KR20140112505A - Method for surface brazing between aluminum alloy member and copper alloy member - Google Patents

Abstract

A method of brazing and brazing an aluminum alloy member and a copper alloy member in a fluxless manner using a single-layered brazing sheet is characterized in that 1.0 to 12 mass% of Si, 0.1 to 5.0 mass% of Mg, Layer brazing sheet having a component composition containing Al and inevitable impurities and having a thickness of 15 to 200 mu m is interposed and brought into contact with the surface of the single-layer brazing sheet so that the brazing temperature 510 The aluminum alloy member and the copper alloy member are brazed in a flux-free manner while applying a surface pressure of 0.6 MPa or more.

Description

[0001] METHOD FOR SURFACE BRAZING BETWEEN ALUMINUM ALLOY MEMBER AND COPPER ALLOY MEMBER [0002]

The present invention relates to a method for brazing an aluminum alloy member and a copper alloy member in a flux-less atmosphere in an inert gas atmosphere using a brazing sheet.

2. Description of the Related Art In recent years, there has been an increasing demand for a heat exchange system for cooling the heat generated by an in-vehicle IGBT by surface contact, and a technique for surface brazing of an aluminum member and a copper member is required. For example, in the case of joining a substrate having a good thermal conductivity and electrical insulation property to a water-cooled member made of an aluminum alloy, the aluminum plate surface of the copper plate and the aluminum alloy surface of the water-cooled member are brazed Technology is needed.

In this surface brazing technique, a solder material is interposed between an aluminum alloy member and a copper plate to thermally braze it, so that voids are likely to be generated in the joint, and when the flux is used, the flux is easily sealed have. Therefore, it is a relatively difficult technique in brazing technology.

On the other hand, as a technique of surface brazing bonding of an aluminum member and a copper member which do not use flux, there is a surface brazing bonding technique using a vacuum brazing method. For example, in Non-Patent Document 1, an Al-Si-Mg-Bi based thin brazing material (equivalent to 4104, melting point: 832K) is sandwiched between an aluminum plate A1050 and an oxygen free copper plate C1020 and an initial load of 0.1 MPa In addition, there is proposed a technique of surface brazing by maintaining the temperature at 783 to 823 K (510 to 550 ° C) in a vacuum furnace. In the technique disclosed in the non-patent document 1, diffusion of Al into the Cu base material becomes active during the brazed holding time to generate the intermetallic compound δ phase, and during the cooling, the intermetallic compound θ phase is crystallized on the Al side, This suggests that the strength of the joint (brazing strength) is lowered.

Also, in Patent Document 1, in the case of making a solder ball in which an Al material and a Cu material are bonded together through a brazing material, at least one of the joining portions of the Al material and the Cu material is previously plated with Ni to form a plating layer, A brazing material such as Al-Si or an alloy mainly containing Al-Si is used to solder an Al material and a Cu material.

Patent Document 2 discloses a method of manufacturing a copper alloy member that includes silver (Ag) on a bonding surface of a member made of aluminum (Al) or aluminum (Al) alloy and a member made of copper or a copper alloy, The metal layer is brazed and the metal layer is brazed with a bonding surface of an aluminum (Al) or aluminum (Al) alloy member and an Al-Si based alloy brazing material, A reaction layer in which a metal layer and a region where an intermetallic compound of Al-Ag is generated are formed, and the reaction layer is constituted by reaction of the brazing material, silver (Ag) and aluminum (Al) In which an intermetallic compound of Al-Ag generated in the form of a mesh is made to exist between the member made of aluminum or aluminum alloy and the member made of copper or a copper alloy.

Japanese Patent Application Laid-open No. 56-109157 Japanese Patent No. 3917503

Light metal welding Vol.40 (2002) No.9, p13-20

However, in the non-patent document 1, the fracture behavior of an Al-Cu brazed joint is examined in detail, and the main part of the final fracture position is not an interface between two kinds of other intermetallic compounds, , and the inside of the? phase. In the above non-patent document 1, melting and solidification of the brazing material is necessarily accompanied by the brazing of the aluminum member and the copper member, and therefore it is in principle difficult to control the generation of the intermetallic compound layer to the extent necessary for the improvement of the joint strength . In addition, in the technique disclosed in the above non-patent document 1, vacuum brazed solder is employed, which leads to a drawback that the productivity is low and the cost is high.

