KR20150086837A - an aluminum alloy for die casting used in an electronic device and a manufacturing method thereof - Google Patents

Abstract

The present invention relates to a die casting aluminum alloy used in an electronic device and a manufacturing method thereof. More specifically, the present invention relates to a die casting aluminum alloy used in an electronic device and a manufacturing method thereof which provides significantly improved mechanical strength compared with the conventional method. The die casting aluminum alloy used in an electronic device contains 0.7-1.2 wt% of Mg, below 5.5 wt% of Cu, below 4.5 wt% of Zn, below 10.0 wt% of Si, and inevitably the remnant Al and other substances.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy for die casting used in electronic equipment and an aluminum alloy for die casting used in an electronic device and a manufacturing method thereof,

The present invention relates to an aluminum alloy for die casting used in electronic equipment and a method of manufacturing the same. More particularly, the present invention relates to an aluminum alloy for die casting, which is used in electronic equipment with remarkably improved mechanical strength, and a method for manufacturing the same.

Currently, with the development of the IT industry, notebook PCs and electronic component cases are gradually becoming thinner and becoming multimedia-convergence, and due to the rapid spread of portable information terminals such as mobile phones and notebooks, There is an increasing demand for non-ferrous metal alloys (Mg-Al alloys) mainly composed of magnesium and aluminum as materials such as brackets.

Pure magnesium has a high activity and is not only highly resistant to ignition during processing such as casting and polishing but also is not suitable for use as a structural material in general properties such as strength and corrosion resistance. However, when magnesium is alloyed with aluminum or the like, .

For example, when aluminum is added to a magnesium alloy, mechanical properties can be improved. When Mn is added, not only the corrosion resistance can be improved, but the addition amount of Fe, Cu, and Ni can be reduced by the amount. The strength is improved. When Zn is added, corrosion resistance and strength are improved, and when Si is added, the creep strength is improved.

Among these magnesium alloys, case and bracket of electronic products are manufactured by die casting. Alloy suitable for such die casting is AZ91 alloy which shows high tensile and yield strength even in die casting and die casting and also as pressure resistant material.

Korean Patent Publication No. 2005-73550 discloses AZ91 alloy related patent document. AZ91 alloy (about 90% of Mg, about 9% of Al, and 1% of other) has various advantages such as easy processing, high strength and suitability for recycling.

The above technique is characterized in that 0.1 to 1.5% by weight of Si, 0.1 to 1.2% by weight of misch metal containing a rare earth element, based on AZ91 alloy of Al 6.0 to 11.0% by weight, Zn 0.1 to 2.5% by weight and Mn 0.1 to 0.5% 0.1 to 1.5% by weight of antimony and 0.05 to 3.5% by weight of Ca and 0.1 to 1.5% by weight of strontium 0.1, based on the AZ91 based base alloy, To 2.5 wt.% Of a magnesium alloy, and other inevitably contained components, and a method of producing a magnesium diecast product using the same.

However, recently, in view of the trend of lighter and slimmer IT products, there is a need for an aluminum alloy which is thinner and stronger than the conventional one.

An object of the present invention is to provide an aluminum alloy having superior mechanical strength and a method of manufacturing the aluminum alloy.

In order to accomplish the above object, the present invention provides a method for manufacturing an electronic device, which comprises 0.7 to 1.2% by weight of Mg, 5.5% by weight or less of Cu, 4.5% by weight or less of Zn and 10.0% or less by weight of Si, The present invention provides an aluminum alloy for die casting used in a device.

The aluminum alloy for die casting is characterized in that 4.5 to 5.5 wt% of Cu is contained, 3.5 to 4.5 wt% of Zn is contained, and the Si is further included in 8.0 to 10.0 wt%.

0.6 to 1.0 wt% of Fe, 0.2 wt% or less of Mn, 0.1 to 0.3 wt% of Ni, 0.1 wt% or less of Sn and 0.15 to 0.25 wt% of Ti.

The present invention also relates to a method of manufacturing a semiconductor device, comprising: melting an aluminum material; Adding an alloy component to the molten aluminum; Wherein the aluminum alloy component comprises 0.7 to 1.2% by weight of Mg, not more than 5.5% by weight of Cu, not more than 4.5% by weight of Zn, not more than 10.0% by weight of Si, the balance Al and other components are inevitable The present invention also provides a method for producing an aluminum alloy for die casting, which is used in an electronic apparatus.

