JPS6216752B2 - - Google Patents

Description

[Detailed description of the invention]

This invention eliminates the occurrence of cracks caused by the intrusion of solder into the grain boundaries of the base metal to be brazed (hereinafter referred to as base metal cracks due to solder intrusion), and has good wettability, low vapor pressure, and low melting point. The present invention relates to a Cu-Ag alloy brazing filler metal having the following characteristics. Conventionally, in brazing electron tubes and vacuum equipment, for example, when the brazing material is exposed to a vacuum brazing atmosphere, if the amount of component evaporation is large, it contaminates the parts to be brazed and the inner wall of the vacuum brazing furnace, making it difficult to use the material further. Even if the brazed parts are exposed to high temperatures in a vacuum, it will not only reduce the degree of vacuum inside the electron tube or vacuum equipment, but also contaminate the inside of the components, so a brazing filler metal with a low vapor pressure is used. ing. A typical brazing filler metal with low vapor pressure of this type has a composition consisting of Cu: 27 to 29%, Ag, and the remainder of unavoidable impurities (all percentages by weight and percentages below mean weight percent). Ag-Cu alloy brazing filler metal (JIS/BAg-8) is known. However, when this Ag-Cu alloy brazing filler metal with a low vapor pressure is used for brazing base metals of Ni-Fe alloys or Kovar-type alloys, the components of the brazing filler metal may A phenomenon appears in which wax tends to penetrate into the grain boundaries of the material, and as a result, cracks often occur in the base material during or after brazing due to penetration of the wax. Therefore, the above
When brazing base metals made of Ni-Fe alloys or Kovar-type alloys, the Ag-Cu alloy brazing filler metal is used to suppress the intrusion of constituent components of the brazing filler metal into the grain boundaries of the base metal.
Ag-Cu-Pd alloy brazing filler metal containing 5 to 25% Pd is used to prevent cracks caused by penetration of solder into the base metal.
In the case of alloy brazing filler metals, the melting point increases in proportion to the Pd content, and the wettability also deteriorates, so it cannot necessarily be said that they are brazing filler metals with good brazing properties. From the above-mentioned viewpoint, the present inventors focused on the conventional Ag--Cu--Pd alloy brazing material, and conducted research to lower the melting point of this brazing material and improve its wettability. This Ag-Cu-Pd alloy brazing filler metal
When Si is added, there is no cracking of the base material due to solder penetration, and the melting point is lowered while maintaining a low vapor pressure, and the wettability is also significantly improved. , Sn and In, the melting point of the brazing filler metal is further lowered and the wettability is further improved without impairing the property improvement by Si. If you do the above
In addition to improving the strength of the brazing filler metal without impairing the property improvements brought about by Si, the intrusion of constituent components of the brazing filler metal into the grain boundaries of the base material is further suppressed. When B and Li are included, these components have a significant deoxidizing effect, which not only prevents the oxidation of the wax during brazing, but also significantly suppresses the dissolution of gas into the molten solder. I gained knowledge. This invention was made based on the above findings, and includes: Ag: 25-65%, Pd: 0.5-25%, Si: 0.25-6.5%, one or two of Sn and In: 1 ~Ten
%, and if necessary, one or more of Fe, Ni, and Co: 1 to 10%, and further, if necessary, one or more of B and Li. Type 2: Contains 0.001 to 0.8%, Cu and unavoidable impurities: the remainder, and has a low vapor pressure and low melting point, and exhibits good wettability during brazing. This is a Cu-Ag alloy brazing filler metal that does not cause base metal cracking due to penetration. Next, the reason why the composition range of the Cu--Ag alloy brazing material of the present invention is limited as described above will be explained. (a) Ag The Ag component has the effect of lowering the melting point of the brazing filler metal and improving its wettability when coexisting with Cu and Si components, as well as improving the processability of the brazing filler metal into foil and ultrafine wire. If the content is less than 25%, the desired effect cannot be obtained in the above-mentioned action, and on the other hand, even if the content exceeds 65%, the effect of further improvement in the action cannot be obtained. its content 25-65%
It was determined that Note that when performing cold working under severe conditions, an Ag content of 35% or more is desirable. (b) Pd The Pd component has the effect of suppressing the intrusion of brazing components into the grain boundaries of the base material during brazing, especially when the component to be brazed is a Ni-Fe alloy or Kovar type alloy. However, if the content is less than 0.5%, the desired effect cannot be obtained, while if the content is less than 0.5%, the desired effect cannot be obtained.
If the content exceeds 20%, the melting point of the brazing material will increase,
The content was set at 0.5 to 25% because it also deteriorated the wettability. (c) Si The Si component has the effect of significantly improving the wettability and lowering the melting point without affecting the vapor pressure of the brazing filler metal, but if its content is less than 0.25%, the above effect will not be achieved. Not getting the desired effect, while 6.5
If the content exceeds 0.25%, the processability of the brazing filler metal will deteriorate.
It was set at 6.5%. Note that if it is necessary to perform cold working under severe conditions, a Si content of 5% or less is desirable. (d) Sn and In These components have the uniform effect of further lowering the melting point of the brazing filler metal and further improving the wettability, but if their content is less than 1%, the desired improvement effect on the above effects may not be achieved. However, if the content exceeds 10%, the workability of the brazing filler metal deteriorates, so the content was set at 1 to 10%. (e) Fe, Ni, and Co These ingredients improve the strength of the brazing filler metal without reducing its ductility, and they also improve the strength of the brazing filler metal without reducing its ductility. In some cases, high strength from the brazing filler metal is required, as it has a uniform effect of suppressing the intrusion of the brazing filler metal constituents into the grain boundaries of the base material during brazing.
It is included as necessary when it is necessary to further suppress the intrusion of brazing material constituents into the base metal grain boundaries during brazing, but if the content is less than 1%, the desired improvement effect cannot be obtained. On the other hand, if the content exceeds 10%, the processability of the brazing filler metal will deteriorate and the melting point will also rise, so the content should be reduced to 1%.
It was set at ~10%. (f) B and Li These components prevent oxidation of the solder during soldering, forcefully reduce oxides on the surface of the soldering base material, and significantly suppress the dissolution of gas into the molten solder. Since it has equivalent effects, it is included as necessary when these effects are required, but if its content is less than 0.001%, the desired effect cannot be ensured; %
If the content exceeds 0.001 to 0.8, the processability of the brazing filler metal will deteriorate.
%. Next, the Cu--Ag brazing filler metal of the present invention will be explained using examples and in comparison with conventional examples. Examples Brazing fillers 1 to 26 of the present invention and conventional brazing fillers 1 to 4 having the compositions shown in Table 1 were manufactured by applying ordinary melting and plastic working methods. Next, the brazing filler metals 1 to 26 of the present invention obtained as a result
and conventional brazing filler metals 1 to 4, JIS/Z3191
Kovar alloy (Ni: 29%, Co:
17%, Fe and unavoidable impurities: remainder) The spread area of the wax on the base material was measured. Also, in the same argon atmosphere, the above brazing filler metal was placed on the above base metal and the temperature was maintained at 850°C for 2 minutes, and then the penetration depth of the brazing filler metal into the base metal grain boundaries was measured. did. In addition, in this solder penetration depth measurement, since conventional brazing filler metals 2 and 3 have high melting points, their heating temperatures were set to 900℃ (conventional filler metal 2) and 950℃, respectively.
℃ (conventional brazing filler metal 3). Further, the vapor pressure at a temperature of 500° C. of the wax (in the same state as after brazing) after measuring the spreading area of the wax was measured.
These measurement results are summarized in Table 1. From the results shown in Table 1, it can be seen that the brazing filler metals 1 to 1 of the present invention
In addition to having low vapor pressures equivalent to those of conventional brazing filler metals 1 to 4, No. 26 exhibits excellent properties equivalent to or better than conventional brazing filler metal 3, in which penetration of the solder into the grain boundaries of the base material is extremely small. It is also clear that it has a low melting point equivalent to conventional brazing fillers 1 and 4, and exhibits good wettability equivalent to or better than conventional brazing filler metal 4, which has good wettability.

