SK500792017U1 - Soft lead-free active solder and method of soldering - Google Patents

Abstract

The soft active solder for soldering non-metallic materials with non-metallic / metallic materials consists of indium and the active metal, which may be titanium or lanthanum. Indium has a proportion of 54.0% to 99.0% by weight, titanium Ti has a proportion of 1.5% to 4.0% by weight, lanthanum has a proportion of 1.0% to 2.0% by weight. Silver Ag may have a proportion of 1.0% to 15.0% by weight. A tin may have a proportion of 1.0% to 30.0% by weight. Non-metallic materials with 10 nonmetallic / metallic materials are soldered by contact heating and ultrasound directly without prior coating of the brazed surfaces. The solder may be soldered in the second stage of the sequential soldering, whereby in the first stage a different solder with a higher soldering temperature is soldered.

Description

Technical field

The technical solution relates to a composition of a soft active solder based on indium for soldering non-metallic materials with non-metallic or metallic materials. The technical solution belongs to the field of soldering with lead-free solders, especially in the electrical industry.

BACKGROUND OF THE INVENTION

Ceramic materials (eg Al2O3, S1O2, TiO2, etc.) and some non-metallic (Si, Ge, graphite, etc.) and difficult-to-solder metal materials (W, Mo, Ta, etc.) are soldered indirectly by surface The solderable metal coating is applied to the ceramic material 15 before the soldering itself is realized. Surface plating eliminates the wettability problems of ceramic and some non-metallic materials. From the point of view of choice of plating type it is necessary to know at which operating temperature the soldered component will work. Accordingly, either soft or hard solder is used for soldering. The desired metal solder coating is then obtained:

Either by burning metal solutions of either refractory metals Mo, Mn, W (followed by nickel plating) or precious metals Ag, Au, Pt and the like; or by physical and chemical deposition to form thin coatings e.g. Au, Ag, Ni and combinations thereof.

The metal solder coating formed provides the necessary wettability of the surface of the material with a solder that is otherwise non-wettable.

It is known in the art to solder non-metallic materials 30 (Al2O3, SiO2, TiO2, etc.) or difficult-to-solder materials (W, Mo, Ta and the like) of so-called " direct soldering with the use of so-called. active solder, which contains a small amount of active metal (eg alkaline earth metals - Mg, Ba, etc.).

Most active solders are based on tin or lead. Lead is gradually being replaced by alternative elements as it is considered harmful.

EP 0349733 A1 discloses a silver-based solder 5 containing indium and titanium for direct soldering of ceramic materials. Such a solder has a high melting point of about 1000 ° C and the soldering must take place in a vacuum or argon shielding atmosphere. The solder according to this disclosure is intended for high-strength joints, especially in engineering applications. When soldering 10 materials with different thermal expansion, residual stresses occur.

Indium is used as an additive in a number of solders such as disclosed in CN103909363, EA201200633, EP2756914,

US5341981, RU2006146450, where it does not usually exceed 15% by weight of 15%.

A new solder composition is desired that shortens the brazing time of brittle non-metallic materials such as silicon, germanium, sapphire, glass, glass ceramics and allows the solder to compensate for residual stresses resulting from different thermal expansion of the materials, for example, 20 solder ceramics with metal. The solder should allow ultrasonic soldering at temperatures of about 200 ° C.

The essence of the technical solution

The drawbacks of the prior art are substantially eliminated by the soft lead-free active solder, which contains the active metal titanium or lanthanum according to the present invention, which is based on indium. Indium has a predominant proportion in the solder of this invention ranging from 54.0% to 99.0% by weight. When indium 30 is used in the prior art as an alloy with a small total proportion, often below 2.0 wt%, the soft solder of the present invention uses indium as the base of the solder. Indium is an easily fusible metal (melting point 156.60 ° C) is soft and well ductile. It is used as an alloy in alloys in the electrotechnical industry or also in engineering for sliding bearing plating.

The titanium active metal may have a fraction of 1.5% to 4.0% by weight.

In the case of using the active metal lanthanum, its proportion will be 1.0% to 2.0% by weight. and / or tin in the range of 1.0% to 30.0% by weight.

The solder may also contain conventional impurities and impurities such as bismuth, copper, aluminum, zinc, cerium, usually in trace amounts of 10.

This indium-based solder alloy, in combination with ultrasonic activation, is suitable for direct soldering of ceramic and other difficult-to-solder materials without coating and without the use of flux. When using indium-based soft solders, 15 solder joints are able to compensate by their plastic deformation (slip or flow mechanism) residual stresses from different thermal expansion combinations of different materials, for example ceramic / metal materials. In this way, the most significant reduction in residual stresses is achieved while maintaining the simplicity of the joint. The presence of the active element ensures good wettability of the soldered parts.

