JP2011094200A - Copper or copper alloy foil, and method for manufacturing double-sided copper-clad laminate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper or copper alloy foil which can reduce wrinkles or creases occurring when used for a double-sided copper-clad laminate, and to provide a method for manufacturing a double-sided copper-clad laminate using the same. <P>SOLUTION: The copper or copper alloy foils 4 and 6 are used for the double-sided copper-clad laminate 8, satisfy ¾10,000×(E<SB>A</SB>×/2)¾≤YS<SB>A</SB>when σ<SB>A</SB>is (E<SB>A</SB>×ΔL<SB>B</SB>)/2×1,000, and have the number of bending times of 400,000 or more, wherein E<SB>A</SB>is Young's modulus (of which the unit is GPa) in a width direction after the copper or copper alloy foil has been held at 350°C for 30 min and cooled to room temperature; ΔL<SB>A</SB>is a dimensional change rate (of which the unit is ppm, and in which shrinkage is defined as positive value) in the width direction of the copper or copper alloy foil which has been heated to 350°C from room temperature, held at the temperature for 30 min and cooled to room temperature; YS<SB>A</SB>is 0.2% yield strength (of which the unit is MPa) of the copper or copper alloy foil in a tensile test; and the number of bending times is a value measured at an end point at which the electric resistance has increased from the initial stage by 20%, with the use of an IPC sliding bending tester. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is used for, for example, a flexible printed circuit (FPC), and is suitable for a double-sided copper-clad laminate in which copper or copper alloy foil is laminated on both sides of a resin layer, and It is related with the manufacturing method of the used double-sided copper clad laminated board.

The copper-clad laminate (CCL) used for flexible wiring boards (FPC) is a single-sided copper-clad laminate in which copper foil is laminated on one side of the resin layer, and a double-sided copper-clad laminate in which copper foil is laminated on both sides of the resin layer A plate (hereinafter referred to as “double-sided CCL”) is used. A double-sided CCL with a circuit formed on a double-sided CCL is a double-sided flexible wiring board, and the use of double-sided CCL tends to increase because it is easy to realize finer circuits and space-saving FPC.
As a method for producing such a double-sided CCL, a method is known in which a varnish of a resin composition is cast on one side of a copper foil and another copper foil is thermocompression bonded to the resin side after heat curing (Patent Document 1). Moreover, the method of thermocompression bonding copper foil to the front and back of a polyimide film having a thermoplastic polyimide layer on both sides at the same time, after thermocompression bonding of the copper foil to one surface of a polyimide film having a thermoplastic polyimide layer, on the opposite side of the copper foil A method of applying a thermoplastic polyimide layer to the polyimide film surface and thermocompression bonding another copper foil on the surface, casting a varnish that is a polyimide precursor on one side of the copper foil and curing, then on the opposite side of the copper foil There is a method in which a thermoplastic polyimide layer is formed on the resin surface and another copper foil is thermocompression bonded to the surface.

Japanese Patent Laid-Open No. 05-212824

Here, except when the copper foil is laminated on both sides of the resin layer (such as the above polyimide film) at the same time, the first copper foil laminated with the resin layer (first copper foil) Heated to a temperature of 300 ° C or higher and once cooled. Further, when another copper foil (second copper foil) is subsequently laminated on the opposite surface of the resin layer, the first copper foil is similarly reheated and cooled.
However, after the second copper foil is laminated and heated, when it is cooled, wrinkles and creases may occur in parallel with the length direction of the first copper foil and usually at the center in the width direction. These wrinkles and creases are difficult to completely eliminate even if the lamination conditions of the second copper foil and the heating conditions during lamination (thermocompression conditions, tension, etc.) are adjusted. And since such wrinkles and me have different heat histories during lamination on the first copper foil and the second copper foil, when the second copper foil is laminated and heated, it is cooled. It is considered that this occurs when the dimensional change rates of the two copper foils existing across the resin layer are different due to the temperature change, and the copper foil cannot withstand the stress caused thereby.

