Medium temperature lead-containing solder and preparation method and application thereof

Abstract

The application belongs to the technical field of brazing, and particularly relates to a medium-temperature lead-containing filler metal and a preparation method and application thereof. The medium-temperature lead-containing filler metal comprises Ag, Sn, Sb and Pb elements and essential impurity elements, wherein the mass percentage of the Ag element is 0.5-2%, the mass percentage of the Sn element is 5-15%, and the mass percentage of the Sb element is 5-15%. Metal raw materials containing the elements are mixed and melted to obtain the medium-temperature lead-containing filler metal. The filler metal is used in a welding product in the field of electronic packaging. The welding interface of the welding product has reliable connection strength, and the interface is continuous and has good consistency. In addition, the welding product has strong applicability to external environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of brazing, and particularly relates to a medium-temperature lead-containing brazing filler metal and a preparation method and application thereof. BACKGROUND

[0002] The solder joint is a key part for connecting the components of a product, and is not only used for electrical and mechanical connection, but also provides a heat dissipation channel for the chip, and the reliability of the solder joint determines the quality of the electronic device to a great extent.

[0003] A complex electronic device, such as a chip, usually needs multi-level packaging, in which the eutectic soldering of the chip requires an Au-Sn solder at 280-300℃, and the subsequent BGA soldering requires a SnPb solder at 180-210℃, and thus the soldering of the discrete device can only be completed at 220-260℃. The existing packaging technology, such as the epoxy resin conductive adhesive packaging process, can play a role in electrical and mechanical connection, and has various advantages, such as environmental friendliness, mild process conditions, and simple process, but can only be used for packaging non-power chips, and is not suitable for packaging power devices, circulators and connectors. For the packaging of these devices, the soldering process is the most mature and most commonly used packaging technology. For the soldering temperature of 220-260℃, the commonly used soldering filler metals include lead-free soldering filler metals Sn 96.5 Ag 3.5 / Sn 96.5 Ag3Cu 0.5 The soldering filler metal belongs to a tin-based alloy, and the crystal lattice type of tin is polymorphic organization, including three crystal lattice morphologies of white tin, gray tin and brittle tin. The white tin (β-Sn) is metallic, the atoms are combined by metal bonds, and the plasticity is high; and the gray tin (α-Sn) is non-metallic, the atoms are combined by covalent bonds, and the brittleness is great, and can be self-fragmented into powder. When the temperature is reduced to below 13℃, the white tin begins to transform into gray tin, at this time, the volume increases by 25.6%, which causes internal stress in the tin to cause it to crack, which is commonly called "tin plague", and thus the lead-free soldering filler metal Sn 96.5 Ag 3.5 / Sn 96.5 Ag3Cu 0.5 Although the lead-free soldering filler metal can meet the temperature requirement of the soldering process, the tin content can cause tin plague, and the lead-free soldering filler metal cannot be applied to occasions with high reliability requirements, such as low-temperature environments.

[0004] Therefore, it is urgent to develop a soldering filler metal with strong external environment applicability, a soldering temperature of 220-260℃, and a reliable connection strength and a continuous and good consistency of the soldering interface after soldering in the prior art. SUMMARY

[0005] The technical purpose of the present application is to at least solve the problems of poor environmental applicability of the existing solder, and the soldering product cannot form a reliable connection strength, a continuous and good consistent soldering interface when the soldering temperature is between 220-260℃.

[0006] The purpose is achieved by the following technical solutions:

[0007] In a first aspect, the present application provides a medium-temperature lead-containing solder, which comprises the following components in mass percentage:

[0008] Ag element: 0.5-2%;

[0009] Sn element: 5-15%;

[0010] Sb element: 5-15%;

[0011] Pb element and essential impurities.

[0012] The solder composed of the above-mentioned elements and corresponding contents has high strength and suitable melting point, which is beneficial to form a soldering interface with reliable connection strength and continuous and consistent interface after soldering the soldering product.

[0013] In some embodiments of the present application, the solder further comprises one or two or more of Co element, Au element, Ni element or Ge element.

[0014] In some embodiments of the present application, the mass percentage of the Co element is 0.01-0.05%, the mass percentage of the Au element is 0.01-10%, the mass percentage of the Ni element is 0.03-0.9%, and the mass percentage of the Ge element is 0.01-1%.

