TWI473709B - A method for manufacturing a copper-clad laminate on both sides, and a group of copper or copper alloy foils to which it is used - Google Patents

Description

Method for manufacturing two-sided copper-clad laminate, and a group of copper or copper alloy foil used therefor

The present invention relates to a method for manufacturing a double-sided copper-clad laminate which is used for a two-area layer of copper or a copper alloy foil of a resin layer for a flexible printed circuit (FPC), and a method for using the same Set of copper or copper alloy foils.

A copper clad laminate (CCL) used in a flexible wiring board (FPC), a single-sided copper clad laminate obtained by using a single-layer copper foil for a resin layer, and a two-layer copper foil on a resin layer A two-sided copper clad laminate (hereinafter referred to as "two-sided CCL"). The circuit formed on both sides of the CCL is a two-sided flexible wiring board, which is easy to realize the refinement of the circuit and the space saving of the FPC. Therefore, the use of the two-sided CCL tends to increase.

In the method for producing a double-sided CCL, there is known a method in which a varnish of a resin composition of a single side of a copper foil is cast and heat-hardened, and then another copper foil is thermocompression-bonded to the resin surface (Patent Document 1). Further, there are the following methods: a surface of the polyimide film having a thermoplastic polyimide layer on both sides and a back surface, and a thermocompression bonding copper foil; and a polyimide film having a thermoplastic polyimide layer After hot-pressing the copper foil, the thermoplastic polyimide layer is coated on the polyimide film on the opposite side of the copper foil, and the other copper foil is thermocompression bonded on the surface; and the polycrystalline silicon is cast on one side of the copper foil. The imide precursor, that is, the varnish, is hardened, and a thermoplastic polyimide layer is formed on the surface of the resin opposite to the copper foil, and the other copper foil is thermocompression bonded to the surface.

Patent Document 1: Japanese Laid-Open Patent Publication No. 05-212824

Here, when the copper foil is laminated on both surfaces of the resin layer (the above-mentioned polyimide film or the like), the copper foil (first copper foil) which is initially laminated with the resin layer is heated to 300 at the time of initial lamination. Temperature above °C and temporarily cooled. Further, when the other copper foil (second copper foil) is laminated on the opposite surface of the resin layer, the first copper foil is similarly reheated and cooled.

However, when the second copper foil is laminated and heated, it may be wrinkled or creased in parallel with the longitudinal direction of the first copper foil and generally at the center in the width direction. Even if the laminated condition of the second copper foil or the heating conditions (such as thermocompression bonding conditions, tension, etc.) at the time of lamination are adjusted, it is difficult to completely eliminate the wrinkles or creases. Further, it is considered that the wrinkles or creases are caused by the fact that the heat history of the first copper foil and the second copper foil is different, so that the second copper foil is heated and then cooled. When the temperature changes to cause the dimensional change rate of the two copper foils which are present in the resin layer to be sandwiched, the copper foil cannot withstand the stress generated thereby.

That is, the present invention has been made to solve the above problems, and an object of the invention is to provide a method for producing a double-sided copper-clad laminate which suppresses wrinkles or creases, and a copper or copper alloy foil of the same type used.

As a result of various studies conducted by the inventors of the present invention, it has been found that when a double-sided CCL is produced, even if stress is generated due to a difference in size between the two copper foils, the characteristics of the two copper foils can be adjusted so that the copper foil is not warped (bucking) ), while suppressing wrinkles or creases.

In order to achieve the above object, a method for producing a double-sided copper-clad laminate according to the present invention includes: a first step of forming a resin layer on one side of a first copper or copper alloy foil to obtain a single-sided copper-clad laminate; and a second step And heating the second copper or copper alloy foil on the resin layer side of the single-sided copper-clad laminate to obtain a double-sided copper-clad laminate; and using the first copper or copper alloy foil and the second copper or In the copper alloy foil, when the stress of the first copper or copper alloy foil is σ _A = E _A × E _B / (E _A + E _B ) × (ΔL _{A -} ΔL _B ) × 1000, the second copper or copper alloy foil The stress σ _B = E _A × E _B / (E _A + E _B ) × (ΔL _{B -} ΔL _A ) × 1000, and the negative value of σ _A and σ _B is σ _γ , 10 × σ _γ |≦YS _γ .