  That is, the present invention has been made to solve the above problems, and copper or copper alloy foil capable of suppressing wrinkles and creases when used in a double-sided copper-clad laminate, and double-sided using the same It aims at providing the manufacturing method of a copper clad laminated board.

As a result of various studies by the inventors, when producing double-sided CCL, a difference in dimensional change occurs between the two copper foils due to different thermal histories applied to the first copper foil and the second copper foil. It has been found that wrinkles and creases can be suppressed by adjusting the characteristics of both copper foils so that the copper foil does not buckle even if stress is generated in the foil.

That is, the copper or copper alloy foil of the present invention is used for a double-sided copper-clad laminate, and when σ _A = (E _A × ΔL _A ) / 2 × 1000, | 10 × σ _A | ≦ YS _A The number of flexing is 400,000 times or more.
However, E _A: After cooling to room temperature and held the copper or 30 minutes copper alloy foil at 350 ° C., the Young's modulus in the transverse direction of (the unit GPa), [Delta] L _A: temperature was raised to 350 ° C. from room temperature, 30 minutes held (the unit ppm, the shrinkage and positive values) the copper or the width direction dimensional change rate of the copper alloy foil when cooled to room temperature, YS _a: of the copper or copper alloy foil in a tensile test 0.2% yield strength (Unit: MPa)
Number of bendings: Using an IPC sliding bending tester, the foil was cut into strips with a width of 12.5 mm and a length of 200 mm and heat-treated at 350 ° C. for 0.5 hours. The bending radius was 18 μm. 1.5 mm in the case, and 1 mm in the case where the foil thickness is 12 μm, the test piece was subjected to repeated sliding 100 times per minute, and the number of bendings where the electrical resistance increased by 20% from the initial point was the number of times

The copper or copper alloy foil is a rolled foil, the final cold rolling degree R (%) is 93.0% or more, and the average crystal grain size GS (μm) after the final annealing is GS ≦ 3.08 × R-260 is preferable.
It is preferred [Delta] L _A is not more than 145 ppm.

  The method for producing a double-sided copper-clad laminate of the present invention includes a first step of forming a resin layer on one side of the copper or copper alloy foil to obtain a single-sided copper-clad laminate, and the resin of the single-sided copper-clad laminate. And laminating another copper or copper alloy foil on the layer side and heating to obtain a double-sided copper-clad laminate.

  According to the present invention, when producing a double-sided copper-clad laminate, wrinkles and creases can be suppressed.

It is a figure which shows the manufacturing method of the double-sided copper clad laminated board which concerns on embodiment of this invention. It is sectional drawing which shows the structural example of a double-sided copper clad laminated board. It is a figure which shows the state which a wrinkle (ole) generate | occur | produces in the 1st copper or copper alloy foil with the heat | fever added at the time of manufacture of a double-sided copper clad laminated board.

Hereinafter, the manufacturing method of the double-sided copper clad laminated board using the copper or copper alloy foil which concerns on embodiment of this invention is demonstrated. In the present invention,% means mass% (mass%) unless otherwise specified. FIG. 1 shows a method for manufacturing a double-sided metal-clad laminate 8.
In FIG. 1, first, coiled first copper or copper alloy foil 4 is continuously unwound, and application rolls 10 and 11 are used on one side of the unwound first copper or copper alloy foil 4. The varnish-like resin composition 2a is continuously applied with a predetermined thickness. The resin composition 2a becomes the resin layer 2 after curing. Next, the 1st copper or copper alloy foil 4 which apply | coated resin composition 2a is introduce | transduced into the drying apparatus 15, and the resin composition 2a is hardened (or semi-hardened). In this way, a resin layer is formed on one side of the first copper or copper alloy foil 4 to obtain a single-sided copper-clad laminate (first step). In some cases, after the first step is completed, the coil is wound into a coil shape and the process proceeds to the second step. In addition, although it heats, when forming a resin layer in the single side | surface of the 1st copper or copper alloy foil 4, it heats after apply | coating the above-mentioned resin composition, for example, already becomes a resin layer like a resin film. You may thermocompression-bond what is to the one side of the 1st copper or copper alloy foil 4. FIG. In general, the heating temperature in the first step is equal to or higher than the heating temperature in the second step. Next, the coiled second copper or copper alloy foil 6 is continuously unwound, for example, between the first copper or copper alloy foil 4 and the first roll between the laminate rolls 20 and 21 heated to 350 to 400 ° C. Two copper or copper alloy foils 6 are continuously passed through. At this time, the second copper or copper alloy foil 6 is laminated on the resin layer 2 side of the first copper or copper alloy foil 4 and heated to obtain a double-sided copper clad laminate 8 (second step). The double-sided copper clad laminate 8 is appropriately wound around a coil.

