JP2002361408A - Method for joining joined product of different kinds of metals - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently braze a copper-made heat conductive plate and an aluminum-made cooling fin having large difference in plate thickness between both metals. SOLUTION: Under the state of arranging a nickel layer 113 on the joining surface 112 with the fin 130 on the plate 110 and also, disposing a joining plate 114 composed of an aluminum-made core material 114b cladding brazing materials 114a on both front and back surfaces between the heat conductive plate 110 and the cooling fin 130, the heating and brazing are performed. In this way, when the brazing is performed, since the aluminum-made core material 114b is joined with the plate 130 while melting as a sacrificial material instead of the fin 130 by reacting the brazing material and the nickel, it can be prevented to melt down the fin 130 from happening when the brazing is performed. Therefore, even in the case the thickness of the fin 130 is very thinner in comparison with the thickness of the plate 110, the fin 130 and the plate 110 can sufficiently be brazed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining dissimilar metal joints in which a first member made of copper and a second member made of aluminum are joined.
The present invention is effective when applied to a heating element cooling device for cooling electronic components that generate heat, such as a PU) and an inverter.

[0002]

2. Description of the Related Art Conventionally, a cooler (heat sink) for cooling electronic components has been made of aluminum. The general structure of the heat sink is composed of a heat transfer plate portion that comes into contact with the core of the electronic component (the portion where the semiconductor is integrated), and cooling fins provided on the heat transfer plate portion. The heat plate and the cooling fins are integrated by means of extrusion or drawing, brazing (soldering), or the like.

[0003] In recent years, as the operating speed of electronic components has increased and the amount of heat generated from the electronic components has increased, it has become difficult to sufficiently cool the electronic components with a conventional aluminum heat sink. .

On the other hand, a method of forming a heat sink using copper having a higher thermal conductivity than aluminum is considered. However, since copper has a higher density than aluminum, if the heat sink is entirely made of copper, the heat sink becomes very heavy. It is difficult to attach the heat sink to the (motherboard).

[0005] The inventors of the present invention have made a trial of a heat sink in which the heat transfer plate in contact with the electronic component is made of copper, the cooling fin is made of aluminum, and the heat transfer plate and the cooling fin are brazed and joined. In this prototype, the following problems occurred.

That is, in order to increase the cooling capacity of the heat sink, it is necessary to increase the heat radiation area. However, if the heat radiation area is simply increased, the entire heat sink becomes large. By
It is necessary to suppress an increase in the outer dimensions of the cooling fin (the outer diameter of the heat sink) while increasing the surface area of the cooling fin.

On the other hand, since the heat transfer plate needs to conduct the heat generated by the electronic component in contact with the electronic component to the cooling fins, the thickness of the heat transfer plate (the cross-sectional area of the portion where the heat is transmitted) is sufficient. It is necessary that the heat transfer plate and the cooling fin have a large difference (less than 1/70 in the above prototype). I will.

[0008] When brazing aluminum and copper, a method of brazing with an aluminum (AL) -silicon (Si) brazing material in a state where the copper side is plated with nickel is generally used. But when brazing,
Since the brazing material (AL-Si) and nickel react with each other to lower the melting point of aluminum, there has been a problem that, during brazing, cooling fins having a small thickness and a small heat capacity are melted.

In view of the above, it is an object of the present invention to satisfactorily braze a copper member and an aluminum member having greatly different plate thicknesses.

[0010]

According to the present invention, in order to achieve the above object, the first aspect of the present invention comprises a first copper material.
Member (110) and second member made of aluminum (130)
And a method for joining dissimilar metal joints in which a nickel layer (113) is provided on the joint surface (112) of the first member (110) with the second member (130). It is characterized in that the brazing is performed by heating in a state where an aluminum joining member (114) coated with a brazing material on both front and back surfaces is provided between the member (110) and the second member (130).

Thus, at the time of brazing, the brazing material and nickel react with each other to form an aluminum joining member (114).
However, since it is joined to the first member (110) while melting as a sacrificial material instead of the second member (130), it is possible to prevent the second member (130) from melting during brazing. .

On the other hand, since the second member (130) is not affected by the nickel, the second member (130) does not melt itself and the joining member (1) does not melt.
Since it is brazed to 14), the second member (130)
It is joined to the first member (110) via the joining member (114).

As described above, according to the present invention, even if the thickness of the second member (130) is very thin compared to the thickness tp of the first member (110), the second member (130) and the first member (110) can be satisfactorily brazed.