Further, in the technique disclosed in Patent Document 1, it is necessary to form a plating layer by Ni plating in advance at the joining portion of at least one of the Al material and the Cu material. In the technique disclosed in Patent Document 2, It is necessary to use silver (Ag), which leads to an increase in cost and a problem in that the process becomes troublesome.

Accordingly, development of a technique for surface brazing solder of an aluminum alloy member and a copper alloy member which does not cause a rise in cost while ensuring stable brazing quality is desired.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above problems, and it is an object of the present invention to provide an aluminum alloy member and a copper alloy member which are capable of suppressing the growth of an intermetallic compound layer when aluminum alloy members and a copper alloy member are brazed in a flux- It is an object of the present invention to provide a technique of surface-brazing excellent in brazing strength (shearing force) while maintaining a high thermal conductivity between an alloy member and a copper alloy member.

In order to attain the object, the method for brazing the aluminum alloy member and the copper alloy member of the present invention comprises 1.0 to 12 mass% of Si and 0.1 to 5.0 mass% of Mg, and the remaining amount of Al and inevitable impurities Wherein the brazing sheet is brazed to the aluminum alloy member and the copper alloy member by using a single layer brazing sheet including a brazing material having a thickness of 15 to 200 mu m, The aluminum alloy member and the copper alloy member are brazed in a flux-less manner while maintaining a brazing temperature of 510 to 550 DEG C while applying a surface pressure of 0.6 MPa or more in an inert gas atmosphere. do.

It is preferable that Cu, Mn, and Zn as inevitable impurities contained in the brazing material are each less than 1.0% by mass.

It is preferable that the brazing material has a thickness of 15 to 150 mu m and a thickness of 15 to 100 mu m.

As the aluminum alloy member to be brazed to the surface, it is preferable that the solidus temperature is at least 520 캜. As the aluminum alloy member, it is more preferable that the solidus temperature is 550 캜 or higher. As the aluminum alloy member, for example, it is more preferable that the solidus temperature is 600 占 폚 or higher like AA1000 series.

The brazing temperature is preferably 510 to 550 ° C.

The holding time at the brazing temperature at the time of surface brazing is preferably 2 minutes or more, particularly 5 minutes or more.

In addition, it is preferable that the inert gas during the surface brazing is nitrogen gas, and the oxygen concentration of the inert gas is preferably 500 ppm or less.

According to the brazing method of the aluminum alloy member and the copper alloy member provided by the present invention, the aluminum alloy member and the copper alloy member are flux-free in an inert gas atmosphere, and the specific surface pressure between the aluminum alloy member and the copper alloy member And then brazed to the surface. As a result, it is possible to suppress void defects and the like which are likely to occur between the aluminum alloy member and the copper alloy member, and consequently, the surface brazing can be performed with stable quality.

According to the surface brazing method, it is possible to braze in an inert gas atmosphere and employ a production method of continuous furnace. Therefore, compared to the case of vacuum brazing with a batch furnace, production efficiency is high, Type brazing sheet is used, the overall cost can be reduced. Further, since brazing is performed by adding a surface pressure of 0.6 MPa or more between the aluminum alloy member and the copper alloy member, the brazing material inserted between the aluminum alloy member and the copper alloy member is efficiently discharged between the aluminum alloy member and the copper alloy member do. This makes it possible to suppress the generation of an intermetallic compound such as a phase in particular on the Al side so that the thickness of the intermetallic compound layer can be reduced and the thermal conductivity between the aluminum alloy member and the copper alloy member can be kept high , And brazing strength (shearing force) are excellent.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.
2 is a view for explaining a shape of a test piece for observing a metal structure and measuring a thermal conductivity.
3 is a conceptual diagram illustrating a shear test method.
4 is a conceptual view for explaining a pressure brazed test jig.
5 is a photograph illustrating the thickness measurement of the intermetallic compound layer.
6 is a view showing the effect of an additional pressure on the thickness of a compound layer during soldering;
7 is a graph showing the influence of the thickness of the compound layer on the shear strength.
8 is a graph showing the influence of the thickness of the compound layer on the thermal conductivity.
9 is a photograph showing a cross-section metal structure at an additional pressure of 0.2 MPa.
10 is a photograph showing a cross-section metal structure at an additional pressure of 0.6 MPa.
11 is a view showing the effect of brazing temperature and holding time.
12 is a diagram showing the influence of the amount of Mg added in the brazing material.
13 is a view showing the influence of the amount of Si added in the brazing material.
14 is a diagram showing the influence of an impurity content in a brazing material.
15 is a view showing the influence of the thickness of the brazing material.
16 is a diagram showing the influence of oxygen concentration in a brazing atmosphere.

