KR20020052473A - Dry film photoresist - Google Patents

Abstract

The present invention is applied to a polyethylene terephthalate support and coated with a photosensitive polymer formed by adding an acrylic copolymer as a binding polymer and adding a photopolymerization monomer, a photoinitiator, a photosensitizer, a coloring agent, a plasticizer and a heat stabilizer to an arbitrary thickness, and The present invention relates to a dry film photoresist prepared by protective lamination with a film, which is a melt blended product of polyethylene terephthalate and polyester elastomer, which is applied as a protective film by applying a polyethylene terephthalate film having excellent surface properties but melt blending a polyester elastomer. By lowering the modulus of elasticity, when applied to a printed circuit board, lead frame, etc., it is possible to prevent process problems such as air mixing, and also to prevent sagging of the protective film in the process of peeling off the protective film.

Description

Dry film photoresist

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry film photoresist, and more particularly, to a dry film used for manufacturing a printed circuit board (PCB), a lead frame, and a ball grid array (BGA). The present invention relates to a dry film photoresist in which a molten blend of polyethylene terephthalate and polyester elastomer is applied as a cover film in a photoresist.

Since dry film photoresist, or photosensitive film, was developed in 1968 under the trade name `` RISTON '' by DuPont in the US, it has been used as an important material for current electrical and electronic industries, especially printed circuit boards and other processing. .

Printed circuit boards are used as the basis for connecting parts circuits to industrial electronic devices such as computers and electronic communication devices, as well as domestic consumer electronic device components, and film photoresists are used as breakthrough processing technology materials for their production.

Photosensitive screen printing ink is used as a photoresist material for the formation of circuits on printed circuit boards. However, film photoresist is essential for the production of printed circuit boards of double-sided and multilayer boards requiring high density and high reliability. Is being used.

This dry film photoresist is composed of three layers: a base film, a photosensitive layer, and a cover film.

Generally, the support film uses a polyester film such as polyethylene terephthalate, and its thickness is about 25 μm.

Such polyester support films are used as supports during the manufacture of the dry film photoresist, and the protective film serves as a protective covering to prevent dust and damage to the resist during handling.

Then, the photosensitive polymer layer is applied on the polyester film, and has a thickness of 15 to 100㎛ according to the purpose of use after the coating. The photosensitive layer has various compositions depending on the mechanical and chemical properties and processing conditions required for the film photoresist.

Specifically, the photosensitive polymer layer may include a multifunctional monomer that performs photopolymerization by light, a photoinitiator that induces radicals by light so that photopolymerization occurs, and a polymer binder that provides mechanical strength, tentability, and adhesion of the photopolymerization composition. polymer, and additives such as dyes, stabilizers, adhesion promoters, or inhibitors. These components are dissolved in a suitable solvent, applied to a polyester support film, and dried.

The photosensitive polymer as described above may also be used as a liquid itself, or a photosensitive layer made of a photocurable composition may be laminated between a light transmissive polyester film and a protective film for workability and contamination prevention.

To describe each composition in detail, the polyfunctional monomer should be photopolymerized by the initiator to be resistant to the developing solvent in the post process and to be removed from the stripping ingredient.

Typically, the polyfunctional monomer uses a compound having at least one α, β-ethylenically unsaturated bond. In addition, in view of photopolymerization, a compound having two or more acryloyl groups or methacryloyl groups in the molecule is preferable as the polyfunctional monomer. For example, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, Glycol diacrylate derivatives such as 1,4-butanedioldiacrylate, 1,5-pentanedioldiacrylate or 1,6-hexanedioldiacrylate; Ethylene or propylene oxide adducts of bisphenol A such as N , N' -methylenebisacrylamide or N , N' -benzylidenebisacrylamide; And three or more acrylics such as glycerin triacrylate, trimethylolpropane triacrylate, trimethylol ethane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate or dipentaerythritol hexaacrylate There is a compound having a rate or a methacrylate compound corresponding to the acrylate.

