JP6565936B2 - LAMINATED BOARD AND FLEXIBLE PRINTED BOARD MANUFACTURING METHOD - Google Patents

Description

  The present invention relates to a laminate and a method for producing a flexible printed board.

  Flexible printed circuit boards do not require metal foil, for example, a flexible metal-clad laminate in which a heat-resistant resin film (polyimide film, etc.) and metal foil (copper foil, etc.) are bonded together via an adhesive material (epoxy resin, etc.) It is manufactured by removing a portion by etching to form a pattern circuit.

  Recently, from the viewpoint of increasing the electrical reliability of a flexible printed circuit board, it has been studied to use a fluorine-containing resin having excellent electrical characteristics as an adhesive material for a flexible metal-clad laminate.

As a flexible metal-clad laminate using a fluorine-containing resin as an adhesive material, for example, the following has been proposed.
(1) A flexible metal-clad laminate in which a heat-resistant resin film and a metal foil are bonded together via a fluorine-containing resin film containing a fluorine-containing polymer having an acid anhydride group (Patent Document 1).
(2) Flexible metal-clad laminate in which the surface of the heat-resistant resin film and the surface of the fluorine-containing resin film are subjected to low-temperature plasma treatment, and then the heat-resistant resin film and the metal foil are bonded together via the fluorine-containing resin film (patent Reference 2).

  By the way, when manufacturing a flexible metal-clad laminate industrially, heat-resistant resin films, fluorine-containing resin films and metal foils wound around rolls are prepared, and heat-resistant resin films and fluorine-containing films are prepared from each roll. While the resin film and the metal foil are continuously fed out, they are thermally laminated by passing them continuously between a pair of metal rolls or metal belts and heating and pressurizing them.

  However, if the temperature of the metal roll or metal belt, that is, the temperature of the thermal laminate is higher than the melting point of the fluorine-containing resin contained in the fluorine-containing resin film, the fluorine-containing resin film is tensioned in the longitudinal direction. Since the resin film is heated rapidly, the resin film shrinks in the width direction at the moment when the fluorine-containing resin film is heated, and may be cut off in some cases. Therefore, when a fluorine-containing resin is used as an adhesive material, it is difficult to industrially manufacture a flexible metal-clad laminate.

  On the other hand, when the temperature of the thermal laminate is less than the melting point of the fluorine-containing resin contained in the fluorine-containing resin film, the shrinkage of the fluorine-containing resin film is suppressed, but the interface between the heat-resistant resin film and the fluorine-containing resin film, and Adhesive strength at the interface between the fluorine-containing resin film and the metal foil becomes insufficient.

International Publication No. 2006/067970 JP 2005-324511 A

  The present invention provides a method for stably producing a laminate having a sufficiently high adhesive strength at the interface between a heat-resistant resin layer and a fluorine-containing resin layer and at the interface between the fluorine-containing resin layer and a metal foil layer; Provided is a method capable of producing a laminate and a flexible printed circuit board having sufficiently high adhesive strength at the interface between the layer and the fluorine-containing resin layer and at the interface between the fluorine-containing resin layer and the metal foil layer.

The present invention has the following aspects.
[1] A method for producing a laminate having a heat-resistant resin layer, a fluorine-containing resin layer in contact with the heat-resistant resin layer, and a metal foil layer in contact with the fluorine-containing resin layer, the following step (a And a step (b).
(A) a fluorine-containing resin film containing a fluorine-containing resin (A) having 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, and a metal foil, The process of obtaining metal foil with a fluorine-containing resin layer by carrying out heat lamination below the melting point of the said fluorine-containing resin (A).
(B) The heat-resistant resin film containing the heat-resistant resin (B) and the metal foil with the fluorine-containing resin layer are arranged such that the heat-resistant resin film and the fluorine-containing resin layer are in contact with each other. A step of obtaining the laminate by heat laminating at or above the melting point of A).
[2] The method for producing a laminated board according to [1], wherein the fluorine-containing resin (A) has a melting point of 260 to 320 ° C. and can be melt-molded.
[3] The fluorine-containing resin (A) contains the functional group derived from at least one selected from the group consisting of a monomer, a chain transfer agent and a polymerization initiator used in the production of the polymer. The manufacturing method of the laminated board of [1] or [2] which is a fluoropolymer.
[4] The thermal lamination in the step (a) and the thermal lamination in the step (b) are continuously performed by a thermal laminator having a pair of metal rolls or a pair of metal belts. 3] The manufacturing method of the laminated board in any one of.
[5] The fluororesin (A) has at least a carbonyl group-containing group as the functional group, and the carbonyl group-containing group has a carbonyl group between carbon atoms of a hydrocarbon group, a carbonate group, a carboxy group The manufacturing method of the laminated board in any one of [1]-[4] which is at least 1 sort (s) chosen from the group which consists of a group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride group.
[6] The laminate according to any one of [1] to [5], wherein the content of the functional group is 10 to 60000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluororesin (A). A manufacturing method of a board.
[7] In the step (a), the fluororesin film and the metal foil are heat-laminated at a temperature equal to or lower than (the melting point of the fluororesin (A) —20 ° C.). The manufacturing method of any laminated board.
[8] The method for producing a laminated board according to any one of [1] to [7], wherein the fluorine-containing resin layer has a thickness of 1 to 20 μm.
[9] The laminated plate according to any one of [1] to [8], wherein the fluorine-containing resin (A) has a melt flow rate of 0.5 to 15 g / 10 min under the conditions of 372 ° C. and a load of 49 N. Production method.
[10] A flexible printed circuit board in which a laminated board is produced by the production method of any one of [1] to [9], and then an unnecessary portion of the metal foil layer of the laminated board is removed by etching to form a patterned circuit Manufacturing method.

  According to the method for producing a laminate of the present invention, a laminate having a sufficiently high adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer and the interface between the fluorine-containing resin layer and the metal foil layer can be stably produced. Can be manufactured. In addition, the flexible printed board obtained by the production method of the present invention is a laminate having a sufficiently high adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer and at the interface between the fluorine-containing resin layer and the metal foil layer. Since it is formed from, it has a highly stable and reliable characteristic over a long period of time.

It is a schematic cross section which shows an example of the laminated board of this invention. It is a schematic cross section which shows the other example of the laminated board of this invention. It is a schematic block diagram which shows an example of the hot roll laminating apparatus used for a process (a). It is a schematic block diagram which shows an example of the hot roll laminating apparatus used for a process (b).

The following definitions of terms apply throughout this specification and the claims.
“Heat resistant resin” means a polymer compound having a melting point of 280 ° C. or higher, or a polymer compound having a maximum continuous use temperature defined by JIS C 4003: 2010 (IEC 60085: 2007) of 121 ° C. or higher.
“Fluorine-containing resin” means a polymer compound having a fluorine atom in the molecule.
The “melting point” means a temperature corresponding to the maximum value of the melting peak measured by the differential scanning calorimetry (DSC) method.
“Thermal lamination” means that two or more members are bonded together by heating.
“Melt moldable” means exhibiting melt fluidity.
“Showing melt fluidity” means that there is a temperature at which the melt flow rate is 0.1 to 1000 g / 10 min at a temperature higher than the melting point of the resin by 20 ° C. or more under the condition of a load of 49 N. .
The “melt flow rate” means a melt mass flow rate (MFR) defined in JIS K 7210: 1999 (ISO 1133: 1997).
The “carbonyl group-containing group” means a group having a carbonyl group (—C (═O) —) in the structure.
The “acid anhydride group” means a group represented by —C (═O) —O—C (═O) —.
“Unit” means a unit derived from a monomer formed by polymerization of the monomer. The unit may be a unit directly formed by a polymerization reaction, or may be a unit in which a part of the unit is converted into another structure by treating the polymer.
“Monomer” means a compound having a polymerizable carbon-carbon double bond.

<Laminated plate>
The “laminate of the present invention” means one obtained by the method for producing a laminate of the present invention described later. As a laminated board of this invention, what is called a flexible metal tension laminated board used as a material of a flexible printed circuit board is mentioned.
The laminate of the present invention has a heat resistant resin layer, a fluorine-containing resin layer in contact with the heat-resistant resin layer, and a metal foil layer in contact with the fluorine-containing resin layer.