According to a second aspect of the present invention, there is provided a dissimilar metal joined product in which a first member made of copper (110) and a second member made of aluminum (130) are joined, and the first member (11)
0), a nickel layer (113) is provided on the joint surface (112) side with the second member (130), and a brazing material is provided between the first member (110) and the second member (130) on both front and back surfaces. It is characterized in that it is heated and brazed with the coated aluminum joining member (114) provided.

Thus, at the time of brazing, the brazing material and nickel react with each other to form an aluminum joining member (114).
However, since it is joined to the first member (110) while melting as a sacrificial material instead of the second member (130), it is possible to prevent the second member (130) from melting during brazing. .

On the other hand, since the second member (130) is not affected by the nickel, the second member (130) does not melt itself and the joining member (1) is not melted.
Since it is brazed to 14), the second member (130)
It is joined to the first member (110) via the joining member (114).

As described above, according to the present invention, even if the thickness of the second member (130) is very thin compared to the thickness tp of the first member (110), the second member (130) and the first member (110) can be satisfactorily brazed.

Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment)
Using a microprocessor (MPU) as a heating element, this M
FIG. 1 is a perspective view of a cooling device 100 in which the present invention is applied to a heating element cooling device (hereinafter, referred to as a heat sink) that cools a PU.

In FIG. 1, reference numeral 110 denotes a heat transfer plate (first member) made of copper (C1100 in this embodiment) formed in a substantially square shape, and an MPU (not shown) includes a cooling fin described later. On the opposite side to the heat transfer plate 110 (hereinafter, abbreviated as the plate 110) at the approximate center thereof.

Reference numeral 120 denotes an axial-flow box fan (blower means) for blowing cooling air toward the plate 110 from a direction substantially perpendicular to the plate surface 111 of the plate 110. 120
Abbreviated. ), An axial fan 122 and an axial fan 12 in a rectangular parallelepiped box 121 as shown in FIG.
2 that accommodates a small electric motor 123 that drives the motor 2.

Then, the fan 120 and the plate 110
A cooling fin (second member) 130 made of aluminum (in the present embodiment, A7172) for facilitating heat radiation from the plate 110 by rolling a thin aluminum plate into a roller shape is disposed between the cooling fin 130 and the (plate surface 111). The cooling fins 130 (hereinafter, abbreviated as fins 130) are provided with a plurality of well-known louvers 131 for turning the air flow in a predetermined direction as shown in FIG. Is attached.

Reference numeral 140 denotes the fin 130 and the fan 12
0, and is a support casing made of aluminum that supports the fan 120 and forms a passage for air blown out of the fan 120. As shown in FIG. The passage is formed in a tapered shape (a divergent shape) such that the passage cross-sectional area increases toward the fin 130 side.

As shown in FIG. 1, a portion of the support casing 140 which comes into contact with the ridges (tips) of the fins 130 is substantially parallel to the plate 110 and
Two flat portions 141 are formed extending in a direction substantially perpendicular to the longitudinal direction of the 30 ridges (regions connecting the tops of the peaks) (hereinafter, this direction is referred to as a corrugated fin advancing direction). On both ends in the longitudinal direction of these two flat portions 141, support portions 142 extending from the flat portion 141 to the plate 110 and fixing the support casing 140 to the plate 110 are formed. The flat portion 141
Are joined to the fins 130 at both ends in the ridge direction of the fin portion of the fin 130, and the flat portion 141 is also formed between the two flat portions 141 in the tapered (divergent) portion of the support casing 140. Have been.

The fan 120 is provided with a screw (small screw) 1 penetrating through the box 121 and reaching the support casing 140.
24 fixed to the support casing 140. As shown in FIG. 3, a female screw portion 143 into which the screw 124 is screwed and an opening 144 for introducing blast air are formed in a portion of the support casing 140 corresponding to the fan 120.

Next, a method of brazing the plate 110 and the fins 130 and their features will be described with reference to FIG.

First, a nickel layer 113 is provided by applying nickel plating to at least the joint surface 112 of the plate 110 with the fins 130 (in the present embodiment, the entire surface of the plate 110). A bonding plate (bonding member) 114 made of an aluminum core material 114b covered (cladded) with a brazing material (AL-Si-based A4045 in this embodiment) 114a is disposed between the front and back surfaces. And brazing by heating in a furnace.

