CN117840629A - Low-melting-point In-Bi-Sn-Ag alloy solder, and preparation method and application thereof - Google Patents
Low-melting-point In-Bi-Sn-Ag alloy solder, and preparation method and application thereof Download PDFInfo
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- CN117840629A CN117840629A CN202410031970.1A CN202410031970A CN117840629A CN 117840629 A CN117840629 A CN 117840629A CN 202410031970 A CN202410031970 A CN 202410031970A CN 117840629 A CN117840629 A CN 117840629A
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- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 111
- 239000000956 alloy Substances 0.000 title claims abstract description 111
- 229910000679 solder Inorganic materials 0.000 title claims abstract description 93
- 229910020836 Sn-Ag Inorganic materials 0.000 title claims abstract description 45
- 229910020988 Sn—Ag Inorganic materials 0.000 title claims abstract description 45
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- 238000002844 melting Methods 0.000 claims abstract description 27
- 230000008018 melting Effects 0.000 claims abstract description 27
- 229910052738 indium Inorganic materials 0.000 claims abstract description 20
- 229910052718 tin Inorganic materials 0.000 claims abstract description 16
- 229910052709 silver Inorganic materials 0.000 claims abstract description 15
- 229910052797 bismuth Inorganic materials 0.000 claims abstract description 10
- 229910052751 metal Inorganic materials 0.000 claims description 29
- 239000002184 metal Substances 0.000 claims description 29
- 239000010453 quartz Substances 0.000 claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- 239000000945 filler Substances 0.000 claims description 21
- 239000002994 raw material Substances 0.000 claims description 10
- 238000007789 sealing Methods 0.000 claims description 10
- 238000003723 Smelting Methods 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 6
- 238000004321 preservation Methods 0.000 claims description 6
- 238000004100 electronic packaging Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 5
- 239000000758 substrate Substances 0.000 abstract description 20
- 229910020830 Sn-Bi Inorganic materials 0.000 abstract description 14
- 229910018728 Sn—Bi Inorganic materials 0.000 abstract description 14
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- 238000012360 testing method Methods 0.000 description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- 230000008569 process Effects 0.000 description 8
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- 238000005476 soldering Methods 0.000 description 7
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
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- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 2
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Abstract
The invention discloses a low-melting-point In-Bi-Sn-Ag alloy solder, and a preparation method and application thereof, wherein the In-Bi-Sn-Ag alloy solder comprises the following components In percentage by mass: 15-25% of Sn, 10-30% of In, 1-12% of Ag and 40-60% of Bi; the atomic percentage of the sum of In and Ag and the atomic percentage of Bi and Sn is 35.7:39.3:25. based on a theoretical model of "(cluster) connecting atoms", and combining phase diagram, mixing enthalpy and strong interaction principle, the composite addition of Ag element and In element is combined on the basis of Sn-Bi, and the component proportion of each alloy element is strictly controlled, so that the method has the advantages of low melting point, good wettability of Cu and Ni substrates, high welding strength, moderate cost, no lead, more environmental protection and the like, is particularly suitable for flexible substrate interconnection, and can also be applied to 3D IC multilayer packaging.
Description
Technical Field
The invention relates to the technical field of alloy solders, in particular to a low-melting-point In-Bi-Sn-Ag alloy solder, and a preparation method and application thereof.
Background
Lead-tin solder plays an important role in the electronics industry and is widely used in the field of electronic packaging due to its excellent solderability and service properties. However, since lead is a great hazard to human health and living environment, disabling lead has become a consensus of all humans, and related measures have been taken internationally to prohibit the use of lead. In order to replace lead-tin solders, researchers have developed lead-free solders. With the development of high integration, high performance and multifunction of electronic products, warpage easily occurs when the current lead-free solder is used for packaging the electronic products, and defects of pillow, bridging and non-wetting are generated. It is found that the above problems can be well solved by lowering the soldering temperature, and therefore, the low-temperature soldering with the low-temperature solder becomes a direction to solve the problems, and therefore, the low-temperature lead-free alloy solder for flexible substrate interconnection is successfully designed and developed, and has a very wide application prospect.
