JP4014433B2 - Method for producing aluminum alloy-silicon carbide composite and structure used therefor - Google Patents

Description

【００３６】
表１の実施例１と比較例１との対比から、本発明によれば、従来の一個取り法と同等寸法かつ同等曲げ強度を有するアルミニウム合金−炭化珪素質複合体の二個を製造できたことがわかる。また、四個取りを行っても、設計寸法かつ高曲げ強度を有するアルミニウム合金−炭化珪素質複合体を製造することができた（実施例２）。
【００３７】
【発明の効果】
本発明の構造体によれば、アルミニウム合金−炭化珪素質多孔体を１個の枠を用いて多数個のアルミニウム合金−炭化珪素質多孔体を製造することができる。また、本発明のアルミニウム合金−炭化珪素質多孔体の製造方法によれば、アルミニウム合金−炭化珪素質多孔体を容易に製造することができる。
【図面の簡単な説明】
【図１】アルミニウム合金−炭化珪素質複合体を製造するための構造体の概略正面図
【図２】ユニットの概略横断面図
【図３】別のユニットの概略横断面図
【符号の説明】
１ 枠
２ 炭化珪素質多孔体
３ ユニット
４ スペーサー
５ａ 左端板
５ｂ 右端板
６ 仕切[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aluminum alloy-ceramic composite suitable as a heat sink for a hybrid integrated circuit board, and a structure used therefor.
[Prior art]
[0002]
A metal circuit made of copper or aluminum is formed on the surface of a ceramic substrate such as an aluminum nitride substrate or a silicon nitride substrate having high insulation and high thermal conductivity, and a metal heat sink made of copper or aluminum is formed on the back surface. This circuit board is used as a power module board. Today, as the integration and size of semiconductor elements increase, the amount of heat generated continues to increase, and how to efficiently dissipate heat is an issue.
[0003]
A typical heat dissipation structure for a conventional circuit board is formed by soldering a heat sink to the back surface (metal heat dissipation plate) of a circuit board via a base metal plate (for example, a copper plate). It was general. However, in this structure, when a thermal load is applied to the semiconductor device, a crack caused by the difference in thermal expansion coefficient between the heat sink and the circuit board occurs in the solder, resulting in insufficient heat dissipation and causing the semiconductor to malfunction. There were cases where problems such as damage occurred.
[0004]
Therefore, an aluminum alloy-silicon carbide composite has been proposed and attracted attention as a heat sink having a thermal expansion coefficient close to that of a circuit board.
[0005]
What is important when producing an aluminum alloy-silicon carbide based composite is to improve the wettability of silicon carbide and aluminum alloy to make them denser. Conventionally, silicon carbide particles or fibers and aluminum metal powder After mixing, powder metallurgy method to compound at high temperature and high pressure, die casting method to create a porous body (preform) with silicon carbide particles or fibers and compound molten aluminum alloy at high temperature and high pressure, high pressure forging The law is adopted.
[0006]
In powder metallurgy, since densification is insufficient and thermal characteristics are not so good, and expensive processing such as diamond is necessary, many are performed by die casting or high pressure forging. In the die-cast method, there is a problem that equipment costs are increased because molds are arranged according to shapes and equipment suitable for them is required. The high-pressure forging method does not have this problem, but it is necessary to impregnate the preform with molten aluminum alloy using a large pressure vessel, so the aluminum alloy lump that will eventually be removed is around the preform. There are problems that a lot of machining is required to remove and remove a large amount of machining waste, and that the amount of processing waste is increased.
[0007]
Therefore, in the high pressure forging method, one preform is housed in an iron frame having at least one open surface so that the minimum necessary molten aluminum alloy is in contact with the preform. However, in this method, one steel frame is required for one preform, so the productivity is very low.
[0008]
[Problems to be solved by the invention]
In view of the above, an object of the present invention is to provide a method for improving the productivity of an aluminum alloy-silicon carbide composite and a structure used therefor. The object of the present invention can be achieved by using a plurality of porous silicon carbide porous bodies that are partitioned and housed in a frame having partitions.
