CN116275685A - Low-temperature soldering tin material for copper substrate, welding assembly, preparation method and application of low-temperature soldering tin material - Google Patents
Low-temperature soldering tin material for copper substrate, welding assembly, preparation method and application of low-temperature soldering tin material Download PDFInfo
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- CN116275685A CN116275685A CN202310214577.1A CN202310214577A CN116275685A CN 116275685 A CN116275685 A CN 116275685A CN 202310214577 A CN202310214577 A CN 202310214577A CN 116275685 A CN116275685 A CN 116275685A
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- 239000010949 copper Substances 0.000 title claims abstract description 79
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 title claims abstract description 70
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 52
- 238000003466 welding Methods 0.000 title claims abstract description 46
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 239000000758 substrate Substances 0.000 title claims abstract description 33
- 238000005476 soldering Methods 0.000 title abstract description 33
- 238000002360 preparation method Methods 0.000 title abstract description 23
- 239000000463 material Substances 0.000 title abstract description 22
- 229910000679 solder Inorganic materials 0.000 claims abstract description 115
- 229910052718 tin Inorganic materials 0.000 claims abstract description 91
- 238000000034 method Methods 0.000 claims abstract description 35
- 230000004888 barrier function Effects 0.000 claims abstract description 27
- 238000004377 microelectronic Methods 0.000 claims abstract description 12
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- 238000002844 melting Methods 0.000 claims description 24
- 230000008018 melting Effects 0.000 claims description 24
- 238000005275 alloying Methods 0.000 claims description 21
- 238000005266 casting Methods 0.000 claims description 14
- 238000002156 mixing Methods 0.000 claims description 10
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- 239000011159 matrix material Substances 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 5
- 239000011888 foil Substances 0.000 claims description 4
- 239000000843 powder Substances 0.000 claims description 4
- 229910000636 Ce alloy Inorganic materials 0.000 claims description 3
- 229910001122 Mischmetal Inorganic materials 0.000 claims description 3
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- 230000015572 biosynthetic process Effects 0.000 abstract description 16
- 238000009792 diffusion process Methods 0.000 abstract description 13
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- 229910017927 Cu—Sn Inorganic materials 0.000 abstract description 8
- 229910052797 bismuth Inorganic materials 0.000 abstract description 8
- 229910052733 gallium Inorganic materials 0.000 abstract description 7
- -1 Cu-Sn compound Chemical class 0.000 abstract description 4
- 230000002401 inhibitory effect Effects 0.000 abstract description 4
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- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 description 11
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- 230000003064 anti-oxidating effect Effects 0.000 description 1
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- 238000000429 assembly Methods 0.000 description 1
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
- B23K35/262—Sn as the principal constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
- B23K35/264—Bi as the principal constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/40—Making wire or rods for soldering or welding
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
The application belongs to the technical field of welding, and particularly relates to a low-temperature soldering tin material for a copper substrate, a welding assembly, a preparation method and application of the low-temperature soldering tin material. The tin solder in the application comprises the following element contents in percentage by mass: 40.0 to 58.0 percent of Bi; 0.1 to 2.0 percent of Ga; the balance of Sn; wherein, when the tin solder is applied to the copper substrate, a Cu-Ga barrier layer is formed at the welding interface. The Cu-Ga barrier layer is used for preventing mutual diffusion between Cu and Sn and inhibiting formation of a Bi-rich layer, and meanwhile, the Cu-Ga barrier layer is good in stability, and even if aging treatment is carried out for a certain time, the Cu-Ga barrier layer at a welding interface is not obviously grown, and the formation of a Cu-Sn compound layer is effectively prevented. The method is favorable for ensuring wettability of a welding interface, has proper interface strength, high reliability of welding spots and long service life, and is suitable for the field of microelectronic packaging.
Description
Technical Field
The application belongs to the technical field of welding, and particularly relates to a low-temperature soldering tin material for a copper substrate, a welding assembly, a preparation method and application of the low-temperature soldering tin material.
Background
With the rapid development of microelectronic technology, microelectronic packaging tends to lead-free, miniaturized, fine-pitch and high-reliability, especially the appearance of high-density packaging technology, the size of welding spots is smaller and smaller, and the packaging structure is more and more complex, so that the requirements on higher mechanical properties and reliability are put on welding spots. At present, the main stream Sn-Ag-Cu solder alloy has high melting point (217 ℃) and high welding temperature, which is easy to cause serious warping of a substrate, causes welding failure, further causes irreversible heat damage of a thermosensitive device, greatly increases the energy consumption of the whole industrial chain, and greatly increases carbon emission, so that the application of the Sn-Ag-Cu solder alloy in the field of microelectronic packaging is gradually limited.
Therefore, the low-temperature solder capable of meeting the micro-electronic interconnection requirements of the new generation of chip packaging and SMT low-temperature manufacturing process becomes the development trend of the micro-electronic interconnection material in the future. The existing low-temperature solder, such as Sn-Bi alloy, is easy to generate intermetallic compounds with Cu element in a Cu substrate in the welding process, element segregation is caused, the welding spot is embrittled and invalid, and the welding spot has short service life and low reliability.
