Method for forming conductor layer, and method for producing multilayer wiring substrate using same
A method for forming a conductor layer, including subjecting a surface of a polyimide film where a polyimide layer (a) is formed to polyimide etching treatment, to remove at least part of the polyimide layer (a), the polyimide film having the polyimide layer (a) formed on one surface or both surfaces of a polyimide layer (b); and then forming a conductor layer on the surface, such that the polyimide etching treatment time T (min), which is represented using t (min) defined by the formula as described below, is within the range of 0.2t≤T≤5t. t ( min ) = Thickness of polyimide layer ( a ) ( µm ) Etching rate in the direction of thickness of polyimide layer ( a ) (µm/min)
1. A method for forming a conductor layer, comprising:
providing a polyimide film consisting of a polyimide layer (b) and a polyimide layer (a) formed on one or both surfaces of the polyimide layer (b);
contacting the polyimide layer (a) of the polyimide film with a polyimide etching solution, so that the etching starts from the surface of the polyimide layer (a) to remove at least part of the polyimide layer (a); and then
forming a conductor layer on the surface of the etched polyimide film;
wherein the polyimide etching treatment time T (min), which is represented using t (min) defined by the formula as described below, is within the range of 0.2t<T<5t
t
(
min
)
=
Thickness
of
polyimide
layer
(
a
)
(
µm
)
Etching
rate
in
the
direction
of
thickness
of
polyimide
layer
(
a
)
(µm/min)
and wherein the polyimide etching solution etches the polyimide layer (a) faster than the polyimide layer (b).
2. The method for forming a conductor layer according to claim 1 , wherein
the polyimide layer (b) consists essentially of a polyimide obtained using a 3,3′,4,4′-biphenyltetracarboxylic acid compound in an amount of 90 mol % or more as the tetracarboxylic acid component, and 4,4′-diaminodiphenyl ether and/or p-phenylenediamine in an amount of 90 mol % or more as the diamine component, and
the polyimide layer (a) consists essentially of a polyimide obtained using a 3,3′,4,4′-biphenyltetracarboxylic acid compound, a 2,3,3′,4′-biphenyltetracarboxylic acid compound, a pyromellitic acid compound, or a plurality of compounds selected from these compounds as the tetracarboxylic acid component, and p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl methane, 2,2-bis(4-aminophenyl)propane, 1,3-bis(4-aminophenoxy benzene), 1,4-bis(4-aminophenoxy)benzene, 4,4′-bis(4-aminophenyl)diphenyl ether, 4,4′-bis(4-aminophenyl)diphenyl methane, 4,4′-bis(4-aminophenoxy)diphenyl ether, 4,4′-bis(4-aminophenoxy)diphenyl methane, 2,2-bis[4-(aminophenoxy)phenyl]propane, or a plurality of compounds selected from these compounds as the diamine component, with the proviso that a polyimide obtained using 3,3′,4,4′-biphenyltetracarboxylic acid compound in an amount of 90 mol % or more as the tetracarboxylic acid component, and 4,4′-diaminodiphenyl ether and/or p-phenylenediamine in an amount of 90 mol % or more as the diamine component is excluded.
3. The method for forming a conductor layer according to claim 1 , wherein the polyimide layer (a) consists of polyimide obtained from a polyimide precursor composition comprising any one or more of an aminosilane compound, an epoxysilane compound, an aluminum compound, or a titanate compound.
4. The method for forming a conductor layer according to claim 1 , wherein the thickness of the polyimide layer (b) is 1 μm to 100 μm, and the thickness of the polyimide layer (a) is 0.05 μm to 5 μm.
5. The method for forming a conductor layer according to claim 1 , wherein the polyimide film is a polyimide film obtained by
applying a polyimide precursor solution, which is to be formed into the polyimide layer (a), to at least one surface of a self-supporting film obtained from a polyimide precursor solution, which is to be formed into the polyimide layer (b); and then
subjecting the film to heat treatment at a temperature of 350° C. to 600° C.
6. The method for forming a conductor layer according to claim 1 , wherein the polyimide etching treatment is wet etching treatment with a polyimide etching solution, or dry etching treatment by plasma treatment.