Photoinitiators are accompanied by the excitation of electrons by ultraviolet light and by themselves generate radicals or induce other compounds to generate radicals, allowing the polyfunctional monomers to polymerize. The photocuring rate of the composition depends greatly on the type and content of photoinitiator. Specific examples thereof include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether or benzyl; Alkyl benzophenones such as benzophenone, 4,4'-bis (diethylamino) benzophenone, chlorobenzophenone, 4,4'-dimethylaminobenzophenone or 4,4'-dichlorobenzophenone; Anthraquinones such as 2-ethylanthraquinone or 2- t -butylanthraquinone; And 4- (dialkylamino) benzoic acid alkyl esters or 2,4,5-triarylimidazole dimers and derivatives thereof, or robin dimers or robin dimers, leukotriphenylmethane dyes, triarylmethaneicos Dyes such as dyes and combinations thereof.

On the other hand, as the polymer binder, an organic polymer such as an acrylic polymer, a styrene polymer, polyvinyl acetate, ethylene vinyl acetate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, chlorinated polyethylene, chlorinated polypropylene, vinylidene chloride Polymers, polyesters, polyamides, polyurethanes, polyvinyl acetals, alkyd resins, phenolic resins, epoxy resins, cellulose acetates, nitrate screens, styrene-butylene copolymers, styrene-acrylonitrile copolymers, rubber chlorides or maleicane Vinyl copolymers of hydride, aromatic sulfonamide formaldehyde resins and the like can be used.

Additives include dyes, stabilizers, adhesion promoters and thermal polymerization inhibitors.

As the dye, leuco-based dyes are mainly used, and there are methyl violet, malachide green, crystal violet, and the like, and may be selected and added depending on the purpose.

On the other hand, as a protective film constituting the dry film photoresist, a polyolefin film having a thickness of about 25 to 30 μm is generally used, and the polyolefin film allows the adhesive photosensitive layer to be wound on a mandrel without sticking to each other, thereby forming a film photo. It plays an important role in manufacturing and transporting resists.

When using the dry film photoresist having the above structure, the protective film is peeled off, laminated on the dynamic layer plate, exposed to ultraviolet light (UV), exposed to light, and developed through image development. Let's do it.

In other words, when the dry film photoresist composition is laminated by coating or lamination on a metal surface or the like and irradiated with ultraviolet rays, the exposed portion is cured and the unexposed portion is removed by a suitable solvent to form a desired image.

The solvent is largely divided into water-soluble and water-insoluble.

Water-insoluble solvents are disadvantageous in terms of working environment, environmental pollution, and manufacturing cost, and photocurable compositions that develop with water-soluble solvents are increasing.

Alkali-developable photosensitive resist prepared from the dry film photoresist composition is removed from the protective film layer from the dry film photoresist, laminated on a copper plate and subjected to ultraviolet light exposure using a photomask film or the like, an alkaline aqueous solution of any concentration and temperature The unexposed portion is removed by using to form a photoresist image.

The process of forming the photoresist image by removing unexposed portions using an aqueous alkali solution is called development. At the time of development, the photosensitive layer of the unexposed portion is dissolved in 0.5-1.5 wt% sodium carbonate or potassium carbonate aqueous solution in a temperature range of 25-35 ° C. to form an image.

The method of manufacturing a printed circuit board includes a plating method and a tenting method according to the method. In the plating method, the plating solution and various additive chemicals must have plating resistance to prevent the dry film photoresist from being eroded and peeled off during plating on the substrate. In the tenting method, the elasticity of the dry film photoresist film itself is required. Lose.

On the other hand, the dry film photoresist acts as a resist covering the hole in order to protect the hole of any size which imparts conductivity to the upper and lower surfaces of the substrate from the etching solution.

In this case, developing conditions are developed by spraying with 0.5 to 1.5 wt% sodium carbonate or potassium carbonate aqueous solution at a temperature of 25 to 35 ° C., and FeCl ₂ , FeCl ₃ , CuCl ₂ , CuCl ₃ and Sufficient elasticity corresponding to the external stress of the dry film blocking the hole on a board | substrate is calculated | required with respect to the etching conditions in which etching liquid, such as ammonia sulfate, is injected.

