JP4470599B2 - Dry film resist - Google Patents

Description

The present invention relates to a dry film resist (Dry Film Resist), details, good transparency in the ultraviolet region, moreover, relates to a dry film registry excellent in heat resistance. Hereinafter, the dry film resist may be abbreviated as DFR.

  Conventionally, the DFR method has been widely used as a method for producing printed wiring circuit boards and the like. As a DFR structure, a laminate in which a resist (photosensitive resin composition) layer is laminated on one side of a light-transmitting support film and a cover film made of polyethylene or polyester is provided thereon is generally used. An example of creating a printed wiring board using DFR is as follows.

  First, the cover film is peeled off, and the exposed resist layer is bonded to a printed wiring board making substrate. Next, the transparent substrate on which the electronic circuit pattern is printed is superposed on and closely adhered to the support film, and ultraviolet light is irradiated so as to transmit the support film from the transparent substrate side, thereby causing a curing reaction in the resist layer. . Next, after removing the transparent base material and the support film, a desired electronic circuit pattern is formed on the target base material by developing the resist layer.

  Therefore, since the DFR support film is required to have excellent mechanical strength as a support and high transparency, as well as heat resistance and solvent resistance, polyethylene terephthalate (hereinafter abbreviated as PET). A biaxially oriented film of an aromatic polyester represented by

  In general, the actinic radiation used for curing the photosensitive resin composition in the DFR method is often ultraviolet rays having a wavelength of 365 nm called i-line. Since this ultraviolet ray can be generated by a general-purpose high-pressure mercury lamp or metal halide lamp, there is an advantage that it can be handled with relatively inexpensive equipment.

  Incidentally, PET is an aromatic polyester having an aromatic ring in a molecular chain. Aromatic rings are thought to contribute to maintaining the rigidity of molecular chains and improving heat resistance and mechanical strength. However, aromatic rings in molecular chains impede UV transmission. It becomes a factor to do. Furthermore, in the case of a biaxially oriented film, since the aromatic ring is oriented parallel to the film plane, it has a weak point in which the transmittance of ultraviolet rays is further deteriorated.

As a prior art overcoming the above weak points, a biaxially oriented polyester film having a thickness of 12 to 25 μm is a laminated film provided with an easy-slip layer on one or both sides, and has a light transmittance of 86% or more at a wavelength of 365 nm. Some DFR polyester films have been proposed (see, for example, Patent Document 1).
JP 2002-62661 A

  However, even in the polyester film having the above-described configuration, when the polyester is PET, the light transmittance rapidly decreases in the wavelength region near 315 nm, and the light transmittance below 300 nm becomes substantially zero. By the way, the ultraviolet rays generated from the above-described high-pressure mercury lamp and metal halide lamp include an ultraviolet component having a shorter wavelength in addition to the aforementioned i-line. Specifically, such an ultraviolet component corresponds to a wavelength component in the region of 250 to 315 nm that cannot effectively transmit polyethylene terephthalate. Since ultraviolet rays in this wavelength region have high energy, productivity can be improved if they can be used for resist reactions. However, this is not possible with DFR using PET film. On the other hand, aliphatic polyesters having no aromatic ring in the molecule are generally excellent in transparency, but are often inferior in heat resistance, and only a small number can be formed into a biaxially stretched film.

The present invention has been made in view of the above circumstances, and its object is excellent in heat resistance, moreover, in the ultraviolet that could not be conventionally used wavelength shorter provide DF R that can be utilized.

  As a result of intensive studies, the present inventor has found that the above object can be easily achieved by using a biaxially oriented polyester having a specific composition and having specific physical properties for a support film. As a result, the present invention has been completed.

That is, the gist of the present invention is a dry film resist in which a resist layer is laminated on at least one side of a polyester film, and the polyester film has a proportion of units derived from 1,4-cyclohexanedicarboxylic acid in units derived from dicarboxylic acid. A biaxially oriented film composed of a polyester having a ratio of 95 mol% or more and a unit derived from 1,4-cyclohexanedimethanol in units derived from diol of 95 mol% or more and a melting point of 200 ° C or higher and 245 ° C or lower. there are, exist at the dry film registry, wherein the longitudinal direction and the width direction of shrinkage at 130 ° C. is both less than 5%.