Thus, at the time of brazing, the brazing material (AL
-Si) and nickel react with each other and the aluminum core 114b (joining plate 114) is melted and joined to the plate 110 instead of the fin 130 as a sacrificial material. It can be prevented from melting.

On the other hand, since the fins 130 are not affected by nickel, the fins 130 are not melted by themselves, and
The fins 130 are joined to the plate 110 via the joining plate 114.

As described above, according to the present embodiment, even if the thickness tf of the fin 130 is extremely thin (less than 1/70 in this embodiment) compared to the thickness tp of the plate 110,
Since the fins 130 and the plate 110 can be satisfactorily brazed, the cooling capacity of the heat sink 100 can be improved while preventing the heat sink 100 from becoming extremely heavy.

By the way, the thickness of the core material 114b only needs to be 0.5 mm or more and 2 mm or less, since it is sufficient that the core material 114b functions as a sacrificial material at the time of brazing. In the embodiment, it is 0.6 mm. The thickness of the nickel layer 113 is
Since it is sufficient if the thickness is sufficient for brazing to 14, the thickness is usually 5 μm or more and 29 μm or less, and is 17 μm in the present embodiment.

(Second Embodiment) In this embodiment, as shown in FIG. 5, the fins 130 are provided in a plurality of stages (in FIG. 5, two stages). 1
A joining plate 115 coated with a brazing material on both the front and back surfaces is disposed between the two fins 30, and the two fins 130 are brazed via the joining plate 115.

The joining plate 115 is a plate 1
Joining plate 1 disposed between the fin 10 and the fin 130
Unlike 14, it does not function as a sacrificial material,
While preventing the fins 130 of the second (upper) stage from being fitted into the fins 130 of the first (lower) stage,
It functions as a brazing material for brazing.

Next, the features of this embodiment will be described.

In this embodiment, the brazing of aluminum and aluminum (brazing of fins) and the brazing of aluminum and copper (plate 110 and fins 13) are performed.
And brazing with different brazing temperatures are mixed together. Normally, when brazing with different brazing temperatures is mixed, temperature control during brazing is performed. There is a problem that the brazing work is difficult because it needs to be managed finely (strictly).

However, in the present embodiment, the brazing of aluminum and copper (the brazing of the plate 110 and the fins 130) is performed with the joining plate 114 interposed therebetween, as in the first embodiment. Since the brazing is performed, as described above, even if the temperature is not strictly controlled for the brazing of aluminum and copper (the brazing of the plate 110 and the fins 130), the problem that the fins 130 melt does not occur.

Therefore, even when brazings having different brazing temperatures are mixed, it is not necessary to precisely (strictly) control the temperature at the time of brazing, so that the brazing operation can be easily performed.

(Other Embodiments) In the above embodiment, the present invention is applied to a heat sink. However, the present invention is not limited to this, and can be applied to other dissimilar metal joined products.

In the above-described embodiment, the nickel layer 113 is formed by plating. However, the present invention is not limited to this. By cladding (preferably, vacuum rolling) the copper plate 110, the present invention is not limited thereto. A nickel layer may be formed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a heat sink according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of FIG. 1 cut in the axial direction of the electric motor.

FIG. 3 is a perspective view showing a state in which a fan is removed from the heating element cooling device according to the embodiment of the present invention.

FIG. 4A is an explanatory view of a brazing method according to the first embodiment of the present invention, and FIG. 4B is an enlarged view of a portion A of FIG.

FIG. 5 is an explanatory diagram of a brazing method according to a second embodiment of the present invention.

[Explanation of symbols]

110: heat transfer plate (first member), 130: cooling fin (second member), 113: nickel layer, 114: joining plate (joining member), 114a: brazing material, 114b: core material.

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Claims (2)

[Claims] 1. A method for joining dissimilar metal joints in which a first member made of copper (110) and a second member (130) made of aluminum are joined, wherein the first member (110) includes Two members (130)
A nickel layer (113) is provided on the side of the bonding surface (112) between the first member (110) and the first member (110) and the second member (130). A method for joining dissimilar metal joints, comprising heating and brazing with the member (114) disposed. 2. A dissimilar metal joined product in which a first member (110) made of copper and a second member (130) made of aluminum are joined, wherein the second member (110) of the first member (110) is provided. 130)
A nickel layer (113) is provided on the side of the joint surface (112) with the first member (110) and the second member (130).
A dissimilar metal joined product characterized by being heated and brazed in a state where an aluminum joining member (114) covered with a brazing material on both front and back surfaces is disposed between the two.