JP5753115B2 - Rolled copper foil for printed wiring boards - Google Patents

Description

  The present invention relates to a rolled copper foil for printed wiring boards, and more particularly to a rolled copper foil suitable as a conductive material for FPC (Flexible Printed Circuit).

  Printed wiring board (PWB) refers to the surface of an electrically insulating material (insulating substrate) (in some cases, also inside), with a conductive pattern formed and secured with a conductive material. A printed circuit board (PCB) that has been mounted and soldered has been completed. The printed circuit board is an indispensable part for controlling various electronic devices.

  In general, a copper-clad laminate is used as a base material for a printed wiring board. A copper-clad laminate is manufactured by laminating and bonding a copper foil to an insulating substrate such as a synthetic resin board or a film via an adhesive or without using an adhesive under high temperature and pressure.

  Of the printed wiring boards, FPC (Flexible Printed Circuit), which is frequently used for wiring of movable parts and bent parts, requires excellent bending fatigue characteristics, so rolled copper with superior bending characteristics compared to electrolytic copper foil. Efforts have been made to improve the bending characteristics, centering on foil. For example, in Japanese Patent Application Laid-Open No. 2001-323354 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2008-248331 (Patent Document 2), by developing a cube texture ((100) [001] orientation), bending characteristics are improved. We are trying to improve.

  In Japanese Patent Application Laid-Open No. 2009-158382 (Patent Document 3), the slope B at the linear portion near the origin in the stress-strain curve of the copper foil measured before the heat treatment at 300 ° C. The ratio B / A with respect to the slope A in the linear portion near the origin in the stress-strain curve of the copper foil measured in the state after the heat treatment at ℃ was from 1.2 to 3.0 It is disclosed to control.

  In JP 2012-001786 A (Patent Document 4), the Young's modulus in the 0 degree direction (degree is the angle formed with the length direction of the copper foil, the same applies hereinafter) is 80 to 150 GPa, and heat treatment at 360 ° C. for 6 minutes. Proposed a copper foil having a Young's modulus in the 0 degree and 90 degree directions of 25 to 80 GPa after the heat treatment and a Young's modulus in the 45 degree direction of 80 to 150 GPa after the heat treatment to improve the bending fatigue properties after the heat treatment. In addition, the copper foil is prevented from being bent by the line tension before the heat treatment.

JP 2001-323354 A JP 2008-248331 A JP 2009-158382 A JP 2012-001786 A

  In the manufacturing process of the copper clad laminate, heat treatment is performed to bond the copper foil to the insulating substrate, and the copper foil is generally recrystallized by this heat treatment. In an industrial production line for copper-clad laminates, the copper foil is laminated with an insulating substrate while tension is applied. However, the physical properties of the copper foil differ before and after recrystallization. There was a problem that wrinkles were likely to occur near the boundary with the structure and at the part after recrystallization. The rolled copper foil described in Patent Document 4 also aims to suppress the occurrence of folds when tension is applied before the heat treatment, but it is a countermeasure in terms of suppressing wrinkles due to physical property differences before and after the heat treatment. However, there is still room for improvement.

  Then, the subject of this invention makes it a subject to provide the rolled copper foil which is hard to generate | occur | produce a wrinkle due to the physical property difference before and behind heat processing in the production line of a copper clad laminated board. Moreover, the further subject of this invention is providing the copper clad laminated board provided with such a rolled copper foil.

  As a result of intensive studies to solve the above problems, the present inventor has found that wrinkles can be significantly suppressed by controlling the difference ΔE in Young's modulus before and after recrystallization of the rolled copper foil.

  The present invention has been completed based on the above findings. In one aspect, the Young's modulus E1 in the rolling direction at 25 ° C. is E1 = 80 to 130 GPa, and after heat treatment at 350 ° C. for 1 second, 25 ° C. The rolled copper foil for printed wiring boards has a Young's modulus E2 in the rolling direction of E2 = 60 to 110 GPa and a difference ΔE = E1−E2 between the Young's modulus E1 and Young's modulus E2 of 12 to 33 GPa.

