KR20200116430A - Lead free solder composition - Google Patents

Abstract

The present invention relates to a lead-free solder alloy composition having excellent solderability and mechanical properties. The lead-free solder alloy composition according to an embodiment of the present invention includes: an alloy solder containing Sn; and high entropy alloy nanopowder.

Description

Lead-free solder alloy composition {LEAD FREE SOLDER COMPOSITION}

The present invention relates to a lead-free solder alloy composition. More specifically, it is possible to minimize the influence of harmful metal elements on the environment by solving the environmental problem caused by the toxicity of lead (Pb), and relates to a lead-free solder alloy composition having excellent solderability and mechanical properties.

In general, Sn-Pb-based leaded solder has been used as a bonding material for electronic devices for a long time. In particular, it is used as a bonding material for mounting small electronic components such as semiconductor chips and resistance chips on printed circuit boards. come.

However, when disposing of electronic devices using leaded solder, the lead (Pb) component contained in the solder is eluted by acid rain and contaminates the groundwater. It is pointed out as material. Among them, lead (Pb) contained in leaded solder is strictly limited, and Sn-Pb solder is being replaced by lead-free solder.

For this reason, in recent years, various attempts have been made to develop environmentally friendly lead-free solder compositions by restricting or excluding the use of lead in the manufacture of solder alloys.

On the other hand, in recent years, in the research and development of lead-free solders containing elements such as Sn, Ag, Bi, Cu, In, and Zn, in particular, interest in compositions containing Sn, Ag, and Cu is increasing.

However, each of the aforementioned lead-free solders has disadvantages. Zn, for example, is sensitive to oxidation and consequently reduced solderability. Sn-Cu solder is inexpensive but has poor wettability, and since it is easy to form Ag3Sn, which is a coarse needle-like intermetallic compound in a solder containing Ag, the solderability is deteriorated and the strength is reduced. In the case of the existing commercial Sn-3.0Ag-0.5Cu (SAC305) solder, the wettability and reliability are excellent among lead-free solders, but the melting point is as low as about 221℃.

In recent years, the use of solder in automotive power semiconductors is increasing. In the case of the existing Si power semiconductor module, the device operating temperature was about 150°C on average, and it could be manufactured using the existing SAC305 solder. However, in recent years, SiC-based power semiconductors have been developed. At this time, the operating temperature of the device is driven at an average of 200°C or higher, and the instantaneous operation is about 235°C or higher, so there is a limit to applying the existing solder. High-temperature solder candidates to replace this include Au-Sn, Sn-Zn, and Sn-Al. However, Au is expensive, and Zn has a disadvantage of lowering the fluidity of the solder. In addition, Cu has poor wettability and has defects such as voids, and Al has a strong oxidation property, which causes serious problems in wettability.

In order to solve this problem, there is Sn-Sb having excellent mechanical strength, creep characteristics, and good wettability. In addition, studies on Sn-Bi-based solders are in progress as low-temperature solders used for low-temperature components. However, when Sb and Bi are added, the tensile strength increases, but since brittleness occurs and the hardness is increased, it is usually added at 4 to 5% or less.

In order to solve these Sn-Sb, Sn-Bi, and Sn-Ag-based solder problems, it is necessary to include fine-grained materials in the solder composition. These materials include aluminum nitride (AlN), yttrium oxide (Y ₂ O ₃ ) and There are ceramic nano powders such as silicon carbide (SiC). These ceramic nano-powder materials have the advantage of reinforcing solder by miniaturizing particles and being stable at high temperatures. However, ceramic nano-powder materials are brittle, and there is a difference between the known Sn metal and the crystal lattice, so when the solder is loaded, the ceramic nano-powder material itself is destroyed or cracks occur at the interface between the ceramic nano-powder material and the Sn metal. There is a drawback of lowering it.

In addition, ceramic nano-powder has a disadvantage in that it does not have good wettability, so that the powder is aggregated or not well mixed with known Sn metal when preparing a ceramic nano-composite solder alloy.

In addition, the spherical nano-powder has a relatively weak mechanical bond between the Sn metal and the nano-powder compared to the non-spherical nano-powder.

The present invention provides a lead-free solder alloy composition having excellent solderability and mechanical properties.

The lead-free solder alloy composition according to an embodiment of the present invention includes an alloy solder containing Sn and a high entropy alloy nanopowder.

Based on 100 parts by weight of the alloy solder, 0.01 to 1 part by weight of the high entropy alloy nanopowder may be included.

High entropy alloy nanopowder is among B, C, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Hf, Ta and W It may contain 4 or more types.

High entropy alloy nanopowder contains Fe, Co, Cr, Ni and Cu, contains Cu, Ni, Co, Fe and Mn, contains Al, Co, Cu, Fe and Ni, or contains Co, Cr, Fe , Containing Mn, Ni and Zn, containing Ni, Co, Fe, Cr and Mo, containing Ni, Co, Fe, Cr and Mn, containing Cu, Ni, Co, Fe and Mn, or containing Fe , Co, Cr, Ni and W, Ta, Nb, V, Ti and Al, or W, Nb, Mo, Ta and V.

The high entropy alloy nanopowder may contain 5 to 35 at% of each element.

High entropy alloy nanopowder is B, C, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Pd, Ag, Sn, Nd, Gd, Tb, Dy, Lu, Hf, Ta, W and Au may further contain 0.01 to 5 at% of one or more.

The high entropy alloy nanopowder may have an average particle diameter of 10 to 500 nm.

