KR20080072027A - Etching solution for thermoplastic polyimide resin - Google Patents

Abstract

As etching liquid for thermoplastic polyimide resin containing alkali metal hydroxide, water, and ethanolamine, the relationship between the said alkali metal hydroxide concentration (X weight%) and the said water concentration (Y weight%) is represented by following formula [1], [2] And [3]:

X ＞ 20 [1]

Y <-X + 60 [2]

Y> 0.25X + 17.5 [3]

By using an etching solution represented by a coordinate point in the region represented by (wherein the total weight of alkali metal hydroxide, water and ethanolamine is 100, and X and Y are defined), a good etching result is also obtained for the thermoplastic polyimide resin. Get

Description

Etching solution for thermoplastic polyimide resin {ETCHING SOLUTION FOR THERMOPLASTIC POLYIMIDE RESIN}

This invention relates to the etching liquid used for the etching process by the wet process of resin which has a thermoplastic polyimide.

2. Description of the Related Art [0002] Conventionally, in the two-layer CCL (copper adhesive laminated plate) polyimide substrate which is widely used as an insulating material for substrates for electronic components, the market demand for low-cost substrates is increasing. In recent years, the market share of laminated base materials obtained by adhering a metal layer such as a copper thin layer or a stainless layer and a polyimide layer through a thermoplastic polyimide has been expanded.

As such a base material, it is marketed a lot from each company concerned, for example, Esperex (Brand name made by Shin-Nitetsu Kagaku Co., Ltd.), Neoflex (Brand name of Mitsui Kaga Co., Ltd.), Uffy Rex VT (Trade name, manufactured by Ubekyo Industries, Ltd.) and the like.

In the laminated base material of these metal layers and a polyimide layer, through-holes, device holes, etc. are formed in a polyimide layer about what is used as a circuit board for electronic components.

Although these holes are conventionally formed by processing light energy (UV irradiation, CO ₂ laser, etc.), they require post-treatment (using potassium permanganate, etc.), or take time for fine hole processing, resulting in poor productivity or a metal layer. For example, a hole is formed by a chemical etching method using an etching solution described in, for example, Japanese Patent No. 3251515, Japanese Patent Application Laid-Open No. 2003-082135, or the like. have.

The etching solution for polyimide resin described in the above-mentioned Patent No. 3251515 is composed of an aqueous solution containing 5-40% ethanolamine, 20-45% potassium hydroxide and the balance of water. As a result of attempting the etching of the laminated base material with the etching solution of the concentration by a plurality of combinations in the region of the composition blending ratio, the effect was recognized for the completely imidized polyimide layer, but the adhesion between the metal layer and the polyimide layer described above. Etching rate was very slow with respect to the thermoplastic polyimide used as the medium of, and there was no adaptability with respect to the raw material containing thermoplastic polyimide, such as the particulate residue of the thermoplastic polyimide.

Moreover, in the component concentration of the etching liquid in the etching method of the laminated body containing a polyimide layer described in Unexamined-Japanese-Patent No. 2003-082135, the water concentration which has compatibility with alkali metal hydroxide and oxyalkylamine is Since it is insufficient, each component is not evenly mixed, and when a dry film is used as a mask material at the time of etching, there exists a problem that the dry film swells and peels and cannot play a role as a mask.

By specifying the component concentration area | region and other component concentration area | region of the etching liquid used for the conventional etching for polyimide resin, this invention can obtain favorable etching result also about the thermoplastic polyimide resin which the etching process result was conventionally bad. It is an object to provide an etching solution for thermoplastic polyimide resin.

Means for solving the problem

The etching liquid for thermoplastic polyimide resin of this invention contains alkali metal hydroxide, water, and ethanolamine, The relationship of the said alkali metal hydroxide concentration (X weight%) and the said water concentration (Y weight%) is represented by following formula [1]. ], [2] and [3]:

X ＞ 20 [1]

Y <-X + 60 [2]

Y> 0.25X + 17.5 [3]

It is an etching liquid represented by the coordinate point in the area | region which satisfy | fills (the total weight of alkali metal hydroxide, water, and ethanolamine is set to 100, and X and Y are prescribed | regulated).

However, following formula [1 '], [1 ″], [2] and [3]:

X ＞ 21 [1 ']

Y <35 [1 ″]

Y <-X + 60 [2]

It is preferable that it is an etching liquid represented by the coordinate point in the area | region satisfying Y> 0.25X + 17.5 [3].

Effect of the Invention

In the etching processing of the thermoplastic polyimide resin using the etching solution in the component concentration region of the present invention, the etching result is significantly shorter than the time required for etching the conventional thermoplastic polyimide resin, and the complete etching result in which no particulate residue of the thermoplastic polyimide is left at all. Can be obtained.

Moreover, since an etching liquid does not pass through the dry film used as a mask material at the time of an etching, the polyimide surface of the part which should be protected by a dry film does not become rough.

BRIEF DESCRIPTION OF THE DRAWINGS It is a graph which shows the component concentration area | region of the alkali metal hydroxide and water in the etching liquid in this invention.

2 is a micrograph showing the etching state of Example 1 of the present invention.

