A low temperature lead-free active solder alloy and a method of making the same

Abstract

The application discloses a low-temperature lead-free active solder alloy, the solder alloy takes Sn-Sb-In-Ti as a base material, and the raw material components are as follows according to weight percentage: Sb 0.1-6%, In 4-52%, TiH2 1-23%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn, beneficial effects: the SiC / Cu-SiC combination is directly welded by using the Sn-Sb-In-Ti solder, the welding temperature is regulated by changing the content of Sb and In, so that the base material needing different welding temperatures can be adapted to; and the soldering effect is best by changing the content of Ti element and adding other elements.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding materials, technical field, in particular, to a low-temperature lead-free active solder alloy and a preparation method thereof. BACKGROUND

[0002] Solder suitable for AMB (Active Metal Brazing) substrates is widely used in the fields of electronic packaging, aerospace, energy, automotive industry, etc. In these fields, the function of the solder is to provide reliable connections, among which the main connected substrates are nS-SiO2, ITO, Al2O3, coated Al alloy, TiO2, graphite, AlN, SiN and SiC materials. One of the most important problems is the non-wetting of commercial solders on the above-mentioned materials. This problem can be solved by using active solders containing elements with high affinity for certain substrate components, so that it is not necessary to coat the substrate materials with a solderable coating. Titanium is the most commonly used element added to the solder, but other active metals are also used. By activating the soldering surface, titanium can make the solder wet and solder Ti, Al, Si, glass and different types of ceramic materials.

[0003] Sn-Ag-Ti is the most commonly used active solder base containing titanium addition, which was originally developed by S-Bond Technologies. This base can connect most metals, ceramics and composites without using flux or pre-coating the substrate, and does not contain lead or cadmium, meeting all requirements for lead-free soldering (RoHS, etc.). Chinese patent application No. CN113953612B reports a preparation method of active metal brazing copper-coated ceramic substrate, the material formula of which is silver powder 50%~80%, copper powder / silver-copper alloy powder 20%~40%, titanium hydride powder 1%~5%; Non-metallic components include binder, thixotropic agent, solvent. The processing technology of this method is to mix metal and compound powder with non-metallic solvent components to make solder paste. Patent No. CN114178738A reports a solder with similar processing technology, but the existing solders all need solvents or fluxes in addition to the main body metal materials of the soldering components, which increases the process complexity and reduces the soldering effect. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies of the prior art, the application provides a low-temperature lead-free active solder alloy and a preparation method thereof, and Sn-Sb-In-Ti solder is used to directly weld SiC / Cu-SiC combination, the welding temperature is adjusted by changing the content of Sb and In to adapt to the base material requiring different welding temperatures, the soldering effect is found by changing the content of Ti element and the addition of other elements, and the problems that the existing solder needs a solvent or fluxing agent in addition to the main body metal material of the soldering component, the process is complicated, and the soldering effect is reduced are solved.

[0006] (II) Technical scheme

[0007] To realize the above-mentioned advantages of finding the soldering effect of the solder by changing the content of the Ti element and the addition of other elements, the application adopts the following specific technical scheme:

[0008] A low-temperature lead-free active solder alloy, the solder alloy takes Sn-Sb-In-Ti as a base material, the content of Sb is less than 10%, the content of In is adjusted according to the required welding temperature of the solder, the content of Ti is less than 3%, one or more of Ag, Au, Zr, Cu, Hf, Ni, V and Nb is an active metal welding element to improve the wettability of the solder (the total content is less than 3%), one or more of trace elements Cu, Ni, Ag, Ge, P and Se is a solder brittleness-reducing element, the total amount is between 0.1 and 0.5 wt%, one or more of Ce, La, Pr, Y, Er, Tb, Eu, Nd and Yb is a rare earth element to improve the wettability, weldability, creep resistance, tensile strength and thermal fatigue reliability of the solder, the total amount is between 0.1 and 0.5 wt%, and the balance is Sn.