[0015] In some embodiments of the present application, the mass percentage of the Co element is 0.02-0.05%, the mass percentage of the Au element is 1-7%, the mass percentage of the Ni element is 0.05-0.5%, and the mass percentage of the Ge element is 0.01-0.08%.

[0016] In some embodiments of the present application, the mass percentage of the Co element is 0.02-0.03%, the mass percentage of the Au element is 2-4%, the mass percentage of the Ni element is 0.3-0.5%, and the mass percentage of the Ge element is 0.03-0.05%.

[0017] In some embodiments of the present application, the mass percentage of the Ag element is 0.8-1.5%, which can be further preferably 1.0-1.5%.

[0018] In some embodiments of the present application, the mass percentage of the Sn element is 8-12%, which can be further preferably 9-11%.

[0019] In some embodiments of the present application, the mass percentage of the Sb element is 8-12%, which can be further preferably 9-11%.

[0020] In some embodiments of the present application, the solder contains the following components in mass percentage:

[0021] Ag element: 1.0-1.5%;

[0022] Sn element: 9-11%;

[0023] Sb element: 9-11%;

[0024] Co element: 0.02-0.03%;

[0025] Au element: 2-4%;

[0026] Ni element: 0.3-0.5%;

[0027] Ge element: 0.03-0.05%;

[0028] The rest is Pb element and inevitable impurities.

[0029] Among them, the solder containing appropriate amounts of Co element, Au element, Ni element and Ge element is more beneficial to the welding of the welding product, such as more beneficial to form a welding interface with reliable connection strength, and continuous and consistent interface, at the same time, due to the control of the tin element content, there is no risk of tin pest, so the welding product has strong external environment applicability.

[0030] In a second aspect, the present application provides a preparation method of the medium-temperature lead-containing solder of the first aspect, and the preparation method comprises:

[0031] According to the content of each element, the corresponding raw materials are mixed and melted to obtain the medium-temperature lead-containing solder.

[0032] In some embodiments of the present application, the preparation method comprises the following processes:

[0033] Batching: according to the mass percentage, each metal raw material is configured respectively, and the metal raw materials are divided into two groups, one group containing Sn element and Sb element, and the other group containing Ag element and Pb element;

[0034] Melting: the metal raw materials containing Sn element and Sb element are vacuum melted to melt and mixed to form an alloy A with uniform composition;

[0035] vacuum melting the metal raw material containing Ag element and Pb element to melt, mixing to form an alloy B with uniform composition;

[0036] vacuum melting the alloy A, the alloy B and the metal Pb raw material, covering the surface of the molten alloy with an anti-oxidation solvent, mixing and holding to obtain an alloy melt;

[0037] processing and forming: pouring the alloy melt to form a middle-temperature lead-containing solder ingot blank.

[0038] In some embodiments of the present application, the ingredients further comprise grouping metal raw materials containing one or two or more of Co element, Au element, Ni element or Ge element; the melting further comprises vacuum melting the metal raw materials containing one or two or more of Co element, Au element, Ni element or Ge element to melt, mixing to form an alloy C, and vacuum melting the alloy A, the alloy B, the alloy C and the metal Pb raw material.

[0039] In some embodiments of the present application, the vacuum melting comprises vacuumizing the vacuum melting equipment, and then introducing inert gas into the vacuum melting equipment.

[0040] In some embodiments of the present application, the vacuumizing of the vacuum melting equipment is to a relative vacuum degree of 1×10 - 1 Pa.

[0041] In some embodiments of the present application, the anti-oxidation solvent comprises any one of rosin or halide salt, and the halide salt comprises sodium chloride, potassium chloride, lithium chloride, zinc chloride, etc.

[0042] In some embodiments of the present application, the preparation method further comprises converting the middle-temperature lead-containing solder ingot blank into at least one of paste, tape, foil, sheet, wire or powder.