At present, sn-Bi-based alloy (eutectic component Sn-58 Bi) is widely applied, but the melting point of solder of the Sn-Bi-based alloy is still too high for flexible substrate interconnection, the brazing process temperature is up to 170-200 ℃, and the Sn-Bi-based alloy has larger brittleness and lower toughness and is not suitable for the current flexible substrate interconnection. In order to solve the problems of high melting point, high cost, insufficient mechanical property and the like of binary alloy, sn-Bi-In ternary alloy becomes a flexible substrate interconnection solder alternative with great competitiveness, and the research on the interfacial microstructure and mechanical property of 22.15Sn-18.75Bi-59.1Inat% near ternary eutectic alloy solder of university of continuous engineering, M.L. Huang and the like is carried out, so that the tensile property, the elongation and the wettability on a Cu substrate of the bulk solder are researched. E.E.M.Noor et al studied the wettability and microstructure of the 19.6Sn-31.6Bi-48.8Inwt% ternary eutectic (melting point 61.33 ℃ C.), calculated the surface tension and contact angle of Sn-Bi-In solder at different reflow temperatures on Cu substrates, studied the characteristics of interfacial intermetallic compounds (Intermetallic Compounds, IMC) and Cu/solder/Cu joint shear strength. However, the low-melting-point phase InBi (melting point 110 ℃) In the Sn-Bi-In ternary alloy causes the defects of insufficient welding spot strength, low reliability, smaller service temperature range and the like of the solder after welding, and the alloy solder has higher cost due to higher general content of In element In the alloy at present, so that the large-scale application of the alloy is limited, and therefore, the proper addition of a fourth component In the alloy for improving the strength of the solder and the soldered joint is the focus of attention of researchers at present.
Currently, for Sn-Bi-In-X patents, there are mainly: the patent CN113084391A discloses a low-melting-point green flexible 3D alloy, which is prepared by adopting an alloying mode, and comprises 88Sn- (10-x) In-2Zn-xBi, wherein x is more than or equal to 1 and less than or equal to 5, the melting point is between 162.5 ℃ and 179 ℃, and the temperature is too high for the interconnection and gradient welding of the existing flexible substrate; the preparation method of the aluminum alloy low-temperature brazing solder disclosed in the patent CN103231180A comprises the following components in percentage by mass: 25-29% of tin, 12-17% of gallium, 22-26% of indium and the balance of bismuth, wherein low-melting-point liquid gallium exists in an alloy system, so that the requirements of commercial environmental test cannot be met; the solder alloy and the solder disclosed in the patent CN108941968A comprise the following components in percentage by mass: 18 to 28 percent of indium, 44.5 to 54.5 percent of bismuth, 0.01 to 1.45 percent of zirconium and the balance of tin, and a large amount of IMC phases and continuous Bi-rich phases generated in welding spots have insufficient plasticity to meet the interconnection requirement of flexible substrates.
Disclosure of Invention
The invention aims to overcome the defects In the prior art and provide the low-melting-point In-Bi-Sn-Ag alloy solder with the advantages of low melting point, good wettability of Cu and Ni substrates, high welding strength, moderate cost, no lead, more environmental protection and the like, and the preparation method and the application thereof.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
the low-melting-point In-Bi-Sn-Ag alloy brazing filler metal comprises the following components In percentage by mass: 15-25% of Sn, 10-30% of In, 1-12% of Ag and 40-60% of Bi; the atomic percentage of the sum of the atomic percentages of In and Ag and the atomic percentage of Bi and Sn is 35.7:39.3:25.
the invention also discloses a preparation method of the low-melting-point In-Bi-Sn-Ag alloy solder, which comprises the following steps:
filling Sn, in, bi and Ag into a quartz tube for vacuum tube sealing;
after tube sealing is finished, the quartz tube is put into a resistance furnace for smelting;
and (3) after the Sn, the In, the Bi and the Ag raw materials are completely melted, carrying out heat preservation, taking out the quartz tube, and cooling to room temperature to obtain the In-Bi-Sn-Ag alloy solder.
The invention also discloses application of the low-melting-point In-Bi-Sn-Ag alloy solder or the low-melting-point In-Bi-Sn-Ag alloy solder prepared by the preparation method In the field of electronic packaging.