Wherein 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, the Young's modulus in the width direction (in units GPa); E _B : Younger modulus (in units of GPa) in the width direction when the second copper or copper alloy foil is kept at 350 ° C for 30 minutes and then cooled to room temperature; ΔL _A : heated from room temperature to 350 ° C And maintaining the dimensional change rate (in ppm) of the first copper or copper alloy foil in the width direction of the first copper or copper alloy foil after the temperature is kept at room temperature for 30 minutes and kept at 350 ° C for 30 minutes. The shrinkage is set to a positive value); ΔL _B : the dimensional change rate in the width direction of the second copper or copper alloy foil after the temperature is raised from room temperature to 350 ° C for 30 minutes and cooled to room temperature (in ppm) Positive value); YS _γ : 0.2% safety limit stress (Proof stress) in the tensile test, and if the negative value of σ _A and σ _B is A, select YS _A (unit is MPa), otherwise choose YS _B (unit: MPa); YS _A : 0.2% safety limit stress of the above first copper or copper alloy foil in tensile test; YS _B : pull The 0.2% safety limit stress of the above second copper or copper alloy foil in the tensile test.

The copper or copper alloy foil of the first aspect of the present invention is used in the method for producing the above-mentioned two-sided copper-clad laminate, and is composed of a combination of the first copper or copper alloy foil and the second copper or copper alloy foil.

In the copper or copper alloy foil of the first group of the present invention, the ΔL _{B of} the second copper or copper alloy foil is preferably 145 ppm or less.

According to the present invention, wrinkles or creases of copper or copper alloy foil can be suppressed when manufacturing a double-sided copper clad laminate.

Hereinafter, a method of manufacturing a double-sided copper-clad laminate according to an embodiment of the present invention will be described. In the present invention, the term "%" means mass% (% by mass) unless otherwise specified. Fig. 1 shows a method of manufacturing a double-sided metal-clad laminate 8.

In Fig. 1, first, the first copper foil 4 in a roll shape is continuously wound up, and a specific thickness is applied to one side of the first copper or copper alloy foil 4 to be wound up by using an application roller 10, 11, or the like. The varnish-like resin composition 2a was continuously applied. The resin composition 2a becomes the resin layer 2 after hardening. Then, the first copper or copper alloy foil 4 coated with the resin composition 2a is introduced into the drying device 15, and the resin composition 2a is cured (or semi-hardened). In this manner, a resin layer is formed on one surface of the first copper or copper alloy foil 4 to obtain a single-sided copper-clad laminate (first step). Here, the single-sided copper-clad laminate may be wound into a roll shape after completion of the first step, and the second step may be performed. In addition, when the resin layer is formed on one surface of the first copper or copper alloy foil 4, the heating is performed, and the resin composition may be used as a resin layer, for example, in addition to the resin composition. It is thermocompression bonded to one side of the first copper or copper alloy foil 4. Further, usually, the heating temperature in the first step is a temperature equal to or higher than the heating temperature in the second step. Then, the second copper or copper alloy foil 6 in the form of a roll is continuously wound up, and the first copper or copper alloy foil 4 and the second copper or copper are continuously passed between the laminating rolls 20 and 21 heated to, for example, 350 to 400 °C. Alloy foil 6. 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 into a roll.

Further, as shown in FIG. 2, the double-sided copper-clad laminate 8 is formed 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, refined copper (JIS-1100), and oxygen-free copper (JIS-1020), or pure copper or refined copper. A total of 40 to 2000 ppm by mass of Sn and/or Ag is added to the oxygen-free copper. Here, when the composition of both the first copper or copper alloy 4 and the second copper or copper alloy 6 contains a total of more than 400 ppm of Sn and/or Ag, it cannot be used for applications requiring bending properties, but When any of the foils 4 and 6 contains a total of more than 400 ppm of Sn and/or Ag, the foil is removed from both sides of the CCL by etching, and the other foil remains without deterioration of the bendability. The thickness 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 composition of the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 may be different, but the same composition is usually used. The first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 may be rolled foil or electrolytic foil.

As the resin layer 2, a thermosetting resin such as polyimine, PET (polyethylene terephthalate), an epoxy resin, or a phenol resin; a thermoplastic resin such as a saturated polyester resin can be used, but it is not limited to these resins. Further, a varnish in which a component of the resin layer is dissolved in a solvent (for example, a polyamidic acid solution of a polyimide precursor) may be applied to one surface of the first copper or copper alloy foil 4 and heated. Thereby, the solvent is removed, and the reaction (for example, hydrazine imidization reaction) is carried out to harden it. The thickness of the resin layer 2 can be, for example, about 1 to 15 μm.

