JP2012051367A - Polyester film for supporting interlayer insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film that can cope with various problems that occur in miniaturization and densification of wiring and is suitable as a support film for an interlayer insulating material.
SOLUTION: A coating layer is provided on the other surface of a polyester film having a center line average roughness (SRa) of 0.5 to 15 nm on one film surface, and the coating is performed after heat treatment at 180 ° C. for 30 minutes. An interlayer insulating material-supporting polyester film, wherein the oligomer amount on the surface of the layer is 3.0 mg / m ² or less.
[Selection figure] None

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. Using a laminator, it is peeled off after being bonded onto the circuit board.

  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.

  Print out by repeating the process of forming a wiring pattern on a rigid board, forming an insulating layer on it, forming a wiring pattern on it, and then forming an insulating layer. The build-up method for forming wiring boards is used as a method suitable for products that require miniaturization, such as mobile phones, and for applications that require high-speed operation, such as computers. As the performance increases, the build-up layer is further multi-layered, and the miniaturization and density of 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, with regard to the film that is a support for forming a film-like insulating layer, specific proposals are made despite the great influence on the surface properties of the insulating layer and the productivity when forming the insulating layer. The situation has not been made. In particular, the miniaturization and high density of wiring have progressed, and the adverse effects on the electrical characteristics due to the minute surface defects and impurities on the surface of the interlayer insulating layer have become apparent. No proposal has been made regarding the film used for the support.

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

  The present invention has been made in view of the above circumstances, and the problem to be solved can cope with various problems that occur in miniaturization and densification of wiring, and support for interlayer insulating materials. It is providing the polyester film suitable as a film.

  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 the other surface of a polyester film having a center line average roughness (SRa) of one film surface of 0.5 to 15 nm and heat-treated at 180 ° C. for 30 minutes. It exists in the interlayer insulation material support polyester film characterized by the oligomer amount of the said coating layer surface of the back being 3.0 mg / m < ² > or less.

  ADVANTAGE OF THE INVENTION According to this invention, the polyester film suitable as a support film for interlayer insulation materials which can respond to the various problems generate | occur | produced in refinement | miniaturization and high density of wiring can be provided, and the industrial film of this invention Value is high.

In the polyester film of the present invention, the amount of the polyester oligomer on the surface of the coating layer after heat-treating the film at 180 ° C. for 30 minutes needs to be 3.0 mg / m ² or less. If the amount of polyester oligomer on the surface of the coating layer after heat treatment exceeds this range, the oligomer deposited from the film fouls the processing equipment due to heat treatment in the process of forming the interlayer insulating layer on the substrate, resulting in defects during lamination, Productivity decreases. Further, the precipitated and accumulated oligomers are mixed into the wiring board, so that the electrical characteristics are impaired, or electrical defects are generated.

The surface resistivity of the coated layer surface of the polyester film of the present invention is preferably 1 × 10 ¹³ Ω / □ or less, more preferably 1 × 10 ¹² Ω / □ or less, particularly preferably. 1 × 10 ¹⁰ Ω / □ or less. When the surface resistivity exceeds 1 × 10 ¹³ Ω / □, when the film wound in a roll shape is unwound or when the laminated single film is sequentially conveyed, It may cause problems such as processing defects and adhesion of foreign matter and dust.

  In the present invention, as a component constituting the coating layer provided on the film, a compound having a quaternary ammonium base or polyvinyl alcohol is preferably used. The compound having a quaternary ammonium base refers to a compound having a component containing a quaternary ammonium base in the main chain or side chain in the molecule. Examples of such constituents include pyrrolidinium ring, quaternized alkylamine, copolymerized with acrylic acid or methacrylic acid, quaternized N-alkylaminoacrylamide, vinylbenzyltrimethylammonium salt, 2 -Hydroxy 3-methacryloxypropyltrimethylammonium salt etc. can be mentioned. Further, these may be combined or copolymerized with other resins. In addition, examples of anions that serve as counter ions for these quaternary ammonium salts include ions such as halogen, alkyl sulfate, alkyl sulfonate, and nitric acid.

