KR101052765B1 - Dry Film Photoresist - Google Patents

Abstract

The present invention provides a dry film photoresist having a structure in which a base film, a binder polymer, a photopolymerizable monomer, a photoinitiator and an additive, and a protective film are sequentially stacked, between the photosensitive resin composition layer and a protective film. The present invention provides a dry film photoresist in which a resin composition layer (a photosensitive resin composition layer including a polymerization inhibitor) is further laminated to the photosensitive resin composition layer composition. It is possible to suppress the scattering effect of the extra UV energy by the copper foil while controlling the sizing profile can be possible to implement a fine pattern circuit.

Description

Dry film photoresist             

1 is a cross-sectional view of a laminated structure of a dry film photoresist according to the present invention,

2 is a cross-sectional view of a laminated structure of a dry film photoresist disclosed in US Patent No. 5,300,401,

3 is a process chart of forming a dielectric layer using a dry film photoresist,

4 is a schematic diagram showing a phenomenon that the resolution of the dry film photoresist is reduced by the scattering effect during exposure,

5 is a view illustrating a form of a dry film photoresist that is subjected to a development process after removing a photomask and then peeling off a base film after the exposure process according to FIG. 4.

FIG. 6 is a schematic diagram illustrating an exposure process in a system in which scattering of a bottom portion is controlled by enhancing surface hardening of a dry film due to the use of a photosensitizer. FIG.

FIG. 7 illustrates the form of the dry film photoresist after the development process after peeling off the photomask and the base film after the exposure process according to FIG. 6.

FIG. 8 illustrates a form of a dry film photoresist in which the content of the polymerization inhibitor is high in the photosensitive resin composition including the polymerization inhibitor, and thus sufficient curing of the bottom portion is not performed, and the circuit is eroded by the developer.                 

Figure 9 shows the form of the dry film photoresist after exposure and development using the dry film photoresist according to the present invention.

      * Description of the symbols for the main parts of the drawings *

1,11-base film, 2,12-photosensitive resin composition layer

Photosensitive resin composition layer after 12'-exposure, hardened site formed by scattering of 12 "-UV

Photosensitive resin composition layer containing 3-polymerization inhibitor

4,14-protective film, 15-sensitizer-containing photosensitive resin layer

Photosensitive resin composition layer containing photosensitizer after 15'-exposure

16-Photomask

20-Hard alkali developable clear coating layer

30-copper foil

The present invention relates to a dry film photoresist, and more particularly, by laminating a photosensitive resin composition layer containing a polymerization inhibitor in addition to the photosensitive resin composition layer, the effect of scattering extra UV energy by copper foil while controlling the overall photocuring profile. It relates to a dry film photoresist that can be implemented by suppressing the fine pattern circuit.                         

Dry film photoresist (DFR) is commonly used to form a circuit on a printed circuit board, which typically contains a photopolymerizable monomer, a photopolymerization initiator, a binder polymer, and an additive. The photosensitive resin composition is dissolved in a solvent and coated on a base film such as PET to form a photosensitive resin composition layer, and has a structure in which a protective film is laminated thereon.

A process of forming a circuit using such a dry film resist will be described with reference to FIG. 3.

Pretreatment is first performed to laminate the copper-clad laminate, which is the raw material of the PCB. The pretreatment process is in the order of drilling, deburring, front, etc. in the outer layer process, the front or pickling in the inner layer process. Bristle brush and Jet pumice processes are mainly used in the front process, and the pickling is subjected to soft etching and 5 wt% sulfuric acid pickling.

In order to form a circuit on a pre-processed copper laminate, the DFR is usually laminated on the copper layer of the copper laminate. In this process, the photoresist layer of the DFR is laminated onto the copper surface while the protective film of the DFR is peeled off using a laminator. In general, the lamination speed is 0.5 to 3.5m / mim, the temperature is 100 to 130 ℃, roller pressure heating roll pressure 10 to 90psi.

