JP6140526B2 - Aluminum alloy member - Google Patents

Description

  The present invention relates to an aluminum alloy member configured such that another member can be bonded to the surface by soldering.

  Aluminum alloy members tend to form a dense oxide film on the surface, and it is difficult to join other members to the surface by soldering. Therefore, a method of forming a metal film on the joint portion by plating is generally used for direct soldering joining to the aluminum alloy member. For example, Patent Document 1 discloses an example of a heat sink in which nickel-containing plating is applied to a joint surface between an aluminum fin and a copper plate.

JP 2002-324880 A

  However, when plating an aluminum alloy member, it is necessary to perform a ground treatment such as a zincate method, and it is difficult to shorten the plating process. Moreover, when performing plating, there exists a problem that processing cost becomes high.

  The present invention has been made in view of such a background, and intends to provide a high-quality and low-cost aluminum alloy member.

One aspect of the present invention is an aluminum alloy member having a base member made of an aluminum alloy and a soldering surface portion for soldering and joining another member to the base member,
The soldering surface portion includes a brazing material layer bonded to the surface of the base member,
A Ni foil layer brazed to the brazing material layer,
The brazing filler metal layer contains Si: 6 to 13% (mass%, the same applies hereinafter), Li: 0.004 to 0.1%, Be: 0.005 to 0.04%, Ba: 0.00. It contains one or more of 007 to 0.05%, Ca: 0.005 to 0.03%, Mg: 0.05 to 0.4%, and the balance is made of Al and inevitable impurities. An aluminum alloy member characterized by the above.

  In the aluminum alloy member, the Ni foil layer and the base member are joined by a brazing material layer. That is, the aluminum alloy member is configured to be formed by brazing a base member and a Ni foil layer prepared separately from the base member. Therefore, it is not necessary to perform plating when forming the soldering surface portion on the surface. As a result, the aluminum alloy member can be manufactured at a lower cost.

  The brazing filler metal layer has the specific chemical component composition. Thereby, brazing joining of a base member and Ni foil layer can be performed without using a flux in inert gas atmosphere. Therefore, when performing brazing joining of the Ni foil layer, problems such as bonding failure and unevenness due to gas generation from the flux are unlikely to occur. As a result, in the aluminum alloy member, the surface of the Ni foil layer becomes a smooth surface with almost no unevenness, and the surface of the Ni foil layer tends to be excellent in the quality of soldering joint. In addition, the aluminum alloy member is less likely to cause problems such as poor bonding and unevenness, and therefore tends to be excellent in conductivity and thermal conductivity.

  As described above, the aluminum alloy member has high quality and low cost.

Sectional drawing of the aluminum alloy member in an Example.

  In the above-mentioned aluminum alloy member, the aluminum alloy is a general term for metals mainly composed of aluminum including not only a narrowly defined aluminum alloy but also pure aluminum. Moreover, as a base member, various things can be used according to a use, such as a rolled sheet, an extrusion shape material, or a forged product, for example.

  In producing an aluminum alloy member, a Ni foil layer may be brazed and joined using a separately prepared base member and a brazing material layer. However, the base member and the brazing material layer have a base member as a core material. Alternatively, a two-layer clad material having a brazing material layer as a skin material may be constituted.

  That is, the Ni foil layer may be brazed and joined to a two-layer clad material having a base member as a core material and a brazing material layer as a skin material. In this case, the surface of the brazing material layer tends to be a flat surface with less unevenness. Therefore, the surface of the Ni foil layer tends to be smoother, and the quality of soldering joining on the surface of the Ni foil layer can be further improved.

  Further, the base member may be a heat radiating member that promotes cooling of the heat generating member joined to the soldering surface portion. As described above, the aluminum alloy member has a low thermal resistance and is likely to be excellent in thermal conductivity. Therefore, the aluminum alloy member can be suitably used as a heat radiating member that promotes cooling of the heat generating member. Examples of the heat radiating member include a heat radiator having a heat radiating fin portion such as a pin fin or a plate fin, and a heat exchanger having a refrigerant flow path therein. Further, examples of the heat generating member include semiconductor elements such as IGBT (Insulated Gate Bipolar Transistor) and LED (Light Emitting Diode), but other heat generating members can be used.