[0009] A preparation method of a low-temperature lead-free active solder alloy, comprising the following steps:

[0010] S1, Sn-xSb-yIn alloy powder, TiH2 powder and other active metal element powder, trace element powder and rare earth element powder with a proportion adjusted according to the required soldering temperature are processed by a ball mill, and the powder diameter is about 50 mu m.

[0011] S2, the mixed powder after ball milling is put into a mold, and is pressed by a hydraulic machine, the pressed sample is placed in a vacuum furnace, and is sintered at a vacuum degree of 10-5 Pa and a sintering temperature of 600 DEG C to obtain a solder,

[0012] S3, the sintered solder is further rolled and wire cut to obtain a preformed solder sheet.

[0013] The preform solder is performed under vacuum conditions of 1.3 to 2.0 x 10^-3 Pa. The preform solder is placed on the ceramic surface.

[0014] Subsequently, the sample is assembled into a sandwich structure. Then, the sample is heated to the soldering set temperature at a rate of 10 K / min (10 degrees Celsius per minute) and kept stable for 20 minutes.

[0015] Finally, the sample is cooled to room temperature at a rate of 20 K / min (20 degrees Celsius per minute).

[0016] (III) Beneficial Effects

[0017] Compared with the prior art, the present application provides a low-temperature lead-free active solder alloy and a preparation method thereof, which has the following beneficial effects: the present application adopts a direct and solvent-free solder processing technology to solve some problems existing in traditional soldering. By selecting a solder based on Sn-Sb-In-Ti as the soldering base material and optimizing and improving it, the solder has a wider soldering capacity by adding various active metal soldering elements, trace elements and rare earth elements, and can solder various ceramic, glass and other substrates. The composition of the Sn-Sb-In-Ti solder is carefully controlled. By changing the content of Sb and In, the soldering temperature can be controlled to meet the soldering needs of different substrates. Higher In content and lower Sb content can reduce the soldering temperature, which is suitable for substrates that require low-temperature soldering, while lower In content and higher Sb content are suitable for substrates that require higher soldering temperature. By adjusting the content of Ti, the optimal ratio of soldering elements can be found to achieve the best soldering effect on different substrates. The addition of Ti can activate the soldering surface and promote the wetting and bonding between the solder and the ceramic or glass substrate. In addition, the solder has a small coefficient of thermal expansion, which can reduce the thermal stress at the soldering interface, strengthen the soldering strength and improve the yield of the soldered joint. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 is a structural schematic diagram of the present application. DETAILED DESCRIPTION

[0020] To further illustrate the embodiments, the present application provides accompanying drawings, which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can be used to explain the operating principle of the embodiments in conjunction with the related description of the specification. Those skilled in the art should understand other possible implementations and advantages of the present application by referring to these contents. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0021] According to embodiments of the present application, a low-temperature lead-free active solder alloy and a method for preparing the same are provided.

[0022] Embodiment 1:

[0023] A low-melting-point lead-free AMB solder alloy, according to the percentage by weight, the raw material components are as follows: Sb 6%, In 4%, TiH2 1%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

[0024] Preparation steps:

[0025] According to the percentage by weight, Sb, In and Sn are added to a vacuum melting furnace, heated to 300°C at a heating rate of 20°C / min, kept for 1 h, stirred, and then heated to 550°C at a heating rate of 10°C / min, kept for 90 min, stirred, and cooled to room temperature at a cooling rate of 20°C / min. The obtained SnSbIn alloy is further mechanically crushed to prepare a powder. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder, and La powder are processed by a ball mill, and the powder diameter is about 50 μm. The mixed powder is placed in a mold and pressed by a hydraulic machine. The pressed sample is placed in a vacuum furnace for sintering under a vacuum degree of 10-5 Pa, and the sintering temperature is 600°C. The solder is obtained, and the sintered solder is rolled and wire cut to obtain a preformed solder sheet.

