[DESCRIPTION]

[invention Title]

FILM TYPE TRANSFER MATERIAL

[Technical Field] The present invention relates to a film type photosensitive transfer material.

[Background Art]

Typically, a film type photosensitive transfer material is provided in the form of a dry film (hereinafter, referred to as "dry film photoresist") .

The dry film photoresist is used for a printed wiring board, a printed circuit board (PCB) , IC packaging, a metal relief sculpture and so on, and generally includes a base film, a photosensitive resin layer and a cover film. The base film plays a role in supporting the photosensitive resin layer and enabling the photosensitive resin layer which is adhesive to be easily handled in an exposure process. The photosensitive resin layer is prepared to be adapted for end use from a photopolymerizable monomer, a photoinitiator, and a binder polymer. The cover film is formed on the surface of the photosensitive resin layer opposite the surface where the base film is formed, and is thus responsible for preventing

damage to the photosensitive resin layer.

An example of a process of forming a pattern using such a dry film photoresist includes the fabrication of a PCB composed of removing a cover film from a dry film photoresist, laminating the dry film photoresist on a copper clad laminate (CCL) , placing a mask having a desired pattern on the dry film photoresist, performing an exposure process using UV light, and then performing a development process for washing out an uncured portion using an appropriate solvent. Typically, as shown in FIG. 3, the exposure process is conducted in a state in which the base film 40 is attached to the photosensitive resin layer 20. In this case, because the mask 60 is spaced apart from the photosensitive resin layer 20 by a thickness of the base film 40, the resolution may be lowered. Accordingly, the exposure process may be carried out after the base film is removed. If so, however, the mask may adhere to the photosensitive resin layer which is adhesive, because of the absence of the base film, undesirably damaging the photosensitive resin layer, thereby resulting in lowered resolution. Hence, it is actually difficult to conduct the exposure process after removal of the base film, and thus a problem in which the resolution is lowered still remains .

Further, with the advancement of techniques for increasing the density of PCBs and mounting semiconductor package thereon, the spacewidth of circuits becomes

smaller, and there is thus urgently required a film type photosensitive transfer material having high resolution which is applicable to a fine circuit substrate.

[Disclosure] [Technical Problem]

Accordingly, the present invention provides a film type photosensitive transfer material, which enables an exposure process to be performed even in the absence of a base film. In addition, the present invention provides a film type photosensitive transfer material, in which an interval between a mask and a photosensitive resin layer is minimized upon an exposure process, thus increasing the resolution, and also provides a display substrate having a pattern formed using the same.

[Technical Solution]

According to an embodiment of the present invention, a film type photosensitive transfer material includes a base film, a resin protective layer, a photosensitive resin layer and a cover film, wherein the resin protective layer has adhesion of 0.005 kgf/cirf or less, in which the adhesion is defined as a force per unit area required to separate an additional polyethyleneterephthalate (PET) film, which has been laminated on the resin protective layer exposed due to

removal of the base film, from a position of 5 cm to a position of 8 cm distant from a release starting point of the PET film.

In the transfer material according to the embodiment of the present invention, the resin protective layer may be an alkali developable polymer layer.

In the transfer material according to the embodiment of the present invention, the resin protective layer may have solubility of 5 g or less in methylethylketone at 25 ^° C, in which the solubility is defined as a decrement in weight of the resin protective layer as a result of an operation of adding 50 g of the resin protective layer to 100 g of methylethylketone, performing stirring at 25 ^° C for 1 hour and filtration using filter paper, and measuring the weight of the resin protective layer remaining on the filter paper.

In the transfer material according to the embodiment of the present invention, the resin protective layer may be formed from a coating solution including a water-soluble polymer having a weight average molecular weight of 5,000-300,000.

In the transfer material according to the embodiment of the present invention, adhesion between the cover film and the photosensitive resin layer may be smaller than adhesion between the base film and the resin protective layer. Also, the resin protective layer may have a thickness of 0.001-10 jMn.

In the transfer material according to a preferred embodiment of the present invention, the resin protective layer may have an adhesion change of 5000% or less as represented by Equation 1 below. Equation 1

, „ . ,_,, .. .. Second Adhesion - First Adhesion . . .

Adhesion Change (%) = x 100

First Adhesion wherein the first adhesion is defined as a force per unit area required to separate an additional polyethyleneterephthalate film, which has been laminated on the resin protective layer shortly after removal of the base film, from a position of 5 cm to a position of 8 cm distant from a release starting point of the polyethyleneterephthalate film, and the second adhesion is defined as a force per unit area required to separate an additional polyethyleneterephthalate film, which has been laminated on the resin protective layer, from a position of 5 cm to a position of 8 cm distant from a release starting point of the polyethyleneterephthalate film, the resin protective layer being prepared by removing the base film therefrom and allowing the resin protective layer to stand for 240 hours under conditions of temperature of 25 ^° C and humidity of 50%.

In the transfer material according to the preferred embodiment of the present invention, the resin protective layer may be a polyvinylalcohol-based resin layer. As such, the resin protective layer may include at least one additive

selected from among a wetting agent, a leveling agent, an antifoaming agent, a binder, and an adhesive.

