JPH06200385A - Composition for etching iron-base metal and etching method - Google Patents

Abstract

PURPOSE:To obtain a composition for etching iron-base metals excellent in the smoothness of an etched surface, linearity and dimensional precision and with the etching rate promoted. CONSTITUTION:This etchant composition contains 45wt.% ferric chloride, 0.15wt.% free hydrochloric acid, 0.2wt.% of 2-propyne-1-ol, 1.0wt.% diethylene glycol and 0.05wt.% ethylene thiourea. Only ethylene thiourea is added during etching at a rate of 0.05wt.%/hr. Excellent etch factor, etching rate, surface roughness, etc., are obtained. A good condition is maintained by the addition of ethylene thiourea during etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching composition and an etching method used for processing an iron-based metal by photoetching.

[0002]

2. Description of the Related Art Iron-based metals to be photo-etched include mild steel, stainless steel, and iron-nickel alloys. Products processed by this method include lead frames, shadow masks, various display tube meshes. There are many examples such as encoder slits and name plates. In particular, it is a manufacturing technique that is indispensable for fine processing of electronic parts, and with the development of chemical technology in recent years, these products are required to be processed with higher precision and accuracy. There is.

Wet chemical etching using an etchant is
This is performed by forming a desired pattern on the surface of the material to be processed with a chemical resistant resin film and dissolving and removing the exposed metal portion.

[0004]

In the case of the wet chemical etching, the corrosion reaction also acts in the lateral direction and is excessively removed from the exposed metal portion. This is called side etching, but this effect must be minimized in order to support fine processing. Further, it cannot be said that the product has good quality unless the roughness of the etched surface is small and the linearity of the edge portion is secured. Furthermore, in order to improve mass productivity, it is necessary to accelerate the etching rate as much as possible.

Taking a semiconductor lead frame as an example, LS
As the degree of integration of I increases, the degree of miniaturization progresses,
It has been desired to have a large number of pins and a narrow pin interval.

Therefore, it is an important subject in terms of manufacturing cost to cope with this and to improve the yield of products.

The same applies to other products requiring high density, and various studies have been conducted in terms of processing materials, equipment, composition of etching solution and processing conditions.

In the past, in order to solve these problems, many proposals have been made from a method for producing a raw material, for example, Japanese Laid-Open Patent Publication No. 2-217442, but the description examined based on the composition of the etching solution is not very much. I can't see it.

As an additive to the aqueous ferric chloride solution,
JP-A-1-301869 proposes an etching-promoting additive containing acetylene alcohol or its alkylene oxide adduct and alkane sulfonic acid, alkanol sulfonic acid or salts thereof as essential components. Is not enough to get the effect.

Further, in JP-A-2-141589, four components of alkanesulfonic acid, hydroxyl group-containing alkanesulfonic acid or salts thereof, acetylene alcohol or acetylene alcohol alkylene oxide adduct, polyethylene glycol and organic phosphorus compound are essential. Although an etching accelerator as a component has been proposed,
It is difficult to obtain satisfactory results even with this additive.

The object of the present invention is to smooth the etched surface,
It is an object of the present invention to provide an iron-based metal etching composition and an etching method which are excellent in linearity, acceleration of etching rate, and dimensional accuracy.

[0012]

The present invention provides a composition for etching an iron-based metal, which comprises the following components (a), (b), (c), (d) and (e): is there.

(A) ferric chloride aqueous solution (b) hydrochloric acid (c) acetylene alcohol having 3 to 6 carbon atoms (d) polyhydric alcohol (e) -S- group, -SH group or> C = S group Organic Sulfur Compound Containing The present invention is also characterized in that the concentration of ferric chloride as the component (a) is 30 to 55% by weight of the composition for etching an iron-based metal.

Further, the present invention is characterized in that the concentration of hydrochloric acid as the component (b) is 0.01 to 0.50% by weight of the iron-based metal etching composition as the concentration of free hydrochloric acid.