[0043] In a third aspect, the present application discloses a welding method of a welding product, which comprises placing a solder between a first structure to be welded and a second structure to be welded, wherein the solder is the solder of the first aspect or the solder prepared by the method of the second aspect;

[0044] soldering the solder to connect the first structure to be welded and the second structure to be welded, wherein the first structure to be welded can be a substrate, and the second structure to be welded can be a discrete device, and the first structure to be welded and the second structure to be welded can also be other devices in the field of integrated circuits.

[0045] In some embodiments of the present application, the soldering temperature is 220-260℃.

[0046] In some embodiments of the present application, the brazing temperature is 230-250°C.

[0047] In a fourth aspect, the present application discloses a welded product, which is obtained by the method of the third aspect. The welded product has good quality of the welding interface, and the welded product has strong applicability to external environment.

[0048] The beneficial effects of the technical solutions of the present application mainly include the following:

[0049] The present application provides a medium-temperature lead-containing solder, a preparation method and application thereof. The welding temperature of the medium-temperature lead-containing solder is 220-260°C. The welding interface obtained at the welding temperature has reliable connection strength, and the interface is continuous and has good consistency. In addition, the welding product containing the welding interface has strong applicability to external environment, such as not affecting the interface performance at low temperature. The solder is suitable for the field of integrated circuits. BRIEF DESCRIPTION OF DRAWINGS

[0050] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments and are not meant to limit the present application.

[0051] Figure 1 DSC spectrum of the solder prepared for some embodiments of the present application;

[0052] Figure 2 Micrograph of the welding interface of the solder prepared for some embodiments of the present application. DETAILED DESCRIPTION

[0053] In the prior art, for complex electronic devices such as chips, multi-level packaging is usually required. The eutectic welding of the chip requires Au-Sn solder at 280-300°C, and the subsequent BGA welding requires SnPb solder at 180-210°C. Therefore, the welding of discrete devices can only be completed at 220-260°C. The existing packaging technology such as epoxy resin conductive adhesive packaging process can play the role of circuit connection and mechanical connection, and has many advantages such as environmental friendliness, mild process conditions, and relatively simple process. However, it can only be used for packaging non-power chips, and is not suitable for packaging power devices, circulators and connectors. For the packaging of these devices, the solder welding process is the most mature and most commonly used packaging technology. For the solder with a welding temperature of 220-260°C, commonly used include lead-free solder Sn 96.5 Ag 3.5 / Sn 96.5 Ag3Cu 0.5 However, lead-free solder Sn 96.5 Ag 3.5 / Sn 96.5 Ag3Cu 0.5 Although it can meet the temperature requirements of the soldering process, it cannot be applied to occasions with high reliability requirements, such as low-temperature environments.

[0054] To solve the above technical problems, the application provides a medium-temperature lead-containing solder, a preparation method and application thereof. The medium-temperature lead-containing solder can form reliable connection strength and continuous, good and consistent welding interface after welding of a welding product. In addition, the welding product containing the welding interface has strong applicability to external environment, and will not affect the interface performance at low temperature.

[0055] The first aspect of the application to achieve the above technical effects is to provide a medium-temperature lead-containing solder. The solder contains Ag element, Sn element, Sb element and Pb element and essential impurities. The mass percentage of the Ag element is 0.5-2%, the mass percentage of the Sn element is 5-15%, and the mass percentage of the Sb element is 5-15%. The essential impurities herein include essential impurity elements in each metal raw material, and the impurity elements have almost no effect on the welding temperature and interface quality of the solder of the application, which will not be described in detail.

[0056] In some embodiments, the mass percentage of the Ag element is 0.8-1.5%, which can be further preferred to be 1.0-1.5%.

[0057] In some embodiments, the mass percentage of the Sn element is 8-12%, which can be further preferred to be 9-11%.

[0058] In some embodiments, the mass percentage of the Sb element is 8-12%, which can be further preferred to be 9-11%.

[0059] For example, the mass percentage of the Ag element is any one of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0% or any value meeting the above range.

[0060] For example, the mass percentage of the Sn element is any one of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or any value meeting the above range.

[0061] For example, the mass percentage of the Sb element is any one of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or any value meeting the above range.

[0062] For example, the mass percentage of the Pb element is any one of 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88% or any value within the above range.

[0063] In some embodiments, the solder further comprises one or two or more of Co element, Au element, Ni element or Ge element.

