JP2008239743A - Polyester film for dry film resist carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film for dry film resist carrier and corresponding to high resolution. <P>SOLUTION: A biaxially oriented polyester film for dry film resist carrier, having 5/m<SP>2</SP>number of depression defect having ≥0.5 μm depth, 70-150 MPa F-5 value in the longitudinal direction, 80-160 MPa F-5 value in the cross direction, ≤1% haze value, and 1.5-3.5% heat shrinkage in the longitudinal direction and 0.5-2.5% heat shrinkage in the cross direction each based at 150°C for 30 min, is provided thereby. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a biaxially oriented polyester film, specifically, excellent in transparency and excellent in slipperiness, especially for dry film resist supports used by laminating a photosensitive resin composition on one side. It relates to a polyester film.

  In recent years, dry film resists (hereinafter sometimes abbreviated as DFR) are often used as methods for producing printed wiring boards, semiconductor packages, flexible boards, and the like.

  A normal DFR has a sandwich structure in which a photosensitive layer (photoresist layer) is sandwiched between a polyester film as a support and a protective film (cover film) made of an LDPE film or the like. In order to produce a conductor circuit using this DFR, the following operations are generally performed.

    That is, the protective film is peeled off from the DFR and laminated with the substrate / conductive substrate layer so that the exposed surface of the resist layer and the surface of the conductive substrate layer such as copper foil on the substrate are in close contact with each other. . Next, the reticle on which the conductor circuit pattern is baked is placed on a support made of a polyester film, and from there, the resist layer mainly composed of a photosensitive resin is irradiated with ultraviolet rays (for example, I-line having a peak at 365 nm). And expose. Thereafter, after the reticle and polyester film are peeled off, unreacted components in the resist layer are dissolved and removed with a solvent. Next, etching is performed with an acid or the like to dissolve and remove the exposed portion in the conductive base material layer. As a result, the photoreactive portion in the resist layer and the conductive base material layer portion corresponding to the photoreactive portion remain as they are. Thereafter, if the remaining resist layer is removed, a conductor circuit on the substrate is formed.

  Since the conductor circuit is formed by such a method, the polyester film as the support is required to be able to transmit ultraviolet rays without interruption, and as a result, the circuit pattern baked on the reticle is accurately reflected on the resist layer. The

  Particularly, in recent years, with the miniaturization and weight reduction of OA equipment and IT equipment, there is a demand for a polyester film for a dry film resist support that has excellent transparency, low haze, and high resolution.

  However, since the polyester film usually contains particles as an easy-sliding material for imparting running properties and winding characteristics, light scattering by the particles is caused during the ultraviolet irradiation in the exposure process, and the resist There has been a problem of reducing the resolution.

  Accordingly, a polyester film for a dry film resist support, characterized in that the haze value of the film is lowered (for example, Patent Documents 1, 2, 3, and 5), or the transmittance at a wavelength of 365 nm is within a certain range. Has been proposed. Moreover, as a method for achieving these problems, it has been proposed to use a composite film, specific particles, particle average diameter, and particle content.

Further, in Patent Document 4, it is proposed to add particles having an average particle size of 0.001 to 0.5 μm having a Mohs hardness of 8 or more in order to suppress generation of wrinkles during film processing and generation of pattern defects during exposure. ing.
Japanese Patent Laid-Open No. 7-333853 JP 2001-264971 A JP 2002-043691 A JP 2002-341546 A JP 2005-059285 A

  However, even with the proposals described above, it is difficult to satisfy the demand for higher resolution in recent years, and defects such as distortion and omission in resist patterning after development cannot be solved sufficiently, and the degree of modification is still high. In view of the above-mentioned circumstances where demands for improving productivity such as quality improvement and yield continue, the present invention achieves high resist resolution, and has few defects, and can be used for quality improvement and productivity improvement. It aims at providing the polyester film for resist supports.

