JPH1112797A - Aluminum-made heat radiating plate and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat radiating plate for semi-conductor device having high adhesion with a synthetic resin for sealing without developing the crack and lowering the heat radiating property by applying an anodic-oxidized film having a specific sealing degree value on an aluminum or aluminum alloy plate. SOLUTION: The anodic-oxidizing treatment is executed to the aluminum or aluminum alloy plate by using sulfuric acid acidic bath, etc., to improve the corrosion resistance and decolativeness on the surface. A sealing treatment is applied to the anodic-oxidized film formed by the above treatment by using boiled water bath dissolving a sealing assist agent of metallic salt, etc., and the sealing degree value of the anodic-oxidized film is regulated to >=80 mg/dm<2> . Further, if necessary, a dipping treatment to the plate is executed in nitric acid of about 30% concn. at about 20 deg.C for about 45 sec and then, the enlargement of fine hole in the anodic-oxidizing film and the recovery of surface activation can be contrived. After this sealing treatment, a heat treatment is executed at >=180 deg.C to the anodic-oxidized film. By this method, the aluminum or aluminum alloy-made heat radiating plate having high adhesion with the synthetic resin for sealing the semi-conductor device and excellent heat radiation, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiator plate made of aluminum or an aluminum alloy, and more particularly to a radiator plate made of aluminum or an aluminum alloy mounted on a resin-sealed semiconductor device (plastic package) having a semiconductor element mounted thereon.

[0002]

2. Description of the Related Art A semiconductor device equipped with an integrated circuit is compatible with the miniaturization and high performance of electronic equipment. Packages of various structures have been proposed. In particular, in a plastic package type semiconductor device sealed with a resin widely used, a heat radiating plate is provided to cope with an increase in heat generation. In order to improve the heat radiation characteristics, copper and aluminum having high thermal conductivity are used as the material of the heat radiation plate. Among them, aluminum or aluminum alloy (hereinafter, also simply referred to as aluminum) is widely used because of its light weight and the like. The radiator plate is molded into the resin and exposes part of the radiator plate to the outside of the resin to release the heat to the circuit board or the atmosphere in order to improve the heat release to the outside. Anodizing treatment is performed from the viewpoint of enhancing the corrosion resistance of the surface of aluminum or its alloy or from the viewpoint of cosmetics.

When a heat radiating plate made of aluminum or an aluminum alloy is sealed with a resin, if a gap is formed between the heat radiating plate and the aluminum or its alloy or if the adhesiveness is insufficient, the heat radiating property is significantly reduced. In addition, if a gap is formed, a crack in the sealing resin is induced when the temperature rises due to heat generation, so that high adhesion is required between the heat sink and the resin.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the adhesion of a heat sink made of aluminum or an aluminum alloy to a synthetic resin used for sealing a semiconductor device. It is an object of the present invention to provide an aluminum heat radiating plate that enhances the adhesion between the heat sink and a synthetic resin, and does not cause cracks at the interface between the sealing synthetic resin and the heat radiating plate and does not cause a decrease in heat radiation. .

[0005]

SUMMARY OF THE INVENTION The present invention relates to a heat sink made of aluminum or aluminum alloy, wherein the anodic oxide coating applied to the heat sink has a sealing value of 80 mg / dm ² or more. It is. Further, in the method for producing a heat sink made of aluminum or aluminum alloy, after the anodizing treatment, the anodized film is sealed so as to have a sealing degree value of 80 mg / dm ² or more, and then heat-treated at 180 ° C. or more. Or a method of manufacturing an aluminum alloy radiator plate.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An oxide film formed by anodic oxidation for the purpose of improving the corrosion resistance of aluminum or an aluminum alloy has fine pores. Micropores are useful for coloring by coloring etc., and for imparting functionality,
On the other hand, there is a problem that the film surface has a large adsorptivity, is easily contaminated, and lowers corrosion resistance. Therefore, sealing treatment is performed for the purpose of closing the micropores formed in the film and improving corrosion resistance, such as boiling treatment in boiling water, treatment in an aqueous solution of nickel acetate, chromate, or the like. ing.

[0007] By performing the sealing treatment, aluminum or an aluminum alloy can have excellent characteristics such as corrosion resistance. However, if the heat-dissipating plate subjected to the sealing treatment is used for a resin-sealed package, the aluminum or aluminum alloy can be sealed. It became clear that the adhesion to the sealing resin was lower than that in which no hole treatment was performed.