The melting temperature is maintained at 650 to 750 ° C, and the casting temperature is maintained at 600 to 700 ° C.

In the method for manufacturing an aluminum alloy for a die casting, Cu is included in an amount of 4.5 to 5.5 wt%, Zn is contained in an amount of 3.5 to 4.5 wt%, and Si is included in an amount of 8.0 to 10.0 wt%.

In addition, the method for producing an aluminum alloy for die casting further comprises 0.6 to 1.0% by weight of Fe, 0.2% by weight or less of Mn, 0.1 to 0.3% by weight of Ni, 0.1% by weight or less of Sn and 0.15 to 0.25% do.

According to the present invention, the mechanical strength is improved.

That is, the tensile strength, the yield strength, the elastic modulus, and the maximum load are improved as compared with the prior art, and therefore, they are more resistant to external impact than the prior art, and their external strain is less than that of the conventional art .

Particularly, the thickness of parts such as a case, a cover or a bracket becomes thin in accordance with the tendency of a product to be slimmed recently. In the conventional case, when a strong impact is externally applied to such a product, The technical effect of preventing such a problem can be realized by the present invention.

Fig. 1 shows a procedure of a method for producing an aluminum alloy according to the present invention.
2 is a graph of stress-strain of an aluminum alloy for die casting used in an electronic device according to the present invention.
3 is a stress-strain graph of a prior art ADH-5V aluminum alloy.
4 is a stress-strain graph of an ALDC12 aluminum alloy according to the prior art.
5 is a graph of stress-strain of AZ91D magnesium alloy according to the prior art.
6 is a stress-strain graph for comparison of alloys according to the present invention and prior art

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In the case of an aluminum alloy for a die casting (hereinafter referred to as "aluminum alloy") used in an electronic device according to the present invention, the Al component includes Mg, Cu, Si and Zn components and further contains Fe, Mn, And other inevitably included components.

The content ratio of each component contained in the aluminum alloy of the present invention is shown in the following table.

division

Cu
Si
Mg
Zn
Fe
Mn
Ni
Sn
Ti
Al
content
range

4.5 ~
5.5
8.0 ~
10.0
0.7 ~
1.2
3.5 ~
4.5
0.6 ~
1.0
0.2
Below
0.1 ~
0.3
0.1
Below
0.15 ~
0.25
Balance

(Unit: wt%)

The main components included in the aluminum alloy according to the present invention are as follows.

Mg (magnesium) shows an effect of increasing the strength of the alloy while reducing the specific gravity. In addition, Mg maintains the ductility of the alloy and improves the corrosion resistance and strength, and Mg of 1 wt% or less increases the mechanical properties by refining Si (silicon).

However, when added in large amounts, there is a problem that inclusions and intermetallic compounds are formed and the flowability of the molten metal is lowered. Also, there is a problem that cracking occurs during casting due to the lack of fusion with Al.

On the other hand, since the strength increase width is relatively smaller than that of Cu (copper) to be described later, it is preferable to add a small amount of wt% for the purpose of increasing the strength.

The aluminum alloy according to the present invention preferably contains Mg in a range of 0.7 to 1.2 wt%.

In the case of Cu (copper), as the content increases, the strain resistance increases with the increase of the solubility, thereby contributing to the increase of the strength of the alloy. However, it does not affect 0.4 wt% or less, and the effect of increasing the strength is shown from above.

On the other hand, the solubility of Cu in Cu is 5.65 wt% at the maximum, and Cu or more is present as an intermetallic compound, which causes a decrease in mechanical strength.

The aluminum alloy according to the present invention preferably contains Cu in a range of 4.5 to 5.5 wt%.

In the present invention, Cu is added to the vicinity of the maximum solubility (5.65 wt%) to increase the strength, and in the case of Mg, about 0.7 to 1.2 wt% (preferably 1 wt %).

On the other hand, in the case of Zn (zinc), it has an effect of refining the crystal grains and increasing the strength. When added simultaneously with zirconium, the grain refinement effect is further increased, and an alloy containing iron or nickel has an effect of improving corrosion resistance

When Zn is added, high strength can be achieved through heat treatment. However, when the amount is more than 5 wt%, the effect is not shown.