In an embodiment of the present invention, the lead-free solder alloy composition may further include ceramic nano powder or metal powder.

Based on 100 parts by weight of the alloy solder, 0.01 to 1 part by weight of ceramic nano powder or metal powder may be included.

Ceramic nanopowder is B (boron), Ti (titanium), Al (aluminum), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Zr. (Zirconium), Nb (niobium), Mo (molybdenum), Y (yttrium), La (lanthanum), Sn (tin), Si (silicon), Ag (silver), Bi (bismuth), Cu (copper), Oxide, nitride, carbide or boride of at least one element selected from the group consisting of Au (gold), Sr (strontium), Mg (magnesium), Pd (palladium), Pt (platinum), and Zn (zinc). I can.

The metal powder may contain one to three types of Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Hf, Ta, and W. have.

The ceramic nanopowder may have a metal coating layer formed on its surface.

The high entropy alloy nanopowder, ceramic nanopowder, or metal powder may have a surface roughness of 10% to 40% of the average particle diameter.

According to the lead-free solder alloy composition according to an embodiment of the present invention, by adding a high-entropy alloy nanopowder, toughness and elongation are high, and an effect of excellent spreadability can be expected.

1 is an FE-SEM photograph of Example 3.
2 is an FE-SEM photograph of Comparative Example 1.
3 is an FE-SEM photograph of Example 8.
4 is an FE-SEM photograph of Comparative Example 2.
5 is an FE-SEM photograph of Example 12.
6 is an FE-SEM photograph of Comparative Example 3.
7 to 10 are graphs of measurement results of tensile strength and elongation measured in Experimental Example 2.
11 is a graph showing the results of measuring spreadability measured in Experimental Example 3.

Terms such as first, second and third are used to describe various parts, components, regions, layers, and/or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for referring only to specific embodiments and is not intended to limit the present invention. Singular forms as used herein also include plural forms unless the phrases clearly indicate the opposite. As used in the specification, the meaning of “comprising” specifies a specific characteristic, region, integer, step, action, element and/or component, and the presence of another characteristic, region, integer, step, action, element and/or component It does not exclude additions.

Although not defined differently, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms defined in a commonly used dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal meaning unless defined.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

Lead-free solder alloy composition

The lead-free solder alloy composition according to an embodiment of the present invention includes an alloy solder containing Sn and a high entropy alloy nanopowder.

The alloy solder containing Sn may be Sn-Bi-based, Sn-Sb-based, or Sn-Ag-based.

Specifically, the Sn-Bi-based alloy solder may include Bi: 20 to 70% by weight, the remainder of Sn, and inevitable impurities, based on 100% by weight of the entire Sn-Bi alloy solder.

Specifically, the Sn-Sb-based alloy solder may include Sb: 0.1 to 30% by weight, the remainder of Sn, and inevitable impurities, based on 100% by weight of the entire Sn-Sb alloy solder.

Specifically, the Sn-Ag-based alloy solder may include Ag: 0.1 to 30% by weight, the remainder of Sn, and inevitable impurities based on 100% by weight of the entire Sn-Ag alloy solder.

The Sn-Ag-based alloy solder may be a Sn-Ag-Cu-based alloy solder further including Cu. In the case of further comprising Cu, Ag: 0.1 to 30% by weight, Cu: 0.1 to 30% by weight, the remainder of Sn and inevitable impurities may be included.

High entropy alloys are multi-component alloys in which four or more elements are composed of equal molar ratios or the content of each element is in the range of 5 to 35 at%. Further, based on the size of entropy, high entropy alloys have high entropy ((SSS, Ideal> 1.61R), SS-solid solution; R gas constant] and prefers a single solid solution phase over the formation of intermetallic compounds. The crystal structure of a completely irregularly arranged high entropy solid solution includes face centered cubic (FCC), body centered cubic (BCC), or hexagonal close packed (HCP).

These high entropy alloys have high strength and toughness due to severe lattice distortion, high temperature strength and structural stability superior to superalloys such as Inconel, have low creep resistance and diffusion rate, good weldability, high strain hardening ability, and flow stress. It has the characteristics of high strain sensitivity.

In an embodiment of the present invention, by adding a high entropy alloy together with an alloy solder, the matrix structure of the solder and the intermetallic compound present in the solder are uniformly refined to improve the strength and ductility of the alloy. In addition, it is possible to prevent cracking of the solder and suppress the formation of cavities. Accordingly, it is possible to prevent damage to the soldering unit joined to the electronic device, and increase the reliability and life of the soldering unit.

The high entropy alloy nanopowder may be added in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the alloy solder.

If too little of the high entropy alloy nanopowder is added, it is difficult to expect the micronization effect of the aforementioned intermetallic compound. Conversely, if too much of the high entropy alloy nanopowder is added, a problem may occur in that the above-described role is not smoothly performed due to agglomeration. More specifically, the high entropy alloy nanopowder may be added in an amount of 0.03 to 0.5 parts by weight based on 100 parts by weight of the alloy solder. More specifically, the high entropy alloy nanopowder may be added in an amount of 0.1 to 0.2 parts by weight based on 100 parts by weight of the alloy solder.

As described above, the high entropy alloy nanopowder may contain four or more atoms. More specifically, it may contain 4 to 7 types of atoms. More specifically, it may contain 5 to 6 types of atoms.

The types of elements included in the high entropy alloy nanopowder include B, C, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, It can be selected from Hf, Ta and W.