As shown in FIG. 2, the double-sided copper-clad laminate 8 is configured by laminating a second copper or copper alloy foil 6 on the resin layer 2 side of the first copper or copper alloy foil 4.
Examples of the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 include pure copper, tough pitch copper (JIS-1100), oxygen-free copper (JIS-1020), and these pure copper and tough pitch copper. And oxygen-free copper added with Sn and / or Ag in a total amount of 40 to 400 mass ppm. The thicknesses of the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 can be, for example, about 6 to 18 μm. The first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 are the same. The first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 may be rolled foils or electrolytic foils.
As the resin layer 2, polyimide; PET (polyethylene terephthalate); thermosetting resin such as epoxy resin and phenol resin; and thermoplastic resin such as saturated polyester resin can be used, but not limited thereto. Also, a varnish (for example, a polyamic acid solution of a polyimide precursor) in which the components of the resin layer are dissolved in a solvent is applied to one side of the first copper or copper alloy foil 4 and the solvent is removed by heating. The reaction (for example, imidization reaction) may be advanced and cured. The thickness of the resin layer 2 can be about 1-15 micrometers, for example.

Next, the characteristics of the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 which are characteristic portions of the present invention will be described.
After forming a resin layer on one side of the first copper or copper alloy foil 4, when producing a double-sided CCL by laminating the second copper or copper alloy foil 6, two copper or copper alloy foils sandwiching the resin The stress caused by the difference in dimensional change between 4 and 6 is expressed as follows.
First, the first copper or copper alloy foil 4 is laminated on the double-sided CCL at a temperature T ₁ (T ₁ is a heating temperature when the second copper or copper alloy foil 6 is laminated) and cooled to T _2. The stress σ _A applied to
_{σ A = E A × E B} / (E A + E B) × (α B × (T 1 -T 2) + ΔL B - (α A × (T 1 -T 2) + ΔL A)) × 1000 (1) It is represented by Note that the dimensional change Δ is a positive shrinkage and a change in the width direction (coil width direction when CCL is continuously manufactured from a copper or copper alloy foil coil).
Here, since the copper or copper alloy foil used for CCL is close to pure copper, the thermal expansion coefficient α (subscripts A and B are the first copper or copper alloy foil, respectively) even if some additive components are included. 4, which represents the second copper or copper alloy foil 6) can be regarded as the same (α _A ≈α _B ). Therefore, Equation 1 is
represented by _{σ A = E A × E B} / (E A + E B) × (ΔL A -ΔL B) × 1000 (2).

However, E _A : The first copper or copper alloy foil is held at 350 ° C. for 30 minutes and cooled to room temperature, and then held at 350 ° C. for 30 minutes and cooled to room temperature. Young's modulus in the width direction of the copper or copper alloy foil (unit: GPa), E _B : the second heat history by holding the second copper or copper alloy foil at 350 ° C. for 30 minutes and cooling to room temperature in the temperature was raised to 350 ° C. from room temperature, based on the dimensions when cooled to room temperature and held for 30 minutes, again 350 ° _C.: copper or the Young's modulus in the transverse direction of the copper alloy foil (the unit GPa), [Delta] L a Dimensional change rate in the width direction of the first copper or copper alloy foil after holding for 30 minutes and cooling to room temperature (unit is ppm, shrinkage is a positive value), ΔL _B : temperature rise from room temperature to 350 ° C. Dimensional change rate in the width direction of the second copper or copper alloy foil after holding for 30 minutes and cooling to room temperature (unit is ppm, shrinkage is positive) The value), it is.
In addition, room temperature is 25-35 degreeC (normally 25 degreeC).