By the way, the conventional alkali developable photosensitive film uses the polyolefin film like polyethylene as a protective film.

Polyethylene film has good flexibility, chemical resistance and releasability and is easy to remove when used as a protective film of a photosensitive resin composition. In addition, the coefficient of friction with polyethylene terephthalate is large, so there is little telescope when the product is wound up.

However, polyethylene has a high molecular weight gel (gel) during the polymerization, thereby resulting in fine projections, such as fish eyes, even fisheye after film formation.

Fisheye is often formed in the stretched polyethylene film with a size of 1 mm or more, and the number having a size of 0.3 mm or more has a value of 500 to 50,000 pieces / m 2, and 0.3 mm or less is produced innumerably. do.

Such fisheye is transferred to the photosensitive layer to cause air incorporation when laminating. In particular, as the thickness of the photosensitive resist becomes thinner, the influence by fisheye increases, which increases the probability of causing a defect.

In FIG. 1, the air mixing caused by the fisheye of the protective film is schematically described.

When laminating a polyethylene film 13 on which a fisheye 20 is formed to a copper clad laminate composed of an epoxy resin 32 and a copper 31 plate, the fisheye 20 is transferred to a fisheye 20 transferred to the photosensitive polymer layer 12. Therefore, air mixing occurs in the laminated surface with the copper plate 31.

According to the width and height of the fisheye, the size of air incorporation changes, and the thinner the thickness of the photosensitive resist is affected.

Air incorporation is caused by a number of factors in addition to the influence of the protective film. Substrate factors such as grooves and deep scratch marks present in the substrate, presence of pressed marks by foreign matter in the photosensitive resist, scratches and scratches of the laminator roll, and the like.

Not all of the air mixing generated as shown in FIG. 1 causes a failure, but causes a failure depending on the situation. If the air inlet portion is located at the boundary between the exposure and the unexposed, the inner layer process causes a circuit shrinkage, moreover, a circuit defect, and in the plating process, a circuit enlargement, and further a circuit short.

Therefore, the present applicant is to solve the problem that air mixing occurs during lamination due to poor surface characteristics of the polyolefin film used as a protective film in the manufacturing of the conventional dry film photoresist as described above and eventually cause a defect in the manufacturing of a printed circuit board By using polyethylene terephthalate film with excellent surface smoothness and low coarseness, the protective film can minimize the defects that occur during the application of printed circuit boards that require high resolution without affecting the resist properties. A dry film photoresist is prepared, and has been filed and patented (Domestic Patent No. 247,706).

In more detail, as the protective film, a polyethylene terephthalate biaxially oriented film satisfying the surface characteristics represented by the following Equation 1 was used.

3.0 nm ≤ SRa ≤ 50 nm,

50nm ≤ Spv ≤ 500nm,

300 ≤ Summit Density ≤ 20,000

Where SRa is the average roughness of the centerline measured by a non-contact 3D surface roughness meter, Spv is the difference in height from peak to valley, and Summit Density is 4 points per unit area (1 point is 2 micrometers x 2 micrometers) of protrusion numbers which have a height of 1 nm or more.

However, the polyester film including the polyethylene terephthalate film has a very high initial modulus compared to polyethylene. Therefore, unlike polyethylene, it is difficult to deform with a small stress, and elastic recovery does not easily occur after deformation.

Unlike conventional lead frame makers, when a conventional laminator machine structure of a printed circuit board (PCB) maker releases dry film from a roll for copper lamination, the protective film is peeled off the photoresist and wound on another roll. It has a structure in which two rolls are driven simultaneously on the same axis. Therefore, in the case of polyethylene protective film, if it is pasted on the photosensitive layer under stress, it is easy to remove because of the given stress in the above process, but when the polyethylene terephthalate film is used as the protective film, the initial elastic modulus is high, and the deformation is difficult. It was found that the protective film sag occurs in the process of peeling off the protective film due to poor elastic recovery.