In the present invention, the concentration of the acetylene alcohol as the component (c) is 0.
It is characterized in that it is from 01 to 1.0% by weight.

In the present invention, the concentration of the polyhydric alcohol as the component (d) is 0.01% of the iron-based metal etching composition.
˜5.0% by weight.

Further, in the present invention, the concentration of the organic sulfur compound of the component (e) is 0.00 of the composition for etching of iron-based metal.
It is characterized by being 1 to 0.50% by weight.

The present invention also provides the following components (a), (b),
An iron-based metal etching method is characterized in that etching is performed using an iron-based metal etching composition containing (c), (d) and (e).

(A) ferric chloride aqueous solution (b) hydrochloric acid (c) acetylene alcohol having 3 to 6 carbon atoms (d) polyhydric alcohol (e) -S- group, -SH group or> C = S group Organic Sulfur Compound Containing The present invention is also characterized in that the component (e) is added during etching.

[0020]

The aqueous solution of ferric chloride of the component (a) used in the present invention has a porosity of 35-55 Baume, preferably 40-50.
Baume, more preferably 45-47 Baume. The concentration of ferric chloride contained in the etching composition of the present invention is preferably 30 to 55% by weight, more preferably 4
5 to 55% by weight. The reason is that if it is less than 45% by weight, the etching rate is high, but the roughness becomes large and the etch factor is deteriorated, and if it is more than 55% by weight, the etching rate is slow and it is not practical.

The concentration of the component (b), hydrochloric acid, is from 0.01 to 0.01 as the concentration of free hydrochloric acid contained in the etching composition.
It is preferably in the range of 0.50% by weight, and 0.03
The range of ˜0.25% by weight is more preferable. This is because if it is less than 0.01% by weight, it is difficult to obtain the uniformity of the line width, and if it is more than 0.50% by weight, the adhesiveness of the resist is adversely affected and the side etching is increased to lower the etch factor.

Specific examples of the acetylenic alcohol having 3 to 6 carbon atoms as the component (c) include 2-propyn-1-ol, 1-heskin-3-ol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 2-butyne-1,4-diol and the like can be mentioned, and the amount of the component (c) contained in the etching composition is 0.0.
It is preferably 1 to 1.0% by weight, and 0.1 to 0.
It is more preferably 5% by weight. 0.01% by weight
This is because it is difficult to obtain the linearity of the edge portion of the etched metal when the concentration is less than 1.0%, and it is not economical when the concentration is more than 1.0% by weight.

Specific examples of the polyhydric alcohol as the component (d) include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexylene glycol,
Examples thereof include glycerin and polyethylene glycol having an average molecular weight of 300 or less. The preferred concentration of the component (d) contained in the etching composition is 0.1 to 5.0% by weight.
And a range of 0.1 to 2.5% by weight is more preferable. If it is less than 0.1% by weight, the wetting of the metal surface is not sufficient and it is difficult to obtain smoothness. Further, if it exceeds 5.0% by weight, it is not economical.

Examples of the organic sulfur compound containing -S- group, -SH group or> C = S group of the component (e) include compounds represented by Chemical formula 1, Chemical formula 2 and Chemical formula 3.

[0025]

## STR1 ## R1- (S) in n-R2 Formula 1, R1, R2 is - a (CH ₂₎ m-R3,
It may be the same or different. R3 is -OH, -NH _2,
It is -COOH and is an integer of m = 1 to 4 and n = 1 to 2. When R3 is -COOH, it may be a salt with an alkanolamine having up to 6 carbon atoms. Also, R3 is -N
In the case of H ₂ , a salt with an inorganic acid or a carbon number of 1 to
It may be a salt with the organic acid of 3.