  Further, as described above, the aluminum alloy member may be configured such that the base member itself is a functional member having various functions such as a heat radiating member, but the aluminum alloy member is joined to a functional member separately prepared. It may be.

  In this case, in the aluminum alloy member, the base member is made of a plate material, and a second brazing material layer having the same chemical composition as the brazing material layer is bonded to the surface opposite to the surface on which the brazing material layer is provided. Can be configured. In this case, the aluminum alloy member and the functional member prepared separately can be brazed and joined by the second brazing material layer. Therefore, even if it is a functional member that exhibits a relatively complicated shape such as a shape with large irregularities or a shape with a curved surface, the soldering surface portion can be reliably and easily disposed by brazing the aluminum alloy member. Can do.

  Further, since the brazing filler metal layer and the second brazing filler metal layer have the same chemical composition, the brazing joining of the base member and the functional member is performed simultaneously with the brazing joining of the base member and the Ni foil layer. be able to. Therefore, the brazing joining process can be shortened.

  Further, the base member, the brazing material layer, and the second brazing material layer may constitute a three-layer clad material having the base member as a core material and the brazing material layer and the second brazing material layer as skin materials. That is, the Ni foil layer may be brazed and joined to a brazing material layer of a three-layer clad material having the base member as a core material and the brazing material layer and the second brazing material layer as skin materials. In this case, as in the case of using the above-described two-layer clad material, the quality of soldering joining to the Ni foil layer surface can be improved more easily.

  The second brazing material layer may be made of an aluminum alloy and joined with a heat radiating member that promotes cooling of the heat generating member joined to the soldering surface portion. As described above, the aluminum alloy member tends to have a low thermal resistance and a high thermal conductivity. Therefore, the heat radiating member joined with the aluminum alloy member is likely to be capable of efficiently cooling the heat generating member.

  Moreover, it is preferable that a brazing filler metal layer contains Si: 6-13%, Li: 0.004-0.1%, and has the chemical component composition which remainder consists of Al and an unavoidable impurity. In this case, it becomes easier to improve the quality of the brazing joint by the brazing material layer or the second brazing material layer.

  That is, since the brazing filler metal layer contains 6 to 13% Si, the amount of brazing supplied can be sufficiently increased. Thereby, also when performing brazing joining which does not use a flux in inert gas atmosphere, the quality of joining can be raised more.

  When the Si content is less than 6%, the wax tends to be insufficient, and the fluidity of the wax may be reduced. Therefore, in this case, the bonding quality may be deteriorated. On the other hand, when the Si content exceeds 13%, the amount of dissolution of the brazing material layer may be excessive, and coarse primary crystal Si is likely to be formed in the brazing material layer. Therefore, in this case, there is a possibility that a melting hole is generated in the base member during brazing joining.

  Li also has the effect of weakening the oxide film of the aluminum alloy and enhancing the fluidity of the wax. Thereby, also when performing brazing joining which does not use a flux in inert gas atmosphere, the quality of joining can be raised more.

If the Li content is less than 0.004%, the braze fluidity may be insufficient, and the oxide film may be insufficiently brittle. Therefore, in this case, the bonding quality may be deteriorated. On the other hand, when the content of Li exceeds 0.1%, Li ₂ O formed during brazing joining becomes excessive, so that the joining quality may be deteriorated.