The polyester film used in the DFR of the present invention has excellent heat resistance and excellent light transmittance at 270 to 315 nm. Therefore, in the DFR of the present invention , ultraviolet rays having a short wavelength can be used for the resist curing reaction, and the utilization efficiency of the ultraviolet rays can be increased.

Hereinafter, although the present invention will be described in detail, the description of the constituent elements described below is a representative example of the embodiment of the present invention, and is not limited thereto. The polyester film used in the DFR of the present invention is not an unstretched film or a film stretched only in a uniaxial direction, but biaxially stretched sequentially or simultaneously in the longitudinal direction and the width direction, and then heat-fixed biaxially oriented. It must be a polyester film.

The polyester which comprises a polyester film is a polycondensate which has as a main component the unit derived from 1, 4- cyclohexane dicarboxylic acid and the unit derived from 1, 4- cyclohexane dimethanol as a repeating unit. The main component referred to herein, repeating proportion of units derived from 1,4-cyclohexanedicarboxylic acid in a unit derived from a dicarboxylic acid is a unit 9 5 mol% or more, preferably 98 mol% or more, from diol It means that the proportion of units derived from 1,4-cyclohexanedimethanol in the unit is 95 mol% or more, preferably 98 mol% or more.

  Moreover, the ratio of the trans isomer of 1,4-cyclohexanedicarboxylic acid used as a raw material is usually 80 mol% or more, preferably 85 mol% or more, and the ratio of the trans isomer in 1,4-cyclohexanedimethanol is: Usually, it is 60 mol% or more, preferably 65 mol% or more. When the ratio of the trans isomer in the raw material is lower than the above range, the ratio of the trans isomer is lower than the above range even in the repeating unit in the obtained polyester.

  When the constituent ratio of the unit derived from dicarboxylic acid and the unit derived from diol and the ratio of the trans isomer in the raw material do not satisfy the above range, the resulting polyester has a low melting point, and the following range defined in the present invention Often not satisfied.

  Moreover, as long as it is in the component ratio range of said dicarboxylic acid-derived unit and diol-derived unit, the following other dicarboxylic acid-derived units and diol-derived units may be included. Examples of the other dicarboxylic acid include cis-isomer 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, oxalic acid, succinic acid, adipic acid, azelaic acid, sebacin. Examples thereof include aliphatic dicarboxylic acids such as acid and decanedicarboxylic acid. Examples of other diols include cis-isomer 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, pentane. Aliphatic diols such as diol and hexanediol are exemplified.

  In the present invention, for producing the polyester, for example, a conventionally known method of performing a polycondensation reaction after the ester reaction can be employed. The obtained polyester is extracted into water in the form of a strand and then pelletized.

The polyester used for the support film needs to have a melting point of 200 ° C. or higher, a preferable melting point is 210 ° C. or higher, and an upper limit is 245 ° C. When the melting point is less than 200 ° C., the heat resistance of the polyester is insufficient, and the heat setting temperature after biaxial orientation cannot be set high. As a result, the shrinkage rate of the biaxially oriented polyester film increases, and when heated in post-processing, wrinkles, sagging, undulations, etc. occur and the flatness of the film deteriorates.

  Regarding the degree of polymerization of the polyester, the intrinsic viscosity measured at 30 ° C. in a mixed solvent of phenol-tetrachloroethane (weight ratio 1: 1) is usually 0.55 dl / g or more, preferably 0.60 dl / g or more. It is. By satisfying such conditions, it is possible to prevent continuity during film formation and a decrease in mechanical strength of the film formed. The upper limit of the intrinsic viscosity is usually 1.5 dl / g.

  To the polyester constituting the polyester film, fine particles substantially inert to the polyester can be added in order to impart slipperiness to the film and improve handling during processing. As the fine particles, those that do not deteriorate the transparency of the polyester film as much as possible are suitably selected. Such fine particles are appropriately selected from inorganic particles, organic salt particles, and crosslinked polymer particles.

  Specific examples of the inorganic particles include calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, lithium fluoride, kaolin, and talc. Specific examples of the organic salt particles include terephthalate such as calcium oxalate, calcium terephthalate, magnesium terephthalate, and barium terephthalate. Specific examples of the crosslinked polymer particles include crosslinked polystyrene resins, crosslinked acrylic resins, crosslinked polyester resins, copolymers thereof, thermosetting resins such as epoxy resins, urea resins, and phenol resins, and fluorine-containing systems. Resin etc. are mentioned. These fine particles may be used alone or in combination of two or more.