Generally, in the case of surface brazing, a brazing material is inserted between an aluminum alloy member to be bonded and a copper alloy member, and brazing heating is carried out, which inevitably involves melting and solidification of the brazing material. That is, as long as the brazing material remains between the aluminum alloy member and the copper alloy member even after brazing, it is difficult to control the generation of the intermetallic compound layer to the extent necessary for improving the strength of the joint. As a result, the quality of the brazed product tends to vary.

In addition, as shown in Patent Document 1, when Ni plating is applied to the joint portion of at least one of the Al material and the Cu material, or when expensive silver (Ag) is used as the insert material as shown in Patent Document 2 The soldering is performed by using the Al-Si alloy soldering material, so that the cost is increased and the process is also troublesome.

Accordingly, the present inventors have reached the present invention in a process of carefully examining a surface brazing method at a low cost and a stable quality as compared with the prior art.

The details will be described below.

First, the present invention is characterized in that a single-layer brazing sheet having a minimum thickness including an Al-Si-Mg alloy brazing material is sandwiched between an aluminum alloy member and a copper alloy member and a specific surface pressure is applied in a state of surface contact, Dissolving the solder material sufficiently while dissolving the interface between the aluminum alloy member and the copper alloy member and actively discharging the melted solder material from the interface to thin the thickness of the intermetallic compound layer formed between the aluminum alloy member and the copper alloy member Possible surface brazing method. Since the thickness of the intermetallic compound layer can be reduced, a joined body having a high brazing strength can be obtained.

The aluminum alloy member may be an aluminum alloy plate or an aluminum alloy extruded material or an aluminum alloy casting. Similarly, the copper alloy member may be a copper alloy plate, a copper alloy extruded material, or a copper alloy cast material. For example, a latching portion may be provided so that a component made of an aluminum alloy and a component made of a copper alloy can be connected to each other, and a portion for fitting the brazing sheet into the latching portion may be provided. In short, in the present invention, the material to be bonded is not limited to an aluminum alloy plate or a copper alloy plate, and any material may be used as long as it is made of an aluminum alloy material and a copper alloy material having at least a smooth brazable surface.

The aluminum alloy member to which the surface brazing method of the present invention is applied preferably includes an aluminum alloy having a solidus temperature of at least 520 캜.

When an Al-Si based brazing material described in detail later is used, a brazing temperature of 510 DEG C or more is required for sufficiently dissolving the brazing material, and the solidus temperature of the aluminum alloy member to be bonded is 520 DEG C Or more. If the solidus temperature of the aluminum alloy member to be bonded is less than 520 캜, there is a possibility that at least a part of the aluminum alloy member is dissolved in the heating of the brazing. More preferably, the solidus temperature of the aluminum alloy member is 550 DEG C or higher. More preferably, the solidus temperature of the aluminum alloy member is 600 占 폚 or higher.

The first feature of the present invention resides in the use of a brazing sheet comprising a soldering material layer having a predetermined composition and thickness to suppress the cost.

Therefore, first, the brazing material will be described.

An aluminum alloy thin plate having a composition of 1.0 to 12% by mass of Si and 0.1 to 5.0% by mass of Si and having a composition of Al and inevitable impurities, and having a thickness of 15 to 200 占 퐉, use.

Si : 1.0 to 12 mass %

Si is an element for reducing the temperature of the liquidus line of the brazing sheet by its content and improving the wettability in the surface brazing. If the Si content is not satisfied by 1.0% by mass, the temperature of the liquidus line of the brazing sheet becomes excessively high, and even if the brazing sheet reaches a predetermined brazing temperature, the brazing sheet becomes insufficient and sufficient brazing strength (shear stress) There is a possibility. On the other hand, when the Si content exceeds 12 mass%, there is a high possibility that the primary Si precipitates (crystallizes) in the central portion of the ingot during casting, and even if a good hot rolled sheet is obtained, it is difficult to obtain a microstructured, It becomes.

Therefore, the Si content in the brazing material is in the range of 1.0 to 12 mass%. The more preferable Si content is in the range of 2.0 to 12 mass%. The more preferable Si content is in the range of 3.0 to 12 mass%.