Therefore, the present inventors have conducted intensive studies on the heat-dissipating plate which has been subjected to the sealing treatment, and as a result, have found that the degree of sealing affects the adhesion. That is,
The degree of sealing measured by the chromic phosphate method is 80 mg /
When it is larger than dm ² , the adhesiveness is excellent,
It has been found that a plastic package free of cracks can be obtained.

The heat radiating plate of the present invention is not limited to a case in which aluminum or an aluminum alloy machined into an individual heat radiating plate is processed, but a large number of heat radiating plates are cut from a long member such as aluminum or an aluminum alloy. In the case of manufacturing by cutting, the member before cutting may be processed by the method of the present invention and then cut into a predetermined size. In this case, the cut surface is molded without performing the treatment of the present invention, but since the cut surface is the end surface of the plate-shaped member, the cut surface is very small compared to the area to be molded of the heat sink. It does not adversely affect the adhesion to the resin to be molded.

In the present invention, the measurement of the sealing degree by the chromic acid phosphate method is carried out by measuring 35 ml / l phosphoric acid and 20 g / chromic acid.
1 was immersed in an aqueous solution at 38 ° C. for 15 minutes, and the weight loss was measured (ARS-2321 standard for aluminum surface treatment research association). In the case of aluminum building materials used outdoors where the corrosive environment is severe, it is preferable that the value of the degree of sealing by the chromic acid phosphate method is 20 mg / dm ² or less, and that the sealing treatment is completely performed. Have been. However, with such a degree of sealing, sufficient adhesion with the molded resin cannot be obtained, and the sealing degree is 80 mg.
At / dm ² or less, the occurrence of cracks in the plastic package was inevitable.

The heat-radiating plate of the present invention can be sealed by using a bath in which water in which a metal salt or a fluorinated sealing aid is dissolved is boiled. Specifically, nickel acetate 5 g / l, borane A bath of 5 g / l of acid can be used. The anodic oxidation treatment of the heat sink of the present invention is preferably performed using an acid bath such as sulfuric acid, oxalic acid, other organic acids and their mixed acids. For example, 130 to 180 g / l sulfuric acid and 1 to 10 g
Baths containing g / l of an aluminum component can be mentioned.

Further, the heat sink of the present invention can be further improved in adhesion by immersing it in nitric acid before and / or after the sealing treatment. When immersed in nitric acid before the sealing treatment, not only increases the sealing degree value, but also enlarges the pores of the anodic oxide film,
As a result, pores that cannot be completely filled by the sealing treatment are generated. In addition, the immersion treatment after sealing can partially dissolve the sealing surface, recover the surface activity, and generate irregularities. These treatments improve the adhesion between the heat sink and the resin of the plastic package. can do. For example, when the treatment is performed by immersing in nitric acid, a concentration of 3
After immersion in 0% by weight of nitric acid at a temperature of 20 ° C. for 45 seconds, it is preferable to wash and dry with water.

[0013]

The present invention will be described in more detail with reference to the following examples. Example 1 A 1.5 mm-thick Al-2% Fe alloy was cut into 24 mm squares, and stepped by press working to obtain test pieces.
A bath temperature of 15 ° C. in a 6% by weight sulfuric acid bath with a lead electrode as a counter electrode,
Anodizing treatment was performed at a current density of 2 A / dm ² and a conduction time of 38 minutes to form a film having a thickness of 25 μm. Next, 5 g / l of nickel acetate and 6 g / l of boric acid were dissolved in water, and a nickel salt-based sealing aid whose pH was adjusted to 5 to 6 by adding acetic acid and sodium hydroxide was added. 5 in the water
Sealed for minutes. The film color was dark gray. The test piece after the sealing treatment was treated with phosphoric acid 35 ml / l and chromic acid 20 g /
The resultant was immersed in an aqueous solution (38 ° C.) containing 1 for 7 minutes, and the weight loss was measured. The decrease was 180 mg / dm ² . Next, this test piece was molded using an epoxy resin (MP-190M manufactured by Nitto Denko Corporation) to produce a mold test piece. The mold test piece was heated to 300 ° C. to perform a crack generation test. There were no cracked mold test pieces among the 20 tested.

