ETCHANT FOR ETCHING WORKPIECES MADE OF ALUMINUM AND ALUMINUM ALLOYS

Abstract

An etchant includes nitric acid (HNO3) having a percentage by mass in the approximate range of 4%-6%, hydrochloric acid (HCl) having a percentage by mass in the approximate range of 1%-3%; and ferric ions (Fe3+) having a concentration in the approximate range of 30-70 grams/liter (g/l). The resultant etchant is suitable for etching aluminum and its alloys. In fact, the etchant is capable of etching such a material to a depth of about 0.1 mm in about 1.8 min, when employed at a temperature in the approximate range of 38° C.-48° C. The etchant further may be recycled, for which an added oxidizer may further be employed.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an etchant, and, particularly, to a kind of etchant used for etching workpieces made of aluminum or an aluminum alloy.

2. Description of Related Art

Workpieces, made of aluminum or an aluminum alloy, are widely used in modern industry. In use, workpieces made of aluminum or an aluminum alloy are oftentimes etched to form apertures, marks, and/or designs on and/or in surfaces thereof. Generally, a typical etchant includes an acetic acid solution, a hydrochloric acid solution, and a nitric acid solution. Such an etchant is usually expensive and cannot be recycled. Additionally, when the etchant of this sort is used to etch workpieces made of aluminium or an alloy thereof, it usually requires a long time to etch the workpieces, and it is prone to leave a residue that stains the workpieces.

Therefore, a kind of new etchant for etching workpieces made of aluminum or an alloy thereof, is desired in order to overcome the above-described shortcomings.

SUMMARY

An etchant includes nitric acid having a percentage by mass in an approximate range from 4% to 6%, hydrochloric acid having a percentage by mass in an approximate range from 1% to 3%; and ferric ions (Fe³⁺) having a concentration in an approximate range of 30-70 grams/liter. The resultant etchant is suitable for etching aluminum and its alloys.

Other advantages and novel features will become more apparent from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

An etchant in accordance with a present embodiment is provided. The etchant can be applied to workpieces made of aluminum or an aluminum alloy, such as housings of mobile phones, computers, digital cameras, etc., in order to form apertures, marks, and/or designs therein and/or thereon, as the case may be. The etchant is a solution including nitric acid (HNO₃), hydrochloric acid (HCl), and a ferric compound.

In the etchant, the percentage by mass of HNO₃ contained in the resulting etchant is in an approximate range from 4% to 6%, and the percentage by mass of HCl contained in the resulting etchant is in an approximate range from 1% to 3%. The ferric (Fe³⁺) compound is a soluble ferric compound. Beneficially, the ferric compound can be a ferric halide chosen from the group consisting of ferric chloride (FeCl₃), ferric bromide (FeBr₃), ferric iodide (FeI₃), and mixtures thereof. When the ferric compound is dissolved in the etchant solution, the concentration of ferric ions (Fe3⁺) contained in the etchant is in the approximate range of 30 to 70 grams/liter (g/l).

In preparation of the etchant, HNO₃, HCl, and the aforementioned ferric compound are mixed in water to form the etchant, wherein an original percentage by mass concentration of HNO₃ is about 68%-70%, and an original percentage by mass concentration of HCl is about 30%-32%. Beneficially, in the etchant an optimal percentage by mass of HNO₃ can be approximately 5%, an optimal percentage by mass of HCl can be approximately 2%, and an optimal concentration of Fe³⁺ can be approximately 50 grams/liter (g/l).

In use, the workpieces made of aluminium or aluminium alloy are immersed in the etchant at a temperature in an approximate range of 38° C.-48° C. to be etched. Beneficially, the optimal etching temperature of the etchant is approximately 43° C. When the workpieces are etched by the etchant for about 1.8 minutes, an etching depth in the workpieces is about 0.1 millimeters (mm). It is to be understood that, for depths greater than 0.1 mm, etching times in excess of 1.8 min would be needed, and for depths of less than 0.1 mm, shorter etching times would suffice. After predetermined apertures, marks, and/or designs are formed in/on the workpieces, the workpieces are taken out from the etchant and cleaned by means of a typical cleaning method, in order to neutralize and/or remove any etchant remaining thereon upon removal from the etchant.

After the etchant is used, it can be recycled for etching further workpieces. An oxidizer, such as sodium chlorate (NaClO₃) or potassium chlorate (KClO₃), can advantageously be added into the etchant for resuming/renewing the oxidizing capability of the used etchant. Beneficially, when an oxidation-reduction potential (ORP) of the used etchant is measured to be less than 550 millivolt (mV), the oxidizer should be added to the used etchant.

Understandably, compared to most kinds of typical etchants, the etchant in accordance with the present embodiment requires less etching time and forms less residue. Additionally, the etchant is less expensive since it can be recycled.

It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of structures and functions of various embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. An etchant comprising:

a nitric acid (HNO3) having a percentage by mass in an approximate range of 4%-6%;

a hydrochloric acid (HCl) having a percentage by mass in an approximate range of 1%-3%; and

a source of ferric ions (Fe3+) having a concentration in an approximate range of 30-70 grams/liter (g/l).

2. The etchant as claimed in claim 1, wherein the percentage by mass of the nitric acid (HNO3) is approximately 5%.

3. The etchant as claimed in claim 1, wherein the percentage by mass of the hydrochloric acid (HCl) is approximately 2%.

4. The etchant as claimed in claim 1, wherein the ferric ions (Fe3+) have a concentration of approximately 50 grams/liter (g/l).

5. The etchant as claimed in claim 1, wherein the etchant is capable of effectively etching aluminum or an alloy thereof at a temperature in an approximate range of 38° C.-48° C.

6. The etchant as claimed in claim 1, wherein the ferric (Fe3+) ions are provided by a soluble ferric compound dissolved in the etchant.

7. The etchant as claimed in claim 6, wherein the ferric compound is chosen from the group consisting of ferric chloride (FeCl3), ferric bromide (FeBr3), ferric iodide (FeI3), and a mixture of at least two kinds of these kinds of ferric halide.

8. The etchant as claimed in claim 1, wherein the etchant further includes an oxidizer.

9. The etchant as claimed in claim 8, wherein the oxidizer is chosen from the group of sodium chlorate (NaClO3) and potassium chlorate (KClO3).

10. The etchant as claimed in claim 1, wherein the etchant is capable of etching at least one of aluminum and an aluminum alloy to a depth of about 0.1 mm in about 1.8 min, when employed at a temperature in the approximate range of 38° C.-48° C.