JP2011194759A - Polyester film for supporting interlayer insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film suitable for a support for interlayer insulating material, to roughen the surface of an interlayer insulating layer and prevent defects of the surface.SOLUTION: The polyester film for supporting an interlayer insulating material can be obtained by co-extrusion process, and includes a coating layer formed on one side of a biaxially oriented laminated polyester film composed of at least three layers. In addition, the polyester film simultaneously satisfies formula (1) SRaA≤15, formula (2) 15≤dT, formula (3) cB≤100 and formula (4) R≤1.0×10. In the formulae, SRaA is the center line average roughness (nm) of the surface on the side opposite to the surface with the coating layer; dT is the thickness (μm) of the film; cB is the amount of particle (ppm) of the average particle diameter of not less than 0.4 μm contained in the intermediate layer; and R is the surface intrinsic resistivity (Ω/Square) of the coating layer surface.

Description

The present invention relates to a support film of an interlayer insulating material, and more particularly to a support film of an interlayer insulating material used for a circuit board. For example, a circuit board configuration such as a printed wiring board, a multilayer wiring board, a semiconductor device, and a liquid crystal display device The present invention provides a support polyester film for an interlayer insulating material suitable as a support film for an interlayer insulating material used for forming an interlayer insulating layer as a member. Here, the support polyester film for an interlayer insulating material is a support film used to apply and dry an interlayer insulating material solution in a film shape in advance, and the obtained film-shaped interlayer insulating material is vacuum-pressed or vacuum-rolled. It is peeled off after being laminated on a circuit board using a laminator.

  A printed wiring board is a board on which a copper circuit is formed in order to mount and connect electronic components such as ICs, such as consumer printed wiring boards used in household appliances such as televisions, computers, measuring instruments, etc. Examples include industrial printed wiring boards used for industrial purposes. Although there is no clear distinction, the printed wiring board base material is mainly used for consumer use, such as those made from paper-based phenolic resin laminates. The used glass cloth base laminate is used as a base for an industrial printed wiring board.

  As the number of terminals such as ICs installed on a printed wiring board increases, multilayering is achieved as means for accommodating necessary wiring in a limited area, and multilayer printed wiring boards are also mass-produced.

  By repeating the process of forming a wiring pattern on a rigid substrate, forming an insulating layer thereon, further forming a wiring pattern thereon, and further forming an insulating layer among the multilayer printed wiring boards, The build-up method for forming printed wiring boards is used as a method suitable for products that require miniaturization, such as mobile phones, and applications that require high-speed operation, such as computers. The build-up layer has been further multi-layered, and the miniaturization and high density of the wiring are further advanced.

  The insulating layer used in the multilayer printed wiring board is made of glass cloth impregnated with epoxy or polyimide resin, or ceramic material. The signal propagation speed of the wiring layer or the printed wiring board Therefore, it is necessary to select a material that satisfies such electrical characteristics. Specifically, a material having a dielectric constant as low as possible is selected. Various proposals have been made. In addition, since the insulating layer is formed on the film support with a uniform thickness, it is preferable to meet the demands for miniaturization and high performance, and a material that can be applied is used. Yes.

  The insulation layer is formed by applying a thermosetting resin as an insulation layer to a film-like support as an interlayer insulation material to cope with downsizing and high performance, and curing the support film with the film. A method has been proposed in which the layers are rolled. With regard to the insulating layer in the film state, it is a film having an insulating layer for buildup that is designed to be suitable for laser processing and to improve the plating adhesion of the resin surface after the roughening treatment, by optimal selection of resin and filler, etc. Various proposals have been made regarding the insulating layer, such as to meet recent demands.

  However, the film, which is a support for forming a film-like insulating layer, has a specific effect in spite of having a great influence on the surface properties of the insulating layer and the productivity when forming the insulating layer. No proposal has been made.

  In particular, in order to achieve finer and higher density wiring, it is necessary to reduce the roughness of the surface of the interlayer insulating layer. On the other hand, when the roughness of the support film is advanced to a high degree, In addition, when used, deterioration of productivity due to defects associated with charging / discharging becomes a problem. Therefore, the properties of the film used for the support are greatly related to the productivity, but no proposal for the support film has been made.

For the miniaturization of wiring, a very narrow wiring width and space of several hundred microns to several microns are required. However, if the roughness of the surface of the interlayer insulating layer is large, the risk of the following problems 1 to 4 increases.
1. Since it is difficult for the plating solution to enter the recess, the supply of reactive species is reduced, and electroless cylinder plating does not occur, so-called non-plating may occur.
2. In the electrolytic copper plating process, voids are formed in the recesses and the treatment liquid remains, which may cause corrosion.
3. In the etching for circuit formation, the etching proceeds from the concave portion under the circuit, the pattern may be thinned, and the remaining circuit may be short-circuited without the copper plating being etched.
4). In order to remove the plating residue (smear) that has entered the recess, a long flash etching is required. If the flash etching is performed for a long time, the fine wiring may be damaged or disconnected.

  Since the film surface serving as the support is rolled up in the form of a roll, protrusions due to the added particles are formed, and these protrusions are transferred to the surface of the interlayer insulating layer to form dents. Therefore, to reduce the roughness of the surface of the interlayer insulating layer, it is necessary to reduce the roughness of the support film.