7. The method for forming a conductor layer according to claim 1 , wherein a metal film layer as the conductor layer is formed on the surface of the polyimide film by electroless plating.
8. A method for producing a multilayer wiring substrate, comprising:
providing a polyimide film consisting of a polyimide layer (b) and a polyimide layer (a) formed on one or both surfaces of the polyimide layer (b);
laminating the polyimide film onto a printed wiring board in which a conductor wiring pattern is formed on an insulation substrate, so that the polyimide layer (a) is exposed at a surface of the polyimide film which is not in contact with the printed wiring board;
forming a via to the conductor wiring pattern from the surface of the polyimide film;
performing a desmear treatment by contacting the polyimide layer (a) of the polyimide film with a polyimide etching solution, so that the etching starts from the surface of the polyimide layer (a) to remove at least a part of the polyimide layer (a); and then
forming a conductor layer on all or part of the surface of the etched polyimide film and within the via;
wherein the desmear treatment time T (min), which is represented using t (min) defined by the formula as described below, is within the range of 0.2t<T<5t, and is the time at which the desmearing is completed
t
(
min
)
=
Thickness
of
polyimide
layer
(
a
)
(
µm
)
Etching
rate
in
the
direction
of
thickness
of
polyimide
layer
(
a
)
(µm/min)
and wherein the polyimide etching solution etches the polyimide layer (a) taster than the polyimide layer (b).
9. The method for producing a multilayer wiring substrate according to claim 8 , wherein
the polyimide layer (b) consists essentially of a polyimide obtained using a 3,3′,4,4′-biphenyltetracarboxylic acid compound in an amount of 90 mol % or more as the tetracarboxylic acid component, and 4,4′-diaminodiphenyl ether and/or p-phenylenediamine in an amount of 90 mol % or more as the diamine component, and
the polyimide layer (a) consists essentially of a polyimide obtained using a 3,3′,4,4′-biphenyltetracarboxylic acid compound, a 2,3,3′,4′-biphenyltetracarboxylic acid compound, a pyromellitic acid compound, or a plurality of compounds selected from these compounds as the tetracarboxylic acid component, and p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl methane, 2,2-bis(4-aminophenyl)propane, 1,3-bis(4-aminophenoxy benzene), 1,4-bis(4-aminophenoxy)benzene, 4,4′-bis(4-aminophenyl)diphenyl ether, 4,4′-bis(4-aminophenyl)diphenyl methane, 4,4′-bis(4-aminophenoxy)diphenyl ether, 4,4′-bis(4-aminophenoxy)diphenyl methane, 2,2-bis[4-(aminophenoxy)phenyl]propane, or a plurality of compounds selected from these compounds as the diamine component, with the proviso that polyimide obtained using 3,3′,4,4′-biphenyltetracarboxylic acid compound in an amount of 90 mol % or more as the tetracarboxylic acid component, and 4,4′-diaminodiphenyl ether and/or p-phenylenediamine in an amount of 90 mol % or more as the diamine component is excluded.
10. The method for producing a multilayer wiring substrate according to claim 8 , wherein the polyimide layer (a) consists of polyimide obtained from a polyimide precursor composition comprising any one or more of an aminosilane compound, an epoxysilane compound, an aluminum compound, or a titanate compound.
11. The method for producing a multilayer wiring substrate according to claim 8 , wherein the thickness of the polyimide layer (b) is 1 μm to 100 μm, and the thickness of the polyimide layer (a) is 0.05 μm to 5 μm.
12. The method for producing a multilayer wiring substrate according to claim 8 , wherein the polyimide film is a polyimide film obtained by
applying a polyimide precursor solution, which is to be formed into the polyimide layer (a), to at least one surface of a self-supporting film obtained from a polyimide precursor solution, which is to be formed into the polyimide layer (b); and then
subjecting the film to heat treatment at a temperature of 350° C. to 600° C.
13. The method for producing a multilayer wiring substrate according to claim 8 , wherein the desmear treatment is wet etching treatment with a polyimide etching solution, or dry etching treatment by plasma treatment.
14. The method for producing a multilayer wiring substrate according to claim 8 , wherein the conductor layer is formed by metallizing all or part of the surface of the polyimide film and the inside of the via by electroless plating after the desmear treatment is performed.