Disclosure of Invention
The technical purpose of the application is to at least solve the problems of short service life, low reliability and the like of welding spots, which are easy to cause embrittlement and failure of welding spots when the prior Sn-Bi alloy is welded on a Cu substrate.
The aim is achieved by the following technical scheme:
in a first aspect, the present application provides a low temperature tin solder for copper substrates, the tin solder comprising the following element contents in mass percent:
Bi:40.0％～58.0％；
Ga:0.1％～2.0％；
the balance of Sn;
wherein the tin solder forms a Cu-Ga barrier layer at a solder interface when applied to the copper substrate. The Cu-Ga barrier layer comprises a Cu-Ga intermetallic compound, wherein the Cu-Ga barrier layer is used for preventing mutual diffusion between Cu and Sn and inhibiting formation of a Bi-rich layer, meanwhile, the Cu-Ga barrier layer is good in stability, and even if aging treatment is carried out for a certain time, the Cu-Ga barrier layer at a welding interface is not obviously grown, and formation of a Cu-Sn compound layer is effectively prevented.
In some embodiments of the present application, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～2.0％；
the balance being Sn.
In some embodiments of the present application, the tin solder further comprises an alloying element, wherein the mass percentage content of the alloying element satisfies:
alloying elements are more than 0 and less than or equal to 2.0 percent;
(1) And the alloying element comprises one or two or more of Sb, cu, in, ag, ni, zn, a misch metal comprising a lanthanum-cerium alloy. The alloying elements can optimize the toughening matching relation of the solder through the effects of solid solution strengthening, second phase particle strengthening, fine grain strengthening and the like, and further improve the reliability of the solder.
In some embodiments of the present application, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
0.1 to 1.5 percent of alloying element; the alloying element comprises one or two or more of Sb, cu, in, ag, ni, zn;
the balance of Sn;
and the eutectic melting point of the tin solder is 130-150 ℃.
In a second aspect, the present application provides a method for preparing the low-temperature tin solder according to the first aspect, where the preparation method includes: and mixing and melting corresponding raw materials according to the content of each element, casting to form an ingot blank, and converting the ingot blank into any one of paste, tape, foil, sheet, wire, powder or ball.
In a third aspect, the present application provides a copper-based solder assembly, the solder assembly comprising a copper substrate and a solder layer on the surface of the copper substrate, the solder layer being soldered by the low temperature solder of the first aspect or the low temperature solder prepared by the method of the second aspect.
In some embodiments of the present application, a portion of the elemental Ga in the tin solder forms a Cu-Ga barrier layer, with the remainder of the elemental Ga forming a Ga-rich phase and being distributed in the Sn matrix in a network or precipitated at Sn phase boundaries. On one hand, the Ga-rich phase plays a role in refining grains for improving the strength and toughness of the solder, and on the other hand, the Ga-rich phase separated out at the grain boundary inhibits the growth of Sn phase in the aging process, so that the growth rate of intermetallic compounds is further reduced, and the reliability of the solder is improved.
In some embodiments of the present application, the Cu-Ga barrier layer has a thickness of 1 μm to 8 μm, preferably 1.5 μm to 7.0 μm. Among these, cu-Ga barrier layers of suitable thickness are advantageous for weld life.
In a fourth aspect, the present application provides a method for preparing the assembly according to the third aspect, including:
the low-temperature tin solder is heated and melted to form molten liquid;
and the copper substrate is contacted with the molten liquid to obtain a tin welding layer.
In a fifth aspect, the present application provides a low-temperature tin solder prepared by the method according to the first aspect or the low-temperature tin solder prepared by the method according to the second aspect or the copper-based soldered component prepared by the method according to the third aspect or the copper-based soldered component prepared by the method according to the fourth aspect, for use in microelectronic packaging. The microelectronics are conventional components and the like in the art.
The beneficial effects of the technical scheme disclosed by the application are mainly shown as follows:
1. the tin solder provided by the application has the advantages of uncomplicated self components, simple preparation process, suitability for welding copper plates, good wettability of a welding interface, proper interface strength, high reliability of welding spots and long service life.
2. The tin solder provided by the application is suitable for the field of microelectronic packaging.
Drawings
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 drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 schematically shows a microstructure and elemental distribution diagram at a Cu substrate bonding interface according to an embodiment of the present application, wherein (a) the microstructure at the bonding interface; (b) Sn elemental profile; (c) Ga elemental profile; (d) Cu element profile;
FIG. 2 schematically illustrates a microstructure and elemental distribution diagram at a Cu substrate bonding interface according to an embodiment of the present application, wherein (a) the microstructure at the bonding interface; (b) Sn elemental profile; (c) Ga elemental profile; (d) Cu element profile;
FIG. 3 schematically shows the microstructure and elemental distribution pattern at the Cu substrate bonding interface in the comparative example, wherein (a) the microstructure at the bonding interface; (b) Sn elemental profile; (c) Bi elemental profile; (d) Cu element profile;
FIG. 4 schematically shows a microstructure and element distribution diagram of a Cu substrate weld interface after 100 ℃ by 480h aging treatment according to an embodiment of the present application, wherein (a) the microstructure at the weld interface after aging treatment; (b) Sn elemental profile; (c) Ga elemental profile; (d) Cu element profile;
FIG. 5 schematically shows a microstructure and element distribution diagram of a Cu substrate welded interface after aging treatment at 100 ℃ for 480 hours in a comparative example, wherein (a) the microstructure at the welded interface after aging treatment; (b) Sn elemental profile; (c) Bi elemental profile; (d) Cu element profile;
fig. 6 schematically shows a microstructure scanning electron microscope image of an alloy according to an embodiment of the present application.
