JP2001335872A - Low thermal expansion aluminum alloy sheet for electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low thermal expansion aluminum alloy sheet for electronic apparatus small in a thermal expansion coefficient and excellent in drawing formability. SOLUTION: This low thermal expansion aluminum alloy sheet for electronic apparatus has a composition containing, by mass, 9 to 14% Si and further containing one or more kinds selected from the groups consisting of <=2.0% Mg, <=0.8% Fe, <=0.3% Cu, <=1.0% Mn and <=0.5% Zn, and the balance aluminum with inevitable impurities, and in which critical drawing height being subjected to drawing under the conditions of blank diameter: 100 mm, punch diameter: 50 mm, die diameter: 52 mm and blank holding pressure: 51N is >=6 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-thermal-expansion aluminum alloy plate for electronic equipment used as a heat-radiating plate, a heat spreader, a shutter and a cover material for a processing device such as a computer.

[0002]

2. Description of the Related Art In recent years, although the processing capability of personal computers has been significantly improved, on the other hand, an increase in the amount of heat generated has increased the demand for improved heat dissipation. For example, as a structure of a microprocessor, when bonding a die and a heat sink, heat and pressure are applied with an adhesive or a compound interposed therebetween, but when the heat sink has a large thermal deformation, a non-contact portion is eliminated. In addition, a measure is taken to use an adhesive or a compound in an unnecessarily large amount as a buffering agent to prevent a decrease in heat radiation. Further, if the material strength at high temperatures is too low, deformation may occur due to the pressing force.

In general, aluminum or copper has been used as a material for heat dissipation. Recently, however, aluminum alloys having high heat conductivity and excellent heat dissipation have been widely used.
As for the type, JIS 1100 or 5
052 etc. are mainly used. Further, such a heat sink and a heat spreader are manufactured by cutting, but in order to further improve the material yield and reduce cost, they are manufactured by press drawing.
Good draw formability is required.

However, since the aluminum alloy has a high coefficient of thermal expansion and therefore a large amount of deformation, it is necessary to use a large amount of a buffer such as the above-mentioned adhesive, thereby increasing the material cost.

Conventionally, as aluminum alloys having a low coefficient of thermal expansion, those disclosed in Japanese Patent Publication No. 3-55535 and Japanese Patent Publication No. 4-80108 are known.

[0006]

However, the aluminum alloys described in Japanese Patent Publication Nos. 3-55535 and 4-80108 attempt to improve mechanical properties such as low thermal expansion and wear resistance. However, there is a problem that draw formability is insufficient. Thus, conventionally, as an aluminum alloy plate for electronic devices,
There is no one having sufficient draw formability.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a low-thermal-expansion aluminum alloy sheet for electronic devices having a small coefficient of thermal expansion and excellent drawability.

[0008]

The low thermal expansion aluminum alloy sheet for electronic equipment according to the present invention contains Si: 9 to 14% by mass, further contains Mg: 2.0% by mass or less, and Fe: 0.
8 mass% or less, Cu: 0.3 mass% or less, Mn: 1.0
1% or less selected from the group consisting of 0.5% by weight or less and Zn: 0.5% by weight or less, the balance being composed of aluminum and inevitable impurities, blank diameter: 100 mm, punch diameter : 50 mm, die diameter: 52
mm, wrinkle control: the limit drawing height when drawing is performed under the condition of 51 N is 6 mm or more.

A method for producing a low thermal expansion aluminum alloy sheet for electronic equipment according to the present invention comprises: Si: 9 to 14% by mass; Mg: 2.0% by mass or less; Fe: 0.8% by mass or less; Cu: 0.3% by mass or less, Mn: 1.0% by mass
And Zn: an aluminum alloy ingot containing one or more selected from the group consisting of 0.5% by mass or less, with the balance being aluminum and unavoidable impurities, at a temperature of 450 to 530 ° C. And a step of performing hot rolling at a working rate of 75% or more and cold rolling at a working rate of 35% or more.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In order to solve the above-described problems, the inventors of the present invention have conducted intensive experiments and researches.As a result, the amount of Si contained in the aluminum alloy is controlled within a predetermined range to control the coefficient of thermal expansion to be low,
It has been found that by adding Fe, Cu, Mn, Zn, Mg and the like as needed, draw formability can be maintained and strength can be improved. In addition, it has been found that by appropriately controlling the homogenizing heat treatment temperature of the aluminum alloy and the working ratio during hot rolling and cold rolling, excellent draw formability can be obtained.