[0009]
[Means for Solving the Problems]
That is, the present invention comprises a block in which a plurality of units 3 are arranged or stacked via spacers 4, and the unit includes a plurality of silicon carbide porous bodies 2 partitioned within a frame 1. 6 is a structure for producing an aluminum alloy-silicon carbide composite, characterized in that it is partitioned and accommodated at 6. Further, in the present invention, after placing the structure in a pressurized container, the molten aluminum alloy is filled, pressurized, impregnated into a silicon carbide porous body and cooled, and then an aluminum alloy-silicon carbide A method for producing an aluminum alloy-silicon carbide composite comprising separating the composite.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings.
[0011]
FIG. 1 is a schematic front view showing an example of a structure (hereinafter also simply referred to as “structure”) for producing the aluminum alloy-silicon carbide composite of the present invention. 2 and 3 are schematic cross-sectional views showing examples of embodiments of the unit. Reference numeral 1 is a frame, 2 is a silicon carbide based porous material, 3 is a unit, 4 is a spacer, 5a is a left end plate, 5b is a right end plate, and 6 is a partition provided on the frame 1.
[0012]
The frame 1 used in the present invention has a partition 6. There are no particular limitations on the shape and number of the partitions, and any structure can be used as long as a plurality of silicon carbide based porous bodies can be anchored without being easily detached. 2 and 3 show examples in which two or four silicon carbide porous bodies are housed by the protruding ribs, but the protruding ribs (partition wall structure) may be used without being limited to the protruding ribs. Further, the number can be appropriately changed depending on the number of silicon carbide based porous materials to be accommodated. In order to recycle the processing waste, it is preferable that the processing waste has as little impurities as possible. Therefore, it is desirable to make the partition as small as possible, and it is preferable to use a protruding rib.
[0013]
In the present invention, the frame 1 becomes the structure of the present invention (for example, FIG. 1) through the unit 3, and when this is pressed soaked in a molten aluminum alloy bath in a pressurized container, the molten aluminum alloy is silicon carbide. Since the porous porous body must be impregnated, measures such as opening the upper and lower surfaces of the frame 1 and providing a separate inlet for the molten aluminum alloy so that the molten aluminum alloy enters the frame, etc. Must be given.
[0014]
As the material of the frame, iron, an aluminum alloy, ceramics, or the like is used, but an aluminum alloy is preferable in consideration of not containing impurities as much as possible in the processing waste.
[0015]
Moreover, it is preferable that the mold release agent is apply | coated to the part of the frame which contacts a silicon carbide based porous body. Thereby, the aluminum alloy-silicon carbide composite can be easily separated. As the release agent, a carbon-based or alumina-based one is used. Specifically, it is HITAZOL GA-242B (manufactured by Hitachi Powder Metallurgy).
[0016]
The silicon carbide based porous material 2 used in the present invention preferably has uniform pores and a relative density of 60 to 70% by volume. There is no restriction | limiting in the shape of a silicon carbide based porous body. When it is desired to provide holes, grooves, etc. in the aluminum alloy-silicon carbide based composite, if the corresponding holes, grooves, etc. are formed in the silicon carbide porous body, the final product is processed by filling the aluminum alloy. Therefore, formation of holes, grooves, etc. is facilitated.
[0017]
The silicon carbide based porous material is a method in which a mixed raw material powder containing a silicon carbide powder and an inorganic binder such as silica sol is molded and then fired in an inert atmosphere such as air or nitrogen. And a method of kneading, molding, drying and firing, an injection method of firing after adding a binder to silicon carbide powder, and the like. The porosity can be adjusted by the particle size of the silicon carbide powder, the pressure during molding, and the like.
[0018]
If an example of a mixing | blending of raw material powder is shown, it will be 11-13 parts of inorganic binders with respect to 100 parts (mass part, the same hereafter) of silicon carbide powder. Baking is performed in the air at a temperature of 800 to 900 ° C. for 0.5 to 2 hours. Production of a silicon carbide based porous material having a relative density of 60 to 70% by volume is facilitated by using two kinds of silicon carbide powders having an average particle diameter of 70 to 110 μm and an average particle diameter of 7 to 12 μm.