In the transfer material according to the embodiment of the present invention, the cover film may be a polyester film with or without a release layer.

In the transfer material according to the embodiment of the present invention, the base film may be a polyester film with or without a release layer.

In an exemplary embodiment of the present invention, a display substrate, which has a pattern formed using the aforementioned film type photosensitive transfer material, is provided.

[Advantageous Effects] The present invention can provide a film type photosensitive transfer material and a display substrate. When the film type photosensitive transfer material according to the present invention is used, an exposure process can be performed after removal of a base film, and thus an interval between a mask and a photosensitive resin layer can be narrowed upon the exposure process, thereby further improving the resolution of a pattern.

In addition, the film type photosensitive transfer material according to the present invention allows the base film to be removed before the exposure process, and can be processed in sheets or can be applied to a roll-to-roll

process without damage to the photosensitive resin layer.

In addition, because an exposure process is performed directly after removal of the base film in the present invention, the process of the present invention is simpler compared to a conventional process including performing an exposure process, eliminating impurities and removing a base film, and also, the manufacturing cost of the display substrate can be reduced.

[Description of Drawings] FIG. 1 is a cross-sectional view showing the layer structure of a film type photosensitive transfer material according to a preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a display substrate including the film type photosensitive transfer material according to the present invention, upon an exposure process;

FIG. 3 is a cross-sectional view showing a display substrate including a conventional film type photosensitive transfer material having a three-layer structure, upon an exposure process;

FIG. 4 is a 80Ox magnified electron microscope image showing the surface of a PCB after a development process, manufactured in the example of the present invention; FIG. 5 is a 60Ox magnified electron microscope image

showing the surface of a PCB after a development process, manufactured in the comparative example; and

FIGS. 6 to 8 are (150Ox, 200Ox, 250Ox magnified) electron microscope images showing the surfaces of PCBs after a development process, manufactured in Examples 5 to 7, respectively.

* Description of the Reference Numerals in the Drawings * 10: cover film

20: photosensitive resin layer 30: resin protective layer 40: base film

50: flexible copper clad laminate (FCCL) 60: mask

[Best Mode] Hereinafter, a detailed description will be given of the present invention.

FIG. 1 illustrates a film type photosensitive transfer material according to an embodiment of the present invention. The film type photosensitive transfer material according to the present invention has a structure including a cover film 10, a photosensitive resin layer 20, a resin protective layer 30, and a base film 40.

Although not shown in the drawing, each of the cover film 10 and/or the base film 40 may have a release layer on at least one surface thereof.

FIG. 2 illustrates the cross-section of the layer structure of a display substrate including the film type photosensitive transfer material according to the present invention, upon an exposure process. In this way, when the film type photosensitive transfer material according to the present invention is applied to a display substrate, for example, a printed wiring board, a PCB and the like, the cover film 10 is removed from the film type photosensitive transfer material, the film type photosensitive transfer material is laminated on a FCCL 50 such that the photosensitive resin layer of the transfer material and the FCCL face each other, the base film 40 is removed, and then a mask is placed on the resin protective layer, after which an exposure process and a development process are performed. Below, individual layers are described in detail. <Base Film>

The base film of the present invention functions as a support of the resin protective layer and the photosensitive resin layer and thus should have adequate mechanical properties. Examples of material for the base film include polyester including polyethyleneterephthalate, polyethylenenaphthalate and so on, polyethylene, polypropylene, polyimide, polyamide, cellulose triacetate, cellulose diacetate, alkyl poly (meth) acrylate, (meth) acrylic acid ester copolymer, copolymer of polyvinyl chloride and vinyl acetate, polytetrafluoroethylene, and

polytrifluoroethylene. Particularly useful is polyethyleneterephthalate. The thickness of the base film is set to 10-100 μm and preferably 15-30 μm, but is not limited thereto. Depending on the composition of the resin protective layer which will be described later, the base film may have a release layer for controlling releasability. As such, particular limitations are not imposed on the forming process and composition of the release layer, as long as the release layer satisfies surface properties able to prevent damage to the resin protective layer while exhibiting adhesion between the base film and the resin protective layer greater than adhesion between the cover film and the photosensitive resin layer. <Resin Protective Layer>

The resin protective layer is disposed between the base film and the photosensitive resin layer. The film type photosensitive transfer material according to the embodiment of the present invention including such a resin protective layer may be subjected to an exposure process after the base film has been removed and a mask has been then placed on the resin protective layer.

Thus, the resin protective layer should be easily detached from the base film and should not adhere with the mask. Also, the resin protective layer is required to have low adhesion to the extent that defects do not occur even

when resin protective layers are stacked or the FCCL and the resin protective layer come into contact with each other in a sheet processing process or a roll-to-roll process after the exposure process. In particular, when an exposure process is conducted in a state in which the resin protective layer is exposed due to the removal of the base film, it is important that the resin protective layer not adhere with the mask. Examples of the mask include polyethyleneterephthalate (PET) , glass, etc. Accordingly, a PET film is laminated on the resin protective layer of the present invention exposed due to removal of the base film and then must also be easily separated therefrom.

