Material for printed circuit board, metal laminate, methods for producing them, and method for producing printed circuit board

1. A method for producing a material for a printed circuit board, comprising:

subjecting a film (A) provided with a fluorinated resin layer comprising a composition comprising a fluorinated copolymer (a) to a heat treatment to obtain a material for a printed circuit board, wherein

the film (A) is a film (A1) consisting of the fluorinated resin layer or an adhesive film (A2) having the fluorinated resin layer directly laminated on at least one side of a heat resistant resin film,

the fluorinated copolymer (a) has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group and an isocyanate group, has a melting point of from 280 to 320° C., and has a melt flow rate of at least 2 g/10 min measured at 372° C. under a load of 49N, and

the heat treatment of the film (A) is carried out at a temperature of at least 250° C. and lower by at least 5° C. than the melting point of the fluorinated copolymer (a) so that the ratio of the following melt flow rate (II) (MFR(II)) to the following melt flow rate (I) (MFR(I)) [MFR(II)/MFR(I)] is from 0.05 to 0.5 and that the following MFR(II) is at most 15 g/10 min, wherein,

MFR(I): the melt flow rate of the fluorinated resin layer before the heat treatment measured at 372° C. under a load of 49N; and

MFR(II): the melt flow rate of the fluorinated resin layer after the heat treatment measured at 372° C. under a load of 49N.

2. The method for producing a material for a printed circuit board according to claim 1 , wherein the fluorinated copolymer (a) has at least a carbonyl group-containing group as the functional group, and the carbonyl group-containing group is at least one selected from the group consisting of a group having a carbonyl group between carbon atoms in a hydrocarbon group, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group and an acid anhydride residue.

3. The method for producing a material for a printed circuit board according to claim 1 , wherein the content of the functional group is from 10 to 60,000 groups per 1×10 6 carbon atoms in the main chain of the fluorinated copolymer (a).

4. A method for producing a metal laminate, comprising:

producing a material for a printed circuit board by the method according to claim 1 ; and

directly laminating a metal layer on the fluororesin layer of the material for a printed circuit board.

5. A method for producing a printed circuit board, comprising:

producing a metal laminate by the method according to claim 4 ; and

etching the metal layer to form a patterned circuit.

6. The method for producing a printed circuit board according to claim 5 , wherein the formed patterned circuit is soldered by a soldering iron.

7. A method for producing a metal laminate, comprising:

subjecting a metal laminate precursor comprising an adhesive film (A2) having a fluorinated resin layer comprising a composition comprising a fluorinated copolymer (a) directly laminated on at least one side of a heat resistant resin film, and a metal layer directly laminated on the at least one fluorinated resin layer, to a heat treatment to obtain a metal laminate, wherein

the fluorinated copolymer (a) has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group and an isocyanate group, has a melting point of from 280 to 320° C., and has a melt flow rate of at least 2 g/10 min measured at 372° C. under a load of 49N, and

the heat treatment is carried out at a temperature of at least 250° C. and lower by at least 5° C. than the melting point of the fluorinated copolymer (a) so that the ratio of the following melt flow rate (VI) (MFR(VI)) to the following melt flow rate (V) (MFR(V)) [MFR(VI)/MFR(V)] is from 0.05 to 0.5 and that the following MFR(VI) is at most 15 g/10 min, wherein,

MFR(V): the melt flow rate of the fluorinated resin layer before the heat treatment measured at 372° C. under a load of 49N; and

MFR(VI): the melt flow rate of the fluorinated resin layer after the heat treatment measured at 372° C. under a load of 49N.

8. The method for producing a metal laminate according to claim 7 , wherein the fluorinated copolymer (a) has at least a carbonyl group-containing group as the functional group, and the carbonyl group-containing group is at least one selected from the group consisting of a group having a carbonyl group between carbon atoms in a hydrocarbon group, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group and an acid anhydride residue.

9. The method for producing a metal laminate according to claim 7 , wherein the content of the functional group is from 10 to 60,000 groups per 1×10 6 carbon atoms in the main chain of the fluorinated copolymer (a).

10. The method for producing a metal laminate according to claim 7 , wherein the fluorinated resin layer has a thickness of from 1 to 20 μm.

11. A method for producing a printed circuit board, comprising:

producing a metal laminate by the method according to claim 7 ; and

etching the metal layer to form a patterned circuit.

12. The method for producing a printed circuit board according to claim 11 , wherein the patterned circuit is soldered by a soldering iron.