Unusual combinations of metallic materials (eg CrNi, steel, Mo, W, Ti, Cr, etc.) and non-metallic materials, mostly 25 brittle (glass, SiO 2, sapphire, carbon, silicon, but also almost all kinds of ceramics). The solder according to this invention is therefore suitable for joining brittle materials and composite materials with a very different thermal expansion coefficient.

Solder according to this technical solution is an excellent substitute for 30 lead solders for lower application temperatures, especially in electronics and electrotechnics, where lower strength and thermal resistance of the joint is sufficient.

Advantageously, soldering with indium-based solder has been found, for example, for soldering windows on lasers and spectroscopes, for making electrical connections to graphite, for soldering contacts to glass, for connecting heat exchangers to a ceramic electronic substrate of AI2O3 or AIN, for joining targets for PVD sputtering and the like. The soft solder according to this technical solution 5 also makes it possible to form vacuum-tight joints in vacuum and cryogenic techniques.

The indium-based solder of the present invention has a brazing temperature of about 200 ° C and has a shear strength of 13 to 71 MPa depending on the alloy content (silver or tin) that strengthens the solder matrix 10. The solder may take the form of a foil that is applied to the joint.

Alloying with titanium or lanthanum increases the wettability of the solder. Titanium but also lanthanum are generally very reactive metals. They have a high affinity for oxygen and other elements that are components of soldered materials.

Connected e.g. the ceramic material and the ceramic / metal material are soldered by contact heating and ultrasound or laser without coating, using this soft indium-based active solder with active metal. The solder can be soldered in the second stage of successive soldering, wherein in the first stage a different 20 solder with a higher soldering temperature is soldered.

The solder according to this technical solution is in combination e.g. with ultrasonic or laser or other activation (wave soldering or reflow soldering) suitable for direct soldering of ceramic and other difficult solderable materials without coating and without the use of flux. This reduces the time required to make the joints, improves the hygiene of the working environment, and improves the economy of production of the soldered joints. An essential advantage of the solder is its usefulness in non-uniform materials with different thermal expansion. The solder composition of this invention 30 provides acceptable solder tensile strength.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution is explained in more detail with the aid of Figure 1, where a graph is shown showing the shear strength of a brazed joint for different pairs of materials.

EXAMPLES

Example 1

The active solder has a composition of 98 wt. % indium and 2 wt. titanium.

Example 2

The active solder in this example has a composition of 99 wt. % indium and 1 wt. lanthanum.

Example 3

An active foil solder InSn30Ag4Ti3 was used for copper solder S1O2 ceramics. During soldering, the joint was heated by a hot plate with support for 40 kHz ultrasonic activation. The brazing temperature was 140 ^° C.

Example 4

In this example of a particular embodiment, an indium-based active solder with an ingot composition of 1nAg10Ti3 was used. Soldering was carried out by hot plate heating with the support of 40kHz ultrasonic activation. The brazing temperature was 240 ^° C.

Example 5

In this example of Figure 1, various pairs of materials were soldered with Ni10Ag4Ti solder, namely Ni / Ni, ZrC2 / Cu, Al / Cu, Cu / Cu, Al / Al, Al2O3 / Cu, Ag / Ag, and SS / SS (SS). steel, in this example AISI 316). The shear strengths achieved are shown in the graph in Figure 1.

Industrial usability

The industrial applicability of the technical solution is obvious. Indium based solders are a prospective substitute for lead solders.

The solder can be used in the electronics, electrotechnical industry.

Claims (5)

A soft lead-free active solder comprising active metal titanium Ti and / or lanthanum La, characterized in that it is based on indium In, wherein indium In has a proportion of 54.0% to 99.0% by weight. Soft lead-free active solder according to claim 1, characterized in that it comprises titanium Ti with a content of 1.5% to 4.0% by weight. Soft lead-free active solder according to claim 1 or 2, characterized in that it comprises lanthanum La with a proportion of 1.0% to 2.0% by weight. Soft lead-free active solder according to any one of claims 1 to 3, characterized in that it comprises silver Ag with a proportion of 1.0% to 15.0% by weight. Soft lead-free active solder according to any one of claims 1 to 4, characterized in that it comprises tin Sn with a proportion of 1.0% to 30.0% by weight. Indium In solder soft solder process according to any one of claims 1 to 5, characterized in that the non-metallic materials with the non-metallic / metal materials are soldered by contact heating and ultrasonic at the same time without prior coating of the soldered surfaces. A method according to claim 6, characterized in that the non-metallic materials with the non-metallic / metal materials are simultaneously soldered by laser. The method of soldering according to claim 6 or 7, characterized in that the non-metallic materials with the non-metallic / metal materials are soldered by successive soldering, wherein soldering is carried out in a second step of successive soldering. soldering temperature.