The present inventors while trying to solve the problem in using the polyethylene terephthalate film as a protective film of the dry film photoresist as described above, the melt blended by mixing the polyester elastomer in the production of polyethylene terephthalate film As a result, it was found that the polyethylene terephthalate can exhibit the rubbery properties of the polyester elastomer while maintaining the surface properties thereof, thereby completing the present invention.

Therefore, an object of the present invention by using a melt blend of polyethylene terephthalate and polyester elastomer as a protective film due to the excellent surface properties significantly improve the defects due to fisheye, etc. while having a rubbery property to reduce the initial elastic modulus of the protective film It is to provide a dry film photoresist that can be floated.

The dry film photoresist of the present invention for achieving the above object is manufactured by sequentially stacking a polyethylene terephthalate-based protective film, a photosensitive polymer layer and a support film, wherein the polyethylene terephthalate-based protective film is a polyethylene alone or copolymerized It is characterized in that it is melt blended by mixing terephthalate and polyester elastomer.

FIG. 1 schematically shows the incorporation of air generated when laminating a dry film photoresist prepared using a conventional polyethylene film as a protective film on a copper clad laminate.

<Detailed Description of Drawing Major Symbols>

11-polyethylene terephthalate film 12-photosensitive polymer layer

13-polyethylene film 20-fisheye

31, 41, 51-copper 32-epoxy resin

The present invention will be described in more detail as follows.

In the dry film photoresist according to the present invention, a polyethylene terephthalate film having excellent surface smoothness and a small coarse protrusion is used as a protective film, but a melt blended mixture of polyester elastomer and polyethylene terephthalate is used to impart rubber properties. do.

The polyethylene terephthalate in the present invention is a polyethylene terephthalate alone or copolymerized, it is not particularly limited.

A polyester elastomer is mixed with such a single or copolymerized polyethylene terephthalate, wherein the polyester elastomer is obtained by copolymerizing terephthalic acid with butanediol and polytetramethylene glycol in the preparation of polybutylene terephthalate, that is, polybutylene It is a copolymer of terephthalate and polytetramethylene glycol, and specific types and thermal properties are shown in Table 1 below.

40D 55D 63D 72D Hardness (Shore D) 40 55 63 72 Furtherance Polybutylene Terephthalate (T) 1.0 1.2 1.8 1.8 Polytetramethylene glycol (kg) (wt%) 600 (60%) 500 (42%) 500 (28%) 200 (11%) Thermal properties Melting Point (℃) 173.8 197.56 209.45 219.49 Crystallization temperature (℃) 81.54 133.29 155.99 164.05 ΔHm 13.23 23.48 31.29 39.77

When the polytetramethylene glycol component of the polyester elastomer is increased, the hardness decreases, so that the properties of the elastomer are increased, and the adhesive strength is also increased due to the large polarity of the polytetramethylene glycol.

Even so, the content of the preferred polytetramethylene glycol component is 5 to 20% by weight of the total polyester elastomer. If the content of the polytetramethylene glycol component is less than 5% by weight of the total polyester elastomer, the effect of the addition is insignificant. If the content is more than 20% by weight, the compatibility with the polyethylene terephthalate is inferior, and the transesterification reaction is not easy to occur. The dispersion between the two polymers is poor. As a result, the surface roughness increases with the increase of haze, and aggregation of polyester elastomer similar to fisheye occurs.

When the polyester elastomer, which is a copolymer of polybutylene terephthalate and polytetramethylene glycol, is added during the production of the polyethylene terephthalate film, the surface properties of the polyethylene terephthalate are preserved, and the initial elastic modulus may be reduced by providing the rubber properties of the polyester elastomer. Can be.

It is preferable that the addition amount of a polyester elastomer at the time of mixing a polyethylene terephthalate and a polyester elastomer is 10-30 weight%. If the amount of the polyester elastomer added is less than 10% by weight in the total polyethylene terephthalate resin composition, the initial modulus is large and cannot be used as a protective film of a conventional dry film photoresist for a printed circuit board. On the other hand, if more than 30% by weight due to the polarity of the polytetramethylene glycol, the adhesion is increased, there is a problem that a large protrusion similar to fisheye due to phase separation occurs.