Mg : 0.1 to 5. 0 mass %

Mg is considered to be an element for suppressing the oxidation of aluminum at the interface between the aluminum alloy member and the brazing material of the brazing sheet by brazing heating because of its own oxidation and thereby reducing the wettability in the surface brazing. If the Mg content is not satisfied at 0.1 mass%, the effect becomes insufficient depending on the brazing temperature and the holding time, and sufficient brazing strength (shear stress) may not be obtained. On the other hand, when the Mg content exceeds 5.0 mass%, the load on the roll at the time of hot rolling the ingot becomes large, and corner cracking also occurs, so that hot rolling becomes difficult. Considering the workability of the brazing material, it is preferable that the Mg content is low.

Therefore, the Mg content in the brazing material is set in the range of 0.1 to 5.0 mass%. A more preferable Mg content is in the range of 0.1 to 4.0 mass%. The Mg content is more preferably in the range of 0.1 to 3.0 mass%.

The remainder portion contains Al and unavoidable impurities.

As the inevitable impurities, Fe, Cu, Mn, Zn and the like can be mentioned. However, these elements are preferably contained in an amount of less than 1.0% by mass of Fe, less than 1.0% by mass of Cu, less than 1.0% by mass of Mn and less than 1.0% Range does not hinder the effect of the present invention. Therefore, the content of the above-mentioned components as the inevitable impurities is preferably less than 1.0% by mass each.

It is also possible to use Cr, Ni, Zr, Ti, V, B, Sr, Sb, Ca and Na as other impurity elements. Less than 0.1% by mass of Ti, less than 0.1% by mass of Ti, less than 0.05% by mass of B, less than 0.05% of Sr, less than 0.05% of Sb, less than 0.05% , The performance characteristics of the brazing sheet according to the present invention are not significantly deteriorated and may be included as inevitable impurities. Pb, Bi, Sn, and In are 0.02 mass% or less and 0.02 mass% or less, respectively, and the presence of the non-controlled element in this range does not hinder the effect of the present invention.

Brazing  Thickness of the brazing material constituting the sheet: 15 to 200 탆

The thickness of the brazing material constituting the single-layer brazing sheet according to the present invention may be a thickness that can achieve sound surface brazing. If the thickness is less than 15 mu m, sufficient brazing strength may not be obtained. If the thickness exceeds 200 占 퐉, the amount of the brazing material discharged from the bonding surfaces becomes excessively large, resulting in a high cost. Therefore, the thickness range of the brazing material is 15 to 200 mu m. A more preferable range of the thickness is 15 to 150 占 퐉. A more preferable thickness range is 15 to 100 占 퐉.

Brazing material  Single layer type Brazing  Method of manufacturing sheet

For example, a single-layer brazing sheet including a brazing material having a thickness of 100 mu m is produced as follows.

An ingot as a raw material, scrap and the like are mixed and charged into a melting furnace, and a molten aluminum containing a predetermined brazing composition is dissolved. The melting furnace is generally a burner which directly melts the raw material by the flame of the burner. After the molten aluminum reaches a predetermined temperature, for example, 800 占 폚, an appropriate amount of flux for slag removal is introduced and the molten metal is stirred by a stirring rod to dissolve all the raw materials. Thereafter, for adjustment of the components, an additional raw material, for example, Mg or the like is added, and the metal scum floating on the surface is removed after sedimentation for about 30 to 60 minutes. After the aluminum molten metal is cooled to a predetermined temperature, for example, 740 占 폚, the molten metal is spouted from the tapping trough to the trough, and casting is started, if necessary, through an in-line rotary degassing apparatus, a CFF filter or the like. In addition, when the melting furnace and the furnace are installed in parallel, the molten metal in the melting furnace is moved to the furnace furnace, and then the furnace is also subjected to soaking and the casting is started.

The jacket of the DC casting machine may be one injection, but it may be a multiple injection which emphasizes production efficiency. For example, the lower mold is lowered at a casting speed of 60 mm / min while pouring through a dip tube and float in a water-cooled mold having a size of 700 mm × 450 mm, and direct cooling The molten metal in the sump is coagulated and cooled to obtain a slab having a predetermined size, for example, a size of 700 mm x 450 mm x 4500 mm. After completion of the casting, the front end and the rear end of the slab were cut to obtain a double-sided surface of 25 mm in length. A slab having a thickness of 400 mm was inserted into the soaking furnace and homogenized at 450 to 540 캜 for 1 to 12 hours ). After the homogenization treatment, the slab is removed from the soaking furnace, and subjected to hot rolling in any pass by a hot rolling mill to obtain a hot rolled sheet coil (Reroll) having a thickness of, for example, 6 mm.