[0064] In some embodiments, the mass percentage of the Co element is 0.01-0.05%, preferably 0.02-0.05%, more preferably 0.02-0.03%.

[0065] In some embodiments, the mass percentage of the Au element is 0.01-10%, preferably 1-7%, more preferably 2-4%.

[0066] In some embodiments, the mass percentage of the Ni element is 0.03-0.9%, preferably 0.05-0.5%, more preferably 0.3-0.5%.

[0067] In some embodiments, the mass percentage of the Ge element is 0.01-1%, preferably 0.01-0.08%, more preferably 0.03-0.05%.

[0068] For example, the mass percentage of the Co element is any one of 0.01%, 0.02%, 0.03%, 0.04%, 0.05% or any value within the above range.

[0069] For example, the mass percentage of the Au element is any one of 0.01%, 0.05%, 0.10%, 0.20%, 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10% or any value within the above range.

[0070] For example, the mass percentage of the Ni element is any one of 0.03%, 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9% or any value within the above range.

[0071] For example, the mass percentage of the Ge element is any one of 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%, 1.0% or any value within the above range.

[0072] In a second aspect, the present application provides a preparation method of a medium-temperature lead-containing solder, which comprises mixing and melting metal raw materials containing Ag element, Sn element, Sb element and Pb element to obtain the medium-temperature lead-containing solder, wherein the mass percentage of the Ag element is 0.5-2%, the mass percentage of the Sn element is 5-15%, the mass percentage of the Sb element is 5-15%, and the mass percentage of the Pb element is 68-88%. Specifically, the mass percentages of the Ag element, Sn element, Sb element and Pb element satisfy the description in the first aspect, which will not be described in detail here.

[0073] In some embodiments, the method comprises the following preparation steps:

[0074] 1) batching: according to the mass percentages, respectively configure each metal raw material, and divide the metal raw materials into two groups, one group containing Sn element and Sb element, and the other group containing Ag element and Pb element;

[0075] 2) smelting: comprising the following steps:

[0076] 2.1) vacuum smelting the metal raw materials containing Sn element and Sb element to melt, and uniformly mixing to form alloy A with uniform composition;

[0077] 2.2) vacuum smelting the metal raw materials containing Ag element and Pb element to melt, and uniformly mixing to form alloy B with uniform composition;

[0078] 2.3) vacuum smelting the alloy A prepared in step 2.1), the alloy B prepared in step 2.2) and metal Pb to melt, covering the surface of the molten alloy with an anti-oxidation solvent, uniformly mixing and heat-insulating to obtain an alloy melt;

[0079] 3) processing forming: pouring the alloy melt prepared in step 2.3) to form a medium-temperature lead-containing solder ingot.

[0080] In some embodiments, the solder further comprises one or two or more of Co element, Au element, Ni element or Ge element, and the mass percentage of the Co element, Au element, Ni element and Ge element satisfies the description of the first aspect, which is not described in detail here.

[0081] In some embodiments, when the solder further comprises one or two or more of Co element, Au element, Ni element or Ge element, the preparation method further comprises the following:

[0082] The step 1) comprises dividing the metal raw materials into three groups, one group comprising Sn element and Sb element, another group comprising Ag element and Pb element, and the remaining group comprising Sn element and one or two or more of Co element, Au element, Ni element or Ge element;

[0083] The step 2) further comprises vacuum melting the metal raw materials comprising Sn element and one or two or more of Co element, Au element, Ni element or Ge element to melt, and mixing to form an alloy C with uniform composition; and further comprises melting alloy A, alloy B, alloy C and metal Pb in a melting furnace.

[0084] In some embodiments, the vacuum melting in step 2) comprises vacuumizing the vacuum melting equipment to a relative vacuum degree of 1x10 -1 Pa.

[0085] Illustratively, the vacuum melting equipment comprises a vacuum melting furnace, and any model of the vacuum melting furnace meets the requirements of the present application, which is not described in detail here.

[0086] In some embodiments, after the vacuum treatment is completed, inert gas is introduced into the vacuum melting equipment.

[0087] Illustratively, the vacuum melting equipment is filled with inert gas, which is used to drive out the oxygen-containing gas in the vacuum melting equipment.