  FIG. 1 is a schematic cross-sectional view showing an example of a laminated board of the present invention. The laminated plate 10 includes a heat-resistant resin layer 12, a fluorine-containing resin layer 14 laminated on the first surface of the heat-resistant resin layer 12, and the fluorine-containing resin layer 14 on the side opposite to the heat-resistant resin layer 12. And a metal foil layer 16 laminated on the surface.

  FIG. 2 is a schematic cross-sectional view showing another example of the laminated board of the present invention. The laminated plate 10 includes a heat resistant resin layer 12, two fluorine-containing resin layers 14 laminated on the first surface and the second surface of the heat resistant resin layer 12, and the heat resistance of each fluorine-containing resin layer 14. It has two metal foil layers 16 laminated on the surface opposite to the resin layer 12.

  The thickness of the laminated board of this invention is 10-2500 micrometers normally, and 12-300 micrometers is preferable from a viewpoint used for a flexible printed circuit board, 18-150 micrometers is more preferable, and 20-100 micrometers is further more preferable.

(Heat resistant resin layer)
The heat-resistant resin layer is a layer made of a heat-resistant resin film, which will be described later, and includes a heat-resistant resin (B) (excluding the fluorine-containing resin (A)). The heat resistant resin layer may contain an additive and the like to be described later as long as the effects of the present invention are not impaired.
The heat resistant resin layer may have a single layer structure or a laminated structure of two or more layers.

  The thickness of the heat resistant resin layer is preferably 3 to 500 μm, more preferably 5 to 200 μm, and still more preferably 6 to 50 μm. If the thickness of the heat resistant resin layer is equal to or greater than the lower limit, the electrical insulation is excellent. If the thickness of the heat-resistant resin layer is not more than the above upper limit value, the entire thickness of the laminate can be reduced.

  1 type may be sufficient as the heat resistant resin (B) contained in a heat resistant resin layer, and 2 or more types may be sufficient as it. The content of the heat resistant resin (B) in the heat resistant resin layer is preferably 50% by mass or more, preferably 80% by mass or more, out of 100% by mass of the heat resistant resin layer, from the viewpoint of heat resistance of the heat resistant resin layer. Is more preferable. The upper limit of this content is not specifically limited, 100 mass% may be sufficient.

  Examples of the heat resistant resin (B) include polyimide (aromatic polyimide, etc.), polyarylate, polysulfone, polyallylsulfone (polyethersulfone, etc.), aromatic polyamide, aromatic polyether amide, polyphenylene sulfide, polyallyl ether ketone. , Polyamideimide, liquid crystal polyester and the like.

  As the heat resistant resin (B), polyimide is preferable. The polyimide may be a thermosetting polyimide or a thermoplastic polyimide. As the polyimide, aromatic polyimide is preferable. The aromatic polyimide is preferably a wholly aromatic polyimide produced by condensation polymerization of an aromatic polycarboxylic dianhydride and an aromatic diamine.

Polyimide is usually obtained via polyamic acid (polyimide precursor) by reaction (polycondensation) of polycarboxylic dianhydride (or its derivative) and diamine.
Polyimides, especially aromatic polyimides, are insoluble in solvents and the like due to their rigid main chain structure and have infusible properties. Therefore, first, a polyimide precursor (polyamic acid or polyamic acid) that is soluble in an organic solvent is synthesized by a reaction between a polyvalent carboxylic dianhydride and a diamine, and molding processing can be performed by various methods at the polyamic acid stage. Done. Thereafter, the polyamic acid is subjected to a dehydration reaction by heating or a chemical method to be cyclized (imidized) to obtain a polyimide.

Specific examples of the aromatic polyvalent carboxylic dianhydride include, for example, those described in JP-A-2012-145676, [0055]. Further, ethylene tetracarboxylic dianhydride and cyclopentane tetracarboxylic dianhydride, which are non-aromatic polyvalent carboxylic dianhydrides, can be used as well as aromatic ones.
One type of polyvalent carboxylic acid dianhydride may be used alone, or two or more types may be used in combination.

  Specific examples of the aromatic diamine include those described in JP-A-2012-145676, [0057]. An aromatic diamine may be used individually by 1 type, and may use 2 or more types together.

The heat resistant resin layer may contain an additive. As such an additive, an inorganic filler having a low dielectric constant and dielectric loss tangent is preferable.
Inorganic fillers include silica, clay, talc, calcium carbonate, mica, diatomaceous earth, alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, calcium hydroxide, magnesium hydroxide, water Aluminum oxide, basic magnesium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dosonite, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass Examples thereof include beads, silica-based balloons, carbon black, carbon nanotubes, carbon nanohorns, graphite, carbon fibers, glass balloons, carbon burns, wood flour, and zinc borate. An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

The inorganic filler may be porous or non-porous, and is preferably porous from the viewpoint of lower dielectric constant and dielectric loss tangent. The inorganic filler may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanate coupling agent from the viewpoint of improving dispersibility in the resin.
0.1-100 mass parts is preferable with respect to 100 mass parts of heat resistant resin (B), and, as for content of additives, such as an inorganic filler in a heat resistant resin layer, 0.1-60 mass parts is more preferable. .

(Fluorine-containing resin layer)
The fluorine-containing resin layer is a layer made of a fluorine-containing resin film described later, and includes a specific fluorine-containing resin (A). The fluorine-containing resin layer may contain other resins, additives and the like as long as the effects of the present invention are not impaired. The fluorine-containing resin layer may have a single layer structure or a laminated structure of two or more layers.

  The thickness of the fluorine-containing resin layer is usually 1 to 1000 μm, preferably 1 to 20 μm, more preferably 3 to 20 μm, and further preferably 3 to 15 μm from the viewpoint of heat resistance against a soldering iron or the like. If the thickness of the fluorine-containing resin layer is not more than the above upper limit value, the entire thickness of the laminate can be reduced. If the thickness of the fluororesin layer is not less than the above lower limit value, the fluororesin layer will expand (foam) due to heat when the heat-resistant resin layer is exposed to an atmosphere corresponding to solder reflow at a high temperature. It is difficult and has excellent electrical insulation.

The fluorine-containing resin layer may be laminated only on the first surface of the heat resistant resin layer, or may be laminated on the first surface and the second surface of the heat resistant resin layer. From the standpoint of obtaining a double-sided metal-clad laminate with excellent electrical reliability that suppresses warpage of the laminate, a fluorine-containing resin layer is laminated on the first surface and the second surface of the heat-resistant resin layer. Is preferred.
When laminating a fluorine-containing resin layer on the first surface and the second surface of the heat-resistant resin layer, the composition of each fluorine-containing resin layer (type of fluorine-containing resin (A), types of other resins and additives, and , Their contents, etc.) and thickness may be the same or different. From the viewpoint of suppressing the warpage of the laminate, the composition and thickness of each fluororesin layer are preferably the same.

1 type may be sufficient as the fluorine-containing resin (A) contained in a fluorine-containing resin layer, and 2 or more types may be sufficient as it.
The content of the fluorine-containing resin (A) in the fluorine-containing resin layer is 100% by mass of the fluorine-containing resin layer from the viewpoint of adhesive strength at the interface between the fluorine-containing resin layer and the heat-resistant resin layer or the metal foil layer. Among these, 50 mass% or more is preferable and 80 mass% or more is more preferable. The upper limit of content of a fluorine-containing resin (A) is not specifically limited, 100 mass% may be sufficient.

  The fluorine-containing resin (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 (hereinafter referred to as functional group (I)). Resin. By having the functional group (I), the adhesive strength at the interface between the fluorine-containing resin layer containing the fluorine-containing resin (A) and the heat-resistant resin layer or the metal foil layer is increased.

From the viewpoint of adhesive strength at the interface between the fluorine-containing resin layer and the heat-resistant resin layer or the metal foil layer, the functional group (I) is composed of end groups of the main chain and pendant groups of the main chain of the fluorine-containing resin (A). It is preferably present as either one or both.
The functional group (I) may be one type or two or more types.