As a result of intensive studies to achieve the above object, the inventors of the present invention have reduced the resolution of the resist, in addition to the transmittance and haze of the film, the balance of strength in the longitudinal direction and the width direction of the film is important. It is necessary to make the thermal shrinkage rate within a specific range. In addition, defects such as distortion and omission in resist patterning after development are caused by depression defects existing on the surface of the polyester film for dry film resist support. It was also found that it is preferable to have a three-layer composite structure and to contain specific particles in the surface layer portion.
That is, according to the present invention, the number of recess defects having a depth of 0.5 μm or more is 5 / m ² or less, the F-5 value in the longitudinal direction is 70 to 150 MPa, and the F-5 value in the width direction is 80 to 160 MPa. The haze value is 1% or less, and the heat shrinkage rate at 150 ° C. for 30 minutes is 1.5 to 3.5% in the longitudinal direction and 0.5 to 2.5% in the width direction. It can be achieved by a biaxially oriented polyester film for a dry film resist support.

  According to the present invention, it is possible to provide a polyester film for a dry film resist support that can achieve high resolution of a resist, has few defects, and can cope with quality improvement and productivity improvement.

In the present invention, the number of recess defects having a depth of 0.5 μm or more is 5 / m ² or less, the F-5 value in the longitudinal direction is 70 to 150 MPa, and the F-5 value in the width direction is 80 to 160 MPa. The haze value is 1% or less, and the thermal shrinkage at 150 ° C. for 30 minutes is 1.5 to 3.5% in the longitudinal direction and 0.5 to 2.5% in the width direction. It is a biaxially oriented polyester film for a film resist support.

  Here, the polyester used for the biaxially oriented polyester is a polyester obtained by polymerization from a monomer having at least 70 mol% as a main component of an aromatic dicarboxylic acid and a diol.

  Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and terephthalic acid is particularly preferable. These acid components may be used alone or in combination of two or more, and may be partially copolymerized with other aromatic dicarboxylic acids such as isophthalic acid or fatty acids.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, and the like. Of these, ethylene glycol is preferably used. These diol components may be used alone or in combination of two or more.

  The polyester used in the laminated polyester film of the present invention is preferably polyethylene terephthalate, polyethylene naphthalate, and copolymers thereof, polybutylene terephthalate and copolymers thereof, polybutylene naphthalate and copolymers thereof, and further Examples include hexamethylene terephthalate and copolymers thereof, polyhexamethylene naphthalate and copolymers thereof, and polyethylene terephthalate is particularly preferable.

  The polyester used in the present invention can be produced by a conventionally known method. For example, a method in which an acid component is directly esterified with a diol component, and then the product of this reaction is heated under reduced pressure to perform polycondensation while removing excess diol component, or a dialkyl as an acid component A method of producing an ester by transesterifying it with a diol component and then performing polycondensation in the same manner as described above can be employed. At this time, conventionally known alkali metals, alkaline earth metals, manganese, cobalt, zinc, antimony, germanium, titanium compounds, and the like can be used as a reaction catalyst, if necessary.

  The biaxially oriented polyester film for dry film resist support of the present invention preferably has a total film thickness of 10 to 25 μm. Particularly preferably, the thickness is 12 μm to 20 μm. When the thickness is 10 μm or less, the strength is insufficient and handling in the processing step becomes difficult. Conversely, when the thickness exceeds 25 μm, it is difficult to make the light transmittance and haze value within the range of the present invention.

  In addition, the F-5 value in the longitudinal direction needs to be 70 to 150 MPa. If the F-5 value in the longitudinal direction is less than 70 MPa, the processing characteristics deteriorate due to scratches due to insufficient strength, and if it exceeds 160 MPa, it is difficult to achieve both the F-5 value in the width direction. Preferably, it is 70-140 MPa, More preferably, it is 80-130 MPa.

Furthermore, the F-5 value in the width direction needs to be 80 to 160 MPa. If the F-5 value in the width direction is less than 80 MPa, the processing characteristics due to the occurrence of scratches due to insufficient strength will deteriorate, and if it exceeds 160 MPa, it will be difficult to achieve both the F-5 value in the longitudinal direction. It is preferably 80 to 150 MPa, more preferably 90 to 140 MPa. The sum of the longitudinal F-5 value and the longitudinal F-5 value is preferably 200 to 270 MPa, and particularly preferably 220 to 250 MPa. preferable. Further, the F-5 value in the width direction is preferably equal to or greater than the F-5 value in the longitudinal direction, and the difference is more preferably 10 to 20 MPa.

