KR20030012978A - Manufacturing method of printed circuit board using dry-film resist - Google Patents

Abstract

PURPOSE: A method is provided to improve the resolution and tightness of a resist according to a process change when manufacturing the printed circuit board using a dry film resist. CONSTITUTION: A resist is exposed to light(S40). The resist has a thickness t of 5 micrometer <=t<=100 micrometer but a range of 20 micrometer<=t<=30 micrometer is ruled out. The "t" is thickness of a resist layer between a base film and a cover film of a dry film photoresist. A developing step eliminates a non-exposure part(S50). A heat treatment step(S45) is performed between the exposure step(S40) and the developing step(S50). The heat treatment step(S45) uses one of a heat roll or a heated-air oven. When the heat treatment step(S45) uses the heat roll, the heat roll is heated at a temperature of 80-160°C, at a driving speed of 0.2-5 m/min, and at a pressure of 10-90 psi. When the heat treatment step(S45) uses the heated-air oven, the heated-air oven is heated at a temperature of 30-200°C for 5-600 seconds. A thickness of a resist layer of a dry film photo-resist ranges 5-100 micrometer.

Description

Manufacturing method of printed circuit board using dry-film resist

The present invention relates to a method for manufacturing a printed circuit board using a dry film resist, and more particularly, in the manufacture of a circuit using a dry film resist on a copper laminated board commonly used as a printed circuit board, the resolution of the resist by a process change. And it relates to a manufacturing process of a printed circuit board to improve the fine wire adhesion to implement the miniaturization of the circuit pattern.

A dry film resist (DFR) is generally used to form a circuit on a printed circuit board (PCB), and a manufacturing method of the printed circuit board using the same is schematically illustrated in FIG. 1.

In order to laminate the copper laminate, which is the raw material of the PCB, first, a pretreatment process (S-10) is performed. The pretreatment process is followed by drilling, deburring, and front face in the outer layer process. In the internal process, it goes through the front or pickling.

In order to form a circuit on a copper laminate plate that has been subjected to a pretreatment process, a DFR is generally laminated on the copper layer of the copper laminate (S-20). In this process, a laminator is used to peel off the protective film of the DFR while laminating the resist layer of the DFR on the copper surface. In general, the lamination speed is 0.5 to 3.5 m / min, temperature 100 to 130 ℃, roller pressure heating roll pressure 10 to 90 psi.

After the lamination process, the printed circuit board is left to stand for at least 15 minutes (S-30) to stabilize the substrate, and then exposed to the resist of the DFR using a photomask on which a desired circuit pattern is formed (S-40). In this process, when the ultraviolet rays are irradiated to the photomask, the UV irradiated resist is polymerized by the photoinitiator contained in the irradiated portion. First, the oxygen in the resist is consumed initially, 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, the unexposed site is present in a state where the crosslinking reaction does not proceed.

Next, a developing step (S-50) of removing the unexposed portion of the resist is carried out. In the case of an alkaline developing DFR, an aqueous solution of potassium carbonate and sodium carbonate of 0.8 to 1.2% by weight is used as a developing solution. In this process, the unexposed portion of the resist 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 resist remains on the copper surface.

Next, a circuit is formed through other processes according to the inner layer and outer layer processes (S-60). 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.

When patterning a circuit on a PCB using the DFR as described above, a circuit line width of up to about 0.1 mm can be obtained. However, due to the recent miniaturization, light weight, high performance, and high reliability of electronic devices, high density, high performance, and high precision are also strongly required for printed circuit boards. Accordingly, it is also required to improve the resolution of the DFR and increase the thin wire adhesion.

On the other hand, Applicant has made efforts to increase the resolution and fine line adhesion in response to such a demand, and thus heat treatment of the printed circuit board between the exposure step of the resist and the development step of removing unexposed areas. Post exposure heating 'process was developed, and a patent application (Patent Application No. 98-14380) has been patented for this (Domestic Patent No. 271216).

Looking at this in more detail, as shown in FIG.

In this method, first, the DFR is laminated (S-20) and left (S-30) on top of the substrate subjected to the pretreatment step (S-10) as in the conventional method of FIG. 1, and then a desired circuit pattern is formed. In order to irradiate ultraviolet rays to the resist of the dry film by using a photomask (S-40).