  However, if the roughness of the support film is made extremely low, static electricity tends to be charged on the support film in the processing process from the forming process of the support film to the application of the interlayer insulating material. It may cause a disaster. In addition, dust, dust, and the like are attracted to the charged support film, and the adhered foreign matter causes defects in the interlayer insulating layer and the wiring circuit.

JP 2005-154727 A JP 2005-39247 A JP 2008-251971 A

  The present invention has been made in view of the above-described circumstances, and the problem to be solved is a suitable interlayer for reducing the roughness of the surface of the interlayer insulating layer and preventing defects in order to cope with the finer and higher density of the wiring. The object is to provide a support polyester film for an insulating material.

  As a result of intensive studies in view of the above-described actual situation, the present inventor has found that the above problem can be easily solved by a polyester film having a specific configuration, and has completed the present invention.

That is, the gist of the present invention is to have a coating layer on one side of a biaxially oriented laminated polyester film comprising at least three layers obtained by a coextrusion method, and simultaneously satisfy the following formulas (1) to (4). The characteristic feature resides in a polyester film supporting an interlayer insulating material.
SRaA ≦ 15 (1)
15 ≦ dT (2)
cB ≦ 100 (3)
R ≦ 1.0 × 10 ¹³ (4)
(In the above formula, SRaA is the center line average roughness (nm) of the surface opposite to the surface having the coating layer, dT is the thickness of the film (μm), cB is the average particle diameter contained in the intermediate layer 0.4 μm) (The above particle amount (ppm), R represents the surface specific resistivity (Ω / □) of the coating layer surface)

  According to the present invention, it is possible to provide a support polyester film for an interlayer insulating material suitable for reducing the roughness of the surface of the interlayer insulating layer and preventing defects in order to cope with finer and higher density wiring. Its industrial value is high.

Hereinafter, the present invention will be described in more detail.
The support for forming the film-like interlayer insulating material of the present invention comprises a biaxially oriented polyester film, and the polyester film is composed of three or four layers by a so-called coextrusion method using three or more melt extruders. It can be set as the laminated film of a layer or more.

  The polyester layers of the polyester film of the present invention need to be adjacent to each other, and raw materials in which the same particles or different particles are blended can be used for the outermost layers serving as the respective surfaces.

  The polyester used for the polyester film in the present invention may be a homopolyester or a copolyester. In the case of a homopolyester, those obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol are preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Representative polyester includes polyethylene terephthalate (PET) and the like. On the other hand, examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acid (eg, P-oxybenzoic acid). 1 type or 2 types or more are mentioned, As a glycol component, 1 type or 2 types or more, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, is mentioned. In any case, the polyester referred to in the present invention refers to a polyester that is polyethylene terephthalate or the like that is usually 60 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, which is an ethylene terephthalate unit.

  In this invention, it is preferable to use the aluminum oxide particle which has a specific particle size and form as a particle | grain mix | blended with a polyester film. That is, in the present invention, it is preferable to use aggregate particles obtained by appropriately agglomerating fine primary particles. In order to obtain a high-strength film, it is necessary to orient strongly at the time of film formation, but in this case, dropout of particles from the film surface and generation of wear powder are often significant. However, in the case of agglomerated particles, the stretching stress at the time of film formation is moderately dispersed, or the particles are unlikely to fall off, and the comparatively rough protrusions are given to the film surface. Give different and favorable friction and wear properties.

  The size of the aggregate is usually 50 to 400 nm, preferably 70 to 300 nm. When this value is less than 50 nm, when the film comes into contact with the roll of the processing machine, the wear resistance of the film becomes slightly inferior. On the other hand, when this value exceeds 400 nm, the cutting blade tends to be chipped when the film is cut, and the slit property tends to be inferior.

  In the present invention, the average particle diameter of the primary particles constituting such an aggregate is usually 5 to 40 nm. When this value is less than 5 nm, the agglomerates often have extremely strong bonds, and the bonds are hardly broken even by stretching stress, and the effects specific to the present invention may not be obtained. On the other hand, when this value exceeds 40 nm, the aggregate particles may be separated and dropped off, which may cause damage.

  The aluminum oxide used in the present invention can be obtained, for example, by heating and baking boehmite, vialite, or gibbsite to about 880 to 1150 ° C. in air or in vacuum. By selecting the conditions at the time of production, for example, the type, crystallinity, particle size, purity of the starting material, or the atmosphere, temperature, and speed during heating, a material having a primary particle size of 5 to 40 nm required in the present invention can be obtained. Although they can, they often form aggregates in excess of 1 μm. Aggregates having an appropriate particle size used in the present invention can be easily obtained, for example, by pulverizing such coarse aggregates.

  For the pulverization treatment, for example, a rod mill, a ball mill, a vibrating rod mill, a vibrating ball mill, a pan mill, a roller mill, an impact mill, a stirring mill, a fluid energy mill, or the like can be used. In addition, if necessary, ultrasonic dispersion treatment may be performed, but if the degree is strong, care is required because the particles are dispersed to the primary particles or a state close thereto. In the present invention, treatments such as classification and filtration may be used in combination.

