JP2002226932A - Aluminum alloy for heat sink having excellent strength and thermal conductivity and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy which has strength enough for withstanding machining for a heat sink, high heat radiability and thermal conductivity, and to provide a production method therefor. SOLUTION: The aluminum alloy material for a heat sink has a composition containing, by weight, 0.40 to 1.60% Si, 0.30 to 0.70% Mg, 0.20 to 1.00% Fe and 0.002 to 0.08% B, and the balance aluminum with inevitable impurities. The aluminum alloy material has electric conductivity of >=48IACS% and a Brinell hardness value of >=50. In the production method for the aluminum alloy material for a heat sink, the alloy having the above composition is cast by diecasting, and is thereafter subjected to aging heat treatment at 190 to 260 deg.C for 0.8 to 5.0 hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy material having excellent strength and thermal conductivity, and more particularly to an aluminum alloy material useful as a material for a heat sink which is a heat radiating component of an electronic device such as a semiconductor. It is about materials.

[0002]

2. Description of the Related Art Aluminum alloys are used in various fields based on their properties because they are lightweight, and at the same time, have excellent electrical and thermal conductivity. 2. Description of the Related Art In recent years, the performance of electronic devices has been improved, and heat sinks, which are heat dissipating components of electronic devices such as semiconductors, are required to have high heat dissipation efficiency.
Further, for example, in the case of a heat sink component that requires cutting such as screw hole processing, high material strength as well as heat radiation efficiency are required. The heat sink is mainly manufactured by die casting, and as a kind of alloy, ADC1 or ADC12 of a JIS alloy for die casting is generally used. However, these alloys have sufficient strength to withstand cutting, but have poor thermal conductivity,
It is insufficient as a material for a heat sink that requires high heat radiation efficiency.

On the other hand, when the amount of a metal that affects thermal conductivity, for example, Si, among the metals added to the aluminum alloy to secure thermal conductivity is reduced, the material strength itself decreases, For example, there is a problem in cutting work such as crushing of a screw thread at a portion where a screw hole is formed. Therefore,
There is an increasing demand for aluminum alloy materials for heat sinks that have excellent thermal conductivity and also have high strength processing characteristics.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aluminum alloy material for a heat sink which has particularly high heat conductivity and which has a strength capable of withstanding cutting work while maintaining particularly high heat conductivity. To provide. Here, particularly high thermal conductivity means a thermal conductivity of 180 W / m · ° C. or more, which is 4
This corresponds to 8 IACS% or more.

[0005]

Means for Solving the Problems The present inventors have developed an alloy material for a heat sink that requires particularly high heat dissipation.
As a result of various studies on the elements added to the aluminum alloy and the conditions of the aging heat treatment after casting, while maintaining the thermal conductivity and ensuring the strength that can withstand the cutting process, a predetermined amount of Si, The present inventors have found that it is useful to perform a predetermined aging heat treatment on an alloy to which Mg, Fe, and B are added, and have reached the present invention. That is, the gist of the present invention is: Si 0.40 to 1.60 wt%, Mg 0.30
0.70 wt%, Fe 0.20-1.00 wt%, B
0.002 to 0.08 wt%, the balance being aluminum and unavoidable impurities, and having a conductivity of 48 IA
An aluminum alloy material for a heat sink having a CS% or more and a Brinell hardness value of 50 or more.

Another gist of the present invention is that Si 0.40 to 1.
60 wt%, Mg 0.30 to 0.70 wt%, Fe0.
20-1.00wt%, B0.002-0.08wt%
After casting by die-casting, an aluminum alloy containing aluminum and inevitable impurities
The above-mentioned method for producing an aluminum alloy material for a heat sink, which is subjected to an aging heat treatment at a temperature range of 0 to 260 ° C. for a time range of 0.8 to 5.0 hours, and is produced using these aluminum alloy materials for a heat sink. Heat sink.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum alloy material of the present invention
An object of the present invention is to manufacture a heat sink having high thermal conductivity and strength enough to withstand cutting processing among heat sinks manufactured by die casting. That is, this alloy material has a high thermal conductivity of 48 IACS% in electrical conductivity.
The above (corresponding to a thermal conductivity of 180 W / m · ° C. or more), preferably 48 to 52 IACS%, and a Brinell hardness value of 50 or more, preferably 50 to 65, as a strength that can withstand cutting. It is intended for security. Incidentally, the thermal conductivity and the electrical conductivity are in a proportional relationship, and generally, as an evaluation method of the thermal conductivity, the electrical conductivity is used as an index, so also in the present invention, the measured value of the electrical conductivity as an index of the thermal conductivity. It will be described.