Specific examples of compounds corresponding to these include thioalcohols such as thiodiglycol, thiodipropanol, thiodibutanol, dithiodiglycol, dithiodipropanol and dithiodibutanol, thiodiethylamine, thiodipropylamine. , Thiodibutylamine, dithiodiethylamine, dithiodipropylamine, dithiodibutylamine and the like, and hydrochlorides, phosphates and acetates of said thioamines, also thiodiglycolic acid, thiodipropionic acid, thiodibutyric acid , Thiodivaleric acid, dithiodiglycolic acid, dithiodipropionic acid, dithiodibutyric acid, dithiodivaleric acid and the like, and mono-, di- and triethanolamine salts of the thioacids.

[0027]

Embedded image In the chemical formula 2, R2 is the same as above, and R4 is H or an alkali metal salt.

Specific examples of the compounds corresponding to these include mercapto alcohols such as thioglycol, mercaptopropanol and mercaptobutanol, mercaptoamines such as mercaptoethylamine, mercaptopropylamine and mercaptobutylamine, and hydrochlorides of the above mercaptoamines. , Phosphates and acetates, mercaptos such as thiodiglycolic acid, mercaptopropionic acid, mercaptobutyric acid and mercaptovaleric acid, and mono-, di- and triethanolamine salts of the mercaptos, and the mercaptos and mono , And di- and triethanolamine salts with alkali metal mercaptides.

[0029]

[Chemical 3]

R5 and R6 in Chemical formula 3 may be the same or different and each is hydrogen, an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 1 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an alkylaryl. A group (an alkyl part having 1 to 8 carbon atoms and an aryl part having 6 to 10 carbon atoms), 7 to 11 carbon atoms
Represents an aralkyl group and an alkanol group having 1 to 6 carbon atoms.

[0031]

[Chemical 4]

R7 in Chemical formula 3 is a chemical formula 4 or an alkyl group having 1 to 4 carbon atoms, and R8 and R9 have the same contents as R5 and R6.
R8, R9 and R5, R6 may be condensed with each other to form a ring.

Specific examples of compounds corresponding to these include thiourea, mono-, di- and trimethylthioureas, diethylthiourea, dibutylthiourea, allylthiourea,
Examples thereof include hydroxyethylallylthiourea, diphenylthiourea, ditolylthiourea, dibenzylthiourea, thioacetamide and ethylenethiourea.

The concentration of component (e) in the etching composition is preferably in the range of 0.001 to 0.50% by weight, more preferably 0.01 to 0.40% by weight. If it is less than 0.001% by weight, the effect of surface smoothness and side etching is poor, and if it is more than 0.50% by weight, the improvement of the effect is small. In addition, the substance may be mixed continuously with other substances simultaneously or separately,
When continuously mixed, there is an advantage that the above-mentioned effect is highly durable.

[0035]

EXAMPLES Hereinafter, examples and comparative examples will be specifically described.

Examples 1 to 10 and Comparative Examples 1 to 3 Mild steel plate having a length and width of 200 mm and a plate thickness of 0.25 mm, 42%
A Ni-Fe alloy plate and a SUS304 steel plate each having a pattern with a line width of 85 μm with a water-soluble resist on the front and back were used as substrates, and the temperature was 50 ° C. and the spray pressure was 1.5 kg /
Etching was performed under the condition of cm ² .

The test results were evaluated by the following method.

Evaluation Method The etching rate (ER) was expressed as the engraving depth per unit time after etching from one surface to about half the plate thickness. The unit is μm / min.

The etch factor (EF) was obtained by the same equation as above, using the resist opening width (W1), the opening width (W2) after etching, and the depth (D) in accordance with Equation 1.

[0040]

[Equation 1] EF = 2D / (W2-W1) For the finish, the parts punched from the top and bottom were photographed with a scanning electron microscope, and the smoothness, linearity, and uniformity of the line width of the etched surface were judged. The evaluations are shown by "Good" and "No".

Table 1 shows the composition of the etching compositions used in this example and comparative examples. In addition, Table 2 shows the results of treating each material.