After the lamination process, the printed circuit board is left to stand for at least 15 minutes to stabilize the substrate, and then exposed to the photoresist of the DFR using a photomask having a desired circuit pattern. In this process, when the artwork (photomask) is irradiated with ultraviolet rays, the photoresist irradiated with ultraviolet rays is initiated by the photoinitiator contained in the irradiated portion. First, oxygen in the photoresist is consumed initially, and then the activated monomer is polymerized to cause a crosslinking reaction, and then a large amount of monomer is consumed to proceed with the polymerization. On the other hand, unexposed sites are present in a state where the crosslinking reaction is not in progress.

Next, a developing process of removing unexposed portions of the photoresist is performed. In the case of alkaline developing DFR, 0.8 to 1.2 wt% of potassium carbonate (K ₂ CO ₃ ) and sodium carbonate (Na ₂ CO ₃ ) aqueous solution is used as a developer. Used. In this process, the photoresist of the unexposed portion is washed away by the saponification reaction of the developer polymer with the carboxylic acid of the binder polymer in the developer, and the cured photoresist remains on the copper surface.

Next, a circuit is formed through different processes depending on the inner layer and outer layer processes. In the inner layer process, a circuit is formed on the substrate through a corrosion and peeling process, and in the outer layer process, after the plating and tenting process, etching and solder peeling are performed to form a predetermined circuit.

Recently, the dry film photoresist used for IC packaging is urgently required for high resolution and high adhesion. In order to solve this problem, the thickness of the dry film photoresist is getting thinner. Many low-density dry film photoresists have been used that require a lot of exposure energy for photocuring for process margins, process stability and high line adhesion.

Thin film thinning of dry film photoresist is the most important technology trend in recent years. Thin film thinning of low dry film photoresist is proportional to the base part of dry film photoresist because a large amount of exposure energy is irradiated to dry film photoresist. A large amount of exposure energy is irradiated until the extra UV energy is reflected on the surface of the copper foil, causing scattering, which eventually reduces the resolution of the dry film photoresist.

4 to 7, this is a diagram showing a phenomenon in which the resolution of the dry film photoresist is reduced by the scattering effect. FIG. 5 is a view illustrating a form of a dry film photoresist that is subjected to a development process after removing a photomask and then peeling off a base film after the exposure process of FIG. 4.

4 to 5, when a large amount of exposure energy is irradiated to the thin film dry film photoresist, the resolution is reduced due to the hardened portion 12 ″ formed by scattering on the bottom portion of the dry film photoresist.

FIG. 6 is a view illustrating an exposure process in a system in which scattering of a bottom portion is controlled by strengthening the surface hardening of a dry film due to the use of a photosensitizer, and FIG. 7 is a photomask and a base film after the exposure process of FIG. 6. Figure shows the shape of dry film photoresist that has been removed and developed. 6 to 7, the amount of UV energy reaching the bottom is relatively small, hardening of the bottom of the dry film is not high, the pattern 12 'in the form of the inverted leg is formed to secure the width of the circuit after the etching process It shows the difficulty.

In order to overcome the problems shown in FIGS. 4 to 7, a polymerization inhibitor may be added to the photosensitive resin composition. In this case, the polymerization inhibitor may help somewhat to solve the above problems, but the polymerization inhibitor significantly reduces the reactivity of the photosensitive resin composition. There is a problem of making the process very difficult to make it very low.

On the other hand, US Patent No. 5,300,401 discloses a dry film photoresist having a four-layer structure as shown in Figure 2, where the alkali developability between the base film 11 and the photosensitive resin composition layer 12, The technique of obtaining high resolution by reducing the scattering of light by inserting a coating layer 20 of a thin film having no tacky property and removing the base film during the exposure process is disclosed. However, even when the above-mentioned technique is used, the problem of deterioration of resolution in the thin film dry film cannot be fundamentally solved.

Accordingly, the present inventors are working to develop a dry film photoresist having high resolution and high fine line adhesion, and in addition to the photosensitive resin composition layer, by laminating a photosensitive resin composition layer containing a polymerization inhibitor, a copper foil and a photosensitive resin composition layer As a result of placing the photosensitive resin composition layer containing a polymerization inhibitor in the present invention, it was found that the micropattern arc can be realized by suppressing the scattering effect of extra UV energy by copper foil while controlling the overall photocuring profile. It was completed.                         

Accordingly, it is an object of the present invention to provide a dry film photoresist having high resolution and high fine line adhesion.