The aluminum alloy according to the present invention preferably contains Zn in a range of 3.5 to 4.5 wt%.

Si (silicon) is a main component for improving the fluidity of the alloy in the molten state during the die casting process, and the alloy obtained by adding it shows low heat shrinkage and narrow freezing point range, thus exhibiting good high temperature heat resistance, dryness and good welding characteristics.

For this purpose, the aluminum alloy according to the present invention preferably contains about 8.0 to 10.0 wt% of Si.

On the other hand, Fe (iron) is a component that is typically added to an aluminum alloy for die casting in order to prevent the aluminum-magnesium alloy from sticking to the die during the die casting process and to increase the de-formation of the aluminum alloy from the die.

The amount added may be in the range of 0.6 to 1.0 wt%.

Exceeding this range is not preferable because the extensibility of the aluminum-magnesium alloy is reduced.

On the other hand, Mn (manganese) is added to the aluminum alloy for the purpose of eliminating the negative addition of iron. Mn forms a compound that has a strong solid solution strengthening effect and does not harm corrosion resistance.

However, excess Mn may lower the mechanical strength of the aluminum alloy, so that it is preferable that the amount of Mn is 0.2 wt% or less.

Ti (titanium) improves the mechanical properties due to grain refinement. When the content is less than 0.15 wt%, the desired effect is not obtained. When the content exceeds 0.25 wt%, brittleness is caused. .

The manufacturing procedure of such an aluminum alloy is as shown in Fig.

First, the Al material is dissolved in the melting furnace in the range of approximately 700 ± 50 ° C (S1). When the temperature is higher than 750 ° C, the solidification structure becomes ferrite and the tensile strength and hardness are lowered. Therefore, it can not be used for interior and exterior materials of mobile phones and electronic products.

On the other hand, the above-mentioned alloy components are then added to the melting furnace by the respective component content ranges (S2).

At this time, the temperature range of 700 ± 50 ° C can be maintained, and the components of the melted aluminum alloy are interim inspected using a predetermined measuring equipment (S3).

If there is an insufficient amount of alloying element, the proportion of the alloying element is added and the ratio is adjusted (S4).

When the content of each component in the molten alloy meets the standard and the dissolved state also meets the standard, a degassing process is performed (S5) and a casting process is carried out to make it an ingot (S6 ).

The casting temperature is preferably 650 占 50 占 폚, and the temperature of the casting mold is preferably 40 占 폚 or higher.

When the casting process is completed, the appearance of the ingot is inspected (S7), and a specification inspection is performed to determine whether the component satisfies the standard specification (S8).

The aluminum alloy for die casting of the present invention made through the above process is compared with other conventional alloys as follows.

The main components of the aluminum alloy ALDC12 and ADH-5V used in the prior art are as follows.

division

Cu
Si
Mg
Zn
Fe
Mn
Ni
Sn
Ti
Al
ALDC
12
1.5 ~
3.5

9.6 ~
12.0
0.3
Below
1.0
Below
0.6 ~
1.0
0.5
Below
0.5
Below
0.2
Below
-
Balance
ADH-
5V
1.0

Below
0.9 ~
1.5 ~

7.0 to 10.0
0.2 ~
0.4
1.0.
Below
0.1 ~
0.2
0.1
Below

0.1
Below
0.1 ~
1.5
Balance

(Unit: wt%)

The compositional ratio of the aluminum alloy for die casting according to the present invention to the above-mentioned ALDC12 and ADH-5V is 4.5 to 5.5% by weight, which is higher than that of ALDC12 and ADH-5V in the present invention. Thereby contributing to increase the mechanical strength of the aluminum alloy for die casting.

On the other hand, in the case of Mg, 0.7 to 1.2% by weight is included, and the mechanical properties of the alloy are improved by optimizing the range of Si microstructure.

As described above, when Zn is added, a high strength can be achieved through heat treatment. The content of Zn of the present invention is significantly higher than that of the above-mentioned ALDC12 and ADH-5V by 3.5 to 4.5% by weight, .

