JP2017148986A - Laminate for wiring board, wiring board, and method for manufacturing laminate for wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for wiring board which causes little transmission loss; a wiring broad; and a method for manufacturing a laminate for wiring board.SOLUTION: A laminate 1 for wiring board is formed of a resin containing at least one of a polyamic acid, polyimide, polyamide imide, polyamide, polyvinylidene fluoride, a polybenzoxazole resin, a polybenzimidazole resin, polysulfone, polyaryl sulfone and polyether sulfone, and includes a porous film 2 having a plurality of gaps having spherical or continuous spherical shapes and a conductive film 4 laminated on at least one surface of the porous film 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board laminate, a wiring board, and a method for manufacturing a wiring board laminate.

  In recent years, electrical signals flowing through a wiring board tend to be increased in frequency due to high-speed and large-capacity digital signals accompanying the high performance of electronic devices and the spread of communication devices using high frequencies. It is known that transmission loss increases when a signal having a high frequency flows through the wiring board. For this reason, the wiring board is required to have a small transmission loss that can cope with a signal having a high frequency. In recent years, flexible wiring boards that enable electronic circuits to be flexible and small and light are widely used in electronic devices as wiring boards. As this flexible wiring board, for example, an imide resin is used as a base material (insulating layer) and a metal foil is laminated on at least one surface thereof.

  As a flexible wiring board for reducing transmission loss, for example, a wiring board using a porous film of an imide resin is known. Since a porous film generally has a low dielectric constant, transmission loss can be reduced. As a laminated body for a wiring board using a porous film of an imide resin, for example, a laminated body for a wiring board using a porous polyimide film formed by a phase separation method has been proposed (for example, the patent documents shown below) 1 and Patent Document 2).

JP 2005-166828 A JP 2012-101438 A

  However, as in Patent Document 1 and Patent Document 2, it is difficult to sufficiently reduce the transmission loss in the wiring board laminate in which the porous film of the imide resin is formed by the phase separation method.

  In view of the circumstances as described above, it is an object of the present invention to provide a wiring board laminate, a wiring board, and a method for manufacturing a wiring board laminate with less transmission loss.

  According to the first aspect of the present invention, at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone is included. Provided is a laminate for a wiring board comprising a porous film formed of a resin and having a plurality of spherical or spherical-shaped voids, and a conductive film laminated on at least one surface of the porous film. Is done.

  According to the second aspect of the present invention, there is provided a wiring board in which a wiring pattern is formed on at least a part of the conductive film of the laminate for wiring board of the first aspect.

  According to the third aspect of the present invention, at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone is included. There is provided a method for producing a laminate for a wiring board, comprising: forming a porous film having a plurality of voids with a resin; and laminating a conductive film on at least one surface of the porous film.

  According to the aspects of the present invention, there are provided a wiring board laminate, a wiring board, and a method for manufacturing a wiring board laminate with little transmission loss.

It is a figure which shows the example of the laminated body which concerns on 1st Embodiment. It is a flowchart which shows an example of the manufacturing method of the laminated body which concerns on 1st Embodiment. FIG. 3 is a flowchart illustrating an example of a method for manufacturing a laminate, following FIG. 2. It is a figure which shows an example of the manufacturing method of a laminated body. FIG. 5 is a diagram illustrating an example of a method for manufacturing a laminated body following FIG. 4. FIG. 6 is a diagram illustrating an example of a method for manufacturing a laminated body following FIG. 5. The other example of the manufacturing method of a laminated body is shown, (A) is a flowchart, (B) is a figure. The other example of the manufacturing method of a laminated body is shown, (A) is a flowchart, (B) is a figure. It is a figure which shows the example of the laminated body which concerns on 2nd Embodiment. It is a flowchart which shows an example of the manufacturing method of a porous membrane. It is a figure which shows an example of the manufacturing method of a porous membrane. It is a figure which shows the example of the laminated body which concerns on 3rd Embodiment. It is a figure which shows an example of the manufacturing method of a laminated body. It is a figure which shows an example of the wiring board which concerns on 4th Embodiment.

[First Embodiment]
A first embodiment will be described. FIG. 1A is a cross-sectional view showing an example of a laminated body according to the first embodiment, and FIG. 1B is a cross-sectional view showing another example of the laminated body. In the following description, the XYZ orthogonal coordinate system shown in FIG. In this XYZ orthogonal coordinate system, the X direction and the Y direction are horizontal directions (lateral directions), and the Z direction is a vertical direction. In each direction, the same side as the tip of the arrow is appropriately referred to as a + side (eg, + Z side), and the opposite side of the arrow is referred to as a − side (eg, −Z side). For example, in the vertical direction (Z direction), the upper side is the + Z side and the lower side is the -Z side. Further, in the drawings, in order to make each configuration easy to understand, a part of the structure is emphasized or a part of the structure is simplified, and an actual structure, shape, scale, or the like may be different.

  As shown in FIG. 1, the laminate 1 includes a porous film 2, a non-porous film 3, and a conductive film 4. The laminate 1 can be suitably used as a laminate for a wiring board.

  The porous membrane 2 is formed of a resin containing at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone. The Among these, the porous membrane 2 is preferably formed of an imide resin containing at least one of polyamic acid, polyimide, polyamideimide, and polyamide. When the porous film 2 is formed of such an imide resin, the laminate 1 having excellent strength, heat resistance, chemical resistance, and wear resistance can be obtained.

  The porous membrane 2 has a plurality of voids 5. In the laminate 1, for example, the transmission loss is reduced by the plurality of gaps 5. The shape of the space 5 is a spherical shape or a shape in which spherical shapes are continuous. When the shape of the void 5 is a sphere or a shape in which the spheres are continuous, the porosity can be increased while maintaining the strength of the porous membrane 2. The air gap 5 is formed by connecting at least a part of the air holes 6 to form a three-dimensional air hole. The hole 6 is a minute hole having a spherical curved surface, and a communication hole is formed at a portion where the holes 6 are connected to each other. Further, for example, the void 5 forms a through-hole that communicates the upper surface (+ Z side surface) and the lower surface (−Z side surface) of the porous membrane 2.

  The inner diameter of the void 5 (the inner diameter of the air holes 6) is not particularly limited, but is, for example, 10 nm or more and 50 μm or less, preferably 50 nm or more and 10 μm or less. For example, the inner diameter of the void 5 is uniform throughout the porous membrane 2. The inner diameter of the void 5 can be appropriately adjusted according to the particle size of the fine particles used when the porous film 2 described later is manufactured. The inner diameter of the void 5 may be uniform or non-uniform throughout the porous membrane 2.

  The porosity of the porous membrane 2 is, for example, not less than 45% and not more than 90%. When the porosity of the porous membrane 2 is in the above range, the laminate 1 having a lower transmission loss can be obtained. The porosity of the porous film 2 is set uniformly in the thickness direction (Z direction) and the surface direction (X direction, Y direction) of the porous film 2, for example. The porosity of the porous membrane 2 may be uniform or non-uniform.

The porosity indicates, for example, the ratio of voids per unit volume. The porosity is calculated by, for example, the following formula (1).
Porosity (%) = {[weight of porous membrane 2 (g) / volume of porous membrane 2 (cm ³ )] / specific gravity of resin (g / cm ³ )} × 100 (1)

  The porosity of the porous membrane 2 can be controlled by the materials used for the production of the porous membrane 2 (eg, types and contents of resin materials, plasticizers, inorganic or organic fillers), production methods, and the like. For example, a desired porosity can be obtained by appropriately adjusting the particle size and content of fine particles used in manufacturing the porous film 2 described later.

  The film thickness of the porous membrane 2 is not particularly limited, but can be 10 μm or more and 500 μm or less, preferably 15 μm or more and 250 μm or less, more preferably 20 μm or more and 200 μm or less. When the film thickness of the porous film 2 is in the above range, the laminate 1 is excellent in strength, can suppress film elongation, wrinkles, pinholes, film breakage during processing, and has low transmission loss. Can be obtained.