Detailed Description
In the prior art, the eutectic composition of the Sn-Bi alloy is Sn-58Bi (wt.%), the eutectic temperature is 138 ℃, and the Sn-Bi alloy has the advantages of excellent wettability, high strength, low cost and the like, and has great potential in the fields of thermosensitive devices, SMT packaging and the like. Due to the inherent brittleness of Bi, the reasonable reduction of the Bi content can obviously improve the plasticity of the alloy on the premise of not losing the strength of the alloy, but the reduction of the Bi content can deteriorate the wettability, cause the rise of the melting point and obviously increase the melting range. The Sn-Bi solder with good comprehensive performance can be obtained by comprehensively considering the strength, plasticity, melting characteristic and wettability of the solder alloy, wherein the mass percentage of Bi is 40% -58%.
When the Sn-Bi solder is soldered to a Cu substrate, an intermetallic compound is formed between Sn element and Cu element at the soldering interface, and Bi element segregation is caused by the loss of Sn element in the solder, so that a Bi-rich layer is formed near the soldering interface. Due to the inherent brittleness of the Bi-rich phase, the formation of the Bi-rich layer at the weld interface and the growth of the Bi-rich layer during subsequent aging often become a weak area of the weld spot, and cracks easily initiate and propagate at the weld interface and eventually cause the weld spot to fail. The formation of Bi-rich phases is thought to be mainly caused by the interdiffusion of Cu and Sn at the solder interface. The mutual diffusion of Cu and Sn at the welding interface causes the thickening of an intermetallic compound layer at the welding interface, and meanwhile, a large amount of Bi phase is left at the welding interface and grows up due to the large atomic number and slow diffusion speed of Bi, so that a Bi-rich layer is finally formed. Therefore, the formation and growth kinetics process of the Bi-rich layer can be inhibited by preventing mutual diffusion of Cu and Sn elements at the welding interface, so that the reliability of the welding spot is improved.
At present, an alloying control microstructure method is generally adopted to inhibit mutual diffusion of Cu and Sn elements, so that the growth speed of intermetallic compounds at a welding interface is reduced, and finally, the purposes of inhibiting the formation of a Bi-rich layer and improving the reliability of welding spots are realized. Common Sn-Bi based alloys include: cu, sb, in, ag, ni, zn, RE (rare earth element), etc.
Specifically, a small amount of Cu element is added into the solder, so that the Cu concentration difference at two sides of a welding interface can be reduced, and the diffusion of Cu and Sn is inhibited; preferably, the mass percentage of Cu element is 0-2.0%.
The Sb element is dissolved in the Bi phase to replace part of Bi atoms, plays a role in solid solution strengthening, inhibits the diffusion of the Bi atoms, and prevents the Bi phase from growing up and the Bi-rich layer from forming; preferably, the mass percentage of the Sb element is 0-2.0%.
In element can replace Cu 6 Sn 5 Part of Sn atoms in the phase forming Cu 6 (Sn,In) 5 Preventing Cu from dissolving into solder, and reducing the thickness of Cu-Sn intermetallic compound; preferably, the mass percentage of the In element is 0 to 2.0%.
Ag formed by Ag element and Sn matrix 3 The Sn phase provides heterogeneous nuclear spots, refines eutectic structures and delays the growth rate of Cu-Sn intermetallic compounds; preferably, the mass percentage of Ag element is 0-2.0%.
Ni element can replace part of Cu 6 Sn 5 Cu atoms in the phase, forming (Cu, ni) 6 Sn 5 The addition of a small amount of Ni element can obviously improve Cu 6 Sn 5 The scallop structure of the phase improves the solder reliability; in addition, the Ni atoms dissolved in the Bi matrix can effectively inhibit Bi atoms from diffusing, inhibit Bi phase growth and inhibit the formation of a Bi-rich layer. Preferably, the mass percentage of Ni element is 0-2.0%.
Therefore, a proper amount of Sb, cu, in, ag, zn and other elements can form intermetallic compounds with Sn to play a role in strengthening second-phase particles, and the strength of the solder is greatly improved and the reliability of the welding spot is improved on the premise of not damaging plasticity.
However, the method for regulating and controlling the microstructure by alloying can only slow down the growth speed of intermetallic compounds at the interface to a certain extent, and can not fundamentally inhibit the formation of the Bi-rich layer and improve the reliability of welding spots.
Therefore, improving the diffusion characteristics of intermetallic compounds at the weld interface of Cu and Sn elements, suppressing the mutual diffusion of Cu and Sn elements is a key to reducing the growth rate of intermetallic compounds, improving the interface morphology, suppressing the formation of Bi-rich layers, and improving the weld reliability of Sn-Bi alloy.