[0026] According to Figure 1 The preformed solder sheet is placed on the ceramic surface as shown in FIG. 1. Subsequently, the sample is assembled into a sandwich structure and welded under a vacuum condition of 1.3 to 2.0 x 10-3 Pa. Then, the sample is heated to the set welding temperature at a rate of 10 K / min (10 degrees Celsius / min) and kept stable for 20 min. Next, the sample is cooled to room temperature at a rate of 20 K / min (20 degrees Celsius / min).

[0027] The low melting point lead-free AMB solder alloy prepared in the experiment is tested for performance, with a solidus temperature of 226°C, a liquidus temperature of 251°C, a shear strength of 47 MPa, and a tensile strength of 43 MPa.

[0028] Example 2

[0029] A low melting point lead-free AMB solder alloy, according to weight percentage, the raw material components are as follows: Sb 6%, In 4%, TiH2 22%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

[0030] Preparation steps:

[0031] According to weight percentage, Sb, In and Sn are added to a vacuum melting furnace, heated to 300°C at a heating rate of 20°C / min, kept for 1 h, stirred, and then heated to 550°C at a heating rate of 10°C / min, kept for 90 min, stirred, and cooled to room temperature at a cooling rate of 20°C / min. The obtained SnSbIn alloy is further mechanically crushed to prepare a powder. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder, and La powder are processed by a ball mill, and the powder diameter is about 50 μm. The mixed powder is placed in a mold and pressed by a hydraulic machine. The pressed sample is placed in a vacuum furnace for sintering under a vacuum degree of 10-5 Pa, and the sintering temperature is 600°C. The solder is obtained, and the sintered solder is rolled and wire cut to obtain a preformed solder sheet.

[0032] According to Figure 1 The preformed solder sheet is placed on the ceramic surface. Then, the sample is assembled into a sandwich structure and welded under a vacuum condition of 1.3 to 2.0 x 10-3 Pa. Then, the sample is heated to the set welding temperature at a rate of 10 K / min (10 degrees Celsius / min) and kept stable for 20 min. Next, the sample is cooled to room temperature at a rate of 20 K / min (20 degrees Celsius / min).

[0033] The low melting point lead-free AMB solder alloy prepared in the experiment is tested for performance, with a solidus temperature of 220°C, a liquidus temperature of 243°C, a shear strength of 51 MPa, and a tensile strength of 46 MPa.

[0034] Example 3

[0035] A low melting point lead-free solder alloy, the raw material components are as follows according to percentage by weight: Sb 6%, In 4%, TiH2 3%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

[0036] Preparation steps:

[0037] Sb, In and Sn are added into a vacuum melting furnace according to percentage by weight, heated to 300℃ at a heating rate of 20℃ / min, kept for 1h, stirred, and then heated to 550℃ at a heating rate of 10℃ / min, kept for 90min, stirred, and cooled to room temperature at a heating rate of 20℃ / min. The obtained SnSbIn alloy is further mechanically pulverized to prepare a powder. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder and La powder are processed by a ball mill, and the diameter of the powder is about 50μm. The mixed powder is put into a mold and pressed by a hydraulic machine. The pressed sample is placed in a vacuum furnace for sintering under a vacuum degree of 10-5Pa at a sintering temperature of 600℃, and then the solder is obtained. The sintered solder is rolled and wire cut to obtain a preformed solder sheet.

[0038] According to Figure 1 The preformed solder sheet is placed on the ceramic surface as shown. Then, the sample is assembled into a sandwich structure and welded under a vacuum condition of 1.3 to 2.0x 10^-3Pa. Then, the sample is heated to the set welding temperature at a rate of 10K / min (10 degrees Celsius / min) and kept stable for 20min. Next, the sample is cooled to room temperature at a rate of 20K / min (20 degrees Celsius / min).

[0039] The low melting point lead-free AMB solder alloy prepared in the experiment is tested for performance, and the solidus temperature is 218℃, the liquidus temperature is 239℃, the shear strength is 56MPa, and the tensile strength is 51MPa.