【table】

[Table] As mentioned above, the Cu-Ag alloy brazing filler metal of the present invention has extremely small intrusion of the solder into the grain boundaries of the base material during brazing, and has good wettability, low vapor pressure,
It has a low melting point and excellent workability, so brazing can be performed in good conditions without being restricted by the material and shape of the parts to be brazed, and the resulting brazing It has industrially useful properties such as exhibiting stable performance over a long period of time.

Claims (1)

[Claims] 1 Ag: 25-65%, Pd: 0.5-25%, Si: 0.25-6.5%, one or two of Sn and In: 1-10
%, with the remainder consisting of Cu and unavoidable impurities (weight % or more). 2 Ag: 25-65%, Pd: 0.5-25%, Si: 0.25-6.5%, one or two of Sn and In: 1-10
%, and further contains one or more of Fe, Ni, and Co: 1 to 10%, and the remainder is Cu and unavoidable impurities (weight %). Low melting point Cu-Ag alloy brazing filler metal with good wettability. 3 Ag: 25-65%, Pd: 0.5-25%, Si: 0.25-6.5%, one or two of Sn and Tn: 1-10
%, and one or two of B and Li: 0.001~
A low melting point Cu--Ag based alloy brazing filler metal with good wettability, characterized in that it contains 0.8% and the rest consists of Cu and unavoidable impurities (by weight). 4 Ag: 25-65%, Pd: 0.5-25%, Si: 0.25-6.5%, one or two of Sn and In: 1-10
%, and further contains one or more of Fe, Ni, and Co: 1 to 10%, and one or two of B and Li: 0.001 to 10%.
A low melting point Cu--Ag based alloy brazing filler metal with good wettability, characterized in that it contains 0.8% and the rest consists of Cu and unavoidable impurities (by weight).