[0008] By simultaneously adding Si and Mg to the aluminum alloy material of the present invention, the strength of the alloy can be increased without greatly lowering the conductivity, and particularly, aging after die casting. The heat treatment can greatly improve the strength. The addition amount of Si is 0.40 to 1.60 wt%, preferably 0.1 to 1.0 wt%.
It is appropriately selected in the range of 70 to 1.30 wt%. If the addition amount is less than 0.40 wt%, the strength is insufficient, and on the other hand, 1.60.
Exceeding wt% is undesirable because it causes a decrease in conductivity. The addition amount of Mg is appropriately selected in the range of 0.30 to 0.70 wt%, preferably 0.40 to 0.60 wt%. If the amount is less than 0.30 wt%, the strength is insufficient.
On the other hand, if it is added in a large amount exceeding 0.70 wt%, in addition to a decrease in conductivity, a decrease in the fluidity of the molten metal during die casting due to excessive Mg cannot be ignored.

Fe is added to prevent seizure between the aluminum alloy and the mold, as is also added to the conventional JIS alloy for die casting. 0.20
If it is less than wt%, the effect of preventing seizure is not sufficient, and if it is added in excess of 1.00 wt%, the effect is the same as that of 1.00 wt% or less, and only the thermal conductivity is reduced. . Therefore, the added amount of Fe is 0.2
0 to 1.00 wt%, preferably 0.30 to 0.70 w
It is appropriately selected within the range of t%.

B added to the alloy material of the present invention has the effect of improving the electrical conductivity of the Al-Si-Mg-Fe alloy by its addition. The added amount is 0.002-0.08
wt%, preferably 0.005 to 0.03 wt%. If the addition amount is less than 0.002 wt%, the effect of improving thermal conductivity is not sufficiently achieved, while if it exceeds 0.08 wt%, B
Becomes excessive, and conversely, the effect of improving the thermal conductivity is reduced.

By subjecting the aluminum alloy material of the present invention to aging heat treatment after die casting, its thermal conductivity and strength can be simultaneously improved. The temperature range for the aging heat treatment is 190-260 ° C, preferably 200-2 ° C.
It is appropriately selected within the range of 45 ° C. If the temperature is lower than 190 ° C., a long-time heat treatment is required to improve the strength, and the productivity is deteriorated, which is not practical. On the other hand, when the temperature exceeds 260 ° C., overaging occurs and the strength is reduced. The aging heat treatment time is
It is appropriately selected within a range of 0.8 to 5.0 hours, preferably 1.0 to 4.0 hours. If the time is less than 0.8 hours, the strength is not sufficiently improved. On the other hand, if the time exceeds 5.0 hours, not only will overaging occur, resulting in a decrease in strength but also a decrease in productivity.

The aluminum alloy of the present invention contains unavoidable impurities in addition to the above-mentioned alloy components. If necessary, a component added for improving other properties, for example, for improving corrosion resistance, may be added to the alloy of the present invention. May be included in a range that does not impair the characteristics of the conductivity and the Brinell hardness that are essential.
Such components include, for example, Cu, Zn, Ni,
Co, Mn, Zr, Cr, Ti, Sn, In, Ca, S
r, Na, etc., but if these components are added excessively, the thermal conductivity may be reduced. Therefore, Ni and Co are 0.60 wt% or less, and other elements are 0.20 wt% or less. It is necessary to.