  The breaking strength in the longitudinal direction is preferably 200 to 360 MPa, and more preferably 220 to 304 MPa. The breaking strength in the width direction is preferably 260 to 420 MPa, particularly preferably 280 to 400 MPa.

  The F-5 value and the breaking strength can be achieved by appropriately adjusting the stretching temperature and the stretching ratio in the longitudinal direction and the transverse direction.

The film of the present invention has a heat shrinkage rate at 150 ° C. for 30 minutes of 1.5 to 3.5% in the longitudinal direction and 0.5 to 2.5% in the width direction. When the heat shrinkage value in the longitudinal direction and the width direction is within this range, it is possible to suppress the occurrence of distortion and wrinkles due to heat shrinkage in the DFR processing step, and the heat shrinkage value at 150 ° C. for 30 minutes is 2-3% in the longitudinal direction. Furthermore, it is more preferable that it is 0.8 to 2.3% in the width direction.
The heat shrinkage value can be achieved by appropriately adjusting the relaxation heat treatment conditions in the film forming conditions.

  Furthermore, the light transmittance of the film of the present invention needs to be 85% or more. If it is less than 85%, it is insufficient to allow ultraviolet light to pass through without exposure, preferably 86% or more, and more preferably 88% or more.

  Further, the haze value of the film needs to be 1% or less. If it exceeds 1%, the scattering of ultraviolet rays during exposure increases, and the transmittance is impaired, which is not preferable. Preferably it is 0.8% or less, More preferably, it is 0.6% or less.

  In order to achieve the light transmittance and haze value within the scope of the present invention, it is necessary to suppress the light transmission inhibition by the contained particles and the like, and to further suppress the scattering due to the roughness and unevenness of the film surface. For this purpose, it is effective to reduce the particle size of the particles contained in the film and reduce the content. However, in this case, the film surface becomes too smooth and the slipperiness and running properties are poor. Thus, the processing characteristics are inferior. It is necessary to satisfy both contradictory functions of maintaining processing characteristics without deteriorating the total light transmittance and haze value.

  In order to achieve the above object, the surface layer contains organic particles having an average particle diameter of 0.2 to 0.7 μm with respect to the surface layer of 0.01 to 0.1% by weight. Ra) is preferably 3 to 10 nm.

Here, the three-layer structure is preferably composed of layers of A / B / A or A / B / C, and the particle types, average particle diameters, and contents contained in the A layer and C layer as the surface layer portion are different. May be. Furthermore, in the configuration of A / B / A, the laminated thickness on both sides may be different. More preferably, the structure of A / B / A is substantially the same, and the laminated thickness on both sides is substantially the same, and the particle composition is the same, so that the equipment structure can be simplified and productivity can be expected in the production of the film.
In the above configuration, the layer B preferably contains substantially no particles, and the layer A preferably contains particles, and the layer A has a thickness of 0.1 to 2 μm, preferably 0.2 to 1. 0.0 μm, more preferably 0.4 to 0.8 μm. When the particle size is less than 0.1 μm, the drop of the contained particles in the laminated portion becomes large. When the particle size exceeds 2 μm, it is necessary to further reduce the average diameter and added amount of the particles added to the A layer. It becomes difficult to achieve both.

  As the particles contained in the surface layer part A layer, organic and inorganic particles can be used. For example, silicon oxide, calcium carbonate, alumina, aluminum silicate, mica, clay, talc, barium sulfate, and the like are organic. Examples include polyimide resins, olefins or modified olefin resins, cross-linked polystyrene resins, and silicone resins. In adopting these particles, in order to suppress the increase in light transmittance and haze value, the surface of the particle is modified with a surfactant or the like, and the method of improving the affinity with the polyester is a method around the added particle. It can preferably be employed in terms of suppressing the generation of voids. Further, the particle shape is almost spherical and the difference in refractive index from the polyester is preferably smaller because it can suppress scattered light when ultraviolet rays pass through the film layer, and colloidal silica and organic particles are particularly preferable. Furthermore, silicone particles and crosslinked polystyrene particles are suitable.

  Among these, crosslinked polystyrene particles made of a styrene-divinylbenzene copolymer prepared by emulsion polymerization are preferable because the particle shape is close to a true sphere, the particle size distribution is uniform, and uniform protrusions can be formed.