In one embodiment of the rolled copper foil for a printed wiring board of the present invention, the 200 diffraction intensity (I) obtained by X-ray diffraction of the rolled surface after heat treatment at 350 ° C. for 1 second is a fine powdered copper. For the 200 diffraction intensity (I ₀ ) determined by X-ray diffraction, 10 ≦ I / I ₀ ≦ 30.

  In another embodiment of the rolled copper foil for printed wiring boards of the present invention, the Young's modulus E1 in the rolling direction at 25 ° C. is E1 = 85 to 125 GPa, and after heat treatment at 350 ° C. for 1 second, 25 The Young's modulus E2 in the rolling direction at ° C. is E2 = 65 to 100 GPa.

  In another embodiment of the rolled copper foil for printed wiring boards of this invention, (DELTA) E is 15-30 GPa.

  In another aspect, the present invention is a copper-clad laminate including the rolled copper foil for a printed wiring board.

  In yet another aspect, the present invention is a printed wiring board made of the copper clad laminate.

  By producing a copper-clad laminate using the rolled copper foil according to the present invention, the generation of wrinkles associated with the heat treatment is suppressed, so that improvement in productivity and yield can be expected.

It is the schematic of the testing apparatus used when evaluating a bending fatigue characteristic.

(1. Composition of copper foil)
The copper foil base material used in the present invention is a rolled copper foil. Rolled copper foil is superior to electrolytic copper foil in that it can cope with an environment in which vibration continuously occurs and has high bending resistance. In the present invention, “copper foil” includes copper alloy foil. There is no restriction | limiting in particular as a material of copper foil, What is necessary is just to select suitably according to a use or a required characteristic. The Cu concentration in the copper foil is preferably 99.8% by mass or more, more preferably 99.85% by mass or more, and more preferably 99.9% by mass or more for reasons of ensuring high conductivity. Is more preferable. However, even if the Cu concentration is too high, it leads to an increase in cost, so 99.999% by mass or less is preferable, and 99.995% by mass or less is more preferable. The oxygen concentration in the copper foil leads to an increase in cuprous oxide, which leads to the generation of pinholes due to cuprous oxide, preferably 0.05 mass or less, more preferably 0.01 mass% or less, More preferably, it is 0.005 mass% or less, for example, can be 0.0001 mass% or more and 0.01 mass% or less. For example, oxygen-free copper or tough pitch copper defined in JIS-H3510 or JIS-H3100 can be used as a copper foil material satisfying such conditions.

  In addition, since Young's modulus can be easily controlled, alloy elements such as Sn, Ag, In, Au, Cr, Zr, Mg, and Pd can be added to tough pitch copper and oxygen-free copper. If the total content of these elements exceeds 0.05% by mass, the strength is further improved, but the elongation may decrease and workability may deteriorate, so the total content of these elements is 0.05. It is preferable to set it as the mass% or less. More preferably, the total content of the alloy elements is 0.03% by mass or less. Although the lower limit of the total content of the alloy elements is not particularly limited, for example, 0.001% by mass can be set as the lower limit. If the total content is less than 0.001% by mass, the desired effect cannot be obtained, and the content may be difficult to control because the content is small. Preferably, the lower limit of the total amount of the alloy elements is 0.003% by mass or more, more preferably 0.004% by mass or more, and most preferably 0.005% by mass or more.

(2. Thickness of copper foil)
There is no restriction | limiting in particular about the thickness of the rolled copper foil which can be used for this invention, What is necessary is just to adjust suitably to the thickness suitable for printed wiring boards. When used as a conductive material for FPC, it is possible to obtain higher flexibility and vibration resistance when the copper foil is thinned. On the other hand, if it is too thin, wrinkles are likely to occur. Can be about. For the purpose of forming a fine pattern, it is 30 μm or less, preferably 20 μm or less, and typically about 5 to 20 μm.