  In the present invention, one surface of the polyester film requires a specific surface roughness in order to achieve both the surface property of the interlayer insulating layer formed on the polyester film and the prevention of scratch defects on the film. For this purpose, it is preferable to contain particles having an average particle diameter of 0.1 to 0.6 μm, preferably 0.2 to 0.5 μm in the polyester layer on the surface side. If the average particle size is less than 0.1 μm, the surface roughness of the film is low, the film is not slippery and the film surface is liable to be scratched. There is a possibility that it cannot be obtained. Further, when the average particle diameter exceeds 0.6 μm, the dent on the surface of the interlayer insulating layer becomes large, which may adversely affect the miniaturization of the wiring and the high density of the circuit.

  The content of the particles in the polyester layer is usually 100 to 2000 ppm, preferably 200 to 1500 ppm, and more preferably 500 to 1000 ppm. If the particle content is less than 100 ppm, the slipperiness of the film may be deteriorated. Moreover, when content exceeds 2000 ppm, there exists a tendency for the surface roughness of a film to become large too much and for flatness to be impaired.

  Examples of such particles include silicon oxide, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, lithium phosphate, magnesium phosphate, lithium fluoride, aluminum oxide, titanium oxide, kaolin, talc, carbon black, silicon nitride. , Boron nitride, and crosslinked polymer fine powder as described in JP-B-59-5216 are not limited thereto, as long as the gist of the present invention is not impaired.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape and the like may be used. Moreover, there is no restriction | limiting in particular about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be adopted. For example, it can be added at any stage for producing the polyester constituting each layer, but the polycondensation reaction may proceed preferably after the esterification stage or after the transesterification reaction.

  Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  In addition to the above-mentioned particles, conventionally known antioxidants, antistatic agents, thermal stabilizers, lubricants, dyes, pigments, and the like can be added to the polyester film in the present invention as necessary.

  In the present invention, the amount of particles having an average particle size of 0.4 μm or more in the intermediate layer of the polyester film is 100 ppm or less, preferably 50 ppm or less, and more preferably 0 ppm. If it exceeds 100 ppm, waviness occurs on the A side of the polyester film, which is undesirable because it causes problems in miniaturizing the wiring and increasing the density of the circuit.

  One of the features of the present invention is that the polyester film as the support has a specific surface roughness, and the center line average roughness SRaA of the film surface on the side opposite to the surface provided with the coating layer described later is 15 nm. Hereinafter, it is preferably in the range of 0.5 nm to 10 nm. When the center line average roughness SRaA is less than 0.5 nm, the slipperiness of the film and air leakage between the films tend to deteriorate, and the film surface is likely to be damaged. When the center line average roughness SRaA exceeds 15 nm, it is not preferable because it adversely affects wiring miniaturization and circuit density.

  The polyester film itself of the present invention is peeled off after the interlayer insulating layer is bonded to the core substrate as an adhesive sheet, and the role is finished, but the interlayer insulation bonded to the core substrate after the polyester film is peeled off Affects the surface of the layer.

  The thickness of the polyester film of this invention is 15 micrometers or more, Preferably it is the range of 20-50 micrometers. If the film thickness is less than 15 μm, wrinkles will occur when an insulating material is applied, which is not preferable. When the film thickness exceeds 50 μm, the amount of polyester used increases.

The biaxially oriented polyester film in the present invention preferably has a coating layer on one side and contains a cationic polymer in the coating layer, and the surface resistivity of the coating layer is 1 × 10 ¹³ Ω or less. is necessary.

  In the present invention, a polymer antistatic agent is preferable as the antistatic agent used in the coating layer. A low molecular weight antistatic agent is not preferred because the antistatic agent tends to transfer onto the overlapping surface when the film is wound. Among polymer antistatic agents, cationic polymers are generally preferred over nonionic polymers because of their higher antistatic performance. A cationic polymer is more preferable than an anionic polymer due to its handleability.

  The cationic polymer in the coating layer used in the present invention is preferably a polymer containing a quaternized nitrogen-containing unit as a repeating unit, particularly in the main chain represented by the following formula (1) or (2): A cationic polymer containing a unit having a pyrrolidinium ring as a main repeating unit is preferable in that excellent antistatic performance can be obtained.

In the structure of the above formula (1) or (2), R ¹ and R ² are usually an alkyl group having 1 to 4 carbon atoms or hydrogen, and these may be the same group or different. In addition, the alkyl group of R ¹ and R ² may be substituted with a hydroxyl group, an amide group, an amino group, or an ether group. Further, R ¹ and R ² may be chemically bonded to have a ring structure. The (1) or (2) the X ^- is a halogen ion, a nitrate ion, methanesulfonate ion, ethanesulfonate ion, monomethyl sulfate ion, monoethyl sulfate ion, trifluoroacetate ion, trichloroacetate ion.