[0040] Example 4:

[0041] A low melting point lead-free solder alloy, the raw material components are as follows according to percentage by weight: Sb 6%, In 4%, TiH2 3%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

[0042] Preparation steps:

[0043] Sb, In, Sn are added into a vacuum melting furnace according to the weight percentage, heated to 300℃ at a heating rate of 20℃ / min, kept for 1h, stirred, continue to heat to 550℃ at a heating rate of 10℃ / min, keep for 90 minutes, stir, cool to room temperature at a cooling rate of 20℃ / min, the obtained SnSbIn alloy is further mechanically crushed to prepare a powder. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder, La powder are processed by a ball mill, and the powder diameter is about 50μm. The mixed powder is put into a mold and pressed by a hydraulic machine, and the pressed sample is placed in a vacuum furnace for sintering under a vacuum degree of 10-5Pa, and the sintering temperature is 600℃, to obtain a solder, and the sintered solder is rolled and wire cut to obtain a preformed solder sheet

[0044] According to the preparation method of the low melting point lead-free solder alloy in the embodiment 1, the Sn, Sb, In, TiH2, Ag, Cu, Hf, Ni, Ge, Pr, Yb, La are added into a vacuum melting furnace according to the weight percentage, heated to 300℃ at a heating rate of 20℃ / min, kept for 1h, stirred, continue to heat to 550℃ at a heating rate of 10℃ / min, keep for 90 minutes, stir, cool to room temperature at a cooling rate of 20℃ / min, the obtained SnSbIn alloy is further mechanically crushed to prepare a powder. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder, La powder are processed by a ball mill, and the powder diameter is about 50μm. The mixed powder is put into a mold and pressed by a hydraulic machine, and the pressed sample is placed in a vacuum furnace for sintering under a vacuum degree of 10-5Pa, and the sintering temperature is 600℃, to obtain a solder, and the sintered solder is rolled and wire cut to obtain a preformed solder sheet Figure 1 The preformed solder sheet is placed on the ceramic surface as shown in FIG. 1. Subsequently, the sample is assembled into a sandwich structure and welded under a vacuum condition of 1.3 to 2.0 x 10-3Pa. Then, the sample is heated to the welding set temperature at a rate of 10K / min (10 degrees Celsius / min) and kept stable for 20 minutes. Next, the sample is cooled to room temperature at a rate of 20K / min (20 degrees Celsius / min).

[0045] The performance of the low melting point lead-free AMB solder alloy prepared in the experiment is tested, the solidus temperature is 210℃, the liquidus temperature is 233℃, the shear strength is 50MPa, and the tensile strength is 45MPa.

[0046] Embodiment 5:

[0047] A low melting point lead-free solder alloy, according to the weight percentage, the raw material components are as follows: Sb 0.1%, In 52%, TiH2 3%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

[0048] Preparation steps:

[0049] Sb, In, Sn are added into a vacuum melting furnace according to weight percentage, heated to 300 DEG C at a heating rate of 20 DEG C / min, kept for 1 h, stirred, continue to heat to 550 DEG C at a heating rate of 10 DEG C / min, keep for 90 min, stir, cool to room temperature at a heating rate of 20 DEG C / min, the obtained SnSbIn alloy is further prepared into powder by mechanical crushing method. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder, La powder are processed by a ball mill, and the diameter of the powder is about 50 mu m. The mixed powder is put into a mold, and is pressed by a hydraulic machine, the pressed sample is placed in a vacuum furnace, sintered under a vacuum degree of 10-5 Pa, the sintering temperature is 600 DEG C, the solder is obtained, and the sintered solder is rolled and cut by a wire to obtain a preformed solder sheet

[0050] According to the present application, the solder alloy is prepared by the following steps: Figure 1 The preformed solder sheet is placed on the ceramic surface as shown in the drawing. Then, the sample is assembled into a sandwich structure, and is welded under a vacuum condition of 1.3 to 2.0 x 10-3 Pa. Then, the sample is heated to the welding setting temperature at a rate of 10 K / min (10 DEG C / min), and is kept stable for 20 min. Next, the sample is cooled to room temperature at a rate of 20 K / min (20 DEG C / min).