As described above, a biaxially stretched polyethylene terephthalate film is prepared after melt blending, and the surface roughness of the film is preferably the same as that of the polyethylene terephthalate film previously developed by the present applicant. It is desirable to be satisfied.

3.0nm≤SRa≤50nm

In the above formula, SRa represents the average roughness of the centerline measured by the non-contact 3D surface roughness meter.

If the surface roughness value of the film is increased, the possibility of coarse particles is increased and the surface area is increased, thereby increasing the adhesion between the supporting film and the adhesion between the photosensitive composition and the protective film, thereby torn the polyethylene terephthalate film as a support when the protective film is removed. Problems that the photosensitive layer itself is separated from the support film may occur.

When the SRa value is lower than 3.0 nm, a sudden increase in the friction coefficient may cause scratches, static electricity, and other process problems during the film manufacturing process and the dry film photoresist manufacturing process.

On the other hand, the thickness of the melt-blended biaxially stretched protective film of the polyethylene terephthalate and polyester elastomer of the present invention satisfying the above-described surface roughness value is preferably about 12 to 25㎛. If the thickness is thicker than 25㎛, the resilience of the biaxially stretched film is strong, so the loosening property is worsened during the lamination process when the product is used, and slip occurs.In case of thinner than 12㎛ It is disadvantageous for edge fusion.

As described above, a method of manufacturing a dry film photoresist using a melt blend of polyethylene terephthalate and a polyester elastomer as the protective film layer is in accordance with a conventional method, and there is no limitation in the structure of the support and the photosensitive polymer layer.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Preparation Example 1 Composition of Photosensitive Layer

The composition of the photosensitive polymer layer constituting the dry film photoresist is shown in Table 2 below.

The polymer binder was an acrylic copolymer prepared by combining 10% by weight acrylic acid, 15% by weight methacrylic acid, 60% by weight methyl methacrylate, and 15% by weight 2-ethylhexyl acrylate. However, this is only a method for helping understanding of the present invention, but the present invention is not limited thereto.

In the present invention, in addition to the above acrylic monomers, alkyl acrylates such as methyl acrylate, ethyl acrylate or propyl acrylate, alkyl methacrylate or propyl methacrylate, etc. You may use the acrylic copolymer manufactured from the combination of len and its derivative (s), phenoxymethylacrylate, 2-phenoxyethylacrylate, maleic acid, maleic anhydride, or vinyl acetate.

Photoinitiators, photopolymerizable monomers and other additives may be added freely without departing from the object of the present invention.

Photocurable Resin Composition Content (% by weight) Polymer binder 50.0 Photoinitiator Benzophenone 2.0 4,4'-bis (diethylamino) benzophenone 1.0 Loyco crystal violet 3.0 Toluene Sulphonic Acid Monohydrate 0.5 Diamond Green GH 0.5 Photopolymerizable monomer 9G 10 APG-400 10 BPE-500 10 menstruum Methyl ethyl ketone 13.0

Examples 1-3 and Comparative Examples 1-8: film forming of a protective film

Next, a film obtained by melt blending a biaxially stretched polyethylene terephthalate and a polyester elastomer prepared with the composition as shown in Table 3 was melt-extruded at a temperature above the melting point, and then rapidly cooled to a temperature below the glass transition temperature, and then biaxially stretched. Got it. Specific film forming conditions are as follows.

PEL type or polymer type Composition (PET / PEL) (wt%) Example One 72D 90/10 2 80/20 3 70/30 Comparative example One 63D 90/10 2 80/20 3 70/30 4 55D 80/20 5 40D 80/20 6 PET 100 7 PP 100 8 PE 100 PET: Polyethylene terephthalate PEL: Polyester elastomer PP: Polypropylene PE: Polyethylene

The films of the composition shown in Table 3 were subjected to sequential biaxial stretching while varying the lateral draw ratio and the longitudinal draw ratio from 3.0 times to 4.0 times, respectively, and the stretching temperatures were also sequentially biaxially stretched at 90 ° C. and 100 ° C. FIG.