3 is a micrograph showing an etching state of the present invention and Comparative Example 1. FIG.

4 is a micrograph showing an etching state of the present invention and Comparative Example 2. FIG.

It is a figure which shows the result of having etched the CCL polyimide base material containing a thermoplastic polyimide layer using the etching liquid which changed the component concentration of alkali metal hydroxide and water.

FIG. 6 shows the results of etching a CCL polyimide substrate including a thermoplastic polyimide layer by using an etching solution in which the component concentration ranges of the alkali metal hydroxide and water in the etching solution of the present invention and the component concentrations of the alkali metal hydroxide and water are changed. A graph representing.

Fig. 7 is a longitudinal cross-sectional view illustrating the states of not performing etching, insufficient etching, slight etching, completion of etching, and damage to DF (dry film).

The laminated base material used for the circuit board for electronic components consists of bonding a metal layer, such as a copper foil layer or a stainless layer, and the polyimide layer which is an insulating layer through a thermoplastic polyimide resin, and to play a role as an electric circuit to the said metal layer. For this purpose, etching is performed to form through-holes and device holes in desired portions of the polyimide layer containing the thermoplastic polyimide resin, or to form patterns of electrical circuits.

Here, the etchant for thermoplastic polyimide resin in the present invention has been studied in consideration of the absence of an etchant most suitable for etching processing of the thermoplastic polyimide portion contained in the laminate, and, of course, not to mention the polyimide layer. The component concentration area | region which can obtain the favorable etching result even to the thermoplastic polyimide layer was found.

About this invention, what component concentration area | region is different from the component concentration area | region of the etching liquid effective for the etching process of the conventional polyimide, The component concentration area | region is as follows.

That is, the alkali metal hydroxide, water, and ethanolamine are contained, and the relationship between the alkali metal hydroxide concentration (X% by weight) and the water concentration (Y% by weight) shows the concentration region of the alkali metal hydroxide and water in the etching solution of FIG. In the area | region enclosed by the straight line shown by the formula in the graph shown, X = 20, Y = -X + 60, and Y = 0.25X + 17.5, ie, following formula [1], [2], and [3]:

X ＞ 20 [1]

Y <-X + 60 [2]

Y> 0.25X + 17.5 [3]

It is an etching liquid represented by the coordinate point in the area | region which satisfy | fills (it sets X and Y as the total weight of alkali metal hydroxide, water, and ethanolamine as 100).

Moreover, it is preferable to use potassium hydroxide or sodium hydroxide as said alkali metal hydroxide.

Hereinafter, the Example at the time of using the etching liquid of this invention, and the comparative example at the time of using another etching liquid are demonstrated.

<Example 1>

The polyimide and thermoplastic polyimide of the dry film opening part which apply | coated thermoplastic polyimide to the stainless layer which is a metal layer, and laminated the dry film on the laminated base material which adhered the polyimide on it, and patterned the wiring pattern by exposure and image development. Was etched with an etchant having a concentration relationship of 25% potassium hydroxide, 30% water, and 45% ethanolamine for 3 minutes at a temperature of 80 ° C (see the position of the coordinate point of Example 1 in FIG. 1).

As a result of the etching, the polyimide and the thermoplastic polyimide on the stainless layer were completely etched so that no particulate residue of the thermoplastic polyimide was recognized at all, and linearity of the etching surface was also obtained (see FIG. 2).

Comparative Example 1

Using the laminated base material of Example 1 and the same conditions, it etched for 3 minutes at the temperature of 80 degreeC with the etching liquid which has a concentration relationship of 25% of potassium hydroxide, 22.5% of water, and 52.5% of ethanolamine (comparative example in FIG. 1). The position of the coordinate point of 1).

The etching result is that the concentration of ethanolamine is slightly higher than that of the examples, so that the dry film swells, the etching liquid passes through the dry film, and the polyimide surface of the part to be protected by the dry film is partially etched, It was confirmed that a concave-shaped recess was formed (see FIG. 3).

Comparative Example 2

Using the laminated base material of Example 1 and the same conditions, it etched for 3 minutes at the temperature of 80 degreeC with the etching liquid which has a concentration relationship of 25% of potassium hydroxide, 37.5% of water, and 37.5% of ethanolamine (comparative example in FIG. 1). The position of the coordinate point of 2.)

As a result of the etching, the thermoplastic polyimide was not completely etched, and the residue of the granulated thermoplastic polyimide was not completely removed. In addition, even if the etching time is extended, the side etching of the polyimide portion becomes large, and the newly semi-dissolved thermoplastic polyimide remains as a particulate matter (see FIG. 4).

As mentioned above, in the etching process of the polyimide laminated base material containing the thermoplastic polyimide used for electronic components, the etching liquid in the component concentration area | region of this invention shows the outstanding effect about the etching of a thermoplastic polyimide. I knew that.