(3. Difference in Young's modulus before and after recrystallization ΔE)
When manufacturing a copper-clad laminate, heat treatment is performed to bond the copper foil and the insulating substrate. Usually, at this time, the copper foil structure changes from a rolled structure to a recrystallized structure, which softens and bends. Will improve. In the rolled copper foil according to the present invention, when the Young's modulus in the rolling direction at 25 ° C. is E1, and after heat treatment at 350 ° C. for 1 second, the Young's modulus in the rolling direction at 25 ° C. is E2, the Young's modulus E1 One feature is that the difference ΔE = E1−E2 between the Young's modulus E2 and the Young's modulus E2 is 12 to 33 GPa. The heat treatment at 350 ° C. for 1 second is a typical heating condition when the copper foil is bonded to the insulating substrate, and is therefore the heat treatment condition in the present invention. The Young's modulus after recrystallization greatly depends on the heat treatment conditions, and is greatly different between the heat treatment in several seconds and the heat treatment time of 10 seconds or more.

  In the copper clad laminate production line, due to heat treatment in the middle, the copper foil is tensioned in a state where a recrystallized structure and a rolled structure before recrystallization are mixed. At this time, if there is an excessive difference in ΔE, the deformation is larger in the portion where E is small than the portion where E is large, and wrinkles are likely to occur at the boundary between the portion where E is large and the portion where E is small. Therefore, ΔE is preferably small, and in order to effectively suppress wrinkles, it is necessary to be 33 GPa or less, preferably 30 GPa or less, more preferably 28 GPa or less. However, if ΔE is too small, recrystallization is often inadequate and the bending properties are deteriorated. Therefore, ΔE needs to be 12 GPa or more, and preferably 15 GPa or more.

(4. Young's modulus before recrystallization)
The rolled copper foil according to the present invention is generally in a state after rolling and has a rolled structure. However, there may be a thermal history that does not cause recrystallization due to drying after degreasing. One feature of the rolled copper foil according to the present invention is that, at this point, the Young's modulus E1 in the rolling direction at 25 ° C. is 80 to 130 GPa. When E1 is less than 80 GPa, wrinkles are likely to occur during rolling and degreasing in the copper foil production process, and the production is inferior. E1 is preferably 85 GPa or more, more preferably 95 GPa or more. On the other hand, if E1 is greater than 130 GPa, ΔE tends to be greater than 33 GPa after recrystallization, and the generation of wrinkles accompanying changes in physical properties before and after recrystallization cannot be suppressed. E1 is preferably 125 GPa or less, more preferably 120 GPa or less.

(5. Young's modulus after recrystallization)
As described above, the structure of the copper foil changes from the rolled structure to the recrystallized structure by the heat treatment when manufacturing the copper-clad laminate. One feature of the rolled copper foil according to the present invention is that the Young's modulus E2 in the rolling direction at 25 ° C. is 60 to 110 GPa after heat treatment at 350 ° C. for 1 second. From the viewpoint of the bending characteristics, E2 is preferably small, and specifically, it is set to 110 GPa or less. E2 is preferably 100 GPa or less, more preferably 90 GPa or less. However, if E2 is too small, ΔE tends to increase, so E2 was set to 60 GPa or more. E2 is preferably 65 GPa or more, more preferably 70 GPa or more.

(6. Cube texture)
From the viewpoint of obtaining excellent bending properties, it is preferable that a cubic texture ({100} <001> orientation) is developed in the metal structure of the copper foil after recrystallization. The degree of development of the cubic texture is determined by the X-ray diffraction intensity ratio I / I ₀ of the (200) plane (I: the diffraction intensity of the 200 plane of the copper foil, I ₀ : the (200) plane of the copper powder having a random orientation. It can be expressed by the magnitude of (diffraction intensity), and the larger this value, the more the cube orientation is developed. I / I ₀ is preferably 10 or more, more preferably 15 or more. However, if I / I ₀ becomes excessively high, the etching rate is different between the dishdown (soft-etched defect / (200) plane and other orientation planes), and within the crystal grains. I / I ₀ is preferably 30 or less, and more preferably 25 or less. When I / Io is 60 or more, since the (200) plane is developed on the entire surface, dishdown hardly occurs. However, when I / Io is 60 or more, ΔE increases, which is not preferable.
A pure copper standard powder is used as the copper powder, which is defined as a copper powder having a purity of 99.5% with a 325 mesh (JIS Z8801).