  In the present invention, the compound having a quaternary ammonium base is preferably a polymer compound. If the molecular weight is too low, it may be easily removed from the coating layer, causing deterioration in performance over time, or the coating layer becoming sticky. Moreover, when the molecular weight is low, the heat resistance stability may be inferior. In order not to cause such a problem, it is desirable that the number average molecular weight of the compound having a quaternary ammonium base is usually 1000 or more, more preferably 2000 or more, particularly 5000 or more. On the other hand, when such a compound has a molecular weight that is too high, problems such as excessively high viscosity of the coating solution may occur. In order not to cause such a problem, the number average molecular weight is preferably 500,000 or less.

  The polyvinyl alcohol used in the present invention can be synthesized by a normal polymerization reaction and is preferably water-soluble. The degree of polymerization of polyvinyl alcohol is not particularly limited, but is usually 100 or more, preferably 300 to 40,000. When the degree of polymerization is 100 or less, the water resistance of the coating layer tends to decrease. The degree of saponification of polyvinyl alcohol is not particularly limited, but a polyvinyl acetate saponified product that is usually 70 mol% or more, preferably 80 mol% or more and 99.9 mol% or less is practically used. Furthermore, in the coating layer, one or more of water-soluble or water-dispersible binder resins other than those described above can be used in combination as required. Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and the like. In these, each skeleton structure may have a composite structure substantially by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane.

  Furthermore, if necessary, the coating layer may contain a crosslinking reactive compound. The cross-linking reactive compound mainly improves the cohesiveness, surface hardness, scratch resistance, solvent resistance, and water resistance of the coating layer by a cross-linking reaction with the functional group contained in the coating layer component. preferable. The coating layer of the film of the present invention comprises a surfactant, an antifoaming agent, a coating property improving agent, a thickener, an antistatic agent, an organic lubricant, organic particles, inorganic particles, an antioxidant, an ultraviolet absorber, and foaming. Additives such as agents, dyes, and pigments may be contained. These additives may be used alone or in combination of two or more as necessary.

  The ratio of the compound having a quaternary ammonium base in the coating layer constituting component is usually 10 to 99% by weight, preferably 20 to 95% by weight. If the ratio is too high or too low, the desired antistatic performance and oligomer precipitation prevention performance may not be obtained. The coating liquid used in the present invention is preferably an aqueous solution or an aqueous dispersion in terms of handling and working environment, but contains water as the main medium and contains an organic solvent as long as it does not exceed the gist of the present invention. You may do it. Although there is no restriction | limiting in particular in the solid content density | concentration of a coating liquid, Usually, 0.3 to 65 weight%, Preferably it is 0.5 to 30 weight%, More preferably, it is 1 to 20 weight%. When the concentration is too high or too low than these ranges, it may be difficult to provide a coating layer having a thickness necessary for fully expressing the function.

The thickness of the coating layer is a dry thickness, and is usually 0.003 to 1.5 μm, preferably 0.005 to 0.5 μm, and more preferably 0.01 to 0.3 μm. If the thickness of the coating layer is less than 0.003 μm, sufficient performance may not be obtained, and if it exceeds 1.5 μm, blocking between films tends to occur. As a method of providing the coating layer on the polyester film, a method of applying the coating solution in the process of producing the polyester film is suitably employed. For example, there are a method of stretching after applying to an unstretched film, a method of stretching after coating to a uniaxially stretched film, a method of stretching after coating to a biaxially stretched film, and the like. In particular, it is economical to apply a coating solution to an unstretched or uniaxially stretched film and then perform drying and stretching simultaneously in a tenter.

  As a method for applying the coating solution to the polyester film, for example, a coating technique as shown in “Coating system” published by Yuji Harasaki, Tsuji Shoten, published in 1979 can be used. Specifically, air doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, cast coater, spray coater, curtain coater, calendar coater And techniques such as an extrusion coater and a bar coater.

