RU2374056C1 - Solder metal for soldering - Google Patents

Abstract

FIELD: electric engineering.

SUBSTANCE: invention can be used when soldering various elements of electronics items made from oxide dielectric materials to each other or to elements made from metals, and namely from copper or their alloys, and first of all elements of electrovacuum SHF items. Solder metal is obtained when melting initial components with the following ratio, wt %: germanium 7-12.5, manganese 0.08-1.2, gallium 0.05-0.5, and copper - the rest.

EFFECT: improving reliability of soldered connection, enlarging functional capabilities at maintaining economy of precious metals.

2 cl, 1 tbl, 5 ex

Description

The invention relates to technological processes, namely to soldering various materials of electronic equipment and, above all, elements of microwave electric products.

The further development of electronic equipment, including microwave electronic equipment, makes special demands both on the reliability of the soldered joints of the elements of microwave products at a given operating temperature, and on the composition of the solders used in them, since they affect, first of all, their thermomechanical characteristics and, hence the output power of the microwave.

When soldering elements of microwave electric vacuum products, hard solders are widely used, containing for the most part a significant amount of precious metals such as gold, platinum, silver, palladium, which determine low vapor pressure, good ductility, wetting ability and fluidity.

One of the characteristics of the solder is a margin in melting temperature, which allows for the implementation of subsequent multistage rations due to manufacturing technology.

Known brazing alloy based on copper [1], containing nickel, tin, phosphorus and one or more surface-active additives from the following elements of the periodic system - gallium, indium, bismuth, lead, cadmium, zinc in the following ratio, wt.%:

Nickel 5-20 Tin 2-10 Phosphorus 10-15 Surfactant additives 0.01-0.5 Copper rest

This solder has limited functionality - it is used only for soldering metals.

In addition, some of these surface-active components are undesirable, while others are unacceptable when soldering vacuum compounds of dielectric materials with metals.

Known brazing alloy also based on copper, containing gold in an amount of 35 wt.% [2]. Due to the combination of copper and gold having sufficiently high melting points, 1083 ° С and 1063 ° С, respectively, this solder also has a high melting point and, therefore, a sufficient margin in melting temperature, which makes it possible to carry out subsequent multistage rations, as described above due to the technology of manufacturing electronic products.

However, this solder, due to the ductility of both copper and gold, as well as their close melting points, has ductility and good wetting ability, as well as low fluidity, but only with respect to metals.

In addition, this solder:

firstly, unsuitable for soldering non-metallic dielectric materials due to

a) the practical absence of their wetting,

b) their low chemical activity;

secondly, and this is important, it has a high content of precious metal - gold.

Known brazing alloy also based on copper (prototype [3]) and containing germanium and manganese in the following ratio of components, in wt.%:

Germanium 5-12 Manganese 0.1-1.5 Copper rest

Germanium in this solder behaves as an alloying component and thereby provides a given melting point of the solder.

Manganese, which in this solder behaves as a chemically and interphase-active element, provides solder activity as a whole and thereby allows soldering metals with both metallized and non-metallized dielectric materials.

In addition, as mentioned above, and it is important, this solder does not contain precious metals.

However, this solder:

firstly, it has a non-eutectic composition and, as a result, its crystallization interval is close to critical, approximately equal to 50 ° С, which can lead to undesirable processes of dissolution of the metal component of the product elements during soldering in solder and, as a result, a decrease in reliability as soldered joints, and the product as a whole;

secondly, it has limitations in terms of functionality:

a) as from the point of view of the materials used in the solder joint,

b) the medium in which the soldering is carried out - only high vacuum, pressure no worse than 1.33 × 10 ^-3 Pa or acutely dried hydrogen with a dew point temperature of no more than -35 ° С.

The technical result of the proposed invention is to increase the reliability of the solder joint, expanding functionality while maintaining the economy of precious metals.

The specified technical result is achieved by the proposed solder for soldering based on copper, germanium and manganese.

In which additionally introduced gallium in an amount of 0.05-0.5 wt.% In the following ratio of starting components, wt.%:

Germanium 7-12.5 Manganese 0.08-1.2 Gallium 0.05-0.5 Copper rest

When soldering oxide dielectric materials with each other or with metals and their alloys, as well as copper with other metals and their alloys, the solder has the following composition, wt.%: Germanium 8.5-9.5, manganese 1-1.2, gallium 0.05-0.07, the rest is copper.