  The average particle diameter of the fine particles is usually 0.05 to 4 μm, preferably 0.1 to 3 μm. The amount added to the polyester is usually 0.005 to 1% by weight, preferably 0.01 to 0.5% by weight. In addition, a predetermined amount of fine particles may be added to the polyester from the beginning, or a high concentration master batch is prepared, and a polyester containing substantially no fine particles is added thereto to dilute the predetermined amount. You may employ | adopt the method of setting it as the amount of particles.

The polyester film used in the DFR of the present invention may have a single layer structure in the thickness direction, but may be a coextruded film obtained by laminating at least two layers, preferably three or more layers during melt extrusion. In particular, when the laminated structure is three or more layers, there are two surface layers and an intermediate layer. However, there is a case where the above-described fine particles are added only to the surface layer and the fine particles are not added to the intermediate layer or added to the intermediate layer. By suppressing the added amount to 1/2 or less of the surface layer, deterioration of transparency can be minimized and slipperiness can be improved. In this case, the thicknesses of the two surface layers may be the same or different. The total thickness of the two surface layers is preferably selected in the range of 0.5 to 5 μm. However, all the polyesters of each layer constituting these laminated films must satisfy the melting point range described above.

  In addition, a known additive can be added to the polyester constituting the polyester film without departing from the gist of the present invention. Such additives include antioxidants, heat stabilizers, colorants, antistatic agents, lubricants, flame retardants, and the like.

The film haze of the polyester film used in the DFR of the present invention is usually 3% or less, preferably 2% or less. When the film haze exceeds 3%, the scattering of light passing through the film increases, and the resolution tends to deteriorate when the resist is exposed.

The light transmittance at 300 nm of the polyester film used in the DFR of the present invention is usually 70% or more, preferably 75% or more, and more preferably 80% or more. This is because, in high-pressure mercury lamps and metal halide lamps often used for ultraviolet curing, the specific energy of the wavelength component of 300 to 320 nm is abundant, and if the light transmittance of the polyester film at 300 nm is good, this wavelength component This is because the ultraviolet rays can be effectively used for curing the resist. Further, the light transmittance at 270 nm is usually 60% or more, preferably 65% or more, from the viewpoint of utilization of ultraviolet rays having higher energy.

The Young's modulus in the longitudinal direction and the transverse direction of the polyester film used in the DFR of the present invention is not particularly limited, but is preferably 1.0 GPa or more. When the Young's modulus is less than 1.0 GPa, when the support film is peeled off from the resist layer after being exposed to ultraviolet rays or the like, there is a tendency that the film easily stretches. The upper limit of Young's modulus is usually 2.5 GPa.

The shrinkage ratio in the longitudinal direction and the width direction at 130 ° C. of the polyester film used in the DFR of the present invention needs to be 5% or less. When the thermal shrinkage rate exceeds 5%, the polyester film is used as the support film, and when the resist is applied on the polyester film and dried, or when DFR is heat laminated to a copper-clad substrate, the support film There is a problem that the shrinkage becomes remarkable, and the flatness is easily deteriorated due to distortion or wrinkles in the support film, and the influence thereof also affects the resist. The shrinkage rate is preferably 4% or less, more preferably 3% or less.

  Further, the thickness unevenness in the longitudinal direction and the width direction of the polyester film is usually 15% or less, preferably 10% or less, and more preferably 5% or less.

Although the thickness of the polyester film used by DFR of this invention is not specifically limited, Usually, it is the range of 5-50 micrometers.

The polyester film used in the DFR of the present invention can be provided with a coating layer on at least one side for the purpose of adjusting the adhesion with the resist layer. This coating layer may be a coating layer coated on a film that has been biaxially oriented and heat-fixed to complete the crystal orientation, but the crystal orientation is completed in the film-forming process for producing the polyester film. A so-called in-line coating method in which one side or both sides of the previous polyester film is subjected to a corona discharge treatment if necessary, and then a coating solution mainly containing water is coated, and then stretched in at least one direction and further heat-set. The coating layer coated in (1) is more preferable in terms of productivity and strong adhesion between the coating layer and the biaxially oriented polyester film. This coating layer preferably contains at least one of a polyurethane resin, a polyester resin, a poly (meth) acrylate resin, a polyvinyl resin, a fluorine-containing resin, a modified product and a mixture thereof. In addition, instead of providing a coating layer on the film surface, it is also possible to perform actinic ray treatment such as corona discharge treatment.