  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.

  In the polyester film of the present invention, the B layer is adjacent to the outermost layer A layer constituting the surface opposite to the surface having the coating layer described above, and the outermost layer opposite to the A layer is used for each surface layer. The raw material which mix | blended the same particle | grain or different particle | grains can be used for polyester.

  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 the present invention, the A layer 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, particles having an average particle diameter of usually 0.1 to 0.6 μm, preferably 0.2 to 0.5 μm are contained. If the average particle size is less than 0.1 μm, the surface roughness of the film is low, the film slipperiness is poor, and the film surface may be easily damaged. You may not be able to get the product. 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 layer A of the polyester film is usually 100 to 2000 ppm, preferably 200 to 1500 ppm, and more preferably 500 to 1000 ppm. If the content of the particles is less than 100 ppm, the slipperiness of the film tends to be poor, and if the content exceeds 2000 ppm, the surface roughness of the film becomes too large and the flatness may 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 a particle size of 0.4 μm or more in the B layer of the polyester film is usually 100 ppm or less, preferably 50 ppm or less, more preferably 0 ppm. If it exceeds 100 ppm, waviness occurs on the surface of the A layer of the polyester film, which may cause adverse effects on the finer wiring and higher circuit density.

One of the characteristics of the present invention is that the polyester film serving as the support has a specific surface, and at least the center line average roughness SRaA on one side of the polyester film is 0.5 nm to 15 nm, preferably 0.5 nm. The range is from -10 nm. When the center line average roughness SRaA is less than 0.5 nm, the slipperiness of the film and the air leakage between the films are poor, the film surface is likely to be damaged, and a product cannot be obtained in a roll state after film formation.
In addition, when the center line average roughness SRaA exceeds 15 nm, it is not preferable because adverse effects are caused in the miniaturization of wiring and the increase in density of circuits.

  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 center line average roughness Ra of the coating layer surface of the polyester film on which the thermosetting resin is applied and the interlayer insulating layer is formed is usually 30 nm or less, preferably 20 nm or less, and the ten-point average roughness Rz is usually 200 nm. Hereinafter, it is preferably 100 nm or less. When the centrality average roughness Ra of the coating layer surface exceeds 30 nm or the ten-point average roughness Rz exceeds 200 nm, the surface roughness of the interlayer insulating layer increases, which has an adverse effect on circuit density. May occur.

  The thickness of the polyester film of the present invention is not particularly limited as long as it can be formed as a film, but is usually 15 to 50 μm, preferably 20 to 40 μm. If the film thickness is less than 15 μm, wrinkles tend to occur when an insulating material is applied, and if the film thickness exceeds 50 μm, the amount of polyester used increases, resulting in an increase in cost.

  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. 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 a polyester film is usually 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 laminating conditions are preferably a pressure bonding temperature (laminating temperature) of 70 to 140 ° C. and a pressure bonding pressure of preferably 1 to 11 kgf / cm ² (9.8 × 10 ^{4 to} 107.9 × 10 ⁴ N / m ² ). Lamination is preferably performed under a reduced pressure of 20 mmHg (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

(4) Surface resistivity value Using a high resistance measuring instrument (HP4339B) and measuring electrode (HP16008B) manufactured by Hewlett-Packard Japan, fully controlled the sample in a measurement atmosphere of 23 ° C. and 50% RH, and then applied voltage 100V The surface specific resistance value of the coating layer after 1 minute was measured.

(5) Heat treatment method of film A4 size Kent paper and a heat-treated polyester film are overlapped. At that time, clip the four corners with a zem clip or the like so that the surface on which the amount of oligomer is measured is on the outside, and stop the Kent paper and the polyester film. The polyester film is left to stand for 30 minutes in an oven at 180 ° C. in a nitrogen atmosphere, and heat treatment is performed.