The major components of the magnesium alloy AZ91D are as follows.

division

Cu
Si
Al
Zn
Fe
Mn
Ni
Sn
Ti
Mg
AZ91D
content
range

0.03
Below
0.1
Below
8.3 ~
9.7
0.35 ~
1.0
0.005
Below
0.15
Below
0.002
Below
0.01
-
Balance

(Unit: wt%)

From the viewpoint of main components, in the AZ91D-based alloy according to the prior art, the content of Mg is 89.3 to 91.35 wt%, whereas in the case of the aluminum alloy for die casting of the present invention, the content of Mg is 0.7 to 1.2 wt% Its content ratio has been remarkably reduced.

On the contrary, in the case of the prior art, the content of Al was about 8.3 to 9.7 wt%, but in the case of the present invention, the content of Al was increased to 4.5 to 5.5 wt% at 0.03 wt% In case of Fe, the content of Fe increased from 0.005 wt% to 0.6 ~ 1.0 wt%, and the content of Ti was 0.15 ~ 0.25 wt%.

The aluminum alloy for die casting of the present invention can improve its mechanical properties by implementing a composition ratio that is significantly different from that of ALDC12 and ADH-5V and AZ91D. Therefore, the tensile strength, yield strength, elastic modulus and maximum load of the alloy can be improved.

Hereinafter, the strength comparison test results of the aluminum alloy for die casting, ALDC12, ADH-5V and AZ91D alloy of the present invention will be described.

The test was carried out according to KS B 0802, and the test room was maintained at a temperature of 20 ± 1 ° C, The humidity was 20 ± 5%.

The test results of the aluminum alloy for die casting of the present invention are shown in Tables 4 and 5 below, and the stress-strain curve reflecting the test results is as shown in FIG. Hereinafter, the aluminum alloy for die casting of the present invention is represented by A7.

Specimen number Width (mm) thickness
(mm) Length
(mm) Maximum load
(kN) The tensile strength
(MPa) #One
5.65 0.65 10.90 1.665 453.430 #2
5.64 0.65 10.95 1.690 460.861 # 3
5.63 0.67 11.29 1.711 453.644 Average
1.688 455.978

Specimen number At break
Strain (%) At maximum load
Strain (%) Modulus of elasticity
(MPa) Yield strength
(MPa) #One
7.634 7.634 18114.944 307.602 #2
7.910 7.910 18410.955 310.409 # 3
7.247 7.203 19420.409 300.595 Average
7.597 7.582 18648.77 306.202

On the other hand, the test results of ADH-5V according to the above test are shown in Tables 6 and 7 below, and the stress-strain curve reflecting the test results is as shown in FIG.

Specimen number Width (mm) thickness
(mm) Length
(mm) Maximum load
(kN) The tensile strength
(MPa) #One
5.61 0.72 10.91 1.441 356.832 #2
5.61 0.72 10.76 1.444 357.383 # 3
5.61 0.69 11.09 1.429 369.198 Average
1.438 361.137

Specimen number At break
Strain (%) At maximum load
Strain (%) Modulus of elasticity
(MPa) Yield strength
(MPa) #One
8.849 8.810 15056.865 256.663 #2
9.750 9.640 14579.305 251.337 # 3
9.413 9.413 14829.694 260.828 Average
9.337 9.287 14821.95 256.276

On the other hand, the test result of ALDC12 according to the above test is as shown in Table 8 and Table 9 below, and the stress-strain curve reflecting the result of ADH-5V is shown in FIG.

Specimen number Width (mm) thickness
(mm) Length
(mm) Maximum load
(kN) The tensile strength
(MPa) #One
5.61 0.73 10.91 1.594 389.266 #2
5.61 0.72 10.95 1.637 405.389 # 3
5.61 0.71 10.78 1.545 387.961 Average
1.592 394.205

Specimen number At break
Strain (%) At maximum load
Strain (%) Modulus of elasticity
(MPa) Yield strength
(MPa) #One
7.055 6.975 15717.779 281.207 #2
7.722 7.698 16129.760 286.402 # 3
6.657 6.567 15767.306 285.118 Average
7.14 7.089 15871.62 284.242

On the other hand, the test results of AZ91D according to the above test are shown in Tables 10 and 11 below, and the stress-strain curve reflecting the test results is as shown in FIG.