From this point of view, the resin protective layer of the present invention may have adhesion of 0.005 kgf/cuf or less, the adhesion being defined as the force per unit area required to separate an additional PET film, which has been laminated on the resin protective layer exposed due to the removal of the base film, from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film. Specifically, the adhesion is determined in a manner such that a cover film is removed from a film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm, the transfer material sample is laminated on a FCCL at a rate of 2 m/min under conditions of 110 ^° C and 4 kgf/cilf, and then a base film is removed, after which a PET film having a width of 4 cm, a length of 25 cm and

a thickness of 19 (M is laminated on the layer exposed due to the removal of the base film at a rate of 2 m/min under conditions of 110 °C and 4 kgf/cnf and then the force per unit area required to separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film is measured using a universal testing machine (UTM) .

In the case where the resin protective layer has adhesion greater than 0.005 kgf/cin ² , the mask which is applied on the resin protective layer is not easy to remove again therefrom and thus the surface of the resin protective layer may be damaged, making it difficult to obtain favorable effects by the exposure process after removal of the base film. Also, the resin protective layer should block introduction of oxygen which impedes the polymerization of the photosensitive resin layer in the exposure process, and further, should be eliminated in the development process after the exposure process. Thus, the resin protective layer may be an alkali developable polymer layer. As such, the term "alkali developable polymer" indicates that a polymer is developed by a diluted alkali solution, for example, Na2CO3, NaOH or KOH.

So, the resin protective layer may be prepared from a composition including a water-soluble polymer selected from among water-soluble salts of polyvinylether maleic anhydride,

water-soluble salts of cellulose ether, water-soluble salts of carboxyalkyl cellulose, water-soluble salts of carboxyalkyl starch, polyvinylalcohol, polyvinylpyrrolidone, various types of polyacrylamide, water-soluble salts of polyamide, water-soluble salts of polyacrylic acid, polyethyleneglycol, polypropyleneglycol, gelatin, poly (ethyleneoxide) , and starch.

Because the viscosity of the composition for forming the resin protective layer has an influence on the properties of a coating layer and is affected by the degree of polymerization of the polymer, a weight average molecular weight of the polymer of the composition may range from 5,000 to 300,000. If the weight average molecular weight is less than 5000, it is difficult to apply the composition in the form of a film and a function of protecting the photosensitive resin layer becomes deteriorated due to low strength. Conversely, if the weight average molecular weight exceeds 300,000, a development time is increased and there is worry about damage to the resin protective layer upon removal of the base film after the lamination on the FCCL.

In the film type photosensitive transfer material according to a preferred embodiment of the present invention, the resin protective layer may have solubility of 5 g or less in methylethylketone (MEK) at 25 ^° C in order to prevent the component diffusion between the photosensitive resin layer and the resin protective layer during distribution of

products and to prolong the shelf life of products.

The solubility in MEK is defined as a decrement in the weight of the resin protective layer resulting from adding 50 g of a resin protective layer to 100 g of MEK, performing stirring at 25 ^° C for 1 hour and then filtration using filter paper, and measuring the weight of the resin protective layer remaining on the filter paper.

In the case of the film type photosensitive transfer material according to the embodiment of the present invention, the exposure process may be performed after removal of the base film in a post process. In this case, when a predetermined period of time is required to perform the exposure process, the properties of the resin protective layer exposed to the external environment may change due to moisture absorption. Hence, in the film type photosensitive transfer material according to the preferred embodiment of the present invention, the resin protective layer may have an adhesion change of 5000% or less as represented by Equation 1 below. Equation 1

. „ _,, .. .. Second Adhesion - First Adhesion

Adhesion Change (%) = x 100

First Adhesion wherein the first adhesion is defined as the force per unit area required to separate an additional PET film, which has been laminated on the resin protective layer shortly after removal of the base film, from a position of 5 cm to a position of 8 cm distant from the release starting point of

the PET film, and the second adhesion is defined as the force per unit area required to separate an additional PET film, which has been laminated on the resin protective layer, from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film, the resin protective layer being prepared by removing the base film therefrom and allowing the resin protective layer to stand for 10 days under conditions of temperature of 25 ^° C and humidity of 50%.

Accordingly, the resin protective layer may be a polyvinylalcohol-based resin layer. The polyvinylalcohol- based resin layer will be understood as a resin layer including at least 10 wt% of polyvinylalcohol resin.

In the case where the resin protective layer is a polyvinylalcohol-based resin layer, applicability may vary depending on the type of base film. Hence, a wetting agent may be further included.

Upon selection of the base film and the cover film which will be described later, there is a case requiring control of releasability. In this case, an additive for controlling releasability, for example, a wetting agent, a leveling agent, an antifoaming agent, a binder, and an adhesive agent, may be used.