  The fluororesin (A) preferably has at least a carbonyl group-containing group as the functional group (I) from the viewpoint of adhesive strength at the interface between the fluororesin layer and the heat resistant resin layer or metal foil layer. Examples of the carbonyl group-containing group include a group having a carbonyl group between carbon atoms of a hydrocarbon group, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group, an acid anhydride group, and the like.

Examples of the hydrocarbon group in the group having a carbonyl group between carbon atoms of the hydrocarbon group include an alkylene group having 2 to 8 carbon atoms. In addition, carbon number of this alkylene group is carbon number in the state which does not contain a carbonyl group. The alkylene group may be linear or branched.
The haloformyl group is represented by —C (═O) —X (where X is a halogen atom). Examples of the halogen atom in the haloformyl group include a fluorine atom and a chlorine atom, and a fluorine atom is preferable. That is, the haloformyl group is preferably a fluoroformyl group (also referred to as a carbonyl fluoride group).
The alkoxy group in the alkoxycarbonyl group may be linear or branched, is preferably an alkoxy group having 1 to 8 carbon atoms, and is particularly preferably a methoxy group or an ethoxy group.

The content of the functional group (I) in the fluororesin (A) is preferably 10 to 60000, more preferably 100 to 50000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluororesin (A). 100 to 10,000 are more preferable, and 300 to 5000 are particularly preferable. If content of functional group (I) is more than the said lower limit, the adhesive strength in the interface of a fluorine-containing resin layer and a heat resistant resin layer or a metal foil layer will become still higher. If the content of the functional group (I) is not more than the above upper limit value, the adhesive strength at the interface between the fluorine-containing resin layer and the heat-resistant resin layer or metal foil layer can be increased even if the temperature of the thermal laminate is lowered. .

  The content of the functional group (I) can be measured by a method such as nuclear magnetic resonance (NMR) analysis or infrared absorption spectrum analysis. For example, using a method such as infrared absorption spectrum analysis as described in JP-A-2007-314720, the proportion of units having the functional group (I) in all units constituting the fluororesin (A) ( Mol%) and the content of the functional group (I) can be calculated from the ratio.

The melting point of the fluororesin (A) is preferably 260 to 320 ° C, more preferably 295 to 315 ° C, and further preferably 295 to 310 ° C. When the melting point of the fluororesin (A) is not less than the lower limit, the heat resistance of the fluororesin layer is excellent. If melting | fusing point of a fluororesin (A) is below the said upper limit, it is excellent in the moldability of a fluororesin (A).
The melting point of the fluororesin (A) can be adjusted by the type and ratio of units constituting the fluororesin (A), the molecular weight of the fluororesin (A), and the like. For example, the melting point tends to increase as the proportion of the unit (u1) described later increases.

As the fluorine-containing resin (A), a resin that can be melt-molded is preferable from the viewpoint of easily producing a fluorine-containing resin film described later.
As the fluorine-containing resin (A) that can be melt-molded, known fluorine-containing resins that can be melt-molded (tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer, ethylene / tetra A fluororesin in which a functional group (I) is introduced into a fluoroethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene / chlorotrifluoroethylene copolymer, etc .; a fluoropolymer (α1) described later, etc. Is mentioned.

  As the fluororesin (A), the melt flow rate is 0.1 to 1000 g / 10 min (preferably 0.5 at a temperature higher by 20 ° C. or higher than the melting point of the fluororesin (A) under a load of 49 N. Those having a temperature of ˜100 g / 10 minutes, more preferably 1-30 g / 10 minutes, still more preferably 5-20 g / 10 minutes) are preferred. When the melt flow rate is at least the lower limit, the moldability of the fluororesin (A) is excellent, and the surface smoothness and appearance of the fluororesin layer are excellent. When the melt flow rate is equal to or less than the upper limit, the mechanical strength of the fluororesin layer is excellent.

  The melt flow rate of the fluororesin (A) under the conditions of 372 ° C. and a load of 49 N is preferably 0.5 to 15 g / 10 minutes, more preferably 1 to 15 g / 10 minutes, and further preferably 1 to 12 g / 10 minutes. preferable. If the melt flow rate is less than or equal to the upper limit, the soldering iron heat resistance tends to be improved. When the melt flow rate is equal to or higher than the lower limit, the moldability of the fluororesin (A) is excellent.

  The melt flow rate is a measure of the molecular weight of the fluorine-containing resin (A). When the melt flow rate is large, the molecular weight is small, and when the melt flow rate is small, the molecular weight is large. The molecular weight of the fluorinated resin (A) and thus the melt flow rate can be adjusted by the production conditions of the fluorinated resin (A). For example, if the polymerization time is shortened during the polymerization of the monomer, the melt flow rate tends to increase. In order to reduce the melt flow rate, a method in which the fluorine-containing resin (A) is heat-treated to form a crosslinked structure and the molecular weight is increased; the amount of radical polymerization initiator used in producing the fluorine-containing resin (A) is reduced. The method of reducing; etc. are mentioned.

Examples of the fluororesin (A) include the following, depending on the production method.
(Α) A fluorine-containing polymer having a functional group (I) derived from at least one selected from the group consisting of a monomer, a chain transfer agent and a polymerization initiator used in the production of the polymer.
(Β) A fluorine-containing resin in which a functional group (I) is introduced into a fluorine-containing resin having no functional group (I) by surface treatment such as corona discharge treatment or plasma treatment.
(Γ) A fluorine-containing resin obtained by graft polymerization of a monomer having a functional group (I) to a fluorine-containing resin having no functional group (I).

The fluorine-containing resin (A) is preferably a fluorine-containing polymer (α) for the following reasons.
In the fluorinated polymer (α), the functional group (I) is present in either one or both of the end group of the main chain and the pendant group of the main chain of the fluorinated polymer (α). The adhesive strength at the interface between the layer and the heat resistant resin layer or metal foil layer is further increased.
The functional group (I) in the fluororesin (β) is unstable because it is formed by the surface treatment and easily disappears with time.

When the functional group (I) in the fluoropolymer (α) is derived from the monomer used for the production of the fluoropolymer (α), the fluoropolymer (α) is obtained by the following method (1) Can be manufactured. In this case, the functional group (I) is present in a unit derived from the monomer formed by polymerization of the monomer during production.
Method (1): A monomer having a functional group (I) is used when the fluoropolymer (α) is produced by polymerization of monomers.

When the functional group (I) in the fluoropolymer (α) is derived from the chain transfer agent used for the production of the fluoropolymer (α), the fluoropolymer (α) is obtained by the following method (2) Can be manufactured. In this case, the functional group (I) exists as a terminal group of the main chain of the fluoropolymer (α).
Method (2): A fluoropolymer (α) is produced by polymerizing monomers in the presence of a chain transfer agent having a functional group (I).
Examples of the chain transfer agent having the functional group (I) include acetic acid, acetic anhydride, methyl acetate, ethylene glycol, propylene glycol and the like.

When the functional group (I) in the fluoropolymer (α) is derived from the polymerization initiator used for the production of the fluoropolymer (α), the fluoropolymer (α) is obtained by the following method (3): Can be manufactured. In this case, the functional group (I) exists as a terminal group of the main chain of the fluoropolymer (α).
Method (3): A fluoropolymer (α) is produced by polymerizing a monomer in the presence of a polymerization initiator such as a radical polymerization initiator having a functional group (I).
Examples of the radical polymerization initiator having a functional group (I) include di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, tert-butyl peroxyisopropyl carbonate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, and di-2. -Ethylhexyl peroxydicarbonate and the like.

When the functional group (I) in the fluoropolymer (α) is derived from two or more of the monomers, chain transfer agents, and polymerization initiators used in the production of the fluoropolymer (α), The fluoropolymer (α) can be produced by using two or more of the methods (1) to (3) in combination.
As the fluorine-containing polymer (α), the content of the functional group (I) can be easily controlled. Therefore, the single polymer produced by the method (1) is easy to adjust the adhesive strength with the metal foil layer. A fluorine-containing polymer (α) having a functional group (I) derived from a monomer is preferred.