[0051] The performance of the low-melting-point lead-free AMB solder alloy prepared in the experiment is tested, the solidus temperature is 118 DEG C, the liquidus temperature is 146 DEG C, the shear strength is 33 MPa, and the tensile strength is 20 MPa.

[0052] In the present application, unless otherwise clearly specified and limited, the terms such as "mounting", "setting", "connecting", "fixing", "screwing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise clearly limited, the above-mentioned terms in the present application can be understood according to the specific meaning of the above-mentioned terms in the present application by the person skilled in the art.

[0053] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low temperature lead-free active solder alloy, said solder alloy having a base material of Sn-Sb-In-Ti, characterized in that, in terms of weight percentage, The raw material components are as follows: Sb 0.1-6%, In 4-52%, TiH2 1-23%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

2. The low temperature no-lead active solder alloy according to claim 1, said solder alloy having a base material of Sn-Sb-In-Ti, in terms of weight percentage, characterized in that, The raw material components are as follows: Sb 6%, In 4%, TiH2 1%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

3. The low temperature no-lead active solder alloy according to claim 1, said solder alloy having a base material of Sn-Sb-In-Ti, in terms of weight percentage, characterized in that, The raw material components are as follows: Sb 6%, In 4%, TiH2 2%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

4. The low temperature no-lead active solder alloy as claimed in claim 1, wherein the solder alloy is based on Sn-Sb-In-Ti, and in terms of weight percentage, it comprises: Sn 63-68% Sb 0-3% In 0.5-2% Ti 0.1-0.5% The raw material components are as follows: Sb 2%, In 9%, TiH2 3%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn. ​ 5. The low temperature no-lead active solder alloy as claimed in claim 1, wherein the solder alloy is based on Sn-Sb-In-Ti, and in terms of weight percentage, it contains 0.5-2.0% of Sn, 0.5-2.0% of Sb, 0.5-2.0% of In, and 0.5-2.0% of Ti. The raw material components are as follows: Sb 0.1%, In 52%, TiH2 3%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

6. The low temperature no-lead active solder alloy as claimed in claim 1, wherein the solder alloy is based on Sn-Sb-In-Ti, and in terms of weight percentage, it contains 0.5-2.0% of Sn, 0.5-2.0% of Sb, 0.5-2.0% of In, and 0.5-2.0% of Ti. The raw material components are as follows: Sb 6%, In 4%, TiH2 3%, Ag 0.1%, Cu 3%, Hf 1%, Ni 2%, Ge 0.5%, Pr 0.5%, Yb 0.3%, La 0.3%, and the balance is Sn.

7. The method for preparing a low-temperature lead-free active solder alloy as described in claim 1, characterized in that, The method comprises the following steps: S1. According to the weight percentage, Sb, In and Sn are added to a vacuum melting furnace, heated to 300°C at a heating rate of 20°C / min, kept for 1h, stirred, and then heated to 550°C at a heating rate of 10°C / min, kept for 90 minutes, stirred, and cooled to room temperature at a cooling rate of 20°C / min. The obtained Sn-Sb-In alloy is further mechanically crushed to prepare a powder; S2. The Sn-Sb-In alloy powder, TiH2 powder, Ag powder, Cu powder, Hf powder, Ni powder, Ge powder, Pr powder, Yb powder and La powder are processed by a ball mill, and the powder diameter is 50μm; S3. The mixed ball-milled powder is put into a mold and pressed by a hydraulic machine. The pressed sample is placed in a vacuum furnace for sintering at a vacuum degree of 10 -5 Pa and a sintering temperature of 600°C to obtain the solder. S4. The sintered solder is further rolled and wire cut to obtain a preformed solder sheet.

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