  The relative dielectric constant of the porous film 2 at a frequency of 1 GHz is, for example, 2.0 or less, preferably 1.8 or less, more preferably 1.6 or less. The relative dielectric constant of the porous film 2 at a frequency of 10 GHz is, for example, 2.0 or less, preferably 1.8 or less, more preferably 1.6 or less. When the relative dielectric constant of the porous film 2 is in the above range, transmission loss can be further reduced.

  In the present specification, the relative dielectric constant of the porous film 2 (porous film 2a) is set to a temperature of 27 degrees by a cavity resonator vibration method using a cavity resonator method apparatus (manufactured by AET Co., Ltd.). The value measured at a predetermined frequency under the condition of 50% humidity.

  The non-porous film 3 is a non-porous film. The nonporous film 3 is, for example, a nonporous resin film. The non-porous film 3 is disposed between the porous film 2 and the conductive film 4. The non-porous film 3 may be an adhesive that bonds the porous film 2 and the conductive film 4, for example. For example, the conductive film 4 and the non-porous film 3 are formed on a flat surface. In this case, the adhesion between the non-porous film 3 and the conductive film 4 is further improved. The non-porous membrane 3 is laminated on at least one surface of the porous membrane 2, for example. In the following description, a film in which the non-porous film 3 is laminated on at least one surface of the porous film 2 (porous film 2a (see FIG. 11)) may be referred to as “composite film 7”.

  The non-porous membrane 3 shown in FIG. 1 (A) is laminated on the entire one surface of the porous membrane 2, but the non-porous membrane 3 is at least on at least one surface of the porous membrane 2. What is necessary is just to be laminated | stacked on one part.

  The material for forming the non-porous film 3 is not particularly limited, and is formed of, for example, a known resin material. Among these, the non-porous film 3 is a resin containing at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone. Preferably, it is formed of an imide resin containing at least one of polyamic acid, polyimide, polyamideimide, and polyamide. When the non-porous film 3 is formed of an imide resin, the laminate 1 excellent in strength, heat resistance, chemical resistance, and wear resistance can be obtained.

  Note that the non-porous film 3 may not be a non-porous resin film, and may be formed as the conductive film 4 like a laminated body 1D described later with reference to FIG.

  The non-porous film 3 and the porous film 2 are formed of the same material, for example. When the non-porous film 3 and the porous film 2 are formed of the same material, the adhesion between the porous film 2 and the non-porous film 3 is further improved. In this case, the heat resistance can be further improved, and the type of the material of the laminate 1 can be reduced, so that the manufacture of the laminate 1 can be simplified. Note that the non-porous film 3 and the porous film 2 may be formed of different materials.

  The film thickness of the non-porous film 3 is not particularly limited, and is, for example, 20 μm or less, preferably 2 μm or more and 10 μm or less, more preferably 3 μm or more to 7 μm or less. When the film thickness of the non-porous film 3 is in the above range, transmission loss can be reduced and the film can be formed easily.

  Note that the non-porous film 3 may be laminated on both surfaces (the + Z side surface and the −Z side surface) of the porous film 2 as in the laminated body 1A shown in FIG. In this case, the non-porous film 3 stacked on the + Z side of the porous film 2 and the non-porous film 3 stacked on the −Z side may be formed of the same material or different materials. May be. When the non-porous film 3 laminated on the + Z side of the porous film 2 and the non-porous film 3 laminated on the −Z side are formed of the same material, the heat resistance can be improved, and And since the kind of material of the laminated body 1 can be decreased, manufacture of the laminated body 1 can be simplified. Further, the non-porous film 3 shown in FIG. 1A and the like is one layer, but the non-porous film 3 may be two or more layers.

  The conductive film 4 is laminated on at least one surface of the porous film 2. For example, the conductive film 4 is stacked on the upper surface (the surface on the + Z side) of the porous film 2. The conductive film 4 is laminated, for example, on the upper surface (the surface on the + Z side) of the porous film 2 via the non-porous film 3. The conductive film 4 is not particularly limited, and any conductive material can be used. For the conductive film 4, for example, a metal foil such as a copper foil, a stainless steel stay, an aluminum stay, or a nickel stay is used. Further, the surface of the conductive film 4 may be subjected to roughening treatment or rust prevention treatment. The thickness of the conductive film 4 is not particularly limited, and can be, for example, about 0.1 μm to 100 μm. In addition, the electrically conductive film 4 may be laminated | stacked on both surfaces of the porous film 2 like the laminated body 1A shown to FIG. 1 (B).

  Next, with reference to FIGS. 2-7, the manufacturing method of the laminated film which concerns on embodiment is demonstrated. FIG. 2, FIG. 3 and FIG. 7A are flowcharts showing an example of a method for manufacturing a laminated film according to the embodiment. 4 to 6 and 7B are cross-sectional views illustrating an example of a method for manufacturing a laminated film. The following description is an example of a manufacturing method and does not limit the manufacturing method. 2 to 7 show an example of a method for producing a porous film 2 subjected to an etching process described later.

  For example, as shown in FIG. 2, the manufacturing method of the laminate 1 of the present embodiment includes polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone in step S <b> 1. A porous membrane is formed from a resin containing at least one of polyarylsulfone and polyethersulfone.

  For example, in step S11 shown in FIG. 3, a resin film containing fine particles is applied to a substrate and dried to form a dry film. For example, first, a liquid (coating liquid L) containing a predetermined resin material, fine particles and a solvent is prepared. Specific resin materials include polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzoxazole resin precursor polymer, polybenzimidazole resin, polybenzimidazole resin precursor polymer, polysulfone , Polyarylsulfone, and polyethersulfone. Among these, at least one of polyamic acid, polyimide, polyamideimide, and polyamide is preferable. As the solvent, any organic solvent capable of dissolving the resin material to be used is used.

  The coating liquid L described above is prepared, for example, by mixing a solvent in which fine particles are dispersed in advance and at least one of polyamic acid, polyimide, polyamideimide, and polyamide at an arbitrary ratio. Alternatively, it may be prepared by polymerizing at least one of polyamic acid, polyimide, polyamideimide, and polyamide in a solvent in which fine particles are dispersed in advance. For example, it can be produced by polymerizing tetracarboxylic dianhydride and diamine in an organic solvent in which fine particles are dispersed in advance to form a polyamic acid, or by further imidizing it into a polyimide.

  The viscosity of the coating liquid L is preferably finally 300 to 5000 cP, more preferably 400 to 3000 cP, and still more preferably 600 to 2500 cP. If the viscosity of the coating liquid L is within this range, it is possible to form a film uniformly. Among all the components in the coating liquid L, the content of the solvent is, for example, 50 to 95% by mass, and preferably 60 to 85% by mass.

  For example, the coating liquid L is contained so that the resin material and the fine particles have a volume ratio of 10:90 to 50:50. As the volume of each resin material, a value obtained by multiplying the mass of each resin material by its specific gravity is used. In this case, if the volume of the fine particles is 50 or more when the entire volume of the coating liquid L is 100, the particles are uniformly dispersed, and if the volume of the fine particles is within 90, the particles are aggregated. Disperse without any problem. For this reason, the voids 5 can be uniformly formed in the porous film 2. In addition, when the volume ratio of the fine particles is within this range, it is possible to ensure releasability when forming a dry film (eg, dry film D).