Among the above-mentioned cationic polymers containing a unit having a pyrrolidinium ring in the main chain as a main repeating unit, particularly when the structure of formula (1) and X ⁻ is a chlorine ion, the antistatic performance is excellent. In addition, the humidity dependency of the antistatic performance is small, which is preferable in that the decrease in the antistatic performance is reduced even under a low humidity. In applications where halogen ions cannot be used in the coating layer, antistatic performance close to that of chlorine ions can be obtained by using methanesulfonic acid or monomethyl sulfate ions instead of chlorine ions.
The polymer having the unit of the formula (1) as a repeating unit is polymerized by using the diallylammonium salt represented by the following formula (3) as a monomer and ring-closing by radical polymerization in a medium mainly containing water. It is obtained by. The polymer having the unit of the formula (2) as a repeating unit can be obtained by cyclopolymerizing the monomer of the formula (3) in a system using sulfur dioxide as a medium.

  Further, when the polymer having the unit represented by the formula (1) or (2) as a repeating unit is a homopolymer composed of a single unit, better antistatic performance can be obtained.

  The cationic polymer contained in the coating layer is, for example, represented by the formula (4) or (5) in addition to the cationic polymer containing a pyrrolidinium ring as a repeating unit in the main chain represented by the formula (1) or (2). A cationic polymer having a repeating unit as a repeating unit may be used.

In the structure of the above formula (4) or (5), R ³ and R ⁸ are each independently hydrogen or a methyl group, and R ⁴ and R ⁹ are each independently independently usually having 2 carbon atoms. ˜6 alkyl groups. R ⁵ , R ⁶ , R ⁷ , R ¹⁰ , R ¹¹ and R ¹² are a methyl group, a hydroxyethyl group or hydrogen, and these may be the same group or different. Further, X ⁻ in the formula (4) or (5) is a halogen ion, nitrate ion, methanesulfonate ion, ethanesulfonate ion, monomethyl sulfate ion, monoethyl sulfate ion, trifluoroacetate ion, or trichloroacetate ion.

  In the cationic polymer having the unit represented by the formula (4) or the formula (5) as a repeating unit, for example, an acrylic acid monomer or a methacrylic acid monomer corresponding to each unit is radically polymerized in a medium mainly containing water. However, the present invention is not limited to this.

  The average molecular weight (number average molecular weight) of the cationic polymer in the coating layer used in the present invention is usually in the range of 1,000 to 500,000, more preferably 5,000 to 100,000. If the average molecular weight is less than 1000, it may cause the cationic polymer to transfer or block on the overlapping surface when the film is wound, and conversely if the average molecular weight exceeds 500,000, the coating solution containing this It becomes difficult to uniformly apply to the film surface.

  In order to improve adhesiveness with the polyester film used as the substrate in the coating layer used in the present invention, it is preferable to add a binder polymer to the coating layer. Examples of the binder polymer include polyester, polyacrylate, and polyurethane. These polymers can be rendered water-soluble or water-dispersed by copolymerizing a nonionic, cationic, or amphoteric hydrophilic component as one component of the monomer. In addition, nonionic, cationic, or amphoteric surfactants are used to disperse in water by so-called forced emulsification, or emulsion polymerization is performed using nonionic, cationic, or amphoteric surfactants. It can also be made into a dispersion. Furthermore, these polymers can also be used as copolymers, and may be any of random copolymers, block copolymers, and graft copolymers, or may be a conjugate with a different polymer. Examples include, but are not limited to, urethane-graft-polyacrylate or polyester-graft-polyacrylate obtained by emulsion polymerization of an acrylic monomer in the presence of an aqueous solution or dispersion of polyurethane or polyester. Absent.

The surface specific resistance value of the coating layer containing the polymer antistatic agent described above needs to be 1 × 10 ¹³ Ω or less, preferably 1 × 10 ¹¹ Ω or less, more preferably 1 × 10 ¹⁰ Ω. The lower limit is not particularly limited, but is usually 1 × 10 ⁸ Ω. When the surface specific resistance value exceeds 1 × 10 ¹³ Ω, static electricity generated on the film surface cannot be effectively removed even if normal charge removal is performed. For example, when the film is rolled up, The distribution pattern of static electricity (referred to as a charging pattern or a static mark) remaining on the film is likely to be generated, or discharge is likely to occur when the film is unwound from a roll. Furthermore, it is not preferable because fine dust or the like easily adheres to the film surface due to electrification, resulting in a circuit defect.

  The coating layer containing the polymer antistatic agent described above is coated on the polyester film as a coating solution mainly using water as a medium, but the stability of the coating solution is improved, or the coating properties and coating film properties are improved. Therefore, in addition to water, it is possible to add an organic solvent in an amount of usually 10% by weight or less. Examples of the organic solvent include alcohols such as ethanol, isopropanol, ethylene glycol, and glycerin, ethyl cellosolve, t-butyl cellosolve, ethers such as propylene glycol monomethyl ether and tetrahydrofuran, ketones such as acetone and methyl ethyl ketone, Examples thereof include amines such as dimethylethanolamine and trimethanolamine, and amides such as N-methylpyrrolidone. These can be used alone or in combination.

  In the present invention, the above aqueous coating solution is applied to at least one side of a polyester film. This film is a polyester film before crystal orientation is completed, and after application, is further stretched in at least one direction and then heat-set. It is preferred that Specifically, after applying an aqueous coating solution to an unstretched film, when the film is stretched simultaneously or sequentially in the machine direction and the transverse direction, and then heat-set, after applying the film uniaxially stretched in the machine direction or the transverse direction When stretched in a direction perpendicular to the previous stretching and then heat-set, after being applied to a film biaxially stretched in the vertical and horizontal directions, then stretched again in the vertical or horizontal or both directions and then heat-set Can be illustrated. By using such a so-called in-line coating method, the coating layer is usually heat-set at a high temperature of 200 ° C. or higher, so that the adhesion between the coating layer and the polyester film is improved.