A 6 mm thick hot-rolled sheet coil is cold-rolled in any pass to obtain a single-layered brazing sheet including a brazing material having a predetermined thickness, for example, a thickness of 100 mu m. When the work hardening of the cold rolled plate is remarkable in the cold rolling step, the coil is inserted into the annealer as necessary and subjected to an intermediate annealing treatment at a holding temperature of 300 to 450 DEG C to soften the cold rolled plate .

A second feature of the present invention resides in that a specific surface pressure is added between the aluminum alloy member and the copper alloy member without using flux in an inert gas atmosphere. As a result, when the brazing material is melted, it is efficiently discharged from between the aluminum alloy member and the copper alloy member. In particular, it is possible to suppress the generation of intermetallic compounds such as the? -Phase on the Al side, And the surface brazing can be performed with excellent brazing strength (shearing force) while maintaining a high thermal conductivity between the aluminum alloy member and the copper alloy member.

Under an inert gas atmosphere

As described above, in order to sufficiently dissolve the brazing sheet (brazing material) to wet the interface between the aluminum alloy member and the copper alloy member, brazing must be maintained at least at a holding temperature of 510 DEG C or higher for a predetermined time.

Therefore, in order to suppress the oxidation of the surface of the brazing surface of the aluminum alloy member or the copper alloy member or the brazing material surface of the brazing sheet even during brazing heating, it is necessary to conduct surface brazing under an inert gas atmosphere.

As the inert gas, nitrogen gas, argon gas, helium gas, or the like can be used. The oxygen concentration in the inert gas is preferably 500 ppm or less. If the oxygen concentration in the inert gas exceeds 500 ppm, the bonding strength (shear stress) after surface warping is lowered.

More preferably, the oxygen concentration in the inert gas is 100 ppm. More preferably, the oxygen concentration in the inert gas is 10 ppm or less. Concretely, for the industrial nitrogen gas, since the standard is set at an oxygen concentration of 10 ppm or less, it is most preferable to use industrial nitrogen gas from the viewpoint of cost.

Of course, it is preferable to fill the inside of the heating apparatus in an inert gas atmosphere during brazing heating, during brazing temperature holding, and during cooling. However, in the case of rapid heating such as electromagnetic induction heating, the atmosphere in the heating device may be replaced with an inert gas by injecting an inert gas before reaching a predetermined holding temperature.

addition Surface pressure ; 0.6 MPa or more

In the surface brazing method according to the present invention, a brazing sheet (brazing material) having a predetermined composition is dissolved, and brazing heating is performed in a state in which the brazing material and the aluminum alloy member, the brazing material and the copper alloy member are in surface contact with each other , It is necessary to maintain the soldering temperature at a predetermined value while applying a surface pressure of 0.6 MPa or more to the bonding surface. Needless to say, surface pressure brazing may be performed by adding a surface pressure of 0.6 MPa or more to the bonding surface by a press or the like provided in the furnace immediately before reaching the melting temperature of the brazing material, without applying surface pressure during brazing heating.

When the surface pressure is 0.6 MPa or more, the brazing material inserted between the aluminum alloy member and the copper alloy member is efficiently discharged from the interface between the aluminum alloy member and the copper alloy member when molten. This makes it possible to suppress the generation of an intermetallic compound such as a phase in particular on the Al side. Concretely, for example, the thickness of the intermetallic compound layer can be set to 30 占 퐉 or less, and the surface-brazed solder having excellent brazing strength (shearing force) can be performed while maintaining a high thermal conductivity between the aluminum alloy member and the copper alloy member .

When the surface pressure is less than 0.6 MPa, the brazing material inserted between the aluminum alloy member and the copper alloy member is hardly discharged from the interface between the aluminum alloy member and the copper alloy member even after melting. As a result, the diffusion of Cu atoms from the surface of the copper alloy member into the melted solder material progresses rapidly, and generation of an intermetallic compound such as the? -Phase on the Al side including the brazing material can not be suppressed. As a result, the thickness of the intermetallic compound layer can not be reduced, and the thermal conductivity at the interface between the aluminum alloy member and the copper alloy member is lowered, and sufficient brazing strength (shear stress) can not be obtained. Of course, in order to sufficiently secure the brazing strength (shearing stress) while maintaining the high thermal conductivity of the interface between the aluminum alloy member and the copper alloy member after the surface brazing, it is preferable that the surface pressure added to the bonding surface is high. Therefore, the preferable surface pressure is 0.6 MPa or more. A more preferable surface pressure is 1.0 MPa or more.

