JP5907640B2 - Release film - Google Patents

Description

  The present invention is, for example, a support for forming a film-like insulating layer, a so-called interlayer insulating layer, which can be suitably used for a build-up type multilayer printed wiring board in which conductor circuit layers and insulating layers are alternately stacked. The present invention relates to a release film having good release properties, transferability, blocking properties, and surface smoothness.

  Conventionally, printed wiring boards have been used in home appliances such as liquid crystal televisions, computers and measuring instruments. Printed wiring board base materials are mainly manufactured from paper-based phenolic resin laminates for consumer use, and glass cloth base laminates using epoxy resin are used for industrial printing. Used as a 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 a wiring board is suitable for use in products that require downsizing, such as mobile phones, and applications that require high-speed operation, such as computers.

  In recent years, with further downsizing and higher performance of electronic devices, the build-up layer tends to be further multilayered, and the miniaturization and higher density of wiring are further progressing.

  Insulating layers used for multilayer printed wiring boards are mainly made of glass cloth impregnated with epoxy or polyimide resin, or ceramic materials. Since it is an important parameter that affects the electrical characteristics such as the characteristic impedance of the plate, it is necessary to select a material that does not impair the desired electrical characteristics.

  The form of the insulating layer is an insulating layer on a film-like support (for example, a release film in which a release layer is provided on a polyester film) as an interlayer insulating material to cope with downsizing and high performance. There has been proposed a method of applying a thermosetting resin or the like to form a roll in which a support film and a cured insulating layer are laminated. For the insulation layer in the film state, the build-up insulation layer is designed so that the resin surface after roughening treatment improves plating adhesion by adapting to laser processing by optimal selection of insulating resin and filler. Many proposals have been made for films having the same.

  However, regarding a release film based on a polyester film used for forming a film-like insulating layer, the surface properties of the insulating layer and the peelability of the insulating layer are greatly affected. Despite the proposal, it was difficult to reach until the desired level of demand was satisfied. In particular, the surface roughness of the interlayer insulating layer to achieve finer and higher density wiring is an important characteristic when formed by coating the insulating layer, but there is a proposal for lowering the roughness of the support. However, it is difficult to cope with the high functionality that will be required in the future.

  Further, in the release film, when the transfer component derived from the release layer is transferred to the other side, the surface of the interlayer insulating layer, there may be a problem that the inherent adhesiveness of the interlayer insulating layer is lowered.

JP-A-7-75274 JP-A-7-264787 JP 2004-265697 A

  The present invention has been made in view of the circumstances as described above, and the problem to be solved is for a multilayer printed wiring board manufactured by a build-up method in order to cope with miniaturization and high density of wiring. An object of the present invention is to provide a release film having good release properties, migration properties, blocking properties, and surface smoothness as a support for forming a film-like interlayer insulating material.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above problem can be easily solved by a release film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is a film having a release layer containing a curable silicone resin on one side of a laminated polyester film composed of at least two layers, the polyester layer containing substantially no antimony element as both outer layers. The silicone transfer amount (100 ° C.) on the surface of the release layer is 4.0 kcps or less, the arithmetic average roughness (Ra (A)) of the surface of the release layer is 1 to 5 nm, and the other The arithmetic average roughness (Ra (B)) of the surface is 10 to 50 nm, and the ratio of the ten-point average roughness (Rz (A)) of the release layer surface to the arithmetic average roughness (Ra (A)) (Rz (A) / Ra (A)) is 3 to 10 in the release film.

  According to the present invention, in order to cope with miniaturization and high density of wiring, as a support for forming a film-like interlayer insulating material for a multilayer printed wiring board manufactured by a build-up method, releasability In addition, it is possible to provide a release film having good migration, blocking and surface smoothness, and the industrial value of the present invention is high.

  In the present invention, the polyester film constituting the release film is required to be composed of at least two layers. Furthermore, a three-layer structure may be used, and besides the above, four or more layers may be used as long as the gist of the present invention is not exceeded, and there is no particular limitation.

  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 usually 60 mol% or more, preferably 80 mol% or more of polyethylene terephthalate or the like which is an ethylene terephthalate unit.

  In the present invention, “substantially free of antimony element” specifically means that the amount of antimony metal element in the polyester is 10 ppm or less, preferably 5 ppm or less, and most preferably 0 ppm.

The polyester film of the present invention usually contains at least one compound selected from a titanium compound and a phosphorus compound. The titanium element content is usually 20 ppm or less, preferably 10 ppm or less, and more preferably 2 ppm or less.