  Further, the brazing filler metal layer further has Be: 0.005-0.04%, Ba: 0.007-0.05%, Ca: 0.005-0.03%, Mg: 0.05-0. You may contain 1 type, or 2 or more types out of 4%. Among these chemical components, Be, Ba, and Ca have an action of weakening the oxide film of the aluminum alloy. Moreover, Mg has the effect | action which improves the fluidity | liquidity of a wax in addition to the effect | action which weakens the oxide film of an aluminum alloy. Therefore, the brazing material layer made of an aluminum alloy containing these chemical components can further improve the quality of brazing joint. When the content of these chemical components is less than the lower limit of the specific range, the oxide film is not easily weakened, and it is difficult to obtain an effect of improving the quality of brazing joint. On the other hand, when the content of these chemical components exceeds the upper limit of the above specific range, the surface of the brazing material layer may be excessively oxidized, and in some cases, the quality of bonding may be deteriorated.

  The mechanism by which Be, Ba, Ca, and Mg weaken the oxide film of the aluminum alloy has not been completely elucidated, but the following mechanism is considered appropriate at present for Mg.

That is, Mg present in the molten wax is hardly oxidized due to the inert gas atmosphere, and is in a highly reactive state. Then, when Mg in the melt comes into contact with the oxide film (Al ₂ O ₃ ) present in the portion to be joined, it reacts with the oxide film to produce an AlMgO ₄ spinel compound. Thereby, it is thought that an oxide film can be made weak.

  The base member is preferably made of an aluminum alloy containing Mg: 0.2 to 1.3%. Since Mg in the base member is difficult to come into contact with the outside air, the presence ratio of MgO having low reactivity is reduced. Then, when heating for brazing joining is started, Mg begins to slowly diffuse toward the brazing filler metal layer, and rapidly diffuses into the molten liquid (brazing) as the brazing filler metal layer starts to melt. Therefore, in this case, it becomes easier to contain more highly reactive Mg in the brazing, and it becomes easier to improve the quality of brazing joining by the brazing filler metal layer or the second brazing filler metal layer.

  If the Mg content exceeds 1.3%, the melting point of the base member may be excessively lowered, and brazing joining may be difficult. On the other hand, when the Mg content is less than 0.2%, it is difficult to obtain the effect of improving the quality of bonding.

  In addition, the base member is further Mn: 0.05 to 1.8%, Si: 1.0% or less, Fe: 1.0% or less, Cu: 0.9% or less, Zn: 6.5% or less, One or two or more chemical components selected from the group consisting of Ti: 0.2% or less and Zr: 0.5% or less may be contained. As an aluminum alloy having such a chemical composition, for example, 3000 series (Al-Mn series), 5000 series (Al-Mg series), 6000 series (Al-Mg-Si series), or 7000 series (Al-Zn series). Alloys belonging to) can be used. These aluminum alloys can be appropriately selected according to the properties required for the aluminum alloy member such as strength, corrosion resistance, and formability.

  The Ni foil layer preferably has a thickness of 0.005 to 0.05 mm. Since the Ni foil layer and the base member have different thermal expansion coefficients, a difference occurs in the amount of shrinkage between the Ni foil layer and the base member in the process of cooling the aluminum alloy member after brazing joining. Therefore, when the thickness of the Ni foil layer exceeds 0.05 mm, the stress generated with the shrinkage becomes excessively large, and the resulting aluminum alloy member may be warped. Thereby, depending on the case, there exists a possibility that the solderability of the aluminum alloy member may deteriorate. On the other hand, the lower limit of the thickness of the Ni foil layer is not particularly limited, but it is difficult to produce a Ni foil layer having a thickness of less than 0.005 mm.

  Examples of the aluminum alloy member will be described below. As shown in FIG. 1, the aluminum alloy member 1 has a base member 2 made of an aluminum alloy and a soldering surface portion 3 for soldering and joining other members to the base member 2. The soldering surface portion 3 includes a brazing material layer 4 joined to the surface of the base member 2 and a Ni foil layer 5 brazed to the brazing material layer 4.

  The base member 2 is made of a plate material, and a second brazing material layer 7 having the same chemical composition as the brazing material layer 4 is joined to the surface opposite to the surface on which the brazing material layer 4 is provided. A base material 6 made of an aluminum alloy is brazed to the second brazing material layer 7.

