KR20140084394A - Photosensitive Resin Composition and Dry Film Photoresist Formed Thereof - Google Patents

Abstract

The present invention relates to a photosensitive resin composition and a dry film photoresist manufactured therefrom and, more specifically, provides a photosensitive resin composition and a dry film photoresist manufactured therefrom, which have enhanced chemical resistance, thereby being stable for plating and etching processes; and can work as a resist for an alkali etching solution which is conventionally lack of tolerance, thereby facilitating manufacturing of various shaped boards which were impossible by conventional processes.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition and a dry film photoresist prepared therefrom,

The present invention relates to a photosensitive resin composition and a dry film photoresist prepared therefrom.

Generally, dry film photoresists are widely used for lamination on copper clad laminates. In this regard, an example of a manufacturing process of a printed circuit board (hereinafter referred to as a PCB) is a preprocessing process in order to laminate a copper clad laminate as a raw material of a PCB. The pretreatment process is in the order of drilling, deburring, and frontal in the outer layer process, and is faced or pickled in the inner layer process. Bristle brush and jet pumice processes are mainly used in the frontal process, and pickling can be carried out by soft etching and 5 wt% sulfuric acid pickling.

In order to form a circuit on the copper-clad laminate after the pretreatment, a dry film photoresist (hereinafter referred to as DFR) is usually laminated on the copper layer of the copper clad laminate. In this process, the photoresist layer of the DFR is laminated on the copper surface while removing the protective film of the DFR using a laminator. Generally, the lamination speed is 0.5 to 3.5 m / min, the temperature is 100 to 130 캜, and the roller pressure is 10 to 90 psi.

The laminated printed circuit board is exposed to the photoresist of the DFR using a photomask having a desired circuit pattern after being left for 15 minutes or more for stabilizing the substrate. When the ultraviolet rays are irradiated to the photomask in this process, the photoresist irradiated with ultraviolet light starts to be polymerized by the photoinitiator contained in the irradiated site. Initially, the oxygen in the photoresist is consumed, and the next activated monomer is polymerized to initiate a crosslinking reaction, and then a large amount of monomer is consumed and polymerization proceeds. On the other hand, the unexposed portion exists in a state in which the crosslinking reaction does not proceed.

Next, a developing process for removing the unexposed portion of the photoresist is carried out. In the case of the alkali developing DFR, 0.8 to 1.2 wt% of potassium carbonate and aqueous solution of sodium carbonate are used as the developing solution. In this process, the photoresist of the unexposed portion is washed away by the saponification reaction between the carboxylic acid of the binder polymer and the developer in the developer, and the cured photoresist remains on the copper surface.

The circuit is then formed through other processes depending on the inner and outer layer processes. In the inner layer process, a circuit is formed on the substrate through the etching and peeling process. In the outer layer process, the plating and the tentering process are performed, and etching and solder peeling are performed to form a predetermined circuit.

In general, the dry film photoresist exposed in the plating process is placed in a strong acid or strong alkaline solution environment. For this reason, when the chemical resistance is insufficient, the dry film photoresist is separated from the copper clad laminate.

The main object of the present invention is to provide a photosensitive resin composition having improved chemical resistance while exhibiting inherent physical properties such as fine line adhesion and resolution in a dry film photoresist, and a dry film photoresist prepared using the photosensitive resin composition.

In order to achieve the above object, one embodiment of the present invention relates to a photopolymerizable polyfunctional monomer; A photopolymerization initiator; Polymeric binders; And a copolymer of propylene acrylate and acrylic acid.

In one preferred embodiment of the present invention, the propargyl acrylate is a compound represented by the general formula (1).

≪ Formula 1 >

In a preferred embodiment of the present invention, the copolymer of propylene acrylate and acrylic acid may have a weight average molecular weight of 10,000 to 150,000 g / mol.

In a preferred embodiment of the present invention, the copolymer of propylene acrylate and acrylic acid is 5 to 40% by weight based on the solid content of the photosensitive resin composition.

Another embodiment of the present invention provides a dry film photoresist comprising a photoresist layer formed from a photosensitive resin composition.

The photosensitive resin composition according to the present invention and the dry film photoresist produced therefrom have excellent chemical resistance and can be used as a resist in an alkaline etching solution which is stable in plating, It is possible to make various types of boards which can not be manufactured easily.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The present invention, in one aspect, relates to a photopolymerizable polyfunctional monomer; A photopolymerization initiator; Polymeric binders; And a copolymer of propylene acrylate and acrylic acid.