Brazed  Temperature condition: maintained at 510 to 550 캜

In the surface brazing method of the present invention, a brazing sheet (brazing material) having a predetermined composition is dissolved to wet the interface between the aluminum alloy member and the copper alloy member, and the melted brazing material is bonded to the aluminum alloy member and the copper alloy In order to reliably perform surface brazing while discharging from the interface of the member, at least the brazing temperature needs to be 510 DEG C or higher.

When the brazing temperature is less than 510 占 폚, the brazing material is insufficiently dissolved, and sufficient brazing strength (shearing strength) is not obtained. Of course, a brazing strength (shear strength) which is more sufficient can be obtained when the holding temperature is higher within an allowable range. However, when the holding temperature exceeds 550 DEG C, the diffusion of Cu atoms into the Al side including the brazing material progresses rapidly, and even when the aluminum alloy member of 1000 series is heated, the solidus temperature near the interface is lowered, And a specific surface pressure is applied to the aluminum alloy member. There is a possibility that the copper alloy member is deeply embedded in the aluminum alloy member. Thus, the preferred holding temperature is in the range of 510-550 占 폚.

Brazed  Retention time

The holding time at the brazing temperature is preferably at least 2 minutes. If the holding time is less than 2 minutes depending on the brazing temperature, sufficient brazing strength (shearing strength) can not be obtained due to uneven temperature on the bonding surfaces. A more preferable holding time is 5 minutes or more.

Example

Brazing  Sheet production

A predetermined variety of ingots were weighed and blended, and 9 kg (total of 16 samples) of raw materials were loaded into a # 30 crucible coated with a release material. These crucibles were inserted into an electric furnace and dissolved at 760 캜 to remove scum, and then the temperature of the molten metal was maintained at 740 캜. Next, nitrogen gas was blown into the molten metal at a flow rate of 1 N / min for 10 minutes by means of a small rotary degassing apparatus, and degassing treatment was carried out. Thereafter, sedimentation was performed for 30 minutes, scum floated on the surface of the molten metal was removed with a stirring rod, and a disc sample was taken in a casting mold for analysis by a spoon.

Subsequently, the crucible was sequentially taken out of the electric furnace by using a jig, and aluminum melt was injected into five metal molds (70 mm x 70 mm x 15 mm) preheated to 200 deg. The disk samples of each sample were subjected to compositional analysis by emission spectroscopic analysis. The results are shown in Table 1.

The ingot was cut in a pressure vessel, and the both surfaces were subjected to machining in 3 mm increments to a thickness of 9 mm. The ingot was charged into an electric furnace, heated to 480 占 폚 at a heating rate of 100 占 폚 / hr, homogenized at 480 占 폚 for 1 hour, and hot-rolled to a thickness of 3 mm by a hot rolling mill .

Thereafter, the hot-rolled sheet was cold-rolled to form a cold-rolled sheet having a thickness of 0.2 mm and subjected to intermediate annealing at 400 ° C for 2 hours to soften it. Further, cold-rolling was performed to obtain a final cold-rolled sheet of 0.06 mm (60 탆). In order to investigate the effect of the brazing material thickness on the brazing strength (shear stress), the E-alloy brazing material was subjected to five levels of final rolled plates of thickness 15 占 퐉, 20 占 퐉, 30 占 퐉, 60 占 퐉 and 100 占 퐉 Respectively.

This final cold-rolled sheet was cut into a predetermined size (15 mm x 8 mm) to obtain a plurality of brazing sheets (brazing materials).

Production of reverse T-test specimen

As shown in Fig. 1, a brazing sheet (15 mm x 8 mm) was placed in the center of a 35 mm x 35 mm plane of a block A (35 mm x 35 mm x 10 mm) made of AA1100, (15 mm x 8 mm) in the block B (18 mm x 15 mm x 8 mm) of the block C1020 was superimposed on the brazing sheet, and the block B (35 mm x 35 mm) Respectively.

Further, a block or the like assembled in the test furnace was inserted while pressing the upper surface of the block B by using a pressurized brazed test jig as shown in Fig. 4 (a). (Nitrogen with an oxygen concentration of 10 ppm or less) is fed at a flow rate of 10 Nl / min in order to replace the atmosphere with an inert gas, the PID control is repeated until the thermocouple provided in the block A exhibits a predetermined brazing temperature. Deg.] C / min, held at a predetermined brazing temperature for a predetermined time, turned off the output to the resistance wire, and cooled the assembled block and the like. After the thermocouple installed in the block A showed 400 DEG C or less, the assembled block or the like was removed from the furnace and cooled to room temperature.