[0019]
The structure of the present invention is a block in which a plurality of units 3 are arranged or stacked via spacers 4. The number of units is preferably as large as possible. If the dimensions are 100 to 300 mm in length, 100 to 300 mm in width, and 3 to 10 mm in thickness, up to about 50 units are possible depending on the dimension in the width direction of the pressurized container. Blocking is preferably performed by means such as using an end plate and fastening the whole with screws or bundling with wires. By using the end plate, contact with the molten aluminum alloy can be avoided, so that the final shape can be easily processed. FIG. 1 shows an example in which the left end plate 5a and the right end plate 5b are screwed.
[0020]
When arranging or stacking units, when the structure of the present invention is immersed in a molten aluminum alloy bath and pressure is applied, it is considered that the molten aluminum alloy is distributed to all silicon carbide based porous bodies in the unit. Done. From this point of view, it is not recommended to place the spacer in close contact with the entire surface of the silicon carbide based porous material, and it is desirable to provide an appropriate open surface and use it as an entrance for the molten aluminum alloy. In addition, it is preferable that the mold release agent is apply | coated to the surface which a spacer and a silicon carbide porous body contact | connect for the same reason as the above.
[0021]
As the material for the end plate and spacer, iron, aluminum alloy, ceramics, and the like are used, but aluminum alloy is preferable in consideration of not containing impurities as much as possible in the processing waste.
[0022]
Next, a method for producing the aluminum alloy-silicon carbide composite of the present invention will be described.
[0023]
First, the structure of the present invention is placed in a pressure vessel such as a product. The number of arrangement may be singular or plural. The arrangement is preferably, but not limited to, the end plate surface of the structure placed parallel or perpendicular to the bottom surface of the pressurized container. FIG. 1 shows an example of vertical arrangement. Thereafter, the molten aluminum alloy is filled and pressurized to impregnate the silicon carbide porous body. The pressurization is preferably performed by applying a pressure of 30 to 45 GPa for 10 to 30 minutes. Impregnation becomes easier as the pressure is higher, but if it exceeds 45 GPa, it is necessary to increase the pressure resistance of the equipment used, and the equipment cost increases.
[0024]
As the molten aluminum alloy, an aluminum-silicon alloy containing 5 to 18% by mass of silicon is preferable from the viewpoint of thermal expansion of the final product. Further, from the viewpoint of further improving the wettability with the silicon carbide based porous material, an aluminum-silicon-magnesium alloy to which 0.1 to 2.0% by mass of magnesium is added is preferable. The melting temperature is preferably 700 to 900 ° C.
[0025]
After impregnation, the aluminum alloy lump enclosing the aluminum alloy-silicon carbide composite is cooled until it can be machined. Although natural cooling is sufficient for cooling, forced cooling may be performed.
[0026]
Next, after cutting to approximately unit units using a commercially available cutting machine (for example, “Band saw” manufactured by Daito Seiki Co., Ltd.), the frame is removed by punching. At this stage, since a plurality of aluminum alloy-silicon carbide composites are connected by the aluminum alloy, cutting into a unit body of the aluminum alloy-silicon carbide composite by laser processing, end milling, etc. It becomes an aluminum alloy-silicon carbide composite.
[0027]
In the case of laser processing, after dividing grooves (for example, 10 mm cuts at intervals of 5 mm) are applied by a laser, an impact or the like is applied to divide the aluminum alloy-silicon carbide composite unit body. If necessary, it is ground with a grinder. In the case of end mill processing, when this processing is finished, the final product is an aluminum alloy-silicon carbide composite.
[0028]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
[0029]
Example 1
Commercially available silicon carbide powder A (average particle size 100 μm), silicon carbide powder B (average particle size 13 μm) and silica sol (trade name “Snowtex” manufactured by Nissan Chemical Co., Ltd.) are blended at a mass ratio of 58:31:11. After 50 minutes of stirring and mixing, the molded body was pressure-molded at 6 MPa. This was heated in the atmosphere at a temperature of 850 ° C. for 1 hour to produce a silicon carbide based porous material 2 (porosity 35 volume%, bending strength 5 MPa).