Hereinafter, the present invention will be described in more detail.

(1) Copolymer of propylene acrylate and acrylic acid

The copolymer of propylene acrylate and acrylic acid contained in the photosensitive resin composition of the present invention is obtained by reacting propylene acrylate and acrylic acid in an organic solvent at 60 to 100 ° C for 4 to 8 hours. At this time, the prophylactic acrylate has an unsaturated group capable of photopolymerization at the time of exposure to increase the photochemical resistance by increasing the photocrosslinking density after exposure, and it may be a compound represented by the general formula (1).

≪ Formula 1 >

In the copolymer of propylene acrylate and acrylic acid, the weight ratio of propylene acrylate to acrylic acid is preferably 1: 0.1 to 1: 2. If the weight ratio of propylene acrylate is less than 0.1 weight part of acrylic acid, the effect of photopolymerization is insignificant and if the weight ratio of propylene acrylate is more than 2 weight parts, peeling property is lowered .

The copolymer of propylene acrylate and acrylic acid has the effect of improving the chemical resistance of the cured product than a general polymer conjugate by structurally having a photosensitive unsaturated group and an alkali developing acid at the same time.

The copolymer of propylene acrylate and acrylic acid preferably has a weight average molecular weight of 10,000 to 150,000 g / mol. When the weight average molecular weight is within the above range, it can have an excellent chemical resistance.

The copolymer of propylene acrylate and acrylic acid is preferably contained in an amount of 5 to 40% by weight based on the solid content of the photosensitive resin composition. If the content of the copolymer of propylene acrylate and acrylic acid is less than 5% by weight based on the solid content of the photosensitive resin composition, the effect on the addition of propylene acrylate and acrylic acid is insignificant. If the content is less than 40% by weight, Can be lowered.

(2) Photopolymerizable polyfunctional monomer

The photopolymerizable polyfunctional monomer of the present invention preferably has at least two terminal ethylene groups, and examples thereof include 1,6-hexanediol (meth) acrylate, 1,4-cyclohexanediol- (meth) (Meth) acrylate, 2-di- (p-hydroxyphenyl) -propane-, diethylene-, diethylene-, Di (meth) acrylate, glycerol tri (meth) acrylate, trimethylol propane tri- (meth) acrylate, 2,2'-bis- [4- (methacryloxy-polyethoxy) , Poly (propylene) di (meth) acrylate containing a bisphenol A group, and polyfunctional (meth) acrylate containing a urethane group, and the like.

The content of the photopolymerizable polyfunctional monomer is preferably 20 to 60% by weight based on the solids content of the entire photosensitive resin composition in view of fine line adhesion and resolution.

(3) Photopolymerization initiator

In the photosensitive resin composition of the present invention, the photopolymerization initiator is a substance that initiates a chain reaction with a photopolymerizable oligomer by UV and other radiation. Examples of the photopolymerization initiator include anthraquinone derivatives such as 2-methyl anthraquinone, Benzoin derivatives such as benzoin methyl ether, benzophenone, phenanthrenequinone, and 4,4 'bis- (dimethylamino) benzophenone.

In addition to these, there may be mentioned 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-methyl- 1- [4- (methylthio) 1-one, 2-benzyl-2-dimethylamino-1- [4-morpholinophenyl] butan- 2-methylpropan-1-one, 2,4-diethyl (2-hydroxyethyl) 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 3,3-dimethyl-4-methoxybenzophenone, benzophenone, 1-chloro-4- (4-isopropylphenyl) 2-hydroxy-2-methylpropan-1-one, 1- Dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, butyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2-isoamyl 4-dimethylaminobenzoate, 2,2-diethoxyacetophenone, benzylketone dimethyl acetal, benzyl ketone? -Methoxydiethyl acetal, 1-phenyl-1,2-propyldioxime-o methyl o-benzoyl benzoate, bis [4-dimethylaminophenyl) ketone, 4,4'-bis (diethylamino) benzophenone, 4,4'- Benzoin, methoxybenzoin, ethoxybenzoin, isopropoxybenzoin, n-butoxybenzoin, isobutoxybenzoin, tert-butoxybenzoin, p-dimethylaminoacetophenone , p-tert-butyltrichloroacetophenone, p-tert-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, dibenzosuberone, 4-phenoxyacetophenone, and pentyl 4-dimethylaminobenzoate.

The content of the photopolymerization initiator is usually preferably 2 to 10% by weight based on the solid content of the entire photosensitive resin composition. If the content of the photopolymerization initiator is less than 2% by weight, the photopolymerization initiator may fail to be crosslinked properly. If the amount of the photopolymerization initiator is more than 10% by weight, Or more.

