JPH1121359A - Chemical etching method for polyester-based film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form opening sections with fine processing widths on a polyester film by forming resist patterns resistant to an aq. alkaline hydrazine soln. on both sides of the film and etching the film with an aq. alkaline hydrazine soln. SOLUTION: Both sides of a polyester film 1 is pretreated with an org. solvent, of which solubility parameter δs is in the range of the solubility parameter of polyethylene terephthalate, δp=20.5±1.5 (J<1/2> /cm<3/2> ); then, photoresist layers 3 comprising a cyclized rubber-bisazide film are formed on both sides and cured by UV lithography to form resist patterns 4 having opening sections 2 and resistant to, an aq. alkaline hydrazine soln.; the polyester film 1 having resist patterns 4 formed thereon is immersed in an aq. alkaline hydrazine soln. to form exposed opening sections 2; and the cured resist patterns 4 are peeled off with a peeling liq. to give an etched polyester film 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chemical etching method for forming fine openings in a polyester film using an aqueous solution of alkaline hydrazine.

[0002]

2. Description of the Related Art As a method of forming an opening in a polyester film, a processing method by punching has been known for a long time, and has been put to practical use in photographic films and the like. Recently, Japanese Patent Application Laid-Open No.
No. 27 discloses an excimer laser drilling method for producing a plastic mask for cream solder printing. Further, as a chemical etching method, Japanese Patent Application Laid-Open No. Hei 5-21538 discloses a polyester film punched by a chemical etching method as an insulating layer having a via hole used in a film carrier device.

[0003] Among these methods, the punching method is a processing method excellent in mass productivity. However, it is difficult to form an opening smaller than 0.3 mm in width, and the inner wall of the opening is formed by punching. Since it deforms under shearing force, it cannot be formed smoothly. Laser processing method is 0.3
It is possible to form an opening smaller (smaller) than the mm width, which is an excellent processing method, but is unsuitable for processing a film wider than A4 size, and has a problem that the cost is high. On the other hand, the chemical etching method is a method suitable for processing a wide film.
The embodiment of the invention described in Japanese Patent No. 538 relates to a polyimide film, and details of a polyester film are unknown.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a chemical etching method for forming an opening having a fine processing width in a polyester film using an aqueous solution of alkaline hydrazine.

[0005]

In order to achieve the above object, the present inventors have studied the microstructure of conventional polyester fibers, for example, Noboru Yamazaki et al., Journal of the Textile Society, Vol. 30, T-48.
5 (1974) and methods for analyzing terminal carboxyl groups, for example, G. Stein et al., MelliandTe
xtilber Int. 57 volumes, 920 pages (19
Applying the hydrazine decomposition method used in 76) to a polyester film, and by appropriately selecting an etching solution and etching conditions, it is possible to form an opening having a processing width smaller than 0.3 mm without generating cracks. And completed the present invention.

That is, the present invention resides in a method for chemically etching a polyester film, comprising forming a resist pattern of an alkali-resistant hydrazine aqueous solution on both sides of a polyester film and etching the resultant with an alkaline hydrazine aqueous solution.

Further, the present invention provides the above-mentioned invention, wherein the resist pattern of the alkali-resistant hydrazine aqueous solution has a solubility parameter δs [J ^1/2 / cm ^3/2 ] of polyethylene terephthalate having a solubility parameter value δp = 20.
Polyester, characterized by comprising the azido-based film ^{- 5 ± 1.5 [J 1/2 /} cm 3/2] pretreated formed on a polyester film cyclized rubber in an organic solvent in the range of In the chemical etching method of the film.

Further, the present invention provides the method for chemically etching a polyester film according to the above invention, wherein the resist pattern of the alkali-resistant hydrazine aqueous solution is formed of a metal film.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyester film used in the present invention is not particularly limited as long as it is a film made of polyethylene terephthalate and a copolymer thereof, but a polymer or a copolymer having an ethylene terephthalate unit of 90 mol% or more is used. A biaxially stretched film formed from a polyester consisting of: is preferred because of its excellent mechanical properties. For applications requiring heat resistance, a liquid crystal polymer film consisting only of an ester bond, for example, a "Vectra" (trade name) film manufactured by Kuraray Co., Ltd. may be used. The thickness of the film may be 0.5 mm or less in order to form an opening having a processing width of 0.3 mm or less, and the lower limit thereof is about 10 μm.