The additive is not particularly limited, and any additive may be used as long as the adhesion between the cover film and the photosensitive resin layer may be adjusted to be smaller than the adhesion between the base film and the

resin protective layer.

The process of forming the resin protective layer is not particularly limited, and includes dissolving the composition for forming the resin protective layer in an organic solvent or water and preferably water, thus preparing a composition solution, applying the composition solution on the base film, and then drying it.

The exposure process is performed in a state in which the resin protective layer is formed, and thus, in order to increase the resolution, it is preferred that the resin protective layer be thinner. The thickness of the resin protective layer may be set to 0.001-10 μm.

<Photosensitive Resin Layer>

A composition for the photosensitive resin layer includes a binder polymer, a photopolymerizable monomer, a photoinitiator, and other additives, and may vary depending on the properties and nature of PCBs.

The process of forming the photosensitive resin layer which is disposed to be in contact with the above resin protective layer is not particularly limited and includes applying the photosensitive resin layer on the cover film and then attaching it to the resin protective layer formed on the base film.

The thickness of the photosensitive resin layer may be set to 10-100 μm depending on the type of PCBs.

<Cover Film>

The cover film should have releasability adequate for easily separating it upon application of the film type transfer material to a post process and for preventing the separation thereof upon storage and distribution. The photosensitive resin layer is applied on the cover film and is then laminated on the resin protective layer formed on the base film, thus manufacturing a film type photosensitive transfer material. As such, in consideration of the applicability of the photosensitive resin layer, the cover film may be a polyester film. Taking into consideration releasability, particularly useful is a polyester film having a release layer. An example of the process of forming the release layer includes but is not limited to coating or printing of silicone. The release layer is not particularly limited in terms of the forming process and composition, as long as the adhesion between the cover film and the photosensitive resin layer is smaller than that between the base film and the resin protective layer and the surface properties of the photosensitive resin layer are not degraded.

In the case where forming the resin protective layer on the base film, applying the photosensitive resin layer on the resin protective layer, and laminating the cover film are conducted, a polyolefin film 15-25 μm thick may be used as the cover film.

[Mode for Invention]

A better understanding of the present invention may be obtained through the following examples, which are set forth to illustrate, but are not to be construed as the limit of the present invention. <Example 1>

(a) Methacrylic acid, acrylic acid and methyl methacrylate (MAA) were polymerized at a weight ratio of 20:10:70 under conditions of a MEK solvent, a 1% AIBN polymerization initiator, a reaction temperature of 80 ^° C, a reaction time of 4 hours and a 3% AIBN post initiator, thus preparing an acrylic acid polymer (weight average MW: 70,000, solid content: 50%).

(b) The acrylic acid polymer was diluted to 200 cps with MEK, thus obtaining a composition for a resin protective layer, after which the composition thus obtained was applied on a base film (OPP) 20 μm thick using a coating bar and then dried in a convection oven at 80 ^° C for 10 min, thus forming a resin protective layer 2 μm thick. (c) A photosensitive resin composition was formed with components and amounts used in UH-9200 series (available from Kolon) . Specifically, a photoinitiator was dissolved in MEK and methyl alcohol solvents, mixed with a photopolymerizable oligomer and a binder polymer and then stirred for 1 hour using a mechanical stirrer, thus preparing a photosensitive resin composition.

(d) The photosensitive resin composition was applied on a cover film (OPP) 20 μm thick using a coating bar and then dried in a convection oven at 80 ^° C for 6 min, thus forming a photosensitive resin layer 15 μm thick. (e) After completion of the drying process, the photosensitive resin layer of (d) was laminated on the resin protective layer of (b) to be in contact with each other at 50 ^° C under pressure of 4 kgf/cuf, thus completing a film type photosensitive transfer material having a thickness of 57 μna. as illustrated in FIG. 1.

<Example 2>

A film type photosensitive transfer material having a thickness of 57 μm was manufactured in the same manner as in Example 1, with the exception that polyethyleneglycol (weight average MW: 20,000, available from Sigma-Aldrich) diluted to 200 cps with secondary distilled water was used as the composition for a resin protective layer.

<Example 3>

A film type photosensitive transfer material having a thickness of 55.5 μm was manufactured in the same manner as in Example 1, with the exception that the composition for a resin protective layer was applied to a thickness of 0.5 jMii.

<Example 4>

A film type photosensitive transfer material having a thickness of 56 μm was manufactured in the same manner as in Example 1, with the exception that a PET film having a silicone release layer (thickness: 19 μm, CY201-19 μm, available from Kolon) was used as the cover film, in lieu of OPP.

<Comparative Example 1>

A photosensitive resin composition was prepared with components and amounts used for UH-9200 series (available from Kolon) , applied on a PET film 19 μm thick (FDFR, available from Kolon) using a coating bar, and then dried in a convection oven at 80 ^° C for 6 min, thus forming a photosensitive resin layer 15 μm thick. Then, the dried film was laminated on a polyester film (23 μm) at 25 ^° C under pressure of 4 kgf/cirf, thus manufacturing a film type photosensitive transfer material having a thickness of 57 μm.

The releasability, adhesion and adhesion change of the film type photosensitive transfer materials manufactured in the above examples and comparative example were measured through the following procedures. The results are shown in

Table 1 below.

(1) Releasability <Cover Film>

The force per unit area required to separate the cover

film of the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm from a position of 5 cm to a position of 8 cm distant from the release starting point of the cover film was measured using a UTM (4303 series, available from Instron) .

<Base Film>

The cover film was removed from the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm, after which the transfer material sample was laminated on a CCL at a rate of 2 m/min at 110 ^" C under pressure of 4 kgf/αif. Thereafter, the force per unit area required to separate the base film from a position of 5 cm to a position of 8 cm distant from the release starting point of the base film was measured using a UTM (4303 series, available from Instron) . (2) Adhesion

The cover film was removed from the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm, the transfer material sample was laminated on a CCL at a rate of 2 m/min under conditions of 110 ^° C and 4 kgf/cnf, and then the base film was removed. Subsequently, a PET film (FDFR, available from Kolon) having a width of 4 cm, a length of 25 cm and a thickness of 19 μm was laminated on the layer exposed due to removal of the base film at a rate of 2 m/min under conditions of 110 ^° C and 4 kgf/cnf, after which the force per unit area required to

separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film was measured using a UTM (4303 series, available from Instron) . As such, the PET film was laminated under the same conditions as those for attaching a mask in a typical exposure process. The adhesion thus measured corresponds to the adhesion between the resin protective layer and the PET film in the examples and Comparative Example 2 and to the adhesion between the photosensitive resin layer and the PET film in Comparative Example 1.

(3) Adhesion Change of Resin Protective Layer The first adhesion and the second adhesion of the film type photosensitive transfer material of Examples 1 to 4 were determined as follows, and the adhesion change was calculated as represented by Equation 1 below. Equation 1

, „ . _^7 .. .. Second Adhesion - First Adhesion . _ _

Adhesion Change (%) = x 100

First Adhesion

The cover film was removed from the film type photosensitive transfer material sample having a width of 3 cm and a length of 20, the transfer material sample was laminated on a CCL at a rate of 2 m/min under conditions of

110 ^° C and 4 kgf/cnf, and then the base film was removed.

Shortly after removal of the base film, a PET film (FDFR, available from Kolon) having a width of 4 cm, a length of 25 cm and a thickness of 19 μm was laminated on the layer exposed

due to removal of the base film at a rate of 2 m/min under conditions of 110 ^° C and 4 kgf/cirf, and then the force per unit area required to separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film was measured using a UTM (4303 series, available from Instron) . The adhesion thus measured was defined as the first adhesion.

Also, in the same manner, the base film was removed from the transfer material sample, the transfer material sample was allowed to stand for 240 hours under conditions of temperature of 25 ^° C and humidity of 50%, an additional PET film was laminated on the resin protective layer of the transfer material sample through the process as above, and then the force per unit area required to separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film was measured using a UTM (4303 series, available from Instron) . The adhesion thus measured was defined as the second adhesion.

TABLE 1

As is apparent from the above results, the adhesion between the photosensitive resin layer and the cover film and

the adhesion between the resin protective layer and the base film could be seen to fall within a range of not degrading workability. In the examples, the adhesion could be seen to be much lower than in the comparative example. Thereby, the adhesion between the resin protective layer of the examples and the mask material typically used under exposure conditions is very low, and therefore the transfer material of the present invention can be easily handled in the exposure process. In addition, the film type photosensitive transfer material of the above examples and comparative example was applied on a PCB through the following procedures, and the properties thereof were measured.

A surface of a CCL was pre-treated with a brush, thus forming a new copper surface having an appropriate roughness, after which the CCL was acid-treated with 5% sulfuric acid solution, washed with water, dried, and then loaded into a laminator. As such, used as the laminator was Hakuto Mach 61Oi. The film type photosensitive transfer material of the examples and comparative example was laminated on the CCL at a rate of 2 m/min at 110 ^° C under pressure of 4kgf/citf. In this case, pre-heating was not conducted. Thereafter, an exposure process was conducted using a UV light source (Perkin Elmer OB-7120, 5 Kw collimated light) . After completion of the exposure process, the PCB was passed through a developing machine, thus developing it.

In Examples 1 to 4 in which the resin protective layer was formed, the base film was peeled off before the exposure process. In Comparative Example 1 in which the resin protective layer was not formed, the base film was peeled off after the exposure process before the development process.

(4) Sensitivity and Exposure Dose

In the exposure process, a Stouffer 21-step tablet was placed on the resin protective layer in Examples 1 to 4 and on the base film in Comparative Example 1, after which the exposure dose for obtaining 5-step, 6-step and 7-step sensitivity was measured using a light irradiance meter (UV- 351, available from ORC) . The results are shown in Table 2 below. As such, the sensitivity was evaluated by the highest step number of the photoresist remaining on the substrate after the development process.