(4) Polymer Binder

In the photosensitive resin composition of the present invention, the polymer binder is an alkali-soluble polymer resin as a copolymer of (meth) acrylic acid and (meth) acrylic acid ester. A copolymer of (meth) acrylic acid and (meth) acrylic acid ester can be obtained through copolymerization of two or more monomers selected from the following: methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate Acrylate, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, Methacrylamide, styrene, alpha -methyl styrene.

These copolymers preferably have a weight average molecular weight of 30,000 to 150,000 g / mol and a glass transition temperature of 50 to 150 DEG C in consideration of the coating property and followability of the dry film resist and the mechanical strength of the resist itself after formation of the circuit Do.

The content of the polymer binder is usually preferably 20 to 60% by weight based on the solid content of the entire photosensitive resin composition. If the polymer binder is added in an amount of less than 20% by weight, the adhesion of the film can be greatly increased. When the content of the polymer binder exceeds 60% by weight, May occur.

(5) Additives

The photosensitive resin composition of the present invention may contain a dye such as diamond green, a coloring agent such as tribromophenylsulfone, leuco crystal violet and the like depending on an optional purpose, and the content thereof is preferably 0.01 to 10% by weight of the solid content of the entire photosensitive resin composition Is usually preferred.

In addition, the photosensitive resin composition may contain a solvent by appropriately adjusting it according to a certain purpose. Examples of the solvent include methyl ethyl ketone, methanol, ethanol, acetone, and toluene.

In addition, the photosensitive resin composition makes it possible to distinguish exposure from unexposed light by changing the unoccluded light to green and the exposed part to blue by adding a dye.

In addition, the photosensitive resin composition may further include a heat stabilizer, an additive for long-term storage stability, and the like, if necessary.

In another aspect, the present invention relates to a dry film photoresist prepared using the photosensitive resin composition.

The dry film photoresist according to the present invention can be obtained by applying the above-described photosensitive resin composition to at least one surface of a base film to form a photosensitive layer (photoresist layer). At this time, the method of forming the photosensitive layer (photoresist layer) can be generally used without particular limitation, as long as the photosensitive layer can be formed using a resin composition.

The polymeric binder, the photopolymerizable polyfunctional monomer, the photopolymerization initiator, and the like described above are not intended to limit the present invention, and those skilled in the art will understand that various compounds Of course.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

< Manufacturing example  1>

A mechanical stirrer and a reflux condenser were attached to a four-neck round bottom flask, and 1.0 g of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was dissolved in 100 g of methyl ethyl ketone (MEK) as a solvent. 70 g of the propylene acrylate represented by the formula (1) and 30 g of acrylic acid were charged into a flask, respectively, and the temperature was raised to 80 DEG C, followed by polymerization for 4 hours to obtain a copolymer of propylene acrylate and acrylic acid having a weight average molecular weight of 35,000 g / .

< Example  1>

The copolymer of propargyl acrylate, acrylic acid, photopolymerizable polyfunctional monomer, photopolymerization initiator, polymer binder and additives obtained in Preparation Example 1 was conditioned in the composition as shown in Table 1, dried on a polyethylene terephthalate film, Mu m thickness and dried. After drying, a polyethylene film was laminated with a protective film to prepare a dry film photoresist. The content in Table 1 means the weight percentage contained in the solid content of the photosensitive resin composition.

ingredient Content (% by weight) Copolymer of propylene acrylate and acrylic acid The weight ratio of the propylene acrylate represented by the formula (1) to the methyl acrylate was 70:30 (solid content: 50% by weight) 10 Polymer binder Methyl methacrylate / styrene monomer copolymer (28/22/50 by weight, weight average molecular weight 60,000 g / mol, 50% by solid content) 35 Photopolymerization
Multifunctional monomer Polyethylene glycol dimethacrylate 10 Trimethylolpropane triacrylate 10 2,2'-bis- [4- (methacryloxy-polyethoxy) phenyl] propane 30 Photopolymerization initiator Benzophenone 2.2 4,4'-bis (diethylamino) benzophenone 2.0 additive Loico Crystal Violet 0.3 Diamond Green GH 0.5

The dry film photoresist prepared using the photosensitive resin composition prepared above was subjected to the following steps.