  In the coating liquid L, when the fine particles and the polyamic acid or polyimide are dried to form a dry film, when the fine particles are inorganic materials described later, for example, the fine particle / polyimide ratio is 2 to 6 (mass). Ratio), preferably 3 to 5 (mass ratio), fine particles and polyamic acid or polyimide are mixed. When the material of the fine particles is an organic material described later, for example, the fine particles and the polyamic acid or polyimide so that the fine particle / polyimide ratio is 1 to 3.5 (mass ratio), preferably 1.2 to 3 (mass ratio). And mix. For example, when the fine particles are 72% by volume (up to 2.6 volume times) with respect to the resin material, silica (fine particles) / polyimide = 80/20 by mass ratio, or polymethyl methacrylate resin (fine particles) / polyimide = (68/32) to 2.1 times may be set. When the mass ratio is in the above range, the porosity can be set to an appropriate value for the porous film, and the film can be stably formed without causing problems such as an increase in viscosity and cracks in the film.

  In the case of a dry film, for example, fine particles and polyamic acid or polyimide are mixed so that the volume ratio of fine particles / polyimide is 1.5 to 4.5, preferably 1.8 to 3 (volume ratio). To do. When the volume ratio is in the above range, the porosity can be set to an appropriate value for the laminate for a wiring board, and the film can be stably formed without causing problems such as an increase in viscosity and cracks in the film. If the fine particle / polyimide mass ratio or volume ratio is equal to or higher than the lower limit when a dry film is formed, pores having an appropriate density as the porous film can be obtained. It is possible to form a film stably without causing problems such as cracks inside. When the resin material is polyamide-imide or polyamide instead of polyamic acid or polyimide, the mass ratio is the same as above.

Hereinafter, the preferred resin material, fine particles and solvent constituting the coating liquid L will be specifically described.
<Polyamide acid>
As the polyamic acid, those obtained by polymerizing an arbitrary tetracarboxylic dianhydride and a diamine can be used without any particular limitation. Although the usage-amount of tetracarboxylic dianhydride and diamine is not specifically limited, It is preferable to use 0.50-1.50 mol of diamine with respect to 1 mol of tetracarboxylic dianhydrides, and 0.60-1. It is more preferable to use 30 mol, and it is particularly preferable to use 0.70 to 1.20 mol.

  The tetracarboxylic dianhydride can be appropriately selected from tetracarboxylic dianhydrides conventionally used as raw materials for synthesizing polyamic acid. The tetracarboxylic dianhydride may be an aromatic tetracarboxylic dianhydride or an aliphatic tetracarboxylic dianhydride. From the viewpoint of the heat resistance of the resulting polyimide resin, the aromatic tetracarboxylic dianhydride may be used. Preference is given to using carboxylic dianhydrides. Tetracarboxylic dianhydride may be used in combination of two or more.

  Preferable specific examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxy). Phenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′- Biphenyltetracarboxylic dianhydride, 2,2,6,6-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2 , 3-Dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2 -Bis (2,3-dicarboxy Enyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) Ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 4,4- (p-phenylenedioxy) diphthal Acid dianhydride, 4,4- (m-phenylenedioxy) diphthalic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid di Anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride , 2, 3 6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 9,9-bisphthalic anhydride fluorene, 3,3 ′, 4,4′-diphenylsulfone Tetracarboxylic dianhydride etc. are mentioned. Examples of the aliphatic tetracarboxylic dianhydride include ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, 1, 2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, and the like. Among these, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferable from the viewpoint of price and availability. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The diamine can be appropriately selected from diamines conventionally used as a raw material for synthesizing polyamic acid. The diamine may be an aromatic diamine or an aliphatic diamine, but an aromatic diamine is preferred from the viewpoint of the heat resistance of the resulting polyimide resin. These diamines may be used in combination of two or more.

  Examples of the aromatic diamine include diamino compounds in which one phenyl group or about 2 to 10 phenyl groups are bonded. Specifically, phenylenediamine and derivatives thereof, diaminobiphenyl compounds and derivatives thereof, diaminodiphenyl compounds and derivatives thereof, diaminotriphenyl compounds and derivatives thereof, diaminonaphthalene and derivatives thereof, aminophenylaminoindane and derivatives thereof, diaminotetraphenyl Compounds and derivatives thereof, diaminohexaphenyl compounds and derivatives thereof, and cardo-type fluorenediamine derivatives.

  Phenylenediamine is m-phenylenediamine, p-phenylenediamine, etc., and phenylenediamine derivatives include diamines to which alkyl groups such as methyl group and ethyl group are bonded, such as 2,4-diaminotoluene, 2,4-triphenylene. Diamines and the like.

  The diaminobiphenyl compound is a compound in which two aminophenyl groups are bonded to each other. For example, 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, and the like.

  The diaminodiphenyl compound is a compound in which two aminophenyl groups are bonded to each other via other groups. The bond is an ether bond, a sulfonyl bond, a thioether bond, a bond by alkylene or a derivative group thereof, an imino bond, an azo bond, a phosphine oxide bond, an amide bond, a ureylene bond, or the like. The alkylene bond has about 1 to 6 carbon atoms, and the derivative group has one or more hydrogen atoms in the alkylene group substituted with halogen atoms or the like.

  Examples of diaminodiphenyl compounds include 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ketone 3,4′-diaminodiphenyl ketone, 2,2-bis (p-aminophenyl) propane, 2,2′-bis (p-aminophenyl) hexafluoropropane, 4-methyl-2,4-bis ( p-aminophenyl) -1-pentene, 4-methyl-2 4-bis (p-aminophenyl) -2-pentene, iminodianiline, 4-methyl-2,4-bis (p-aminophenyl) pentane, bis (p-aminophenyl) phosphine oxide, 4,4 ′ -Diaminoazobenzene, 4,4'-diaminodiphenylurea, 4,4'-diaminodiphenylamide, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl ] Sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophen ) Phenyl] hexafluoropropane, and the like.

  Among these, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, and 4,4'-diaminodiphenyl ether are preferable from the viewpoint of price and availability.

  In the diaminotriphenyl compound, two aminophenyl groups and one phenylene group are both bonded via other groups, and the other groups are the same as those of the diaminodiphenyl compound. Examples of diaminotriphenyl compounds include 1,3-bis (m-aminophenoxy) benzene, 1,3-bis (p-aminophenoxy) benzene, 1,4-bis (p-aminophenoxy) benzene, and the like. be able to.

  Examples of diaminonaphthalene include 1,5-diaminonaphthalene and 2,6-diaminonaphthalene.

  Examples of aminophenylaminoindane include 5 or 6-amino-1- (p-aminophenyl) -1,3,3-trimethylindane.

  Examples of diaminotetraphenyl compounds include 4,4′-bis (p-aminophenoxy) biphenyl, 2,2′-bis [p- (p′-aminophenoxy) phenyl] propane, 2,2′-bis [ p- (p′-aminophenoxy) biphenyl] propane, 2,2′-bis [p- (m-aminophenoxy) phenyl] benzophenone, and the like.

  Examples of the cardo type fluoreneamine derivative include 9,9-bisaniline fluorene.

  The aliphatic diamine has, for example, about 2 to 15 carbon atoms, and specific examples include pentamethylenediamine, hexamethylenediamine, and heptamethylenediamine.

  A compound in which the hydrogen atom of these diamines is substituted with at least one substituent selected from the group such as a halogen atom, a methyl group, a methoxy group, a cyano group, and a phenyl group may be used.

  There is no restriction | limiting in particular in the means to manufacture the polyamic acid used by this embodiment, For example, well-known methods, such as the method of making an acid and a diamine component react in an organic solvent, can be used.

  Reaction of tetracarboxylic dianhydride and diamine is normally performed in an organic solvent. The organic solvent used for the reaction of the tetracarboxylic dianhydride and the diamine is particularly capable of dissolving the tetracarboxylic dianhydride and the diamine and not reacting with the tetracarboxylic dianhydride and the diamine. It is not limited. An organic solvent can be used individually or in mixture of 2 or more types.