For example, among the combinations of the aforementioned atoms, including Fe, Co, Cr, Ni and Cu, including Cu, Ni, Co, Fe and Mn, or including Al, Co, Cu, Fe and Ni, or Co, Contains Cr, Fe, Mn, Ni and Zn, contains Ni, Co, Fe, Cr and Mo, contains Ni, Co, Fe, Cr and Mn, contains Ta, Nb, V, Ti and Al Or, it may include W, Nb, Mo, Ta and V. The combination described above is more excellent in terms of strength and ductility.

In addition to the above elements, high entropy alloy nanopowder is a trace element, B, C, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu Zn, Ge, Y , Zr, Nb, Mo, Ru, Pd, Ag, Sn, Nd, Gd, Tb, Dy, Lu, Hf, Ta, W and Au may further contain 0.01 to 5 at% of one or more of. In this case, when the type of the additional element (auxiliary element) and the main element included in the aforementioned 5 to 35 at% overlap, it means that the main element type is excluded. More specifically, 0.01 to 3 at% of the element may be further included.

The high entropy alloy nanopowder may have an average particle diameter of 10 to 500 nm. If the particle diameter of the high entropy alloy nanopowder is too small, agglomeration occurs between the high entropy alloy nanopowders, and solderability may be deteriorated. If the average particle diameter is too large, the micronization effect of the matrix structure of the solder and the intermetallic compounds present in the solder may not be significant. More specifically, the high entropy alloy nanopowder may have an average particle diameter of 30 to 100 nm.

In an embodiment of the present invention, the lead-free solder alloy composition may further include ceramic nano powder or metal powder.

By further adding ceramic nano powders or metal powders together with high entropy alloy nano powders, the matrix structure of the solder and the micronization effect of the intermetallic compounds present in the solder can be further improved. The addition of the ceramic nano-powder may have a more excellent synergistic effect than the addition of the metal powder.

The ceramic nano-powder or metal powder may be added in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the alloy solder.

When too little ceramic nano-powder or metal powder is added, it is difficult to expect the micronization effect of the aforementioned intermetallic compound. Conversely, if too much is added, a problem in which it is difficult to expect the aforementioned role may occur due to aggregation. More specifically, the ceramic nano powder or metal powder may be added in an amount of 0.03 to 0.5 parts by weight based on 100 parts by weight of the alloy solder. More specifically, the ceramic nano powder or metal powder may be added in an amount of 0.1 to 0.2 parts by weight based on 100 parts by weight of the alloy solder.

The high entropy alloy nano-powder and ceramic nano-powder or metal powder may be added in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the alloy solder. More specifically, the high entropy alloy nanopowder, ceramic nanopowder or metal powder may be added in an amount of 0.03 to 0.5 parts by weight based on 100 parts by weight of the alloy solder.

Ceramic nanopowder is B (boron), Ti (titanium), Al (aluminum), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Zr. (Zirconium), Nb (niobium), Mo (molybdenum), Y (yttrium), La (lanthanum), Sn (tin), Si (silicon), Ag (silver), Bi (bismuth), Cu (copper), Oxide, nitride, carbide, or boride of one or more elements selected from the group consisting of Sr (strontium), Mg (magnesium), Pd (palladium), Pt (platinum), and Zn (zinc) may be included.

More specifically, oxides, nitrides, carbides, or borides of at least one element selected from the group consisting of Al, Y, La, Ti, Sr, and Si may be included.

The trace element metal powder included in the high entropy alloy is a metal powder containing one to three metals, and is distinguished from the high entropy alloy nano powder containing four or more metals.

The metal powder may contain one to three types of Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Hf, Ta, and W. have.

The ceramic nano powder or metal alloy powder may have an average particle diameter of 10 to 500 nm. When the particle diameter of the ceramic nano-powder or metal alloy powder is too small, agglomeration occurs between the powders, and solderability may be deteriorated. If the average particle diameter is too large, the micronization effect of the matrix structure of the solder and the intermetallic compounds present in the solder may not be significant. More specifically, the ceramic nano powder or metal alloy powder may have an average particle diameter of 30 to 100 nm.

The ceramic nanopowder may have a metal coating layer formed on its surface. When a coating layer is formed on the surface of the ceramic nano powder, solder is wetted onto the surface of the additive. Accordingly, the ceramic nanopowder is pulled into the solder by the surface tension of the solder, and the ceramic nanopowder may diffuse into the solder. Therefore, the spreadability and wettability of the lead-free solder alloy composition can be improved.

The coating layer may include at least one metal selected from the group consisting of In, Sn, Sb, Bi, Zn, Cu, Ag, Au, Ni, Pt, Pd, Fe, Co, Ti, Cr, and Mn.

Specifically, the coating layer surrounds the surface of the ceramic nanopowder and may have an average thickness of 20 to 500Å. If the average thickness of the coating layer is too thin, the effect of improving the wettability and preventing aggregation of the ceramic nanopowder may be insignificant. On the other hand, if it is too thick, excessive intermetallic compounds may be formed depending on the coating metal, and problems of process cost and process time may occur. Specifically, the average thickness may be 50 to 400Å. More specifically, it may be 100 to 300 Å.

The high entropy alloy nano powder, ceramic nano powder, or metal alloy powder may have an uneven structure in which convex portions and concave portions are irregularly repeated on the surface.