Next, the characteristics of the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 which are characteristic parts of the present invention will be described.

Hereinafter, when a resin layer is formed on one surface of the first copper or copper alloy foil 4, and the second copper or copper alloy foil 6 is laminated to produce a double-sided CCL, two pieces of copper or copper alloy foil 4 sandwiching the resin are used. The stress caused by the difference in the dimensional change of 6.

First, at the temperature T ₁ (T ₁ is the product of the second layer of copper or copper alloy foil heating the 6 temperature) laminated to both surfaces CCL Upon cooling to the case of T up of _2, a first copper or copper alloy foil 4 The applied stress σ _A is expressed by the following formula 1:

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). Further, the dimensional change Δ is a change in the shrinkage and is a change in the width direction (the direction of the roll width when the CCL is continuously produced from the roll of copper or copper alloy foil).

Here, since the copper or copper alloy foil used for CCL is similar to pure copper, the thermal expansion coefficient α can be obtained even if the additive component is slightly contained (subscripts A and B respectively indicate the first copper or copper alloy foil 4, and the second Copper or copper alloy foil 6) is considered to be the same (α _A ≒ α _B ). Therefore, Formula 1 is expressed by the following Formula 2:

σ _A = E _A × E _B / (E _A + E _B ) × (ΔL _{A -} ΔL _B ) × 1000 (2).

Here, 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 in the first heating course, the first copper Or the Young's modulus of the copper alloy foil in the width direction (unit: GPa); E _B : produced by the second heat history of holding the second copper or copper alloy foil at 350 ° C for 30 minutes and cooling to room temperature The Young's modulus of the second copper or copper alloy foil in the width direction (unit: GPa); ΔL _A : based on the temperature from room temperature to 350 ° C for 30 minutes and then cooled to room temperature, again at 350 The dimensional change rate in the width direction of the first copper or copper alloy foil after the temperature is kept at room temperature for 30 minutes and cooled to room temperature (in ppm, the shrinkage is set to a positive value); ΔL _B : the temperature is raised from room temperature to 350 ° C, The dimensional change rate (unit: ppm, and shrinkage was set to a positive value) in the width direction of the second copper or copper alloy foil after holding for 30 minutes and cooling to room temperature.

Further, the room temperature is 25 to 35 ° C (usually 25 ° C).

That is, when the Young's modulus of the two copper or copper alloy foils 4 and 6 is made small, and the difference in the dimensional change rate (ΔL _{A -} ΔL _B ) between the copper or copper alloy foils 4 and 6 is made small, the stress σ _A is small, and it is not easy to produce wrinkles or creases when manufacturing CCL on both sides.

Here, even if the two copper or copper alloy foils 4, 6 are the same, the difference in dimensional change rate (ΔL _{A -} ΔL _B ) occurs, so that it is apparent that the difference is not caused by thermal expansion. Further, if the metal is heated, a change in structure such as recrystallization or recovery occurs. Therefore, if the metal is heated and then cooled, it becomes shorter (heat shrinkage) or longer (thermal elongation) than the original size. Further, even if the temporarily heated and cooled metal is heated and cooled again at the same temperature or lower, heat shrinkage or thermal elongation does not occur. Furthermore, these phenomena are generated in both the rolled foil and the electrolytic foil, but the strain caused by the calendering of the rolled foil is larger, and, depending on the composition of the foil, the calendering due to the heat applied during the manufacture of the CCL The tissue changes to a recrystallized structure, so the heat shrinkage or thermal elongation becomes large.

Fig. 3 shows a state in which the above-described heat extension or heat shrinkage occurs by the heat applied when the CCL is produced, resulting in wrinkles (creases) 100 in the first copper or copper alloy foil 4.

First, when the single-sided copper-clad laminate is produced in the first step, the first copper or copper alloy foil 4 is heated and then cooled, and the heat shrinkage is smaller than the original length. Then, when the double-sided copper-clad laminate is produced in the second step, the second copper or copper alloy foil 6 is heated and then cooled, and is intended to be heat-shrinked to be smaller than the original length (arrow in Fig. 3). On the other hand, the first copper or copper alloy foil 4 which has been heat-shrinked in the first step hardly undergoes heat shrinkage in the second step (arrow in Fig. 3).