That is, if the Young's modulus of both the copper or copper alloy foils 4 and 6 is reduced and the difference in the dimensional change rate between the copper or copper alloy foils 4 and 6 (ΔL _A −ΔL _B ) is reduced, the stress σ _A is reduced. Therefore, wrinkles and creases during double-sided CCL manufacturing are less likely to occur.

Here, even if the same copper or copper alloy foils 4 and 6 are used, a difference in dimensional change rate (ΔL _A −ΔL _B ) is generated. Therefore, this difference is not caused by thermal expansion. it is obvious. When heat is applied to the metal, structural changes such as recrystallization and recovery occur. Therefore, when the metal is heated and cooled, it becomes shorter (thermal shrinkage) or longer (thermal expansion) than the original size. Further, even if the metal once heated and cooled is heated again to the same temperature or lower and then cooled, neither thermal shrinkage nor thermal elongation occurs. These phenomena occur in both rolled foil and electrolytic foil. However, rolled foil is more strained by rolling, and depending on the components of the foil, the heat applied during CCL production can change the rolled structure to the recrystallized structure. As it changes, thermal shrinkage or thermal elongation increases.

FIG. 3 shows a state in which the above-described thermal expansion and contraction occur due to heat applied during CCL production, and wrinkles (ole) 100 are generated in the first copper or copper alloy foil 4.
First, when producing a single-sided copper clad laminate in the first step, when the first copper or copper alloy foil 4 is heated and cooled, it heat shrinks smaller than the original length. Next, when producing a double-sided copper clad laminate in the second step, when the second copper or copper alloy foil 6 is heated and cooled, it tends to shrink less than the original length (arrow in FIG. 3). ). On the other hand, the first copper or copper alloy foil 4 which has already been heat-shrinked in the first step hardly heat-shrinks in the second step (arrow in FIG. 3).
Therefore, during the cooling after the heating in the second step, a compressive stress is applied to the first copper or copper alloy foil 4 with a force that the second copper or copper alloy foil 6 tends to shrink. And the 1st copper or copper alloy foil 4 buckles (it wrinkles and I generate | occur | produce) without being able to endure this compressive stress.

However, when compressive stress is applied to the first copper or copper alloy foil 4 side, if the proof stress of the copper foil is greater than the compressive stress (σ _{A in} Formula 2), buckling does not occur, and wrinkles and creases are unlikely to occur. Become. Usually, the resistance to compression of the copper foil cannot be obtained, but the boundary value of whether or not buckling occurs can be substituted with the resistance to tension (YS). That is, if the first copper or copper alloy foil 4 is selected so that YS is equal to or greater than σ _A , it is considered that wrinkles and creases will not occur.
And, as a result of experimentally determining the conditions in which wrinkles and creases do not occur when the present inventors manufacture a double-sided copper-clad laminate, for σ _A in Equation 2,
| 10 × σ _A | ≦ YS _A (3)
It was found that if the first copper or copper alloy foil 4 was selected so that wrinkles and creases would not occur.
On the other hand, with respect to when the compression stress is applied to the second copper or copper alloy foil 6, of formula 2 sigma _B,
| 10 × σ _B | ≦ YS _B (4)
It was found that if the second copper or copper alloy foil 6 was selected so that wrinkles and creases would not occur. However, it is common that compressive stress is applied to the first copper or copper alloy foil 4.