The implementation of the embodiment of the invention has the following beneficial effects:
aiming at the characteristics of Sn-Bi alloy solder, the embodiment of the invention is based on a theoretical model of "(cluster) connecting atoms, combines phase diagram, mixing enthalpy and strong interaction principle, combines the composite addition of Ag element and In element on the basis of Sn-Bi base solder, and strictly controls the component proportion of each alloy element, wherein the embodiment of the invention controls the added In element and Sn-Bi base solder to be In a specific proportion range, and the addition of In element ensures that eutectic alloy generates Cu after reflow 6 (Sn,In) 5 Intermetallic compound phase, improving alloy wettability and interface binding force, and can reduce melting point of alloy solder and effectively control cost of solder; the addition of Ag element can further optimize the components of the In-Bi-Sn based solder, the mixing enthalpy (-1 kJ/mol) of In and Bi is higher than that (-2 kJ/mol), and during solidification, phases with lower mixing enthalpy tend to be generated by reducingThe content of low-melting-point phase InBi is low, the ratio of gamma-Sn phase to Bi-rich phase is improved, the generation of low-temperature phase InBi after reflow is reduced, and Ag with higher melting point and better mechanical property is generated in welding spots formed by brazing 2 In, the strength of the alloy is 91.2MPa, the alloy strength can be improved on the premise of not influencing the melting process, the growth of an interface IMC is inhibited, the reliability of a braze joint is improved, the service temperature range is improved, the wetting capability is ensured, the effect of refining grains is achieved, the effect of inhibiting the growth of the grains is achieved, and the distribution of each phase is more uniform.
In summary, the In-Bi-Sn-Ag alloy solder In the embodiment of the invention carries out component adjustment on the basis of Sn-Bi solder, adds Ag element and In element for compounding, reduces the addition amount of the In element, brings space for adding the Ag element, obviously improves the comprehensive performance, especially the reliability, of the alloy through the synergistic effect of the In element, bi element, sn element and Ag element, controls the liquidus temperature between 80 ℃ and 105 ℃, can braze at a low brazing process temperature between 110 ℃ and 130 ℃, avoids the warping problem caused by high temperature In the traditional reflow process, has the advantages of low melting point, good wettability of Cu and Ni substrates, high welding strength, moderate cost, no lead, more environmental protection and the like, is particularly suitable for flexible substrate interconnection, and can also be applied to 3D IC multilayer packaging.
Drawings
FIG. 1 is a microstructure view of a bulk filler metal of example 1 and comparative example 1 of the present invention.
FIG. 2 is a microstructure view of the solder/Cu interface of example 1 and comparative example 1 of the present invention.
Fig. 3 is a schematic illustration of the lap joint construction of the braze joint of the present invention.
Fig. 4 is a schematic view of a shear test of a braze joint of the present invention.
Detailed Description
The invention is further illustrated below in connection with specific examples, but is not limited in any way.
The present inventors have conducted intensive studies on a Sn-Bi alloy solder In a lead-free alloy solder, and first examined the alloy composition so as to lower the liquidus temperature, and the present inventors have found that In is added to a Sn-Bi alloy solder: the melting point of the Sn-52In eutectic solder is 118 ℃, the difference between the Sn-52In eutectic solder and the Sn-Bi eutectic alloy is not large, the problem of relatively high melting point exists, the In-Bi alloy has three eutectic points, namely, the In-67Bi eutectic alloy (110 ℃), the In-50Bi (88 ℃ C.) and the In-32Bi (72 ℃ C.), meanwhile, the defects of insufficient welding spot strength, low reliability, small service temperature range and the like caused by the appearance of low-melting-point phase InBi after the solder is welded are found, and the common content of the added In the prior art is high, so that the cost of the alloy solder is high.
Accordingly, the inventors have studied the contents of the respective constituent elements in further detail while taking the balance of the whole into consideration and adding the fourth component to the alloy filler metal system.
The present invention obtained from these findings is as follows.
The invention discloses a low-melting-point In-Bi-Sn-Ag alloy solder, which comprises the following components In percentage by mass: 15 to 25 percent of Sn, 10 to 30 percent of In, 1 to 12 percent of Ag and 40 to 60 percent of Bi.
The principle of the invention is as follows: the Sn-Bi alloy solder is selected as a matrix, based on a theoretical model of "(cluster) connecting atoms", and combined with a phase diagram, mixing enthalpy and a strong interaction principle, the composite addition of Ag and In is combined on the basis of the Sn-Bi alloy solder, and the proportion of each alloy element component is strictly controlled, so that the obtained In-Bi-Sn-Ag alloy solder has the advantages of low melting point, good wettability of Cu and Ni substrates, high welding strength, moderate cost, no lead, more environmental protection and the like.