  More specifically, organic particles having an average particle size of 0.2 to 0.7 μm are added to the surface layer part A layer in an amount of 0.01 to 0.1% by weight with respect to the surface layer, and the surface roughness (Ra) is 3 to 3. It is preferable to adjust to 10 nm. If the surface roughness is less than 3 nm, the running property is poor and the processing characteristics are inferior. If it exceeds 10 nm, an increase in haze value due to light scattering due to surface irregularities cannot be ignored. The surface roughness (Ra) is more preferably 4 to 8 nm.

  The surface roughness can be adjusted as appropriate depending on the average particle size and the amount of organic particles added to the surface layer A, but the preferred range is an average particle size of 0.2 to 0.7 μm, and the amount added is 0. 01 to 0.1% by weight. If the average particle size is out of this range, the haze value and light transmittance when the surface roughness is achieved are deteriorated due to the addition amount, which is not preferable. It is particularly preferable to add 0.01 to 0.05% by weight of organic particles having an average particle size of 0.3 to 0.5 μm.

In the film of the present invention, the number of depression defects having a depth of 0.5 μm or more is 5 pieces / m ² or less on both surfaces of the film. If the number of dent defects exceeds 5 / m ² , abnormal refraction of transmitted ultraviolet rays occurs at the time of exposure due to the dent, which may cause disturbance of the resist pattern and further increase the haze value locally.

  In the present invention, the dent defect means a fine recess on the film surface, and the depth is the maximum depth in the thickness direction from the film surface. It means the maximum depth from the bottom of the dent.

Although it is desirable to reduce the number of dent defects as much as possible, it is substantially a dent with a depth of 0.5 μm or more that substantially impedes the number of dent defects with a depth of 5 μm / m ² or more. This is achieved by the following. Preferably it is 3 pieces / m ² or less, more preferably 1 piece / m ² or less.

  The number of dent defects can be achieved by reducing the difference in speed at the contact place between the film and the roll during roll stretching and suppressing transfer of minute scratches on the roll. In particular, it is necessary to reduce deposits such as oligomers on the roll in order to suppress the transfer of scratches from the drawing roll. Frequent cleaning work on the roll and cleaning of the drawing zone to suppress oligomer adhesion Is effective.

  Furthermore, it is preferable to add agglomerated alumina together with the particles. Here, the aggregated alumina has an average primary particle diameter of 5 to 30 nm, preferably an average primary particle diameter of 8 to 15 nm aggregated from several to several hundreds. Those produced by hydrolysis of alcoside alumina can be employed. As this crystal type, δ type, θ type, γ type and the like are known, and in particular, δ type alumina can be preferably used. These agglomerated alumina can be used by adding at the time of polyester polymerization.For example, as a slurry of ethylene glycol, which is part of the raw material at the time of polyester polymerization, pulverization and dispersion of a sand grinder, etc. By carrying out, agglomerated alumina having an average secondary particle diameter of 0.01 to 0.2 μm can be obtained. When the agglomerated alumina thus obtained is added to the film, it is arranged in the plane direction by biaxial stretching, and unlike the above-mentioned projection-forming particles, it does not form substantial projections and affects the surface roughness. In addition, since the transparency is good, deterioration of light transmittance and haze value can be suppressed.

  By adding aggregated alumina, the effect of reinforcing the background of the film surface is great, the wear resistance is improved, and it is effective in suppressing the dent defect that occurs when contacting the roll during stretching. Aggregated alumina is preferably added to the surface layer, and its content is 0.1 to 1% by weight, preferably 0.2 to 0.9% by weight, and 0.6 to 0.8% by weight based on the surface layer. preferable.

    Next, the manufacturing method of the biaxially-oriented polyester film for dry film resist supports of this invention is demonstrated. As a method for incorporating inert particles into polyester, for example, high-precision that can collect 95% or more of coarse particles of 3 μm or more, for example, by dispersing inert particles in ethylene glycol, which is a diol component, at a predetermined ratio in the form of a slurry. After filtration, this ethylene glycol slurry is added at an optional stage prior to completion of polyester polymerization. Here, when adding the particles, for example, it is preferable to add the water sol or alcohol sol obtained at the time of synthesis without drying once because the dispersibility of the particles is good and the generation of coarse protrusions can be suppressed. Also effective for the effect of the present invention is a method in which a water slurry of particles is directly mixed with predetermined polyester pellets, supplied to a vent type twin-screw kneading extruder and kneaded into polyester.