In order to satisfy Equation 3 (or Equation 4), it is better that σ _A (σ _B ), that is, the difference in dimensional change rate (ΔL _A −ΔL _B ) is smaller. For this purpose, in the first step, the first copper or The smaller the difference between the heat received by the copper alloy foil 4 and the heat received by the second copper or copper alloy foil 6 in the second step, the better. In addition, the smaller the strain that the first copper or copper alloy foil 4 receives in the first step, the smaller the difference in dimensional change rate (ΔL _A −ΔL _B ).
Therefore, as a specific method satisfying the expressions 3 and 4, 1) preheating the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 or 2) first. When the copper or copper alloy foil 4 and the second copper or copper alloy foil 6 are rolled foils, rolling should be performed at a low degree of work. 3) Tension at the time of rolling set from the thickness and mechanical properties of the foil 4) Use of electrolytic foil for the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 can be mentioned. However, if it is generally considered that compressive stress is applied to the first copper or copper alloy foil 4 side, the methods 1) to 4) may be applied only to the second copper or copper alloy foil 6.

With respect to the method 1), pure copper is a metal having a face-centered cubic structure, and it is known that when recrystallized by heating, the cubic orientation develops and the flexibility is improved. Copper foils with developed cube orientation have a low Young's modulus and a low 0.2% proof stress in the tensile test. That is, it can be said that a copper foil having such a cube orientation is most susceptible to wrinkles when double-sided CCL is manufactured (when the second step is performed). For example, when the pure copper foil is cooled by being held at 350 ° C. for 30 minutes, it has been found through experiments by the inventors that the Young's modulus is about 70 GPa and the 0.2% proof stress is about 50 MPa. Thus, even if the copper or copper alloy foil having a small proof stress is heated again to about 350 ° C. and cooled, the dimensional change is considered to be almost zero.
Accordingly, the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 are the same (E _A ≈E _B , | σ _A | ≈ | σ _B |), ΔL _A ≈0 Is approximated by
σ _A = (E _A × ΔL _B ) / 2 × 1000 (5)
It is represented by From Equation 3 and Equation 5,
| 10000 × (E _A × ΔL _B / 2) | ≦ YS _A (6)
Therefore, the double-sided CCL may be manufactured using a copper or copper alloy foil that satisfies Equation 6.
Further, if E _A = 70 Gpa and YS _A = 50 MPa are substituted into Formula 5 from the above experimental results, ΔL _B = 143 (ppm) is obtained. That is, if at least the second copper or copper alloy foil 6 is heated before use and ΔL _B ≦ 143 (ppm) is used, both flexibility and wrinkles and wrinkles are less likely to occur. The heating condition of the second copper or copper alloy foil 6 may be about 1 second to 10 hours at 50 ° C. to 200 ° C., but is not limited thereto. For example, heating conditions include holding at 60 ° C. for 3 hours and holding at 130 ° C. for 3 seconds. That is, such heat treatment may be preliminarily applied to the copper or copper alloy foil and used for the production of double-sided CCL.

Next, with respect to the above method 2), the strain of the rolled foil varies depending on the degree of rolling process after final annealing, the amount of rolling reduction in one pass, the tension, the processing temperature, and the like. However, the amount of reduction and tension depend on the thickness of the foil to be processed and the performance of the rolling mill, and are difficult to define uniformly. Also, the higher the processing temperature, the smaller the strain, but the rolling oil plays the role of coolant during rolling, and it is difficult to define the instantaneous processing temperature.
Therefore, the conditions required for foil from the degree of rolling are specified. Here, when the rolling degree is reduced, the distortion of the foil is reduced, but it is not preferable because the cube orientation becomes difficult to develop during recrystallization and the flexibility is lowered. On the other hand, if the crystal grain size before rolling is reduced, the cube orientation develops even if rolling is performed at the same degree of work. Based on the above knowledge, the present inventors have conducted experiments. As a result, the final cold rolling degree R (%) is 93.0% or more, and the average grain size GS (μm) after the final annealing is GS. It has been found that if ≦ 3.08 × R-260, the occurrence of wrinkles and wrinkles can be suppressed without impairing the flexibility. However, if R is too high, the flexibility tends to decrease. Therefore, when the copper or copper alloy foil is not preheated before use (when the method 1) is not used, R is 98% or less. Preferably there is.