The polyester film used in the DFR of the present invention can be used as a DFR by laminating a photosensitive resin composition (resist) layer on at least one surface and, if necessary, a cover film.

  As said photosensitive resin composition, what contains a base polymer, an ethylenically unsaturated compound, and a photoinitiator is preferable. In particular, in the present invention, a wavelength shorter than the ultraviolet ray used for normal exposure is also effectively used, but this short wavelength ultraviolet ray is mostly absorbed near the surface of the photosensitive resin composition and penetrates into the inside. May not. In order to prevent this as much as possible, a compound containing an aromatic ring is not used for the base polymer and the ethylenically unsaturated compound in the photosensitive resin composition, or the weight fraction of the aromatic ring is 10 even if it is used. % Or less (preferably 5% or less).

  As the base polymer, an acrylic copolymer produced from (meth) acrylic acid and (meth) acrylic acid ester is preferable in order to impart alkali developability. Here, as the (meth) acrylic acid ester, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, dimethylamino Examples include methyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, and the like. In addition to these, (meth) acrylamide, (meth) acrylonitrile, vinyl acetate, alkyl vinyl ether, styrene, vinyl toluene and the like may be copolymerized.

  The content of (meth) acrylic acid in the raw material of the acrylic base polymer is usually 15 to 45% by weight, preferably 20 to 35% by weight. When the content of (meth) acrylic acid is small, the resulting acrylic base polymer may be swollen and peeled when the resist is peeled off.

  A polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, or the like can be used in combination with the above base polymer. In addition, the weight average molecular weight of the base polymer is usually 40,000 to 200,000. If the molecular weight is too small, cold flow is likely to occur. Conversely, if the molecular weight is too large, development is difficult and resolution is deteriorated. Resulting in poor dispersibility at the time of resist stripping.

  Examples of the ethylenically unsaturated compound contained in the photosensitive resin composition include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and butylene glycol. Di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexane glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate , Pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, polyethylene Unless it already exists glycol diacrylate, and a polyfunctional monomer such as polypropylene glycol diacrylate.

  An appropriate amount of a monofunctional monomer can be used in combination with the above polyfunctional monomer. Examples of monofunctional monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, glycerin mono (meth) acrylate, N-methylol (meth) acrylamide, etc. Is mentioned.

  The ratio of the ethylenically unsaturated compound to 100 parts by weight of the base polymer in the photosensitive resin composition is usually 10 to 200 parts by weight, preferably 40 to 100 parts by weight. If the proportion of the ethylenically unsaturated compound is too small, curing failure, lowering of flexibility, delay of development speed is caused, and if the proportion of the ethylenically unsaturated compound is too large, increase in tackiness, cold flow, The peeling speed of the cured resist is reduced.

  Photoinitiators contained in the photosensitive resin composition include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, dibenzoyl, dibenzoyldimethyl ketal, methyl-o-benzoyl. Benzoate, diacetyl, anthraquinone, naphthoquinone, benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4-dimethylaminobenzophenone, 4-diethylaminobenzophenone, 4-dimethylaminoacetophenone, 4-diethylaminoacetophenone, 2,2-diethoxyacetophenone, pt-butyldichloroacetophenone, hexaarylimidazo Dimer, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, phenylglyoxylate, α-hydroxyisobutylphenone, N-phenylglycine, N-methyl-N-phenylglycine, etc. Illustrated. The blending ratio of the photopolymerization initiator is usually in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the total amount of the base polymer and the ethylenically unsaturated compound.

  For the resist layer used in the present invention, in addition to the acrylic base polymer, the ethylenically unsaturated compound and the photopolymerization initiator, a dye, an adhesion promoter, a thermal polymerization inhibitor, and a plasticizer are used as necessary. Antioxidants can be added.

  The above photosensitive resin composition is coated and laminated on the above-described polyester film as a support film. Conventionally used methods can be applied to this coating. That is, a typical example is a method in which a photosensitive resin composition dissolved in a solvent is applied onto a support film and then dried in an oven or the like. Thereafter, a polyethylene film, a polypropylene film, a polystyrene film, a polyester film, etc. are coated as a cover film on the coated photosensitive resin composition layer to obtain a DFR laminate. As long as the above characteristics are not impaired, other layers may be provided between the support film, the photosensitive resin composition layer and the cover film.