As the fluorine-containing polymer (α) having a functional group (I) derived from a monomer, the adhesive strength at the interface between the fluorine-containing resin layer and the heat-resistant resin layer or the metal foil layer is further increased, The following fluoropolymer (α1) is particularly preferred.
A unit (u1) derived from tetrafluoroethylene (hereinafter also referred to as “TFE”), a unit (u2) derived from a cyclic hydrocarbon monomer having an acid anhydride group, and a fluorine-containing monomer (provided that , A fluoropolymer (α1) having a unit (u3) derived from TFE). Here, the acid anhydride group of the unit (u2) corresponds to the functional group (I).

  Examples of the monomer constituting the unit (u2) include itaconic anhydride (hereinafter also referred to as “IAH”), citraconic anhydride (hereinafter also referred to as “CAH”), and 5-norbornene-2,3-dicarboxylic acid. Examples thereof include acid anhydrides (hereinafter also referred to as “NAH”), maleic anhydride, and the like. These monomers may be used alone or in combination of two or more.

  The monomer constituting the unit (u2) is preferably at least one selected from the group consisting of IAH, CAH and NAH. In such a case, a fluorine-containing polymer (α1) having an acid anhydride group can be easily produced without using a special polymerization method required when maleic anhydride is used (see JP-A-11-19312). it can. The monomer constituting the unit (u2) is preferably NAH because the adhesive strength at the interface between the fluorine-containing resin layer and the heat-resistant resin layer or metal foil layer is further increased.

The fluorine-containing monomer constituting the unit (u3) is preferably a fluorine-containing compound having one polymerizable carbon-carbon double bond. For example, fluoroolefin (vinyl fluoride, vinylidene fluoride (hereinafter referred to as “VdF”). ), Trifluoroethylene, chlorotrifluoroethylene (hereinafter also referred to as “CTFE”), hexafluoropropylene (hereinafter also referred to as “HFP”), etc., except TFE), CF _2. = CFOR ^f1 (where R ^f1 is a perfluoroalkyl group having 1 to 10 carbon atoms and may contain an oxygen atom between carbon atoms), CF ₂ = CFOR ^f2 SO ₂ X ¹ (where R ^f2 is the number of carbon atoms) 10 in an even better perfluoroalkylene group contain an oxygen atom between carbon atoms, X ¹ is a halogen atom or a hydroxyl group. ^{_{, CF 2 = CFOR f3 CO 2}} X 2 ( provided ^{that, R f3} is also good perfluoroalkylene group contain an oxygen atom between carbon atoms at 1 to 10 carbon atoms, ^{X 2} is a hydrogen atom or 1 to 3 carbon atoms Is an alkyl group.), CF ₂ = CF (CF ₂ ) _p OCF═CF ₂ (where p is 1 or 2), CH ₂ = CX ³ (CF ₂ ) _q X ⁴ (where X ³ Is a hydrogen atom or a fluorine atom, q is an integer of 2 to 10, and X ⁴ is a hydrogen atom or a fluorine atom.), Perfluoro (2-methylene-4-methyl-1,3-dioxolane), etc. Can be mentioned.

The fluorine-containing monomer constituting the unit (u3) includes at least one selected from the group consisting of VdF, CTFE, HFP, CF ₂ = CFOR ^f1 , and CH ₂ = CX ³ (CF ₂ ) _q X ^4. CF ₂ = CFOR ^f1 and HFP are more preferable.
As CF ₂ = CFOR ^f1 , CF ₂ = CFOCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFO (CF ₂ ) ₈ F, etc. CF ₂ = CFOCF ₂ CF ₂ CF ₃ (hereinafter also referred to as “PPVE”) is preferable.
As CH ₂ = CX ³ (CF ₂ ) _q X ⁴ , CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ ═CF (CF ₂ ) ₃ H, CH ₂ ═CF (CF ₂ ) ₄ H and the like, and CH ₂ ═CH (CF ₂ ) ₄ F or CH ₂ ═CH (CF ₂ ) ₂ F are preferable.

The proportion of the unit (u1) is preferably 50 to 99.89 mol%, more preferably 50 to 99.4 mol%, out of the total 100 mol% of the unit (u1), the unit (u2), and the unit (u3). Preferably, 50 to 98.9 mol% is more preferable.
The proportion of the unit (u2) is preferably 0.01 to 5 mol%, more preferably 0.1 to 3 mol%, out of the total 100 mol% of the unit (u1), the unit (u2) and the unit (u3). Preferably, 0.1 to 2 mol% is more preferable.
The proportion of the unit (u3) is preferably from 0.1 to 49.99 mol%, and preferably from 0.5 to 49.9 mol, out of the total 100 mol% of the unit (u1), the unit (u2) and the unit (u3). The mol% is more preferable, and 1 to 49.9 mol% is more preferable.

  When the ratio of each unit is within the above range, the fluororesin layer is excellent in heat resistance, chemical resistance, and elastic modulus at high temperature. When the ratio of the unit (u2) is within the above range, the amount of the acid anhydride group in the fluoropolymer (α1) is appropriate, and the interface between the fluororesin layer and the heat resistant resin layer or the metal foil layer. The adhesive strength at is further increased. When the proportion of the unit (u3) is within the above range, the fluoropolymer (α1) is excellent in moldability and the fluororesin layer is excellent in bending resistance. The ratio of each unit can be calculated by melt NMR analysis, fluorine content analysis, infrared absorption spectrum analysis, etc. of the fluoropolymer (α1).

When the fluoropolymer (α1) is composed of units (u1), units (u2) and units (u3), the proportion of units (u2) is 0.01 mol%. This corresponds to the content of acid anhydride groups in) being 100 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluoropolymer (α1). The proportion of the unit (u2) is 5 mol% because the content of the acid anhydride group in the fluoropolymer (α1) is 1 × 10 ⁶ main chain carbon atoms of the fluoropolymer (α1). This corresponds to 50,000 pieces.
In the fluorinated polymer (α1), a part of the acid anhydride group in the unit (u2) is hydrolyzed, and as a result, a dicarboxylic acid (itaconic acid, Units derived from citraconic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid, etc.) may be included. When a unit derived from the dicarboxylic acid is included, the ratio of the unit is included in the ratio of the unit (u2).

In addition to the units (u1) to (u3), the fluorinated polymer (α1) is a unit derived from a non-fluorinated monomer (excluding an acid anhydride group-containing cyclic hydrocarbon monomer) ( u4) may be included.
As the non-fluorine-containing monomer, a non-fluorine-containing compound having one polymerizable carbon-carbon double bond is preferable. For example, olefins having 3 or less carbon atoms (ethylene, propylene, etc.), vinyl esters (vinyl acetate, etc.) Etc. A non-fluorine-containing monomer may be used individually by 1 type, and may use 2 or more types together.
As the non-fluorinated monomer, ethylene, propylene, or vinyl acetate is preferable, and ethylene is particularly preferable.
When the fluoropolymer (α1) has the unit (u4), the proportion of the unit (u4) is 5 to 5% with respect to 100 mol% in total of the unit (u1), the unit (u2), and the unit (u3). 90 mol% is preferable, 5-80 mol% is more preferable, and 10-65 mol% is further more preferable.

  When the total of all the units of the fluoropolymer (α1) is 100 mol%, the total of the units (u1), units (u2), and units (u3) is preferably 60 mol% or more, and 65 mol% or more. Is more preferable, and 68 mol% or more is more preferable. A preferable upper limit is 100 mol%.

Preferable specific examples of the fluoropolymer (α1) include TFE / PPVE / NAH copolymer, TFE / PPVE / IAH copolymer, TFE / PPVE / CAH copolymer, TFE / HFP / IAH copolymer, TFE / HFP / CAH copolymer, TFE / VdF / IAH copolymer, TFE / VdF / CAH copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₄ F / IAH / ethylene copolymer, TFE / CH ₂ = CH (CF ₂ ) ₄ F / CAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₂ F / IAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₂ F / And CAH / ethylene copolymer.

Production method of fluorine-containing resin (A):
The fluorine-containing resin (A) can be produced by a conventional method. When the fluororesin (A) is produced by polymerization of monomers, the polymerization method is preferably a method using a radical polymerization initiator.
Polymerization methods include bulk polymerization, solution polymerization using organic solvents (fluorinated hydrocarbons, chlorinated hydrocarbons, fluorinated chlorohydrocarbons, alcohols, hydrocarbons, etc.), aqueous media and appropriate organic solvents as required. And suspension polymerization methods using an aqueous medium and an emulsion polymerization method using an emulsifier and a solution polymerization method are preferred.