In order to investigate the influence of the oxygen concentration on the brazing strength (shear stress) by the brazing atmosphere, an industrial nitrogen (oxygen of 10 ppm or less in oxygen concentration) was used for the E alloy brazing material (brazing material thickness: In addition, an inverted-T test piece was produced in the same manner under the conditions of nitrogen gas of 500 ppm oxygen, nitrogen of 2000 ppm in oxygen concentration, nitrogen gas, and air atmosphere at a brazing temperature of 540 캜 and a holding time of 10 minutes.

Measurement of Shear Stress

The thus prepared reverse T-shaped test piece was fixed to the jig as shown in Fig. 3, and pressed against the end surface (35 mm x 10 mm surface) of the block A by the arm slider (deformation rate: 1 mm / min) , And the brazing strength (fracture shear stress) on the brazed surface was measured.

Fabrication of test specimens for metal structure observation and thermal conductivity measurement

As shown in Fig. 2, a brazing sheet (30 mm x 30 mm) was placed on the center of a 40 mm x 40 mm plane of block C (40 mm x 40 mm x 4 mm) of AA1050, 30 mm x 30 mm in the block D (30 mm x 30 mm x 2.5 mm) of the block C was placed on the brazing sheet and the block D was placed at the center of the surface of 40 mm x 40 mm in the block C I overlapped.

Further, a block or the like assembled in the test furnace was inserted while pressing the upper surface of the block D by using a pressurized brazed test jig as shown in Fig. 4 (b). (Nitrogen with an oxygen concentration of 10 ppm or less) at a flow rate of 10 Nl / min in order to replace the atmosphere with an inert gas, the PID control is repeated until the thermocouple provided in the block C exhibits a predetermined brazing temperature. Deg.] C / min, held at a predetermined brazing temperature for a predetermined time, turned off the output to the resistance wire, and cooled the assembled block and the like. After the thermocouple installed in block C showed a temperature of 400 DEG C or less, the assembled block was taken out of the furnace and cooled to room temperature.

Measurement of thermal conductivity

The thermal conductivity was calculated by multiplying the density, specific heat, and thermal diffusivity. Density, dimension and weight measurements, specific heat, and thermal diffusivity were measured by laser flash method. The test specimens used for the observation of metal structure and for the measurement of thermal conductivity were processed to a plate thickness of 2 mm with a milling cutter and then finished with a test piece having a diameter of 2 mm by wire cut electric discharge machining. As the laser flash method, TC-7000, a thermo-numerical value measuring device manufactured by Erbilco Co., Ltd. was used.

Intermetallic Compound layer  Measurement of thickness

The center section of a test piece for observation of metal structure and thermal conductivity was embedded in a resin and subjected to mirror polishing, and the thickness of the intermetallic compound layer was measured under a metallurgical microscope as shown in Fig. 5, the upper region is a Cu base (oxygen-free copper (C1020)), and the lower region is an Al base (AA1050 alloy). A delta phase is formed in layers on the upper side and a &thetas; phase in the lower side is generated on the lower side along the bonding interface between these materials. The distance between the delta phase and the Cu substrate (point a) and the distance between the delta phase and the Al substrate (point b) were measured so as to be orthogonal to the bonding interface, Respectively. In this way, the thickness of the intermetallic compound layer was measured at 10 arbitrary sections on one test piece, and the average value was defined as the thickness of the compound layer.

In the description of the above embodiments, E-alloy brazing material (brazing material thickness: 60 탆) and the material to be bonded (block of AA1100 alloy and oxygen-free copper (C1020) And brazing was performed under the conditions of a brazing temperature of 540 占 폚, a holding time of 10 minutes, and a pressing force of 3 MPa while nitrogen for industrial use (nitrogen of 10 ppm or less in oxygen concentration) was flowing to prepare an inverted T type test piece and a thermal conductivity And a test piece for measurement was produced.

The results are shown in Tables 2 to 10 and Figs. 6 to 16.