  In addition, the pattern mask used when forming an image by the above DFR is made of a commonly used PET film or soda glass plate, so that short wavelength ultraviolet rays of 300 nm or less are blocked. It is difficult to make full use of the features. Therefore, it is preferable to draw the target circuit pattern directly on the DFR support film. It is also preferable to use a pattern mask in which a circuit pattern is drawn on a material that transmits ultraviolet rays of 300 nm or less. Materials that transmit ultraviolet rays of 300 nm or less are made of materials such as quartz glass, fluorine-containing resin, amorphous polyolefin, polypropylene, polyvinyl alcohol, acetylcellulose, ethylcellulose, and acrylic resin, and are transparent and absorb ultraviolet rays. A substrate (film, sheet, plate) to which no agent is added can be used.

  Moreover, it is also possible to use the polyester film used as a support film by this invention as a mask film. Furthermore, this mask film can be used not only as a DFR method but also as a mask film for a liquid resist method, for example.

  Usually, exposure of DFR in the present invention is performed by ultraviolet irradiation, and as a light source at that time, a carbon arc lamp, a xenon arc lamp, an ultrahigh pressure mercury lamp, a chemical lamp, etc. can be used. In order to make use of it, it is preferable to use a high pressure mercury lamp, medium pressure mercury lamp, metal halide lamp or the like containing a short wavelength ultraviolet component of 315 nm or less.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example, unless the summary is exceeded. In the examples and comparative examples, “parts” means “parts by weight”. The measuring method used in the present invention is as follows.

1. Polyester melting point (Tm):
Using a differential scanning calorimeter (“DSC-2920” manufactured by TAInstuments), the temperature was measured at a heating rate of 20 ° C./min, and the temperature at the top of the endothermic peak accompanying crystal melting was taken as the melting point.

2. Average particle size of fine particles:
The equivalent spherical diameter of the particles at the 50% by weight point of all particles determined by the light scattering method was used as the average particle diameter.

3. Film haze value:
Using an integrating sphere turbidimeter (“NDH2000” manufactured by Nippon Denshoku Co., Ltd.), the haze value (%) was determined according to JIS K 7136 (2000) (equivalent to ISO 14782 1999).

4). Light transmittance:
Using a spectrophotometer (“UV-3100PC” manufactured by Shimadzu Corporation), the light transmittance was measured by continuously measuring the light transmittance from 200 to 400 nm and reading the values of 300 nm and 270 nm.

5). Young's modulus:
Using a tensile tester (“Intesco Model 2001” manufactured by Intesco), a sample film having a length of 300 mm and a width of 20 mm is placed at a speed of 25 mm / min in a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH. And using the first linear part of the tensile stress-strain curve, the following calculation was performed.

6. Thermal contraction rate of film at 130 ° C .:
In the longitudinal direction and the width direction of the film, a distance of about 50 mm was accurately measured (L1), and heat treatment was applied in an oven at 130 ° C. for 10 minutes in a tensionless state. Thereafter, the film was cooled, the distance between the marks was measured again accurately (L2), and the change between the marks before and after the heat treatment was calculated using the following formula to obtain a heat shrinkage rate of 130 ° C.

7). Film thickness irregularity:
It measures along the longitudinal direction and the width direction of a polyester film with a continuous film thickness measuring instrument (an electronic micrometer manufactured by Anritsu Electric Co., Ltd.), and the 1 m length is calculated by the following formula.

Example 1:
<Creation of polyester raw material A>
Into a reactor equipped with a stirrer, a distillation pipe and a pressure reducing device, 184 parts by weight of 1,4-cyclohexanedicarboxylic acid (1,4-CHDA) (trans mol 98 mol%), 1,4-cyclohexanedimethanol (1 , 4-CHDM) (67 mol% of trans isomer) 158 parts by weight, 0.9 part by weight of a 6% by weight butanol solution of Ti (OC ₄ H ₉ ) ₄ was charged and heated to 150 ° C. under a nitrogen flow. The temperature was raised to 1 ° C. over 1 hour. Thereafter, the esterification reaction was carried out by maintaining at 200 ° C. for 1 hour, and then the polycondensation reaction was carried out while gradually raising the pressure in the reactor from 200 ° C. to 250 ° C. over 45 minutes. After polymerization for 2 hours at a reactor internal pressure of 0.1 kPa (absolute pressure) and a reaction temperature of 250 ° C., the resulting polymer was drawn into water as a strand and then pelletized. The intrinsic viscosity of this polyester was 0.85 dl / g. The melting point was 220 ° C.