  When there is too much content of a titanium compound, an oligomer byproduces in the process of melt-extruding polyester, and it may be impossible to obtain a film having low transparency and high transparency. On the other hand, the amount of phosphorus element is usually 1 ppm or more, preferably 5 ppm or more, and the upper limit is usually 300 ppm or less, preferably 200 ppm or less. By containing a specific amount of the above-described titanium and containing a phosphorus compound, it is possible to exert a remarkable effect on the reduction of the contained oligomer. When there is too much content of a phosphorus compound, gelatinization will occur and it may become a foreign material and cause the quality of a film to fall. In the present invention, when a titanium compound and a phosphorus compound are contained in the above-described range, by-production of oligomers can be prevented, and in the present invention, a remarkable effect can be exhibited.

  Further, the layer containing the titanium compound and the phosphorus compound preferably contains no antimony element, usually 100 ppm or less, preferably 60 ppm or less, more preferably substantially free, that is, 10 ppm or less, Preferably it is 0 ppm. When the amount of the antimony element in the polyester film is too large, there may be a problem such as generation of foreign matters due to aggregation or darkening of the film and loss of transparency during melt extrusion. Furthermore, the remaining antimony catalyst may crystallize and precipitate on the film surface to form protrusions.

  In the present invention, it is necessary to design a smooth film surface at a higher level. Therefore, the formation of protrusions derived from the compound containing the antimony element has conventionally been at a level that is not a problem at all, but with recent technological breakthroughs, it is difficult to cope with applications that require high smoothness was there. For example, in the release layer coating process, there are cases where repelling occurs or in the resin sheet molding application, there are problems such as impairing the smoothness of the surface of the interlayer insulating layer.

The polyester of the present invention may be obtained by a melt polymerization reaction, but if a raw material obtained by solid-phase polymerization of a polyester formed into a chip after melt polymerization is used, the amount of oligomers contained in the raw material is Since it can reduce, it is used preferably.

  The amount of oligomer contained in the polyester film is preferably 0.7% by weight or less, and more preferably 0.5% by weight or less. When the amount of oligomer in the polyester layer is small, the amount of oligomer contained in the polyester film of the present invention is reduced and the effect of preventing oligomer precipitation on the film surface is particularly high.

  In the present invention, a film having a structure in which a polyester having a low oligomer content is coextruded and laminated on at least one surface of a layer made of polyester having a normal oligomer content may be used. The effect of suppressing oligomer precipitation obtained in the present invention can be exhibited to a high degree.

In the present invention, it is preferable to blend particles in the polyester layer mainly for the purpose of imparting slipperiness. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like. Furthermore, during the polyester production process, it is possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed. On the other hand, the shape of the particles to be used is not particularly limited. Either a rod shape or a flat shape may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  Moreover, the average particle diameter of the particle | grains to be used is 0.01-3 micrometers normally, Preferably it is the range of 0.01-1 micrometer. When the average particle diameter is less than 0.01 μm, the particles are likely to aggregate and dispersibility may be insufficient. On the other hand, when the average particle diameter exceeds 3 μm, the surface roughness of the film becomes too rough and There may be a problem when a release layer is applied in the process.

  Furthermore, the particle content in the polyester layer is usually in the range of 0.001 to 5% by weight, preferably 0.005 to 3% by weight. When the particle content is less than 0.001% by weight, the slipperiness of the film may be insufficient. On the other hand, when the content exceeds 5% by weight, the transparency of the film is insufficient. There is.

  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.

  The thickness of the polyester film constituting the release film of the present invention is not particularly limited as long as it can be formed as a film, but is usually 12 to 250 μm, preferably 25 to 188 μm, and more preferably 38. It is in the range of ˜125 μm.

  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.

  The release layer constituting the release film in the present invention refers to a layer having releasability. Specifically, the peeling force (F) between the acrylic adhesive tape and the release layer is preferably 30 to 200 mN / cm, and more preferably 50 to 150 mN / cm. If the release force of the release film is outside the above range. In a scene that does not need to be peeled off, the release film may be peeled off easily, or in a scene that needs to be peeled off, a problem such as difficulty in peeling may occur.

  The release layer constituting the release film in the present invention can be provided on the polyester film by the above-described coating stretching method (in-line coating). The coating stretching method (in-line coating) is not limited to the following, but for example, in sequential biaxial stretching, the first stage of stretching may be completed and the coating treatment may be performed before the second stage of stretching. it can. When a release layer is provided on a polyester film by a coating and stretching method, the film can be applied simultaneously with stretching, and the thickness of the release layer can be reduced according to the stretching ratio. Can be manufactured.