In order to solve the technical problems, the application provides a low-temperature soldering tin material for a copper substrate, a soldering assembly, a preparation method and application thereof, wherein Ga element is firstly added into Sn-Bi solder, a part of Ga element preferentially reacts with Cu to form a compact Cu-Ga barrier layer at a soldering interface, the Cu-Ga barrier layer is used for preventing mutual diffusion between Cu and Sn and inhibiting formation of a Bi-rich layer, meanwhile, the Cu-Ga barrier layer has good stability, and even if aging treatment is carried out for a certain time, the Cu-Ga barrier layer at the soldering interface is not obviously grown, and the formation of a Cu-Sn compound layer is effectively prevented. In addition, the rest part of Ga element generates Ga-rich phase and distributes in a network form in Sn matrix or precipitates at Sn phase grain boundary, the Ga-rich phase plays a role of refining grains for improving strength and toughness of the solder on one hand, and on the other hand, the Ga-rich phase precipitated at the grain boundary inhibits growth of Sn phase in aging process, further reduces growth rate of intermetallic compound, and is beneficial to improving reliability of the solder.
The first aspect of the present application to achieve the above technical effects is to provide a low-temperature tin solder for a copper substrate, where the tin solder includes the following element contents in percentage by mass:
Bi:40.0％～58.0％；
Ga:0.1％～2.0％；
the balance of Sn;
wherein the tin solder forms a Cu-Ga barrier layer at a solder interface when applied to the copper substrate.
And still contain some indispensable impurity elements in the tin solder, these indispensable impurity elements contain the impurity element that is indispensable in each metal raw and other materials, and impurity element is almost not influenced to the welding temperature of this application solder, and interface quality is not described in detail in this application.
In some embodiments, the tin solder comprises the following element contents in mass percent:
Bi:45.0％～58.0％；
Ga:0.5％～2.0％；
the balance being Sn.
Illustratively, the elemental Bi comprises 40.0%, 40.5%, 41.0%, 41.5%, 42.0%, 42.5%, 43.0%, 43.5%, 44.0%, 44.5%, 45.0%, 45.5%, 46.0%, 46.5%, 47.0%, 47.5%, 48.0%, 48.5%, 49.0%, 49.5%, 50.0%, 50.5%, 51.0%, 51.5%, 52.0%, 52.5%, 53.0%, 53.5%, 54.0%, 54.5%, 55.0%, 55.5%, 56.0%, 56.5%, 57.0%, 57.5%, 58.0% by mass or any value satisfying any one of the above range values.
Illustratively, the elemental Ga comprises 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% by mass or any value satisfying the above range of values.
In some embodiments, the tin solder further comprises an alloying element in an amount by mass that satisfies:
alloying elements are more than 0 and less than or equal to 2.0 percent;
and the alloying element comprises one or two or more of Sb, cu, in, ag, ni, zn, a misch metal comprising a lanthanum-cerium alloy.
Illustratively, the mass percent of the alloying element comprises 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%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0% or any value satisfying any of the above range values.
In some embodiments, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
0.1 to 1.5 percent of alloying element; the alloying element comprises one or two or more of Sb, cu, in, ag, ni, zn;
and the eutectic melting point of the tin solder is 130-150 ℃.
In some embodiments, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
Sb/Cu/In/Ag/Ni:0.1％～1.0％；
the balance being Sn.
In some embodiments, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
In:0.1％～0.8％；
Ag:0.1％～0.8％；
the balance being Sn.
In some embodiments, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
Cu:0.8％～1.5％；
Ni:0.1％～0.5％；
the balance being Sn.
In some embodiments, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
Sb:0.8％～1.5％；
Ni:0.1％～0.5％；
the balance being Sn.
In some embodiments, the tin solder comprises the following element contents in percentage by mass:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
Cu:0.8％～1.5％
Ag:0.1％～0.4％
Ni:0.1％；
the balance being Sn.
A second aspect of the present application to achieve the above technical effects is to provide a method for preparing a low-temperature tin solder according to the first aspect, where the method includes: and mixing and melting corresponding raw materials according to the content of each element, casting to form an ingot blank, and converting the ingot blank into any one of paste, tape, foil, sheet, wire, powder or ball.
In some embodiments, the preparation method comprises the following preparation steps:
1) And (3) batching: and respectively configuring each metal raw material according to the mass percentage, specifically, comprising a Sn metal simple substance, a Bi metal simple substance, a Ga metal simple substance, and intermediate alloys formed by alloying elements and elements Sn, wherein the intermediate alloys comprise Sn-Sb, sn-Cu, sn-Ag, sn-Ni, sn-Zn, sn-RE and the like. The purity of the Sn metal simple substance, the Bi metal simple substance and the Ga metal simple substance is preferably 99.99wt.%;
2) Smelting: uniformly mixing the metal raw materials in the step 1), melting, covering an anti-oxidation solvent on the surface of the melted alloy, uniformly mixing, and preserving heat to obtain an alloy melt; the oxidation-resistant solvent is preferably rosin; the smelting is preferably performed in a vacuum environment;
3) And (3) processing and forming: and pouring the alloy melt into a mould to prepare an ingot blank.