Example 2 An Al-2% Fe alloy having a thickness of 1.5 mm was cut into 24 mm squares, and stepped by press working to obtain test pieces.
A bath temperature of 15 ° C. in a 6% by weight sulfuric acid bath with a lead electrode as a counter electrode,
Anodizing treatment was performed at a current density of 1.5 A / dm ² and a conduction time of 30 minutes to form a film having a thickness of 15 μm. Next, 5 g / l of nickel acetate and 6 g / l of boric acid were dissolved in water, and a nickel salt-based sealing aid whose pH was adjusted to 5 to 6 by adding acetic acid and sodium hydroxide was added at 75 ° C. Sealing treatment was performed in water for 20 minutes. The film color was dark gray.
The test piece after the sealing treatment was treated with phosphoric acid 35 ml / l and chromic acid 2
It was immersed in an aqueous solution (38 ° C.) containing 0 g / l for 15 minutes, and the weight loss was measured. The amount of reduction is 130 mg / dm ²
Met. Next, this test piece was molded using an epoxy resin (MP-190M manufactured by Nitto Denko Corporation) to produce a mold test piece. The mold test piece was heated to 300 ° C. to perform a crack generation test. There were no cracked mold test pieces among the 20 tested.

Example 3 An Al-2% Fe-0.5% Mn alloy having a thickness of 0.8 mm was formed into a circular shape having a diameter of 22 mm by press working, and further stepped by press working to obtain a test piece. Later, concentration 1
In a 6% by weight sulfuric acid bath, with a lead electrode as a counter electrode, a bath temperature of 10 ° C.,
Anodizing treatment was performed under the conditions of a current density of 1.5 A / dm ² and an energizing time of 30 minutes to form a 15 μm film. Next, sealing treatment was performed for 10 minutes at 100 ° C. in an aqueous solution in which sodium pyrophosphate was dissolved to a concentration of 80 ppm. The test piece after the sealing treatment was immersed in an aqueous solution containing 35 ml / l of phosphoric acid and 20 g / l of chromic acid at a temperature of 38 ° C for 15 minutes, and the weight loss was measured. Reduction is 125
mg / dm ² . The obtained test piece after sealing was molded using an epoxy resin (MP-7400 manufactured by Nitto Denko Corporation) to obtain a mold test piece. 30 mold test pieces
A crack generation test was performed by heating to 0 ° C. There were no cracked mold test pieces among the 20 tested.

Example 4 A6061 alloy having a thickness of 0.5 mm was cut into a 28 mm square, and stepped by press working to form a test piece. In a 18% by weight sulfuric acid bath, a lead electrode was used as a counter electrode, and the bath temperature was changed. 18
Anodizing was carried out at a temperature of 2 ° C., a current density of 2 A / dm ² , and an energizing time of 45 minutes to form a 30 μm film. Next, sealing treatment was performed at 100 ° C. for 10 minutes in water to which phosphoric acid was added to a concentration of 45 ppm.
The film color was dark gray. After the sealing treatment, the test piece was treated with an aqueous solution containing phosphoric acid 35 ml / l and chromic acid 20 g / l (3
8 ° C.) for 15 minutes, and the weight loss was measured.
The decrease was 150 mg / dm ² . Then, it was molded using an epoxy resin (MP-7400 manufactured by Nitto Denko Corporation) to obtain a molded test piece. 30 mold test pieces
A crack generation test was performed by heating to 0 ° C. There were no cracked mold test pieces among the 20 tested.

Example 5 An Al-2% Fe alloy having a thickness of 1.5 mm was cut into a square of 24 mm, stepped by pressing to form a test piece, and a lead electrode was placed in a 16% by weight sulfuric acid bath. As a counter electrode, anodizing treatment was performed under the conditions of a bath temperature of 15 ° C., a current density of 2 A / dm ² , and a conduction time of 38 minutes to form a 25 μm film. 9
It was boiled in water at 0 ° C. for 10 minutes to perform a sealing treatment. The test piece after the sealing treatment was immersed in an aqueous solution (38 ° C.) containing phosphoric acid 35 ml / l and chromic acid 20 g / l for 7 minutes,
The weight loss was measured. 250 mg / dm reduction
^{Was 2} . This test piece was molded using an epoxy resin (MP-190M manufactured by Nitto Denko Corporation) to obtain a molded test piece. The mold test piece was heated to 300 ° C. to perform a crack generation test. None of the 20 tested had cracks.