  Examples of the organic solvent used for the reaction of tetracarboxylic dianhydride and diamine include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N Nitrogen-containing polar solvents such as N, N-diethylformamide, N-methylcaprolactam, N, N, N ′, N′-tetramethylurea; β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone Lactone polar solvents such as γ-caprolactone and ε-caprolactone; dimethyl sulfoxide; acetonitrile; fatty acid esters such as ethyl lactate and butyl lactate; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dioxane, tetrahydrofuran, methyl cellosolve acetate, ethyl Ethers such as cellosolve acetate; include phenolic solvents cresols, and the like. These organic solvents can be used alone or in admixture of two or more. Although there is no restriction | limiting in particular in the usage-amount of an organic solvent, It is desirable for content of the polyamic acid to produce | generate to be 5-50 mass%.

  Among these organic solvents, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N- Nitrogen-containing polar solvents such as diethylformamide, N-methylcaprolactam, N, N, N ′, N′-tetramethylurea are preferred.

  The polymerization temperature is generally -10 to 120 ° C, preferably 5 to 60 ° C. The polymerization time varies depending on the raw material composition to be used, but is usually 3 to 24 Hr (hour). Moreover, the intrinsic viscosity of the organic solvent solution of polyamic acid obtained under such conditions is preferably in the range of 1000 to 100,000 cP (centipoise), and more preferably in the range of 5,000 to 70,000 cP.

<Polyimide>
The polyimide used in the present embodiment is not limited to its structure and molecular weight, and any known polyimide can be used as long as it is a soluble polyimide that can be dissolved in the organic solvent used in the coating liquid L. About a polyimide, you may have a functional group which accelerates | stimulates a crosslinking reaction etc. at the time of baking, or a functional group which can be condensed, such as a carboxy group.

  Use of a monomer to introduce a flexible bending structure into the main chain in order to obtain a polyimide soluble in an organic solvent, such as ethylenediamine, hexamethylenediamine, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, Aliphatic diamines such as 4,4′-diaminodicyclohexylmethane; 2-methyl-1,4-phenylenediamine, o-tolidine, m-tolidine, 3,3′-dimethoxybenzidine, 4,4′-diaminobenzanilide, etc. Aromatic diamines; polyoxyalkylene diamines such as polyoxyethylene diamine, polyoxypropylene diamine, and polyoxybutylene diamine; polysiloxane diamines; 2,3,3 ′, 4′-oxydiphthalic anhydride, 3,4,3 ′ , 4′-oxydiphthalic anhydride, 2,2-bis (4-H Rokishifeniru) propane dibenzoate-3,3 ', use of such 4,4'-tetracarboxylic dianhydride is valid. In addition, use of a monomer having a functional group that improves solubility in an organic solvent, for example, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 2-trifluoromethyl-1,4 -It is also effective to use a fluorinated diamine such as phenylenediamine. Furthermore, in addition to the monomer for improving the solubility of the polyimide, the same monomers as those described in the column for the polyamic acid can be used in combination as long as the solubility is not inhibited.

  There is no particular limitation on the means for producing a polyimide that can be dissolved in an organic solvent used in the present embodiment. For example, a known method such as a method in which polyamic acid is chemically imidized or heated imidized and dissolved in an organic solvent is used. Can be used. Examples of such polyimide include aliphatic polyimide (total aliphatic polyimide), aromatic polyimide and the like, and aromatic polyimide is preferable. The aromatic polyimide is obtained by thermally or chemically obtaining a polyamic acid having a repeating unit represented by the formula (1) by a ring-closing reaction or by dissolving a polyimide having a repeating unit represented by the formula (2) in a solvent. Good. In the formula, Ar represents an aryl group.

<Polyamideimide>
As the polyamideimide used in the present embodiment, any known polyamideimide can be used as long as it is a soluble polyamideimide that can be dissolved in the organic solvent used in the coating liquid L without being limited to its structure and molecular weight. The polyamideimide may have a functional group capable of condensing such as a carboxy group in the side chain or a functional group that promotes a crosslinking reaction or the like during firing.

  The polyamideimide used in the present embodiment is obtained by reacting any trimellitic anhydride and diisocyanate, or a precursor polymer obtained by reacting any reactive derivative of trimellitic anhydride with diamine. What is obtained by forming can be used without particular limitation.

  Examples of the arbitrary trimellitic anhydride and acid or a reactive derivative thereof include trimellitic anhydride halides such as trimellitic anhydride and trimellitic anhydride chloride, trimellitic anhydride ester, and the like.

  Examples of the diisocyanate include metaphenylene diisocyanate, p-phenylene diisocyanate, 4,4′-oxybis (phenylisocyanate), 4,4′-diisocyanatediphenylmethane, bis [4- (4-isocyanatophenoxy) phenyl] sulfone, 2, And 2'-bis [4- (4-isocyanatophenoxy) phenyl] propane.

  Examples of the diamine include those similar to those exemplified in the description of the polyamic acid.

<Polyamide>
As the polyamide, a polyamide obtained from a dicarboxylic acid and a diamine is preferable, and an aromatic polyamide is particularly preferable.

  Dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, phthalic acid, isophthalic acid, terephthalic acid, and diphenic acid Etc.

  Examples of the diamine include those similar to those exemplified in the description of the polyamic acid.

<Fine particles>
For example, fine particles having a high sphericity rate are used. Such fine particles are preferable in that they can easily form a curved surface on the inner surface of the pores in the porous membrane. The particle size (average diameter) of the fine particles can be set to about 100 to 2000 nm, for example. By using the fine particles as described above, it is possible to obtain a porous film having a spherical shape or a void having a continuous shape of spherical shapes by removing the fine particles in a subsequent step. Moreover, the pore diameter of the obtained porous membrane can be made uniform. For this reason, characteristics can be made uniform in the porous membrane 2.

The material of the fine particles is not particularly limited as long as it is a material that is insoluble in the solvent contained in the coating liquid L and can be removed from the porous film 2 in a later step. can do. For example, the inorganic materials, silica (silicon dioxide), metal oxides such as titanium oxide, alumina _(Al 2 _{O 3)} can be mentioned. Examples of organic materials include high molecular weight olefins (polypropylene, polyethylene, etc.), polystyrene, epoxy resin, cellulose, polyvinyl alcohol, polyvinyl butyral, polyester, polymethyl methacrylate, polyether, and other organic polymer fine particles. Examples of the fine particles include colloidal silica such as (monodispersed) spherical silica particles, calcium carbonate, and the like. In this case, the pore diameter of the porous membrane 2 can be made more uniform. The fine particles contained in the coating liquid L have a particle size of, for example, 100 to 2000 nm.

<Solvent>
The solvent is not particularly limited as long as it dissolves polyamic acid, polyimide, polyamideimide or polyamide, and a known solvent can be used. Examples of the solvent include N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N, N, N ′, N′-tetramethylurea, N— Nitrogen-containing polar solvents such as vinyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; acetonitrile; fatty acid esters such as ethyl lactate and butyl lactate; tetrahydrofuran, dioxane, dioxolane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, methyl cellosolve acetate And ethers such as ethyl cellosolve acetate. Among these, 1 type may be used and 2 or more types may be used together.

  Further, the solvent can contain a high boiling point solvent having a boiling point of 190 ° C. or higher in addition to the above-mentioned solvent. Examples of the high boiling point solvent include nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone; γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε- Examples include lactone polar solvents such as caprolactone; phenol solvents such as pyrrolidonephenol, o-, m- or p-cresol, xylenol, and catechol; and sulfoxide solvents such as diethyl sulfoxide. As the high boiling point solvent, one of these may be used, or two or more may be used in combination.

  The content ratio of the high boiling point solvent in the solvent is not particularly limited, and a wide range of solvents can be used. In the solvent, the high boiling point solvent is preferably 5 to 80% by mass, more preferably 7 to 70% by mass, and most preferably the high boiling point solvent is 10 to 60% by mass. If the high-boiling solvent is contained in an amount of 5% by mass or more, there is no problem in the film formability and film properties of the porous polyimide film, and if it is 80% by mass or less, the coating and prebaking steps can be performed without any trouble.

