JP3273825B2 - Method for etching polyimide resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for etching a polyimide resin.

[0002]

2. Description of the Related Art In recent years, polyimide resins having excellent heat resistance, combustion resistance, chemical resistance, various electrical properties, and mechanical strength have been used in various fields. In particular, when used for a flexible printed wiring board (hereinafter abbreviated as FPC) or a film carrier for automatic tape bonding, a substrate is formed using a film-like polyimide, and a part of the polyimide film of the substrate is used. It is necessary to form a through hole by etching. Also,
Even when applied to a structural material such as an aircraft, a chemical etching method is often used as a surface roughening method for improving surface wettability and the like.

On the other hand, conventionally, as a method for etching a polyimide resin, a method using a mixed solution of alkali hydroxide, hydrazine and ethylenediamine has been proposed. However, ethylenediamine is not preferable in terms of work environment because it is easily volatilized and has a strong odor. Furthermore, ethylenediamine is highly toxic and has many safety problems when handled in large quantities. Further, since ethylenediamine has a high volatility, it is necessary to frequently renew the solution, which inevitably results in high cost.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching method capable of performing efficient and highly accurate etching irrespective of the kind of polyimide, providing high safety and reducing costs. Is to be provided.

[0005]

Means for Solving the Problems As a result of intensive studies from the above viewpoint, the present inventors have eliminated the use of amine compounds such as ethylenediamine, which are problematic for use as an etchant, and It has been found that the object of the present invention can be achieved by using dimethyl-2-imidazolidinone (hereinafter abbreviated as DMI), and the present invention has been completed.

That is, the present invention relates to a method for etching a polyimide resin, wherein a solution containing alkali hydroxide, hydrazine and 1,3-dimethyl-2-imidazolidinone as main components is used as an etching solution. In this method, the liquid temperature is 30 to 95 ° C. DMI used in the present invention is a five-membered ring compound represented by the formula (1) or [Chemical Formula 1], and has no odor, low toxicity, and a high boiling point of 225 ° C.
It is a very polar solvent that mixes perfectly with hydrazine.

[0007]

Embedded image DMI is cheaper, easier to handle and safer than ethylenediamine.

The alkali hydroxide used in the present invention may be an alkali carbonate such as potassium carbonate or sodium carbonate, or a hydroxide of an alkaline earth metal such as calcium hydroxide or barium hydroxide. It is a hydroxide of an alkali metal such as sodium oxide, potassium hydroxide and lithium hydroxide. In consideration of the etching efficiency of polyimide, potassium hydroxide is most preferable. This concentration is
Usually, it is about 2 to 25%.

In the polyimide etching solution of the present invention, when the concentration of DMI is increased, the etching accuracy of polyimide is improved. However, considering the workability of mixing hydrazine and DMI, hydrazine / DMI is 99/100 by weight.
1-1 / 99 is practical. Especially when the polyimide film is completely etched, hydrazine / DMI
The weight ratio is more preferably 5/1 to 2/1.

On the other hand, when the concentration of the alkali hydroxide is made higher, the etching efficiency is improved. Considering the etching efficiency and practicality, alkali hydroxide / hydrazine and DM
It is practical that the mixed solution of I has a weight ratio of 1/20 to 1/3. Further, for reasons such as suppression of etching efficiency, further improvement of etching accuracy, or safety issues, the etching solution of the present invention, methanol, ethanol, n-propanol, i-propanol, butanol, alcohols such as phenol, It may be diluted with water or an organic solvent having a relatively high boiling point such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, etc. These diluents may be used alone or as a mixture of two or more. In consideration of the etching efficiency, these diluent components are preferably less than 80% of the liquid composition.

However, in the case of simply using as a roughening treatment of the polyimide resin surface, it is better to take the immersion treatment as long as possible, and to dilute the etching solution with the above-mentioned diluting component by about 2 to 50 times. It is preferable in terms of uniformity.

The etching temperature is not particularly limited, but the temperature of the etching solution is usually about 30 to 95 ° C. The higher the operating temperature is, the higher the etching efficiency is. However, considering the processing accuracy of the through-hole, depending on the liquid composition, it is 60 to 80.
° C is practical. It is also effective to use a solution containing a relatively small amount of an alkali hydroxide component or a low-temperature etching solution for modifying the surface of polyimide, specifically for roughening the surface.

The polyimide which is the target of the etching solution of the present invention is a polyimide film manufactured by Du Pont-Toray Co., Ltd., trade name: Kapton H and Kapton V; a polyimide film manufactured by Ube Industries, trade name: Upilex S and Upilex M Regardless of the type of polyimide, such as polyimide film manufactured by Kaneguchi Chemical Co., Ltd., Apical AH and Apical NPI; polyimide film manufactured by Mitsui Toatsu Chemicals Co., Ltd., Regulus, and polyimide resin manufactured by Mitsui Toatsu Chemical Co., Ltd., Aurum Co., Ltd. At the same time, etching can be performed.