The reasons for limiting the numerical value of the low thermal expansion aluminum alloy sheet for electronic equipment of the present invention will be described below.

Si content: 9 to 14% by mass Si has an effect of lowering the coefficient of thermal expansion. If the content is less than 9% by mass, the effect cannot be sufficiently obtained. Cracks occur at the time, and the productivity is remarkably deteriorated, and the moldability is lowered. Therefore, Si
The content is 9 to 14% by mass.

The present invention may contain one or more of the following elements depending on the required characteristics of the product to which the invention is applied.

Mg: 2.0% by mass or less Mg has the effect of increasing the strength of the matrix and improving the mechanical properties and machinability at high temperatures. However, 2% by mass
Exceeds, the drawability is significantly reduced.
Is 2% by mass or less.

Fe: 0.8% by mass or less, Cu: 0.3 quality
% Or less, Mn: 1.0% by mass or less, Zn: 0.5% by mass
% Or less Fe, Cu, Mn, and Zn, like Mg, are all effective in improving mechanical properties and machinability.
It is necessary to add each according to the required characteristics of the product. If the content exceeds the upper limit, coarse crystals are purified and the drawability is reduced. Therefore, its content is
Fe: 0.8% by mass or less, Cu: 0.3% by mass or less, Mn: 1.0% by mass or less, and Zn: 0.5% by mass or less, respectively.

Next, a method for producing a low thermal expansion aluminum alloy sheet for electronic equipment according to the present invention will be described. First, the aluminum alloy ingot having the above composition is subjected to a homogenizing heat treatment. The homogenization heat treatment makes the micro-segregation of the ingot uniform and increases the ductility by spheroidizing the eutectic Si particles, thereby improving the rollability and the drawability. Here, if the homogenizing heat treatment temperature is lower than 450 ° C., the effect is not sufficient, and if it exceeds 520 ° C., local melting occurs. Therefore, the homogenizing heat treatment temperature is set to 450 to 530 ° C. The time of the homogenizing heat treatment can be appropriately selected within a range of about 3 to 24 hours.

Next, hot rolling and cold rolling are performed. Hot working and cold working are performed to cut and refine the eutectic Si particles, refine the structure after final annealing, and improve the formability. Improve. However, if the hot working ratio is less than 75% and the cold working ratio is less than 35%, the effect is not exhibited. Therefore, the hot working ratio and the cold working ratio are 75% or more and 3%, respectively.
5% or more.

Thereafter, depending on the required characteristics of the product,
Final annealing may be performed. In particular, when draw formability is required, it is effective to perform final annealing under the following conditions. That is, heating is performed at a temperature of 350 to 450 ° C. for 0.5 hour or more, and cooling is performed at a cooling rate of 100 ° C./hour or less.

By manufacturing as described above, the blank has a low thermal expansion, a blank diameter of 100 mm, and a punch diameter of 50.
mm, die diameter: 52 mm, and wrinkle holding: 51 N. The aluminum alloy sheet having excellent draw formability with a limit drawing height of 6 mm or more when subjected to drawing processing can be obtained.

[0020]

EXAMPLES Hereinafter, a low thermal expansion aluminum alloy sheet for electronic equipment of the present invention will be actually manufactured, and its effect will be described in comparison with a comparative example out of the scope of the present invention.

First Example An aluminum alloy having the composition shown in Table 1 below was cast into an ingot according to a conventional method, and subjected to a homogenizing heat treatment at a temperature of 510 ° C. for 4 hours. After the thickness was reduced to 0.8 mm by cold rolling at a working ratio of 73%, final annealing was performed at a temperature of 360 ° C. Table 2 below shows the results of measurement of the average linear thermal expansion coefficient, 0.2% proof stress, and draw formability of this aluminum alloy sheet. Average coefficient of linear thermal expansion is 40 to 90
The linear thermal expansion coefficient at a temperature of ° C. was measured, and the average value was determined. In addition, the limit drawing height is a blank diameter of 100 mm,
Punch diameter 50 mm, die diameter 52 mm, wrinkle holder: 5
The draw height at 1 N was measured. Rust-preventing oil for copper plates was used as lubricating oil.