  The coating liquid L contains a predetermined resin material, fine particles, a solvent, and various additives such as a release agent, a dispersant, a condensing agent, an imidizing agent, and a surfactant as necessary. You may go out.

  In step S11, as shown in FIG. 4A, the coating liquid L is applied onto the substrate S, and the solvent is removed by drying to form a dry film D. The coating liquid L includes fine particles B. The coating liquid L applied on the substrate S is treated at 50 to 100 ° C. under normal pressure or vacuum (prebaked) to obtain a dry film D. The base material S is not specifically limited, Arbitrary things can be used. For example, a foil may be used as the substrate S. This foil may be used as the conductive film 4. As the foil, for example, metal foil, particularly copper foil and aluminum foil are preferably used. When the porous film 2 is manufactured using the metal foil for the base material S, the metal foil may be retained or only a part of the metal foil may be removed by etching or the like. In these cases, the metal foil can be an electrode and a circuit.

  Subsequently, the dried film D after the pre-bake treatment is peeled off from the base material S as shown in FIG. The peeling method is not particularly limited, and may be performed automatically using a manipulator or the like, or may be performed manually. Next, the peeled dry film D is fired. In addition, in order to suppress that curl generate | occur | produces in the dry film | membrane D before baking, you may perform the immersion process to a solvent containing water, and a press process arbitrarily. Moreover, you may provide the drying process after the said immersion process arbitrarily. A baking temperature is about 120-400 degreeC, for example, and the temperature of about 150-350 degreeC is preferable. Further, when the organic material is contained in the fine particles B, it is necessary to set the temperature lower than the thermal decomposition temperature. In addition, when the coating liquid L contains a polyamic acid, it is preferable to complete imidation in this baking, but this is not the case when the dry film is composed of polyimide, polyamideimide, or polyamide. Whether or not the dried film D is peeled off from the substrate S is determined as appropriate depending on the manufacturing method and the like. For example, when the non-porous film 3 or the conductive film 4 is used as the substrate S as described later, the dry film D does not have to be peeled from the substrate S.

  Next, in step S12 shown in FIG. 3, the porous film 2 is manufactured by removing the fine particles B from the dried film D after firing. For example, when silica is employed as the fine particles B, the dry film can be made porous by dissolving and removing the silica with a low concentration of hydrogen fluoride water (HF) or the like. Further, when the fine particles are resin fine particles, the resin fine particles can be removed by heating to a temperature not lower than the thermal decomposition temperature of the resin fine particles as described above and lower than the thermal decomposition temperature of the polyimide. As shown in FIG. 4C, the portions where the fine particles B are removed from the dry film D become the holes 6, respectively, and the porous film 2 having the voids 5 is formed by the communication of the holes 6. The porous membrane 2 has a uniform porosity in the plane direction (X direction and Y direction). The porous film 2 may contain fine particles B. In this case, the fine particles B may function as a filler to impart strength to the porous film 2.

  Next, in step S <b> 13 shown in FIG. 3, an etching (chemical etching) process is performed on the porous film 2. As shown in FIG. 5A, the porous film 2 is immersed in the etching solution ES, and a part of the resin in the gap 5 is removed. As the etching solution ES, a chemical etching solution such as an inorganic alkali solution or an organic alkali solution is used. Examples of inorganic alkaline solutions include hydrazine solutions containing hydrazine hydrate and ethylenediamine, solutions of alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia solutions, alkali hydroxides And hydrazine and 1,3-dimethyl-2-imidazolidinone as etching components. Organic alkaline solutions include primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; dimethylethanolamine And alcohol amines such as triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and alkaline solutions such as cyclic amines such as pyrrole and pihelidine. By the etching process, as shown in FIG. 5B, protrusions such as burrs in the gap 5 are removed, and at least the porosity of the porous film 2 can be increased. Thereby, the communication property of the space | gap 5 improves, For example, when using the porous film 2 after such an etching as the laminated body 1, a transmission loss can be reduced.

  Thereafter, the porous membrane 2 is washed with a washing liquid and drained. Subsequently, the porous membrane 2 after draining is heated to, for example, about 100 to 400 ° C. (preferably about 100 to 300 ° C.), and the cleaning liquid is removed. In addition, the porous film 2 after the etching may be wound up by a winding device (not shown) to form a roll body (not shown). Moreover, according to the intended purpose, this roll body can adjust the size of a roll body by pulling out the porous film 2, cut | disconnecting with a cutting device, and winding up again to make a roll body. The porous film 2 may be stored after the etching process. When storing the porous film 2 after the etching treatment, the porous film 2 may be stored in the state of a roll body. In addition, the storage conditions (eg, storage time, temperature, humidity) of the porous membrane 2 are arbitrary. Whether or not the etching process is performed in step S13 is arbitrary, and the etching process may not be performed.

  Next, in step S <b> 2 shown in FIG. 2, as shown in FIG. 6A, the liquid LA that becomes the nonporous film 3 is applied to at least one surface of the porous film 2. The non-porous film 3 is, for example, an adhesive that bonds the porous film 2 and the conductive film 4 together. The non-porous film 3 is not particularly limited and is formed of a known resin material. The non-porous membrane 3 is, for example, a resin containing at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone. It is formed by. Especially, it is preferable that the non-porous film 3 is formed of an imide resin containing at least one of polyamic acid, polyimide, polyamideimide, and polyamide. Moreover, it is preferable that the non-porous film 3 and the porous film 2 are formed of the same material, for example.

  As the liquid LA that becomes the non-porous film 3, for example, a liquid in which a resin component is dissolved in a solvent can be used. The liquid LA that becomes the non-porous film 3 is appropriately set according to the resin component and the like. For example, when the non-porous film 3 is formed of the resin, the liquid LA used as the non-porous film 3 is a liquid obtained by removing fine particles from the components of the coating liquid L described in the porous film 2 portion. it can.

  The liquid LA that becomes the non-porous film 3 is preferably applied so that the surface on which the conductive film 4 is applied is a flat surface. In this case, the adhesion between the conductive film 4 and the non-porous film 3 is improved. In this case, since the conductive film 4 becomes flat, the stacked body 1 can be suitably used for a wiring board and a wiring board.

  Next, in step S3 shown in FIG. 2, as shown in FIG. 6B, a previously formed conductive film 4 is pasted. In this case, for example, the conductive film 4 is attached before the liquid LA that becomes the non-porous film 3 is dried. The conductive film 4 is not particularly limited, and any conductive material can be used. For the conductive film 4, for example, a metal foil such as a copper foil, a stainless steel stay, an aluminum stay, or a nickel stay is used. Further, the surface of the conductive film 4 may be subjected to roughening treatment or rust prevention treatment. The thickness of the conductive film 4 is not particularly limited, and can be, for example, about 0.1 μm to 100 μm, preferably 1 μm to 50 μm, more preferably 5 μm to 20 μm.

  In addition, the method of sticking (lamination | stacking) of the electrically conductive film 4 is not restrict | limited to the said method. For example, the method of attaching (lamination) the conductive film 4 may be a method of attaching the conductive film 4 directly to the surface of the non-porous film 3 or the porous film 2 as described later, or a non-porous film. The liquid LA or the liquid L that becomes the porous film 2 may be applied to the conductive film 4 and dried by applying it.