[0088] In some embodiments, the anti-oxidation solvent comprises any one of rosin or halide salt, and the halide salt comprises sodium chloride, potassium chloride, lithium chloride, zinc chloride, etc.

[0089] In some embodiments, the mixing method comprises stirring, and the stirring comprises mechanical stirring and / or electromagnetic stirring.

[0090] In some embodiments, each of the metal raw materials has an industrial purity, such as 1 nine or more, preferably 2 nines.

[0091] In some embodiments, the preparation method further comprises converting the intermediate-temperature lead-containing solder ingot prepared in step 3) into at least one of a paste, a tape, a foil, a sheet, a wire or a powder.

[0092] For example, the converting comprises using a powdering device and a process, a wire-making device and a process, a sheet-making device and a process, etc. which are conventional in the art.

[0093] For example, the powdering device and the process comprise a centrifugal atomization powdering device and a process which are conventional in the art.

[0094] For example, the wire-making device and the process comprise a wire-drawing device and a process which are conventional in the art.

[0095] For example, the sheet-making device and the process comprise a solder sheet preparation process and a device which are conventional in the art.

[0096] For the above-mentioned converting modes, no further description is made herein.

[0097] In a third aspect, the present application discloses a soldering method of a soldering product, which comprises placing a solder between a first structure to be soldered and a second structure to be soldered, wherein the solder is the solder of the first aspect or the solder prepared by the method of the second aspect.

[0098] The solder is soldered to connect the first structure to be soldered and the second structure to be soldered, wherein the first structure to be soldered can be a substrate, and the second structure to be soldered can be a discrete device. The first structure to be soldered and the second structure to be soldered can also be other devices in the field of integrated circuits, wherein the substrate and the discrete device are conventional choices in the field of integrated circuits, and no further description is made herein.

[0099] In some embodiments of the present application, the soldering temperature is 220-260°C.

[0100] In some embodiments of the present application, the soldering temperature is 230-250°C.

[0101] In a fourth aspect, the present application discloses a soldering product, which is obtained by the method of the third aspect. The soldering product has good soldering interface quality, and has strong adaptability to external environment.

[0102] Exemplary embodiments of the present application will be described in greater detail below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it is understood that the present application can be embodied in various forms without being limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0103] Embodiments 1 to 23

[0104] A medium-temperature lead-containing solder is disclosed, wherein the elemental content (wt%) of each embodiment is shown in Table 1;

[0105] Table 1 Elemental content (wt%) in each embodiment

[0106]

[0107] The preparation method is described in detail taking Embodiment 5 and Embodiment 12 as examples, and specifically as follows:

[0108] Embodiment 5

[0109] A preparation method of a medium-temperature lead-containing solder is disclosed, specifically comprising the following preparation steps:

[0110] 1) batching: according to the mass percentage, each metal raw material is configured respectively, and the metal raw materials are divided into two groups, one group comprising Sn element and Sb element, and the other group comprising Ag element and Pb element; and the purity of each metal raw material is 99.99wt.%;

[0111] 2) smelting: comprising the following steps:

[0112] 2.1) the metal raw materials comprising Sn element and Sb element are placed in a vacuum smelting furnace, the vacuum smelting furnace is pre-vacuumized to 1×10 -1 Pa and filled with nitrogen, to ensure that the smelting is completed in an oxygen-free environment, the alloy is melted by heating, and electromagnetic stirring is additionally added to make the alloy composition uniform, to obtain a SnSb50 intermediate alloy;

[0113] 2.2) the metal raw materials comprising Ag element and Pb element are placed in the same environment vacuum smelting furnace as described in step 2.1), the alloy is melted by heating, and electromagnetic stirring is additionally added to make the alloy composition uniform, to obtain a PbAg50 intermediate alloy;

[0114] 2.3) according to a certain ratio, melting the SnSb50 intermediate alloy prepared in step 2.1), the PbAg50 intermediate alloy prepared in step 2.2) and the metal Pb in a vacuum melting furnace, covering the surface of the molten alloy with an anti-oxidation solvent rosin, stirring and mixing, heating to 400℃, maintaining for 10-20 min, continuously stirring to remove the surface oxidation slag, obtaining an alloy melt;

[0115] 3) processing and forming: pouring the alloy melt prepared in step 2.3) into a mold to form a medium-temperature lead-containing solder ingot blank.