As described above, the copper or copper alloy foil of the present invention needs to have excellent flexibility, and the copper or copper alloy foil needs to be bent 400,000 times or more.
Here, the number of bends is measured using an IPC (American Printed Circuit Industry Association) sliding bend tester, and the foil is in the width direction (perpendicular to the rolling direction. In the case of electrolytic foil, the MD (machine direction) A test piece cut into a strip shape of 12.5 mm and a length direction of 200 mm was used after heat treatment at 350 ° C. for 0.5 hour. The bending radius is 1.5 mm when the foil thickness is 18 μm and 1 mm when the foil thickness is 12 μm. The test piece is subjected to repeated sliding 100 times per minute, and the electrical resistance of the test piece is increased by 20% from the beginning. The number of bent times is taken as the number of end points. It has been found that a copper or copper alloy foil having a number of flexing cycles of 400,000 or more corresponds to the number of flexing cycles that are accepted by an actual double-sided CCL.
For example, even in a conventional copper foil, R (%) is 93.0% or more and the average crystal grain size GS (μm) after final annealing is GS ≦ 3.08 × R-260. Although present (eg, oxygen-free copper containing 1200 ppm Sn), it has a flexion number of less than 400,000. Further, even when using a copper foil having a known composition and having a high flexibility and produced by a known method (for example, a foil finally rolled at a working degree of 99.2%), it is 1 second at 50 ° C. to 200 ° C. What preheated for about 10 hours will satisfy | fill said Formula 6, Since it is excellent in flexibility, it is suitable for a double-sided copper clad laminated board.

Using a copper foil (copper alloy foil) having the composition shown in Table 1, double-sided CCL was produced as shown in FIG. Here, although the 1st copper foil 4 and the 2nd copper foil 6 are the same, it demonstrates distinguishing from the 1st copper foil 4 and the 2nd copper foil 6 from the order used for CCL manufacture.
In addition, as shown in Table 1, some copper foils adjusted the crystal grain size GS and the degree of processing, and performed preliminary heat treatment. The preliminary heat treatment was performed after the following chemical treatment (plating), but may be performed immediately before CCL production.

  First, one surface of the first copper foil 4 was chemically treated (plated), and a polyimide resin precursor varnish (Ube Industries U-Varnish A) was applied to this surface to a thickness of 25 μm. After that, it is dried for 30 minutes in a hot air circulation type high temperature bath set at 130 ° C., and heated up to 350 ° C. over 2000 seconds and cured (imidized) to form a resin layer 2. Produced. Next, after applying thermoplastic polyimide (adhesive layer) to the resin side of one side CCL and drying, the second copper foil 6 was stacked and thermocompression bonded with a press heated to 350 ° C. for 10 minutes to produce a double-sided CCL. . Thereafter, the double-sided CCL was cooled to room temperature, and the state of occurrence of wrinkles and wrinkles was visually determined.

[Delta] L _A is, 150 mm copper foil in the width direction, cut into strips of 12.5mm in the longitudinal direction, hit the dents scores spacing 80mm Vickers meter, to measure the coordinates of both dents, heat The distance L before applying was calculated. In addition, in the case of the copper foil sample heat-processed before lamination | stacking, the distance was calculated | required similarly after this heat processing. Next, the sample was held in a 350 ° C. oven for 30 minutes and then taken out. After cooling to room temperature, the coordinates of both dents were measured to determine the distance L ′. [Delta] L _A, respectively can be calculated as (L-L ') / L , when the contraction becomes a positive value.
Further, the Young's modulus E _A of the copper foil is determined by the oscillation method according to JIS-Z2280-1993, 0.2% yield strength YS _A was determined according to JIS-Z2241-1998 using a tensile tester.