  Next, in step S <b> 4 shown in FIG. 2, as shown in FIG. 6C, the liquid LA that becomes the nonporous film 3 is dried, and the conductive film 4 is bonded to the porous film 2. Thereby, the conductive film 4 is laminated on the porous film 2. The method of drying the liquid LA that becomes the non-porous membrane 3 is appropriately set depending on the resin component and the like. For example, when the non-porous film 3 is formed of the resin, the dry film is formed by pre-baking the liquid LA that becomes the applied non-porous film 3. Thereby, the conductive film 4 is bonded to the porous film 2. Subsequently, when the resin is a polyimide precursor such as polyamic acid, the imidization reaction of the dry film is performed by firing. Thereby, the laminated body 1 shown to FIG. 1 (A) can be obtained. A dry film formed by pre-baking the liquid LA that becomes the non-porous film 3 is included in the non-porous film 3.

  Next, another example of the method for manufacturing a laminate will be described. FIG. 7A is a flowchart illustrating another example of a method for manufacturing a laminate, and FIG. 7B is a cross-sectional view illustrating another example of the method for manufacturing a laminate.

  In this manufacturing method, after forming the non-porous film 3 on at least one surface of the porous film 2, the conductive film 4 is laminated on the formed non-porous film 3. That is, this is a method in which the non-porous film 3 is not used as an adhesive. In the present manufacturing method, as shown in FIG. 7A, first, the porous film 2 is obtained by performing the above-described step S1.

  Subsequently, in step S5 shown in FIG. 7 (A), as shown in FIG. 7 (B), the liquid LA to be a non-porous film is applied to the porous film 2 and dried to thereby form the non-porous film 3. Form. The liquid LA that becomes the non-porous film is the same as that in step S2. The method for drying the liquid LA that becomes the non-porous membrane 3 is the same as that in step S4, and is appropriately set depending on the resin component and the like. For example, when the non-porous film 3 is formed of the above resin, the non-porous film 3 (dry film) is formed by pre-baking the liquid LA that becomes the applied non-porous film 3, and the resin is formed of polyamic acid or the like. In the case of a polyimide precursor, an imidization reaction is performed by firing this dry film. At this time, the non-porous film 3 is preferably formed so that the surface to which the conductive film 4 is attached is a flat surface. In this case, the adhesion between the conductive film 4 and the non-porous film 3 is improved. In this case, since the conductive film 4 becomes flat, the stacked body 1 can be suitably used for a wiring board and a wiring board.

  Subsequently, in step S6 shown in FIG. 7A, the conductive film 4 is stacked. For example, the conductive film 4 is directly laminated on the surface of the nonporous film 3. For example, the conductive film 4 is laminated by thermocompression bonding. Thereby, the laminated body 1 shown in FIG.6 (C) can be obtained.

  Next, another example of the method for manufacturing a laminate will be described. FIG. 8A is a flowchart illustrating another example of a method for manufacturing a laminate, and FIG. 8B is a cross-sectional view illustrating another example of the method for manufacturing a laminate.

  This manufacturing method is a method of laminating a porous film 2 and a non-porous film 3 that are separately manufactured. In this manufacturing method, as shown in FIG. 8A, first, the above-described step S1 is performed to obtain the porous membrane 2.

  Subsequently, in step S7 shown in FIG. 8A, as shown in FIG. 8B, the non-porous membrane 3 is formed by applying the liquid LA to be the non-porous membrane to the substrate S and drying it. Form. First, a liquid LA that becomes a non-porous film is applied. The liquid LA that becomes the non-porous film is the same as in step S2. Subsequently, the liquid LA that becomes the non-porous film 3 is dried. Thereby, the non-porous film 3 is formed. The method for drying the liquid LA that becomes the non-porous membrane 3 is the same as in step S4. Whether or not step S7 is performed is arbitrary. For example, when using a non-porous membrane 3 formed in advance, such as a commercial product, step S7 need not be performed.

  Subsequently, in step S <b> 8 shown in FIG. 8A, the previously formed non-porous film 3 is laminated on at least one surface of the porous film 2. Thereby, the composite film 7 in which the non-porous film 3 is laminated on at least one surface of the porous film 2 shown in FIG. 7B is formed. The method for stacking the porous film 2 and the non-porous film 3 is not particularly limited. For example, the method of laminating the porous film 2 and the non-porous film 3 may be pressure bonding, welding, a method of laminating by sintering, or a method of adhering with an adhesive. As the adhesive in this case, the liquid LA that becomes the above-described non-porous film can be used.

  Subsequently, as shown in FIG. 8A, in step S6 described above, the conductive film 4 is laminated. Thereby, the laminated body 1 shown in FIG.6 (C) can be obtained.

  Note that the conductive film 4 may be used as the base material S in step S7 shown in FIG. Thereby, the composite body 8 of the nonporous film 3 and the conductive film 4 in which the conductive film 4 is laminated on one surface of the nonporous film 3 shown in FIG. 8D is formed. In this case, step S6 shown in FIG. 8A can be omitted, and the method for manufacturing the laminate 1 can be simplified.

  As described above, the laminates 1 and 1A according to the present embodiment have low transmission loss. Moreover, the manufacturing method of the laminated body which concerns on this embodiment can manufacture suitably the laminated body 1 and 1A with few transmission losses.

[Second Embodiment]
A second embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  As shown in FIG. 9A, the laminate 1B of the present embodiment includes a porous film 2a and a non-porous film 3. The porous film 2a is formed by laminating a plurality of porous layers (porous layer 9 and porous layer 10) having different porosity. When the porous membrane 2a has a plurality of porous layers, various functions (characteristics) can be imparted and the strength can be improved. The porous film 2a has two layers, but may be formed of three or more porous layers.

  The porous layer 9 has a plurality of voids 5a. The porous layer 10 has a plurality of voids 5b. For example, the inner diameter of the gap 5a is smaller than the inner diameter of the gap 5b. The inner diameter of the gap 5a may be larger than the inner diameter of the gap 5b, and the inner diameter of the gap 5a may be the same as the inner diameter of the gap 5b. The shape of the gap 5 a and the shape of the gap 5 b are spherical or a shape in which spherical shapes are continuous, and are the same as the gap 5.

  The porosity of the porous layer 9 and the porosity of the porous layer 10 are, for example, 45% or more and 80% or less, respectively. When the porosity of the porous layer 9 and the porosity of the porous layer 10 are each in the above ranges, a laminate 1B having a lower transmission loss can be obtained. The porosity of the porous layer 9 may be higher than the porosity of the porous layer 10 or may be lower than the porosity of the porous layer 10.

  The film thickness of the porous layer 9 and the film thickness of the porous layer 10 are not particularly limited, but are preferably 1 μm or more and 240 μm or less, respectively. When the film thickness of the porous layer 9 and the film thickness of the porous layer 10 are respectively in the above ranges, the film has excellent strength and can suppress film elongation, wrinkles, pinholes, and film breakage during processing. The laminate 1 can be obtained with little transmission loss. The film thickness of the porous film 2a is the same as that of the porous film 2 of the first embodiment.

  The forming material of the porous layer 9 and the porous layer 10 is the same as that of the porous film 2 of the first embodiment. In the example of this embodiment, the porous layer 9 and the porous layer 10 are formed of the same material. When the porous layer 9 and the porous layer 10 are formed of the same material, the adhesion between the porous layer 9 and the porous layer 10 is further improved. Further, in this case, the heat resistance can be improved, and the type of the material of the laminated body 1B can be reduced, so that the production of the laminated body 1B can be simplified. Note that the porous layer 9 and the porous layer 10 may be formed of different materials.

  The relative dielectric constant of the porous film 2a at a frequency of 1 GHz is, for example, 2.0 or less, preferably 1.8 or less, and more preferably 1.6 or less. The relative dielectric constant of the porous film 2a at a frequency of 10 GHz is, for example, 2.0 or less, preferably 1.8 or less, more preferably 1.6 or less. When the relative dielectric constant of the porous film 2a is in the above range, the transmission loss can be further reduced.