(5) Development Time

The period of time required to completely wash out the lamination portion of the PCB, which had been laminated on the CCL, by a developer through a developing machine was determined to be a minimum development time. The actual development time was estimated by doubling the minimum development time. In the case where the resin protective layer was present, the actual development time was calculated by adding the time required to develop the resin protective layer to the minimum development time.

(6) Circuit Properties: Resolution, Fine Line Adhesion,

1/1 (Line/Space) Resolution

Using Kolon Test Artwork, the resolution, the fine line adhesion, the 1/1 (line/space) resolution were measured, thus evaluating the circuit properties. The resolution was determined by measuring the minimum spacewidth of the circuit pattern resulting from developing the unexposed portion of the substrate. As the spacewidth thus measured was smaller, the resolution was evaluated to be superior. The mask used for the measurement of the resolution was formed with a pattern at intervals of 0.5 μm to 4-20 μm. A desired resolution was determined using a mask having a pattern at intervals of 400 μm. Further, the fine line adhesion was determined by measuring the minimum spacewidth of the linear circuit pattern without corrosion resulting from developing the exposed portion of the substrate. As the spacewidth thus measured was smaller, the fine line adhesion was evaluated to be superior. The mask used for the measurement of the fine line adhesion was formed with a pattern at intervals of 0.5 μm to 4-20 μm. A desired fine line adhesion was determined using a mask having a pattern at intervals of 400 μm. Furthermore, the 1/1 resolution was determined by measuring the minimum spacewidth cleanly developed under conditions in which the intervals between two adjacent circuit lines were set to 1:1. (7) Surface Analysis

The PCB to which the film type photosensitive transfer

material of Example 1 and Comparative Example 1 was applied was exposed and developed as above, after which the surface thereof was observed using an electron microscope. The results are shown in FIGS. 4 and 5.

TABLE 2

As is apparent from the above results, there was little difference in the exposure dose required to realize the same step number between the examples and the comparative example. As the results of measurement of the circuit properties, the properties including the resolution were exhibited to be superior in the examples . In the case of the film type photosensitive transfer material including the resin protective layer according to the present invention, the development time of the resin protective layer was about 0.5-3 sec per 1 βm thickness of the resin protective layer.

As is apparent from surface observation through electron microscope images of FIGS. 4 and 5, in FIG. 4 showing the surface image of the PCB to which the film type photosensitive transfer material of Example 1 was applied, the roughness of the side and surface was seen to be smaller despite higher magnification compared to FIG. 5 using the transfer material of Comparative Example 1. Thus, in the case where the film type photosensitive transfer material according to the present invention is applied, handling in the exposure process becomes easy and the resolution can be improved.

<Example 5>

(a) 20 g of PVA205 (available from Kuraray, Japan) was added to 100 g of distilled water and then stirred at 80 ^° C for 6 hours to completely dissolve it, thus obtaining a composition for a resin protective layer, after which the composition thus obtained was applied on a base film 19 μm thick (PET film having silicone release layer, CY201-19 μm, available from Kolon) using a coating bar, and then dried in a convection oven at 80 ^" C for 10 min, thus forming a resin protective layer having 2 μm thick.

(c) A photosensitive resin composition was prepared with components and amounts used for UH-9200 series (available from Kolon) . Specifically, a photoinitiator was dissolved in MEK and methyl alcohol solvents, mixed with a

photopolymerizable oligomer and a binder polymer and then stirred for 1 hour using a mechanical stirrer, thus preparing a photosensitive resin composition.

(d) The photosensitive resin composition was applied on a cover film 19 μm thick (PET film having silicone release layer, CY201-19 μm, available from Kolon) using a coating bar, and then dried in a convection oven at 80 ^° C for 6 min, thus forming a photosensitive resin layer 15 μm thick.

(e) After completion of the drying process, the photosensitive resin layer of (d) was laminated on the resin protective layer of (b) to be in contact with each other at 50 ^° C under pressure of 4 kgf/cin ² , thus completing a film type photosensitive transfer material having a thickness of 55 μm as illustrated in FIG. 1.

<Example 6>

(a) 20 g of PVA205 (available from Kuraray, Japan) and 0.5 g of BYK-349 (wetting agent, available from BYK Chemie) were added to 100 g of distilled water and then stirred at 80 ^° C for 6 hours to completely dissolve, thus obtaining a composition for a resin protective layer, after which the composition thus obtained was applied on a base film 19 μm (PET film, FDFR-19, available from Kolon) using a coating bar, and then dried in a convection oven at 80 ^° C for 10 min, thus forming a resin protective layer 2 μm thick.

(c) A photosensitive resin composition was prepared

with components and amounts used for UH-9200 series

(available from Kolon) . Specifically, a photoinitiator was dissolved in MEK and methyl alcohol solvents, mixed with a photopolymerizable oligomer and a binder polymer and then stirred for 1 hour using a mechanical stirrer, thus preparing a photosensitive resin composition.

(d) The photosensitive resin composition was applied on a cover film 19 μm thick (PET film having silicone release layer, CY201-19 jM, available from Kolon) using a coating bar, and then dried in a convection oven at 80 ^° C for 6 min, thus forming a photosensitive resin layer 15 [M thick.