In Table 4, haze for the stretching temperatures and the stretching ratios according to Examples 1 to 3 and Comparative Examples 1 to 5 were measured.

Haze was measured according to ASTM D-1003. Specifically, haze was measured using a haze meter (color and color difference meter) of Nippon Denshoku Kogyo Co., LTD.

Drawing temperature 90 ℃ 100 ℃ Drawing ratio (MD x TD) 3.0 × 3.0 3.5 × 3.5 4.0 × 4.0 3.0 × 3.0 3.5 × 3.5 4.0 × 4.0 Example One 4.0 3.7 3.6 10.9 5.5 4.9 2 10.1 4.4 4.1 27.4 25.2 24.4 3 10.4 6.6 5.3 20.3 17.1 16.8 Comparative example One 10.4 5.6 4.6 53.2 22.6 15.5 2 23.8 12.5 8.7 66.9 54.4 36.2 3 30.9 20.1 11.7 38.9 29.4 21.4 4 22.7 13.2 9.8 56.7 44.7 46.2 5 36.4 22.2 24.15 57.3 35.8 26.4

From the results of Table 4, when the temperature increases during stretching, the phase of the polyester elastomer added in small amounts due to the phase separation of the polyethylene terephthalate phase and the polyester elastomer phase under the stretching stress increases the haze and increases the surface roughness. It can be seen that the increase factor. In addition, it can be seen that as the draw ratio increases, the dispersing effect of the polyester elastomer in the dispersed phase increases and the haze falls.

On the other hand, the polyethylene terephthalate and polyester elastomer used in the present invention are both polyester-based and accompanied by a transesterification reaction when extruded at a high temperature, in the case of the polyester elastomer used in Comparative Examples 1 to 5 polytetramethylene glycol is carried out Compared to the examples, the amount of the polymers is not only low in compatibility, but also less easily transesterified, resulting in poor dispersion between the two polymers. As a result, the surface roughness increases with the increase of the haze, and the aggregation of the polyester elastomer similar to the fish eye also occurs.

On the other hand, in the following Table 5, the mechanical properties and surface roughness of the draw temperature 90 ℃, the draw ratio is 3.5 × 3.5 in the compositions of the examples and comparative examples were measured.

Here, tensile strength, elongation, and modulus are measured according to ASTM D-882, and specifically, using an Instron 1123 universal testing machine, elongation speed 300mm / min, distance between grips 100mm, 20 ° C, and 65% relative humidity, width 10mm. , 100 mm long specimens were used.

Surface roughness represents the average roughness (SRa) of the center line measured by a non-contact three-dimensional surface roughness meter. Specifically, the surface roughness is a value measured by the method according to the standard shown in JIS B0601. As a three-dimensional surface roughness meter, NT2000 model of WYKO Corporation is used. It was measured by.

Drawing ratio (MD x TD) Tensile Strength (kg / ㎡) Elongation (%) Modulus (kg / ㎡) F-5 value (kg / transfer ㎟) Surface Roughness (nm) Example One 3.5 × 3.5 17.75 167.1 126.4 1.272 35.1 2 14.66 182.4 100.1 1.157 30.8 3 12.19 202.5 96.31 1.012 38.1 Comparative example One 18.58 162.3 176.3 1.603 45.2 2 12.65 163.7 161.8 1.107 48.6 3 12.91 181.0 130.0 1.024 62.3 4 16.93 153.8 161.1 1.883 60.9 5 16.80 153.9 164.4 1.340 65.6 6 23.06 151.1 217.2 1.887 17.3 7 - 14.53 171.5 77.81 0.6412 35.1 8 - 2.252 253.5 20.63 0.2260 41.2

From the results in Table 5, it can be seen that Example 3 shows a similar level of modulus with low biaxially stretched polypropylene. In Comparative Examples 1 to 5, the physical properties of the polyethylene terephthalate constituting the matrix do not significantly decrease due to phase separation.