Moreover, a dry film is laminated on the laminated base material which apply | coated thermoplastic polyimide to the copper layer which is a metal layer using the etching liquid of 20-40% of water and 15-35% of alkali metal hydroxides, and adhered the polyimide on it. And the polyimide and thermoplastic polyimide of the opening part of the dry film which patterned the wiring pattern by exposure and image development were etched. And the etching result was evaluated corresponding to each state shown in FIG. In addition, in FIG. 7, (A) shows the non-etching state (the state which started etching, but since the etching depth is thin, the distinction with other parts is not clear), (B) in FIG. Has progressed to a considerable depth, but the copper at the bottom has not been reached yet. In FIG. 7 (C), the etching is slightly lacking (the etching depth has reached the copper at the bottom, but the copper surface at the bottom is thin. The state in which the residue of the thermoplastic polyimide remains), and (D) in FIG. 7 shows the etching completion state (the etching depth reaches the copper of the bottom surface, and the copper surface is completely exposed also in the bottom part). (E) shows the DF damaged state (the state which the etching liquid passes through the DF mask, the etching liquid enters, and the mark which is considered to be partially etched is recognized in each place) as an etching start state and an end state, respectively. .

The evaluation results are shown in FIG. 5 and FIG. 6. 6, the area | region of the etching liquid of Unexamined-Japanese-Patent No. 10-97081, the area | region of the etching liquid of Unexamined-Japanese-Patent No. 2003-082135, and the area | region of the etching liquid of this invention are each, respectively. It is shown as 10-97081, patent publication 2003-082135, and a claim.

When the alkali metal hydroxide is 30% and the water is 35%, when the alkali metal hydroxide is 35% and the water is 40%, the etching is not performed even if the etching is performed for 12 minutes (see (A) in FIG. 7). ,

When the alkali metal hydroxide is 15%, the water is 20%, 25%, 30%, 35%, 40%, the alkali metal hydroxide is 20%, the water is 20%, 25%, 30%, 40%, alkali When the metal hydroxide is 25%, the water is 20% and 40%, when the alkali metal hydroxide is 30%, the water is 20%, 25% and 40%, the alkali metal hydroxide is 35%, the water is 20% and 25% , 30% and 35%, even if the etching is carried out for 12 minutes, the etching is insufficient (see Fig. 7 (B)), when the alkali metal hydroxide is 20%, water 30%, 40%, alkali metal hydroxide When this 25% and water are 40%, when alkali metal hydroxide is 30% and water is 40%, it is also dry film damage (it calls DF damage) (refer FIG. 7 (E)),

When the alkali metal hydroxide is 20% and the water is 35%, when the alkali metal hydroxide is 21% and the water is 35%, when the alkali metal hydroxide is 22% and the water is 35%, the alkali metal hydroxide is 25% and water In the case of 35%, even though etching is performed for 12 minutes, the etching is slightly insufficient (see FIG. 7 (C)), and dry film damage (called DF damage) (see FIG. 7E) is alkali. When the metal hydroxide is 21% and the water is 30%, when the alkali metal hydroxide is 22%, the water is 25% and 30%, when the alkali metal hydroxide is 25% and the water is 25% and 34%, the alkali metal hydroxide In the case of 29% water and 30% water, even though etching is performed for 12 minutes, the etching is slightly insufficient (see (C) in FIG. 7). When the alkali metal hydroxide is 22% and the water is 34%, 10 minutes. By etching, the etching is completed (see FIG. 7D), and when the alkali metal hydroxide is 25% and the water is 30% Etching was completed by performing etching for 6 minutes (refer FIG. 7 (D)).

From these evaluation results, alkali metal hydroxide, water, and ethanolamine are contained, and the relationship between the said alkali metal hydroxide concentration (X weight%) and the said water concentration (Y weight%) is the difference between the alkali metal hydroxide and the water in the etching liquid of FIG. In the graph showing the concentration region, the region surrounded by the straight lines represented by X = 21, Y = 35, Y = -X + 60 and Y = 0.25X + 17.5, that is, the following formula [1 '], [1 ″] , [2] and [3]:

X ＞ 21 [1 ']

Y <35 [1 ″]

Y <-X + 60 [2]

Y> 0.25X + 17.5 [3]

However, it is preferable that it is an etching liquid represented by the coordinate point in the area | region which satisfy | fills (total weight of alkali metal hydroxide, water, and ethanolamine is prescribed | regulated to X and Y), and it improves etching performance and DF damage. Exclusion can be made compatible.

Claims (2)

As etching liquid for thermoplastic polyimide resin containing alkali metal hydroxide, water, and ethanolamine, the relationship between the said alkali metal hydroxide concentration (X weight%) and the said water concentration (Y weight%) is represented by following formula [1], [2] ] And [3]: X ＞ 20 [1] Y <-X + 60 [2] Y> 0.25X + 17.5 [3] Etching liquid for thermoplastic polyimide resin characterized by the above-mentioned coordinate liquid in the area | region represented by (the total weight of alkali metal hydroxide, water, and ethanolamine being 100, and X and Y are prescribed | regulated). The method according to claim 1, The said area | region is following Formula [1 '], [1 "], [2], and [3]: X ＞ 21 [1 '] Y <35 [1 ″] Y <-X + 60 [2] Y> 0.25X + 17.5 [3] The etching liquid for thermoplastic polyimide resin which is an area | region represented by the.

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