As can be seen from the results shown in Table 2, the etching composition of the present invention has a good finish on the treated surface.
It can be seen that, although the acceleration rate of the etching rate is high, the finish is poor and the etch factor is low in the comparative example.

[0043]

[Table 1]

[0044]

[Table 2]

Examples 11 and 12 42% Ni-F having a length and width of 200 mm and a plate thickness of 0.25 mm
Line width 85 μm with water-soluble resist on the front and back of e-alloy steel plate
Etching was performed at a temperature of 50 ° C. and a spray pressure of 1.5 kg / cm ² as a substrate on which the pattern of FIG.

45% by weight of ferric chloride, 0.15% by weight of free hydrochloric acid, 0.2% by weight of 2-propyn-1-ol, 1.0% by weight of diethylene glycol and 1.0% by weight of ethylene thiol with respect to the etching liquid composition. Urea was adjusted to each concentration of 0.05% by weight and used, and this is used as Example 11.
Under the conditions of Example 11, ethylene thiourea alone was then added.
Example 12 is a case where the mixture was continuously added and mixed at a rate of 05% by weight / hour. The effects of Examples 11 and 12 were compared. The test results are shown in FIG. 1 to FIG. 3 by dotted line in Example 11 and solid line in Example 12. FIG. 1 is a graph showing the relationship between time and etch factor.
Is a graph showing the relationship between time and etching rate,
FIG. 3 is a diagram showing the relationship between time and surface roughness. In addition,
The evaluation method was the same as in Examples 1-10.

As shown in FIGS. 1 to 3, in the case of Example 11 in which ethylenethiourea was not continuously added, each effect was deteriorated after 1 hour or more, while continuous addition was performed. In the case of Example 12, it can be seen that the sustainability of the effect is maintained.

[0048]

According to the present invention, the finish of the treated surface (that is, the smoothness, the linearity, the uniformity of the dimensions) accompanying the miniaturization of the etching pattern, the acceleration of the etching rate and the durability of the effect are excellent. An iron-based metal etching composition and an etching method using the same can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between time and etch factor.

FIG. 2 is a graph showing the relationship between time and etching rate.

FIG. 3 is a graph showing the relationship between time and surface roughness.

Claims (8)

[Claims] 1. The following components (a), (b), (c),
An iron-based metal etching composition comprising (d) and (e). (A) ferric chloride aqueous solution (b) hydrochloric acid (c) acetylene alcohol having 3 to 6 carbon atoms (d) polyhydric alcohol (e) organic sulfur containing -S- group, -SH group or> C = S group Compound 2. The etching of iron-based metals according to claim 1, wherein the concentration of ferric chloride as the component (a) is 30 to 55% by weight of the composition for etching iron-based metals. Composition. 3. The concentration of hydrochloric acid as the component (b) is from 0.01 to 0.01 of the composition for etching an iron-based metal as the concentration of free hydrochloric acid.
0.5% by weight of the iron-based metal etching composition according to claim 1 or 2. 4. The concentration of the acetylene alcohol as the component (c) is 0.01 to 1.
The composition for etching an iron-based metal according to any one of claims 1 to 3, wherein the composition is 0% by weight. 5. The concentration of the polyhydric alcohol of the component (d) is
The iron-based metal etching composition according to claim 1, which is 0.01 to 5.0% by weight of the iron-based metal etching composition. 6. The concentration of the organic sulfur compound as the component (e) is
0.001-0.50 of iron-based metal etching composition
The composition for etching an iron-based metal according to claim 1, wherein the composition is an iron-based metal. 7. The following components (a), (b), (c),
An iron-based metal etching method, which comprises performing etching using an iron-based metal etching composition containing (d) and (e). (A) ferric chloride aqueous solution (b) hydrochloric acid (c) acetylene alcohol having 3 to 6 carbon atoms (d) polyhydric alcohol (e) organic sulfur containing -S- group, -SH group or> C = S group Compound 8. The method for etching an iron-based metal according to claim 7, wherein the component (e) is added during the etching.