(e) After completion of the drying process, the photosensitive resin layer of (d) was laminated on the resin protective layer of (b) to be in contact with each other at 50 ^° C under pressure of 4 kgf/cin ² , thus completing a film type photosensitive transfer material having a thickness of 55 βm as illustrated in FIG. 1.

<Example 7> (a) 20 g of PVA205 (available from Kuraray, Japan) was added to 100 g of distilled water and then stirred at 80 ^° C for 6 hours to completely dissolve, thus obtaining a composition for a resin protective layer, which was then applied on a base film 19 μm thick (PET film having silicone release layer, CY201-19 μm, available from Kolon) using a coating bar and dried in a convection oven at 80 ^" C for 10 min,

thus forming a resin protective layer 10 μm thick.

(c) A photosensitive resin composition was prepared with components and amounts used for UH-9200 series

(available from Kolon) . Specifically, a photoinitiator was dissolved in MEK and methyl alcohol solvents, mixed with a photopolymerizable oligomer and a binder polymer, and then stirred for 1 hour using a mechanical stirrer, thus preparing a photosensitive resin composition.

(d) The photosensitive resin composition was applied on a cover film 19 μm thick (PET film having silicone release layer, CY201-19 μm, available from Kolon) using a coating bar, and then dried in a convection oven at 80°C for 6 min, thus forming a photosensitive resin layer 15 μm thick.

(e) After completion of the drying process, the photosensitive resin layer of (d) was laminated on the resin protective layer of (b) to be in contact with each other at 50 ^° C under pressure of 4 kgf/cuf, thus completing a film type photosensitive transfer material having a thickness of 63 μm as illustrated in FIG. 1.

The releasability, and the adhesion, MEK solubility and adhesion change of the resin protective layer, of the film type photosensitive transfer material of Examples 5 to 7 were measured through the following procedures. The results are shown in Table 3 below. (1) Releasability

<Cover Film>

The force per unit area required to separate the cover film of the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm from a position of 5 cm to a position of 8 cm distant from the release starting point of the cover film was measured using a UTM (4303 series, available from Instron) .

<Base Film>

The cover film was removed from the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm, after which the transfer material sample was laminated on a CCL at a rate of 2 m/min at 110 ^" C under pressure of 4 kgf/αif. Thereafter, the force per unit area required to separate the base film from a position of 5 cm to a position of 8 cm distant from the release starting point of the base film was measured using a UTM (4303 series, available from Instron) .

(2) Adhesion

The cover film was removed from the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm, the transfer material sample was laminated on a CCL at a rate of 2 m/min under conditions of

110 ^° C and 4 kgf/cm ² , and then the base film was removed.

Subsequently, a PET film (FDFR, available from Kolon) having a width of 4 cm, a length of 25 cm and a thickness of 19 μm was laminated on the layer exposed due to removal of the base

film at a rate of 2 m/min under conditions of 110 ^° C and 4 kgf/cuf, after which the force per unit area required to separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film was measured using a UTM (4303 series, available from Instron) .

As such, the PET film was laminated under the same conditions as those for attaching a mask in a typical exposure process. The adhesion thus measured corresponds to the adhesion between the resin protective layer and the PET film.

(3) Adhesion Change of Resin Protective Layer The first adhesion and the second adhesion of the film type photosensitive transfer material of Examples 5 to 7 were determined as follows, and the adhesion change was calculated using Equation 1 below. Equation 1

. .. . _ ₇ .. .. Second Adhesion - First Adhesion _{1 λλ}

Adhesion Change (%) = x 100

First Adhesion

The cover film was removed from the film type photosensitive transfer material sample having a width of 3 cm and a length of 20 cm, the transfer material sample was laminated on a CCL at a rate of 2 m/min under conditions of

110 ^° C and 4 kgf/cnf, and then the base film was removed.

Shortly after removal of the base film, a PET film (FDFR, available from Kolon) having a width of 4 cm, a length of 25 cm and a thickness of 19 [M was laminated on the layer exposed

due to removal of the base film at a rate of 2 m/min under conditions of 110 ^° C and 4 kgf/αif, after which the force per unit area required to separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film was measured using a UTM (4303 series, available from Instron) . The adhesion thus measured was defined as the first adhesion.

Also, in the same manner, the base film was removed from the transfer material sample, the transfer material sample was allowed to stand for 240 hours under conditions of temperature of 25 ^° C and humidity of 50%, an additional PET film was laminated on the resin protective layer of the transfer material sample through the process as above, and then the force per unit area required to separate the PET film from a position of 5 cm to a position of 8 cm distant from the release starting point of the PET film was measured using a UTM (4303 series, available from Instron) . The adhesion thus measured was defined as the second adhesion. (4) Solubility of Resin protective layer in MEK The solubility of the resin protective layer in MEK was determined by adding 50 g of the resin protective layer to 100 g of MEK, performing stirring at 25 ^° C for 1 hour and then filtration using filter paper, and measuring the weight of the resin protective layer remaining on the filter paper. The solubility was defined as a decrement in the weight of the resin protective layer.