In some embodiments, the vacuum environment is a vacuum melting device, the vacuum melting device includes a vacuum melting furnace, and any model of the vacuum melting furnace meets the requirements of the application, which is not described herein.
In some embodiments, inert gas is introduced into the vacuum melting apparatus after the vacuum treatment is completed.
Illustratively, the vacuum melting equipment is filled with inert gas for expelling oxygen-containing gas in the vacuum melting equipment.
In some embodiments, the mixing means comprises stirring, including mechanical stirring and/or electromagnetic stirring.
In some embodiments, the converting comprises using milling equipment and processes, shredding equipment and processes, tabletting equipment and processes, and the like, as is conventional in the art.
Illustratively, the pulverizing apparatus and process comprise centrifugal atomizing pulverizing apparatus and processes conventional in the art.
Illustratively, the wire-making apparatus and process comprise wire-drawing apparatus and processes conventional in the art.
Illustratively, the tableting equipment and process includes soldering lug preparation processes and equipment conventional in the art.
A third aspect of the present application to achieve the above technical effects is to provide a copper-based soldering assembly, where the soldering assembly includes a copper substrate and a solder layer located on a surface of the copper substrate, and the solder layer is obtained by soldering the low-temperature solder according to the first aspect or the low-temperature solder prepared by the method according to the second aspect.
In some embodiments, a portion of the elemental Ga in the tin solder forms a Cu-Ga barrier layer, with the remainder of the elemental Ga forming a Ga-rich phase and being distributed in the Sn matrix in a network or precipitated at Sn phase boundaries.
In some embodiments, the Cu-Ga barrier layer has a thickness of 0.5 μm to 3.0 μm.
Wherein the thickness of the Cu-Ga barrier layer is affected by the Ga content and the aging time, the thickness of the Cu-Ga barrier layer is preferably 0.7 μm to 2.5 μm according to the following examples.
The Cu-Ga barrier layer may have a thickness of 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, or any value satisfying any of the above ranges.
A fourth aspect of the present application to achieve the foregoing technical effects provides a method for manufacturing a component according to the third aspect, including:
the low-temperature tin solder is heated and melted to form molten liquid;
the copper substrate contacts the molten liquid to obtain a tin welding layer;
the temperature of the heated melting is 130-155 ℃.
The fifth aspect of the present application for achieving the technical effects described above provides an application of the low-temperature tin solder prepared by the method described in the first aspect or the low-temperature tin solder prepared by the method described in the second aspect or the copper-based soldering component prepared by the method described in the third aspect or the copper-based soldering component prepared by the method described in the fourth aspect in microelectronic packaging.
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to 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 disclosure to those skilled in the art.
Example 1
Discloses a SnBi58Ga0.1 soldering tin material, which comprises the following preparation methods: adding 99.99wt.% Sn metal and 99.99wt.% Bi metal into a graphite crucible according to mass percent, heating the metals to be completely melted, adding 99.99% Ga metal, covering a layer of rosin on the surface of the molten liquid to prevent oxidation, heating the alloy molten liquid to 400 ℃, preserving heat for 60min, stirring once every 15min to fully and uniformly mix the molten liquid, pouring the molten metal into a mould to prepare an alloy ingot, and air-cooling to room temperature to obtain the SnBi58Ga0.1 alloy ingot.
Example 2
A SnBi45Ga0.5 solder is disclosed, which remains the same as example 1 except for the content of each element.
Example 3
A SnBi40Ga1 solder is disclosed, which remains the same as in example 1 except for the content of each element.
Example 4
A SnBi50Ga2 solder paste is disclosed, which remains the same as in example 1 except for the content of each element.
Example 5
Discloses a SnBi50Ga0.5Sb1 solder, which is prepared by the following steps:
(1) Adding 99.99% Sn metal and 99.99% Sb metal into an intermediate frequency induction smelting furnace according to the mass percentage of 90:10, and vacuumizing to 5×10 -3 And (3) heating to 750 ℃ after filling protective gas under MPa, preserving heat for 60min, uniformly mixing the molten liquid by utilizing electromagnetic stirring, and finally performing vacuum casting, and cooling the alloy ingot to the temperature to obtain the SnSb10 intermediate alloy.
(2) Adding 99.99% Sn metal, 99.99% Bi metal and SnSb10 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% Ga metal after the metal is completely melted, covering a layer of rosin on the surface of the molten liquid, preserving heat for 60min, and stirring every 15 min. And finally, casting the melt into a die, and air-cooling to room temperature to obtain the SnBi50Ga0.5Sb1 alloy ingot.
Tin solder materials such as SnBi50Ga0.5Sb0.1, snBi50Ga0.5Sb0.5 and the like can be prepared by adjusting the content of each metal, and the same technical effects as in the embodiment 5 can be achieved.
Example 6
Discloses a SnBi58Ga0.5Cu1 solder, which is prepared by the following steps:
(1) Adding 99.99% Sn metal and 99.99% Cu metal into an intermediate frequency induction smelting furnace according to the mass percentage of 90:10, and vacuumizing to 5×10 -3 And (3) heating to 1100 ℃ after filling protective gas under MPa, preserving heat for 60min, uniformly mixing the melt by electromagnetic stirring, and finally performing vacuum casting, and cooling the alloy ingot to room temperature to obtain the SnCu10 intermediate alloy.