Due to the presence of an uneven structure in which the convex and concave portions formed on the surface of high entropy alloy nano powder, ceramic nano powder, or metal alloy powder are irregularly repeated, solder is concave or hollow on the surface of the additive depending on the anchor effect. Can be mixed in. As a result, the mechanical bonding force increases, so that the strength and ductility of the soldering portion may be improved. In addition, when the crack propagation in the solder meets the ceramic particles, the cracks mainly propagate along the surface of the ceramic particles. Compared to the spherical powder, ceramic powder with irregularities delays the crack progress according to the change of the crack propagation direction and the increase of the propagation distance of the crack. . Due to this, the breakdown of the solder is delayed, and the strength and ductility of the soldered portion may be improved. Specifically, the high entropy alloy nanopowder, ceramic nanopowder, or metal alloy powder may have a surface roughness of 10% to 40% of the average particle diameter.

The high entropy alloy nanopowder, ceramic nanopowder, or metal alloy powder may be formed in an amorphous form.

The lead-free solder alloy composition according to the present invention can be used as a solder material. Specifically, it may be used for soldering a solder paste, a solder ball, a solder bar, a solder wire, and the like of an electronic product using the same.

Modern electronic devices are getting smaller and smaller to meet the demands of high integration, low power or portability, size, and operating voltage. One serious issue here is the wettability and strength of the soldering parts of electronic devices. In order to improve this, there is an increasing demand for a solder made of improved wettability and fine intermetallic compounds, and the lead-free solder alloy composition according to the present invention can be effectively used to improve this disadvantage.

Lead-free solder alloy composition manufacturing method

A method for preparing a lead-free solder alloy composition according to an embodiment of the present invention is not particularly limited.

As an example, the following method may be used.

Grinding and mixing the high entropy alloy raw material to prepare a high entropy alloy nanopowder, melting the alloy solder containing Sn, and adding the high entropy alloy nanopowder to the molten alloy solder, followed by stirring And preparing the composition.

When the ceramic nano powder is further included, the high entropy alloy nano powder and the ceramic nano powder are added to the molten alloy solder and then stirred to prepare a composition.

Instead of the molten solder, a high entropy alloy nanopowder may be added to the solder powder, or a high entropy alloy nanopowder and a ceramic nanopowder may be added and stirred to prepare a solder composition.

In an embodiment of the present invention, a method of manufacturing the high entropy alloy nanopowder is not particularly limited. For example, in the step of pulverizing and mixing a high entropy alloy raw material to prepare a high entropy alloy nanopowder, a high entropy alloy nanopowder may be prepared by ball milling the high entropy alloy raw material.

Ceramic nanopowder is manufactured by grinding ceramic raw materials. It is disposed in a vessel that can rotate horizontally and vertically, and a blade-shaped impeller can be used to crush the ceramic through the principle of revolution and rotation.

Specifically, ceramic nano-powder may be prepared such that amorphous ceramic nano-powder is included by using a vessel rotating at 10 to 50 rpm and an impeller rotating at 3000 to 14000 rpm in the vessel.

When the rotational speed of the impeller is faster than the rotational speed of the vessel, it is possible to prevent the phenomenon that ceramic nanopowder adheres to the inner wall of the vessel due to centrifugal force, making contact with the impeller difficult. Accordingly, the grinding efficiency can be increased.

As the rotational speed of the vessel and the impeller satisfies the above ranges, as energy efficiency is increased, tungsten can be efficiently pulverized, and amorphous ceramic nanopowder can be manufactured.

It may further include processing the surface of the ceramic nanopowder by performing at least one of plasma etching and sputtering. Through this, irregular shaped micro grooves are formed on the surface. This is to increase the bonding force with the metal material forming the coating layer.

Specifically, CF ₄ + O ₂ gas may be used. Plasma etching can be performed for 50 to 150 minutes under a vacuum degree of 25 to 40 mTorr. It can be sputtered for 80 to 200 seconds with a current of 20 to 40 mA under a vacuum degree of 0.01 to 1 mbar.

It may further include coating the surface of the ceramic nanopowder with a metallic material. This is a step to improve the wettability of the ceramic nano powder. When the non-metallic ceramic nanopowder is mixed with the alloy solder as it is, the ceramic nanopowder has poor wettability, and the ceramic powder is likely to be pushed upwards due to the buoyancy of the solder.

On the other hand, when the surface of the ceramic nanopowder is coated with a metal material, the additive may diffuse into the Sn-Bi alloy solder because the solder is wetted onto the surface of the additive and attracts the additive to the inside by the solder surface tension. . Due to this, mechanical bonding and mixing power between the ceramic nano powder and the alloy solder matrix may be improved.

Specifically, the surface of the ceramic nanopowder may be coated by a metal vapor deposition method such as a physical vapor deposition method (PVD) or a chemical vapor deposition method (CVD), or an electroless plating method.

In addition, a sputter coater may be used, and coating may be performed for 70 to 280 seconds with a current of 20 to 60 mA. By satisfying these conditions, an effect of depositing a coating layer of a uniform metal material on the surface of the ceramic nano powder can be expected.

After the ceramic nanopowder is manufactured, at least one of plasma etching and sputtering may be performed to process the surface of the ceramic nanopowder.

By performing one or more processes of plasma etching and sputtering on the surface of the ceramic nanopowder, an uneven structure in which convex portions and concave portions are irregularly repeated may be formed on the surface of the ceramic nanopowder on which the coating layer is formed. Due to the formation of such an uneven structure, Sn-Bi alloy solder may be mixed into concave portions or empty holes of the additive surface according to an anchor effect. As a result, the mechanical bonding force increases, so that the strength and ductility of the soldering portion may be improved.