  In this example, test materials (test materials 1 to 13) were prepared by using a plate material made of pure aluminum as the base material 6 and variously changing the chemical composition of the base member 2 and the brazing material layer 4 as shown in Table 1. The brazed jointability, smoothness and solder wettability of each test material were evaluated. Note that the thickness of the Ni foil layer 5 used in this example is 0.01 mm.

  The test material was produced according to the following procedure. First, a three-layer clad material having the base member 2 as a core material and the brazing material layer 4 and the second brazing material layer 7 as skin materials was produced and cut into a 70 mm square plate shape. The surface of the obtained three-layer clad material was degreased using a sodium carbonate-based degreasing agent.

  Next, the base material 6, the three-layer clad material and the Ni foil layer 5 are laminated so that the base material 6 and the second brazing material layer 7 are in contact with each other, and the Ni foil layer 5 and the brazing material layer 4 are in contact with each other. I let you. In this state, the base material 6, the three-layer clad material, and the Ni foil layer 5 were fixed so that the Ni foil layer 5 would not be displaced during brazing joining. In this example, a heat resistant spring was used to fix the base material 6, the three-layer clad material, and the Ni foil layer 5, and the entire surface of the Ni foil layer 5 was pressed with a surface pressure of 0.02 MPa.

  Then, the base material 6, the three-layer clad material, and the Ni foil layer 5 in a laminated state were heated at 600 ° C. for 3 minutes in a nitrogen atmosphere to perform brazing joining. In addition, about the test materials 1-12, although brazing joining was made | formed without using a flux, when the flux was not used about the test material 13, brazing joining was not made. Therefore, only the test material 13 was brazed and joined by applying a flux between the three-layer clad material and the Ni foil layer 5 and between the three-layer clad material and the substrate 6.

  For the test material 12, after brazing and joining, the obtained test material was immersed in room temperature nitric hydrofluoric acid (nitric acid 2% + hydrofluoric acid 1%) for about 60 seconds, washed with water, and the Ni foil layer 5. The surface was acid cleaned.

  About each test material (test materials 1-13) obtained by the above, brazing joining property, smoothness, and solder wettability were evaluated with the following method.

<Brazing bondability>
Using the ultrasonic flaw detector, the area of the joint portion by the brazing material layer 4 was measured, and the area ratio of the joint portion to the total area was calculated. The results are shown in Table 2. The larger the value of the area ratio of the bonded portion, the fewer defective bonding such as voids, which is a favorable result. Of the symbols shown in Table 2, A indicates that the area ratio of the joint portion is 95% or more, B indicates that the area ratio of the joint portion is 90% or more and less than 95%, and C indicates that the bonding is performed. The area ratio of the part is 70% or more and less than 90%, and D is a symbol indicating that the area ratio of the joint is less than 70%.

<Smoothness>
The height difference between the highest part and the lowest part on the surface of the Ni foil layer 5 was measured. The results are shown in Table 2. The difference in height of the Ni foil layer 5 indicates that the smaller the value, the smaller the unevenness and curvature of the surface of the Ni foil layer 5, and the smoother the surface of the Ni foil layer 5, which is a favorable result. Of the symbols shown in Table 2, A indicates that the height difference is 0.1 mm or less, B indicates that the height difference is between 0.1 mm and 0.3 mm, and C indicates that the height difference is 0. .3 mm and 0.5 mm or less, and D is a symbol indicating that the height difference exceeds 0.5 mm.

<Solder wettability>
With the lead-free solder having a melting point of about 210 ° C. placed on the Ni foil layer 5, the test material was heated using a hot plate, and the temperature of the test material was maintained at 240 ° C. for 1 minute. Thereafter, the test material was removed from the hot plate and cooled to room temperature to solidify the lead-free solder. The contact angle of lead-free solder in this state was measured. The results are shown in Table 2. The smaller the value of the contact angle, the higher the solder wettability, which is a favorable result. Of the symbols shown in Table 2, A indicates that the contact angle is 30 ° or less, B indicates that the contact angle is greater than 30 ° and not greater than 60 °, and C indicates that the contact angle is greater than 60 ° and 90 °. The symbol D indicates that the contact angle exceeds 90 °, and D indicates that the contact angle exceeds 90 °.