<Creation of polyester raw material B>
The polyester raw material A is dry blended with 0.4% by weight of divinylbenzene crosslinked polystyrene particles having an average particle diameter of 1.1 μm, and is charged into a twin-screw extruder with a vent, at a vacuum of 1 kPa (absolute pressure). The mixture was melted and mixed while removing moisture, extruded into a strand, cooled in water, and pelletized again. The intrinsic viscosity of this polyester was 0.82 dl / g. The melting point was 220 ° C.

<Made of polyester film>
Polyester A and polyester B were mixed at a weight ratio of 9: 1 and charged into a surface layer extruder. Apart from this, 100% by weight of polyester A was fed into an extruder for the intermediate layer. Each extruder is a twin screw extruder with a vent, and without extruding the resin, extruding at a melting temperature of 250 ° C. while removing moisture from the vent port at a vacuum of 1 kPa (absolute pressure). went. Each extruder is equipped with a gear pump and a filter. The melted polymer that has passed through them is merged and laminated in a feed block and extruded from a T-die. It was created. At this time, the thicknesses of both surface layers were the same, and the total thickness of both surface layers was set to be 20% of the total thickness. At this time, the film was cast on a cooling drum at 20 ° C. by applying an electrostatic application adhesion method.

  The obtained unstretched sheet was led to a longitudinal stretching process. A roll stretching method was used for longitudinal stretching, preheating to 70 ° C. with a plurality of rolls, and stretching in the longitudinal direction at a stretching ratio of 3.0 using an infrared heater. Next, this uniaxially stretched film was guided to a tenter, preheated at 70 ° C., and then stretched in the width direction at a stretch ratio of 3.0. After that, heat setting treatment was performed at 180 ° C. under tension in the same tenter, and biaxially oriented polyester film for a support film having a total thickness of 20 μm and biaxial orientation for a mask film having a total thickness of 10 μm. An oriented polyester film was obtained. Table 1 shows the characteristics of the support film.

<Creation of photosensitive resin composition>
A copolymer having a weight average molecular weight of 70,000 obtained from a composition of methyl methacrylate / 2-hydroxyethyl methacrylate / 2-ethylhexyl acrylate / methacrylic acid (weight ratio: 58/10/10/22) as a base polymer solution A 40 wt% methyl ethyl ketone / isopropyl alcohol (weight ratio: 50/50) solution was used, and the components described in Table 1 below were doped into this to prepare a photosensitive resin composition.

<Create DFR>
The above dope was applied on a biaxially stretched polyester film for a support previously formed using an applicator with a gap of 250 μm, and then dried in an oven at 60 ° C., 80 ° C., and 100 ° C. for 3 minutes, A resist layer having a thickness of 30 μm was formed. Further, a DFR was obtained by coating a 25 μm thick polyethylene film on the resist layer.

<Creation of mask film>
A 10 μm thick biaxially oriented polyester film formed for use as a mask film is subjected to corona discharge treatment and then printed with a negative image of a circuit pattern (pattern having a line width and a space width of 100 μm each). It was.

<DFR sensitivity>
After peeling off the DFR polyethylene film, a resist layer was laminated on the copper-clad substrate using a laminator. At this time, the copper-clad substrate was preheated to 60 ° C., and the laminate roll was set to a temperature of 100 ° C. and a roll pressure of 3 kg / cm ³ . Next, the mask film was placed on top of the resist support film so as not to contain air bubbles, and was exposed to light with a high-pressure mercury lamp. At this time, using a negative film ("Storfer 21-step tablet") made so that the amount of light transmission decreases step by step so that the photosensitivity can be evaluated, a sample with the exposure amount changed stepwise The sensitivity of the resist was evaluated based on the amount of energy necessary for the number of remaining steps after development to be 8 (the smaller the amount of energy, the better the sensitivity). The development was carried out by peeling the polyester film after 15 minutes from the exposure, and spraying a 1% by weight aqueous sodium carbonate solution at 30 ° C. for 50 to 60 seconds to remove unexposed portions. The results are shown in Table 2.