    The particle-containing master pellets prepared in this way and pellets substantially free of particles, etc., are mixed at a predetermined ratio, dried, then supplied to a known melt laminating extruder, and the polymer is filtered through a filter. .

    Further, since a very small foreign matter also becomes a film defect, it is effective to use a high-accuracy filter that collects 95% or more of a foreign matter of 5 μm or more, for example. Subsequently, the sheet is extruded from a slit-shaped slit die and cooled and solidified on a casting roll to form an unstretched film.

  In other words, 1 to 3 extruders, 1 to 3 layers of manifolds or merging blocks (for example, merging blocks having a rectangular merging section) are stacked as necessary, sheets are extruded from the die, and cooled by casting rolls. To make an unstretched film. In this case, a method of installing a static mixer and a gear pump in the polymer flow channel is effective from the viewpoint of stabilizing the back pressure and suppressing thickness fluctuation.

The stretching method may be simultaneous biaxial stretching or sequential biaxial stretching.
In the case of sequential stretching, the first longitudinal stretching is important, and the stretching temperature is 90 to 130 ° C, preferably 105 to 120 ° C. When the stretching temperature is lower than 90 ° C., the film is easily broken, and when the stretching temperature is higher than 130 ° C., the film surface is easily damaged by heat, which is not preferable. Further, from the viewpoint of preventing uneven stretching and scratches, the stretching is preferably performed in two or more stages, and the total magnification is 3 to 4.5 times, preferably 3.2 to 4.2 times in the length direction. It is 3.2 to 5 times in the width direction, preferably 3.9 to 4.5 times. In order to achieve the target breaking strength of the film, a timely magnification can be selected, but in order to increase the breaking strength in the width direction, it is more preferable to set the stretching ratio in the width direction higher than in the longitudinal direction. If the temperature and magnification range are out of this range, problems such as uneven stretching or film breakage are caused, and it is difficult to obtain a film characterized by the present invention. After re-longitudinal or transverse stretching, heat setting is performed at 200 to 230 ° C., preferably 210 to 230 ° C. for 0.5 to 20 seconds, preferably 1 to 15 seconds. In particular, when the heat setting temperature is lower than 200 ° C., the crystallization of the film does not proceed, the structure is not stable, and the target characteristics such as heat shrinkage cannot be obtained. Thereafter, it is preferable to apply a relaxation treatment of 0.5 to 7.0% in the longitudinal and / or width direction.

    In the stretching process, contact between the film and the roll is unavoidable, and the difference between the peripheral speed of the roll and the speed of the film is suppressed as much as possible, and as the stretching roll, non-adhesive silicone that is easy to control the surface roughness and the like A roll is preferred. Although it is possible to use ceramics, Teflon (registered trademark) or metal rolls as in the prior art, only the film surface is locally heated and sticking occurs, which may cause scratches on the film surface. Yes, not preferred.

    Furthermore, the surface roughness Ra of the drawing roll is 0.005 to 1.0 μm, preferably 0.1 to 0.6 μm. When Ra is larger than 1.0 μm, unevenness on the roll surface during stretching is transferred to the film surface, which is not preferable. On the other hand, when it is smaller than 0.005 μm, the roll adheres to the film background, and the film is easily damaged by heat. It is not preferable. In order to control the surface roughness, it is effective to adjust the particle size of the abrasive, the number of times of polishing, etc. as appropriate, especially for the stretching roll, the degradation product of the polyester that is a cause of the dimple defects on the film surface, In order to avoid adhesion and accumulation of oligomers, frequent roll polishing is preferable.

    Further, the total contact time between the roll and the film in the stretching portion is 0.1 seconds or less, preferably 0.08 seconds or less, which is particularly effective in producing the film. When the contact time between the roll and the film is longer than 0.1 seconds, only the film surface is locally heated by the heat of the stretching roll, which may cause a deterioration in micro-planarity during heat load, or The film may be scratched, which is not preferable. As a method for shortening the contact time, for example, a method in which a film is stretched in parallel between nip rolls without being wound around a stretch roll is effective.