[0116] The ingot blank is used to prepare SnPbSbAg welding powder by a centrifugal atomization powder preparation process, wherein the DSC spectrum of the welding powder is as shown in Figure 1 , and it can be seen from Figure 1 that the melting point of the welding powder is 235-238℃. The thermal analyzer of DSC is a conventional instrument in the art, and no special description is made.

[0117] The above welding powder is used to weld a substrate and a chip, and the welding temperature satisfies 220-260℃, and the micrograph of the welding interface is as shown in Figure 2 , and it can be seen from Figure 2 that the interface is continuous and has good quality. The specific quality is shown in Table 2.

[0118] Example 12

[0119] A preparation method of a medium-temperature lead-containing solder is disclosed, specifically comprising the following preparation steps:

[0120] 1) batching: respectively configuring each metal raw material according to the mass percentage, dividing the metal raw materials into three groups, one group containing Sn elements and Sb elements, another group containing Ag elements and Pb elements, and the remaining group containing Sn elements and Ni elements; and the purity of each metal raw material is 99.99wt.%;

[0121] 2) melting: comprising the following steps:

[0122] 2.1) placing the metal raw materials containing Sn elements and Sb elements in a vacuum melting furnace, the vacuum melting furnace is pre-treated to 1×10 -1 Pa and filled with nitrogen, ensuring that the melting is completed in an oxygen-free environment, heating to melt the alloy, and simultaneously adding electromagnetic stirring to make the alloy composition uniform, to prepare a SnSb50 intermediate alloy;

[0123] 2.2) placing the metal raw materials containing Ag elements and Pb elements in the same environment vacuum melting furnace as described in step 2.1), heating to melt the alloy, and simultaneously adding electromagnetic stirring to make the alloy composition uniform, to prepare a PbAg50 intermediate alloy;

[0124] The metal raw material containing Sn element and Ni element is placed in the vacuum melting furnace in the same environment as described in step 2.1), and the alloy is melted by heating, while electromagnetic stirring is added to make the alloy composition uniform, to obtain a SnNi5 intermediate alloy;

[0125] 2.3) The SnSb50 intermediate alloy prepared in step 2.1), the PbAg50 intermediate alloy prepared in step 2.2), the SnNi5 intermediate alloy, and the metal Pb are mixed in a certain ratio in a vacuum melting furnace, the surface of the molten alloy is covered with an anti-oxidizing solvent sodium chloride, and the mixture is stirred and heated to 400°C for 10-20 min. Continue to stir and remove the surface oxidation slag to obtain an alloy melt;

[0126] 3) Processing and forming: The alloy melt prepared in step 2.3) is poured into a mold to form a medium-temperature lead-containing solder ingot blank.

[0127] The ingot blank is made into a SnPbSbAgNi solder sheet using a solder sheet preparation process; the solder sheet is used to weld the soldered product, and the welding interface quality is shown in Table 2.

[0128] Table 2: Welding quality list of solder joints

[0129] Solder form Solder melting range (°C) Weld hardness (HL) Strength (MPa) Weld interface Example 1 Wire 230-250 345 85 Continuous, good, consistent Example 2 Sheet 236-245 280 70 Continuous, good, consistent Example 3 Powder 220-232 340 84 Continuous, good, consistent Example 4 Powder 220-234 275 69 Continuous, good, consistent Example 5 Wire 235-238 300 80 Continuous, good, consistent Example 6 Powder 230-236 291 78 Continuous, good, consistent Example 7 Sheet 225-240 305 81 Continuous, good, consistent Example 8 Wire 225-242 310 82 Continuous, good, consistent Example 9 Powder 220-245 332 83 Continuous, good, consistent Example 10 Wire 232-253 335 86 Continuous, good, consistent Example 11 Sheet 236-258 270 67 Continuous, good, consistent Example 12 Powder 236-240 290 72 Continuous, good, consistent Example 13 Powder 225-250 330 83 Continuous, good, consistent Example 14 Wire 232-236 326 82 Continuous, good, consistent Example 15 Powder 236-248 325 82 Continuous, good, consistent Example 16 Wire 225-255 275 69 Continuous, good, consistent Example 17 Sheet 235-250 309 82 Continuous, good, consistent Example 18 Powder 236-240 310 82 Continuous, good, consistent Example 19 Wire 246-253 325 83 Continuous, good, consistent Example 20 Powder 246-250 320 82 Continuous, good, consistent Example 21 Sheet 235-240 345 86 Continuous, good, consistent Example 22 Powder 234-236 340 87 Continuous, good, consistent Example 23 Powder 232-235 341 86 Continuous, good, consistent

