JPH0716789A - Production of active silver brazing filler metal - Google Patents

Abstract

PURPOSE:To prevent the breakage of the active silver brazing filler metal even if this brazing filler metal is worked to an extremely slender band material or wire by dissolving raw materials for the active silver brazing filler metal contg. a specific ratio of Cu and subjecting the molten metal to rapid solidifying while heating and maintaining the raw materials to and at a specific temp. CONSTITUTION:The raw materials for the active silver brazing filler metal consisting of 25 to 30wt.% Cu, 0.5 to 4% one or >=22 kinds among Ti, Hf, Zn, Zr, Be and Li and the balance Ag and inevitable impurities are dissolved in a vacuum atmosphere, inert gaseous atmosphere or reducing gaseous atmosphere. While the molten metal is heated and held to and at 1350 deg.C, more preferably 1400 to 1800 deg.C, the molten metal is kept stirred just before tapping. The melt of the active silver brazing filler metal is rapidly solidified at >=100 deg.C/sec cooling rate. As a result, an active silver brazing filler metal ingot having the Cu-M intermetallic compd. of finer particle sizes is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an active silver brazing material for brazing ceramics to ceramics, ceramics to metal, or metal to metal, and particularly, the maximum grain size in the matrix is 50 μm. Or less, preferably Cu-M of 30 μm or less (where M is Ti, H
f, Zn, Zr, Be, and Li) (one or more of f, Zn, Zr, Be, and Li) having a structure in which intermetallic compound particles are dispersed. Oxygen content: 100 ppm or less is there.

[0002]

2. Description of the Related Art Generally, Ag is the main component, and C
An active Ag brazing material containing u: 10 to 40% by weight and Ti: 0.5 to 10% by weight is known, and the active Ag brazing material includes Cu powder, Ti powder, and Ag powder as raw material powders. Sintered by powder metallurgy, and finally processed into a strip or a wire to obtain a product. The active Ag brazing material thus produced is widely used for brazing ceramics and ceramics, ceramics and metal, or metal and metal used in electronic or electric parts. (If necessary, refer to JP-A-64-53795, Welding Society Papers Vol. 9 (1991) No. 4, P495-501, etc.).

[0003]

However, the active Ag brazing filler metal produced by the powder metallurgy method contains a large amount of gas components such as oxygen and hydrogen, and is used for brazing of components of electronic or electric parts. When it is used, the gas in the active Ag brazing material is released, the strength of the brazing part varies, and there is a problem that it cannot be applied to products requiring reliability.

Therefore, Cu: 10 to 40% by weight, T
i: 0.5 to 10% by weight, balance: active Ag consisting of Ag
A brazing material is melt-cast in a vacuum atmosphere, an inert gas atmosphere or a reducing gas atmosphere to produce an ingot, and the ingot is rolled to process the active Ag brazing material into a thin strip or a thin wire. Although an active Ag brazing filler metal may be produced by this method, since a coarse particle of Cu—Ti intermetallic compound exceeding 50 μm is generated in the base material of the ingot obtained by the casting, a thin strip material is produced. Or it may be cut each time when processing into a thin wire.
It is difficult to process into a strip material or fine wire with a thickness of less than μm, and even if it is possible, since coarse particles of Cu-Ti intermetallic compound exceeding 50 μm are contained in the base material, the strip material or fine wire is supplied from the reel. Since it may be cut during the process, it is impossible to supply a thinner strip-shaped active Ag brazing material or a thin linear active Ag brazing material that can cope with the recent miniaturization of electronic or electric parts.

[0005]

Therefore, the present inventors have
From this point of view, the activated Ag brazing filler metal ingot is not cut even if it is processed into a thin strip or a thin wire, and the obtained thin strip or thin wire-shaped active Ag brazing filler is used for ceramics, ceramics, and ceramics. As a result of conducting research to obtain an active Ag brazing material that exhibits excellent brazing performance when brazing metal and metal or metal and metal, (1) Cu: 10 to 40 wt%, Ti, H
One or more of f, Zn, Zr, Be and Li (hereinafter referred to as M): The oxygen concentration contained in the active Ag brazing material containing 0.5 to 4% by weight is reduced to 100 ppm or less. For this, it is necessary to dissolve in a vacuum atmosphere, an inert gas atmosphere or a reducing gas atmosphere. (2) Melt in such an atmosphere, and obtain the molten metal at a temperature of 1350 ° C. or higher (preferably 1400 ° C. or higher). While maintaining the temperature at about 1800 ° C.), the mixture is stirred until just before tapping, and then this activated silver brazing filler metal is heated at 100 ° C./sec. When rapidly solidified at the above cooling rate, an active Ag brazing filler metal ingot in which the particle diameter of the Cu-M intermetallic compound is made fine is obtained, and even if this active Ag brazing filler metal ingot is processed into a thin thin strip or wire rod. It was found that a thinner and thinner active Ag brazing material can be obtained without cutting.

