentially as the foil thickness decreases. Usually, if it is 18 micrometers foil, it is 15 or less / 1000m, Preferably it is 10 or less / 1000m, More preferably, it is 5 or less / 1000m.
The pit generated by the oil pit may act as a crack starting point when the copper foil is repeatedly bent and deformed because the shape of the tip of the pit is acute. Therefore, the rolled copper foil of the present invention in which the formation of oil pits is suppressed is also excellent in bending resistance.

Embodiments of the present invention will be described below with reference to examples. Various evaluations were performed as follows.
(1) (100) [001] and (110) [1-12] in the (111) pole figure by X-ray diffractometer (XRD);
XRD tube: Co (30 kV, 100 mA), α in the range of −15 degrees to −90 degrees was measured at a measurement interval of 5 degrees, and a (111) pole figure was obtained by the Schulz reflection method. The copper powder sample manufactured by the atomizing method was used.
(2) Glossiness;
Using a gloss meter (trade name “PG-1M”, manufactured by Nippon Denshoku Industries Co., Ltd.) conforming to JIS Z8741, the gloss was measured at an incident angle of 60 degrees perpendicular to the rolling direction.
(3) Visibility (resin transparency);
Electrolytic chromate treatment is applied to the copper foil surface, and polyimide varnish (trade name “U Varnish-A”, manufactured by Ube Industries Co., Ltd.) is applied to a thickness of 40 μm (temperature is the recommended temperature profile described in the product catalog) The sample film was prepared by removing the front surface of the copper foil with an aqueous ferric chloride solution.
A binary image of a demonstration alignment mark obtained by transmitting through a sample film was observed using an image analysis apparatus capable of binarizing a CCD image with 256 gradations. A film having a binarized image similar to the film that passed the mounting test in advance was evaluated as “◯” (passed), and a film in which the outline of the mark was broken was evaluated as “×” (failed).

(4) Thickness;
It measured based on IPC-TM-650 by the gravimetric method.
(5) Conductivity;
The electrical resistance was measured according to IPC-TM-650, and% IACS was calculated from the obtained specific resistance ρ (μΩ · cm) by the following formula.
% IACS = 1.7241 × 10 ² / ρ
(6) Copper foil strength (adhesion strength = peel strength);
Based on PC-TM-650, the normal peel strength was measured with a tensile tester Autograph 100 and the peel strength measured in a normal state after exposure in an oven at 150 ° C. for 1 week, and the normal peel strength was 0.7 N. When the peel strength maintenance rate after exposure at 150 ° C is 80% or more at ≥ / mm, it can be used for copper-clad laminate applications, and the normal peel is less than 0.7 N / mm or maintained after exposure at 150 ° C The case where the rate was less than 80% was evaluated as “x” as inappropriate.
(7) Pinhole measurement;
The number of pinholes in a × 20 m copper foil was measured.
(8) Measurement of oil pit depth substitute value;
As a substitute value for the depth (maximum value) of the oil pit, a contact roughness meter (manufactured by Kosaka Laboratory, trade name “SE-3400”) was used to measure the maximum height (Ry) in accordance with JIS B0601. . The measurement position is changed 10 times in parallel with the rolling direction under the conditions of a measurement standard length of 0.8 mm, an evaluation length of 4 mm, a cut-off value of 0.8 mm, and a feed rate of 0.1 mm / second. The maximum value of was obtained. This Ry value corresponds to the maximum depth of the oil pit.
(9) Flexibility;
The bending fatigue life was measured. The used apparatus has a structure in which a vibration transmission member is coupled to an oscillation driver, and the copper foil to be tested is fixed to the apparatus at a total of four points, that is, a screw portion and a tip portion of the vibration transmission member. When the vibration transmitting member is driven up and down, the intermediate portion of the copper foil is bent into a hairpin shape with a predetermined radius of curvature r. The number of times to break when bending was repeated under the following conditions was determined.
Ni plating with a thickness of about 50 nm is applied to one side of the copper foil, and U varnish A manufactured by Ube Industries Co., Ltd. is coated with a thickness of 40 μm by the casting method after the chromate treatment. Specimen sampling direction: Specimen length direction was parallel to the rolling direction, radius of curvature r: 2.5 mm, vibration stroke: 25 mm, vibration speed: 1500 times / min. . The time point when the electrical resistance increased by 10% was taken as the end point of the test, and the case where the number of flexing times was 10 ⁵ or more was designated as “◯”, and the value less than 10 ⁵ was designated as “X”.