< Lamination >

The dry film photoresist was polished to a brush-polished copper-clad laminate having a thickness of 1.6 mm, a substrate preheating roll temperature of 120 캜, a laminator roll temperature of 115 캜, a roll pressure of 4.0 kgf / cm ² And laminated using a HAKUTO MACH 610i under a roll speed of 2.5 min / m.

<Phenomenon and resolution>

The dry film photoresist laminated on the copper-clad laminate was irradiated with ultraviolet rays at an exposure dose of 40 mJ using a Perkin-Elmer ( ^TM) OB7120 (parallel light exposing machine) using a circuit evaluation photomask, and left for 20 minutes. Thereafter, the development was carried out under the development conditions of spraying method with a 1.0 wt% aqueous solution of Na ₂ CO ₃ . The time taken until the dry film photoresist on the copper foil laminates was completely washed in the developing solution was measured using a stopwatch (minimum development time), and the product was fixed at a break point of 50% (minimum development time 2 ship).

< Example  2 to 5 and Comparative Example  1>

The photosensitive composition was prepared in the same manner as in Example 1 except for the content and molecular weight of the copolymer of propylene acrylate and acrylic acid and the content of the polymer binder, and then a dry film photoresist was prepared. Table 2 shows the compounds and contents used in Examples and Comparative Examples. The content in the following Table 2 means the weight percentage contained in the solid content of the photosensitive resin composition.

The weight average molecular weights of the following Table 2 were measured by the following methods.

&Lt; Weight average molecular weight &

Polystyrene was measured with a standard Waters 450 GPC. Columns were Shodex 10 ⁵ , 10 ⁴ and 10 ³ .

division The content of polymer binder
(weight%) Content (% by weight) of copolymer of 1,3,5-hexatriene monomer and acrylic acid The weight average molecular weight of a copolymer of 1,3,5-hexatriene monomer and acrylic acid
(g / mol) Example 1 38 10 30,000 Example 2 28 20 60,000 Example 3 34 14 100,000 Example 4 14 34 70,000 Example 5 24 24 120,000 Comparative Example 1 48 0 -

The properties of the dry film photoresist prepared using the photosensitive resin compositions prepared in Examples 1 to 5 and Comparative Example 1 were measured by the following methods, and the results are shown in Table 3 below.

&Lt; Fine wire adhesion (unit: 占 퐉)

After development, the ZEISS AXIOPHOT Microscope was used to measure the minimum line width at which the independent resist survives.

<Resolution (unit: 탆)>

The space between the circuit line and the circuit line was measured at 1: 1 and measured with a ZEISS AXIOPHOT Microscope.

<Tolerance of borohydric acid (unit: minute)>

The chemical resistance was evaluated by deeping the copper clad laminates which had been subjected to the development process to the borofluoric acid solution commonly used in the relevant industries. Boron hydrofluoric acid solution and taken out every 10 minutes to confirm whether or not the dry film photoresist adhered to the copper-clad laminate. That is, the time when the thin line having a line width of 100 mu m is attached is measured and measured. The method of confirming was that high-pressure air was sprayed on a line width of 100 mu m to visually confirm the detachment of the resist.

division Fine wire adhesion ^{* 1} Resolution ^{* 2} Borohydric acid resistance ^{* 3} Example 1 25 30 130 Example 2 25 28 180 Example 3 20 30 150 Example 4 35 40 250 Example 5 35 35 230 Comparative Example 1 25 28 90

^{* 1 The} fine line adhesion is the minimum line width in which the independent linewidth survives after development.

^{* 2} Resolution is the value measured 1: 1 between the circuit line and the circuit line.

^{* 3} Borophosphoric acid resistance: Time at which fine lines with a line width of 100 μm are attached.

As shown in Table 3, it can be seen that Examples 1 to 5 are remarkably superior in chemical resistance to borofluoric acid solution while maintaining the same fine line adhesion and resolution as Comparative Example 1.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (5)

Photopolymerizable polyfunctional monomer; A photopolymerization initiator; Polymeric binders; And a copolymer of propylene acrylate and acrylic acid.
The photosensitive resin composition according to claim 1, wherein the propylene acrylate is a compound represented by the following formula (1).
&Lt; Formula 1 >

The photosensitive resin composition according to claim 1, wherein the copolymer of propylene acrylate and acrylic acid has a weight average molecular weight of 10,000 to 150,000 g / mol.
The photosensitive resin composition according to claim 1, wherein the copolymer of propylene acrylate and acrylic acid is 5 to 40% by weight based on the solid content of the photosensitive resin composition.
A dry film photoresist comprising a photoresist layer formed from the photosensitive resin composition of any one of claims 1 to 4.