The radical polymerization initiator is preferably an initiator having a half-life of 10 hours and a temperature of 0 to 100 ° C., more preferably an initiator having a temperature of 20 to 90 ° C.
Examples of radical polymerization initiators include azo compounds (such as azobisisobutyronitrile), non-fluorinated diacyl peroxides (such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, lauroyl peroxide), and peroxydicarbonates (diisopropyl peroxydicarbonate). Peroxyester (tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, tert-butyl peroxyacetate, etc.), fluorine-containing diacyl peroxide ((Z (CF ₂ ) _r COO) ₂ (where Z is A hydrogen atom, a fluorine atom or a chlorine atom, and r is an integer of 1 to 10.)), inorganic peroxides (potassium persulfate, sodium persulfate, ammonium persulfate, etc.) and the like. Et That.

  A chain transfer agent may be used during polymerization of the monomer in order to control the melt viscosity of the fluororesin (A). Chain transfer agents include alcohol (methanol, ethanol, etc.), chlorofluorohydrocarbon (1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, etc. ), Hydrocarbons (pentane, hexane, cyclohexane, etc.).

Examples of the organic solvent used in the solution polymerization method include perfluorocarbon, hydrofluorocarbon, chlorohydrofluorocarbon, and hydrofluoroether. As for carbon number, 4-12 are preferable.
Specific examples of the perfluorocarbon include perfluorocyclobutane, perfluoropentane, perfluorohexane, perfluorocyclopentane, and perfluorocyclohexane.
Specific examples of the hydrofluorocarbon include 1-hydroperfluorohexane and the like.
Specific examples of the chlorohydrofluorocarbon include 1,3-dichloro-1,1,2,2,3-pentafluoropropane.
Specific examples of the hydrofluoroether include methyl perfluorobutyl ether and 2,2,2-trifluoroethyl 2,2,1,1-tetrafluoroethyl ether.

  The polymerization temperature is preferably 0 to 100 ° C, and more preferably 20 to 90 ° C. The polymerization pressure is preferably from 0.1 to 10 MPa, more preferably from 0.5 to 3 MPa. The polymerization time is preferably 1 to 30 hours.

When the fluoropolymer (α1) is produced, the concentration of the monomer constituting the unit (u2) during polymerization is preferably 0.01 to 5 mol% with respect to the total monomer, 3 mol% is more preferable and 0.1-2 mol% is further more preferable. When the concentration of the monomer is within the above range, the polymerization rate becomes moderate. When the concentration of the monomer is too high, the polymerization rate tends to decrease.
As the monomer constituting the unit (u2) is consumed in the polymerization, the consumed amount is continuously or intermittently supplied into the polymerization tank, and the concentration of the monomer is maintained within the above range. It is preferable.

  Other resins contained in the heat resistant resin layer are not particularly limited as long as the electrical reliability characteristics are not impaired. Examples of other resins include fluorine-containing resins other than the fluorine-containing resin (A), aromatic polyesters, polyamideimides, and thermoplastic polyimides. Of these, fluorine-containing copolymers other than the fluorine-containing resin (A) are preferable from the viewpoint of electrical reliability.

Examples of the fluorine-containing resin other than the fluorine-containing resin (A) include a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer, a tetrafluoroethylene / hexafluoropropylene copolymer, and an ethylene / tetrafluoroethylene copolymer. .
The melting point of the fluorine-containing resin other than the fluorine-containing resin (A) is preferably 280 to 320 ° C. When the melting point is within the above range, swelling (foaming) due to heat hardly occurs in the fluororesin layer when exposed to an atmosphere corresponding to solder reflow.

  Examples of the additive contained in the heat resistant resin layer include the same additives as those contained in the heat resistant resin layer, and preferred forms thereof are also the same.

(Metal foil layer)
The metal foil layer is a layer made of a metal foil. Metal foil is not specifically limited, What is necessary is just to select suitably according to the use of a laminated board. For example, when a laminated plate is used for an electronic device or an electric device, examples of the material of the metal foil include copper or a copper alloy, stainless steel or an alloy thereof, nickel or a nickel alloy (including 42 alloy), aluminum or an aluminum alloy. It is done. In ordinary laminates used for electronic equipment and electrical equipment, copper foil such as rolled copper foil and electrolytic copper foil is frequently used, and copper foil is also suitable in the present invention.

A rust prevention layer (oxide film such as chromate) or a heat-resistant layer may be formed on the surface of the metal foil. Moreover, in order to make the adhesive strength with a fluorine-containing resin layer high, you may give a coupling agent process etc. to the surface of metal foil.
The thickness of metal foil is not specifically limited, What is necessary is just the thickness which can exhibit a sufficient function according to the use of a laminated board.

  In the laminate of the present invention, the fluorine-containing resin layer has at least one functional group (I) selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group. Since (A) is included, the adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer and the interface between the fluorine-containing resin layer and the metal foil layer is sufficiently high.

<Manufacturing method of laminated board>
The manufacturing method of the laminated board of this invention has the following process (a) and process (b), and also the process (x), process (y), and process (z) implemented as needed.
(A) A step of obtaining a metal foil with a fluorine-containing resin layer by thermally laminating a fluorine-containing resin film containing the fluorine-containing resin (A) and a metal foil at a temperature lower than the melting point of the fluorine-containing resin (A).
(X) The process of correcting the curvature of the metal foil with a fluorine-containing resin layer.
(B) Melting | fusing point of fluorine-containing resin (A) so that a heat-resistant resin film and a fluorine-containing resin layer may contact | connect a heat-resistant resin film containing a heat-resistant resin (B), and a metal foil with a fluorine-containing resin layer The process of obtaining a laminated board by carrying out heat lamination above.
(Y) The process of correcting the curvature of a laminated board.
(Z) The process of heat-processing a laminated board.

(Thermal laminator)
From the viewpoint of production efficiency, the thermal lamination in the step (a) and the thermal lamination in the step (b) are continuously performed by a thermal laminating apparatus having a thermal laminating unit composed of a pair of metal rolls or a pair of metal belts. Preferably, it is done.
Examples of the heat laminating apparatus having a pair of metal rolls include a heat roll laminating apparatus. A double belt press etc. are mentioned as a heat laminating apparatus which has a pair or more metal belt.

As the thermal laminating apparatus, a hot roll laminating apparatus is preferable because the apparatus configuration is simple and it is advantageous in terms of maintenance cost.
The hot roll laminating apparatus may be an apparatus having a pair of metal rolls that can be crimped while heating two members, and the specific apparatus configuration is not particularly limited.

The heating method in the heat laminating means is not particularly limited, and for example, a conventionally known method capable of heating at a predetermined temperature such as a heat circulation method, a hot air heating method, an induction heating method, or the like can be adopted.
The pressurization method in the heat laminating means is not particularly limited, and for example, a conventionally known method that can apply a predetermined pressure, such as a hydraulic method, a pneumatic method, and a gap pressure method can be adopted.

  The thermal laminating apparatus may be provided with a feeding means for sending out each member before the thermal laminating means (a pair of metal rolls or the like), and a winding means for winding the bonded members after the thermal laminating means. May be provided. Productivity can be further improved by providing the feeding means and winding means for each member. Specific configurations of the feeding means and the winding means of each member are not particularly limited, and examples thereof include a known winder that can wind each member in a roll shape.

  In order to improve the appearance of the metal foil layer, the heat laminating apparatus is provided with a feeding means for sending out a protective material disposed between the heat laminating means and the metal foil and a winding means for winding up the protective material. May be. By providing the protective material feeding means and the winding means, the protective material can be reused by winding the protective material once used and installing it again on the delivery side. Further, when winding up the protective material, end position detecting means and winding position correcting means may be provided in order to align both ends of the protective material. Thereby, the end portions of the protective material can be aligned and wound with high accuracy, and the efficiency of reuse can be increased. Specific configurations of the protective material feeding means, the winding means, the end position detecting means, and the winding position correcting means are not particularly limited, and examples thereof include various conventionally known devices.