Therefore, at the time of cooling after heating in the second step, compressive stress is applied to the first copper or copper alloy foil 4 by the force of the second copper or copper alloy foil 6 to be contracted. Then, the first copper or copper alloy foil 4 cannot withstand the compressive stress and warp (wrinkles or creases).

However, when compressive stress is applied to the side of the first copper or copper alloy foil 4, if the safety limit stress of the copper foil is greater than the compressive stress (σ _{A of the} formula 2), warpage is not caused, and wrinkles are hard to occur. Pleats or creases. It is generally impossible to determine the safety limit stress of the copper foil with respect to compression, but whether the boundary value causing the warpage can be replaced by the safety limit stress (YS) with respect to the stretching. In other words, it is considered that wrinkles or creases do not occur when the first copper or copper alloy foil 4 is selected such that YS becomes σ _A or more.

Further, the inventors of the present invention obtained the conditions for producing wrinkles or creases in the production of the double-sided copper-clad laminate by experiments, and as a result, it was found that the σ _A was obtained with respect to Formula 2

|10×σ _A |≦YS _A (3)

When the first copper or copper alloy foil 4 is selected, wrinkles or creases are less likely to occur.

On the other hand, when the compressive stress is applied to the second copper or copper alloy foil 6, it is known that it becomes σ _B with respect to Formula 2

|10×σ _B |≦YS _B (4)

When the second copper or copper alloy foil 6 is selected, wrinkles or creases are less likely to occur. However, compressive stress is generally applied to the first copper or copper alloy foil 4.

In order to satisfy the formula 3 (or the formula 4), σ _A (σ _B ), that is, the difference in the dimensional change rate (ΔL _{A -} ΔL _B ) is preferably as small as possible, so that the first copper or copper alloy foil 4 is subjected to the first step. The difference between the heat and the heat received by the second copper or copper alloy foil 6 in the second step is preferably as small as possible. Moreover, the smaller the strain applied to the first copper or copper alloy foil 4 in the first step, the smaller the dimensional change rate (ΔL _{A -} ΔL _B ).

As described above, specific methods for satisfying Expressions 3 and 4 include: 1) preheating the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6; and 2) the first copper or copper alloy foil. 4 and when the second copper or copper alloy foil 6 is a rolled foil, it is calendered with a low degree of work; 3) the pressure delay tension set according to the thickness and mechanical properties of the foil does not exceed the limit; 4) the first copper or An electrolytic foil is used for the copper alloy foil 4 and the second copper or copper alloy foil 6. However, in consideration of the fact that compressive stress is generally applied to the first copper or copper alloy foil 4 side, the method of 1) to 4) may be applied only to the second copper or copper alloy foil 6.

Regarding the method of the above 1), it is known that pure copper is a metal having a face-centered cubic structure, and if recrystallization is performed by heating, the cube orientation is expanded and the flexibility is improved. The copper modulus of the cube-azimuth extended copper foil is lower, and the 0.2% safety limit stress in the tensile test is also lower. That is, it can be said that such a cubic azimuth-expanding copper foil is most likely to be creased or wrinkled when the two-side CCL is produced (when the second step is performed). According to experiments by the inventors of the present invention, for example, the pure copper foil was kept at 350 ° C for 30 minutes and then cooled. As a result, the Young's modulus was about 70 GPa, and the 0.2% safety limit stress was about 50 MPa. In this way, it is considered that even if the copper or copper alloy foil having a small safety limit stress is heated again to about 350 ° C and then cooled, the dimensional change is almost zero.

Therefore, the same as the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 (E _A ≒ E _B , |σ _A |≒|σ _B |), when ΔL _A ≒ 0, Equation 2 It is expressed by the following formula 5:

σ _A = (E _A × ΔL _B ) / 2 × 1000 (5).

Further, according to Equations 3 and 5, Equation 6 is obtained as follows:

|10000×(E _A ×ΔL _B /2)|≦YS _A (6),

According to the above experimental results, when E _A = 70 GPa and YS _A = 50 MPa were substituted into Formula 5, ΔL _B = 143 (ppm) was obtained. In other words, when at least the second copper or copper alloy foil 6 is heated before use, ΔL _B ≦ 143 (ppm) is used, and both of them have flexibility and are less likely to cause creases or wrinkles. The heating condition of the second copper or copper alloy foil 6 may be heated at 50 to 200 ° C for about 1 to 10 hours, but is not limited thereto. For example, the heating conditions may be maintained at 60 ° C for 3 hours or at 130 ° C for 3 seconds. Of course, if a copper foil with a high safety limit of 0.2% is used, L _B may also exceed 143 ppm, but if both the first copper or copper alloy foil 4 and the second copper or copper alloy foil 6 use a 0.2% safety limit. In the case of a copper foil having a high stress, flexibility cannot be obtained. Therefore, it is preferable to use ΔL _B ≦ 143 (ppm) on the side of the second copper or copper alloy foil 6 .