(7. Manufacturing method of rolled copper foil)
In the manufacturing process of the rolled copper foil, after melting a pure copper raw material of electrolytic copper and adding an alloy element, the molten metal is cast to manufacture an ingot having a thickness of about 100 to 300 mm. The ingot is annealed for homogenization, then hot rolled to a plate of about 5 to 20 mm, then cold rolled and annealed repeatedly to make it thinner, and finally cold rolled (final cold To a foil with a predetermined thickness. The copper foil after the final cold rolling may be subjected to various surface treatments such as degreasing, rust prevention, and roughening treatment for improving adhesion to the insulating substrate.

  In producing the rolled copper foil according to the present invention, cold rolling and annealing are repeated, but in all the annealing performed after cold rolling, it is about 0.1 to 0.5 times the yield strength at the annealing temperature of the material. It is good to carry out while applying the tension. This is because the structure after final rolling is controlled by controlling the recrystallized structure formed by annealing after cold rolling, and E1, E2, and ΔE are controlled. When tension is applied during annealing, the amount of heat required for recrystallization is greater than when there is no tension. In addition, the crystal grains tend to grow large after recrystallization. When the tension is larger than 0.5 times the yield strength, secondary recrystallization is likely to occur partially, and burrs are likely to occur at crystal grain portions coarsened by subsequent rolling. If it is less than 0.1 times, E2 tends to be small and ΔE tends to be larger than 33 GPa. Moreover, as conditions for annealing, the amount of heat necessary for recrystallization may be added, but examples include 1 to 2000 s at 350 to 800 ° C. When the temperature is low, the annealing time may be lengthened, and when the temperature is high, the annealing time may be shortened. Further, the final cold rolling is preferably performed at a working degree of 90 to 99.7% so that the entire surface is uniformly recrystallized by heat at the time of producing the copper-clad laminate. Here, the working degree r (%) is defined by r = (to-t) / to × 100 (t: thickness after rolling, to: thickness before rolling, and thickness after annealing). Further, in the final cold rolling, it is preferable that the degree of work per pass is 10 to 40%. If it is less than 10%, E2 tends to be small, and ΔE tends to be larger than 33 GPa. If it is 40% or more, E2 tends to be large, and ΔE tends to be smaller than 12. Here, the processing degree r (%) per pass is defined by r = (t1−t2) / t1 × 100 (t1: thickness on the rolling roll entering side, t2: thickness on the rolling roll exit side).

(8. Production of printed wiring boards)
A printed wiring board (PWB) can be manufactured according to a conventional method using the copper foil according to the present invention. Below, the example of manufacture of a printed wiring board is shown.

  First, a copper-clad laminate is manufactured by bonding a copper foil and an insulating substrate. The insulating substrate on which the copper foil is laminated is not particularly limited as long as it has characteristics applicable to flexible printed wiring boards, electromagnetic shielding materials, reflectors for lighting equipment, wiring, and heat sinks, but polyester films and polyimide films A liquid crystal polymer film can be used.

  In the case of a flexible printed wiring board (FPC), a surface having a polyimide film or polyester film and a copper foil coating layer can be bonded using an epoxy or acrylic adhesive (three-layer structure). In addition, as a method without using an adhesive (two-layer structure), a polyimide varnish (polyamic acid varnish), which is a polyimide precursor, is applied to a surface having a coating layer of copper foil, and imidized by heating. And a lamination method in which a thermoplastic polyimide is applied on a polyimide film, a surface having a copper foil coating layer is superimposed thereon, and heated and pressed. In the casting method, it is also effective to apply an anchor coating material such as thermoplastic polyimide in advance before applying the polyimide varnish.

  To manufacture a double-sided copper-clad laminate with copper foil on both sides of the resin film on an industrial scale, the long copper foil is bonded to an insulating substrate while flowing on a roll-to-roll line. The heat treatment for bonding is performed, for example, by passing through a nip roll heated to 300 to 400 ° C. at a speed of about 0.5 to 10 m / min. According to the rolled copper foil which concerns on this invention, since the Young's modulus before and behind recrystallization by heating is controlled, generation | occurrence | production of a wrinkle is suppressed. For this reason, improvement in productivity and yield can be expected.