The present invention has been made on the basis of such findings, and Cu: 25 to 30% by weight, M: 0.
A molten metal obtained by melting an active silver brazing material having a composition of 5 to 4% by weight and the balance of Ag and unavoidable impurities in a vacuum atmosphere, an inert gas atmosphere or a reducing gas atmosphere. While maintaining the temperature at 1350 ° C. or higher (preferably 1400 to 1800 ° C.) until just before tapping, and then adding 100 parts of this activated silver brazing filler metal melt.
° C / sec. Cu which is rapidly solidified at the above cooling rate:
25 to 30% by weight, M: 0.5 to 4% by weight, O ₂ : 10
A structure that contains 0 ppm or less and the balance is Ag and inevitable impurities, and Cu-M intermetallic compound particles having a maximum particle size of 50 μm or less (preferably 30 μm or less) are dispersed in the base material. It is characterized by a method for producing an active silver brazing material having

Next, the reason why the method for producing the active Ag brazing material of the present invention is limited as described above will be explained.

(1) Cu The active Ag brazing material of the present invention uses Ag-27.5% by weight Cu, which is a eutectic composition of an Ag-Cu alloy, as a standard, and the Cu component is slightly larger than the eutectic composition. Even if it is deviated, it has little effect on the melting point and therefore does not affect the brazing temperature, but if Cu is less than 25% by weight or exceeds 30% by weight, the brazing temperature rises, which is not preferable.
The u content was set to 25-30% by weight.

(2) M (Ti, Hf, Zn, Zr, B
e, one or more of Li) M is added as an essential element because it reacts with ceramics during brazing to form a diffusion layer and thereby joins with the other metal or ceramics. However, if its content is less than 0.5% by weight, the brazing strength becomes insufficient, while if it exceeds 4% by weight, the Cu-M intermetallic compound particles in the brazing material become coarse and their amount also increases. Too much,
The diffusion of M is slowed during brazing, and Cu-M intermetallic compound particles remain on the brazing surface after brazing, which lowers the brazing strength and increases variations in the brazing strength, which is not preferable. Therefore, the M content is set to 0.5 to 4% by weight.

(3) If the melting atmosphere O ₂ is contained in the active Ag brazing filler metal of the present invention in an amount exceeding 100 ppm, O ₂ gas is released during brazing, and fine pores are generated in the brazing portion. It is not preferable because it lowers the brazing strength and increases the variation in brazing strength. Therefore, O contained in the active Ag brazing filler metal
₂ Content must be 100ppm or less, but O
_{2 In} order to reduce the content to 100 ppm or less, it is necessary to dissolve the raw material metal or alloy in a vacuum atmosphere, an inert gas atmosphere or a reducing gas atmosphere.

(4) Melting temperature and agitation M is almost dispersed as Cu-M intermetallic compound particles in the brazing filler metal base, but when the melting temperature is less than 1350 ° C., the maximum particles of Cu-M intermetallic compound are present. The melting temperature was set to 1350 ° C. or higher because the diameter exceeds 50 μm and coarsens. Also, if there is no stirring during dissolution, Cu-
The maximum particle size of the M intermetallic compound exceeds 50 μm and becomes coarse, which is not preferable. Therefore, it is preferable to use a melting furnace accompanied by stirring, such as a vacuum furnace, an inert gas atmosphere furnace, or a reducing gas furnace, for melting the brazing material. However, in the method for producing an active Ag brazing filler metal according to the present invention, the temperature during melting with stirring is 1400 to
Most preferably, it is within the range of 1800 ° C.

(5) Cooling rate Even if the temperature at the time of melting is maintained at 1350 ° C. or higher while stirring, if the cooling rate at the time of casting is slow, Cu-M having a large particle size is generated during solidification in the mold. Since the intermetallic compound is precipitated and casting defects such as shrinkage cavities occur, the cooling rate is 100 ° C./sec. Determined above.

When the structure of the ingot of the active Ag brazing material obtained under the above conditions was examined, it was found that Cu, which was fragile in the casting base, was found.
-M intermetallic compound particles were precipitated and dispersed, and the maximum particle size was 50 µm or less. In this way, the activated Ag brazing filler metal ingot obtained under the above conditions has a maximum particle size of 50 even if Cu-Ti intermetallic compound particles are precipitated and dispersed.
Since it is less than μm, it is not cut even if it is processed into a thin strip material or a thin wire material of less than 50 μm. The Cu-T
The finer the maximum particle diameter of the i intermetallic compound particles, the better, and it is more preferable that the maximum particle diameter is 30 μm or less. In this case, it is more preferable that particles having a particle diameter of 20 to 30 μm do not exceed 50 particles / mm ² and are not dispersed in the Ag brazing material casting base material.