Next, the processed material of the process is heat-treated (S-45). The heat treatment process is conventionally carried out using a heating roll or hot air oven. In the case of using a heating roll, the process is carried out so as to satisfy at least one or more processing conditions of one to three heating rolls, a heating roll temperature of 80 to 160 ° C, a heating roll driving speed of 0.2 to 5.0 m / min, and a heating roll pressure of 10 to 90 psi. In the case of using a hot air oven, the oven temperature was 5 to 600 seconds heat treatment at 80 to 200 ℃.

However, the 'post-exposure heat treatment' process, which is known to increase the resolution and fine wire adhesion, is known to be effective in increasing the basic physical properties of dry film. However, when the hot air oven is used in the field, the workability and productivity are deteriorated. In the case of using a heating roll, strict process control was required in accordance with an increase in the defective rate due to a large amount of fixing defects caused by foreign material contamination of the heating roll.

Applicant has been continuously researched to solve the problem of the 'post-exposure heat treatment' process, as a result of installing a drying stage using infrared light instead of heat treatment through a heating roll or hot air oven, which can be obtained through the heat treatment process While achieving the desired purpose, it is possible to solve the fixed defects caused by foreign materials during the process and to increase the production efficiency has been filed with this application (Korean Patent Application No. 2000-78332).

In more detail, in a method of manufacturing a printed circuit board including pretreatment, lamination, neglect, exposure, and development, an infrared drying step is performed within 5 to 600 seconds between an exposure step of a resist and a development step of removing unexposed portions. It was characterized by performing heat drying.

In such a method, in the manufacture of printed circuit boards and lead frames using dry film resists, the possibility of fixation defects caused by foreign substances in the post-exposure heat treatment can be eliminated and the production efficiency can be increased.

The present invention discloses the effect of a heat treatment process using a dry film photoresist of a certain thickness in the use of an infrared drying stage as a pre-exposure heat treatment process and a subsequently patented heat treatment by the applicant. The purpose is to.

The method of manufacturing a printed circuit board and leadframe using the dry film resist of the present invention for achieving the above object includes pretreatment, lamination, leaving, exposure and development, and the dry film resist having a thickness range as follows. And a heat treatment process between the exposure step of the resist and the development step of removing unexposed portions.

5 μm ≦ t ≦ 100 μm (where t denotes the thickness of the resist layer between the base film and the cover film of the dry film photoresist, except that 20 μm ≦ t ≦ 30 μm)

1 is a block diagram showing a manufacturing process of a general printed circuit board,

2 is a block diagram illustrating a manufacturing process of a printed circuit board including a post-exposure heat treatment process.

3 is a block diagram illustrating a manufacturing process of a printed circuit board including a heat treatment process through an infrared drying stage after exposure;

4 is an image of a test artwork for forming a trace on a CCL to evaluate the followability of a dry film photoresist,

5 is an image after forming a trace on the CCL surface using the artwork of FIG. 4,

6 is an image of test artwork for forming a circuit in a vertical direction above the CCL.

The manufacturing method according to the present invention is a method of forming a circuit pattern on a conventional printed circuit board and lead frame undergoing pretreatment, lamination, leaving and exposure processes, and heat treatment of the cured photoresist after exposure to enable patterning of fine circuits. do.

Specific processes are as shown in Figures 2 and 3, the heat treatment may be any of a heating roll, hot air oven and infrared drying stage.

In the case of using a heating roll, the process is performed to satisfy at least one or more processing conditions of one to three heating rolls, a heating roll temperature of 80 to 160 ° C, a heating roll driving speed of 0.2 to 5 m / min, and a heating roll pressure of 10 to 90 psi. ; In the case of using a hot air oven, the heat treatment may be performed at an oven temperature of 800 to 200 ° C. for 5 to 600 seconds.

When the infrared drying stage is provided, the length of the drying stage is 30 to 300 cm, the temperature is 30 to 150 ° C., and the heat treatment time is performed in a range where thermal curing of the resist does not occur within 5 to 600 seconds. In summary, it is as follows.

30cm≤L≤300cm, 30 ℃ ≤T≤150 ℃, 5sec≤t≤600sec

Where L is the length of the IR drying stage, T is the temperature of the IR drying zone, and t is the residence time of the IR drying stage.

If it is out of the above range, sufficient heat treatment is not performed, so it is difficult to expect a clear resist to improve fine wire adhesion or resolution, and in the case of excessive heat treatment, unexposed resist hardens, causing undeveloped and unpeeled during development and peeling process. Can be.