Disclosure of the invention

The presence in the composition of the proposed solder gallium of the specified amount and in combination with other components due to the fact that it has a low melting point, 29.9 ° C, provides a reduction:

firstly, the melting point of the solder by at least 10 ° C, which is a significant technological factor, which is especially important, for example, for soldering dielectric materials with copper, as this reduces the risk of dissolution of copper in the solder and, therefore, increases solder joint reliability

secondly, the temperature range of crystallization of solder on average 5-10 ° C,

thirdly, it suppresses the appearance of a brittle copper-germanium phase in solder, which worsens ductility.

It should be emphasized that even a slight change in the temperature range of solder crystallization leads to a limitation of undesirable dissolution processes in the solder of the metal component of the material of the product elements and, therefore, to an increase in the reliability of both the solder joint and the structure as a whole.

The presence of gallium, due to the fact that in the proposed solder it behaves as a surface-active element, provides an improvement:

firstly, the fluidity of the solder and thereby the improvement of soldering conditions by capillary gaps;

secondly, its wetting ability and, therefore, increased adhesion of solder to the brazed materials of the compound.

Both of these provide increased solder joint reliability.

That is, we can say that gallium from the point of view of its determining role in solder with respect to its properties such as low vapor pressure, ductility, behaves similarly to precious metals, such as gold.

Moreover, the presence of gallium in solder in combination with copper improves mechanical strength, ductility and increases its resistance to corrosion.

The presence in the proposed solder for soldering:

- Germany less than 7 wt.% is undesirable, since its main function in the solder may be violated - providing a given melting interval, and more than 12.5 is unacceptable, since it leads to the appearance of a brittle copper-germanium phase in the solder, worsening plasticity, and therefore , reduce the reliability of the solder joint,

- manganese less than 0.08 is inefficient, and more than 1.2 is unacceptable, since, firstly, it leads to an increase in the melting interval of the solder, to an increase in the concentration of manganese on the surface of the solder and thereby a sharp deterioration of the technological conditions of soldering, and especially in a gaseous environment; secondly, to an increase in the vapor pressure of solder;

- gallium less than 0.05 is ineffective, and more than 0.5 leads to an undesirable increase in the melting interval and thereby to a deterioration of the technological conditions of soldering, and therefore, a decrease in the reliability of the soldered joint.

The proposed both qualitative and quantitative composition of the solder will expand the functionality, namely:

- to connect with metals of both metallized and non-metallic dielectric materials, including oxide ceramic materials,

- soldering in high vacuum, not only in sharply dried hydrogen with a dew point temperature of not more than -35 ° C, but simply in hydrogen, an inert gas, such as purified argon.

It should be noted that oxide ceramic materials are most widely used in microwave electric and vacuum electronic microwave devices.

So, as follows from the above, the proposed solder for soldering will provide increased reliability of the soldered joint and the expansion of functionality.

Examples of specific performance of the proposed solder for soldering.

Example 1

Take samples of Germany GOST-16153-70, manganese GOST 6008-90, gallium GOST 13637-93 in the amount of 10, 1.00, 0.25, respectively, and copper GOST 15471-77 the rest - 88.75 wt.%.

Before mixing, the starting components undergo appropriate processing:

- Manganese, germanium and gallium are degreased and wiped with alcohol,

- Copper is degreased, poisoned and annealed in a hydrogen medium.

In this case, gallium is used as a ligature in copper.

Further, these weighed portions of the components of manganese, germanium and gallium in copper are mixed and melted at a given temperature in high vacuum.

Next, the obtained solder blank is cleaned, annealed in high vacuum, and rolled to obtain a foil of a given thickness.

Examples 2-5.

Solders are made analogously to example 1, but with other ratios of the starting components indicated in the claims, as well as beyond.

The manufactured solders were used for soldering oxide dielectric materials with MOB grade copper:

a) alumina ceramics grade VK94-1,

b) beryllium ceramics grade OB-1.

Soldering is carried out in high vacuum, the pressure is not worse than 1.33 × 10 ^-3 Pa.

On the fabricated samples of soldered joints were measured:

Mechanical strength for static bending according to the four-point pattern on a tensile testing machine type RM-500.