First, from the results shown in Table 2, it can be understood that brazing is performed while adding a surface pressure of 0.6 MPa or more, whereby the thickness of the compound layer is 30 μm or less. As for the influence of the thickness of the compound layer on the shear strength, it can be seen that the shear strength increases when the thickness of the compound layer is 30 탆 or less. As for the influence of the compound thickness on the thermal conductivity, it can be seen that the thermal conductivity increases when the thickness of the compound layer is 30 탆 or less. In addition, a photograph of a cross-sectional structure with respect to the influence of the additional pressure at the time of soldering on the thickness of the compound layer shows that when brazing is performed while applying a surface pressure of 0.2 MPa, the intermetallic compound such as the? However, when brazing is performed while adding a surface pressure of 0.6 MPa, the intermetallic compound such as the? -Phase does not greatly grow on the Al side, and the structure becomes thin and has a substantially constant thickness, Is suppressed.

Therefore, it is understood that it is preferable to add a surface pressure of 0.6 MPa or more to the additional pressure during soldering.

As for the brazing temperature, it is understood that it is preferable to be 510 DEG C or more. It is also understood that the brazing temperature holding time is preferably 2 minutes or more, particularly preferably 5 minutes or more.

Next, regarding the influence of the components in the aluminum alloy constituting the brazing material, it is sufficient to contain 0.1 mass% of Mg in order to obtain a desired shear stress when soldering at 540 캜. However, when the Mg content is less than 0.01 mass% when brazed at 540 캜, desired shear stress is not obtained. In the case where the Mg content exceeds 3.0% by mass, the shear stress is not lowered even by brazing at 540 占 폚, but the workability of the brazing material itself deteriorates as described above. Therefore, the preferable content of Mg is 0.1 to 3.0 mass%.

With respect to the Si content, a sufficient shear stress is obtained in the range of 1.0 to 12.0 mass%, but when the Si content is 0.5 mass%, the obtained shear stress is slightly lower.

Therefore, the preferable content of Si is 1.0 to 12.0 mass%.

It is understood that Cu, Mn and Zn, which are inevitable impurities, have almost no influence on the shear stress if they are each contained in an amount of less than 1.0% by mass.

With respect to the thickness of the brazing material, if the thickness is 15 m or more, sufficient shear stress is first obtained, but when the thickness is 15 m, the obtained shear stress is slightly lower. Therefore, it is preferable that the thickness of the brazing material is 15 mu m or more. If the thickness is excessively large, the brazing material becomes excessively large, so that the upper limit is 200 mu m as described above.

As for the atmosphere during brazing, it is understood that the atmosphere should be at least an inert atmosphere such as nitrogen. It is preferable that the atmosphere is an inert gas atmosphere having an oxygen content of 500 ppm or less.

According to the present invention, there is provided a technique of surface brazing an aluminum alloy member and a copper alloy member that does not cause a rise in cost while ensuring stable brazing quality.

Claims (9)

Layer brazing sheet comprising a brazing material having a composition of 1.0 to 12 mass% of Si and 0.1 to 5.0 mass% of Si and a balance of Al and inevitable impurities and having a thickness of 15 to 200 占 퐉 A method of brazing an aluminum alloy member and a copper alloy member by surface brazing,
The brazing sheet was sandwiched between the aluminum alloy member and the copper alloy member so that the aluminum alloy member and the copper alloy member were in surface contact with each other while maintaining the brazing temperature at 510 to 550 캜 under an inert gas atmosphere, And the copper alloy member is brazed to the surface of the aluminum alloy member and the copper alloy member. The brazing method as claimed in claim 1, wherein Cu as an inevitable impurity contained in the brazing material is limited to less than 1.0% by mass. The method of brazing an aluminum alloy member and a copper alloy member according to claim 1, wherein Mn as an inevitable impurity contained in the brazing material is limited to less than 1.0% by mass. The brazing method as set forth in claim 1, wherein Zn as an inevitable impurity contained in said brazing material is limited to less than 1.0 mass%. The brazing method as claimed in claim 1, wherein the brazing material constituting the brazing sheet has a thickness of 15 to 150 탆. The brazing method as claimed in claim 1, wherein the holding time at the brazing temperature is not less than 2 minutes. The method of brazing the aluminum alloy member and the copper alloy member according to claim 1, wherein the holding time at the brazing temperature is not less than 5 minutes. The method of brazing an aluminum alloy member and a copper alloy member according to claim 1, wherein the inert gas is a nitrogen gas. The method of brazing an aluminum alloy member and a copper alloy member according to claim 1, wherein the inert gas has an oxygen concentration of 500 ppm or less.

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