(6) Method for measuring film surface oligomer amount The film is heat-treated at 180 ° C. for 30 minutes by the method shown in (5) above. Next, the polyester film is folded so that the upper part is opened and the area of the bottom side is 250 cm 2 to create a square box. When the coating layer is provided, the coating layer surface is set to the inside. Next, 10 ml of DMF (dimethylformamide) is placed in the box prepared by the above method, and the DMF is recovered after being left for 3 minutes. The recovered DMF is supplied to liquid chromatography (Shimadzu LC-7A) to determine the amount of polyester oligomer in DMF, and the value of this oligomer amount is divided by the area of the film contacted with DMF to determine the amount of oligomer on the film surface ( mg / m2).

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.

The coating solutions used in the following examples and comparative examples are as follows.
(Coating liquid H)
A polymer having a pyrrolidinium ring in the main chain, a solol produced by Daiichi Kogyo Seiyaku Co., Ltd./silica sol having a degree of saponification = 88 mol%, a degree of polymerization = 500, a polyvinyl alcohol / average particle size of 0.06 μm, Aqueous coating solution containing 85/13/2 by weight composition ratio

(Coating liquid J)
Daikoku Ink Chemical Co., Ltd. Becamine / Daikyoku Kagaku Kogyo Co., Ltd., which is a polymer having a pyrrolidinium ring in the main chain, made of Sharol DC-303P manufactured by Daiichi Kogyo Seiyaku Co., Ltd. An aqueous coating solution containing silica sol having an average particle size of 0.06 μm in a weight composition ratio of 40/22/35/3 in terms of solid content

(Coating liquid K)
Polytrimethylaminoethyl methacrylate quaternized product / 10 saponification degree = 88 mol%, polymerization degree = 500 polyvinyl alcohol / methoxymethylol melamine, Dai Nippon Ink Chemical Co., Ltd. becamine / silica sol having an average particle size of 0.06 μm Aqueous coating solution containing 40/22/35/3 by weight composition ratio in terms of minutes

(Coating liquid L)
By a conventional method, a compound (a1) obtained by copolymerizing trimethylaminoethyl methacrylate quaternized product / methyl methacrylate in a weight composition ratio of 65/35 was obtained. Using this compound a1, a silica sol having a becamine / average particle size of 0.06 μm manufactured by Dainippon Ink & Chemicals, which is a polyvinyl alcohol / methoxymethylol melamine having a1 / saponification degree = 88 mol% and a polymerization degree = 500, Aqueous coating solution containing 70/12/15/3 in terms of weight composition ratio in terms of weight

(Coating liquid M)
A silica sol having a becamine / average particle size of 0.06 μm manufactured by Dainippon Ink & Chemicals, Inc., having a degree of saponification = 88 mol% and a degree of polymerization = 500, is 85/12. / 3 aqueous coating solution

(Coating liquid N)
Dainippon Ink Chemical Co., Ltd. is a nitrazole / methoxymethylol melamine manufactured by Nippon Carbide Industries Co., Ltd., an acrylic resin having a Tg of about 40 ° C., which is a copolymer of polytrimethylaminoethyl methacrylate quaternary product / alkyl acrylate and alkyl methacrylate. Aqueous coating solution containing industrial becamine / silica sol with an average particle size of 0.06 μm in a weight composition ratio of 40/22/35/3 in terms of solid content

(Manufacture of polyester film)
The above polyesters A to G are mixed raw materials of the A layer, the B layer, and the C layer at the blending ratio shown in Table 1 below, and each is supplied to three twin-screw extruders and melted at 285 ° C. A non-oriented sheet was obtained by co-extrusion on a casting drum cooled to 20 ° C. in a three-layer structure (A layer / B layer / C layer) and cooled and solidified. 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, corona discharge treatment was applied to the C layer side surface of the film after longitudinal stretching, and the coating liquid shown in Table 1 was applied to the C layer surface. 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 summarizes the surface characteristics of the obtained polyester film.