Tightness with the help of a helium leak detector type PTI-10 with a leakage rate of no worse than 1.3 × 10 ^-11 m ³ Pa / s.

In addition, heat resistance was determined as a result of the following test cycle, namely:

fifty heatings in the soldering mode up to 900-950 ° С, three times heating in hydrogen up to 950 ° С, warming up at 650 ° С for 12 hours, ten thermal cycles at a temperature from -60 to 150 ° С in air.

Moreover, after each type of test, the tightness and integrity of the soldered joint are checked. The table gives the final result.

The test results are summarized in table.

As can be seen from the table

The mechanical resistance to static bending of samples of brazed joints made using a solder of a quantitative composition having a ratio of the starting components claimed in the claims is approximately 260 MPa, which indicates an increase in mechanical strength compared to the prototype (example 11) by 40-60 MPa ; tightness is maintained no worse than 1.3 × 10 ^-11 m ³ Pa / s; heat resistance after the above test cycle is also preserved (examples 1-3 and 6-8),

in contrast to samples of brazed joints made using solder of a quantitative composition having a ratio of the starting components outside the limits stated in the claims (example 4-5 and 9-10), where the mechanical strength is less than 200 MPa; leakage occurs; not all samples underwent thermal cycling.

It should be noted that the test results of the soldered joints of these dielectric materials are somewhat different from each other due to the fact that beryllium oxide is characterized by lower chemical activity.

Thus, the proposed solder for soldering in comparison with the prototype will allow:

firstly, to increase the reliability of the solder joint by increasing the mechanical strength by about 20 percent while maintaining the level of tightness and heat resistance,

secondly, expand the functionality.

It should be noted that the proposed solder, which provides a sufficiently high level of the above technical characteristics, can be especially in demand when soldering elements of microwave electronic products.

Information sources

1. RF patent No. 2041783, IPC V23K 35/30, filing date 1993.04.08, publ. 1995.08.20.

2. Gladkov A.S., Podvigina O.P., Chernov O.V. Soldering parts of vacuum equipment. M .: Energy, 1967, p. 212-217.

3. Copyright certificate No. 449791, IPC V23K 35/30, application No. 1894175 priority 26.02.73, publ. in bull. No 42 on 11/15/74.

Table №№ The composition of the solder, wt.% Test results Germanium Manganese Gallium Copper Maximum bending strength, MPa Tightness, leakage rate no worse, m ³ Pa / s Heat resistance and integrity (final result) one. Alumina Ceramics with Copper 10 one 0.25 88.75 260 1.3 × 10 ^-11 Heat resistance and integrity preserved 2. 7 0.08 0.05 92.87 255 1.3 × 10 ^-11 Heat resistance and integrity preserved 3. 12.5 1,2 0.5 85.8 240 1.3 × 10 ^-11 Heat resistance and integrity preserved four. 6 0,07 0.04 93.89 180 1.0 × 10 ^-8 Heat resistance is broken 5. 13 1.35 0.6 85.05 170 1.0 × 10 ^-8 Heat resistance is broken 6. Beryllium ceramics with copper 10 one 0.25 88.75 180 1.3 × 10 ^-11 Heat resistance and integrity preserved 8. 7 0.08 0.05 92.87 175 1.3 × 10 ^-11 Heat resistance and integrity preserved 12.5 1,2 0.5 85.8 176 1.3 × 10 ^-11 Heat resistance and integrity preserved 9. 6 0,07 0.04 93.89 140 1.0 × 10 ^-8 Heat resistance is broken 10. 13 1.35 0.6 85.05 128 1.0 × 10 ^-8 Heat resistance is broken 11 - prototype 18.5 0.8 absent 80.7 200 1.3 × 10 ^-11 Heat resistance and integrity preserved

Claims (2)

1. Solder based on copper for soldering elements of electronic products containing germanium and manganese, characterized in that it additionally contains gallium and obtained by melting the starting components in the following ratio, wt.%:
Germanium 7-12.5 Manganese 0.08-1.2 Gallium 0.05-0.5 Copper Rest 2. The solder according to claim 1, characterized in that it is designed for soldering elements of electronic products from oxide dielectric materials between each other, or with elements from metals, in particular from copper, or from their alloys.