(2) Step (2) is the same as step (2) in example 5 except that the alloy ratio and the kind of intermediate alloy are different.
Tin solder materials such as SnBi58Ga0.5Cu0.1, snBi58Ga0.5Cu0.5 and the like can be prepared by adjusting the content of each metal, and the same technical effects as in the embodiment 6 can be achieved.
Example 7
Discloses a SnBi58Ga1In1 soldering tin material, and the preparation method of the soldering tin material comprises the following steps: adding 99.99wt.% Sn metal, 99.99wt.% Bi metal and 99.99wt.% In metal into a graphite crucible according to mass percent, heating the metals to be completely melted, adding 99.99% Ga metal, covering a layer of rosin on the surface of the molten liquid to prevent oxidization, heating the alloy molten liquid to 400 ℃, preserving heat for 60min, stirring once every 15min to fully and uniformly mix the molten liquid, pouring the molten metal into a mould to prepare an alloy ingot, and air-cooling to room temperature to obtain the SnBi58Ga1In1 alloy ingot.
Example 8
Discloses a SnBi58Ga1Ag1 soldering tin material, which is prepared by the following steps:
(1) Adding 99.99% Sn metal and 99.99% Ag metal into an intermediate frequency induction smelting furnace according to the mass percentage of 90:10, and vacuumizing to 5×10 -3 And (3) heating to 1100 ℃ after filling protective gas under MPa, preserving heat for 60min, uniformly mixing the melt by electromagnetic stirring, and finally performing vacuum casting, and cooling the alloy ingot to room temperature to obtain the SnAg10 intermediate alloy.
(2) Adding 99.99% Sn metal, 99.99% Bi metal and SnAg10 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% Ga metal after the metal is completely melted, covering a layer of rosin on the surface of the molten liquid, preserving heat for 60min, and stirring every 15 min. And finally, casting the melt into a mould, and air-cooling to room temperature to obtain the SnBi58Ga1Ag1 alloy ingot.
Example 9
Discloses a SnBi58Ga1Ni1 soldering tin material, which is prepared by the following steps:
(1) Adding 99.99% Sn metal and 99.99% Ni metal into an intermediate frequency induction smelting furnace according to the mass percentage of 95:5, and vacuumizing to 5×10 -3 And (3) heating to 1100 ℃ after filling protective gas under MPa, preserving heat for 60min, uniformly mixing the melt by electromagnetic stirring, and finally performing vacuum casting, and cooling the alloy ingot to room temperature to obtain the SnNi5 intermediate alloy.
(2) Adding 99.99% Sn metal, 99.99% Bi metal and SnNi5 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% Ga metal after the metal is completely melted, covering a layer of rosin on the surface of the molten liquid, preserving heat for 60min, and stirring every 15 min. And finally, casting the melt into a mould, and air-cooling to room temperature to obtain the SnBi58Ga1Ni1 alloy ingot.
Example 10
Discloses a SnBi58Ga1In0.5Ag0.5 solder, and the preparation method of the solder comprises the following steps:
(1) The SnAg10 master alloy was prepared in the same manner as in step (1) of example 8;
(2) Adding 99.99% Sn metal, 99.99% Bi metal, 99.99% In metal and SnAg10 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% Ga metal after the metal is completely melted, covering a layer of rosin on the surface of the molten liquid, preserving heat for 60min, and stirring every 15 min. And finally, casting the melt in a die, and air-cooling to room temperature to obtain the SnBi58Ga1In0.5Ag0.5 alloy ingot.
Solder materials such as SnBi58Ga1In0.1Ag0.5, snBi58Ga1In0.8Ag0.5, snBi58Ga1In0.1Ag0.1, and SnBi58Ga1In0.1Ag0.8 can be prepared by adjusting the content of each metal, and the same technical effects as those of example 10 can be achieved.
Example 11
Discloses a SnBi58Ga1Cu1Ni0.1 solder, and the preparation method of the solder comprises the following steps:
(1) The preparation method of the SnCu10 intermediate alloy is the same as that of the step (1) in the example 6;
(2) The preparation method of the SnNi5 intermediate alloy is the same as that of the step (1) in the example 9;
(3) Adding 99.99% of Sn metal, 99.99% of Bi metal, snCu10 intermediate alloy and SnNi5 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% of Ga metal after the metal is completely melted, covering a layer of rosin on the surface of molten liquid, preserving heat for 60min, and stirring every 15 min. And finally, casting the melt into a die, and air-cooling to room temperature to obtain the SnBi58Ga1Cu1Ni0.1 alloy ingot.
The solder materials such as SnBi58Ga0.5Cu0.8Ni0.1, snBi58Ga0.5Cu1.5Ni0.1, snBi58Ga0.5Cu1Ni0.5 and the like can be prepared by adjusting the content of each metal, and the same technical effects as those of the embodiment 11 can be achieved.