Examples 1-3, Comparative Examples 1-3
A cake containing Sn at 950 ppm and having components other than Sn and Cu satisfying oxygen-free copper C1020 (oxygen content less than 10 ppm) is melt cast, hot rolling, cold rolling (1), intermediate annealing, cold rolling ( 2) Processed in the order of final annealing and finish (final) rolling to obtain a foil having a thickness of 18 μm. Intermediate annealing and final annealing were continuously recrystallized by continuous annealing. Finish rolling was performed at a speed of 400 mpm or more with a roll having a roll surface Ra of 0.05 to 0.15 μm. The rolled copper foils of Examples and Comparative Examples shown in Table 1 were obtained by changing the final rolling work degree such as the presence / absence of intermediate annealing and the time / temperature of intermediate annealing. In addition, the comparative example 1 recrystallizes and anneals Example 2. This recrystallization annealing was performed by heating the sample at a temperature 70 ° C. higher than the semi-softening temperature for 30 minutes. Here, the semi-softening temperature is an annealing temperature when the tensile strength after annealing becomes an intermediate value between the tensile strength of the material after rolling and the tensile strength of the material after complete softening. The temperature was first measured for 30 minutes.
Table 1 shows the results. The conductivity measured after the final rolling of the rolled copper foil of Example 1 was 90.2%. Although not shown in Table 1, it was manufactured under the same conditions as in Example 1 and before finishing (final) rolling, with the thickness changed to 12 μm and 9 μm. As a result, there were no problems with glossiness, visibility, conductivity, and strength. In addition, in the copper alloy of this composition (containing Sn950 ppm), no problem of occurrence of pinholes was observed even when the content exceeded 93%. The substitute value Ry of the oil pit depth on the copper foil surface of Example 1 was 0.25 μm. On the other hand, the substitute value Ry of the oil pit depth of Comparative Example 2 was 1.3 μm.
In Comparative Example 1, Example 2 was recrystallized and annealed. Since I _{(100) [001]} / I _{(110) [1-12]} is large, the copper foil strength is low. In Comparative Example 2, since I _{(100) [001]} / I _{0 (100) [001]} before final rolling is less than 5, a necessary amount of highly cubic structure after rolling cannot be obtained, and glossiness and visibility are low. It was bad. In Comparative Example 3, since the final degree of processing was less than 85%, the required amount of cubic structure was not obtained after rolling, and the glossiness and visibility were poor.

Examples 4-6, Comparative Examples 4-7
A cake containing 1000 ppm of Ag and containing oxygen-free copper C1020 with components other than Ag and Cu melt-cast, hot rolled, cold rolled (1), intermediate annealed, cold rolled (2), final annealed, finished The foil was processed in the order of rolling to obtain a foil having a thickness of 18 μm. The presence or absence of intermediate annealing, the time / temperature of intermediate annealing, etc. were changed to obtain rolled copper foils of Examples and Comparative Examples shown in Table 1.
Table 1 shows the results. The conductivity measured after the final rolling of the rolled copper foil of Example 4 was 95.2%. Comparative Example 6 and Comparative Example 7 were manufactured under the same conditions as in Example 4 and before finishing (final) rolling, with the thickness changed to 12 μm and 9 μm.
In Comparative Example 4, the required amount of cubic structure was not obtained after rolling due to the relationship between the Ag content and the workability of the final rolling, and the glossiness and visibility were poor. In Comparative Example 5, since I _{(100) [001]} / I _{0 (100) [001]} before final rolling is less than 5, the required amount of cubic structure cannot be obtained after rolling, and glossiness and visibility are poor. Met. In Comparative Example 6, there were no problems with glossiness, visibility, conductivity, and strength, but I _{(100) [001]} / I0 _{(100) [001]} before final rolling was 35 or more, so during final rolling Constriction occurred frequently and it became a pinhole. In Comparative Example 7, there were no problems with glossiness, visibility, conductivity, and strength, but since the final degree of processing was 93% or more, shear bands occurred frequently, which became pinholes. When the thickness was 12 μm or less, the number of pinholes increased and it was not suitable for copper clad laminate use.

Comparative Examples 8-9
Melting and casting a cake containing 2000 ppm of Sn and components other than Sn and Cu satisfying oxygen-free copper C1020, hot rolling, cold rolling (1), intermediate annealing, cold rolling (2), final annealing, finishing The foil was processed in the order of rolling to obtain a foil having a thickness of 18 μm. The presence or absence of intermediate annealing, the time and temperature of intermediate annealing, etc. were changed, and the rolled copper foil of the comparative example shown in Table 3 was obtained.
Table 1 shows the results. Since the comparative example 8 had much Sn content, the electrical conductivity of the rolled copper foil after final rolling was 78.5%, and was not suitable for a copper clad laminated board use. In Comparative Example 9, in addition to low electrical conductivity, the inclusion of a large amount of Sn urged the reduction of I _{(100) [001]} in rolling, so the required amount of highly cubic structure was not obtained after rolling. , Glossiness and visibility were poor.

It is an illustration of angle (alpha) in a (111) pole figure.

Claims (4)

Strength ratios I _{(100) [001]} and I _{(110) [1-12]} of copper powder samples of (100) [001] and (110) [1-12] in the (111) pole figure measured after the final rolling However, the rolled copper foil for copper clad laminated boards which satisfy | fills the following conditions and the glossiness after final rolling is 300 or more.
I _{(110) [1-12]} ≧ 5; and 2 ≧ I _{(100) [001]} / I _{(110) [1-12]} ≧ 0.3   The rolled copper foil according to claim 1, wherein the thickness is 5 to 20 μm.   The rolled copper foil according to claim 1 or 2, wherein the electrical conductivity is 80% IACS or more. The I _{(100) [001]} / I _{0 (100) [001]} is made 5 or more and less than 35 in the annealing before the final rolling, and then cold rolled at a working degree of 85% or more and less than 93%. The manufacturing method of the rolled copper foil for copper clad laminated boards of any one of these.

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