Next, in the method of the above 2), the strain of the rolled foil changes depending on the degree of rolling work after the final annealing, the amount of rolling reduction, the tension, the processing temperature, and the like. However, the amount of shrinkage or tension may be difficult to specify in the same manner depending on the thickness of the foil of the object to be processed or the performance of the calender. Further, the higher the processing temperature, the smaller the strain, but the rolling oil in the rolling acts as a coolant, and it is difficult to specify the instantaneous processing temperature.

Therefore, the conditions required for the foil are specified in accordance with the degree of calendering. Here, if the degree of rolling is reduced, the strain of the foil becomes small, but when the crystal is recrystallized, it is difficult to expand the cube orientation and the bendability is lowered, which is not preferable. On the other hand, when the crystal grain size before rolling is reduced, even if rolling is performed at the same degree of work, the cube orientation is expanded. According to the above findings, the inventors of the present invention conducted experiments and found out that if the final cold rolling degree R (%) is 93.0 ≦R, and the average crystal grain size GS (μm) after final annealing is GS ≦ 3.08 × R -260, does not impair the bendability, and can suppress the occurrence of creases or wrinkles. Further, when the two-sided CCL is used for the bent portion, the copper foil of either one (the one having poor flexibility) is removed by etching, and only the curved portion is a single-sided CCL, so that the first copper or copper alloy foil 4 and Any one of the second copper or copper alloy foils 6 may satisfy the above formula (GS ≦ 3.08 × R - 260).

Further, in the above formulas 1 to 3, when the compressive stress is generated on the side of the first copper or copper alloy foil 4, the first copper or copper alloy foil and the second copper or copper alloy foil are usually selected in the following manner: 1 Stress of copper or copper alloy foil σ _A = E _A × E _B / (E _A + E _B ) × (ΔL _{A -} ΔL _B ), stress of the second copper or copper alloy foil σ _B = E _A × E _B /(E _A + E _B ) × (ΔL _{B -} ΔL _A ), and when the negative values of σ _A and σ _B are σ _γ , |10 × σ _γ | ≦ YS _γ .

Where YS _γ : 0.2% safety limit stress in the tensile test, and if the negative value of σ _A and σ _B is A, YS _A (unit is MPa) is selected, and YS _B (unit is MPa) is selected instead. ;YS _A : 0.2% safety limit stress of the above first copper or copper alloy foil in the tensile test; YS _B : 0.2% safety limit stress of the above second copper or copper alloy foil in the tensile test.

Example

The first copper foil 4 and the second copper foil 6 having the composition shown in Table 1 were combined to produce a double-sided CCL as shown in Fig. 1 . Here, in Experimental Examples 1 to 3, 10 and Comparative Examples 1 and 2, the first copper foil 4 was the same as the second copper foil 6. In the other experimental examples and comparative examples, the first copper foil 4 and the second copper foil 6 were each made of a different copper foil. Further, in Table 1, in Experimental Example 6, compressive stress was applied to the second copper foil 6 side, and σ _B became a negative value, so σ _B became σ _γ , and the magnitude between |10 × σ _γ | and YS _γ was evaluated. . In the other experimental examples and comparative examples, compressive stress was applied to the first copper foil 4, and σ _A became a negative value. Therefore, σ _{A was} σ _γ , and the magnitude between |10 × σ _γ | and YS _γ was evaluated.

Further, a part of the copper foil was adjusted to have an average crystal grain size GS and a workability R as shown in Table 1, or a preliminary heat treatment was performed. Further, the pre-heat treatment is performed after the following chemical treatment (electroplating), or may be performed after the final rolling, or may be performed before the CCL is to be produced.