Example 12
Discloses a SnBi58Ga0.5Sb1Ni0.1 solder, which is prepared by the following steps:
(1) The preparation method of the SnSb10 intermediate alloy is the same as that of the step (1) in example 5
(2) The preparation method of the SnNi5 intermediate alloy is the same as that of the step (1) in example 9
(3) Adding 99.99% of Sn metal, 99.99% of Bi metal, snSb10 intermediate alloy and SnNi5 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% of Ga metal after the metal is completely melted, covering a layer of rosin on the surface of molten liquid, preserving heat for 60min, and stirring every 15 min. Finally, casting the melt into a die, and air-cooling to room temperature to obtain SnBi58Ga0.5Sb1Ni0.1 alloy ingots.
Solder materials such as SnBi58Ga0.5Sb0.8Ni0.1, snBi58Ga0.5Sb1.5Ni0.1, snBi58Ga0.5Sb0.8Ni0.5 and the like can be prepared by adjusting the content of each metal, and the same technical effects as those of the embodiment 12 can be achieved.
Example 13
Discloses a SnBi58Ga0.5Cu1.5Ag0.4Ni0.1 solder, the preparation method of the solder comprises the following steps:
(1) The preparation method of the SnCu10 intermediate alloy is the same as that of the step (1) of the example 6
(2) The preparation method of the SnAg10 intermediate alloy is the same as that of the step (1) of the example 8
(3) The preparation method of the SnNi5 intermediate alloy is the same as that of the step (1) of the example 9
(4) Adding 99.99% of Sn metal, 99.99% of Bi metal, snCu10 intermediate alloy, snAg10 intermediate alloy and SnNi5 intermediate alloy into a graphite crucible, heating to 400 ℃, adding 99.99% of Ga metal after the metal is completely melted, covering a layer of rosin on the surface of the molten liquid, preserving heat for 60min, and stirring every 15 min. And finally, casting the melt into a die, and air-cooling to room temperature to obtain the SnBi58Ga0.5Cu1.5Ag0.4Ni0.1 alloy ingot.
Comparative example 1
Discloses a SnBi58 soldering tin material, which is prepared by the following steps:
adding 99.99wt.% Sn metal and 99.99wt.% Bi metal into a graphite crucible according to the mass percentage ratio of 42:58, covering a layer of rosin on the surface of the molten liquid to prevent oxidation, heating the alloy molten liquid to 400 ℃, preserving heat for 60min, stirring every 15min to fully and uniformly mix the molten liquid, pouring the molten metal into a mould to prepare an alloy ingot, and air-cooling to room temperature to obtain the SnBi58 alloy ingot.
The application also discloses that the alloy ingots prepared in the above examples and comparative examples are converted into any one of paste, tape, foil, sheet, wire, powder or ball, and the application is not repeated because the related art is involved.
Test:
(1) Melting point testing of the alloy is completed by using a conventional differential thermal analyzer, wherein the heating rate is set to 10 ℃/min, and an intersection point of a front baseline extension line and a tangent line at the maximum slope of the front edge of a peak is taken as the melting point of the alloy. A list of melting points shown in table 1 was obtained.
(2) The alloy solders prepared in the examples and the comparative examples are used for welding copper substrates to obtain copper-based welding assemblies, and specifically, the alloy solders are heated and melted at 135-155 ℃ to form molten liquid; contacting the copper substrate with the melt to obtain a tin welding layer; the soldering layer comprises a soldering interface; the method further comprises the step of carrying out aging treatment on the welding interface for 100 ℃ multiplied by 480 hours, wherein the aging treatment is continuous aging treatment for 100 ℃ multiplied by 480 hours;
microstructure organization of the copper-based welding assembly and the welding interface is as follows;
(3) Microstructure tissue observation and micro-region element distribution are analyzed by using an electronic probe device. The adopted analysis equipment is equipment of a conventional model in the field, and the analysis method meets the corresponding national standard.
Table 2 and FIGS. 1 to 6 were obtained.
Table 1 list of each solder alloy composition and melting point in examples and comparative examples
| Examples | Solder alloy composition | Alloy melting point (. Degree. C.) |
| Example 1 | SnBi58Ga0.1 | 137.81 |
| Example 2 | SnBi45Ga0.5 | 143.68 |
| Example 3 | SnBi40Ga1 | 142.72 |
| Example 4 | SnBi50Ga2 | 139.22 |
| Example 5 | SnBi50Ga0.5Sb1 | 140.34 |
| Example 6 | SnBi58Ga0.5Cu1 | 139.27 |
| Example 7 | SnBi58Ga1In1 | 137.11 |
| Example 8 | SnBi58Ga1Ag1 | 137.42 |
| Example 9 | SnBi58Ga1Ni1 | 137.51 |
| Example 10 | SnBi58Ga1In0.5Ag0.5 | 137.33 |
| Example 11 | SnBi58Ga1Cu1Ni0.1 | 140.27 |
| Example 12 | SnBi58Ga0.5Sb1Ni0.1 | 139.46 |
| Example 13 | SnBi58Ga0.5Cu1.5Ag0.4Ni0.1 | 139.12 |
| Comparative example 1 | SnBi58 | 138.24 |
Table 2 characterization and performance of the solder interface of each solder alloy in examples and comparative examples
Fig. 1 and 2 show the microstructure and element distribution diagrams of the soldering interface between the tin solder of example 1 and the Cu substrate of example 4, respectively, and as can be seen from fig. 1 and 2, a continuous Cu-Ga intermetallic compound layer is formed at the soldering interface, the Cu-Ga barrier layer composed of the Cu-Ga intermetallic compound layer has a thickness of 0.5 μm to 3.0 μm, no formation of Cu-Sn intermetallic compound is observed, and no Bi-rich layer is formed in the vicinity of the soldering interface, which indicates that the dense Cu-Ga intermetallic compound effectively inhibits diffusion of Cu and Sn elements, acts as a diffusion barrier layer, and effectively inhibits formation of Bi-rich layer. Fig. 3 is a microstructure and element distribution diagram of the soldering interface between the solder of comparative example 1 and the Cu substrate, and it is understood from fig. 3 that cu—sn intermetallic compound remains at the soldering interface.