The dry film photoresist of the present invention for achieving the above object has a structure in which a photosensitive resin composition layer including a base film, a binder polymer, a photopolymerizable monomer, a photoinitiator, and an additive and a protective film are sequentially stacked. The resin composition layer is further laminated between the resin composition layer and the protective film by further adding a polymerization inhibitor to the photosensitive resin composition layer composition.

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

The laminated structure of the dry film photoresist according to the present invention is as shown in FIG.

Referring to FIG. 1, the dry film photoresist of the present invention includes a base film 1, a photosensitive resin composition layer 2, a photosensitive resin composition layer 3 including a polymerization inhibitor, and a protective film 4. It has a structure laminated sequentially.

Here, the resin composition layer (3) containing a polymerization inhibitor is a portion that is directly thermocompressed during the lamination process with the substrate (for example, copper foil, CCL, Glass, etc.) during the manufacturing process of the printed circuit board, the thickness is 0.05 Within 2 micrometers is suitable, Preferably 0.1-1 micrometer is the most suitable.

In addition, the resin composition of the photosensitive resin composition layer (3) containing a polymerization inhibitor is the same as the composition of the usual photosensitive resin composition layer, but further includes a polymerization inhibitor.

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As the polymerization inhibitor used in the photosensitive resin composition layer (3) containing a polymerization inhibitor, hydroquinone and p-tert-petitate are generally used. In addition, benzonquinone, chloranyl, and m-dinitro Benzene, nitrobenzene, N, N, N ', N'-tetramethyl-1,4-phenylenediamine, p-phenyldiamine, sulfur and the like. These are substances that react and stabilize easily with radicals. Representative inhibitors are hydrokinone and p-tert-petitcatechol. Benzonkinone, croranyl, m-dinitrobenzene, nitrobenzene, p-phenylziamine sulfur and the like, and these are easily reacted with radicals to stabilize. Moreover, tri-p-nitrophenylmethyl which is itself a stable radical can also be used as a inhibitor. In addition, various types of commercially available polymerization inhibitors may be included.

In addition, other compositions of the photosensitive resin composition layer 3 containing a polymerization inhibitor, ie, a photopolymerizable monomer, a photopolymerization initiator, a binder polymer, an additive, and the like can be known to those skilled in the art. Bar is not specifically limited.                     

In the dry film photoresist laminated structure, the base film 1, the photopolymerizable resin composition layer 2, the protective film 4, and the like conform to the usual dry film photoresist, and are not particularly limited.

9 shows a circuit shape after the exposure and development processes using a dry film photoresist having a four-layer structure according to the present invention.

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

Example 1

Next, the resin composition layer 3 including the photopolymerizable resin composition layer 2 and the polymerization inhibitor was prepared using the following resin composition having the composition shown in Table 1;

1) Pour solvent into the reactor.

2) Weigh the photoinitiators and polymerization inhibitors in Table 1 and add them to the reactor.

3) Mix at room temperature for 1 hour (500rpm).

4) Add photopolymerizable monomers.

5) Mix at room temperature for 1 hour (500rpm).

6) Add binder polymer.

7) Mix at room temperature for 1 hour (500rpm).

8) Leave at room temperature for 1 hour.                     

9) Prepare the coating.

After preparing the coating solution as described above, the resin composition (2) is coated and dried on the base film (PET, 1) and coated to a thickness of 9.5 μm to form the photosensitive resin composition layer (2). After leaving at room temperature, the resin composition (3) was again coated to a thickness of 0.5 μm to form a photosensitive resin composition layer (3) containing a polymerization inhibitor, followed by lamination of the protective film (4) to the final dry film. The photoresist was completed.