  In addition, the release layer constituting the release film in the present invention is required to contain a curable silicone resin in order to improve the release property with respect to the interlayer insulating layer. It may be a type mainly composed of a curable silicone resin, or a modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin or an alkyd resin may be used as long as the gist of the present invention is not impaired. Also good.

  As the type of the curable silicone resin, any of the curing reaction types such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, a solventless type, a heat and ultraviolet curable combined type can be used. Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X manufactured by Shin-Etsu Chemical Co., Ltd. -62-1387, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62 -7213, YSR-3022, TPR-6700, TPR-6720, TPR-6720, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605, manufactured by Momentive Performance Materials Toray Dawkonin SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S, BY24-452, DKQ3-202, DKQ3-203, DKQ3-205, DKQ3-210, etc. Is exemplified. Further, a release control agent may be used in combination to adjust the release property of the release layer.

In the present invention, the curing conditions for forming the release layer on the polyester film are not particularly limited, and when providing the release layer by off-line coating, usually at 120 to 200 ° C. for 3 to 40 seconds, The heat treatment is preferably performed at 100 to 180 ° C. for 3 to 40 seconds as a guide. Moreover, you may use together heat processing and active energy ray irradiation, such as ultraviolet irradiation, as needed. In addition, a conventionally well-known apparatus and an energy source can be used as an energy source for hardening by active energy ray irradiation. The coating amount (after drying) of the release layer is usually from 0.005 to 1 g / m ² , preferably from 0.005 to 0.5 g / m ² , more preferably from 0.01 to 5 in terms of coatability. The range is 0.2 g / m ² . When the coating amount (after drying) is less than 0.005 g / m ² , the coating property may be less stable and it may be difficult to obtain a uniform coating film. On the other hand, when the coating is thicker than 1 g / m ² , the coating layer adhesion and curability of the release layer itself may be lowered.

  The release film of the present invention is peeled off after the interlayer insulating layer is bonded to the core base material as an adhesive sheet and finishes its role, but the interlayer insulating layer bonded to the core base material after release of the release film Affects the surface.

  The arithmetic mean roughness (Ra (A)) of the release surface of the release film used in the present invention needs to be in the range of 1 to 5 nm, preferably in the range of 1 to 3 nm. When Ra (A) is out of the above range, for example, after forming the interlayer insulating layer, the smoothness of the surface of the obtained insulating layer becomes insufficient, and it becomes difficult to deal with higher density circuits.

  In order to obtain a smoother interlayer insulating layer, the release film of the present invention has, as additional requirements, ten-point average roughness (Rz (A)) and arithmetic average roughness (Ra (A)) of the release surface. Ratio (Rz (A) / Ra (A)) must be in the range of 3-10, preferably 3-6. When the upper limit of the above range is exceeded, the surface roughness of the surface of the interlayer insulating layer, which is the opposite substrate bonded to the surface of the release film of the release film, is increased, resulting in a higher density circuit. It becomes difficult to cope with. On the other hand, when the lower limit of the above range is not reached, the surface of the release layer becomes extremely flat, resulting in problems such as blocking when the release film is rolled up.

  Furthermore, in the release film of the present invention, in consideration of the winding property or transportability of the film, the arithmetic average roughness Ra (B) of the surface (B surface) on which the release layer is not provided is 10 to 10. It needs to be 50 nm, preferably 15 to 30 nm. When Ra (B) is less than 10 nm, when the release film is wound up in a roll shape, problems such as blocking occur. On the other hand, when Ra (B) exceeds 50 nm, transfer of surface protrusions to the surface of the interlayer insulating layer, so-called show-through, occurs.

  In the release film of the present invention, the migration amount of the release layer surface at 100 ° C. (Si (100 ° C.)) is 4. 0 kcps or less, preferably 3.5 kcps or less. In the case where Si (100 ° C.) is out of the above range, problems such as a decrease in adhesiveness inherent in the interlayer insulating layer occur.

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

  Regarding the release film in the present invention, a coating layer such as an adhesive layer, an antistatic layer and an oligomer precipitation preventing layer may be provided on the surface where the release layer is not provided, as long as the gist of the present invention is not impaired.

  Further, the polyester film constituting the release film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

  Next, the interlayer insulating layer formed on the release surface of the release film in the present invention will be described below.

  The curable resin constituting the interlayer insulating layer in the present invention can form a resin layer on the release layer of a release film having a polyester film as a base material, and has sufficient insulation. It can be used without particular limitation. Specific examples include epoxy resins, acrylic resins, polyimide resins, polyimide amide resins, polycyanate resins, polyester resins, thermosetting polyphenylene ether resins, and the like. Two or more of these may be used in combination, or a multilayer structure may be used.