The aluminum alloy of the present invention has higher thermal conductivity than conventional JIS alloys for die casting.
And since it maintains high strength, it can be used as a heat sink material that requires high heat radiation characteristics and strength to withstand cutting.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. In the following examples, the thermal conductivity was evaluated by measuring the electrical conductivity (IACS%) of the alloy because the thermal conductivity is in proportion to the electrical conductivity.

Example 1 and Comparative Examples Alloys having the respective compositions shown in Tables 1 and 2 below were cast by die casting, and the conductivity and Brinell hardness of the ingot were measured and evaluated. For the alloys in Table 1, after casting and 225
The evaluation was performed after aging heat treatment under the condition of ° C × 2 hours. 99.8 w purity as aluminum for alloy preparation
t% was used. As is clear from the results in Table 1,
In the composition range of the example of the present invention, after the aging heat treatment, a conductivity of 48 IACS% or more and a Brinell hardness value of 50 or more are achieved. Further, in the Al-Si-Mg-Fe-based alloy, even if the alloy (No. 15) has the conductivity and the Brinell hardness value specified in the present invention, the addition of B in a predetermined range allows the same composition to be obtained. This shows that the conductivity of the alloy can be further increased as compared with the case where no alloy is added. In addition, the alloy No. 12 satisfies the specified values of the present invention with respect to the electrical conductivity and the Brinell hardness, but has a disadvantage that castability (melt flowability) at the time of die casting is inferior due to an increase in Mg. Conventional die-casting alloys (ADC1
And ADC12) have significantly lower conductivity than the invention examples. Further, even if the amount of Si added is adjusted to increase the electrical conductivity, for example, the electrical conductivity and the hardness cannot be simultaneously increased to the extent that the alloy of the present invention reaches.

[0016]

[Table 1]

[0017]

[Table 2]

Example 2 Alloy No. 1 shown in Table 1 was used. 2 [Composition (wt%): Si1.00, M
g0.50, Fe0.50, B0.01], and the alloy was evaluated for electrical conductivity and Brinell hardness after casting and after aging heat treatment under the conditions shown in Table 3. Table 3 shows the results. In order to obtain good values for both conductivity and hardness, aging conditions in the range of the invention examples are preferable.

[0019]

[Table 3]

[0020]

By using the aluminum alloy of the present invention, a good heat sink having both high thermal conductivity and high strength can be provided, so that the industrial value is extremely large.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C22F 1/00 650 C22F 1/00 650F 651 651A 661 661A 682 682 691 691B 691C

Claims (4)

[Claims] 1. 0.40 to 1.60 wt% of Si, Mg
0.30 to 0.70 wt%, Fe 0.20 to 1.00 w
Aluminum for heat sinks, containing at least t% and 0.002 to 0.08 wt% of B, the balance being aluminum and unavoidable impurities, having a conductivity of 48 IACS% or more, and a Brinell hardness value of 50 or more. Alloy material. 2. 0.40 to 1.60 wt% of Si, Mg
0.30 to 0.70 wt%, Fe 0.20 to 1.00 w
An aluminum alloy containing 0.002 to 0.08% by weight of B and the balance of aluminum and unavoidable impurities is cast by die casting and then in a temperature range of 190 to 260 ° C. for a time of 0.8 to 5.0 hours. The aluminum alloy material for a heat sink according to claim 1, wherein the aluminum alloy material is manufactured by aging heat treatment in a range. 3. 0.40 to 1.60 wt% of Si, Mg
0.30 to 0.70 wt%, Fe 0.20 to 1.00 w
An aluminum alloy containing 0.002 to 0.08% by weight of B and the balance of aluminum and unavoidable impurities is cast by die casting and then in a temperature range of 190 to 260 ° C. for a time of 0.8 to 5.0 hours. The method for producing an aluminum alloy material for a heat sink according to claim 1, wherein aging heat treatment is performed within a range. 4. A heat sink manufactured using the aluminum alloy material for a heat sink according to claim 2.