  Any known method can be applied as a method of applying the coating solution to the polyester film as the substrate. Specifically, roll coating method, gravure coating method, micro gravure coating method, reverse coating method, bar coating method, roll brush method, spray coating method, air knife coating method, impregnation method, curtain coating method, die coating method, etc. It can be applied alone or in combination.

  The thickness of the coating layer containing the polymer antistatic agent of the biaxially oriented polyester film in the present invention is usually 0.01 to 0.5 μm as a final dry thickness, and further 0.02 to 0.3 μm. Is preferred. When the thickness of the coating layer is less than 0.01 μm, antistatic performance and adhesiveness are insufficient, and when it exceeds 0.5 μm, blocking tends to occur. Moreover, the coating layer containing a polymer antistatic agent may be coated only on one side of the film or on both sides. Furthermore, in the case of coating only on one side of the film, it is possible to simultaneously coat another coating layer different from the coating layer described above.

  The curable resin used for the interlayer insulating layer used in the present invention can be used without particular limitation as long as it can form a layer on a support and has sufficient insulating properties. System, polyimide resin system, polyimide amide resin system, polycyanate resin system, polyester resin system, thermosetting polyphenylene ether resin system, and the like. Further, two or more of these may be used in combination, or a multilayer structure may be used.

  A method for forming an interlayer insulating layer on a support is a known method in which the resin composition varnish in which the above-described thermosetting resin or the like is dissolved in a solvent is applied, and then the solvent is dried by heating to simultaneously cure the resin. Can be created by the method.

  In the present invention, a cured resin layer serving as an interlayer insulating layer is provided as a laminated film on a support made of a polyester film, and the laminated film is formed into a roll shape. When making it into a roll shape, it does not matter whether it can be stored as it is, in a state where a protective film for protecting the surface of the cured resin is bonded, or in a roll state. However, by protecting with a protective film, it is possible to prevent the adhesion and scratches of dust etc. to the surface of the resin composition layer, so even if it is a roll without a protective film, finally the protective film It is preferable to add a step of bonding.

  The protective film is not particularly limited as long as it has a function of protecting the surface of the interlayer insulating layer, and a plastic film such as polyethylene, polypropylene, or polyester is used.

  The thickness of the interlayer insulating layer formed of the polyester film is not less than the thickness of the conductor layer. Since the thickness of the conductor layer of the circuit board is usually in the range of 5 to 70 μm, the thickness of the resin composition layer is preferably 10 to 100 μm.

  The film having an interlayer insulating layer obtained in the present invention is laminated on the core substrate by peeling off the protective film of the interlayer insulating layer as an adhesive film when patterning the conductive layer to form a circuit. Structure of core base material / interlayer insulating layer / polyester film support, or structure of polyester film support / interlayer insulation / core base material / interlayer insulating layer / polyester film support in which both sides of the core base material are sandwiched between interlayer insulating layers The core substrate and the interlayer insulating layer are adhered to each other by heating, and the support made of the polyester film is peeled off.

  As a method of adhering the interlayer insulating layer to the core substrate, a method of laminating on the circuit board under reduced pressure by a vacuum laminating method is suitably used. The laminating method may be a batch method or a continuous method using a roll. Further, the adhesive film and the circuit board may be heated (preheated) as necessary before lamination.

  The lamination conditions are such that the pressure bonding temperature (laminating temperature) is preferably 70 to 140 ° C., the pressure bonding pressure is preferably 1 to 11 kgf / cm 2 (9.8 × 10 4 to 107.9 × 104 N / m 2), and the air pressure is 20 mmHg ( It is preferable to laminate under a reduced pressure of 26.7 hPa) or less. The vacuum lamination can be performed using a commercially available vacuum laminator.

  The circuit board in the present invention mainly includes a conductor layer (circuit) patterned on one or both sides of a substrate such as a glass epoxy, metal substrate, polyester substrate, polyimide substrate, BT resin substrate, thermosetting polyphenylene ether substrate, or the like. The one formed. Also included in the circuit board of the present invention is a multilayer printed wiring board in which conductor layers and insulating layers are alternately formed and a conductor layer (circuit) is patterned on one or both sides. In addition, it is preferable from the viewpoint of the adhesiveness of the insulating layer to the circuit board that the surface of the conductor circuit layer has been previously roughened by blackening or the like.

  Thus, after laminating the adhesive film on the circuit board, when the support film is peeled off, the insulating film can be formed on the circuit board by peeling and thermosetting. The conditions of heat curing are selected in the range of 20 to 180 minutes at 150 to 220 ° C, more preferably 30 to 120 minutes at 160 to 200 ° C.

  If the support film is not peeled off after the insulating layer is formed, it is peeled off here. Next, holes are formed in the insulating layer formed on the circuit board to form via holes and through holes. Drilling can be performed by a known method such as drilling, laser, or plasma, or a combination of these methods if necessary. However, drilling by a laser such as a carbon dioxide laser or YAG laser is the most common method. .