  In addition, the method of forming the interlayer insulating layer on the release layer of the release film is to apply the resin composition varnish in which the thermosetting resin or the like is dissolved in a solvent on the release surface and dry it, and at the same time, cure the resin. It can produce by a conventionally well-known method, such as the method of making it.

  In this invention, the curable resin layer used as an interlayer insulation layer is provided on the release film comprised from a polyester film base material, and it is set as a roll-shaped product. When it is a roll-shaped product, it may be in the roll state as it is, or may be in a state where a protective film is further bonded for the purpose of protecting the surface of the curable resin. Absent. Further, by protecting with a protective film, there is an advantage that it is possible to prevent dust from adhering to the surface of the interlayer insulating layer or to prevent scratches. The protective film to be used is not particularly limited as long as it has a function of protecting the surface of the interlayer insulating layer, and plastic films such as polyethylene, polypropylene, and polyester are used.

  The thickness of the interlayer insulating layer is preferably equal to or greater than the thickness of the conductor layer. Usually, the thickness of the conductor layer of the circuit board is preferably in the range of 5 to 70 μm, and the thickness of the resin composition layer is preferably 10 to 100 μm.

  As an example of a method for using the interlayer insulating layer thus obtained, when the circuit is formed by patterning the conductive layer, the protective film of the interlayer insulating layer is peeled off as an adhesive film and laminated on the core substrate. Heat treatment with the configuration of core substrate / interlayer insulating layer / release film or the configuration of release film / interlayer insulation / core substrate / interlayer insulating layer / release film with both sides of the core substrate sandwiched between interlayer insulating layers Etc., the core substrate and the interlayer insulating layer are adhered, and the support made of the release 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 preferably a pressure bonding temperature (lamination temperature) of preferably 70 to 140 ° C., a pressure bonding pressure of preferably 1 to 11 kgf / cm ^2, and lamination 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. In addition, a multilayer printed wiring board having a conductor layer (circuit) in which conductor layers and insulating layers are alternately formed and patterned on one or both sides is also included in the circuit board referred to in the present invention. 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.

  After laminating the adhesive film as the interlayer insulating layer on the circuit board in this way, the release film can be peeled off and thermally cured to form the insulating layer on the circuit board. The conditions for heat curing are selected in the range of 150 to 220 ° C. for 20 to 180 minutes, more preferably 160 to 200 ° C. for 30 to 120 minutes. After the insulating layer is formed, if the release film is not peeled before curing, 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. .

  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) Content of oligomer (cyclic trimer) in laminated polyester film constituting release film Chloroform / 1,1,1,3,3,3-hexafluoro-2-propanol (mixed) Ratio: 3/2) After being dissolved in the mixed solution, it was reprecipitated with chloroform / methanol (mixing ratio: 2/1) and filtered to remove linear polyethylene terephthalate, and then the solvent in the obtained filtrate was filtered. Then, evaporation was performed using an evaporator, and the obtained precipitate was dissolved in a predetermined amount of DMF. The obtained DMF was supplied to liquid chromatography (Shimadzu LC-2010C) to determine the amount of oligomer (cyclic trimer) contained in the polyester, and this value was divided by the amount of polyester used for measurement. The amount of oligomer (cyclic trimer) contained in. The amount of oligomer (cyclic trimer) determined by liquid chromatography was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method). The standard sample was prepared by weighing a preliminarily collected oligomer (cyclic trimer) and dissolving it in a weighed DMF (dimethylformamide). The conditions for the liquid chromatograph were as follows.

"Measurement condition"
Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: Shimadzu Corporation Shim-pack VP ODS
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(4) Measurement of arithmetic average roughness ((Ra (A), Ra (B)) of release film JIS-B-0601-1994 using a surface roughness measuring machine (SE-3500) manufactured by Kosaka Laboratory. From the film cross-section curve, a portion with a reference length L (2.5 mm) is extracted in the direction of the center line, and 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 the curve y = f (x), the value given by the following formula [Equation 1] is represented by (μm), and the arithmetic average roughness is 10 cross-sectional curves from the measurement surface of the sample film. The radii of the tip of the stylus was 2 μm, the load was 30 mg, and the cut-off value was 0.08 mm.
Ra = (1 / L) ∫ 0 L | f (x) | dx

(5) Ten point average roughness of release film (Rz (A), Rz (B))
Measurement is performed according to JIS-B-0601-1994 using a surface roughness measuring machine (SE-3500) manufactured by Kosaka Laboratory. In the part where only the reference length (2.5 mm) is extracted from the cross-section curve, the average value of the altitude of the highest to fifth peaks measured in the direction of the vertical magnification from the straight line that is parallel to the average line and does not cross the cross-section curve It represents the value (μm) of the difference from the average value of the altitude of the bottom of the valley from the deepest to the fifth. The measurement conditions were the same as in item (3).

