SK8133Y1 - Soft lead-free active solder and method of soldering - Google Patents

Abstract

Soft active solder for soldering non-metallic materials with non-metallic/metallic materials comprises indium and an active metal, which can be titanium or lanthanum. The proportion of indium is 54,0 % to 99,0 % by weight, the proportion of titanium is 1,0 % to 4,0 % by weight, the proportion of lanthanum is 1,0 to 2,0 % by weight. The proportion of silver Ag can be 1,0 % to 15,0 % by weight and the proportion of tin can be 1,0 % to 30,0 % by weight. Non-metallic materials are soldered with non metallic/metallic materials by contact heating and at the same time by ultrasound directly without preliminary coating of the soldered surfaces. It can be soldered by solder in the second phase of consecutive soldering wherein in the first phase it is soldered with different solder having higher soldering temperature.

Description

S K8133 Y

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, T1O2, etc.), some non-metallic (Si, Ge, graphite, etc.) and difficult-to-solder metal materials (W, Mo, Ta, etc.) are soldered indirectly by surface of the ceramic material, a solderable metal coating is applied 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 solderable metal coating with and then obtains:

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 by the solder, which is otherwise non-wettable.

It is known in the art to solder non-metallic materials (Al2O3, S1O2, T1O2, etc.) or difficult-to-solder materials (W, Mo, Ta, etc.), so-called brazing materials. 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 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 materials with different thermal expansion, residual stresses occur.

Indium is used as an additive in several solders, such as disclosed in CN103909363, EA201200633, EP2756914, US5341981, RU2006146450, where it typically does not exceed 15% by weight.

A new solder composition is desirable to shorten the brazing time of brittle non-metallic materials such as silicon, germanium, sapphire, glass, glass ceramics and to allow the solder to compensate for residual stresses due to different thermal expansion of materials, for example when soldering ceramics with metal. allowing ultrasonic soldering at temperatures of about 200 ° C.

The essence of the technical solution

The disadvantages 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 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), soft and 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. If the lanthanum active metal is used, its proportion will be 1.0% to 2.0% by weight. In addition, the solder may include silver in the range of 1.0% to 15% 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.

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, soldered joints are able to compensate for their residual stresses due to different thermal expansion com2 by their plastic deformation (slip or creep mechanism).

With K8133 Y the differentiation of various materials, for example ceramic / metal materials. In this way, the most significant reduction of 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 brittle (glass, S1O2 ceramics, sapphire, carbon, silicon, germanium) can be soldered by soft active solders according to this invention. but also almost all types of ceramics). The solder according to this invention is therefore suitable for joining brittle materials and composite materials with a very different coefficient of thermal expansion.

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

Indium soldering has proven to be advantageous, 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 A1N, for joining targets for PVD sputtering and the like. The soft solder according to this invention 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. 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 step of successive soldering, wherein in the first step it is soldered by a different solder with a higher soldering temperature.

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 to solder 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 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 brazing joint for various brazed material pairs.

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

Active solder InSn30Ag4Ti3 in foil form was used to solder the SiO2 ceramic with copper. 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 active indium-based solder with a composition was used

InAg10Ti3 in the form of an ingot. The brazing was carried out by heating with a hot plate with the support of 40 kHz ultrasonic activation. The brazing temperature was 240 ° C.

S K8133 Y

Example 5

In this example according to Figure 1, various pairs of materials were soldered with InlOAg4Ti solder, namely Ni / Ni, ZrCh / Cu, Al / Cu, Cu / Cu, Al / Al, Al2O3 / CU, Ag / Ag and SS / SS ( SS - stainless 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 (8)

PROTECTION REQUIREMENTS 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. Method according to claim 6, characterized in that the non-metallic materials and the non-metallic / metal materials are laser-soldered simultaneously. Method 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, wherein the first step is soldered by a different higher temperature solder. soldering.