[0014]

【Example】

Example 1 A photoresist (trade name: FSR, manufactured by Fuji Pharmaceutical Co., Ltd.) mainly composed of bisazide-based cyclized natural rubber was applied to the entire surface of a Kapton H having a thickness of 50 μm with a whiteler, and then coated for about 7 hours.
After drying at 0 ° C. for 20 minutes, a resist film of about 7 μm was formed. Next, a predetermined mask is provided on the opposite surface, and 1
The resist was illuminated by irradiating 50 mj of ultraviolet light. Next, the film was developed and dried at 130 ° C. for 20 minutes to obtain a polyimide film partially having an exposed surface with a diameter of 80 μm.

Next, DM was added to 40 g of 98% hydrazine.
30 g of I and 20 g of ethanol were mixed, 10 g of potassium hydroxide was further added, and the mixture was stirred at 70 ° C. for 30 minutes to obtain a polyimide etching solution. The polyimide etching solution was heated to 70 ° C.
It was immersed for 90 seconds while stirring at 00 rpm. A through hole having a diameter of about 81 μm and having a good etching shape was obtained.

Example 2 Kapton H of Example 1 was replaced with 75 μm Regulus for experiments. The etching solution used in Example 1 was heated to 65 ° C., and the polyimide film was immersed in a polyimide etching solution for 90 seconds while stirring at 100 rpm. A through hole having a diameter of about 78 μm and a good etching shape was obtained.

Example 3 Kapton H of Example 1 was replaced with 50 μm Upilex S
And experimented. Next, to 50g of 80% hydrazine,
30 g of DMI was mixed, and potassium hydroxide was added to 2 g.
After adding 0 g, the mixture was stirred at 50 ° C. for 30 minutes to obtain a polyimide etching solution. 80 ° C
The polyimide film was immersed for 180 seconds while stirring at 100 rpm. About 79μm in diameter
Thus, a through hole having a good etching shape was obtained.

Comparative Example 1 The DMI of the etching solution used in Example 3 was changed to ethylenediamine and stirred at 65 ° C. and 250 rpm. Ethylenediamine volatilized, and a strong odor was felt, and the working environment was significantly deteriorated. The waste liquid in which 0.6 g of Iupirex S film was dissolved was allowed to stand in a cool dark place.
After a day, some gelled, and it was very difficult to treat the waste liquid.

Example 4 Copper (18 μm thick) which is a material for an all-polyimide double-sided FPC
m) / polyimide (thickness 50 μm) / copper (thickness 18 μm)
m) Using a laminate (manufactured by Mitsui Toatsu Chemicals Co., Ltd., trade name: Neoflex, product name: NEX-231R (50H))
An exposed surface of polyimide having a diameter of 100 μm was obtained using copper as a mask. It was immersed in the etching solution at 80 ° C. used in Example 3 for 120 seconds without stirring. 100μm diameter
A through hole having a good etching shape was obtained.

Example 5 Next, 250 g of 80% hydrazine was mixed with 90 parts of DMI.
g, mixed, and 60 g of potassium hydroxide was added.
The mixture was stirred at 0 ° C. for 30 minutes to obtain a polyimide etching solution. 0.15 g of each polyimide film of Apical AH, Apical NPI, Kapton H, Kapton V, Upilex S, Uplex M and Regulus was added to this solution,
NEOFLEX; NEX-231R (50H), NEX
-121R (13H) and NEX-100R (251), each film of 0.2 g, and a polyimide / polyimide laminated cover film (neiflex manufactured by Mitsui Toatsu Chemicals Co., Ltd.) as a base material for FPC. / Coverlay) NCF-A1P (25.25), NCF
-O3P (20.25) and N which is a polyimide / polyimide / polyimide laminated bonding sheet (manufactured by Mitsui Toatsu Chemicals Co., Ltd., trade name: NEOFLEX / bond ply)
0.10 g of each product of each model number of BP-m4P (10.25.10) was mixed at the same time, and stirring was continued for 3 hours at 55 ° C. It was confirmed that all of these polyimide films were completely dissolved.

Example 6 The etching solution used in Example 1 was diluted 7.5 times with water and kept at 50 ° C. In the liquid, Kapton H
Was immersed for 5 minutes, taken out and washed thoroughly with water and dried. The wettability of the fill surface was 3 before etching.
It was 6 dyne / cm, but 56 dyne after treatment.
/ Cm or more. It was confirmed that the application of the paint became easy.

[0022]

According to the present invention, since no ethylenediamine is contained, a polyimide etching solution which is less toxic than conventional polyimide etching solutions, is easy to handle, and is inexpensive can be obtained. Furthermore, there is no decrease in the polyimide etching processing accuracy or the etching efficiency. Further, since a plurality of types of polyimides can be dissolved with the same polyimide etching solution, it is more economical.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeyuki Shishido 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside of Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Shigeyuki Takagi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Within Chemical Co., Ltd. (72) Inventor Keisho Tsushima 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Examiner at Mitsui Toatsu Chemicals Co., Ltd. Eiichi Yoshi ▼ (56) References JP-A-6-302586 (JP, A JP-A-3-101228 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J ^7/ 00-7/18 G03F 7/40 H01L 21/56 H01L 21/60 H05K 3 / 00 WPI (DIALOG)

Claims (2)

(57) [Claims] 1. An alkali hydroxide, hydrazine and 1,3
-A method for etching a polyimide resin, wherein a solution containing dimethyl-2-imidazolidinone as a main component is used as an etching solution. 2. The etching method according to claim 1, wherein the temperature of the etching solution is 30 to 95 ° C.