(6) Peeling force (F) measurement of release film Affixed with one side of a double-sided adhesive tape (Nitto Denko “No. 502”) on the surface of the release layer of the sample film, then cut into a size of 50 mm × 300 mm Measure the peel force after standing at room temperature for 1 hour. For the peeling force, a tensile tester (“Intesco model 2001 type” manufactured by Intesco Co., Ltd.) was used, and 180 ° peeling was performed under a tensile speed of 300 mm / min.

(7) Release film peelability evaluation from interlayer insulation layer (practical property substitution evaluation)
<Resin composition varnish>
Liquid bisphenol A type epoxy resin (epoxy equivalent 180, “Epicoat 828EL” manufactured by Japan Epoxy Resin Co., Ltd.) 28 parts Naphthalene type tetrafunctional epoxy resin (“EXA-4700” manufactured by Dainippon Ink & Chemicals, Inc.) 28 parts Methyl ethyl ketone (Hereinafter abbreviated as MEK) 15 parts Cyclohexanone 15 parts

The composition was dissolved by heating. The following additives were sequentially mixed there.
Phenolic hardener Naphthalene structure novolak resin (“SO485”, 50% solid content by Toto Kasei Co., Ltd.)
110 parts Curing catalyst (manufactured by Shikoku Kasei Kogyo Co., Ltd., “2E4MZ”) 0.1 part Spherical silica (average particle size 0.5 μm, “SOC2” manufactured by Admatechs) 77 parts Core shell rubber particles (average Particle size 0.5 μm, “AC-3816N” manufactured by Ganz Kasei Co., Ltd.) 9 parts Phenoxy resin varnish (“YL6954BH30” manufactured by Japan Epoxy Resin Co., Ltd.) 27 parts. A resin composition varnish was prepared.

<< Application of resin composition varnish to release film: Formation of interlayer insulating layer >>
The resin composition varnish produced by the above method is applied on the release layer of the release film with a gravure coater so that the resin layer thickness (after drying) is 70 μm, and heat treatment is performed at 120 ° C. for 6 minutes, and the release film An interlayer insulating layer using as a support was prepared. Next, a polyolefin film (thickness 50 μm, M-6: manufactured by Tamapoly) was bonded to the surface of the insulating resin layer.

<Production of single-sided flexible substrate>
After peeling the polyolefin film from the laminated product composed of the release film / interlayer insulating layer / polyolefin film, on the rough surface side of the electrolytic copper foil (thickness 18 μm, F1-WS: manufactured by Furukawa Circuit Foil Co., Ltd.) The interlayer insulating layers were stacked and laminated at 90 ° C. and 0.5 MPa for 1 minute using a vacuum press to prepare a single-sided flexible substrate.

<Peeling the release film from the interlayer insulation layer>
Then, it determined by the following criteria regarding the peeling condition at the time of peeling a release film from an interlayer insulation layer.
<Criteria>
○: Smoothly peelable. (Practical, no problem level)
Δ: Slightly heavy, but peelable. (Practical level that may cause problems)
X: Difficult to peel off Or it peels easily. (Practical problem level)

(8) Measurement of application amount (Si) of release layer The following measurement conditions were measured by FP (Fundamental Parameter Method) method using a fluorescent X-ray measurement apparatus (Shimadzu Corporation, model “XRF-1500”). Below, the amount of silicon elements on the surface of the sample film provided with the release layer and the surface without the release layer was measured, and the difference was taken as the amount of silicon element in the release layer. Next, the coating amount (Si) (g / m ₂ ) as a unit of —SiO (CH ₃ ) ₂ was calculated using the obtained amount of silicon element.
"Measurement condition"
Spectral crystal: PET (pentaerythritol)
2θ: 108.88 °
Tube current: 95 mA
Tube voltage: 40 kv

(9) Quantification of the amount of metal element and phosphorus element in the laminated polyester film constituting the release film Fluorescence X-ray analyzer (model “XRF-1500” manufactured by Shimadzu Corporation) was used for the film FP method. The amount of elements in the film was determined by sheet measurement, and the detection limit in this method is usually about 1 ppm.