In forming a resist pattern on a polyester film, a pretreatment of the polyester film with an organic solvent is performed to improve the adhesion between the polyester film and the resist.

The pretreatment of the polyester film in the case of forming a resist pattern comprising a cyclized rubber-bisazide film is performed by removing a stain such as oil adhering to the surface of the polyester film with a specific organic solvent for 3 to 10 minutes. The surface is modified together with the removal. Here, as the specific organic solvent, its solubility parameter δs [J ^1/2 / cm ^3/2 ]
Is within the range of the solubility parameter value of polyethylene terephthalate δp = 20.5 ± 1.5 [J ^1/2 / cm ^3/2 ], and a solvent that dissolves and removes oil and the like is used. In addition,
Polyethylene terephthalate has a solubility parameter of 2
0.5 J ^1/2 / cm ^3/2 is D. W. Van
Krevelen, J .; P. Hoftizer, Pro
parties of Polymers, P143
(Elsevier Sci. Pub. Compan
y) (1976). It is described in.

A preferred solvent that can be used is MEK
(Δs = 19.0), acetone (δs = 20.3), tetrachloroethane (δs = 20.1), 1,4-dioxane (δs = 20.3) and the like. On the other hand, when isopropanol (δs = 23.5) was used, the adhesion between the polyester-based film and the resist layer was not sufficient even if the cleaning treatment time was extended to 10 minutes, and the subsequent etching with an alkaline hydrazine aqueous solution was not performed. In this case, the etching at the interface between the film and the resist layer becomes large, which is not preferable. Although the reason is unknown, it is presumed that the above-mentioned specific solvent has been subjected to surface modification of the film during the washing treatment because of its high affinity for polyester.

On the other hand, in the pretreatment of the polyester film in the case of forming a resist pattern comprising a metal film, a dust-free organic solvent capable of dissolving and removing oil and the like is sufficient.

Hereinafter, the present invention will be described with reference to the drawings. The drawing shows an enlarged section of the etching method,
In the figure, reference numeral 1 denotes a polyester film to be subjected to etching.

A photoresist layer is formed on both sides of the polyester film 1. In FIG. 1A, reference numeral 3 denotes a photoresist layer. As the resin for forming the resist pattern, a resin of a reduced rubber type is preferable from the viewpoint of resistance to an aqueous solution of alkaline hydrazine. These include those obtained by adding an aromatic bisazide crosslinking agent to a cyclized rubber. The resin for forming the resist pattern is uniformly applied to both sides of the film 1, dried and cured by ordinary UV lithography to form a resist pattern 4 of an alkali-resistant hydrazine aqueous solution having an opening 2 (FIG. 1).
(B)).

Next, the polyester film 1 having the resist pattern 4 formed on both sides is immersed and shaken in an aqueous alkaline hydrazine solution to form an opening 2 in the exposed polyester film (FIG. 1 (c)). Finally, the cured resist pattern 4 is peeled off using a peeling liquid to obtain a polyester film having openings 2 by chemical etching (FIG. 1 (d)).

FIG. 2 shows an example in which a metal film is used as a resist. When a metal film is used as a resist, a metal film having a thickness of about 0.5 μm is vapor-deposited on both sides of the polyester-based film 1 and then subjected to electrolytic plating to obtain a film having a thickness of 5 μm.
Is a polyester film in which the metal film 5 is laminated on both sides. Next, a negative type photoresist layer 3 is formed on both sides of the metal film 5 laminated film (FIG. 2A), and the photoresist layer 3 is cured and developed by ordinary UV lithography to form an opening. After forming the cured resist pattern 4 having the portions 2 (FIG. 2B), the exposed metal film 5 is removed by etching to expose the polyester film 1 (FIG. 2C). Next, resist patterns 4 on both sides
Then, a resist pattern of an alkali-resistant hydrazine aqueous solution composed of the metal film 5 is formed (FIG. 2D). As the metal, copper, SUS304, SUS316 and the like can be preferably used. As a means for laminating these metals on a polyester-based film, a means for laminating a metal film by a plating method after forming a conductive film by metal evaporation or the like can be used.