TABLE 3

As is apparent from the above results, the adhesion between the photosensitive resin layer and the cover film and the adhesion between the resin protective layer and the base film could be seen to fall within a range of not degrading workability. The resin protective layer could be seen to have low adhesion with the PET film used as the mask. Thereby, the adhesion between the resin protective layer of the examples and the mask material typically used under exposure conditions is very low and thus the transfer material according to the present invention can be easily handled upon the exposure process.

Further, the resin protective layer had low solubility of 5 g or less in MEK. In order to prevent the component diffusion between the photosensitive resin layer and the resin protective layer in the storage and distribution of the film type photosensitive transfer material for a long period of time, particularly useful as the resin protective layer is a polyvinylalcohol resin layer.

Furthermore, the resin protective layer had a low adhesion change of 5000% or less. Even after a lapse of a

predetermined period of time following removal of the base film in a post process using the film type photosensitive transfer material, problems in which the resin protective layer adheres with the mask attributable to moisture absorption can be prevented.

In addition, the film type photosensitive transfer material of the above examples and comparative example was applied on a PCB through the following procedures, and the properties thereof were measured. The results are shown in Table 4 below.

A surface of a CCL was pre-treated with a brush, thus forming a new copper surface having an appropriate roughness, after which the CCL was acid-treated with 5% sulfuric acid solution, washed with water, dried, and then loaded into a laminator. As such, the laminator was Hakuto Mach 61Oi. The film type photosensitive transfer material of the examples and comparative example was laminated on the CCL at a rate of 2 m/min at 110 ^° C under pressure of 4 kgf/cnf. In this case, pre-heating was not conducted. Thereafter, an exposure process was conducted using a UV light source (Perkin Elmer OB-7120, 5 Kw collimated light) . After completion of the exposure process, the PCB was passed through a developing machine, thus developing it.

As such, the base film was peeled off before the exposure process.

(5) Sensitivity and Exposure Dose

In the exposure process, a Stouffer 21-step tablet was placed on the resin protective layer, after which the exposure dose for obtaining 5-step, 6-step and 7-step sensitivity was measured using a light irradiance meter (UV- 351, available from ORC) . The results are shown in Table 1. The sensitivity was evaluated by the highest step number of the photoresist remaining on the substrate after the development process.

(6) Development Time The period of time required to completely wash out the lamination portion of the PCB, which had been laminated on the CCL, by a developer through a developing machine was determined to be a minimum development time. The actual development time was estimated by doubling the minimum development time. In the case where the resin protective layer was present, the actual development time was calculated by adding the time required to develop the resin protective layer to the minimum development time.

(7) Circuit Properties: Resolution, Fine Line Adhesion, 1/1 (Line/Space) Resolution

Using Kolon Test Artwork, the resolution, the fine line adhesion, the 1/1 (line/space) resolution were measured, thus evaluating the circuit properties.

The resolution was determined by measuring the minimum spacewidth of the circuit pattern resulting from developing the unexposed portion of the substrate. As the spacewidth

thus measured was smaller, the resolution was evaluated to be superior. The mask used for the measurement of the resolution was formed with a pattern at intervals of 0.5 μm to 4-20 μm. A desired resolution was determined using a mask having a pattern at intervals of 400 μm. Further, the fine line adhesion was determined by measuring the minimum spacewidth of the linear circuit pattern without corrosion resulting from developing the exposed portion of the substrate. As the spacewidth thus measured was smaller, the fine line adhesion was evaluated to be superior. The mask used for the measurement of the fine line adhesion was formed with a pattern at intervals of 0.5 μm to 4-20 μm. A desired fine line adhesion was determined using a mask having a pattern at intervals of 400 μm. Furthermore, the 1/1 resolution was determined by measuring the minimum spacewidth cleanly developed under conditions in which the intervals between two adjacent circuit lines were set to 1:1. (8) Surface Analysis The PCB to which the film type photosensitive transfer material of Examples 5 to 7 was applied was exposed and developed as above, after which the surface thereof was observed using an electron microscope. The results are shown in FIGS. 6 to 8.

TABLE 4

As is apparent from the above results, there was little difference in the exposure dose required to realize the same step number between the examples and the comparative example. As the results of measurement of the circuit properties, the circuit properties including the resolution could be seen to be superior in the examples.

In the case of the film type photosensitive transfer material including the resin protective layer according to the present invention, the development time of the resin protective layer was about 0.5-3 sec per 1 μm thickness of the resin protective layer.

As is apparent from surface observation through electron microscope images of FIGS. 6 to 8, in FIGS. 6 to 8 showing the surface image of the PCB including the film type photosensitive transfer material of Examples 5 to 6, the roughness of the side and surface was seen to be smaller despite higher magnification compared to FIG. 5 using the transfer material of Comparative Example 1. Therefore, in the case where the film type photosensitive transfer material according to the present invention is applied, handling in the exposure process becomes easy and the resolution can be

improved .