The protective material is not particularly limited as long as it can withstand the heating temperature at the time of thermal lamination, and heat resistant plastic film (non-thermoplastic polyimide film, etc.), metal foil (copper foil, aluminum foil, SUS foil, etc.) Etc. A non-thermoplastic polyimide film is preferred from the viewpoint of excellent balance between heat resistance and reusability.
The thickness of the non-thermoplastic polyimide film is preferably 75 μm or more. If the thickness of the non-thermoplastic polyimide film is thin, there is a risk that the role of buffering and protection during thermal lamination will not be sufficiently fulfilled. The protective material may have a single layer structure or a multilayer structure of two or more layers.

(Process (a))
A metal foil with a fluorine-containing resin layer is obtained by thermally laminating a fluorine-containing resin film and a metal foil.
The fluorine-containing resin film should just contain a fluorine-containing resin (A). The fluorine-containing resin film may be a single layer film or a laminated film. The thickness of the fluororesin film is usually 1 to 1000 μm, preferably 1 to 20 μm, more preferably 3 to 20 μm, and still more preferably 3 to 15 μm.

A fluorine-containing resin film is obtained by the following method, for example.
A method of molding the fluororesin (A) itself or a resin composition containing the fluororesin (A) into a film by a known molding method (extrusion molding method, inflation molding method, etc.).
A method for introducing a functional group (I) by subjecting a fluororesin film containing a fluororesin having no functional group (I) to a known surface treatment such as corona discharge treatment or plasma treatment.

  The fluorine-containing resin film is preferably 100-250 ° C, more preferably 150-250 ° C, still more preferably 180-250 ° C, and particularly preferably heat treatment at a temperature of the heat laminating temperature to 250 ° C. . By performing the heat treatment in advance, shrinkage of the fluorine-containing resin film in the step (a) can be reduced, and as a result, warpage of the metal foil with the fluorine-containing resin layer can be reduced.

  FIG. 3 is a schematic configuration diagram showing an example of a hot roll laminating apparatus used in the step (a). In the hot roll laminating apparatus 20, a long fluorine-containing resin film 14 ′ continuously fed from the roll 22 and a long metal foil 16 ′ continuously fed from the roll 24 are a pair of metals. The rolls 26 are overlapped and heated and pressed when continuously passing between the pair of metal rolls 26 to be heat-laminated to form a metal foil 18 with a fluororesin layer. The metal foil 18 with a fluororesin layer that has passed between the pair of metal rolls 26 is continuously wound around the roll 28.

The temperature of the metal roll or metal belt, that is, the temperature of the thermal laminate is less than the melting point of the fluororesin (A), preferably (melting point−20 ° C.) or less, more preferably (melting point−50 ° C.) or less. If the temperature of the heat laminate is not more than the above upper limit value, it is difficult to shrink in the width direction at the moment when the fluorine-containing resin film is heated, and it is difficult to cut. Further, the fluorine-containing resin film hardly adheres to the metal roll or the metal belt.
The temperature of the heat laminate is preferably (melting point of fluororesin (A) −200 ° C.) or higher, more preferably (melting point−180 ° C.) or higher, and further preferably (melting point−150 ° C.) or higher. If the temperature of the thermal laminate is equal to or higher than the lower limit, the fluororesin film and the metal foil are temporarily bonded, and the fluororesin layer and the metal foil are unlikely to peel off in a subsequent process.

  The pressure between the pair of metal rolls or the pressure between the pair of metal belts, that is, the pressure of the thermal laminate is preferably 49 to 1764 N / cm, and more preferably 98 to 1470 N / cm. If the pressure of the heat laminate is within the above range, the three conditions of the temperature of the heat laminate, the speed of the heat laminate, and the pressure of the heat laminate can be made favorable, and the productivity can be further improved.

  The thermal lamination speed is preferably 0.5 m / min or more, and more preferably 1.0 m / min or more. If the thermal lamination speed is 0.5 m / min or more, sufficient thermal lamination is possible. If the heat laminating speed is 1.0 m / min or more, the productivity can be further improved.

  In the metal foil with a fluororesin layer, the adhesive strength at the interface between the fluororesin layer and the metal foil is preferably 0.1 N / cm or more, more preferably 0.2 N / cm or more, and further preferably 0.3 N / cm or more. . If the adhesive strength is equal to or higher than the lower limit, peeling between the fluororesin layer and the metal foil is unlikely to occur in the subsequent process.

(Process (x))
In the step (a), the warp of the metal foil with a fluorine-containing resin layer can be suppressed by reducing the thickness of the fluorine-containing resin film or lowering the temperature of the thermal laminate.
Nevertheless, if warpage occurs in the metal foil with a fluorinated resin layer in the step (a), the warpage of the metal foil with a fluorinated resin layer is performed by performing the step (x) before the step (b). You may correct it.

  The correction of the warpage of the metal foil with a fluorine-containing resin layer in the step (x) is preferably 100 to 250 ° C., more preferably 150 to 250 ° C., further preferably 180 to 250 ° C., to the metal foil with a fluorine-containing resin layer. Particularly preferably, the heat treatment is carried out at a temperature of the heat laminating temperature or higher and 250 ° C. or lower.

(Process (b))
A heat-resistant resin film and a metal foil with a fluorine-containing resin layer are thermally laminated so that the heat-resistant resin film and the fluorine-containing resin layer are in contact with each other to obtain a laminate. At the time of thermal lamination, the metal foil with a fluorine-containing resin layer may be disposed only on the first surface of the heat resistant resin film, or disposed on the first surface and the second surface of the heat resistant resin film. May be.

The heat resistant resin film only needs to contain the heat resistant resin (B), and may be a single layer film or a laminated film.
The thickness of the heat resistant resin film is preferably 3 to 500 μm, more preferably 5 to 200 μm, and still more preferably 6 to 50 μm.

  For example, the heat-resistant resin film is formed into a film shape by a known molding method (extrusion molding method, inflation molding method, etc.) using the heat-resistant resin (B) itself or a resin composition containing the heat-resistant resin (B). Obtained by the method.

  FIG. 4 is a schematic configuration diagram showing an example of a hot roll laminating apparatus used in the step (b). In the hot roll laminating apparatus 30, continuous from a long heat-resistant resin film 12 ′ continuously fed from a roll 32 and a roll 28 in which the metal foil 18 with a fluororesin layer is wound up in the step (a). The metal foil 18 with the long fluorine-containing resin layer fed to the pair of metal rolls 36 is superposed on the pair of metal rolls 36 and is heated and pressurized when continuously passing between the pair of metal rolls 36. Thus, the laminate 10 is obtained. The laminated plate 10 that has passed between the pair of metal rolls 36 is continuously wound around the roll 38.

The temperature of the metal roll or metal belt, that is, the temperature of the thermal lamination is not less than the melting point of the fluororesin (A), preferably (melting point + 10 ° C.) or more, and more preferably (melting point + 20 ° C.) or more. If the temperature of the heat laminating is not more than the above upper limit value, the heat resistant resin film and the metal foil with a fluorine-containing resin layer can be heat laminated well. If the temperature of the thermal laminate is (melting point + 20 ° C.) or higher, the speed of the thermal laminate can be increased to further improve the productivity.
The temperature of the thermal laminate is preferably 420 ° C. or lower, and more preferably 400 ° C. or lower.

  The pressure between the pair of metal rolls or the pressure between the pair of metal belts, that is, the pressure of the thermal laminate is preferably 49 to 1764 N / cm, and more preferably 98 to 1600 N / cm. If the pressure of the heat laminate is within the above range, the three conditions of the temperature of the heat laminate, the speed of the heat laminate, and the pressure of the heat laminate can be made favorable, and the productivity can be further improved.

  The thermal lamination speed is preferably 0.5 m / min or more, and more preferably 1.0 m / min or more. If the thermal lamination speed is 0.5 m / min or more, sufficient thermal lamination is possible. If the heat laminating speed is 1.0 m / min or more, the productivity can be further improved.

The adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer in the laminate is preferably 5 N / cm or more, more preferably 6 N / cm or more, and even more preferably 7 N / cm or more.
The adhesive strength at the interface between the fluororesin layer and the metal foil in the laminate is preferably 7 N / cm or more, more preferably 8 N / cm or more, and further preferably 10 N / cm or more.