First, the single surface of the first copper foil 4 was chemically treated (electroplated), and the polyimide varnish (U-Varnish A manufactured by Ube Industries, Ltd.) was applied to the surface at a thickness of 25 μm. Then, it was dried in a hot air circulation type high temperature bath set to 130 ° C for 30 minutes, and the temperature was raised to 350 ° C for 2,000 sec and hardened (imidization) to form the resin layer 2, thereby producing a single-sided CCL. Then, after coating and drying the thermoplastic polyimide on the side of the resin of the single-sided CCL, the second copper foil 6 was overlaid, and thermocompression bonding was performed for 10 minutes by a press heated to 350 ° C to produce a two-sided CCL. . Then, the two-sided CCL was cooled to room temperature, and the occurrence of creases or wrinkles was visually determined.

In the ΔL _A and the ΔL _B , the first copper foil 4 and the second copper foil 6 were each cut into a strip shape having a width of 150 mm and a longitudinal direction of 12.5 mm, and a dent having a score of 80 mm was measured by a Vickers hardness tester. The coordinates of the two dimples are used to determine the distance L before heating. Further, in the case of a copper foil sample which is previously heat-treated before the lamination, the distance is similarly obtained after the heat treatment. Then, the sample was taken in an oven at 350 ° C for 30 minutes, taken out, cooled to room temperature, and then the coordinates of the two dents were measured to determine the distance L'. ΔL _A and ΔL _B can be calculated as (L-L')/L, respectively, and the case of shrinkage is a positive value. Further, according to the definitions of ΔL _A and ΔL _B , ΔL _A is temporarily heated from room temperature to 350 ° C for 30 minutes, and then cooled to room temperature, the size is set to L, and the coordinates of the two dents when reheating are set. For L'.

Further, the Young's modulus E _A and E _B of the first copper foil 4 and the second copper foil 6 are obtained by the vibration method according to JIS-Z2280-1993, and the 0.2% safety limit stress YS _A and YS _B are stretched. The experimental machine was obtained in accordance with JIS-Z2241-1998.

The flexibility was evaluated in the following manner. First, any one of the first copper foil 4 or the second copper foil 6 is removed by a known photolithography technique, and a wiring having a circuit width of 200 μm is formed on the other copper foil, and thermocompression bonding is applied to the wiring. A polyimine film made of an epoxy-based adhesive was used as a coating layer to prepare an FPC for bending test. At this time, the thickness of the resin layer 2 was set to 15 μm, the cover layer was set to 12.5 μm, and the thickness of the adhesive layer on the copper foil was set to 2.5 μm. In the case where the double-sided CCL is used for the bent portion, the copper foil of either one (the one having poor flexibility) is removed by etching, and only the curved portion is a single-sided CCL, so that the first copper foil 4 or the second copper strip is removed. Test in one of the copper foils 6.

In the bending test, an IPC (American Printed Circuit Industry Association) sliding bending tester was used, and the bending radius was set to 1.5 mm when the thickness of the copper foil was 18 μm, and was set to 1 mm when the thickness of the copper foil was 12 μm. The thinner the thickness of the copper foil, the better the bendability. Therefore, the evaluation is performed on the same basis, and the bending radius may be changed according to the thickness of the copper foil. Then, the FPC test piece load was repeatedly slid 100 times per minute, and the number of bends of the resistance of the wiring from the initial rise of 10% was ended. Here, when the number of times of bending exceeds 100,000 times, it is set to be good (○), less than 50,000 times is set to be poor (×), and 50,000 times or more and less than 100,000 times are judged to be bendable. Conditions are used (△).

The results obtained are shown in Table 1. In addition, in Table 1, "the bending property of the first copper foil of the experimental example 1 is ○", and the evaluation was performed when the second copper foil was removed from the CCL on both surfaces of Experimental Example 1 by etching, and the first copper foil remained.

As shown in Table 1, in the case of Examples 1 and 2 in which the first copper foil 4 and the second copper foil 6 were previously heat-treated, |10 × σ _γ | ≦YS _γ was obtained, and the obtained two-sided CCL was obtained. No wrinkles or creases, and excellent flexibility.

Moreover, when the rolling conditions of the first copper foil 4 and the second copper foil 6 of the rolled foil were adjusted to have R of 93.0% or more and the case of the experimental example 3 of GS ≦ 3.08 × R-260, it was also |10. ×σ _γ |≦YS _γ , the obtained two-sided CCL has no wrinkles or creases, and is excellent in flexibility.