  Hereinafter, the present invention will be described in detail with reference to examples.

  The characteristic value measurement method and effect evaluation method of the present invention are as follows.

(1) Average particle diameter of particles The polymer is removed from the film by a plasma low-temperature ashing method to expose the particles. The processing conditions are selected such that the polymer is ashed but the particles are not damaged as much as possible. The particles are observed with a scanning electron microscope (SEM), and the particle image is processed with an image analyzer. The magnification of SEM is appropriately selected from about 5000 to 20000 times. The volume average diameter d is obtained by the following formula from the particle diameter and its volume fraction when the number of particles is changed to 500 or more by changing the observation location. When two or more kinds of particles having different particle diameters were contained, the same measurement was performed for each particle to obtain the particle diameter.
d = Σ (di · Nvi)
Here, di is the particle size, and Nvi is the volume fraction. When the particles are significantly damaged by the plasma low-temperature ashing treatment method, the film cross section is observed at 3000 to 100,000 times using a transmission electron microscope (TEM). The section thickness of the TEM is about 100 nm, the place is changed, 100 fields or more are measured, and the volume average diameter d is obtained from the above formula.

  The particle diameter of the aggregated alumina is observed at a magnification of 10,000 to 100,000 using a transmission electron microscope (TEM) as in the above. The section thickness of the TEM is about 100 nm, and 100 fields or more are measured from different locations, and the average diameter d of the equivalent circle diameter of the aggregated alumina to be observed is obtained.

(2) Intrinsic viscosity The value calculated by the following equation from the solution viscosity measured at 25 ° C in orthochlorophenol was used. That is,
ηsp / C = [η] + K [η] ² · C
Here, ηsp = (solution viscosity / solvent viscosity) −1, C is the weight of dissolved polymer per 100 ml of solvent (g / 100 ml, usually 1.2), and K is the Huggins constant (assuming 0.343). . The solution viscosity and solvent viscosity were measured using an Ostwald viscometer. The unit is indicated by [dl / g].

(3) Film Laminating Thickness The depth profile of the particle concentration is measured with XPS (X-ray photoelectron optical method), IR (infrared spectroscopy) or confocal microscope while etching from the surface. In the surface layer of the film laminated on one side, the particle concentration is low due to the air-resin interface called the surface, and the particle concentration increases as the distance from the surface increases. In the case of the film laminated on one side of the present invention, the particle concentration once reached the maximum value at the depth [I] starts to decrease again. Based on this concentration distribution curve, the depth [II] (here, II> I), which is ½ of the maximum particle concentration, was defined as the lamination thickness. Furthermore, when inorganic particles etc. are contained, using a secondary ion mass spectrometer (SIMS), the concentration ratio of the element resulting from the highest concentration of the particles in the film and the carbon element of the polyester Using (M + / C +) as the particle concentration, analysis in the depth (thickness) direction from the surface of the layer (A) is performed. Then, the laminated thickness is obtained from the same method as described above.

(4) F-5 value and breaking strength Measured using an Instron type tensile tester (Orientec Co., Ltd. film strength automatic elongation measuring device “Tensilon” universal testing machine RTC-1210). A 10 mm wide sample film was subjected to a tensile test under the conditions of a test length of 100 mm and a pulling speed of 200 mm / min. The stress when the film was stretched by 5% was defined as F-5 value, and the stress at the time of breaking was obtained to determine the breaking strength. It was. The measurement was performed at 23 ° C. and a humidity of 65% RH.

(5) Thermal contraction rate:
Two lines are drawn on the film surface so as to have a width of 10 mm and a measurement length of about 100 mm. The distance between the two lines is accurately measured at 23 ° C., and this is defined as L0. This film sample was left in an oven at 100 ° C. and 150 ° C. for 30 minutes under a load of 1.5 g, and then the distance between the two lines was measured again at 23 ° C., and this was defined as L1. Shrinkage was determined.
Thermal contraction rate (%) = {(L0−L1) / L0] × 100.