(Process (y))
When warpage occurs in the laminate in the step (b), the warpage of the laminate may be corrected by performing the step (y).
The correction of the warpage of the laminate in the step (y) is preferably performed at 100 to 250 ° C., more preferably 150 to 250 ° C., further preferably 180 to 250 ° C., particularly preferably 250 ° C. above the temperature of the thermal laminate. In the following, the heat treatment is performed.

(Process (z))
In order to improve the soldering iron heat resistance of the laminated board and the adhesive strength between each layer of the laminated board, the step (z) is carried out and the laminated board is subjected to heat treatment to melt the fluorine-containing resin (A). The flow rate may be reduced. The heat treatment in the step (z) is performed using, for example, the above-described thermal laminating apparatus. The temperature of the heat treatment is preferably 370 ° C. or higher, and more preferably 380 ° C. or higher. The upper limit in this case is usually 420 ° C. or lower, preferably 400 ° C. or lower.

  In addition, a flexible printed circuit board, which will be described later, can be obtained by subjecting the laminate to heat treatment at a temperature equal to or higher than the melting point of the fluororesin (A) in an environment with a low oxygen concentration in an inert gas atmosphere such as nitrogen or argon, or in a vacuum. Dimensional stability when passing through the solder reflow process and other heat treatment processes (coverlay mounting, etc.) is improved. The heat treatment conditions are preferably (melting point of fluororesin (A) + 10 ° C. to 120 ° C.) for 5 seconds to 48 hours, more preferably (melting point of fluororesin (A) + 30 ° C. to 100 ° C.) For 30 seconds to 36 hours, more preferably (melting point of fluororesin (A) + 40 ° C. to 80 ° C.) for 1 minute to 24 hours.

  Further, the heat treatment improves the adhesion between the metal foil and the fluorine-containing resin layer, and between the fluorine-containing resin layer and the heat-resistant resin film. When such heat treatment is performed, a laminate having a sufficiently high adhesive strength at the interface can be obtained even if the pressure of the thermal laminate in steps (a) and (b) is lowered. Note that when the thermal laminating pressure is increased, the dimensional stability of the laminate and further the flexible printed circuit board described later tends to deteriorate. However, when such heat treatment is performed, the thermal laminating pressure can be lowered, so that the dimensional stability is improved. improves.

In the method for producing a laminate of the present invention, the fluororesin film and the metal foil are thermally laminated at a temperature lower than the melting point of the fluororesin (A) in the step (a). It is hard to cut. And in the step (b), since the heat-resistant resin film and the metal foil with the fluorine-containing resin layer are thermally laminated at a melting point or higher of the fluorine-containing resin (A), the interface between the heat-resistant resin film and the fluorine-containing resin film , And the adhesive strength at the interface between the fluororesin film and the metal foil is sufficiently high. In the thermal lamination in the step (b), the fluororesin film is temporarily bonded to the metal foil and supported by the metal foil. Therefore, the thermal lamination is performed at a temperature equal to or higher than the melting point of the fluororesin (A). However, the fluorine-containing resin film is difficult to heat shrink in the width direction and is not easily cut.
From the above, it is possible to stably produce a laminate having a sufficiently high adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer and at the interface between the fluorine-containing resin layer and the metal foil layer.

<Flexible printed circuit board>
The flexible printed circuit board of the present invention includes a pattern circuit formed by removing unnecessary portions of the metal foil layer of the laminated board of the present invention by etching.
The flexible printed circuit board of the present invention may be mounted with various miniaturized and densified components.

  In the flexible printed board of the present invention, the fluorine-containing resin layer has at least one functional group (I) selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group. Since the resin (A) is contained, the adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer and the interface between the fluorine-containing resin layer and the metal foil layer is sufficiently high.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. Examples 1, 2 and 3 are examples, and examples 4 and 5 are comparative examples.

(Copolymerization composition)
The copolymer composition of the fluororesin (A) was determined by melt NMR analysis, fluorine content analysis, and infrared absorption spectrum analysis.

(Content of functional group (I))
The proportion of units derived from NAH having the functional group (I) in the fluororesin (A) was determined by the following infrared absorption spectrum analysis.
The fluorine-containing resin (A) was press-molded to obtain a 200 μm film. In the infrared absorption spectrum, an absorption peak in a unit derived from NAH in the fluororesin (A) appears at 1778 cm ⁻¹ . The absorbance of the absorption peak was measured, and the ratio (mol%) of units derived from NAH was determined using the NAH molar extinction coefficient of 20810 mol ⁻¹ · l · cm ⁻¹ .
When the ratio to a (mol%), the number of functional groups (I) (acid anhydride group) relative to the main chain number 1 × 10 ⁶ carbon atoms is calculated as [a × ¹⁰ 6/100] Pieces.

(Melting point)
Using a differential scanning calorimeter (DSC apparatus, manufactured by Seiko Instruments Inc.), the melting peak when the fluororesin (A) was heated at a rate of 10 ° C./min was recorded, and the temperature corresponding to the maximum value (° C. ) As the melting point.

(Melting flow rate)
Using a melt indexer (manufactured by Techno Seven Co., Ltd.), a fluorine-containing resin that flows out for 10 minutes from a nozzle having a diameter of 2 mm and a length of 8 mm under conditions of 372 ° C. and a load of 49 N, which is 20 ° C. higher than the melting point ) (G) was measured.

(Adhesive strength)
Interface between fluorine-containing resin layer and metal foil layer:
An evaluation sample was prepared by cutting a metal foil or laminate with a fluororesin layer into a size of 150 mm in length and 10 mm in width. The fluororesin layer and the metal foil were peeled from one end in the length direction of the evaluation sample to a position of 50 mm. Subsequently, it peeled so that it might become 90 degree | times at the tension | pulling speed of 50 mm / min using the tensile tester, and let the maximum load be adhesive strength (N / cm).

Interface between heat resistant resin layer and fluorine-containing resin layer:
The laminate was cut into a size of 150 mm in length and 10 mm in width to produce an evaluation sample. The heat-resistant resin layer and the fluorine-containing resin layer were peeled from one end in the length direction of the evaluation sample to a position of 50 mm. Subsequently, it peeled so that it might become 90 degree | times at the tension | pulling speed of 50 mm / min using the tensile tester, and let the maximum load be adhesive strength (N / cm).

(Fluorine-containing resin (A-1))
NAH (anhydrous mixed acid, manufactured by Hitachi Chemical Co., Ltd.) is used as a monomer for forming the unit (u2), and PPVE (CF ₂ = CFO (CF ₂ ) ₃ F, perfluoro is used as the monomer for forming the unit (u3). Propyl vinyl ether was prepared.
Initiation of polymerization in which (perfluorobutyryl) peroxide was dissolved in 1,3-dichloro-1,1,2,2,3-pentafluoropropane (hereinafter also referred to as AK225cb, manufactured by Asahi Glass Co.) at a concentration of 0.36% by mass An agent solution was prepared.
An NAH solution in which NAH was dissolved in AK225cb at a concentration of 0.3% by mass was prepared.

369 kg of AK225cb and 30 kg of PPVE were charged into a polymerization tank equipped with a stirrer having an internal volume of 430 L that had been degassed in advance. After the inside of the polymerization tank was ripened and heated to 50 ° C., and further charged with 50 kg of TFE, the pressure in the polymerization tank was increased to 0.89 MPa [gage].
Polymerization was carried out while continuously adding 3 liters (L) of the polymerization initiator solution to the polymerization tank at a rate of 6.25 mL / min. Further, TFE was continuously charged so that the pressure in the polymerization tank during the polymerization reaction was maintained at 0.89 MPa [gage]. The NAH solution was continuously charged in an amount corresponding to 0.1 mol% with respect to the number of moles of TFE charged during the polymerization.
After exceeding 8 hours from the start of polymerization, when 32 kg of TFE was charged, the temperature in the polymerization tank was lowered to room temperature and the pressure was purged to normal pressure. The obtained slurry was solid-liquid separated from AK225cb, and then dried at 150 ° C. for 15 hours to obtain 33 kg of a fluororesin (A-1).