  The conductive film 4 is the same as that of the first embodiment. The conductive film 4 is laminated on at least one surface of the porous film 2a. The conductive film 4 is laminated on, for example, the upper surface (the surface on the + Z side) of the porous film 2a. For example, the conductive film 4 is laminated on the upper surface of the porous film 2 via the non-porous film 3. As shown in FIG. 9B, the conductive film 4 may be laminated on both surfaces (the + Z side surface and the −Z side surface) of the porous film 2a.

  The non-porous membrane 3 is the same as in the first embodiment. The non-porous film 3 is disposed between the porous film 2 a and the conductive film 4. For example, the conductive film 4 and the non-porous film 3 are formed on a flat surface. In this case, the adhesion between the conductive film 4 and the nonporous film 3 is further improved. The non-porous film 3 is laminated on at least one surface of the porous film 2a, for example. The non-porous film 3 is laminated on the upper surface of the porous layer 9, for example. The non-porous film 3 may be stacked on the porous layer 10 or may be stacked on both surfaces of the porous film 2a as in a stacked body 1C shown in FIG. 9B. When the non-porous film 3 is laminated on both surfaces of the porous film 2a, the conductive film 4 may not be provided on both surfaces of the porous film 2a. For example, one surface of the porous film 2a May be provided.

  FIG. 10 is a flowchart showing an example of a method for producing the porous membrane 2a. FIG. 11 is a cross-sectional view showing a method for manufacturing the porous membrane 2a. For example, as shown in FIG. 10, the porous membrane 2a is manufactured by applying a liquid of the resin (imide-based resin) containing the fine particles B on the substrate S and drying it in step S11 described above. A film D is formed. At this time, the drying for forming the dry film D from the coating liquid L only needs to remove the solvent and form the dry film D, for example. For example, the pre-baking and baking described in step S11 may be performed later.

  Subsequently, in step S14 shown in FIG. 10, as shown in FIG. 11A, by applying the liquid LB of the resin (imide resin) containing the fine particles B to the dry film D and drying, A dry film DA shown in FIG. 11B is formed. Thereby, the dry film DA is laminated on the dry film D. Drying when forming the dry film DA is performed, for example, by the above-described pre-baking and baking. In this case, since the imidization of the dry film D and the dry film DA can be performed at a time, the production can be simplified.

  Subsequently, in step S12 described above, the fine particles B are removed. For example, the dry film D and the dry film DA are treated with hydrogen fluoride water (HF) at a time. Thereby, the fine particles B are removed from the dry film D and the dry film DA, and the porous film 2a shown in FIG. 9 can be obtained. In this case, since the fine particles B can be removed from the dry film D and the dry film DA at once, the manufacturing can be simplified.

  Subsequently, in the above-described step S13, an etching process is performed. Thereby, the porosity of the porous membrane 2a can be increased. Whether or not step S13 is performed is arbitrary.

  As described above, the laminates 1 </ b> B and 1 </ b> C of this embodiment have high strength and can have various functions (characteristics).

[Third Embodiment]
A third embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. FIG. 12A is a diagram illustrating an example of a laminated body according to the third embodiment, and FIGS. 12B and 12C illustrate other examples of the laminated body according to the third embodiment. It is sectional drawing.

  As shown in FIG. 12A, the stacked body 1D of the present embodiment includes, for example, a porous film 2 and a conductive film 4. In the laminate 1D of the present embodiment, the porous film 2 and the conductive film 4 are directly laminated. The porous film 2 and the conductive film 4 are the same as in the first embodiment. Since the laminated body 1D of the present embodiment includes the porous film 2, the transmission loss is small.

  The conductive film 4 is laminated on at least one surface of the porous film 2. The conductive film 4 is laminated, for example, on the upper surface (+ Z side surface) of the porous film 2. In addition, the electrically conductive film 4 may be laminated | stacked on both surfaces of the porous film 2, like the laminated body 1E shown to FIG. 12 (B). In addition, the conductive film 4 may be stacked on at least one surface of the porous film 2a having a plurality of layers having different porosity, like a stacked body 1F shown in FIG.

  The method for laminating the porous film 2 and the conductive film 4 is not limited. For example, in the method of laminating the porous film 2 and the conductive film 4, the liquid L (coating liquid L) that becomes a porous film is applied to the conductive film 4 and dried to dry the porous film 2 and the conductive film 4. Alternatively, the porous film 2 and the conductive film 4 formed separately may be laminated by thermocompression bonding or the like.

  FIG. 13A is a flowchart showing a method for manufacturing the stacked body 1D. FIG. 13B is a cross-sectional view illustrating the method for manufacturing the stacked body 1D.

  In the manufacture of the stacked body 1D, for example, the porous film 2 is formed on the conductive film 4, and the porous film 2 and the conductive film 4 are stacked. In this case, in step S15 shown in FIG. 13A, the liquid L (coating liquid L) of the resin (imide-based resin) containing the fine particles B is applied to the conductive film 4 and dried to dry the film. D is formed. For example, the coating liquid L is applied to the conductive film 4 as shown in FIG. Subsequently, the conductive film 4 to which the coating liquid L is applied is pre-baked and baked in the same manner as in step S1, thereby forming a dry film D shown in FIG. Thereby, the conductive film 4 and the dry film D are laminated.

  Subsequently, as shown in FIG. 13A, in the above-described step S12, the fine particles B are removed to form the porous film 2. Thereby, the porous film 2 and the conductive film 4 are laminated, and a laminate 1D shown in FIG. 12A is obtained.

  In addition, when the liquid of the said resin (imide resin) is apply | coated to the electrically conductive film 4, and fine particle B is removed after that like step S15 and step S12 shown to FIG. If an HF solution is used when silica (fine particles B) are dissolved (removed), the HF solution may damage the conductive film 4 depending on the material of the conductive film 4. As a means for avoiding such damage to the conductive film 4 by the HF solution, for example, a corrosion-resistant alloy having corrosion resistance to the HF solution such as Hastelloy (registered trademark) may be used as the material for forming the conductive film 4. Further, for example, the material for forming the fine particles B is heated using an organic polymer such as high molecular weight olefin (polypropylene, polyethylene, etc.), polystyrene, epoxy resin, cellulose, polyvinyl alcohol, polyvinyl butyral, polyester, polymethyl methacrylate, polyether, etc. The fine particles B may be removed without using the HF solution by removing the fine particles B by being decomposed by the treatment. In this case, for example, when the porous film 2 is a polyimide resin, the heat treatment may be combined with the heat treatment for imidization. Alternatively, the fine particles B formed from polymethyl methacrylate may be depolymerized by irradiating UV light of 172 nm and then dissolved in a solvent such as 2-propanol. In this case, since the fine particles B can be removed without heat treatment, the resin is composed of polyamideimide, polyamide, polyvinylidene fluoride, polysulfone, polyarylsulfone, and polyethersulfone that can be subjected to an optional baking step. It is preferable to use at least one member of the group.

  Subsequently, in step S13, an etching process is performed. Step S13 is as described above. Thereby, at least the porosity of the porous membrane 2 can be increased. Whether or not the etching process is performed in step S13 is arbitrary, and step S13 may not be performed.

  As described above, the laminates 1D, 1E, and 1F of the present embodiment have a small transmission loss.

[Fourth Embodiment]
A fourth embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. FIG. 14 is a cross-sectional view showing an example of a wiring board 12 according to the fourth embodiment.

  In the wiring substrate 12 of the present embodiment, for example, the wiring pattern 13 is formed on at least a part of the conductive film 4 of the laminate 1 described above. Since the wiring board 12 has the laminate 1, the transmission loss is small. The pattern of the wiring pattern 13 is not particularly limited and is arbitrary. The method for forming the wiring pattern 13 is not particularly limited and is arbitrary. For example, the wiring pattern 13 is formed by etching, machining, or the like.