(6) Film surface roughness (Ra value)
It measured using the surface roughness measuring device (SE-3500 by Kosaka Laboratory). The measurement conditions are as follows.
Touch tip radius: 5 μm, needle pressure: 0.7 mN, measurement length: 4 mm, cut-off: 0.25 mm.

(7) Number of dimple defects On both sides of the film 10 m ² (for example, 1 m wide and 10 m long), the surface of the film is focused on bright spots based on light scattering using reflected light and transmitted light using a spotlight as a light source. Are examined with the naked eye, and the defect is marked with a pen. Further, a method of detecting a deflection disorder bright spot by crossed Nicols using a polarized light source is also used. For the marked defects, the maximum diameter of the dent is measured with a stereomicroscope, and the dent depth is measured for a dent with a maximum diameter of 3 mm or more using a stereo microscope with a mirro-type two-beam interference microscope (Nikon SMZ-10). Measurement was made to determine the number of recess defects having a depth of 0.5 μm or more and a maximum diameter of 3 mm or more. The depth of the dent was obtained by reading the disturbance of the interference fringes obtained at the obtained λ / 2 pitch with a microscopic eyepiece lens, as follows. The depth is the maximum depth in the thickness direction from the film surface. When a bulge occurs around the dent defect, the maximum depth from the top of the bulge to the bottom of the dent is obtained.
Depth = λ / 2 × (B / A)
λ: 546 nm
A: Reading value of λ / 2 by eyepiece
B: Disturbance amount of interference fringes.

(8) Surface roughness of stretching roll
Using a surface roughness meter Surf Test 301 manufactured by Mitutoyo Co., Ltd., the average roughness of the center plane was measured at three points in the roll width direction at a cutoff of 0.25 mm, and the average value was adopted.

(9) Light transmittance and haze value Measured according to JIS K7105-1981 using HZ-1 type manufactured by Suga Test Instruments Co., Ltd.

(10) Visual inspection of resist resolution The visual evaluation method of resist resolution by the biaxially oriented polyester film for dry film resist support was performed in the following procedure.

  (i) A negative resist “PMERN-HC600” manufactured by Tokyo Ohka Co., Ltd. was applied onto a 6-inch Si wafer that had been polished on one side, and rotated with a large spinner to form a resist layer having a thickness of 7 μm. Next, a pre-heat treatment was performed for about 20 minutes under a temperature condition of 70 ° C. using a ventilation oven with nitrogen circulation.

  (ii) Overlay the polyester film in contact with the resist layer, laminate the polyester film on the resist layer using a rubber roller, place a reticle patterned with chromium metal on it, Exposure was performed from above using an I-line stepper.

  (iii) After peeling the polyester film from the resist layer, the resist layer was placed in a container containing the developer N-A5 and developed for about 1 minute. Then, it removed from the developing solution and washed with water for about 1 minute.

  (iv) The state of L / S (μm) (Line and Space) of the resist pattern prepared after development was observed at a magnification of about 800 to 3000 using a scanning electron microscope SEM. The resolution of the resist was evaluated according to the following criteria.

    ○: L / S = 10/10 μm can be clearly confirmed.

    Δ: L / S = 10/10 μm cannot be clearly confirmed, but L / S = 15/15 μm can be clearly confirmed.

    X: L / S = 15/15 μm cannot be clearly confirmed.

(11) The friction coefficient between slippery films is in accordance with ASTM-D-1894-63, and the dynamic friction coefficient μd is measured using a surface measuring machine HEIDON-14DR manufactured by Shinto Kagaku Co., Ltd. The measurement was performed under the conditions of a load of 200 g and a contact area of 63.5 mm × 63.5 mm, and recorded and evaluated with an unraising recorder TYPE / HEIDON 3655E-99, and judged according to the following criteria. ○ and Δ can be used, and × is inferior in processing characteristics and rejected.

○: μd is less than 0.7 Δ: μd is less than 0.7 to 1.0 x: μd is 1.0 or more.