  Flexibility was evaluated as follows. First, a copper foil was cut into a strip shape having a width direction of 12.5 mm and a length direction of 200 mm to obtain a test piece, which was used after being heated at 350 ° C. for 0.5 hours. For the bending test, an IPC (American Printed Circuit Industry Association) sliding bending tester was used, and the bending radius was 1.5 mm when the copper foil thickness was 18 μm and 1 mm when the copper foil thickness was 12 μm. Since the flexibility becomes better as the copper foil thickness becomes thinner, the bending radius may be changed depending on the copper foil thickness in order to evaluate on the same basis. Then, 100 times per minute repeated sliding was applied to the test piece, and the number of bendings where the electrical resistance of the test piece increased by 20% from the initial stage was defined as the number of end points. It has been found that a copper or copper alloy foil having a number of flexing cycles of 400,000 or more corresponds to the number of flexing cycles that are accepted by an actual double-sided CCL.

  The obtained results are shown in Table 1.

As is evident from Table 1, in the case of Examples 1 to 13 which is previously heat treated copper _{foil, | 10 × σ A | ≦} YS A next, without wrinkles or I on both sides CCL obtained, excellent flexibility It became a thing.
In the case of Examples 12 and 13 in which the rolling conditions of the copper foil were adjusted so that GS ≦ 3.08 × R-260 while R was 93.0% or more and 98.0% or less, preliminary heat treatment Even if not, | 10 × σ _A | ≦ YS _A was obtained, and the obtained double-sided CCL was free of wrinkles and creases and had excellent flexibility.

On the other hand, in the case of Comparative Examples 1 to 3 in which R was less than 93.0% and no preliminary heat treatment was performed, the flexibility decreased. In the case of Comparative Example 4 in which the electrolytic copper foil was used and no preliminary heat treatment was performed, the flexibility was lowered.
In the case of Comparative Example 5 that was annealed and rolled to obtain a GS of GS> 3.08 × R-260, and in the case of Comparative Example 6 in which R was less than 93.0%, the flexibility was lowered. .
In the case of Comparative Examples 7 to 10 where R was rolled under conditions exceeding 98.0% and no preliminary heat treatment was performed, | 10 × σ _A |> YS _A , and wrinkles and creases occurred on the obtained double-sided CCL.
In the case of Comparative Examples 11 and 12 in which the amount of the additive element (Sn or Ag) to copper exceeded 400 ppm, the flexibility decreased.

2 resin layer 2a resin composition 4 first copper or copper alloy foil 6 second copper or copper alloy foil 8 double-sided copper clad laminate

Claims (4)

Used for double-sided copper-clad laminates,
_A copper or copper alloy foil in which, when σ _A = (E _A × ΔL _A ) / 2 × 1000, | 10 × σ _A | ≦ YS _A , and the number of bendings is 400,000 or more.
However, E _A: After cooling to room temperature and held the copper or 30 minutes copper alloy foil at 350 ° C., the Young's modulus in the transverse direction of (the unit GPa), [Delta] L _A: temperature was raised to 350 ° C. from room temperature, 30 minutes held (the unit ppm, the shrinkage and positive values) the copper or the width direction dimensional change rate of the copper alloy foil when cooled to room temperature, YS _a: of the copper or copper alloy foil in a tensile test 0.2% yield strength (Unit: MPa)
Number of bendings: Using an IPC sliding bending tester, the foil was cut into strips with a width of 12.5 mm and a length of 200 mm and heat-treated at 350 ° C. for 0.5 hours. The bending radius was 18 μm. 1.5 mm in the case, and 1 mm in the case where the foil thickness is 12 μm, the test piece was subjected to repeated sliding 100 times per minute, and the number of bendings where the electrical resistance increased by 20% from the initial point was the number of times The copper or copper alloy foil is a rolled foil, the final cold rolling degree R (%) is 93.0% or more, and the average crystal grain size GS (μm) after the final annealing is GS The copper or copper alloy foil according to claim 1, wherein ≦ 3.08 × R-260. Copper or a copper alloy foil according to claim 1 or 2 [Delta] L _A is not more than 145 ppm. A first step of forming a resin layer on one side of the copper or copper alloy foil according to any one of claims 1 to 3 to obtain a single-sided copper-clad laminate, and the resin layer side of the single-sided copper-clad laminate A method for producing a double-sided copper-clad laminate, comprising a second step of laminating and heating another copper or copper alloy foil to obtain a double-sided copper-clad laminate.

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