Next, the resist pattern 4 composed of the metal film 5 is subjected to chemical etching to obtain a polyester film having the openings 2 (FIG. 2E). Next, the resist pattern composed of the metal film 5 is removed with a metal etchant such as ferric chloride to obtain a polyester film having an opening 2 similar to that shown in FIG.

In the method of using a metal film as a resist, depending on the application, it may be used with the metal film pattern on both sides shown in FIG. 2D, or it may be used as a mask for cream solder printing. In use, only the metal film pattern on one side may be removed by etching.

Although the hydrazine monohydrate can be used alone for the chemical etching of the polyester film, it is not preferable as a processing method because countless fine cracks are generated around the opening and on the wall surface of the opening. According to the study of the present inventors, when an alkaline hydrazine aqueous solution obtained by adding an alkali metal compound to hydrazine monohydrate is used as an etchant, the generation of cracks is significantly suppressed, and the etching rate at that time is reduced by the alkali metal compound. It has been found that as the amount of addition increases, it accelerates. Further, as an optional component, an amine or alcohol is added in an amount of 30% by volume to hydrazine monohydrate.
It has been found that the addition of the following increases the etching rate.

Examples of the alkali metal compound include an alkali metal hydroxide, an alkali metal carbonate, an alkali metal hydrogencarbonate, and a carboxylic acid alkali metal salt. When the amount is 1% by weight, the generation of cracks is remarkably suppressed, and when the amount is 4% by weight, cracks hardly occur.
The etching rate is accelerated as the amount of addition increases, but is practically in the range of 1 to 30% by weight.

Suitable amines are alkylamines such as propylamine and alkylenediamines such as ethylenediamine, and suitable alcohols are short-chain alcohols such as ethanol and propanol. However, the addition amount is not more than 30% by volume, and if it is added more than that, it is not preferable because the etching rate becomes slow.

[0023]

The present invention will be described below with reference to examples. In the description, “parts” means parts by weight. [Example 1] A polyester film having a thickness of 10
A 0 μm “T-60” (trade name) manufactured by Toray Industries, Inc. was cut into an A5 size and used. First, the polyester film was washed with acetone (δs = 20.3) at room temperature for 5 minutes and then dried, and on one side thereof, “Spinner K-359SD-380A” (trade name) manufactured by Kyowa Riken Co., Ltd. was used. A ring-type rubber-bisazide-based negative photoresist "OMR-83" (trade name) manufactured by Tokyo Ohka Co., Ltd. was applied. After drying at 80 ° C. for 20 minutes, the above photoresist was applied to the other side of the polyester film and dried under the same conditions (FIG. 1A). The thickness of each of the photoresist layers 3 was 12 μm. After transferring a test pattern having a line / space of 0.2 mm width using a diffusion UV exposure device, "OMR8" manufactured by Tokyo Ohka Co., Ltd.
Using a developer for 3 "and a rinse, post-baking was performed at 145 ° C. for 30 minutes using a hot air drier to form a resist pattern 4 having an opening 2 (FIG. 1).
(B)).

Next, 0.4 part of potassium hydroxide was dissolved in 10 parts of hydrazine monohydrate, immersed and shaken in an etchant adjusted to a temperature of 75 ° C. for 15 minutes, and as shown in FIG. The opening 2 was formed in the polyester film 1. The resist layer 3 was stripped with a resist stripping solution for “OMR83” manufactured by Tokyo Ohka Co., Ltd. to obtain a crack-free chemically etched polyester film shown in FIG. 1D.

Example 2 10 parts of hydrazine monohydrate,
Except that etching was performed for 20 minutes using an etchant at a temperature of 70 ° C. consisting of 1 part of ethanol and 0.4 part of potassium hydroxide, all operations were the same as in Example 1 to obtain those obtained in Example 1. Similarly, a crack-free chemically etched polyester film was obtained.