  The copper-clad laminate according to the present invention can be used for various printed wiring boards (PWB) and is not particularly limited. For example, from the viewpoint of the number of layers of the conductor pattern, single-sided PWB, double-sided PWB, multilayer It can be applied to PWB (3 layers or more), and can be applied to flexible PWB (FPC) and rigid flex PWB from the viewpoint of the type of insulating substrate material.

  The process for producing a printed wiring board from a copper clad laminate may be performed by a method well known to those skilled in the art. By spraying on the copper foil surface, the unnecessary copper foil can be removed to form a conductor pattern, and then the etching resist can be peeled and removed to expose the conductor pattern.

  Hereinafter, description will be made based on Examples and Comparative Examples. In addition, a present Example is an example to the last, and is not restrict | limited only to this example.

(Example 1)
Electrolytic copper was melted in a vacuum, and then elements having the compositions shown in Table 1 were added to cast an ingot having a thickness of 50 mm in the air or in an Ar atmosphere. The oxygen content was 150-300 ppm by mass when cast in the atmosphere, and less than 15 ppm by mass when cast in an Ar atmosphere. The obtained ingot was subjected to homogenization annealing at a temperature of 800 ° C. for 10 hours, and then subjected to hot rolling. Next, after removing the oxide scale on the surface by chamfering, cold rolling and recrystallization annealing were repeated, and long copper foil samples having respective foil thicknesses shown in Table 1 were prepared by final cold rolling.

  In the above production process, in all of the examples and comparative examples, all recrystallization annealing after cold rolling was performed under heating conditions at 650 ° C. for 10 seconds. In the examples, the samples of each example at 650 ° C. This was performed while applying a tension of 0.3 to the proof stress in the rolling direction, and in the comparative example, the tension was not applied. Further, in the examples, the final rolling work degree was set to 95% to 99.5%, and the working degree per pass was controlled to fall within 15 to 35% in all passes of the final cold rolling, In all of the comparative examples, the final rolling degree is 92% to 99.5%. In all the passes of the final cold rolling, the comparative example 2 has a working degree per pass of 5 to 15%, and the comparative example 3 has one pass. The degree of processing was set to 15 to 35%, and in Comparative Example 1, it was controlled to fall within 30 to 50%. Further, the temperature of the rolling oil during the final cold rolling was not particularly controlled.

  The following characteristics were evaluated with respect to the obtained copper foil sample.

(Measurement of Young's modulus)
The Young's modulus (E1) in the rolling direction of the rolled copper foil sample was measured according to the vibration method (JIS Z2280) except that the temperature condition was 25 ° C. Also, the copper foil sample was subjected to a heat press (press pressure: 30 MPa) at 350 ° C. for 1 second, and the Young's modulus (E2) in the rolling direction of the copper foil after the heat treatment was measured in the same manner under a temperature condition of 25 ° C. It was measured. As a measuring device, a cantilever type thin plate Young's modulus measuring device, TE-RT manufactured by Nippon Techno Plus Co., Ltd. was used. The sample had a strip shape with a width of 3.2 mm and a length of 15 mm, and the vibration length was 10 mm. The Young's modulus was measured 10 times and the average value was taken as the measured value.

(Measurement of I / I ₀ )
The integrated value of the diffraction intensity of the (200) plane in the X-ray diffraction of the rolled surface (model RINT-2500, manufactured by Rigaku Corporation) for the copper foil sample after being heated and pressed at 350 ° C. for 1 second (press pressure: 30 MPa). (I) was determined. This value was divided by the integral value (I ₀ ) of (200) diffraction intensity of finely powdered copper (325 mesh), which had been measured in advance, to calculate an I / I ₀ value. X-ray diffraction was performed using a Co tube, and the integrated value of the diffraction intensity of the (200) plane was measured in the range of 2θ = 57 to 63 ° (θ is the diffraction angle).