A specimen having a 0.2% proof stress of 45 N / mm ² or more was regarded as good, and a specimen having a 0.2% proof stress less than 45 N / mm ² was regarded as defective. Further, those having an average linear expansion coefficient of 21 / ° C. or less were evaluated as good, and those having an average linear expansion coefficient exceeding 21 / ° C. were evaluated as poor. Further, those having a limit drawing height of 6 mm or more were evaluated as good, and those having a limit drawing height of less than 6 mm were evaluated as defective.

[0023]

[Table 1]

[0024]

[Table 2]

Examples 1 to 15 show that the aluminum alloy composition and the limit drawing height are within the range of the present invention, that they have excellent draw formability and that the average linear expansion coefficient is small.
Even in the case where mechanical properties are required, as shown in the examples, sufficient drawability could be obtained within the scope of the present invention.

In Comparative Examples 16 to 23, since the composition of any of Si, Fe, Cu, Mn, Mg, and Zn contained in the aluminum alloy was out of the range of the present invention, the critical narrowing height was less than 6 m, and the results were excellent. Drawability could not be obtained.

Example 2 An aluminum alloy ingot having the same chemical composition as Example 10 in Table 1 was subjected to a homogenizing heat treatment under the conditions shown in Table 3 below.
After hot rolling and cold rolling to a sheet thickness of 0.8 mm,
The final annealing was performed at a temperature of 360 ° C. to produce an aluminum alloy plate. Then, the average linear thermal expansion coefficient, 0.2% proof stress, and critical drawing height were measured under the same conditions as in the first example. The results are shown in Table 4 below.

[0028]

[Table 3]

[0029]

[Table 4]

In Examples 24 to 28, since the homogenizing heat treatment temperature and the working ratio of hot rolling and cold rolling were within the range of the present invention, both the average linear expansion coefficient and the drawability were good. Further, even when mechanical properties were required, as shown in the examples, sufficient drawability could be obtained within the scope of the present invention.

In Comparative Examples 29 to 31, since the homogenizing heat treatment temperature was lower than the lower limit of the range of the present invention, or the working ratio of hot rolling or cold rolling was out of the range of the present invention, the desired draw formability was obtained. I couldn't. Further, in Comparative Example 32, since the homogenizing heat treatment temperature exceeded the range of the present invention, burning occurred, cracking occurred during hot rolling, and a product could not be produced.

[0032]

As described in detail above, according to the present invention,
By appropriately defining the chemical composition of the aluminum alloy and the temperature, hot working rate and cold working rate of the homogenizing heat treatment, the necessary mechanical strength can be obtained, the coefficient of thermal expansion is low, and excellent draw formability can be obtained. Obtainable.

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Claims (2)

[Claims] 1. An alloy containing 9 to 14% by mass of Si, 2.0% by mass or less of Mg, 0.8% by mass or less of Fe,
u: 0.3% by mass or less, Mn: 1.0% by mass or less, and Z
n: one or more selected from the group consisting of 0.5% by mass or less, the balance having a composition consisting of aluminum and unavoidable impurities, a blank diameter of 100 mm,
A low-thermal-expansion aluminum alloy plate for electronic equipment, wherein a limit drawing height when drawing is performed under the conditions of a punch diameter: 50 mm, a die diameter: 52 mm, and a blank holder: 51 N is 6 mm or more. 2. It contains 9 to 14% by mass of Si, further contains 2.0% by mass or less of Mg, 0.8% by mass or less of Fe,
u: 0.3% by mass or less, Mn: 1.0% by mass or less, and Z
n: an aluminum alloy ingot containing one or more selected from the group consisting of 0.5% by mass or less and having a balance of aluminum and unavoidable impurities,
Performing a homogenizing heat treatment at a temperature of 50 to 530 ° C .;
Hot rolling at a working rate of 75% or more, and cold rolling at a working rate of 35% or more. A method for producing a low thermal expansion aluminum alloy sheet for electronic equipment, comprising: