RU2614844C1 - Easily fusible glass composition production method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: easily fusible glass composition is obtained by mixing easily fusible glass, containing PbO, As₂O₃, ZnO_, Al₂O_3, SiO₂, crystalline lead titanate PbTiO₃ and zircon ZrSiO₄. The specific surface area of zircon is 1200-1400 cm²/g, the easily fusible glass - 2500-2700 cm²/g. Lead titanate is introduced into bidispersed condition - in the form of powder with a value of specific surface area 1100-1300 cm²/g and up to 6 wt % above 100% as a fraction with a particles size less than 3 microns. The composition content is the following, mass %: lead titanate - 20-50; zircon - 0.1-5; easily fusible glass - the rest up to 100, lead titanate with a particle size of not more than 3 microns - up to wt % 6 above 100.

EFFECT: mechanical strength of obtained soldered products increase and improving the glass compositions obtaining technology.

2 ex, 4 tbl

Description

The invention relates to the field of low-melting glass-crystal composite materials intended for vacuum-tight low-temperature brazing of corundum ceramics, in particular integrated circuit cases.

A known method of manufacturing a composition for fusible solder material, which consists in mixing 79.4-88.5 mass. % glass, ground to a fineness of 2000 cm ² / g, and 11.5-20.6 mass. % fine powder of crystalline cordierite filler (2MgO - 2Al ₂ O ₃ - 5SiO ₂ ), crushed to a specific surface area of 3000 cm ² / g, in a planetary mill for 3-5 min [1]. Glass has a composition, mass. %: B ₂ O ₃ - (10-13), SiO ₂ - (0.1-0.9), Al ₂ O ₃ - (0.1-0.8), PbO - (70-75), PbF ₂ (5-10), ZnO - (0.1-1.3), TeO ₂ - (3.5-9.0). A binder solution is added to the resulting composition until a paste is obtained, which is applied to the soldered products. Sealing the cases is carried out by heating the assembly of soldered parts to 385-395 ° C and holding at this temperature for ≈20 min [1]. The disadvantages of this method are the low values of the bending junction strength (up to 20 MPa) and the presence of toxic and expensive tellurium dioxide in the glass.

There is also a known method of obtaining a composition for fusible glass crystal material, which consists in mixing in an agate drum of a ball mill 44-83 masses. % fusible glass, crushed in the same mill to obtain a powder with a specific surface area of 2000 cm ² / g, and 17-56 mass. % powder of lead titanate (PbTiO ₃ ) with a specific surface area of 2000 cm ² / g [2]. Fusible glass has the following composition, mass. %: PbO - (72-92), В ₂ O ₃ - (6-20), Bi ₂ O ₃ - (0,1-18), PbF ₂ - (0,1-15), ZnO - (0, 1-10), SiO ₂ - (0.1-3), Al ₂ O ₃ - (0.1-3), MnO - (0.1-2.0), CoO - (0.1-2, 0), V ₂ O ₅ - (0.1-1.5). On the basis of the glass crystal composition and the organic binder, a paste is prepared which is applied to the soldering area. The specified method of obtaining the composition does not provide high strength junction of ceramics due to inconsistency of the values of the thermal expansion coefficient of the glass composition and ceramic substrates.

A known method of obtaining a low-melting glass crystal material, which consists in mixing 20-55 vol. % crystalline filler (lead titanate, cordierite, zircon, willemite) having an average particle diameter of 4 μm and a glass powder of the same dispersion, which includes the following components, mass. %: PbO - (45-85), B ₂ O ₃ - (1-11), Bi ₂ O ₃ - (1-45), ZnO - (0-15), the sum of Al ₂ O ₃ and SiO ₂ - ( 0-5), CuO - (0-5) and V ₂ O ₅ - (0-5) [3]. In addition to these oxides, the glass contains F ₂ in an amount of 0-6 mass. % The LTEC of such a glass-crystalline material can vary within wide limits - (49-138) * 10 ^-7 K ^-1 . The soldering temperature of the specified composition 400 ° C and below. The patent [3] provides mechanical bending strength (up to 680 kg / cm ² ) of sintered specimens of the composition, rather than junction, which is not equivalent. The disadvantages of this material are low values of spreadability (up to 110%) at the soldering temperatures of corundum ceramics.

A known method of obtaining a composition, which consists in the joint grinding of glass granulate and crystalline filler powder in a ball mill to transform the starting components into a finely divided, well-mixed powder with a particle size of less than 5 microns [4]. Glass has a composition, mass. %: РbO - (30-55), V ₂ O ₅ - (30-55), Bi ₂ O ₃ - (0,1-18), ZnO - (2-7), Р ₂ O ₅ - (0, 1-10), Nb ₂ O _s - (0.1-10), Ta ₂ O ₅ - (0.1-10), ZnO - (0.1-10), BaO - (0.1-10) , SrO - (0.1-10), but under the condition that Bi ₂ O ₃ + P ₂ O ₅ + Nb ₂ O ₅ + Ta ₂ O ₅ + ZnO + BaO + SrO - (0.3-20), PbO can be replaced by Cs ₂ O in an amount of up to 25 mass. % The mixture may include up to 50 mass. % crystalline filler obtained from metal oxides of group V (P, As, Sb, V, Nb, Ta) and up to 90 wt. % silver or gold powder. The finished composition can be applied to the soldered product in the form of a dry powder or in the form of a paste with the addition of an organic binder with an evaporation temperature of 150-220 ° C. Depending on the combination of the TEC components, the composition can vary in the range (48-145) * 10 ^-7 K ^-1 , and the soldering temperature is over 300 ° C. [4] The disadvantage of the materials obtained is a complex, multicomponent composition, including toxic components, as well as low values of the strength characteristics of junctions (bending strength up to 15 MPa, peeling - up to 17 MPa).

By technical nature and the achieved result closest to the proposed method for the manufacture of low-melting glass solders is a method of manufacturing compositions based on low-melting glass, including, mass. %: PbO - (60-86); B ₂ O ₃ - (5-14); SiO ₂ - (0.9-3); Al ₂ O ₃ - (0.6-2); Bi ₂ O ₃ - (0.1-18); ZnO - (0.1-4); TiO ₂ - (0.1-2); CdO - (0.1-3); MnO ₂ - (0.1-4) [5]. The mixture for the composition contains 53.9-88 mass. % glass of the specified composition, 5-46 mass. % crystalline lead titanate (PbTiO ₃ ) and 0.1-10 β-eucryptite (Li ₂ O-Al ₂ O ₃ -2SiO ₂ ). The starting components are in a powder state and have specific surface values of 1800-2000 cm ² / g. The TECL of this glass composition is in the range (65-67) * 10 ^-7 K ^-1 and the sealing temperature (420-460) ° C. The material is used for sealing ceramic cup-type cases [5].

The disadvantages of the prototype are not sufficiently high strength characteristics of the products (bending strength up to 23 MPa, peeling - up to 29 MPa) and low spreadability (up to 110%) of the composition.

The technical result of the invention is to increase the mechanical strength of the resulting brazed products and increase the manufacturability of glass compositions.

This technical result is achieved by a method for producing a low-melting glass composition consisting of low-melting glass containing PbO, B ₂ O ₃ , ZnO, Al ₂ O ₃ , SiO ₂ , crystalline lead titanate PbTiO ₃ , including grinding the components and mixing them, while adding zircon ZrSiO ₄ with a specific surface value of 1200-1400 cm ² / g, lead titanate is introduced in a bidispersed state, namely in the form of a powder with a specific surface value of 1100-1300 cm ² / g, up to 6 mass. % in excess of 100% in the form of a fraction with a particle size of less than 3 μm, which corresponds to a specific surface area of 2900-3100 cm ² / g, fusible glass is crushed to a specific surface area of 2500-2700 cm ² / g in the following ratio of components in mass. %:

Lead Titanate - 20-50

Zircon - 0.1-5

Fusible glass - the rest is up to 100 mass. %

Lead titanate with a particle size of not more than 3 microns - up to 6 mass. % over 100%

The introduction of lead titanate into the composition in the form of a powder with a specific surface area of 1100–1300 cm ² / g in the form of a powder with a particle size of less than 3 μm leads to an increase in the strength of junctions, which may be associated with an increase in the active surface and relaxation of residual internal stresses. The introduction of the entire volume of the filler in the form of a powder with a particle size of less than 3 μm is unacceptable, since the thermal expansion coefficient of the obtained compositions will not correspond to the thermal expansion coefficient of the soldered corundum products, which will lead to the formation of stresses at the corundum - glass composition interface and, as a result, to a sharp decrease in the joint strength .

The achievement of the claimed technical result is confirmed by the following examples.

Example 1

For the manufacture of fusible compositions using glass composition, mass. %: PbO - 83.0, B ₂ O ₃ - 13.5, ZnO - 1.5, Al ₂ O ₃ - 0.9, SiO ₂ - 1.1, crushed in a planetary mill with zirconium balls to a specific surface value 2500 cm ² / g in an amount of 52.8 mass. % To the crushed low-melting glass add 3 mass. % crystalline zircon having a specific surface area of 1320 cm ² / g. Lead titanate, having a specific surface value of 1220 cm ² / g, is introduced into the mixture in an amount of 44.2 mass. %, a fraction less than 3 microns in size is taken in an amount of 0, 2, 4, 6 mass. % over 100%. Such a ratio of the starting components ensures the TECL of the glass composition close to that of the corundum substrates. The components are thoroughly mixed in a ball mill in an agate drum. An organic binder is added to the glass composite to form a paste. Samples for measuring the mechanical strength of the junction are prepared by soldering through a layer of glass-crystal composite material of two corundum plates 25 mm long, 7 mm wide and 2 mm thick (the total length of the welded samples was 45 mm). The plates were brazed in an electric furnace at a heating rate of 5 ° C / min with holding at a temperature of 430 ° C for 30 minutes. In the table. 1 shows the compositions of low-melting glass crystal compositions.

Determining the strength of the obtained junctions was carried out by the method of 3-point bending. The measurements were carried out on 10 samples for each composition. The average values of strength characteristics are presented in table 2.

The selected combinations of raw materials (low-melting glass, lead titanate and zircon) provide products with a tensile strength of up to 37 MPa, which is 27% higher than the strength of the prototype, bending - up to 31 MPa, which is 35% higher than the similar characteristics of the prototype, which demonstrate table 2 data.

Example 2

Samples were made in accordance with example 1. Fusible glass composition, mass. %: PbO - 80.0, B ₂ O ₃ - 12.0, ZnO - 3.0, Al ₂ O ₃ - 2.0, SiO ₂ - 3.0, crushed to a specific surface area of 2700 cm ² / g, took in the amount of 60, 70 and 79.9 mass. %, mixed with 35, 28 and 20 mass. % lead titanate having a specific surface value of 1100 cm ² / g, and 5, 2 and 0.1 mass. % zircon with a specific surface area of 1200 cm ² / g Lead titanate having a particle size of less than 3 μm was added in an amount of 6 mass. % over 100%. Table 3 shows the compositions of low-melting glass crystal compositions.

The determination of the strength characteristics of the obtained junctions was carried out similarly to the method described in example 1, their average values are presented in table 4.

The presence of a fine fraction of crystalline lead titanate in the mixture increases the uniformity and strength of the composition by achieving a denser structure during sintering, which is due to the creation of a larger number of single contacts.

The selected values of specific surfaces and mass ratios of lead and zircon titanate provide the TECL of glass compositions in the range (66 ± 3) * 10 ^-7 , K ^-1 , which corresponds to the TEC of corundum substrates. When using more coarse powders, the required TEC value can be achieved with less filler, but the properties of such a composition are heterogeneous in volume and have low strength characteristics. The use of finely dispersed powder of lead titanate will lead to the fact that in order to achieve the desired value of TECL it will be necessary to use a larger amount of filler, which will negatively affect the flowability of the resulting compositions. Zircon, having an TEC value intermediate between lead titanate and low-melting glass, is introduced into the composition of the solder as a buffer.

Thus, the claimed method has the following advantages:

- provides obtaining fusible glass compositions having enhanced strength characteristics;

- uses a simple small-component technological composition of low-melting glass;

- combines high strength values and acceptable values for spreadability with solderability with stable and reproducible results.

Used Books:

1. Patent RU No. 2053211, IPC С04В 37/00 dated 01/27/1996

2. Patent RU No. 2197441, IPC С03С 8/24 of 01/27/2003

3. US patent No. 5346863 A, IPC C03C 3/142 from 09/13/1994

4. GB patent No. 0405622 A2, IPC С03С 8/24 dated 02.01.1991

5. Patent RU No. 958354, IPC С03С 3/10 dated 09/15/1982

Claims (5)

A method for producing a low-melting glass composition consisting of low-melting glass containing PbO, B ₂ O ₃ , ZnO, Al ₂ O ₃ , SiO ₂ , crystalline lead titanate PbTiO ₃ , comprising grinding the components and mixing them, characterized in that ZrSiO ₄ is additionally introduced with a specific surface value of 1200-1400 cm ² / g, lead titanate is introduced in a bidispersed state, namely in the form of a powder with a specific surface value of 1100-1300 cm ² / g, up to 6 wt.% in excess of 100% in the form of a fraction with particle size less than 3 microns, which corresponds to the value of the specific surface 2900- 3100 cm ² / g, fusible glass is crushed to a specific surface value of 2500-2700 cm ² / g in the following ratio of components in wt.%: Lead Titanate - 20-50 Zircon - 0.1-5 Fusible glass - the rest is up to 100 wt.% Lead titanate with a particle size of not more than 3 microns - up to 6 wt.% In excess of 100%.