  The wiring board 12 includes any one in which the wiring pattern 13 is formed on at least a part of the conductive film 4 of the above-described laminated bodies 1A, 1B, 1C, 1D, 1E, and 1F instead of the laminated body 1. May be. Further, the wiring substrate 12 may be a multilayer substrate in which any one of the plurality of stacked bodies 1, 1A, 1B, 1C, 1D, 1E, and 1F is used.

  As described above, the wiring board 12 of this embodiment has a small transmission loss.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to these examples.

In the examples, the following tetracarboxylic dianhydrides, diamines, polyamideimides, dispersants, organic solvents, and fine particles were used.
・ Tetracarboxylic dianhydride: pyromellitic dianhydride ・ Diamine: 4,4′-diaminodiphenyl ether ・ Dispersant: Polyoxyethylene secondary alkyl ether dispersant ・ Silica: (average particle size) 300 nm, 700 nm

<Reference Example 1>
(Manufacture of porous membrane)
A porous film in which the first porous layer and the second porous layer were laminated was manufactured by the following method.

[Preparation of Varnish-1]
(1) First varnish (adjustment liquid for the first porous layer)
In a separable flask equipped with a stirrer, a stirring blade, a reflux condenser, and a nitrogen gas inlet tube, 6.5 g of tetracarboxylic dianhydride, 6.7 g of diamine, and 30 g of N, N-dimethylacetamide were charged. . Nitrogen was introduced into the flask through a nitrogen gas introduction tube, and the atmosphere in the flask was changed to a nitrogen atmosphere. Next, while stirring the contents of the flask, tetracarboxylic dianhydride and diamine were reacted at 50 ° C. for 20 hours to obtain a polyamic acid solution. 75 g of silica having an average particle diameter of 300 nm was added to the obtained polyamic acid solution and stirred, so that the volume ratio of polyamic acid to fine particles was 22:78 (mass ratio was 15:85). Was prepared. In addition, it added and adjusted so that the ratio of the total organic solvent in a varnish might be set to 70 mass%, and an organic solvent composition might be set to N: N-dimethylacetamide: gamma butyrolactone = 90: 10.

(2) Second varnish (adjustment liquid for the second porous layer)
The volume ratio of polyamic acid to fine particles was 28:72 (mass ratio was 20:80) in the same manner as (1) except that 53 g of silica having an average particle diameter of 700 nm was added to the obtained polyamic acid solution. A second varnish was prepared.

[Formation of precursor film (polyimide-fine particle composite film)]
The first varnish produced in Preparation 1 of the varnish was applied to a glass plate (base material) coated with a release agent using an applicator and dried to form a dry film. This layer (thickness, about 1 μm) forms the first porous layer. Subsequently, the second varnish produced in the same manner as in Preparation of Varnish-1 was applied onto the first porous layer using an applicator and dried to form a dry film. This layer (thickness, about 24 μm) forms the second porous layer. Prebaked at 70 ° C. for 5 minutes to form an unfired composite film having a film thickness of 25 μm as shown in FIG.

  After peeling off the unfired composite film from the substrate, the release agent was removed with ethanol, and heat treatment was performed at 320 ° C. for 15 minutes to complete imidization to obtain a precursor film (polyimide-fine particle composite film).

[Formation of porous film (porous polyimide film)]
The precursor film (polyimide-fine particle composite film) was immersed in a 10% HF solution for 10 minutes to remove fine particles contained in the film.

[Chemical etching]
A 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) was diluted with a 50 mass% aqueous methanol solution to 1.04% to prepare an alkaline etching solution. A porous polyimide film was immersed in this etching solution to remove a part of the polyimide surface, and a porous film 2a in which the first porous layer and the second porous layer shown in FIG. 9 were laminated was manufactured.

(Measurement of relative permittivity)
The relative dielectric constant of the obtained porous film was measured. The relative dielectric constant of the porous film is measured by using a cavity resonator method apparatus (manufactured by AET Co., Ltd.) and by cavity resonator vibration method at frequencies of 1 GHz and 10 GHz at a temperature of 27 degrees and a humidity of 50%. did. The relative dielectric constant was measured five times, and the average value was calculated as the relative dielectric constant. The results are shown in Table 1.

<Comparative Example 1 and Comparative Example 2>
(Relative permittivity of liquid crystal polymer film)
The relative dielectric constant of the liquid crystal polymer film was used as Comparative Example 1. The relative dielectric constant is shown in Table 1.

(Relative permittivity of non-porous polyimide film)
The relative dielectric constant of the non-porous polyimide film was used as Comparative Example 2. The relative dielectric constant is shown in Table 1.

  The relative dielectric constants used in Comparative Example 1 and Comparative Example 2 are the web pages of Yamaichi Electronics Co., Ltd. (http://www.yamaichi.co.jp/products/tabid/104/Default.aspx), respectively. The catalog value published in is used.

(result)
As shown in Table 1, it is confirmed that the porous film used in the laminate of the present invention has a low relative dielectric constant. From this result, it is confirmed that the laminate of the present invention has a low transmission loss.

  The technical scope of the present invention is not limited to the aspects described in the above-described embodiments. One or more of the requirements described in the above embodiments and the like may be omitted. In addition, the requirements described in the above-described embodiments and the like can be combined as appropriate. In addition, as long as it is permitted by law, the disclosure of all documents cited in the above-described embodiments and the like is incorporated as a part of the description of the text.

DESCRIPTION OF SYMBOLS 1, 1A-1F ... Laminated body, 2 ... Porous film, 3 ... Non-porous film, 4 ... Conductive film 5, 5a, 5b ... Air gap, 12 ... Wiring substrate

Claims (16)

Formed from a resin containing at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone, and spherical or spherical A porous membrane having a plurality of voids in a continuous shape,
And a conductive film laminated on at least one surface of the porous film.   The laminate for a wiring board according to claim 1, comprising a non-porous film between the porous film and the conductive film.   The laminate for a wiring board according to claim 2, wherein the laminate is formed on a flat surface between the conductive film and the non-porous film.   The laminate for a wiring board according to claim 2 or 3, wherein the non-porous film is laminated on both surfaces of the porous film.   The wiring substrate laminate according to any one of claims 2 to 4, wherein the non-porous film is an adhesive that bonds the porous film and the conductive film.   The non-porous film is formed of a resin containing at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone. The laminate for a wiring board according to any one of claims 2 to 5, wherein   The laminate for a wiring board according to claim 6, wherein the porous film and the non-porous film are formed of the same material.   The laminate for a wiring board according to any one of claims 1 to 7, wherein the porous film has a porosity of 45% or more and 90% or less.   The laminate for a wiring board according to any one of claims 1 to 8, wherein the porous film is formed by laminating a plurality of layers having different porosity.   The laminate for a wiring board according to any one of claims 1 to 9, wherein the conductive film is formed on both surfaces of the porous film.   The wiring board by which a wiring pattern is formed in at least one part of the said electrically conductive film of the laminated body for wiring boards as described in any one of Claims 1-10. Forming a porous membrane from a resin containing at least one of polyamic acid, polyimide, polyamideimide, polyamide, polyvinylidene fluoride, polybenzoxazole resin, polybenzimidazole resin, polysulfone, polyarylsulfone, and polyethersulfone; ,
And laminating a conductive film on at least one surface of the porous film.   After applying a liquid which becomes a non-porous film on at least one surface of the porous film, the conductive film is adhered to the porous film by attaching the conductive film and drying the non-porous film. The manufacturing method of the laminated body for wiring boards of Claim 12. The porous film forms a dry film by applying a liquid of the resin containing fine particles to a substrate and drying it;
The method for producing a laminate for a wiring board according to claim 12, comprising removing the fine particles from the dry film to make it porous.   The method for manufacturing a laminate for a wiring board according to claim 14, wherein the conductive film formed in advance is used as the base material. The method for manufacturing a laminate for a wiring board according to claim 14, wherein the fine particles are removed after the conductive film is laminated on the porous film.

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