Among the heat treatment means as described above, in the case of heat treatment using an infrared drying stage during the continuous manufacturing process of a printed circuit board, the problem of a large amount of fixing defects due to the contamination of the heating roller generated when the heating roller is applied is eliminated. In general, the drying efficiency is better than that of hot air drying, which enables effective heat treatment in a short time, and improves circuit properties, that is, sensitivity, resolution, and fine wire adhesion, and thus is the most preferable heat treatment means. However, it is not limited to this.

However, in the dry film photoresist, the heat treatment effect is different depending on the thickness of the resist layer. That is, in the thin film and the thick film film, the independent thin line, the resolution and the followability, which are the basic properties of the dry film photoresist, are remarkably improved. .

In view of this, the thickness of the resist layer of the dry film photoresist is in the range of about 5 to 100 μm, except for the dry film photoresist having a thickness of 20 to 30 μm.

Dry film photoresist is referred to as a thin film dry film photoresist, and a resist layer less than 20 μm and less than 20 μm is referred to as a thick film dry film photoresist having a resist layer thicker than 30 μm and 100 μm or less.

Such thin film or thick film dry film photoresist exhibits improvement in resolution and fine wire adhesion, which are the basic properties of dry film photoresist through heat treatment, and exhibits excellent effects in the following property, which is one of the most important physical properties of dry film. This can contribute to yield improvement.

After the heat treatment process as described above, and proceeds to the subsequent process according to the development and the inner layer, the outer layer process.

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

Example

Next, the DFR having the resist composition shown in Table 1 was laminated on the upper copper layer of the printed circuit board, followed by exposure, heat treatment, and development processes as described below, and physical properties of the cured resist were measured.

However, as a heat treatment method, a heating roller, a hot air oven, and an infrared drying stage were used. The sensitivity, resolution, and thin wire adhesion according to the thickness and exposure amount of the photoresist were measured, and the results are shown in Table 2 below. In case of heat-treatment using heated roller, heat-treated using heat roller temperature of 120 ℃, pressure 80psi, speed of 2.5m / min, and stage of roller stage 2, in case of using hot air oven, set temperature of hot air oven 150 ℃, Heat-treatment time The heat-treatment was performed at 12 seconds exposure, and when heat-treated using an infrared drying stage, the experiment was conducted at an infrared drying zone length of 100 cm, a temperature of 120 ° C., and a speed of 2.5 m / min.

DFR-A Furtherance Content (% by weight) Polymer binder Polymer Binder A 48 Photoinitiator Benzophenone 2.0 4,4 '-(bisdiethylamino) benzophenone 3.0 Luco Crystal Violet 3.0 Toluene Sulphonic Acid Monohydrate 0.5 Diamond Green GH 0.5 Photopolymerizable monomer 9G 15.0 APG-400 5.0 BPE-500 10.0 menstruum Methyl ethyl ketone 13.0

Exposure amount ⁽¹⁾ DFR-A (thickness 10 μm) DFR-A (thickness 20 μm) DFR-A (30 μm thick) Heat treatment method Heat treatment method Heat treatment method I II III IV I II III IV I II III IV Sensitivity ⁽²⁾ 20 7.0 6.7 6.8 6.8 7.0 6.8 6.7 6.5 7.0 6.5 6.7 6.5 30 8.0 7.7 7.5 7.7 8.0 7.7 7.7 7.7 8.0 7.7 7.5 7.4 40 9.0 8.5 8.5 8.7 9.0 8.7 8.6 8.5 9.0 8.5 8.7 8.5 50 10.0 9.8 9.5 9.7 10.0 9.7 9.7 9.7 10.0 9.5 9.7 9.5 Resolution ⁽³⁾ (μm) 20 21 17 16 15 26 24 24 22 28 27 26 24 30 25 20 20 18 30 28 27 27 35 33 33 31 40 30 24 24 23 34 31 31 30 42 40 40 39 50 34 29 30 28 40 38 36 36 45 43 42 42 Fine wire adhesion (㎛) 20 30 20 23 24 35 33 32 31 37 34 34 33 30 25 18 20 20 30 28 28 26 35 32 33 32 40 20 13 18 20 25 23 23 21 30 28 28 27 50 20 12 16 18 25 23 22 20 27 27 25 25 (1) The amount of exposure under the artwork, that is, the amount of exposure the dry film photoresist receives (mJ / cm2). (2) The sensitivity is measured by a Stouffer 21 step tablet. (3) The resolution is between the circuit line and the circuit line. The thickness of the resist is the thickness of the resist layer between the base film and the cover film of the dry film photoresist.Method I: Conditions not subjected to the post-exposure heat treatment process, Method II: Heat treatment using a heating roll, Method III: Heat treatment using a hot air oven, Method IV: Heat treatment using an infrared drying stage Lamination conditions of dry film photoresist: HAKUTO MACH 610i, temperature 115 ℃, pressure 4kgf / ㎠, speed 2.5m / min, preheater temperature 120 ℃ Exposure conditions of dry film photoresist: using Perkin-Elmer's OB7120 parallel light exposure machine Developing conditions of dry film photoresist: developer Na ₂ C O ₃ concentration 1% by weight, 30 ° C temperature, spray pressure 1.5kgf / ㎠, breaking point 50%