Specifically, CF ₄ + O ₂ gas may be used. Plasma etching may be performed for 50 to 150 minutes under a vacuum degree of 25 to 40 mTorr. It can be sputtered for 80 to 200 seconds with a current of 20 to 40 mA under a vacuum degree of 0.01 to 1 mbar.

In the step of melting the alloy solder, the alloy solder may be melted by heating in an electric furnace. Specifically, it may be melted at a temperature of 200 to 800°C.

In the step of preparing the composition, a lead-free solder alloy composition may be prepared by mixing and stirring the high entropy alloy nano powder or the high entropy alloy nano powder and the ceramic powder and the molten alloy solder.

Specifically, it may be stirred for 10 to 50 minutes using a propeller rotating at 100 to 500 rpm. When the speed of the propeller is less than 100 rpm, the agitation becomes insufficient, and the nano-powder is easily entangled, so that the dispersion effect may not be large. If it exceeds 500rpm, solder may spatter. In addition, in the case of stirring in the air, oxidation of the solder may intensify. Therefore, the rotational speed of the propeller is controlled within the above range.

The propeller may be made of stainless steel, and in this case, the reactivity between the surface of the propeller and the solder is low, so that the stirring efficiency may be improved. In addition, a plate-shaped four-blade propeller having a thickness thinner than the diameter value of the shaft may be used. Accordingly, it is possible to prevent agglomeration of the additive, and expect the effect of uniformly dispersing the additive in the molten solder.

After the step of preparing the composition, it may further include processing the agitated composition into a solder ball by passing it through the through hole.

It is possible to manufacture in the form of a solder ball by passing the agitated and melted composition through a through hole having a certain size such as an orifice plate.

The method for preparing a lead-free solder alloy composition according to another embodiment of the present invention includes the steps of preparing a high entropy alloy nanopowder, preparing an alloy solder containing Sn in a powder form, and a high entropy alloy nanopowder and powder form. It includes the step of preparing a paste by mixing the alloy solder.

A description of the steps of preparing the high entropy alloy nanopowder or the high entropy alloy nanopowder and the ceramic powder is replaced by the description of the method for preparing the lead-free solder alloy composition.

Thereafter, an alloy solder containing Sn is prepared in the form of a powder, and mixed with the high entropy alloy nano powder or the high entropy alloy nano powder and ceramic powder prepared above, but mixed with a flux to prepare a solder paste form. .

Hereinafter, specific examples of the present invention will be described. However, the following examples are only specific examples of the present invention, and the present invention is not limited to the following examples.

Hereinafter, specific examples of the present invention will be described. However, the following examples are only specific examples of the present invention, and the present invention is not limited to the following examples.

Example: Preparation of Sn-Sb Solder Alloy Composition

Example 1

Fe-Co-Cr-Ni-Cu high entropy alloy containing 20at% of Fe, Co, Cr, Ni, and Cu by mixing and ball milling Fe powder, Co powder, Cr powder, Ni powder, and Cu powder respectively Nano powder was prepared. The average particle diameter of the high entropy alloy nanopowder was about 140 nm.

The vessel was rotated at 20 rpm, and the impeller was rotated at 4000 rpm to crush SiC for 20 minutes. Through this, amorphous SiC powder having a size of 100 nm or less was prepared.

Next, the surface of the SiC powder was plasma etched and sputtered. 95%CF ₄ + 5%O ₂ gas was used for plasma etching, and etching was performed for about 60 minutes at a vacuum degree of 25 mTorr. In addition, sputtering conditions were performed at room temperature for about 300 seconds, and sputtering was performed at a current of about 40 mA at a vacuum degree of 1 mbar.

Thereafter, the surface of the SiC powder was sputtered to coat the Au metal. The thickness of the coated metal was about 300 Å.

Next, the surface of the additive was plasma etched and sputtered. For plasma etching, 95%CF ₄ + 5%O ₂ gas was used, and etching was performed for about 40 minutes at a vacuum degree of 25 mTorr. In addition, sputtering conditions were performed at room temperature for about 300 seconds, and sputtering was performed at a current of about 40 mA at a vacuum degree of 1 mbar.

Sn-5.0wt%Sb solder was melted in an electric furnace at 350°C in an atmosphere and nitrogen atmosphere for about 20 minutes. Thereafter, 0.025 parts by weight of high entropy alloy nanopowder and 0.025 parts by weight of SiC powder were added to 100 parts by weight of solder, and stirred at 300 rpm for 30 minutes using a rectangular four-blade stainless steel propeller.

Example 2

In the same manner as in Example 1, 0.075 parts by weight of high entropy alloy nano powder and 0.075 parts by weight of SiC powder were added.

Example 3

In the same manner as in Example 1, 0.1 parts by weight of high entropy alloy nano powder and 0.1 parts by weight of SiC powder were added.

Example 4

In the same manner as in Example 1, 0.25 parts by weight of high entropy alloy nano powder and 0.25 parts by weight of SiC powder were added.

Example 5

Cu powder, Ni powder, Co powder, Fe powder, Mn powder are each mixed and ball milled,

Cu, Ni, Co, Fe, and Cu-Ni-Co-Fe-Mn high-entropy alloy nano-powder containing 20 at% each of Mn was prepared. The average particle diameter of the powder was about 130 nm.