Specimen number Width (mm) thickness
(mm) Length
(mm) Maximum load
(kN) The tensile strength
(MPa) #One
5.58 0.68 11.02 1.080 284.589 #2
5.57 0.67 10.88 1.034 277.188 # 3
5.57 0.68 10.89 0.966 255.062 Average
1.020 272.279

Specimen number At break
Strain (%) At maximum load
Strain (%) Modulus of elasticity
(MPa) Yield strength
(MPa) #One
13.754 13.741 9752.219 159.533 #2
12.214 12.072 9447.442 155.187 # 3
8.254 8.086 9576.376 149.147 Average
11.407 11.299 9592.012 154.622

The average maximum load, tensile strength, yield strength, strain and elastic modulus of each alloy shown in Tables 4 to 11 are summarized in Table 12, and a graph for comparing stress-strain curves of the respective alloys at a glance 6.

division
Maximum load
(kN) The tensile strength
(MPa) At maximum load
Strain (%) Modulus of elasticity
(MPa) Yield strength
(MPa) Invention
1.688 455.978 7.582 18648.77 306.202 ADH-5V
1.438 361.137 9.287 14821.95 256.276 ALDC12
1.592 394.205 7.089 15871.62 284.242 AZ91D
1.020 272.279 11.299 9592.012 154.622

As described above, in the case of the aluminum alloy for die casting of the present invention, the maximum load was improved by 17% from ADH-5V, 6% from ALDC12, and 65% from AZ91D.

In terms of tensile strength, ADH-5V was improved by 26%, ALDC12 by 15% and AZ91D by 67%.

On the other hand, the modulus of elasticity was improved by 25% from ADH-5V, 17% from ALDC12 and 94% from AZ91D.

In terms of yield strength, ADH-5V was improved by 19%, ALDC12 by 7% and AZ91D by 98%.

Therefore, the present invention can achieve a remarkable improvement in the mechanical strength by changing the chemical composition ratio of the conventional alloy.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (11)

Wherein the aluminum alloy is inevitably contained in an amount of 0.7 to 1.2% by weight of Mg, not more than 5.5% by weight of Cu, not more than 4.5% by weight of Zn, not more than 10% by weight of Si and the balance of Al and other components. The method according to claim 1,
Wherein the Cu is contained in an amount of 4.5 to 5.5% by weight. The method according to claim 1,
Wherein the Zn is contained in an amount of 3.5 to 4.5% by weight. The method according to claim 1,
And the Si is further contained in an amount of 8.0 to 10.0% by weight. The aluminum alloy for die casting 5. The method according to any one of claims 1 to 4,
Wherein the aluminum alloy further comprises 0.6 to 1.0% by weight of Fe, 0.2% by weight or less of Mn, 0.1 to 0.3% by weight of Ni, 0.1% by weight or less of Sn and 0.15 to 0.25% by weight of Ti. Dissolving the aluminum material;
Adding an alloy component to the molten aluminum;
Casting a molten aluminum alloy,
Wherein the aluminum alloy component comprises 0.7 to 1.2% by weight of Mg, not more than 5.5% by weight of Cu, not more than 4.5% by weight of Zn, not more than 10.0% by weight of Si, and the balance Al and other components inevitably Method of manufacturing aluminum alloy for die casting. The method according to claim 6,
The temperature at the time of dissolution was maintained at 650 to 750 ° C,
Wherein the temperature during casting is maintained at 600 to 700 占 폚. The method according to claim 6,
Wherein the Cu is contained in an amount of 4.5 to 5.5% by weight based on the total weight of the aluminum alloy. The method according to claim 6,
Wherein the Zn is contained in an amount of 3.5 to 4.5% by weight. The method according to claim 6,
And the Si is further contained in an amount of 8.0 to 10.0% by weight based on the total weight of the aluminum alloy. 11. The method according to any one of claims 6 to 10,
Wherein the aluminum alloy further comprises 0.6 to 1.0% by weight of Fe, 0.2% by weight or less of Mn, 0.1 to 0.3% by weight of Ni, 0.1% by weight or less of Sn and 0.15 to 0.25% by weight of Ti. Gt;

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