From the results of Table 2, it can be seen that the improvement of the resolution and the improvement of the independent thin line are most prominent in the composition of the thin film film composition DFR-A (10㎛), especially when using a heating roll (Method In II), it can be seen that the improvement of the independent thin line appears in the composition of the thin film composition DFR-A (10 μm).

In other words, DFR-A (10㎛), a thin film dry film photoresist, when heat-treated using a heating roll, is considered to have the weakest followability and improved fine wire adhesion, which is relatively thick DFR-A. The improvement in fine wire adhesion is more pronounced than in (30 µm).

In order to confirm this more clearly, the improvement of the physical properties is shown in Table 3 by comparing only the heat treatment process (Method I) and the heat treatment process (Method II) using a heating roll.

Exposure DFR-A (thickness 10 μm) DFR-A (thickness 20 μm) DFR-A (30 μm thick) Heat treatment method Heat treatment method Heat treatment method I II Δ (I-II) I II Δ (I-II) I II Δ (I-II) Fine wire adhesion (㎛) 20 30 20 10 35 33 2 37 34 3 30 25 18 7 30 28 2 35 32 3 40 20 13 7 25 23 2 30 28 2 50 20 12 8 25 23 2 27 27 0

On the other hand, in order to confirm the heat treatment effect on the thick film dry film photoresist was carried out in the same manner as shown in Table 4 below.

Exposure amount ⁽¹⁾ DFR-A (30 μm thick) DFR-A (50 μm thick) DFR-A (thickness 70㎛) Heat treatment method Heat treatment method Heat treatment method I II III IV I II III IV I II III IV Sensitivity ⁽²⁾ 30 8.0 7.7 7.5 7.4 8.0 7.6 7.9 7.5 8.0 7.7 7.5 7.7 40 9.0 8.5 8.7 8.5 9.0 8.8 8.5 8.8 9.0 8.6 8.7 8.5 50 10.0 9.5 9.7 9.5 10.0 9.5 9.7 9.5 10.0 9.6 9.8 9.5 Resolution ⁽³⁾ (μm) 30 35 33 33 31 50 43 42 45 60 57 57 56 40 42 40 40 39 55 53 53 51 65 63 63 59 50 45 43 42 42 60 57 55 54 70 68 64 64 Fine wire adhesion (㎛) 30 35 32 33 32 40 35 38 36 42 38 40 38 40 30 28 28 27 35 32 34 30 35 31 33 30 50 27 27 25 25 30 27 27 26 30 27 29 26 (1) The amount of exposure under the artwork, that is, the amount of exposure the dry film photoresist receives (mJ / cm2). (2) The sensitivity is measured by a Stouffer 21 step tablet. (3) The resolution is between the circuit line and the circuit line. The thickness of the resist is the thickness of the resist layer between the base film and the cover film of the dry film photoresist.Method I: Conditions not subjected to the post-exposure heat treatment process, Method II: Heat treatment using a heating roll, Method III: Heat treatment using a hot air oven, Method IV: Heat treatment using an infrared drying stage Lamination conditions of dry film photoresist: HAKUTO MACH 610i, temperature 115 ℃, pressure 4kgf / ㎠, speed 2.5m / min, preheater temperature 120 ℃ Exposure conditions of dry film photoresist: using Perkin-Elmer's OB7120 parallel light exposure machine Developing conditions of dry film photoresist: developer Na ₂ C O ₃ concentration 1% by weight, 30 ° C temperature, spray pressure 1.5kgf / ㎠, breaking point 50%

From the results of Table 4, in the case of the thick film dry film photoresist, as a result of performing heat treatment, general physical properties, namely, an improvement in the resolution and fine wire adhesion, are shown, but there is no excellent effect as in the thin film dry film photoresist. In terms of follow- ing, which plays a very important role, it showed an excellent effect.