Specifically, when Sn and Bi are added to the lead-free alloy solder in the above range, bi is solid-dissolved in the Sn matrix, and the lead-free alloy solder can be further strengthened, but when the Sn content is too high, an excessively thick interface IMC is generated, the joint reliability is lowered, and when the Sn content is too low, the above effects cannot be exerted; when the content of Bi is too low, the above effect cannot be exhibited, and when the content of Bi is too high, solidification segregation becomes remarkable in the solid-liquid coexisting region, and the occurrence frequency of warpage becomes high.
Further, the method comprisesBased on the above, the inventors have determined that the alloy solder has excellent properties by a large number of component optimization experiments: the atomic percentage of the sum of In and Ag and the atomic percentage of Bi and Sn is 35.7:39.3:25, controlling the added In and Sn-Bi base solder to be In a specific proportion range, namely under the synergistic effect of In, bi and Sn, enabling the eutectic alloy to generate Cu after reflow 6 (Sn,In) 5 Intermetallic compound phase, improves the wettability and interfacial binding force of the alloy, can reduce the melting point of the alloy solder and effectively control the cost of the solder. Further, based on the above, in order to further enhance the joining strength of the soldered joint, the inventors have further optimized the composition of the alloy solder by a large number of composition optimization experiments, and determined the composition ratio of the alloy solder having excellent properties: the atomic percentage of In and Ag is 35.7%, because the mixing enthalpy (-1 kJ/mol) of In and Bi is higher than that of In and Ag (-2 kJ/mol), phases with lower mixing enthalpy tend to be generated In the solidification process, the ratio of gamma-Sn phase and Bi-rich phase is improved by reducing the content of low-melting-point phase InBi, the generation of low-temperature phase InBi after reflow is reduced, and Ag with higher melting point and better mechanical property is generated In a welding spot formed by brazing is introduced 2 In, the strength of the alloy is 91.2MPa, the alloy strength can be improved on the premise of not influencing the melting process, the growth of an interface IMC is inhibited, the reliability of a braze joint is improved, the service temperature range is improved, the wetting capability is ensured, the effect of refining grains is achieved, the effect of inhibiting the growth of the grains is achieved, and the distribution of each phase is more uniform. However, when the Ag content is too high, large pieces of Ag may be formed after reflow 3 Sn causes insufficient strength of welding spots, and when the content of Ag is too small, the effect of inhibiting the growth of interface IMC is insufficient, and the strength of the welding spots is not good.
In a specific embodiment, the inventors focused on first, in order to suppress the occurrence of warpage, since the alloy is a material In which all constituent elements are combined into one body, the constituent elements affect each other, and the In content is adjusted to a prescribed range by achieving balance of Sn, bi and In content, and the total amount of Ag content and In content is defined on the basis of this, whereby the alloy solder of the embodiment of the present invention can have a liquidus temperature of 80 to 105 ℃ with good mechanical strength; the solidus temperature of the In-Bi-Sn-Ag alloy solder is 80-85 ℃, and the soldering can be performed by adopting the low-temperature soldering process temperature of 110-130 ℃, so that the problem of warping caused by high temperature In the traditional reflow process is avoided.
In one embodiment, the mass percentage of Ag is preferably 1% -11%.
In one embodiment, the Bi source material is in the form of Bi blocks having a purity of 99.99%; the In raw material is In the form of In blocks with the purity of 99.99%; the raw material form of Ag is Ag block with the purity of 99.99%; the raw material form of Sn was a Sn mass having a purity of 99.99%.
The invention also discloses a preparation method of the low-melting-point In-Bi-Sn-Ag alloy solder according to any embodiment of the invention, which comprises the following steps:
1) Sn, in, bi and Ag are filled into a quartz tube for vacuum sealing.
2) And after tube sealing is finished, the quartz tube is put into a resistance furnace for smelting.
3) And (3) after the Sn, in, bi and Ag raw materials are completely melted, carrying out heat preservation, taking out the quartz tube, and cooling to room temperature to obtain the In-Bi-Sn-Ag alloy solder.
In a specific embodiment, the preparation method of the low-melting-point In-Bi-Sn-Ag alloy solder specifically comprises the following steps:
(1) The metal Sn with the purity of 99.99%, the metal In with the purity of 99.99%, the metal Bi with the purity of 99.99% and the metal Ag with the purity of 99.99% are weighed 100g according to the proportion of any embodiment of the invention, and placed into a quartz tube.