Comparative Example 1:
<Creation of polyester raw material C>
Polyester raw material except that 1,4-cyclohexanedicarboxylic acid (trans isomer: 98 mol%) is used instead of 1,4-cyclohexane dicarboxylic acid (trans isomer: 98 mol%) in the production of polyester raw material A of Example 1. Polymerization was carried out in exactly the same manner as in the production of A to prepare a polyester raw material C. This polyester had an intrinsic viscosity of 0.84 dl / g. The melting point was 192 ° C.

<Creation of polyester raw material D>
Polyester raw material C is dry blended with 0.4% by weight of divinylbenzene cross-linked polystyrene particles having an average particle size of 1.1 μm, put into a twin screw extruder with a vent, and moisture is removed at a vacuum of 1 kPa. Then, the mixture was melt-mixed and extruded into a strand shape, cooled in water, and pelletized again. The intrinsic viscosity of this polyester was 0.81 dl / g. The melting point was 192 ° C.

<Made of polyester film>
Polyester C and polyester D were mixed at a weight ratio of 9: 1 and charged into a surface layer extruder. Separately from this, 100% by weight of polyester C was charged into an extruder for the intermediate layer. Thereafter, the same operation as in Example 1 was performed, and melt extrusion, casting, longitudinal stretching, and transverse stretching were performed. Then, heat setting was performed at 160 ° C. under tension in the same tenter to obtain a biaxially oriented polyester film having a total thickness of 20 μm. The properties of this support film are shown in Table 2.

<Preparation of photosensitive resin composition and DFR>
A dope of the photosensitive resin composition was prepared in exactly the same manner as in Example 1, and this was applied in the same manner as in Example 1 on the biaxially oriented polyester film for support prepared above. Thereafter, the dope was dried in the same manner as in Example 1. However, the flatness due to heat shrinkage was remarkably deteriorated, and a usable DFR could not be produced.

Comparative Example 2:
<Polyester raw material E>
According to a conventional method, terephthalic acid (TPA) and ethylene glycol (EG) were subjected to a polycondensation reaction to obtain polyethylene terephthalate having an intrinsic viscosity of 0.71 dl / g and a melting point of 256 ° C.

<Polyester raw material F>
Polyester raw material E is dry blended with 0.4% by weight of divinylbenzene cross-linked polystyrene particles with an average particle size of 1.1 μm, put into a twin screw extruder with a vent, and moisture is removed at a vacuum of 1 kPa. The mixture was melt-mixed and extruded into strands, and cooled in water to prepare a master batch of particles. This polyester had an intrinsic viscosity of 0.68 dl / g. The melting point was 256 ° C.

<Made of polyester film>
Polyester E and polyester F were mixed at a weight ratio of 9: 1 and charged into a surface layer extruder. Apart from this, 100% by weight of polyester E was introduced into the extruder for the intermediate layer. Thereafter, the melting temperature is 280 ° C., the longitudinal stretching preheating temperature is 83 ° C., the longitudinal stretching ratio is 3.5 times, the transverse stretching preheating temperature is 100 ° C., the transverse stretching ratio is 3.7 times, and the heat setting temperature is 220 ° C. Except for this, melt extrusion, longitudinal stretching, transverse stretching, and heat setting were performed in the same manner as in Example 1 to obtain a biaxially oriented polyester film having a total thickness of 20 μm. The properties of this support film are shown in Table 2.

<Preparation of photosensitive resin composition and DFR>
A dope of the photosensitive resin composition was prepared in exactly the same manner as in Example 1, and this was applied in the same manner as in Example 1 on the biaxially oriented polyester film for support prepared above. Thereafter, the dope was dried in the same manner as in Example 1 to form a resist layer having a thickness of 30 μm. Further, a DFR was obtained by coating a 25 μm thick polyethylene film on the resist layer.

<Mask film>
A mask film similar to the mask film used in Example 1 was used.

<DFR sensitivity>
Resist sensitivity was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Claims (1)

A dry film resist in which a resist layer is laminated on at least one side of a polyester film, wherein the polyester film has a proportion of 1,4-cyclohexanedicarboxylic acid-derived units in dicarboxylic acid-derived units of 95 mol% or more, derived from diol A biaxially oriented film comprising a polyester having a unit ratio of 1,4-cyclohexanedimethanol in a unit of 95 mol% or more and a melting point of 200 ° C. or more and 245 ° C. or less , and having a longitudinal length at 130 ° C. dry film registry, wherein the direction and the width direction of the shrinkage are both 5%.