  Next, although the manufacture example of the polyester film in this invention is demonstrated concretely, it is not limited to the following manufacture examples at all.

  First, a method of using the polyester raw material described above and cooling and solidifying a molten sheet extruded from a die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and an electrostatic application adhesion method and / or a liquid application adhesion method are preferably employed. Next, the obtained unstretched sheet is stretched in the biaxial direction. In that case, first, the unstretched sheet is stretched in one direction by a roll or a tenter type stretching machine. The stretching temperature is usually 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, the extending | stretching temperature orthogonal to the 1st step | paragraph extending | stretching direction is 70-170 degreeC normally, and a draw ratio is 3.0-7 times normally, Preferably it is 3.5-6 times. Subsequently, heat treatment is performed at a temperature of 180 to 270 ° C. under tension or under relaxation within 30% to obtain a biaxially oriented film. In the above-described stretching, a method in which stretching in one direction is performed in two or more stages can be employed. In that case, it is preferable to carry out so that the draw ratios in the two directions finally fall within the above ranges.

  The simultaneous biaxial stretching method can also be adopted for the production of the polyester film in the present invention. The simultaneous biaxial stretching method is a method in which the unstretched sheet is usually stretched and oriented in the machine direction and the width direction at 70 to 120 ° C., preferably 80 to 110 ° C., and the stretching ratio is as follows: The area magnification is 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times. Subsequently, heat treatment is performed at a temperature of 170 to 250 ° C. under tension or under relaxation within 30% to obtain a stretched oriented film. With respect to the simultaneous biaxial stretching apparatus that employs the above-described stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be employed.

  Furthermore, a so-called coating stretching method (in-line coating) in which the film surface is treated during the above-described polyester film stretching step can be applied. When a coating layer is provided on a polyester film by a coating stretching method, coating can be performed simultaneously with stretching and the thickness of the coating layer can be reduced according to the stretching ratio, producing a film suitable as a polyester film. it can.

  In the present invention, as a method for providing the coating layer, a conventionally known coating method such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating, curtain coating or the like can be used. Regarding the coating method, there is a description example in “Coating method” published by Yasuharu Harasaki in 1979.

  In this invention, it does not necessarily limit about the curing conditions at the time of forming a coating layer on a polyester film, For example, when providing a coating layer by the coating extending | stretching method (in-line coating), it is 170-280 degreeC normally. The heat treatment may be performed for 3 to 40 seconds, preferably 200 to 280 ° C. for 3 to 40 seconds.

  Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed irrespective of the coating extending | stretching method (in-line coating) or offline coating.

  The polyester film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The measuring method used in the present invention is as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Measurement of average particle diameter (d ₅₀ : μm) Integration (weight basis) 50% in equivalent spherical distribution measured using centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type manufactured by Shimadzu Corporation) Was the average particle size.

(3) Surface roughness (SRa)
The center line average roughness Ra (μm) is defined as the surface roughness. It calculated | required as follows using the Kosaka Laboratory Co., Ltd. surface roughness measuring machine (SE-3F). That is, a portion having a reference length L (2.5 mm) is extracted from the film cross-section curve in the direction of the center line, the center line of the extracted portion is the x axis, and the direction of the vertical magnification is the y axis. When represented by (x), the value given by the following equation is represented by [μm]. The center line average roughness was represented by the average value of the center line average roughness of the extracted portion obtained from 10 cross section curves obtained from the sample film surface. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.
Ra = 1 / L∫ ₀ ^L | f (x) | dx

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyester A)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, after adding 0.04 part of ethylene glycol slurry ethyl acid phosphate and 0.03 part of antimony trioxide, the temperature reached 280 ° C. and the pressure reached 15 mmHg in 100 minutes. It was 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyethylene terephthalate having an intrinsic viscosity of 0.65.

Production Example 2 (Polyester B)
Agglomerates having an average particle diameter of 150 nm were obtained by dispersing the aggregates of θ-type aluminum oxide having a primary particle diameter of 30 nm in ethylene glycol obtained by heating and baking boehmite, and gradually dispersing them with a sand grinder. . Next, 100 parts of dimethyl terephthalate, 65 parts of ethylene glycol and 0.09 part of magnesium acetate were placed in a reactor, and the ester exchange reaction was performed while heating and raising the temperature and distilling off methanol. Approximately 4 hours after the start of the reaction, the temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 3.0% by weight of an aluminum oxide aggregate having an average particle size of 70 nm was added, and 0.4 parts of ethylene glycol slurry ethyl phosphate and 0.03 part of antimony trioxide were added, followed by polymerization according to a conventional method. A polyethylene terephthalate having an intrinsic viscosity of 0.63 was obtained.

Production Example 3 (Polyester C)
100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, the temperature is raised by heating, methanol is distilled off, transesterification is performed, and 4 hours are required from the start of the reaction. The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 part of ethylene glycol slurry ethyl acid phosphate, 0.03 part of antimony trioxide and 0.2 part of crosslinked polymer particles having an average particle diameter of 0.4 μm were added, and then the temperature was 280 ° C. in 100 minutes. The pressure was allowed to reach 15 mmHg, and thereafter the pressure was gradually reduced to finally 0.3 mmHg. After 4 hours, the system was returned to normal pressure to obtain polyethylene terephthalate having an intrinsic viscosity of 0.61.