Therefore, following the evaluation of the followability, the results are shown in Table 5.

The evaluation of the followability was carried out using a trace method, specifically, after the grooves having an embossed shape as shown in FIG. 5 are formed on the surface of the CCL using the soft etching method using the artwork as shown in FIG. 4. After laminating the dry film photoresist in the vertical direction, and after forming a circuit as shown in Figure 6 in the vertical direction in the groove was evaluated by counting the number of circuit breaks (open failure). The height of the groove was selected by two types of 10 ± 1㎛ and 25 ± 2㎛, and the height of the groove was measured using a laser scanning microscope and then tested.

DFR-A (30 μm thick) DFR-A (50 μm thick) DFR-A (thickness 70㎛) Heat treatment method Heat treatment method Heat treatment method Trace height (㎛) Circuit width (μm) I II IV I II IV I II IV yield(%) 10 100 65 62 66 88 98 87 94 100 94 150 68 69 67 92 99 92 95 100 95 200 70 73 69 90 99 90 95 100 95 25 100 12 2 10 83 95 83 93 99 92 150 14 5 17 85 93 82 92 100 93 200 10 3 13 88 97 87 93 100 93 Open Defective Count (x / 500) 10 100 175 190 170 60 10 65 30 0 30 150 160 155 165 40 5 40 25 0 25 200 150 135 155 50 5 50 25 0 25 25 100 440 490 450 85 25 85 35 5 40 150 430 475 415 75 35 90 40 0 35 200 450 485 435 60 15 65 35 0 35 (Note) The thickness of the resist refers to the thickness of the resist layer between the base film and the cover film of the dry film photoresist Method I: Conditions not subjected to the post-exposure heat treatment step, Method II: Heat treatment using a heating roll, Method IV: The evaluation of the process followability by heat treatment using the infrared drying stage was evaluated by the Trace method.The yield was compared by counting the number of open by peeling the line / space = 1/1 circuit after etching (70% breaking point). The thickness of the CCL was 1 mm and the copper foil used 2 ounces. Lamination conditions of the dry film photoresist: HAKUTO MACH 610i, temperature 115 ° C., pressure 4 kgf / cm 2, speed 2.5 m / min, preheater temperature 120 ° C. Exposure condition of dry film photoresist: using Perkin-Elmer's OB7120 parallel light exposure machine. Development condition of dry film photoresist: developer Na ₂ CO ₃ concentration of 1% by weight, 30 ° C temperature, spray pressure 1.5kgf / ㎠, breaking point 5 0% etching condition: copper chloride hydrogen peroxide system, breaking point 70%, ORP 540mV

As described above in detail, as a result of confirming the effects of the thin film dry film photoresist and the thick film dry film photoresist in performing the heat treatment between the exposure and the development steps according to the present invention, In the case of a film having a thickness of 5 μm or more and less than 20 μm, the improvement of resolution and fine thin line is remarkable through heat treatment. Although the resolution and fine wire adhesion are improved through this, in particular, it has an excellent effect on the followability which plays a very important role in the yield in PCB manufacturing.

Claims (6)

In the manufacturing method of a printed circuit board, A method of manufacturing a printed circuit board using a dry film resist, characterized in that a heat treatment process is performed between an exposure step of a resist satisfying the following thickness range and a developing step of removing unexposed portions. 5 μm ≦ t ≦ 100 μm Here, t is the thickness of the resist layer between the base film and the cover film of the dry film photoresist. 20 µm ≤ t ≤ 30 µm is excluded. The method of claim 1, wherein the heat treatment is performed using a heating roller or a hot air oven. The method of claim 1, wherein the heat treatment is performed through an infrared drying stage. 3. The heat treatment using the heating roller is carried out in the process conditions of the number of heating rollers 1-5, heating roller temperature 30-160 degreeC, heating roll driving speed 0.2-5.0 m / min, heating roll pressure 10-90psi. Method of manufacturing a printed circuit board, characterized in that performed to satisfy at least one. The method of claim 2, wherein the heat treatment using the hot air oven is performed to satisfy at least one or more of the process conditions of 30 to 200 ° C. and a heat treatment time of 5 to 600 sec. The dry film resist of claim 3, wherein the infrared drying stage is performed to satisfy at least one or more of process conditions consisting of a length of 30 to 300 cm, a temperature of 30 to 150 ° C., and an IR drying stage residence time of 5 to 60 sec. Method of manufacturing a printed circuit board using.