[0030]
The frame 1 shown in FIG. 2 (inner size is 145 mm long × 77 mm wide × 2.95 mm thick. There is a partition of protruding ribs of 15 mm long × 3 mm wide at a position 37 mm from the lateral end face). The unit 3 was configured by accommodating the silicon carbide based porous material 2 (length 36.4 mm × width 144.1 mm × thickness 2.9 mm). Thirty pieces of them are spacer 4 (length 169 mm × width 100 mm × thickness 0.8 mm iron plate), left end plate 5 a (length 198 mm × width 126 mm × thickness 12 mm iron plate), right end plate 5 b (length 198 mm × width 126 mm × thickness). 12 mm iron plate), and the whole was blocked with bolts and nuts to form a structure (see FIGS. 1 and 2). When arranging the units, an intrusion port for molten aluminum alloy was provided to allow them to communicate with each other. This intrusion port was formed by closely attaching 1/2 of the surface area of the silicon carbide based porous material with a spacer and opening the remaining 1/2.
[0031]
Example 2
The frame 1 shown in FIG. 3 (inner length is 145 mm × width 77 mm × thickness 2.95 mm. A partition of protruding ribs of length 15 mm × width 3 mm at a position 33.5 mm from the horizontal end surface, 67.5 mm from the vertical end surface Except that the projecting rib partition of 10 mm in length x 15 mm in width is used, and four silicon carbide porous bodies 2 (length 32.9 mm x width 66.8 mm x thickness 2.9 mm) are stored. A structure was manufactured according to Example 1 (see FIGS. 1 and 3).
[0032]
Comparative Example 1
A structure was produced in the same manner as in Example 1 except that one silicon carbide based porous material was housed in a non-partitioned frame (inside length 145 mm × width 37 mm × thickness 2.95 mm).
[0033]
Two of the above structures were heated in an electric furnace to a temperature of 600 ° C. and then arranged almost uniformly in an iron pressure vessel (300 mm × 240 mm × 390 mm) heated to 200 ° C. The arrangement was performed with the end plate surface of the structure perpendicular to the bottom surface of the pressurized container (state shown in FIG. 1). Thereafter, a molten aluminum alloy (temperature: 820 ° C.) of silicon 12 mass% -magnesium 0.5 mass% -aluminum alloy was poured, and after applying a pressure of 60 MPa for 15 minutes, it was taken out from the pressure vessel and naturally cooled to room temperature. .
[0034]
Next, the frame was removed by punching after cutting almost to unit units with a cutting machine (trade name “Bandsaw” manufactured by Daito Seiki Co., Ltd.). At this stage, since a plurality of aluminum alloy-silicon carbide based porous bodies are connected by the aluminum alloy, they were divided by hand after dividing grooves by laser processing. The external dimensions of the obtained aluminum alloy-silicon carbide composite were measured with calipers. Moreover, the test body (3 mm x 3 mm x 40 mm) was processed using the diamond processing jig | tool, and room temperature 3-point bending hardness was measured. The results are shown in Table 1.
[0035]
[Table 1]

[0036]
From the comparison between Example 1 and Comparative Example 1 in Table 1, according to the present invention, two aluminum alloy-silicon carbide composites having the same dimensions and the same bending strength as those of the conventional single-chip method could be manufactured. I understand that. Further, even when four pieces were taken, an aluminum alloy-silicon carbide composite having design dimensions and high bending strength could be produced (Example 2).
[0037]
【The invention's effect】
According to the structure of the present invention, a large number of aluminum alloy-silicon carbide based porous bodies can be produced using a single frame. Moreover, according to the manufacturing method of the aluminum alloy-silicon carbide based porous material of the present invention, the aluminum alloy-silicon carbide based porous material can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic front view of a structure for producing an aluminum alloy-silicon carbide composite. FIG. 2 is a schematic cross-sectional view of a unit. FIG. 3 is a schematic cross-sectional view of another unit.
1 Frame 2 Silicon carbide based porous body 3 Unit 4 Spacer 5a Left end plate 5b Right end plate 6 Partition

Claims (1)

  A plurality of units (3) are composed of blocks arranged or stacked via spacers (4), and the unit has a plurality of silicon carbide porous bodies (2) in a frame (1). The molten aluminum alloy inlet is formed by being partitioned and accommodated by the partition (6), and by adhering 1/2 of the surface area of the porous silicon carbide body with the spacer (4) and opening the remaining 1/2. After placing the structure formed in a pressurized container, filling the molten aluminum alloy, pressurizing and impregnating and cooling the silicon carbide porous body, the aluminum alloy-silicon carbide composite A method for producing an aluminum alloy-silicon carbide composite comprising separating.

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