Example 3 100 μm thick Toray Industries, Inc.
A polyester film “T-60” manufactured by cutting into A2 size was used. First, a polyester film 1 was manufactured by Nippon Millipore Industrial Co., Ltd. “Fluorinert Filter”.
(Trade name) After washing with isopropanol dedusted with (pore size 0.2 μm) and drying, copper was added to both surfaces in 0.1 μm.
The thickness of the copper on both surfaces was increased to 5 μm by vapor deposition to a thickness of 5 μm and electrolytic plating. A negative photoresist “PMER N-D40P” (trade name) manufactured by Tokyo Ohka Co., Ltd. is applied to the obtained laminated film 1 having copper 5 on both sides and dried to form a photoresist layer 3 (FIG. 2 (a)). ))
Next, a resist pattern 4 having an opening 2 was formed by UV lithography (FIG. 2B) to expose the copper 5 in the line portion. Next, the laminated film was heated to 40 ° C.
The exposed copper was immersed in ferric chloride for 3 minutes to remove the exposed copper by etching (FIG. 2C), and the resist pattern 4 on the copper 5 was peeled off with a 3% sodium hydroxide solution (FIG. 2).
(D)).

Next, using the patterned copper 5 as a resist, the polyester film 1 was dissolved in 10 parts of hydrazine monohydrate by dissolving 0.4 part of potassium hydroxide at a temperature of 75 ° C.
Immersed in the etchant adjusted to 15 minutes, as shown in FIG.
After the opening 2 is formed as shown in FIG. 1, copper 5 on both sides is removed with a ferric chloride etchant to obtain a crack-free chemically etched polyester film similar to that shown in FIG. 1 (d). Was.

Comparative Example A pretreatment of a polyester film was carried out in the same manner as in Example 1 except that the surface treatment was carried out by washing at room temperature for 10 minutes using isopropanol (δs = 23.5). As a result, the polyester film was not sufficiently adhered to the resist, and the width of the line portion was about 50 μm larger than that of the resist pattern, while the space portion was narrower.

[0029]

According to the present invention, it has become possible to easily perform chemical etching on a polyester film. As a result, openings of large and small sizes can be formed in the polyester film, which is particularly advantageous for forming a pattern in which fine openings having a processing width of 0.3 mm or less are mixed in a film larger than A4 size. Therefore, the polyester film having an opening obtained by the method of the present invention is suitable for producing a cream solder printing mask on a printed wiring board. Further, application to a flexible printed wiring board using a heat-resistant polyester film is also expected.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional explanatory view showing from a state in which a photoresist layer is formed on a polyester-based film to a step in which an opening is formed in the polyester-based film.

FIG. 2 is an enlarged cross-sectional explanatory diagram showing a state from a state in which a metal film is formed on a polyester-based film to a state in which an opening is formed in the polyester-based film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polyester film 2 Opening 3 Photoresist layer 4 Resist pattern 5 Metal film

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshio Yoshihara 1-103-52 Yoshinodai, Kawagoe-shi, Saitama Prefecture Process Lab. Micron Co., Ltd.

Claims (4)

[Claims] 1. A chemical etching method for a polyester film, comprising forming a resist pattern of an alkali-resistant hydrazine aqueous solution on both sides of a polyester film and etching the resultant with an alkaline hydrazine aqueous solution. 2. The resist pattern of an alkali-resistant hydrazine aqueous solution has a solubility parameter δs [J ^1/2 / cm.
^3/2 ] within the range of the solubility parameter value of polyethylene terephthalate δp = 20.5 ± 1.5 [J ^1/2 / cm ^3/2 ]. 2. The chemical etching method according to claim 1, comprising a cyclized rubber-bisazide-based film. 3. The resist pattern of an alkali-resistant hydrazine aqueous solution comprising a metal film.
The chemical etching method as described. 4. The chemical etching method according to claim 1, wherein the alkaline hydrazine aqueous solution comprises hydrazine, water, and an alkali metal hydroxide.