Production Example 4 (Polyester D)
In the same manner as in Production Example 3, except that 0.2 parts of synthetic calcium carbonate particles having an average particle diameter of 0.6 μm are added instead of adding 0.2 parts of crosslinked polymer particles having an average particle diameter of 0.4 μm in Production Example 3. Thus, polyethylene terephthalate was obtained.

Production Example 5 (Polyester E)
In the same manner as in Production Example 3, except that 0.5 part of aggregated silica particles having an average particle diameter of 3.2 μm is added instead of adding 0.2 part of crosslinked polymer particles having an average particle diameter of 0.4 μm in Production Example 3. Polyethylene terephthalate was obtained.

Production Example 6 (Polyester F)
In the same manner as in Production Example 3, except that 0.2 part of monodispersed spherical silica particles having an average particle diameter of 0.40 μm is added instead of adding 0.2 part of crosslinked polymer particles having an average particle diameter of 0.4 μm in Production Example 3. Thus, polyethylene terephthalate was obtained.

Production Example 7 (Polyester G)
Similar to Production Example 3 except that 0.2 part of monodispersed spherical silica particles having an average particle diameter of 0.60 μm is added instead of adding 0.2 part of crosslinked polymer particles having an average particle diameter of 0.4 μm in Production Example 3. Thus, polyethylene terephthalate was obtained.

Examples of compounds constituting the coating layer are as follows.
(Example compounds)
-Polymer antistatic agent: (a1)
Quaternary ammonium salt-containing cationic polymer using diallyldimethylammonium chloride (Pyrrolidinium ring-containing cationic polymer of (Formula 1)) Average molecular weight of about 30,000
-Polymer antistatic agent: (a2)
Quaternary ammonium salt-containing cationic polymer using diallylmonomethylammonium methanesulfonate (Pyrrolidinium ring-containing cationic polymer of (Formula 1)) Average molecular weight of about 30,000
-Polymer antistatic agent: (a3)
Poly (trimethylammonium ethyl methacrylate) monomethyl sulfate homopolymer (cationic polymer of formula (5))
-Binder polymer: (b)
Water-based acrylic resin (Nicarbazole with an acid value of 6 mgKOH / g, manufactured by Nippon Carbide Industries Co., Ltd.)
・ Crosslinking agent: (c)
Crosslinkable resin of alkylol melamine / urea copolymer (Bekkamin manufactured by Dainippon Ink and Chemicals)
・ Fine particles: (d)
Ethylene glycol grafted silicon dioxide fine particles (average particle size 0.15 μm, graft rate 1.7 mmol / g)
・ Additive: (e)
Polyethylene oxide adduct to diglycerin skeleton (average molecular weight 450)

(Coating liquid H)
It was set as the aqueous coating liquid which contains the said compound in the ratio of a1 / b / c / d / e = 27/45/20/3/5 (weight%) by the weight composition ratio of solid content conversion.
(Coating liquid J)
It was set as the aqueous coating liquid which contains the said compound in the ratio of a2 / b / c / d / e = 27/45/20/3/5 (weight%) in the weight composition ratio of solid content conversion.
(Coating liquid K)
It was set as the aqueous coating liquid which contains the said compound in the ratio of a3 / b / c / d = 32/45/20/3/3 (weight%) by the weight composition ratio of solid content conversion.
(Coating liquid L)
It was set as the aqueous coating liquid which contains the said compound in the ratio of a3 / b / c / d = 5/72/20/3 (weight%) by weight composition ratio of solid content conversion.

(Manufacture of polyester film)
The above polyesters A to G were mixed into the raw materials of layer A, layer B, and layer C in the mixing ratio shown in Table 1, and each was supplied to three twin-screw extruders and melted at 285 ° C., respectively. A non-oriented sheet was obtained by co-extrusion on a casting drum cooled to 20 ° C. with a constitution of layers (A layer / B layer / C layer) and solidifying by cooling. Next, the film was stretched 3.1 times in the machine direction at 100 ° C.
In Examples 1 to 6 and Comparative Examples 2 to 4, a corona discharge treatment was applied to the surface of the C layer side of the film after longitudinal stretching, and the coating liquid shown in Table 1 was applied. After this, after a preheating step in a tenter, the film was stretched 4.3 times at 120 ° C., heat treated at 225 ° C., and then relaxed by 10% in the width direction at 180 ° C. A polyester film having a thickness shown in Table 1 having a coating layer of 0.08 μm was obtained. Table 1 shows the surface properties of the polyester film obtained by the above method.

  Comparative Example 1 is a mixed raw material of Layer A, Layer B, and Layer C shown in Table 1, and each is supplied to three twin-screw extruders and melted at 285 ° C. (A layer / B layer / C layer) was coextruded on a casting drum cooled to 20 ° C. and cooled and solidified to obtain a non-oriented sheet. Next, the film was stretched 3.1 times in the longitudinal direction at 100 ° C., subjected to a preheating step in the tenter and 4.3 times transverse stretched at 120 ° C., then heat-treated at 225 ° C., and then at 180 ° C. in width. 10% relaxation was added in the direction to obtain a polyester film having the thickness shown in Table 1.