[0014]

EXAMPLES Next, the present invention will be specifically described based on Examples. Pure Cu, pure Ti, and pure Ag were prepared as raw materials, and these raw material metals were weighed so as to have the compounding amounts shown in Tables 1 to 4, then charged into a melting furnace, and shown in Tables 1 to 4. It is heated and melted in the atmosphere and at the temperature, and the molten metal heated to this temperature is continuously stirred until just before tapping. Immediately after stirring, the inner side is vertical: 5 to 50 mm, width: 100 mm, length: 20
Cast in multiple molds of different depth having a dimension of 0 mm,
Solidified at various cooling rates shown in Tables 1 to 4,
I got a casting ingot. The cooling rate was adjusted by changing the wall thickness of the cast ingot, the material of the mold, the thickness of the release agent, the water supply amount of water cooling, and the like.

The ingot thus obtained is hot-rolled at a temperature of 700 ° C. to produce a hot-rolled plate having a thickness of 2 mm, and then the hot-rolled plate is annealed at a temperature of 700 ° C. Then, after the surface cutting, cold rolling and annealing are repeatedly performed until the thickness becomes 50 μm, and the present invention brazing material manufacturing methods (hereinafter, referred to as the present invention method) 1 to 23, comparative brazing material manufacturing method (hereinafter, comparative method) 1 to 8 and a conventional brazing material manufacturing method (hereinafter, referred to as a conventional method) 1.

For comparison, the average particle size is 30 μm.
The Ti powder and the Ag-Cu powder are prepared, and these powders are Cu: 27.5 wt%, Ti: 1.5 wt%, and the rest A
kneaded sufficiently to obtain g, thickness: 15 mm, width: 150
mm, length: 300 mm, a compact having a size of 50 μm was produced by sintering the compact at a temperature of 700 ° C.
The conventional method 2 was implemented by repeatedly performing cold rolling and annealing until it became.

The maximum particle size and oxygen content of the Cu--Ti intermetallic compound dispersed in each matrix of the brazing filler metals obtained by the present invention methods 1 to 23, comparative methods 1 to 8 and conventional methods 1 and 2. Was measured, and the measurement results are shown in Tables 1 to 4.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

From the results shown in Tables 1 to 4, the brazing filler metals obtained by the methods 1 to 23 of the present invention are more dispersed in the brazing filler metal base than the brazing filler metal obtained by the conventional method 1.
It can be seen that the maximum particle size of the Ti intermetallic compound is also extremely fine. Further, the brazing materials obtained by the methods 1 to 23 of the present invention have substantially the same maximum particle size of the Cu-Ti intermetallic compound dispersed in the brazing material base as compared with the brazing material manufactured by the conventional method 2 by the powder metallurgy method. However, it can be seen that the oxygen content is remarkably low.

Further, the brazing filler metals obtained by the comparative methods 1 to 8 under the conditions deviating from the conditions of the present invention have a coarse maximum grain size of the Cu--Ti intermetallic compound and an oxygen content by the powder metallurgy method. It is almost the same as the obtained brazing material,
It is also understood that at least one unfavorable characteristic appears, because some may be cut when being processed into a linear shape.

As described above, according to the method for producing an active silver brazing filler metal of the present invention, a brazing filler metal superior to the conventional one can be provided, which can greatly contribute to the industrial development.

Claims (2)

[Claims] 1. Cu: 25 to 30% by weight, Ti, Hf,
One or more of Zn, Zr, Be and Li:
An active silver brazing material having a composition of 0.5 to 4% by weight and the balance of Ag and inevitable impurities was dissolved in a vacuum atmosphere, an inert gas atmosphere or a reducing gas atmosphere to obtain While the molten metal was heated and held at a temperature of 1350 ° C. or higher, the molten metal was stirred until just before tapping, and then this activated silver brazing filler metal was heated at 100 ° C./sec. A method for producing an active silver brazing material, which comprises rapidly solidifying at the above cooling rate. 2. The molten silver brazing filler metal is heated to a temperature of 1400 to 1
While maintaining the temperature at a predetermined temperature within the range of 800 ° C., stirring was carried out until just before tapping, and then the activated silver brazing filler metal melt heated at this temperature was heated at 100 ° C./sec. The method for producing an active silver brazing filler metal according to claim 1, wherein the rapid solidification is performed at the above cooling rate.