(Wrinkle suppression)
Rolled copper foil sample and 12 μm thick polyimide film (Kapton EN) were coated with a commercially available thermoplastic polyimide adhesive and dried, and a 15 μm thick polyimide film with adhesive was laminated and heated to 350 ° C. A copper-clad laminate was manufactured by thermocompression bonding in a laminating test in which the sheet was passed through a nip roll. The tension of copper foil unwinding was changed to 30 MPa, the sheet passing speed was changed from 0.5 to 10 m / min, and wrinkles were suppressed at the time of thermocompression bonding at all speeds, with wrinkle suppression x, 0.5 to 3 m / min. Wrinkles were suppressed when the wrinkles did not enter, and wrinkles were suppressed when the wrinkles did not enter at 0.5 to 1 m / min, and wrinkles were suppressed when no wrinkles occurred at all speeds.

(Soft etching)
After soft etching, the appearance was inspected with an optical microscope. Although the surface with a smaller area ratio called dish down is surrounded by the surface with the larger area, the number of locations where the minor axis exceeds 50 μm was counted. Etching is performed for 2 minutes at room temperature using Adeka Tech CL-8 (manufactured by Adeka Co., Ltd.) as a soft etchant, and an image obtained by photographing the surface of the observation range of 1 mm square after etching with an optical microscope is converted into light and dark. The percentage of was calculated. Although the surface with the smaller volume fraction is surrounded by the surface with the larger volume, the number of locations where the inner minor axis exceeds 50 μm was counted. When the location was 7 or less, the etching property was the best (◎), and when it was 10 or less, the etching property was good (◯), and when it was more than 10, the etching property was poor (x).

(Bending fatigue properties)
A 27 μm thick resin layer formed by applying 2 μm of a commercially available thermoplastic PI adhesive to a polyimide film (trade name: Kapton EN) having a thickness of 25 μm and drying it is laminated on a copper foil, and a copper-clad laminate by vacuum hot pressing. Was made. The bending fatigue life was measured by the bending test apparatus shown in FIG. This apparatus has a structure in which a vibration transmitting member 3 is coupled to an oscillation driver 4, and the device under test 1 is connected to the apparatus at a total of four points: a screw 2 portion indicated by an arrow and a tip portion of the vibration portion 3. Fixed. When the vibration part 3 is driven up and down, the intermediate part of the DUT 1 is bent into a hairpin shape with a predetermined radius of curvature r. In this test, the number of times until breakage when bending was repeated under the following conditions was determined.
The test conditions are as follows: Specimen width: 12.7 mm, Specimen length: 200 mm, Specimen sampling direction: Sampled so that the length direction of the specimen is parallel to the rolling direction, radius of curvature r: 2 0.5 mm, vibration stroke: 25 mm, vibration speed: 1500 times / minute.
When the bending fatigue life is 600,000 times or more, ◎, when it is 500,000 times or more, ○, when it is less than 500,000 times, ×.

(Appearance after final rolling)
After final rolling and degreasing, the surface of the copper foil is observed with a commercially available CCD line sensor at 600 m ² , and there is no streak that has a different color tone from other places. A case where one or more streaks having a color tone different from that of other places occurred and one or more pinholes were formed in the streaky portion was designated as Δ.

The results are shown in Table 1. In Examples 1 to 24, since E1, E2, and ΔE were all appropriately controlled, generation of wrinkles was suppressed before and after the heat treatment. Moreover, in Examples 1-24, it was excellent in the flexibility and the wrinkle at the time of rolling and degreasing was also suppressed. Further, in Examples 1 to 21, 23, and 24, I / I ₀ was also appropriately controlled, and the soft etching property was excellent.
On the other hand, in Comparative Example 1, since the degree of processing per pass of the final cold rolling was large, ΔE was too small, so that the flexibility was inferior to that of the example. In Comparative Example 2, since the degree of processing per one pass of final rolling was too low, ΔE was too large, so that wrinkles due to heat treatment were observed. In Comparative Example 3, since ΔE was too large because no tension was applied in the intermediate annealing, generation of wrinkles due to heat treatment was observed.