(10) Transferability evaluation of release film (Si (100 ° C))
The release surface of the sample film and an untreated PET film (Mitsubishi Resin Diafoil “T100 type-50 μm”) were laminated, and then subjected to a hot press treatment at 100 ° C., 10 kg / cm ² for 60 minutes. Thereafter, the amount of silicone from the release surface of the sample film to the surface of the untreated PET film was measured as described in (8). In addition, the silicon element amount of the sample film and untreated PET film to be used is measured in advance before the measurement.

(11) Evaluation of blocking property of release film After cutting the sample film into 10 cm square, 10 sheets are stacked so that the release surface and the surface where the release layer is not provided are combined, 100 ° C., 1 hour, 10 kg / cm After pressing under the condition of ² , the determination was made according to the following criteria.
<Criteria>
○: No blocking has occurred (a level that is practically acceptable)
X: Blocking occurs (when the sample samples are peeled apart, the feeling of peeling is clearly heavy, and there is a practically problematic level)

(12) Evaluation of smoothness of interlayer insulating layer surface (practical property substitution evaluation)
After peeling off the release film from the interlayer insulating layer obtained in the item (7), the surface of the interlayer insulating layer in contact with the release surface (measurement area: 1 m ² ) is contactless with a scanning laser microscope (Lasertec Corporation). The surface was observed according to the following judgment criteria.
<Criteria>
* Status of occurrence of craters (dents) with a depth of 0.5 μm or more ○: 1 crater (dent) with a depth of 0.5 μm or more on the surface of the interlayer insulating layer / m ² or less Δ: Depth of 0 on the surface of the interlayer insulating layer The number of craters (dents) of 5 μm or more exceeds 1 / m ² and is less than 3 / m ² .
X: Three or more craters (dents) having a depth of 0.5 μm or more on the surface of the interlayer insulating layer / m ² or more.

(13) Comprehensive evaluation Using the respective release films produced in Examples and Comparative Examples, comprehensive evaluation was performed according to the following criteria for each evaluation item of peelability, transferability, blocking property, and surface smoothness.
<Criteria>
○: Peelability, transferability, blocking property, and surface smoothness are all ○ (a level that causes no problem in practical use)
Δ: At least one of peelability, transferability, blocking property, and surface smoothness is Δ (a level that may cause a problem in practical use).
X: At least one of peelability, transferability, blocking property, and surface smoothness is x (practically problematic level)

The polyester used in the examples and comparative examples was prepared as follows.
<Manufacture of polyester>
Production Example 1 (Polyester A1)
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 and 0.02 part of tetrabutoxy titanate were added, and then the temperature was reached to 280 ° C. and the pressure to 15 mmHg in 100 minutes. It was 0.3 mmHg. After 4 hours, the inside of the system was returned to normal pressure to obtain a polyester having an intrinsic viscosity of 0.58.
Further, the obtained polyester was subjected to solid phase polymerization at 220 ° C. under vacuum to obtain polyester A1 having an intrinsic viscosity of 0.70.

Production Example 2 (Polyester A2)
Production Example 1 was conducted in the same manner as in Production Example 1 except that 1.2 parts of aluminum oxide particles having an average particle diameter of 0.7 μm were added, to obtain Polyester A2 having an intrinsic viscosity of 0.70.

Production Example 3 (Polyester A3)
Manufactured in the same manner as in Manufacture Example 2 except that the amount of aluminum oxide particles having an average particle size of 0.7 μm was changed to 1.8 parts in Manufacture Example 2 to obtain polyester A3 having an intrinsic viscosity of 0.70.

Production Example 4 (Polyester A4)
Manufactured in the same manner as in Manufacture Example 2 except that the amount of aluminum oxide particles added with an average particle size of 0.7 μm was changed to 2.4 parts in Manufacture Example 2 to obtain polyester A4 having an intrinsic viscosity of 0.70.

Production Example 5 (Polyester A5)
In Production Example 2, the same procedure as in Production Example 2 was conducted except that 0.3 part of silicon dioxide particles having an average particle diameter of 3.4 μm was added instead of adding 1.2 parts of aluminum oxide particles having an average particle diameter of 0.7 μm. The polyester A5 having an intrinsic viscosity of 0.70 was produced.

Production Example 6 (Polyester A6)
In Production Example 2, a polyester A6 having an intrinsic viscosity of 0.70 was obtained in the same manner as in Production Example 2 except that 0.03 part of tetrabutoxytitanate was added instead of 0.02 part of tetrabutoxytitanate. It was.

Production Example 7 (Polyester A7)
In Production Example 6, production was carried out in the same manner as in Production Example 6 except that 1.2 parts of aluminum oxide particles having an average particle size of 0.7 μm were additionally added to obtain Polyester A7 having an intrinsic viscosity of 0.70.