On the other hand, in the case of the experimental examples 4 to 9 in which the first copper foil 4 and the second copper foil 6 were different from each other, the film also became |10 × σ _γ | ≦ YS _γ , and the obtained two-sided CCL was absent. Wrinkles or creases. However, the flexibility is different depending on which of the first copper foil 4 and the second copper foil 6 remains. For example, in the case of the second copper foil 6 of Experimental Example 6 and the first copper foil 4 of Experimental Example 7, the amount of addition of Sn is large (2000 ppm), and the flexibility is poor. In the case of the first copper foil 4 of Experimental Example 8 and the second copper foil 6 of Experimental Example 9, the electrolytic copper foil was not previously heat-treated and used, and the flexibility was inferior.

Further, in the case of the experimental example 10 in which the same copper foil was used for the first copper foil 4 and the second copper foil 6, it was also |10 × σ _γ | ≦ YS _γ , and the obtained two-sided CCL was free from wrinkles or creases. . However, both of the foils have a GS>3.08×R-260, so the bendability is Δ in the case where any of the foils remains.

In the case of Comparative Examples 1 and 2, the combination of the foils was not suitable, so that |10 × σ _γ | > YS _γ was produced, and wrinkles or creases were formed in the obtained two-sided CCL.

In the case where the refined copper which is a commercial product is used in the first comparative example 3 of the first copper foil 4 and the second copper foil 6, the rolling condition is GS>3.08×R-260, and therefore the bending property is inferior.

2. . . Resin layer

2a. . . Resin composition

4. . . 1st copper or copper alloy foil

6. . . 2nd copper or copper alloy foil

8. . . Two-sided copper clad laminate

10, 11. . . Application roller

15. . . Drying device

20, 21. . . Laminating roll

100. . . Wrinkle

Fig. 1 is a view showing a method of manufacturing a double-sided copper-clad laminate according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a configuration example of a double-sided copper clad laminate.

Fig. 3 is a view showing a state in which wrinkles (creases) occur in the first copper or copper alloy foil due to heat applied during the production of the double-sided copper clad laminate.

2. . . Resin layer

2a. . . Resin composition

4. . . 1st copper or copper alloy foil

6. . . 2nd copper or copper alloy foil

8. . . Two-sided copper clad laminate

10, 11. . . Application roller

15. . . Drying device

20, 21. . . Laminating roll

Claims (3)

A method for producing a double-sided copper-clad laminate, comprising: a first step of forming a resin layer on one side of a first copper or copper alloy foil to obtain a single-sided copper-clad laminate; and a second step The second copper or copper alloy foil is laminated on the resin layer side of the single-sided copper-clad laminate to obtain a double-sided copper-clad laminate; and the first copper or copper alloy foil and the second copper or copper are used In the alloy foil, when the stress of the first copper or copper alloy foil is σ _A = E _A × E _B / (E _A + E _B ) × (ΔL _{A -} ΔL _B ) × 1000, the second copper or copper alloy foil When the stress σ _B = E _A × E _B / (E _A + E _B ) × (ΔL _{B -} ΔL _A ) × 1000, and the negative value of σ _A and σ _B is σ _γ , |10 × σ _γ |≦YS _γ , wherein 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 in the width direction Young's modulus (in GPa); E _B : Younger modulus (in GPa) in the width direction when the second copper or copper alloy foil is kept at 350 ° C for 30 minutes and then cooled to room temperature; ΔL _A : Cooling from room temperature to 350 ° C and holding for 30 minutes The dimensional change rate (in ppm, the shrinkage is set to a positive value) in the width direction of the first copper or copper alloy foil after the temperature at room temperature is maintained at 350 ° C for 30 minutes and cooled to room temperature. ; ΔL _B : dimensional change rate in the width direction of the second copper or copper alloy foil after heating from room temperature to 350 ° C for 30 minutes and cooling to room temperature (in ppm, the shrinkage is set to a positive value); YS _γ : 0.2% safety stress (Proof stress) in the tensile test, and if the negative value of σ _A and σ _B is A, then YS _A (unit is MPa) is selected, and YS _B (unit is selected instead) MPa); YS _A : 0.2% safety limit stress of the first copper or copper alloy foil in the tensile test; YS _B : 0.2% safety limit stress of the second copper or copper alloy foil in the tensile test. A group of copper or copper alloy foils for use in a method for producing a two-sided copper clad laminate according to claim 1 and comprising a combination of the first copper or copper alloy foil and the second copper or copper alloy foil Composition. A copper or copper alloy foil according to claim 2, wherein the second copper or copper alloy foil has a ΔL _B of 145 ppm or less.