(Example 2: Comparative example corresponding to the copper foil described in JP2012-001786A)
The electrolytic copper was dissolved in a vacuum, and then elements having the compositions shown in Table 2 were added to cast the ingot in the atmosphere. What was cast in air | atmosphere was 150-300 mass ppm for oxygen content. The obtained ingot was heated at a temperature of 850 ° C. for 3 hours and then hot-rolled. Next, after removing the oxide scale on the surface by chamfering, cold rolling and recrystallization annealing were repeated, and a long copper foil sample having a thickness of 12 μm was produced by the final cold rolling.
In the above manufacturing process, all recrystallization annealing after cold rolling was performed at 650 ° C. for 10 seconds without applying tension. Further, the final rolling work degree was set to 95% to 99.9%. Moreover, the temperature of the rolling oil at the time of final cold rolling was adjusted to the range of 30-40 degreeC.

  The obtained copper foil sample was evaluated for characteristics in the same manner as in Example 1. Further, for reference, Young's modulus (E3) after heating and pressing at 360 ° C. for 6 minutes (press pressure: 30 MPa) was measured in the same manner as in Example 1 under a temperature condition of 25 ° C. The results are shown in Table 2. In Comparative Examples 4 and 6, wrinkles due to heat treatment were observed because ΔE was too large because no tension was applied by recrystallization annealing and the degree of processing per pass in final rolling was not controlled. . In Comparative Example 5, since the degree of work of the final rolling was too large, ΔE was too small, so that the flexibility was inferior to that of the example.

(Example 3: Comparative example corresponding to the copper foil described in JP2009-158382A)
Electro-copper was melted in a vacuum and an ingot was cast in an Ar atmosphere. The obtained ingot was heated and then hot-rolled. Next, after removing the oxide scale on the surface by chamfering, cold rolling and recrystallization annealing were repeated, and a long copper foil sample having a thickness of 18 μm was produced by the final cold rolling. However, no tension was applied in the recrystallization annealing, and the degree of processing per pass in the final rolling was not controlled.

  The obtained copper foil sample was evaluated for characteristics in the same manner as in Example 1. For reference, a tensile test was performed before and after heating press at 300 ° C. for 5 minutes (press pressure: 30 MPa), and the slopes near the origin in the stress-strain curve (E4 before heating press, E5 after heating press). Measurement was performed under a temperature condition of 25 ° C. The results are shown in Table 3. In Comparative Examples 7 and 8, since no tension was applied by recrystallization annealing, and the degree of processing per pass in the final rolling was not controlled, ΔE was too large, so that generation of wrinkles due to heat treatment was observed. .

1. 1. Test object Screw 3. 3. Vibration transmission member Oscillation driver

Claims (5)

  The Young's modulus E1 in the rolling direction at 25 ° C. is E1 = 80 to 130 GPa, and after heat treatment at 350 ° C. for 1 second, the Young's modulus E2 in the rolling direction at 25 ° C. is E2 = 60 to 110 GPa. A rolled copper foil for printed wiring boards in which the difference ΔE = E1−E2 between E1 and Young's modulus E2 is 12 to 33 GPa. The 200 diffraction intensity (I) obtained by X-ray diffraction of the rolled surface after heat treatment at 350 ° C. for 1 second is 10 times the 200 diffraction intensity (I ₀ ) obtained by X-ray diffraction of fine powder copper. The rolled copper foil for printed wiring boards according to claim 1, wherein ≦ I / I ₀ ≦ 30.   The Young's modulus E1 in the rolling direction at 25 ° C. is E1 = 85 to 125 GPa, and after heat treatment at 350 ° C. for 1 second, the Young's modulus E2 in the rolling direction at 25 ° C. is E2 = 65 to 100 GPa. Or the rolled copper foil for printed wiring boards of 2. The copper clad laminated board provided with the rolled copper foil for printed wiring boards as described in any one of Claims 1-3 . A printed wiring board made of the copper clad laminate according to claim 4 .

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