Production Example 8 (Polyester A8)
In Production Example 6, production was carried out in the same manner as in Production Example 6 except that 0.3 parts of silicon dioxide particles having an average particle size of 3.4 μm were additionally added, to obtain polyester A8 having an intrinsic viscosity of 0.70.

Production Example 9 (Polyester A9)
In Production Example 6, production was carried out in the same manner as in Production Example 6 except that 1.0 part of silicon dioxide particles having an average particle diameter of 3.4 μm was additionally added, and polyester A9 having an intrinsic viscosity of 0.70 was obtained.

Production Example 10 (Polyester A10)
In Production Example 1, production was carried out in the same manner as in Production Example 1 except that solid phase polymerization was not carried out to obtain Polyester A10 having an intrinsic viscosity of 0.58.

Production Example 11 (Polyester B1)
Starting from 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, magnesium acetate / tetrahydrate is added as a catalyst to the reactor, the reaction start temperature is set to 150 ° C., and the reaction temperature is gradually increased as methanol is distilled off. Was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. This reaction mixture was transferred to a polycondensation tank, 0.02 part of orthophosphoric acid was added, tetrabutoxy titanate was added, and a polycondensation reaction was performed for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.57 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure to obtain a polyester. The obtained polyester was subjected to solid phase polymerization at 220 ° C. under vacuum to obtain polyester (B1) having an intrinsic viscosity of 0.70.

Production Example 12 (Production of polyester film F1)
Polyester A2 and B1 are blended in proportions of 40% and 60%, respectively, as a surface layer (release surface side) material, polyester A1 = 100% material as an intermediate layer material, and the other surface layer (reverse mold) Surface side) Using raw materials blended with polyesters A5 and B1 at a ratio of 50% and 50%, respectively, as raw materials, supplied to three extruders with vents, melt-extruded at 290 ° C., and then applied electrostatically Amorphous film was obtained by cooling and solidifying on a cooling roll whose surface temperature was set to 40 ° C. using the method.

  The film was stretched 4.2 times in the machine direction at 85 ° C., then led to a tenter, stretched 5.2 times in the transverse direction at 120 ° C., heat-treated at 220 ° C. for 3 seconds, and then in the width direction at 180 ° C. 5% relaxation was added to obtain a polyester film F1 having a thickness of 38 μm (thickness ratio = 2 μm / 34 μm / 2 μm) and an oligomer (cyclic trimer) content of 0.42% by weight.

Production Example 13 (Production of Polyester Film F2) to Production Example 18 (Production of Polyester Film F7)
In Production Example 12, a polyester raw material was produced in the same manner as in Production Example 11 except that the polyester materials and blending ratios shown in Table 1 below were different, and each polyester film was obtained. Table 1 shows the properties of the obtained polyester films.

Example 1:
<Manufacture of release film>
After applying the following release agent composition to the polyester film F1 by a reverse gravure coating method so that the coating amount (after drying) is 0.1 g / m ² , heat treatment is performed at 120 ° C. for 30 seconds to release. A mold film was obtained.
<Releasing agent composition>
Curing type silicone resin (LTC750A: manufactured by Toray Dow Corning) 100 parts Curing agent (SRX212: manufactured by Toray Dow Corning) 2 parts Toluene / MEK mixed solvent (mixing ratio is 1: 1) 1500 parts The characteristics of the mold fill are shown in Tables 1-3.

Example 2:
In Example 1, except having changed a mold release agent composition into the mold release agent composition shown below, it manufactured like Example 1 and obtained the mold release film.
<Releasing agent composition>
Curing type silicone resin (LTC750A: manufactured by Toray Dow Corning) 100 parts Curing agent (SRX212: manufactured by Toray Dow Corning) 2 parts Peeling control agent (BY24-4980: manufactured by Dow Corning Toray) 10 parts Toluene / MEK mixed solvent ( The mixing ratio is 1: 1) 1500 parts

Example 3:
In Example 1, it manufactured similarly to Example 1 except using the polyester film F2 instead of the polyester film F1, and obtained the release film.

Example 4:
In Example 1, except having changed a mold release agent composition into the mold release agent composition shown below, it manufactured like Example 1 and obtained the mold release film.
<Releasing agent composition>
Curing type silicone resin (LTC303E: manufactured by Toray Dow Corning) 100 parts Curing agent (SRX212: manufactured by Toray Dow Corning) 2 parts Peeling control agent (BY24-4980: manufactured by Toray Dow Corning) 30 parts Toluene / MEK mixed solvent ( The mixing ratio is 1: 1) 1500 parts

Example 5:
Polyester A2 and B1 are blended in proportions of 40% and 60%, respectively, as a surface layer (release surface side) material, polyester A1 = 100% material as an intermediate layer material, and the other surface layer (reverse mold) Surface side) Using raw materials blended with polyesters A5 and B1 at a ratio of 50% and 50%, respectively, as raw materials, supplied to three extruders with vents, melt-extruded at 290 ° C., and then applied electrostatically Amorphous film was obtained by cooling and solidifying on a cooling roll whose surface temperature was set to 40 ° C. using the method.