  As is known from Tables 1 and 2, the test materials 1 to 12 include a brazing material layer 4 having the above specific chemical component composition. Therefore, good results were obtained with respect to any of the properties of brazing joint property, smoothness and solder wettability.

  Moreover, the test materials 10-12 are equipped with the base member 2 which has the said specific chemical component composition in addition to the brazing filler metal layer 4 which has the chemical component composition of the said characteristic. Therefore, the brazing bondability was better.

  Moreover, the test material 12 performs the acid cleaning of the Ni foil layer 5 in addition to the brazing material layer 4 and the base member 2 having the specific chemical component composition. Therefore, the oxide, dirt, etc. present on the surface of the Ni foil layer 5 have been removed after the brazing joint, and the solder wettability was better.

  On the other hand, since the test material 13 could not be brazed without using the flux as described above, it was brazed using the flux. For this reason, voids and the like are generated along with the gas generated from the flux, there are many unjoined portions, and the smoothness is poor.

DESCRIPTION OF SYMBOLS 1 Aluminum alloy member 2 Base member 3 Soldering surface part 4 Brazing material layer 5 Ni foil layer 6 Base material 7 2nd brazing material layer

Claims (10)

An aluminum alloy member having a base member made of an aluminum alloy and a soldering surface portion for soldering and joining another member to the base member,
The soldering surface portion includes a brazing material layer bonded to the surface of the base member,
A Ni foil layer brazed to the brazing material layer,
The brazing filler metal layer contains Si: 6 to 13% (mass%, the same applies hereinafter), Li: 0.004 to 0.1%, Be: 0.005 to 0.04%, Ba: 0.00. It contains one or more of 007 to 0.05%, Ca: 0.005 to 0.03%, Mg: 0.05 to 0.4%, and the balance is made of Al and inevitable impurities. An aluminum alloy member characterized by the above.   2. The aluminum alloy member according to claim 1, wherein the Ni foil layer is brazed and joined to a two-layer clad material having the base member as a core material and the brazing material layer as a skin material.   The aluminum alloy member according to claim 1, wherein the base member is a heat radiating member that promotes cooling of the heat generating member joined to the soldering surface portion.   The base member is made of a plate material, and a second brazing material layer having the same chemical composition as the brazing material layer is joined to a surface opposite to the surface on which the brazing material layer is provided. The aluminum alloy member according to claim 1.   The Ni foil layer is brazed and joined to the brazing material layer of a three-layer clad material having the base member as a core material and the brazing material layer and the second brazing material layer as skin materials. The aluminum alloy member according to claim 4.   The heat radiation member which accelerates | stimulates cooling of the heat generating member which consists of aluminum alloys and is joined to the said soldering surface part is brazed and joined to the said 2nd brazing material layer. Aluminum alloy member.   The brazing filler metal layer contains Si: 6 to 13%, Li: 0.004 to 0.1%, and the balance has a chemical composition composed of Al and inevitable impurities. The aluminum alloy member according to any one of 6.   The brazing filler metal layer further includes Be: 0.005 to 0.04%, Ba: 0.007 to 0.05%, Ca: 0.005 to 0.03%, Mg: 0.05 to 0.4. The aluminum alloy member according to claim 7, wherein the aluminum alloy member contains 1 type or 2 types or more of%.   The aluminum alloy member according to any one of claims 1 to 8, wherein the base member is made of an aluminum alloy containing Mg: 0.2 to 1.3%.   The aluminum alloy member according to any one of claims 1 to 9, wherein the Ni foil layer has a thickness of 0.005 to 0.05 mm.

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