Sn-5.0wt%Sb solder was melted in an electric furnace at 350°C in an atmosphere and nitrogen atmosphere for about 20 minutes. Thereafter, 0.1 parts by weight of high entropy alloy nanopowder and 0.1 parts by weight of Cu ₆ Sn ₅ powder were added with respect to 100 parts by weight of the solder, and stirred at 300 rpm for 30 minutes using a rectangular 4-blade stainless steel propeller.

Example 6

Al powder, Co powder, Cu powder, Fe powder, and Ni powder were each mixed and ball-milled, and Al: 7.5 at%, Co: 25 at%, Cu: 17.5 at%, Fe: 25 at%, and Ni: 25 Al-Co-Cu-Fe-Ni high entropy alloy nanopowder containing at% was prepared. The average particle diameter of the high entropy alloy nanopowder was about 150 nm.

Sn-5.0wt%Sb solder was melted in an electric furnace at 350°C in an atmosphere and nitrogen atmosphere for about 20 minutes. Thereafter, 0.1 parts by weight of high entropy alloy nanopowder and 0.1 part by weight of La ₂ O ₃ nanopowder were added to 100 parts by weight of the solder, and stirred at 300 rpm for 30 minutes using a stainless steel propeller in a rectangular 4-blade shape.

Example 7

Co powder, Cr powder, Fe powder, Mn powder, Ni powder, and Zn powder were each mixed and ball milled, Co: 20 at%, Cr: 20 at%, Fe: 20 t%, Mn: 5 at%, Co-Cr-Fe-Mn-Ni-Zr powder containing Ni: 20 at% and Zn: 15 at% was prepared. The average particle diameter of the high entropy alloy nanopowder was about 120 nm.

Sn-5.0wt%Sb solder was melted in an electric furnace at 350°C in an atmosphere and nitrogen atmosphere for about 20 minutes. Thereafter, 0.1 parts by weight of high entropy alloy nanopowder and 0.1 parts by weight of SrTiO ₂ powder were added to 100 parts by weight of the solder, and stirred at 300 rpm for 30 minutes using a rectangular 4-blade stainless steel propeller.

Comparative Example 1

Sn-5.0wt%Sb solder was used without the addition of high entropy alloy nano powder and ceramic powder.

Example: Preparation of Sn-Bi Solder Alloy Composition

Example 8

Ni powder, Co powder, Fe powder, Cr powder and Mo powder were each mixed and ball milled, and Ni: 20 at%, Co: 20 at%, Fe: 20 at%, Cr: 20 at%, and Mo: 20 Ni-Co-Fe-Cr-Mo powder containing at% was prepared. The average particle diameter of the high entropy alloy nanopowder was about 130 nm.

Sn-57wt%Bi solder was melted in an electric furnace at 280°C in an atmosphere and nitrogen atmosphere for about 20 minutes. Thereafter, 0.1 parts by weight of high entropy alloy nanopowder and 0.1 parts by weight of SiC powder were added with respect to 100 parts by weight of solder, and stirred at 300 rpm for 30 minutes using a rectangular 4-blade stainless steel propeller.

Example 9

Ni powder, Co powder, Fe powder, Cr powder and Mo powder were each mixed and ball milled, and Ni: 20 at%, Co: 20 at%, Fe: 20 at%, Cr: 20 at%, and Mo: 20 Ni-Co-Fe-Cr-Mo powder containing at% was prepared. The average particle diameter of the high entropy alloy nanopowder was about 120 nm.

Sn-57wt%Bi solder was melted in an electric furnace at 280°C in an atmosphere and nitrogen atmosphere for about 20 minutes. Thereafter, 0.375 parts by weight of high entropy alloy nanopowder and 0.375 parts by weight of SiC powder were added with respect to 100 parts by weight of solder, and stirred at 300 rpm for 30 minutes using a rectangular 4-blade stainless steel propeller.

Comparative Example 2

Sn-57wt%Bi solder was used without the addition of high entropy alloy nanopowder and additional powder.

Example: Preparation of Sn-Ag-Cu solder alloy composition

Example 10

Ni powder, Co powder, Fe powder, Cr powder and Mo powder were each mixed and ball milled, and Ni: 20 at%, Co: 20 at%, Fe: 20 at%, Cr: 20 at%, and Mo: 20 Ni-Co-Fe-Cr-Mo powder containing at% was prepared. The average particle diameter of the high entropy alloy nanopowder was about 130 nm.

Sn-3wt%Ag-0.5wt%Cu solder was melted for about 20 minutes in an electric furnace at 350°C in an atmosphere and nitrogen atmosphere. Thereafter, 0.1 parts by weight of high entropy alloy nanopowder and 0.1 part by weight of SiC nanopowder were added to 100 parts by weight of the solder, and stirred at 300 rpm for 30 minutes using a stainless steel propeller in a rectangular 4-blade shape.

Example 11

Cu powder, Ni powder, Co powder, Fe powder, and Mn powder are each mixed and ball-milled to provide Cu containing 20 at% Cu, 20 at% Ni, 20 at% Fe, 20 at% Fe and 20 at% Mn -Ni-Co-Fe-Mn powder was prepared. The average particle diameter of the high entropy alloy nanopowder was about 180 nm.

Sn-3wt% Ag-0.5wt% Cu solder was melted for about 20 minutes in an electric furnace at 350°C in an atmosphere and a nitrogen atmosphere. Thereafter, 0.2 parts by weight of high entropy alloy nanopowder was added to 100 parts by weight of the solder, and stirred at 300 rpm for 30 minutes using a stainless steel propeller in a rectangular 4-blade shape.

