Copper foil composite, formed product and method of producing the same

1. A copper foil composite comprising a copper foil and a resin layer laminated thereon, satisfying an equation 1: (f 3 ×t 3 )/(f 2 ×t 2 )≥1 wherein t 2 is a thickness of the copper foil measured in mm, f 2 is a stress of the copper foil measured in MPa under tensile strain of 4%, t 3 is a thickness of the resin layer measured in mm, f 3 is a stress of the resin layer measured in MPa under tensile strain of 4% measure and an equation 2: 1≤33f 1 /(F×T) wherein f 1 is 180° peeling strength between the copper foil and the resin layer measured in N/mm, F is strength of the copper foil composite measured in MPa under tensile strain of 30%, and T is a thickness of the copper foil composite measured in mm, wherein a Cr oxide layer is formed at a coating amount of 5 to 100 μg/dm 2 on a surface of the copper foil on which the resin layer is not laminated, and further wherein the 180° peeling strength is measured by conducting a 180° peel test as the surface of the copper foil in a composite test specimen is fixed on a SUS plate and the resin layer is peeled in a direction at an angle of 180° in accordance with JIS-05016.

2. The copper foil composite according to claim 1 , wherein a Ni layer or a Ni alloy layer having a thickness of 0.001 to 5.0 μm is formed between the Cr oxide layer and the copper foil.

3. The copper foil composite according to claim 2 , wherein the thickness of the Ni layer or the Ni alloy layer is 0.001 to 0.10 μm.

4. The copper foil composite according to claim 3 , wherein the equations 1 and 2 are true at the temperature lower than the glass transition temperature of the resin layer.

5. The copper foil composite according to claim 3 , wherein a ratio I/L of fracture strain I of the copper foil composite to fracture strain L of the resin layer alone is 0.7 to 1.

6. A formed product obtained by working the copper foil composite according to claim 3 .

7. A method of producing a formed product comprising working the copper foil composite according to claim 3 .

8. The copper foil composite according to claim 2 , wherein the equations 1 and 2 are true at the temperature lower than the glass transition temperature of the resin layer.

9. The copper foil composite according to claim 2 , wherein a ratio I/L of fracture strain I of the copper foil composite to fracture strain L of the resin layer alone is 0.7 to 1.

10. A formed product obtained by working the copper foil composite according to claim 2 .

11. A method of producing a formed product comprising working the copper foil composite according to claim 2 .

12. The copper foil composite according to claim 1 , wherein the equations 1 and 2 are true at the temperature lower than the glass transition temperature of the resin layer.

13. The copper foil composite according to claim 12 , wherein a ratio I/L of fracture strain I of the copper foil composite to fracture strain L of the resin layer alone is 0.7 to 1.

14. A formed product obtained by working the copper foil composite according to claim 12 .

15. A method of producing a formed product comprising working the copper foil composite according to claim 12 .

16. The copper foil composite according to claim 1 , wherein a ratio I/L of fracture strain I of the copper foil composite to fracture strain L of the resin layer alone is 0.7 to 1.

17. A formed product obtained by working the copper foil composite according to claim 16 .

18. A method of producing a formed product comprising working the copper foil composite according to claim 16 .

19. A formed product obtained by working the copper foil composite according to claim 1 .

20. A method of producing a formed product comprising working the copper foil composite according to claim 1 .