Example 1
To dimethyl terephthalate (DMT), 1.9 moles of ethylene glycol and magnesium acetate tetrahydrate per mole of DMT are added to 0.05 parts by weight of DMT and 0.015 parts by weight of phosphoric acid. Transesterification was performed, 0.025 parts by weight of antimony trioxide was subsequently added, the temperature was raised by heating and a polycondensation reaction was performed by evacuation to obtain homopolyester pellets having an inherent viscosity of 0.62, substantially containing no particles. .

  Further, an ethylene glycol slurry containing 10% by weight of δ-type alumina as agglomerated alumina is crushed and dispersed using a sand grinder, and further filtered using a 3 μm filter with a collection efficiency of 95%. It added to the transesterification reaction material adjusted similarly, followed by adding antimony trioxide, and performing polycondensation reaction, The master pellet of the intrinsic viscosity 0.62 containing 2 weight% of aggregated alumina was obtained.

  Further, an aqueous slurry of vinylbenzene / styrene copolymer crosslinked particles having an average particle size of 0.45 μm is contained in the above-mentioned homopolyester pellets substantially free of particles using a vented biaxial kneader, and 0 A master pellet containing 1% by weight of .45 μm divinylbenzene / styrene copolymer crosslinked particles based on the polyester was obtained.

  Next, a homopolyester containing substantially no particles was prepared as a raw material for the layer B (polyester B) so as to have a configuration of A / B / A. Further, homopolyester, aggregated alumina-containing master pellets and divinylbenzene / styrene copolymer crosslinked particle-containing master pellets were mixed as raw materials for layer A, and 0.7% by weight of aggregated alumina and 0.45 μm divinylbenzene / styrene copolymer were mixed. A polymer containing 0.03% by weight of crosslinked particles was prepared (Polyester A).

These polyesters A and B were each dried under reduced pressure at 160 ° C. for 8 hours, then supplied to separate extruders, melt-extruded at 275 ° C., filtered with high accuracy through a 5 μm filter, and then joined with a rectangular three-layer confluence block. Combined lamination was performed to form a three-layer laminate comprising polyester A / polyester B / polyester A. Thereafter, the film was wound around a casting drum having a surface temperature of 25 ° C. on a cooling roll through a slit die maintained at 285 ° C. by using an electrostatic application casting method, and solidified by cooling to obtain an unstretched laminated film. This unstretched laminated film was stretched by a sequential biaxial stretching machine at 110 ° C. in the longitudinal direction by 3.7 times and in the width direction by 4.1 times, respectively, for a total of 15.2 times. The film was stretched in the 05-fold width direction and heat-treated at 220 ° C. for 3 seconds under a constant length. Thereafter, relaxation treatment of 1% in the longitudinal direction and 2% in the width direction was performed to obtain a biaxially oriented polyester film having a total thickness of 16 μm and the thicknesses of the polyester A layers on both sides of 0.6 μm.
In the stretching step, a silicone roll having a surface roughness of 0.2 μm was used, and the total contact time between the roll and the film in the stretching portion was 0.06 seconds.
Tables 1 and 2 show the evaluation results of this film.

Examples 2-5, Comparative Examples 1-4
A biaxially oriented polyester film was obtained in the same manner as in Example 1 except that the particle diameter of the particles to be added, the addition amount, the addition amount of the particles to be added to the A layer, the thickness of the A layer, and the stretching conditions were changed.
The production conditions and evaluation results are shown in Tables 1 and 2.

Claims (3)

The number of dent defects having a depth of 0.5 μm or more is 5 / m ² or less,
F-5 value in the longitudinal direction is 70 to 150 MPa,
The F-5 value in the width direction is 80 to 160 MPa,
The haze value is 1% or less,
A biaxially oriented polyester film for a dry film resist support having a heat shrinkage of 150 to 30 ° C. for 30 minutes in the longitudinal direction of 1.5 to 3.5% and in the width direction of 0.5 to 2.5%. It consists of a three-layer structure, and the surface layer portion contains organic particles having an average particle diameter of 0.2 to 0.7 μm with respect to the surface layer of 0.01 to 0.1% by weight,
The biaxially oriented polyester film for a dry film resist support according to claim 1, wherein the surface roughness (Ra) is 3 to 10 nm. The biaxially oriented polyester film for a dry film resist support according to claim 2, wherein the surface layer contains 0.1 to 1% by weight of aggregated alumina particles.