(Unit: parts by weight) Furtherance Resin composition layer (3) Resin composition layer (2) Binder polymer Polymer Binder A 60 60 Photoinitiator Benzophenone 1.0 1.0 4,4 '-(bisdiethylamino) benzophenone 0.5 0.5 additive Lucoco Crystal Violet 3.0 3.0 Toluenesulfonic Acid Monohydrate 0.5 0.5 Diamond Green GH 0.5 0.5 Polymerization inhibitor TMPDA 0.02 - Photopolymerizable monomer 9G 5.0 5.0 APG-400 5.0 5.0 BPE-500 10.0 10.0 menstruum Methyl ethyl ketone 30.0 30.0 TMPDA: N, N, N ', N'-tetramethyl-1,4-phenylenediamine
Polymer Binder A: KOLON Binder Polymer A (Molecular Weight 70,000, Acid Value 120mgKOH / g)
9G: (Polyethylene glycol di-methacrylate, Shinnakamura)
APG-400: (Polypropylene glycol di-acrylate, Shinnakamura)
BPE-10: (2.2 Bis [4- (Acryloxy Polyethoxy] Phenyl] Propane (EO10mol), Shinnakamura)
Lucocrystal violet: (hodogaya)
Diamond green GH: (hodogaya)

Comparative Example 1

In the composition of Table 1, the coating solution was prepared in the same manner as described in Example 1 as the composition of the resin composition layer 2, and then coated and dried on a base film (PET) to coat a 10 μm thickness. The protective film was laminated there to complete the final dry film photoresist.                     

The results of evaluating the physical properties of the dry film photoresist obtained from Example 1 and Comparative Example 1 are shown in Table 2 below.

Example 1 Comparative Example 1 Developing time (second) 19 20 Exposure E (mJ / cm 2) 5/21 SST 70 60 6/21 SST 100 85 7/21 SST 140 120 5/21 SST Sensitivity (21SST) 5 5 Resolution (μm) 20 24 Adhesion (μm) 24 24 1/1 Resolution (μm) 20 26 6/21 SST Sensitivity (41SST) 6 6 Resolution (μm) 22 28 Adhesion (μm) 22 22 1/1 Resolution (μm) 22 30 7/21 SST Sensitivity (41SST) 7 7 Resolution (μm) 26 34 Adhesion (μm) 18 18 1/1 Resolution (μm) 24 35 (Property evaluation method)
Lamination: Manual Laminator (Temperature 110 ° C, Pressure 60psi, Speed 2.5m / min)
Exposure: KOLON TEST ARTWORK for fine pattern, 5kW parallel light exposure device, exposure energy measured by UV photometer on artwork
Phenomenon: concentration 1.0wt%, pressure 1.5kgf / ㎠, break point 50%

From the results of Table 2, when the dry film photoresist of the embodiment is applied, it can be seen that the range is slightly reduced or sufficiently applicable in the process compared to the case of applying the dry film photoresist of the comparative example, particularly noteworthy is that the sensitivity is increased As the difference between resolution and 1/1 resolution became larger, the resolution difference of about 6 to 8 μm was observed in six or more stages. In addition, in an adhesive force, it turns out that an Example and a comparative example show almost the same value.

 As described in detail above, in the case of using a dry film photoresist in which a resin composition layer in which a polymerization inhibitor is added to the photosensitive resin composition is further laminated according to the present invention, extra UV energy by copper foil is controlled while controlling the overall photocuring profile during exposure. It is possible to suppress the scattering effect of the micro pattern circuit can be implemented.

Claims (4)

In a dry film photoresist having a structure in which a base film, a binder polymer, a photopolymerizable monomer, a photosensitive resin composition layer including a photoinitiator and an additive, and a protective film are sequentially stacked, A printed circuit further comprising a resin composition layer (photosensitive resin composition layer including a polymerization inhibitor) further comprising a polymerization inhibitor added to the photosensitive resin composition layer composition between the photosensitive resin composition layer and the protective film. Dry film photoresist for substrate. The dry film photoresist for a printed circuit board according to claim 1, wherein the photosensitive resin composition layer containing a polymerization inhibitor has a thickness of 0.05 to 2 µm. The photosensitive resin composition layer of claim 1, wherein the photosensitive resin composition layer comprises a polymerization inhibitor, hydroquinone, p-tert-petitcatechol, benzonquinone, chloranyl, m-dinitrobenzene, nitrobenzene, p-phenyldiamine, sulfur, Dry film for printed circuit board, characterized in that it comprises at least one polymerization inhibitor selected from N, N, N ', N'-tetramethyl-1,4-phenylenediamine, and tri-p-nitrophenylmethyl. Photoresist. delete

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