The film was stretched 4.2 times in the longitudinal direction at 85 ° C., and then a release layer having the following release agent composition was applied so that the coating amount (after drying) was 0.06 g / m 2, and then applied to the tenter. Then, the film was stretched 5.2 times in the transverse direction at 120 ° C., heat-treated at 220 ° C. for 3 seconds, and then relaxed by 5% in the width direction at 180 ° C. to obtain a thickness of 38 μm (thickness ratio = 2 μm / 34 μm / 2 μm), and a release film having an oligomer (cyclic trimer) content of 0.42% by weight was obtained.
<Releasing agent composition>
Curing type silicone resin: DEHESIVE D400E (Asahi Kasei Wacker) 90% by weight
Cross-linking agent: V72 (Asahi Kasei Wacker) 10% by weight
The release layer composition was diluted with ion-exchanged water to prepare 10% by weight.

Example 6:
In Example 5, it manufactured like Example 5 except having changed the mold release agent composition into the following composition, and obtained the release film.
<Releasing agent composition>
Curing type silicone resin: DEHESIVE D430 (Asahi Kasei Wacker) 70% by weight
Curing type silicone resin: DEHESIVE D440 (Asahi Kasei Wacker) 20% by weight
Peel control agent: CRA491 (Asahi Kasei Wacker) 10% by weight
The release layer composition was diluted with ion-exchanged water to prepare 10% by weight.

Example 7:
In Example 1, it manufactured like Example 1 except using polyester film F10 instead of polyester film F1, and a release film was obtained. In addition, the oligomer amount in the used polyester film F10 was 0.62 weight%.

Comparative Example 1:
In Example 1, it manufactured like Example 1 except using polyester film F3 instead of polyester film F1, and obtained a release film.

Comparative Example 2:
In Example 1, except having changed a mold release agent composition into the mold release agent composition shown below, it manufactured like Example 1 and obtained the mold release film.
<Releasing agent composition>
Curing type silicone resin (LTC303E: manufactured by Toray Dow Corning) 100 parts Curing agent (SRX212: manufactured by Toray Dow Corning) 2 parts Toluene / MEK mixed solvent (mixing ratio is 1: 1) 1500 parts

Comparative Example 3:
In Example 1, it manufactured like Example 1 except having used polyester film F4 instead of polyester film F1, and obtained the release film.

Comparative Example 4:
In Example 1, it manufactured similarly to Example 1 except using the polyester film F5 instead of the polyester film F1, and obtained the release film.

Comparative Example 5:
In Example 1, it manufactured like Example 1 except not providing a release layer, and obtained the release film.

Comparative Example 6:
In Example 1, it manufactured similarly to Example 1 except using the polyester film F6 instead of the polyester film F1, and obtained the release film. In addition to the particles, formation of coarse protrusions derived from the antimony catalyst used in the polyester was confirmed on the surface of the release layer of the obtained release film. If it is the conventional release film, it is a level which does not become a problem at all, However, It becomes unsuitable when smoothness is required at a very high level like this invention.

Comparative Example 7:
In Example 1, it manufactured like Example 1 except having used polyester film F7 instead of polyester film F1, and obtained the release film.

  The characteristics of the release films obtained in the above Examples and Comparative Examples are shown in Table 1 and Table 2 below.

  The release film in the present invention can be suitably used, for example, as a film-like support for forming an insulating layer used in a build-up type multilayer printed wiring board in which conductor circuit layers and insulating layers are alternately stacked. .

Claims (1)

It is a film having a release layer containing a curable silicone resin on one side of a laminated polyester film composed of at least two layers, the polyester layer containing substantially no antimony element as both outer layers, and the surface of the release layer The silicone migration amount (100 ° C.) is 4.0 kcps or less, the arithmetic average roughness (Ra (A)) of the release layer surface is 1 to 5 nm, and the arithmetic average roughness (Ra (B)) is 10 to 50 nm, and the ratio (Rz (A) / Ra (R) between the ten-point average roughness (Rz (A)) of the release layer surface and the arithmetic average roughness (Ra (A)). A release film characterized in that A)) is 3-10.