Comparative Example 3

Sn-3wt%Ag-0.5wt%Cu solder was used without the addition of high entropy alloy nanopowder and ceramic or metal powder.

Comparative Example 4

Without the addition of high entropy alloy nanopowder, 0.25 parts by weight of SiC powder was added to 100 parts by weight of Sn-3wt%Ag-0.5wt%Cu solder. It was stirred for 30 minutes at 300 rpm using a rectangular four-bladed stainless steel propeller.

Comparative Example 5

Without the addition of high entropy alloy nanopowder, 0.2 parts by weight of Ni nanopowder was added to 100 parts by weight of Sn-3wt%Ag-0.5wt%Cu solder. It was stirred for 30 minutes at 300 rpm using a rectangular four-bladed stainless steel propeller.

Experimental Example 1: Evaluation of microstructure characteristics

After solidification of the solder, a sample was taken, polished and etched, and then the microstructure was observed.

Comparing the crystal grains of Examples and Comparative Examples, the average grains of Example 3 were the finest, and Examples 8 and 10 had less refining effect compared to Example 1, but the refining effect was confirmed compared to Comparative Example.

FIG. 1 shows an FE-SEM photograph of Example 3, FIG. 2 is Comparative Example 1, FIG. 3 is Example 8, FIG. 4 is Comparative Example 2, FIG. 5 is Example 10, and FIG. 6 is a comparative example 3.

Alloy solder High entropy alloy nano powder (parts by weight) SiC (parts by weight) Intermetallic particles (㎛) Example 3 Sn-5wt%Sb 0.1 0.1 1.7 ± 0.8 μm Comparative Example 1 Sn-5wt%Sb - - 4.9 ± 2.3 μm Example 8 Sn-57wt%Bi 0.1 0.1 2.9 ± 1.4 μm Comparative Example 2 Sn-57wt%Bi - - 6.2 ± 3.3 μm Example 10 Sn-3wt%Ag-0.5wt%Cu 0.1 0.1 15.8 ± 4.7 μm Comparative Example 3 Sn-3wt%Ag-0.5wt%Cu - - 51.2 ± 2.8 μm

Experimental Example 2: Measurement of tensile strength and elongation

Tensile tests and elongation were measured for Examples and Comparative Examples.

Tensile strength was tested by ASTM: E8-M01 and KSB0801 method.

Elongation was tested by ASTM: E8-M01 and KSB0801 method.

Measurement results are shown in Tables 2 to 5 and FIGS. 7 to 10 below.

Alloy solder High Entropy Alloy Nano Powder High entropy alloy nano powder (parts by weight) SiC (parts by weight) Tensile strength (MPa) Elongation (%) Example 1 Sn-5wt%Sb FeCoCrNiCu 0.025 0.025 38.52 ± 0.09 18.38 ± 0.21 Example 2 Sn-5wt%Sb FeCoCrNiCu 0.075 0.075 38.73 ± 0.13 26.21 ± 0.26 Example 3 Sn-5wt%Sb FeCoCrNiCu 0.1 0.1 38.66 ± 0.16 27.28 ± 0.24 Example 4 Sn-5wt%Sb FeCoCrNiCu 0.25 0.25 38.96 ± 0.12 20.91 ± 0.21 Comparative Example 1 Sn-5wt%Sb - - - 39.60 ± 0.1 14.85 ± 0.19

Alloy solder High entropy alloy nano powder type (0.1 parts by weight) Additional powder (0.1 parts by weight) Tensile strength (MPa) Elongation (%) Example 3 Sn-5wt%Sb FeCoCrNiCu SiC 38.66 ± 0.16 27.28 ± 0.24 Example 5 Sn-5wt%Sb CuNiCoFeMn Cu ₆ Sn ₅ 36.2 ± 0.44 26.2 ± 0.26 Example 6 Sn-5wt%Sb AlCoCuFeNi La ₂ O ₃ 39.3 ± 0.63 27.65 ± 0.24 Example 7 Sn-5wt%Sb CoCrFeMnNiZn SrTiO ₂ 39.1 ± 0.31 24.38 ± 0.21 Comparative Example 1 Sn-5wt%Sb - - 39.60 ± 0.1 14.85 ± 0.19

Alloy solder High entropy alloy nano powder type High entropy alloy nano powder (parts by weight) SiC (parts by weight) Tensile strength (MPa) Elongation (%) Example 8 Sn-57wt%Bi NiCoFeCrMo 0.1 0.1 63.94 ± 0.31 34.45 ± 0.4 Example 9 Sn-57wt%Bi NiCoFeCrMo 0.375 0.375 66.81 ± 0.1 30.46 ± 0.3 Comparative Example 2 Sn-57wt%Bi - - - 65.44 ± 0.2 28.13 ± 0.3

Alloy solder High Entropy Alloy Nano Powder Additional powder Tensile strength (MPa) Elongation (%) Example 10 Sn-3wt%Ag-0.5wt%Cu NiCoFeCrMo (0.1 parts by weight) SiC (0.1 parts by weight) 57.99 ± 0.24 23.03 ± 0.18 Example 11 Sn-3wt%Ag-0.5wt%Cu CuNiCoFeMn (0.2 parts by weight) - 57.68 ± 0.11 21.33 ± 0.13 Comparative Example 3 Sn-3wt%Ag-0.5wt%Cu - - 59.88 ± 0.23 16.65 ± 0.09 Comparative Example 4 Sn-3wt%Ag-0.5wt%Cu - SiC (0.25 parts by weight) 59.54 ± 0.36 17.96 ± 0.21 Comparative Example 5 Sn-3wt%Ag-0.5wt%Cu - Ni (0.2 parts by weight) 58.72 ± 0.12 18.38 ± 0.12

Experimental Example 3: Measurement of spreadability

Spreadability was measured for Examples and Comparative Examples.