Fig. 4 is a microstructure and an element distribution diagram of the welded interface of example 1 after aging treatment, and, as shown in fig. 4, the welded interface is still a Cu-Ga compound layer and is not significantly grown after long-time aging treatment, and no Cu-Sn compound layer is formed, which indicates that the Cu-Ga barrier layer can still effectively inhibit interdiffusion of Cu and Sn elements, reduce the growth rate of intermetallic compounds, and inhibit formation of Cu-Sn intermetallic compounds and Bi-rich layers during aging.
Fig. 5 is a microstructure and element distribution diagram of the welded interface of comparative example 1 after aging treatment, and it can be seen from fig. 5 that the cu—sn compound layer thickness is significantly increased and a significant scallop structure is exhibited.
Fig. 6 shows a microstructure of example 4, and in combination with fig. 6, it can be seen that Ga element in the alloy is precipitated in the form of Ga-rich phase in Sn phase grains and at grain boundaries, which plays a role in refining grains, is beneficial to improving strength and toughness of the solder, and prevents grains from growing during aging, further reduces growth rate of intermetallic compounds, and improves reliability of the solder.
In conclusion, the tin solder provided by the application has the advantages of uncomplicated self components, simple preparation process, suitability for welding copper plates, good wettability of a welding interface, proper interface strength, high reliability of welding spots and long service life. It is suitable for the field of microelectronic packaging.
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 "having" 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 described or illustrated, unless an order of performance is explicitly stated. It should also be appreciated that additional or alternative steps may be used.
The foregoing is merely a preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present application should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A low temperature tin solder for copper substrates, characterized in that the tin solder comprises the following element contents in mass percent:
Bi:40.0％～58.0％；
Ga:0.1％～2.0％；
the balance being Sn.
2. The low temperature tin solder according to claim 1, wherein the tin solder comprises the following element contents in mass percent:
Bi:45.0％～58.0％；
Ga:0.5％～2.0％；
the balance being Sn.
3. The low temperature tin solder according to claim 1 or 2, further comprising alloying elements in an amount by mass that satisfies:
alloying elements are more than 0 and less than or equal to 2.0 percent;
and the alloying element comprises one or two or more of Sb, cu, in, ag, ni, zn, a misch metal comprising a lanthanum-cerium alloy.
4. The low temperature tin solder according to claim 3, wherein the tin solder comprises the following element contents in mass percent:
Bi:45.0％～58.0％；
Ga:0.5％～1.5％；
0.1 to 1.5 percent of alloying element; the alloying element comprises one or two or more of Sb, cu, in, ag, ni, zn;
the balance of Sn;
and the eutectic melting point of the tin solder is 130-150 ℃.
5. A method of producing the low-temperature tin solder according to any one of claims 1 to 4, comprising: and mixing and melting corresponding raw materials according to the content of each element, casting to form an ingot blank, and converting the ingot blank into any one of paste, tape, foil, sheet, wire, powder or ball.
6. A copper-based solder assembly, characterized in that the solder assembly comprises a copper substrate and a solder layer on the surface of the copper substrate, the solder layer being soldered by the low temperature solder according to any one of claims 1 to 4 or the low temperature solder prepared by the method according to claim 5.
7. The copper-based solder assembly according to claim 6, wherein a part of the element Ga in the tin solder forms a Cu-Ga barrier layer, and the remaining element Ga forms a Ga-rich phase and is distributed in a mesh form in the Sn matrix or precipitates at Sn phase grain boundaries.
8. Copper-based welded assembly according to claim 6 or 7, characterized in that the Cu-Ga barrier layer has a thickness of 0.5 μm to 3.0 μm, preferably 0.7 μm to 2.5 μm.
9. A method of making an assembly according to any one of claims 6 to 7, comprising:
the low-temperature tin solder is heated and melted to form molten liquid;
and the copper substrate is contacted with the molten liquid to obtain a tin welding layer.
10. Use of a low temperature tin solder according to any one of claims 1 to 4 or a low temperature tin solder prepared by a method according to claim 5 or a copper-based soldered component according to any one of claims 6 to 8 or a copper-based soldered component prepared by a method according to claim 9 in microelectronic packaging.
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