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 a polyester film, convex projections and wrinkles were visually evaluated on the surface of a product roll obtained by slitting the film to a length of 10,000 m with a width of 1500 mm. The rank was divided according to the ratio of protrusions and wrinkles per 100 rolls, and the results are shown in Table 2.
○: Roll appearance defect is less than 5%. Δ: Roll appearance defect is 5% or more and less than 10%. X: Roll appearance defect is 10% or more. Is a level.

  In Comparative Examples 1 and 3, the ratio of product rolls in which convex protrusions were generated in the form of polyester film rolls was high, and application defects of the resin composition varnish occurred at the protrusions, and no product was obtained. Table 2 shows the results of the surface observation of the interlayer insulating layer in the portion having no coating defect.

《Dustproof property》
Table 2 shows the results of counting the number of deposits on the surface of the support film that were visible per 1 m ² by visual inspection on the surface side of the support film in the configuration of substrate / interlayer insulating layer / support film, and evaluating with the following rank.
○: No deposits Δ: No more than 10 deposits / m ² ×: More than 10 deposits / m ^{2 Of the} above judgment criteria, those above Δ are those 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: Slight fuzzing is felt on the surface of the film drawn out from the roll ×: The surface of the roll is charged, or the roll surface sticks when the unrolled film is released. The above is a level that can be used without problems 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 while stirring in MEK Heat-dissolved, brominated phenoxy resin varnish (non-volatile content 40 wt%, bromine content 25 wt%, solvent composition, xylene: methoxypropanol: methyl ethyl ketone = 5: 2: 8, YPB-40 manufactured by Toto Kasei Co., Ltd. -PXM40) 50 parts, 2,4-diamino- as epoxy curing agent Resin composition by adding 4 parts of-(2-methyl-1-imidazoliethyl) -1,3,5-triazine isocyanuric acid adduct, 2 parts of finely pulverized silica, 4 parts of antimony trioxide and 5 parts of calcium carbonate A varnish was prepared.

<< Resin composition varnish application to polyester film: Formation of interlayer insulation layer >>
The resin composition varnish produced by the above method was applied on the layer A 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 was 70 μm. And it dried at 80-120 degreeC (average 100 degreeC), and produced the interlayer insulation layer which used the polyester film as the support body.

《Processing machine adhesion》
The lamination surface was set to 130 ° C., and the press bonding was repeated 100 times, and then the press surface was visually evaluated. The results are shown in Table 2.

(Press surface appearance is good) ○>△> × (Stain is seen on the press surface and poor appearance)
Among the above criteria, those above Δ are levels that can be used without any problem in actual use.

<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.
○: There is no dent on the appearance, or a slight dent is seen. △: The size of the dent that can be used practically without problems is seen. ×: There is a big dent, and there is a dent that adversely affects circuit wiring. Among the determination criteria, those above Δ are levels that can be used without any problem 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.
◯: Superior in cost △: Slightly inferior ×: Inferior in cost Among the above criteria, those above Δ are at a level where they 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 (4)

Oligomer on the surface of the coating layer after having a coating layer on the other side of the polyester film having a center line average roughness (SRa) of 0.5 to 15 nm and heat-treating at 180 ° C. for 30 minutes An interlayer insulating material-supporting polyester film, characterized in that the amount is 3.0 mg / m ² or less. A biaxially oriented laminated polyester film comprising at least three layers obtained by coextrusion method, one surface layer having a thickness of 0.4 to 5 μm, and an average particle size of 0.4 μm in a layer adjacent to the surface layer 2. The interlayer insulating material-supported polyester film according to claim 1, wherein the amount of the particles is 100 ppm or less and the thickness of the layer is 1.0 μm or less. The interlayer insulating material-supporting polyester film according to claim 1 or 2, wherein the coating layer contains a compound having a quaternary ammonium base. The interlayer insulating material-supporting polyester film according to any one of claims 1 to 3, wherein the coating layer surface has a surface resistivity of 1 x 10 ¹³ Ω / □ or less.