The specific gravity of the fluororesin (A-1) is 2.15, and the copolymer composition is units derived from TFE / units derived from NAH / units derived from PPVE = 97.9 / 0.1 / 2. 0.0 (mol%).
Moreover, melting | fusing point of the fluororesin (A-1) was 305 degreeC, and the melt flow rate was 11.0 g / 10min.
The content of the functional group (I) (an acid anhydride group) in the fluororesin (A-1) is 1000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluororesin (A-1). there were.

(Other fluorine-containing resins)
PFA: TFE / perfluoro (alkyl vinyl ether) copolymer (Asahi Glass Co., Ltd., Fluon (registered trademark) PFA 73PT, melting point: 305 ° C., melt flow rate 13.6 g / 10 min).

(Fluorine-containing resin film 1)
The fluororesin (A-1) was extrusion molded at a die temperature of 340 ° C. using a 30 mmφ single screw extruder having a 750 mm wide coat hanger die, to obtain a fluororesin film 1 having a thickness of 25 μm.

(Fluorine-containing resin film 2)
A fluorine-containing resin film 2 having a thickness of 12.5 μm was obtained in the same manner as the fluorine-containing resin film 1 except that the take-up speed was changed.

(Fluorine-containing resin film 3)
PFA was extruded at a die temperature of 340 ° C. using a 30 mmφ single screw extruder having a 750 mm wide coat hanger die to obtain a fluororesin film 3 having a thickness of 25 μm.

(Heat resistant resin film)
A polyimide film having a thickness of 25 μm (manufactured by Toray DuPont, Kapton (registered trademark) 100EN) was prepared.

(Metal foil)
An electrolytic copper foil having a thickness of 12 μm (manufactured by Fukuda Metal Foil Powder Co., Ltd., CF-T4X-SVR-12, Rz: 1.2 μm) was prepared.

(Example 1)
Step (a):
With a fluorine-containing resin layer, the fluorine-containing resin film 1 and metal foil are heat-laminated using a heat roll laminating apparatus having a pair of metal rolls at a temperature of 230 ° C., a pressure of 784 N / cm, and a speed of 4 m / min. Metal foil 1 was produced. The adhesive strength at the interface between the fluorine-containing resin layer and the metal foil layer was 0.3 N / cm.

Step (b):
A polyimide film and a metal foil 1 with a fluorine-containing resin layer are heat laminated using a hot roll laminating apparatus having a pair of metal rolls at a temperature of 400 ° C., a pressure of 1470 N / cm, and a speed of 1 m / min. 1 was produced. The adhesive strength at the interface between the fluorine-containing resin layer and the metal foil layer was 11 N / cm, and the adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer was 8 N / cm.

(Example 2)
Step (a):
A metal foil 2 with a fluorine-containing resin layer was produced in the same manner as in Example 1 except that the fluorine-containing resin film 2 was used instead of the fluorine-containing resin film 1. The adhesive strength at the interface between the fluorine-containing resin layer and the metal foil layer was 0.3 N / cm.

Step (b):
A laminated plate 2 was produced in the same manner as in Example 1 except that the metal foil 2 with a fluorine-containing resin layer was used instead of the metal foil 1 with a fluorine-containing resin layer. The adhesive strength at the interface between the fluorine-containing resin layer and the metal foil layer was 10 N / cm, and the adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer was 7 N / cm.

(Example 3)
Step (z):
The laminated board 2 obtained in Example 2 was subjected to heat treatment to produce a laminated board 3. The heat treatment was performed using a thermal laminator under conditions of a temperature of 380 ° C., a pressure of 1470 N / cm, and a speed of 1 m / min. The adhesive strength at the interface between the fluorine-containing resin layer and the metal foil layer of the laminate 3 was 12 N / cm, and the adhesive strength at the interface between the heat-resistant resin layer and the fluorine-containing resin layer was 10 N / cm.

(Example 4)
An attempt was made to produce a metal foil with a fluorine-containing resin layer in the same manner as in Example 1 except that the fluorine-containing resin film 3 was used instead of the fluorine-containing resin film 1, but the interface between the fluorine-containing resin layer and the metal foil layer was attempted. When the metal foil with a fluorine-containing resin layer was wound up, separation occurred between the fluorine-containing resin film 3 and the metal foil.

(Example 5)
An attempt was made to heat laminate the fluororesin film 1, metal foil and polyimide film using a heat roll laminator having a pair of metal rolls at a temperature of 400 ° C., a pressure of 784 N / cm, and a speed of 4 m / min. Since the heat shrinkage of the fluororesin film 1 was large in the vicinity of the roll and the fluororesin film 1 was broken, the laminated plate could not be produced continuously.

The laminate obtained by the laminate production method of the present invention is useful for producing a flexible printed circuit board that requires a high degree of electrical reliability.
The specification, claims, drawings, and abstract of Japanese Patent Application No. 2014-264875 filed on December 26, 2014 and Japanese Patent Application No. 2015-121143 filed on June 16, 2015. The entire contents of this document are hereby incorporated by reference as the disclosure of the specification of the present invention.

  DESCRIPTION OF SYMBOLS 10 Laminated board, 12 Heat resistant resin layer, 12 'Heat resistant resin film, 14 Fluorine-containing resin layer, 14' Fluorine-containing resin film, 16 Metal foil layer 16 'Metal foil, 18 Metal foil with fluorine-containing resin layer, 20 Heat Roll laminator, 22 rolls, 24 rolls, 26 metal rolls, 28 rolls, 30 heat roll laminator, 32 rolls, 36 metal rolls, 38 rolls

Claims (10)

A method for producing a laminate having a heat-resistant resin layer, a fluorine-containing resin layer in contact with the heat-resistant resin layer, and a metal foil layer in contact with the fluorine-containing resin layer, the following steps (a) and steps The manufacturing method of a laminated board which has (b).
(A) a fluorine-containing resin film containing a fluorine-containing resin (A) having 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, and a metal foil, The process of obtaining metal foil with a fluorine-containing resin layer by carrying out heat lamination below the melting point of the said fluorine-containing resin (A).
(B) The heat-resistant resin film containing the heat-resistant resin (B) and the metal foil with the fluorine-containing resin layer are arranged such that the heat-resistant resin film and the fluorine-containing resin layer are in contact with each other. A step of obtaining the laminate by heat laminating at or above the melting point of A).   The manufacturing method of the laminated board of Claim 1 whose melting | fusing point is 260-320 degreeC and the said fluororesin (A) is melt-moldable.   The fluoropolymer (A) having the functional group derived from at least one selected from the group consisting of a monomer, a chain transfer agent and a polymerization initiator used in the production of the polymer The manufacturing method of the laminated board of Claim 1 or 2 which is.   The thermal lamination in the said process (a) and the thermal lamination in the said process (b) are performed continuously by the thermal laminating apparatus which has a pair or more metal roll or a pair or more metal belt. The manufacturing method of the laminated board of one term. The fluororesin (A) has at least a carbonyl group-containing group as the functional group,
The carbonyl group-containing group is at least one selected from the group consisting of a group having a carbonyl group between carbon atoms of a hydrocarbon group, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride group. The manufacturing method of the laminated board as described in any one of Claims 1-4. The laminate according to any one of claims 1 to 5, wherein the content of the functional group is 10 to 60000 with respect to 1 x 10 ⁶ main chain carbon atoms of the fluororesin (A). Manufacturing method.   The said process (a) WHEREIN: The said fluorine-containing resin film and the said metal foil are heat laminated at the temperature below (melting | fusing point-20 degreeC of the said fluorine-containing resin (A)). The manufacturing method of the laminated board as described in a term.   The manufacturing method of the laminated board as described in any one of Claims 1-7 whose thickness of the said fluorine-containing resin layer is 1-20 micrometers.   The production of the laminated board according to any one of claims 1 to 8, wherein the melt flow rate of the fluororesin (A) under conditions of 372 ° C and a load of 49N is 0.5 to 15 g / 10 minutes. Method.   After manufacturing a laminated board with the manufacturing method as described in any one of Claims 1-9, manufacture of the flexible printed circuit board which removes the unnecessary part of the metal foil layer of the said laminated board by an etching, and forms a pattern circuit Method.

Images