Table 2 below shows the appearance of the polyester film wound up in a roll.
<Roll appearance>
In the production of the polyester film, the state of convex protrusions and wrinkles on the product roll surface of the film was visually observed and evaluated, and the results are shown in Table 2.
(Roll appearance is good) ◎>○>△> × (Roll appearance is bad)
Among the above criteria, those above Δ are levels that can be used without any problem in actual use.

  In Comparative Example 3, the ratio of the product roll in which convex protrusions were generated in the roll shape of the polyester film was high, and application defects of the resin composition varnish occurred at the protrusions, and the product could not be obtained. Table 2 shows the results of the surface observation of the interlayer insulating layer in the portions having no coating defects.

  In Comparative Example 4, when the polyester film was rolled up, the ratio of the product roll in which wrinkles were generated was high, and the resin composition varnish could not be uniformly applied at the wrinkled part. Table 2 shows the results of surface observation of the interlayer insulating layer at portions other than wrinkles.

《Dustproof property》
The film rolled up as a product roll was unwound, and the deposits on the film surface that could be seen per 1 m ² were counted by visual inspection.
○: There was no deposit.
Δ: Adhered matter is 10 pieces / m ² or less ×: Adhered matter is more than 10 pieces / m ² Among the above judgment criteria, those of Δ or more are levels that can be used without problems in actual use.
<Charging>
Table 2 shows the results of the observation of the charge trace on the surface of the product roll and the observation of the state of the film unwound from the product roll, and the evaluation by the following rank.
◯: No fuzzing or film sticking Δ: Slightly fuzzing is felt on the film surface drawn from the roll ×: There is a charge mark on the roll surface. Alternatively, when the unrolled film is released, the roll surface sticks. Among the above criteria, those above Δ are levels that can be used without any problem in actual use.

<< Epoxy resin composition >>
20 parts of liquid bisphenol A type epoxy resin (“Epicoat 828EL” manufactured by Japan Epoxy Resin Co., Ltd.), 20 parts of brominated bisphenol A type epoxy resin (YDB-500 manufactured by Toto Kasei Co., Ltd.), cresol novolac type epoxy resin (epoxy) Equivalent 215, softening point 78 ° C., Dainippon Ink Chemical Co., Ltd. Epiklone N-673) 20 parts, terminal epoxidized polybutadiene rubber (Nagase Kasei Kogyo Co., Ltd. Denarex R-45EPT) 15 parts are stirred in MEK. The solution was dissolved while heating, and brominated phenoxy resin varnish (non-volatile content 40% by weight, bromine content 25% by weight, solvent composition, xylene: methoxypropanol: methyl ethyl ketone = 5: 2: 8, YPB- manufactured by Toto Kasei Co., Ltd. 40-PXM40) 50 parts, 2,4-diamino as epoxy curing agent 6- (2-Methyl-1-imidazoliethyl) -1,3,5-triazine / isocyanuric acid adduct 4 parts, 2 parts of finely pulverized silica, 4 parts of antimony trioxide and 5 parts of calcium carbonate A composition varnish was prepared.

<< Resin composition varnish application to polyester film: Formation of interlayer insulation layer >>
The resin composition varnish produced by the above method is applied to the surface of the B layer of the polyester film obtained in Examples 1 to 6 and Comparative Examples 1 to 4 with a die coater so that the resin thickness after drying becomes 70 μm. It apply | coated and dried at 80-120 degreeC (average 100 degreeC), and the interlayer insulation layer which made the polyester film the support body was produced.

<Surface property of interlayer insulating layer>
The surface corresponding to the polyester film of the obtained interlayer insulation layer was observed with SEM, and the presence or absence of a dent affecting the wiring was evaluated as follows. The results are shown in Table 2.
◎: No large dents that adversely affect the wiring ○: Slightly inferior dents and some large dents △: There is a level of dents that can be used practically without problems ×: There are large dents There are dents that adversely affect circuit wiring. Among the above criteria, those above Δ are levels that can be used without problems in actual use.

《Cost advantage》
The obtained characteristics and the cost evaluation related to production such as yield are evaluated as follows, and the results are shown in Table 2.
◯: Advantage in terms of cost Δ: Slightly inferior in cost ×: Inferior in cost Among the above criteria, those above Δ are at a level that can be used without problems in actual use.

  The polyester film of the present invention can be suitably used as a support for forming a film-like interlayer insulating material used for a multilayer printed wiring board produced by a build-up build-up method.

Claims (1)

Interlayer insulating material-supported polyester having a coating layer on one side of a biaxially oriented laminated polyester film comprising at least three layers obtained by coextrusion method, and simultaneously satisfying the following formulas (1) to (4) the film.
SRaA ≦ 15 (1)
15 ≦ dT (2)
cB ≦ 100 (3)
R ≦ 1.0 × 10 ¹³ (4)
(In the above formula, SRaA is the center line average roughness (nm) of the surface opposite to the surface having the coating layer, dT is the thickness of the film (μm), cB is the average particle diameter contained in the intermediate layer 0.4 μm) (The above particle amount (ppm), R represents the surface specific resistivity (Ω / □) of the coating layer surface)