In the Examples, as shown in the present invention, the modulus was well reduced, and it was determined that the polyester elastomer in the disperse phase had good compatibility with the polyethylene terephthalate, which moderately prevented the crystallization of the polyethylene terephthalate. The physical properties of the embodiment, in particular, the modulus is very high compared to polyethylene but 1/3 of polyethylene terephthalate, and similar to that of biaxially stretched polypropylene, and can be applied as a protective film for dry film photoresist for printed circuit boards. It is a level that can be.

On the other hand, by comparing the adhesion between the protective film and the photoresist layer obtained according to the Examples and Comparative Examples are shown in Table 6.

Here, the evaluation of the adhesive strength was evaluated as the degree to which the photoresist layer is transferred to the protective film when the protective film is peeled off after coating the photosensitive resin composition obtained according to the preparation example on the biaxially oriented film obtained according to the Examples and Comparative Examples. .

Evaluation results Example One Similar level to polyethylene terephthalate 2 Similar level to polyethylene terephthalate 3 Similar level to polyethylene terephthalate Comparative example One Similar level to polyethylene terephthalate 2 Similar level to polyethylene terephthalate 3 Photoresist layer transferred to protective film 4 Photoresist layer transferred to protective film 5 Photoresist layer transferred to protective film

From the results of Table 6, it can be seen that as a result of the comparison of the adhesion between the protective film and the photoresist layer, the adhesion strength also increases as the component of polytetramethylene glycol having a greater polarity is increased. This increase in adhesive strength is not possible because it causes damage to the photoresist layer when the protective film is removed. In addition, the adhesion of Comparative Examples 1 and 2 is accompanied by an increase in haze due to phase separation or similarity with polyethylene terephthalate. Such phase separation increases surface roughness and has high modulus, so as a protective film for dry film photoresist for a printed circuit board. Can't use it.

After all, the most preferred composition is a protective film according to Example 2, but is not limited thereto.

In addition, according to the present invention, since the polyethylene terephthalate film is applied as a protective film, the defect rate such as short circuit or side etching is less during the post-processing. It seems to be alright.

As described in detail above, the dry film photoresist prepared by laminating a polyethylene terephthalate film mixed with melt blended polyester elastomer as a protective film as in the present invention is a fish eye or the like generated when a conventional polyethylene film is used as a protective film. When applied to printed circuit boards, lead frames and ball grid arrays (BGAs), there is little air mixing, and in addition to reducing defect rates such as short circuits and circuit losses, it is possible to apply polyethylene terephthalate film. It is possible to prevent the deformation of the protective film due to the high initial modulus of elasticity, which is a problem, and to prevent the protective film from sagging in the process of peeling off the protective film due to poor elastic recovery after deformation. Inexpensive alternative to printed circuit boards Dry film photoresists can be prepared.

Claims (6)

In the dry film photoresist prepared by sequentially stacking a polyethylene terephthalate-based protective film, a photosensitive polymer layer and a support film, The polyethylene terephthalate-based protective film is a dry film photoresist, characterized in that the melt blended or copolymerized polyethylene terephthalate and polyester elastomer. The dry film photoresist according to claim 1, wherein the polyester elastomer is a copolymer of polybutylene terephthalate and polytetramethylene glycol. The dry film photoresist according to claim 2, wherein the polytetramethylene glycol is added so as to be 5 to 20% by weight. The dry film photoresist according to claim 1, wherein the polyethylene terephthalate consists of 70 to 90% by weight and polyester polymer of 10 to 30% by weight. The dry film photo according to claim 1, wherein the surface roughness of the protective film satisfies a condition of 3.0 nm≤SRa≤50 nm (where SRa represents an average roughness of the centerline measured by a non-contact three-dimensional surface roughness meter). Resist. A dry film photoresist of which the modulus of the protective film is 130 kg / mm 2 or less as measured according to ASTM D882 at 23 ° C. and 50% RH.