Example 6 A 1.5 mm-thick Al-2% Fe alloy was cut into 24 mm squares, stepped by press working to form test pieces, and a lead electrode was placed in a 18% by weight sulfuric acid bath. As a counter electrode, anodizing was performed under the conditions of a bath temperature of 15 ° C., a current density of 2 A / dm ² , and an energization time of 45 minutes to form a 30 μm-thick film. Next, sealing treatment was performed for 10 minutes in a 100 ° C. aqueous solution containing 45 ppm of phosphoric acid. The resulting coating was dark gray. The test piece after the sealing treatment was treated with
and 20 g / l of chromic acid were immersed in an aqueous solution (38 ° C.) for 7 minutes, and the weight loss was measured. 150 reduction
mg / dm ² . Next, heat treatment was performed at 225 ° C. for 5 minutes using a circulating hot air drying furnace. Next, this test piece was epoxy resin (MP-7400 manufactured by Nitto Denko Corporation).
Was used to mold a test piece. The mold test piece was heated to 300 ° C. to perform a crack generation test. There were no cracked mold test pieces among the 20 tested.

Comparative Example 1 A6061 alloy having a thickness of 1.5 mm was cut into a square of 24 mm, stepped by press working to form a test piece, and in a 16% by weight sulfuric acid bath, a lead electrode was used as a counter electrode, and a bath temperature was set. Fifteen
A 10 μm film was formed by anodizing at 30 ° C. and a current density of 1.2 A / dm ² for 30 minutes. Subsequently, a dye for alumite (DeepBlackMLW manufactured by Sando Co., Ltd.) was added to 6
Staining was performed for 5 minutes in a staining solution in which g / l had been dissolved. Further, in order to stabilize the dye and perform the sealing treatment, the mixture was boiled for 30 minutes in pure water to which the same nickel salt sealing aid as in Example 1 was added. The coating color was true black. The test piece after the sealing treatment was immersed in an aqueous solution (38 ° C.) containing 35 ml / l of phosphoric acid and 20 g / l of chromic acid for 15 minutes, and the weight loss was measured. The decrease was 6 mg / dm ² . Next, this test piece was epoxy resin (MD-190M manufactured by Nitto Denko Corporation).
, And heated to 300 ° C. to conduct a crack generation test. Cracks occurred in 5 out of 20 tested.

Comparative Example 2 An Al-2% Fe alloy having a thickness of 0.8 mm was formed into a circular shape having a diameter of 22 mm by press working to prepare a test piece, and a lead electrode was used as a counter electrode in a 16% by weight sulfuric acid bath at a bath temperature of 15%. ° C, current density 2
A / dm ² , anodizing treatment for 38 minutes
A film of 5 μm was obtained. The mixture was boiled in pure water at 100 ° C. for 10 minutes. The film color was dark gray. The obtained test piece after the sealing treatment was treated with phosphoric acid 35 ml / l and chromic acid 20 g / l.
The solution was immersed in 1 l of an aqueous solution (38 ° C.) for 15 minutes, and the weight loss was measured. The decrease was 12 mg / dm ² . This test piece was epoxy resin (MP-7400 manufactured by Nitto Denko).
, And heated to 300 ° C. to perform a crack generation test. Six of the 20 tested cracked.

[0021]

As described above, the radiating plate for a semiconductor device made of aluminum or an aluminum alloy is subjected to anodizing treatment and then sealing treatment, whereby the adhesion with the sealing resin is improved, and the heat radiating plate is subjected to a heating test. A heat sink for a semiconductor device having excellent heat dissipation, electrical insulation, and low ionic contamination can be manufactured.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshio Hirayama 1-34-1 Kambara, Kambara-cho, Abara-gun, Shizuoka

Claims (2)

[Claims] 1. An aluminum or aluminum alloy radiator plate, wherein the anodic oxide coating applied to the radiator plate has a sealing degree value of 80 mg / dm ² or more. 2. A method for manufacturing a heat radiating plate made of aluminum or an aluminum alloy, wherein the anodic oxide film is sealed after the anodic oxidation treatment so as to have a sealing degree of 80 mg / dm ² or more, and then at 180 ° C. or more. A method for producing a heat sink made of aluminum or an aluminum alloy, which comprises performing a heat treatment.