[0130] The melting point of the solder in Table 2 is tested by a melting point tester, model NETZSBH STA 409PB / PG type differential scanning calorimeter (DSC) to analyze the sample melting characteristics, protected by Ar gas, and the temperature rise is set to 10K / min.

[0131] The hardness (HL) of the solder joint is one of the indicators to characterize the performance of the material. The Leeb-140 type Rockwell hardness tester is used to test the hardness of the solder alloy ingot.

[0132] The tensile strength sample is a sheet sample, and the prepared solder alloy is processed by wire cutting. The loading method and loading rate are in accordance with JIS-Z-2241 requirements (strain rate 0.5mm / min). The test temperature is specified as 23±5℃. The original area, gauge length, force, and tensile strength are measured and calculated according to JIS-Z-2241.

[0133] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order

[0134] The above description is only preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A medium-temperature lead-containing brazing filler metal, characterized in that, The solder comprises the following components by weight percentage: Ag element: 1.0~1.5%; Sn element: 9~11%; Sb element: 9~11%; Co element: 0.02~0.03%; Au element: 2~4%; Ni element: 0.3~0.5%; Ge element: 0.03~0.05%; Pb element and essential impurities.

2. A method for preparing the medium-temperature lead-containing solder as described in claim 1, characterized in that, The preparation method includes: The intermediate-temperature lead-containing brazing filler metal is obtained by mixing and melting the corresponding raw materials according to the content of each element.

3. The preparation method according to claim 2, characterized in that, The preparation method includes the following steps: Ingredients: Each metal raw material is prepared according to the mass percentages mentioned above. The metal raw materials are divided into two groups: one group contains Sn and Sb elements, and the other group contains Ag and Pb elements. Smelting: The metal raw materials containing Sn and Sb elements are vacuum smelted until melted and mixed to form alloy A; Metal raw materials containing Ag and Pb elements are vacuum melted until melted and mixed to form alloy B. Alloy A, Alloy B and Pb raw material are vacuum melted, and an anti-oxidation solvent is covered on the surface of the molten alloy. The mixture is then stirred and kept at a constant temperature to obtain an alloy melt. Processing and forming: The alloy melt is poured to form a medium-temperature lead-containing brazing filler metal ingot; The ingredients also include grouping metal raw materials containing Co, Au, Ni and Ge elements; the smelting also includes vacuum smelting the metal raw materials containing Co, Au, Ni and Ge elements until they melt, mixing them to form alloy C, and vacuum smelting the alloy A, the alloy B, the alloy C and the metal Pb raw material.

4. The preparation method according to claim 3, characterized in that, The vacuum melting process includes evacuating the vacuum melting equipment and then introducing an inert gas into the equipment; the relative vacuum level is 1×10⁻⁶. -1 Pa; The antioxidant solvent comprises either rosin or a halide salt, wherein the halide salt comprises sodium chloride, potassium chloride, lithium chloride, or zinc chloride.

5. The preparation method according to claim 3, characterized in that, The preparation method further includes converting the medium-temperature lead-containing brazing filler metal blank into at least one of paste, strip, foil, sheet, wire, or powder.

6. A welding method for a welded product, characterized in that, The welding method includes placing a brazing filler metal between a first structure to be welded and a second structure to be welded, wherein the brazing filler metal is the brazing filler metal of claim 1 or the brazing filler metal prepared by the method of any one of claims 2 to 5; The brazing filler metal is used to connect the first structure to be welded to the second structure to be welded. The brazing temperature is 220~260℃.

7. A welding product, characterized in that, The product is obtained by welding using the method described in claim 6.

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