For the spreadability test, approximately 0.03 g of flux and about 0.3 g of the sample solder alloy are placed in the center of the copper sheet. Then, the copper sheet is placed in a molten solder bath maintained at 250°C. The sample solder soon started to melt, and after 30 seconds, the copper thin plate was taken out of the solder bath and cooled at room temperature to measure the spreading rate.

It measured using the JIS-Z-3197 standard measurement method.

The results are shown in Table 6 and FIG. 11 below.

Alloy solder High Entropy Alloy Nano Powder Additional powder Spreadability (%) Comparative Example 1 Sn-5wt%Sb - - 68.6 ± 0.11 Example 1 Sn-5wt%Sb FeCoCrNiCu (0.025 parts by weight) SiC (0.025 parts by weight) 68.9 ± 0.15 Example 2 Sn-5wt%Sb FeCoCrNiCu (0.075 parts by weight) SiC (0.075 parts by weight) 69.2 ± 0.16 Example 3 Sn-5wt%Sb FeCoCrNiCu (0.1 parts by weight) SiC (0.1 parts by weight) 69.4 ± 0.17 Example 4 Sn-5wt%Sb FeCoCrNiCu (0.25 parts by weight) SiC (0.25 parts by weight) 68.7 ± 0.16 Example 5 Sn-5wt%Sb CuNiCoFeMn (0.1 parts by weight) Cu ₆ Sn ₅ (0.1 parts by weight) 70.2 ± 0.17 Example 6 Sn-5wt%Sb AlCoCuFeNi (0.1 parts by weight) La ₂ O ₃ (0.1 parts by weight) 69.4 ± 0.14 Example 7 Sn-5wt%Sb CoCrFeMnNiZn (0.1 parts by weight) SrTiO ₂ (0.1 parts by weight) 69.9 ± 0.13 Comparative Example 2 Sn-57wt%Bi - - 72.1 ± 0.12 Example 8 Sn-57wt%Bi NiCoFeCrMo (0.1 parts by weight) SiC (0.1 parts by weight) 73.5 ± 0.15 Example 9 Sn-57wt%Bi NiCoFeCrMo (0.375 parts by weight) SiC (0.375 parts by weight) 72.9 ± 0.19 Comparative Example 3 Sn-3wt%Ag-0.5wt%Cu - - 74.7 ± 0.09 Comparative Example 4 Sn-3wt%Ag-0.5wt%Cu - SiC (0.2 parts by weight) 74.9 ± 0.15 Comparative Example 5 Sn-3wt%Ag-0.5wt%Cu Ni (0.2 parts by weight) 75.1 ± 0.13 Example 10 Sn-3wt%Ag-0.5wt%Cu NiCoFeCrMo (0.1 parts by weight) SiC (0.1 parts by weight) 75.1 ± 0.17 Example 11 Sn-3wt%Ag-0.5wt%Cu CuNiCoFeMn (0.2 parts by weight) - 75.3 ± 0.16

The present invention is not limited to the above embodiments and/or embodiments, but may be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains change the technical spirit or essential features of the present invention. It will be appreciated that it can be implemented in other specific forms without doing so. Therefore, it should be understood that the embodiments and/or embodiments described above are illustrative and non-limiting in all respects.

Claims (7)

Based on the total 100% by weight of the alloy solder, Sb: 0.1 to 30% by weight, the balance Sn and alloy solder containing inevitable impurities
Lead-free solder alloy composition containing high entropy alloy nano powder. Based on the total 100% by weight of the alloy solder, Ag: 0.1 to 30% by weight, the balance Sn and alloy solder containing inevitable impurities,
Lead-free solder alloy composition containing high entropy alloy nano powder. The method of claim 2,
The alloy solder is Ag: 0.1 to 30% by weight, Cu: 0.1 to 30% by weight, a lead-free solder alloy composition comprising the balance Sn and inevitable impurities. The method according to any one of claims 1 to 3,
Lead-free solder alloy composition comprising 0.01 to 1 part by weight of the high entropy alloy nano-powder based on 100 parts by weight of the alloy solder. The method according to any one of claims 1 to 3,
The high entropy alloy nanopowder is B, C, Mg, Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Hf, Ta and W Lead-free solder alloy composition comprising four or more of. The method according to any one of claims 1 to 3,
The high entropy alloy nanopowder contains Fe, Co, Cr, Ni and Cu, or contains Cu, Ni, Co, Fe and Mn, or contains Al, Co, Cu, Fe and Ni, Co, Cr, Contains Fe, Mn, Ni and Zn, contains Ni, Co, Fe, Cr and Mo, contains Ni, Co, Fe, Cr and Mn, contains Cu, Ni, Co, Fe and Mn, A lead-free solder alloy composition comprising Fe, Co, Cr, Ni and W, Ta, Nb, V, Ti and Al, or W, Nb, Mo, Ta and V. The method of claim 5,
The high-entropy alloy nano-powder is a lead-free solder alloy composition containing 5 to 35 at% each of the elements.

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