(2) Sealing one end of quartz tube by hydrogen flame, sealing the other end, vacuum pumping to make the vacuum degree in tube 1×10 -3 Pa～1×10 -4 Pa, after the air in the pipe is exhausted, the thin opening is burnt, melted and sealed.
(3) And (3) placing the quartz tube in the step (2) in a resistance furnace, heating to 700-1000 ℃ for smelting, and preserving heat for 3-4 hours at 700-1000 ℃ after all components are melted, so that the alloy is homogenized, and rotating the quartz tube once every 30 minutes to ensure that the liquid alloy in the quartz tube is more uniform.
(4) And after smelting is completed, taking out the quartz tube, and cooling to room temperature to obtain the low-melting-point In-Bi-Sn-Ag alloy solder.
Specifically, the preparation method can ensure that trace alloy elements are uniformly added into the alloy solder by regulating and controlling the technological parameters such as smelting temperature, smelting time, cooling mode and the like, and can more accurately control the components of the alloy elements to obtain a good microstructure, and finally obtain the low-melting-point In-Bi-Sn-Ag alloy solder with good welding spot combination and high reliability.
The following are specific examples
Example 1
The In-Bi-Sn-Ag alloy solder of the embodiment comprises the following components In percentage by mass: 19.44% of Sn, 53.78% of Bi, 1.26% of Ag and the balance of In.
The liquidus temperature of the In-Bi-Sn-Ag alloy solder of the embodiment is 80-105 ℃; the solidus temperature of the In-Bi-Sn-Ag alloy solder is 80-85 ℃.
The preparation method of the low-melting-point In-Bi-Sn-Ag alloy solder comprises the following steps:
(1) The metal Sn with the purity of 99.99%, the metal In with the purity of 99.99%, the metal Bi with the purity of 99.99% and the metal Ag with the purity of 99.99% are weighed 100g according to the proportion of any embodiment of the invention, and placed into a quartz tube.
(2) Sealing one end of quartz tube by hydrogen flame, sealing the other end, vacuum pumping to make the vacuum degree in tube 1×10 -3 Pa, after the air in the pipe is exhausted, the thin opening is burnt, melted and sealed.
(3) And (3) placing the quartz tube in the step (2) in a resistance furnace, heating to 700-1000 ℃ for smelting, and preserving heat for 3 hours at 700-1000 ℃ after all components are melted, so that the alloy is homogenized, and rotating the quartz tube once every 30min to ensure that the liquid alloy in the quartz tube is more uniform.
(4) And after smelting is completed, taking out the quartz tube, and cooling to room temperature to obtain the low-melting-point In-Bi-Sn-Ag alloy solder.
Example 2
The In-Bi-Sn-Ag alloy solder of the embodiment comprises the following components In percentage by mass: 19.46% of Sn, 53.83% of Bi, 2.52% of Ag and the balance of In.
The preparation method of this example is the same as that of example 1.
Example 3
The In-Bi-Sn-Ag alloy solder of the embodiment comprises the following components In percentage by mass: 19.47% of Sn, 53.87% of Bi, 3.79% of Ag and the balance of In.
The preparation method of this example is the same as that of example 1.
Example 4
The In-Bi-Sn-Ag alloy solder of the embodiment comprises the following components In percentage by mass: 19.49% of Sn, 53.91% of Bi, 5.06% of Ag and the balance of In.
The preparation method of this example is the same as that of example 1.
Example 5
The In-Bi-Sn-Ag alloy solder of the embodiment comprises the following components In percentage by mass: 19.50% of Sn, 53.96% of Bi, 6.33% of Ag and the balance of In.
The preparation method of this example is the same as that of example 1.
Example 6
The In-Bi-Sn-Ag alloy solder of the embodiment comprises the following components In percentage by mass: 19.57% of Sn, 54.13% of Bi, 11.43% of Ag and the balance of In.
The preparation method of this example is the same as that of example 1.
Comparative example 1
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 19.43% of Sn, 53.74% of Bi and the balance of In.
The preparation method of this comparative example was the same as in example 1.
Comparative example 2
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 48% Sn, the balance In
The preparation method of this comparative example was the same as in example 1.
Comparative example 3
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 51.6% of Sn, 47.7% of Bi and the balance of Ag.
The preparation method of this comparative example was the same as in example 1.
Comparative example 4
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: bi 67%, the balance being In.
The preparation method of this comparative example was the same as in example 1.
Comparative example 5
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 42% of Sn and the balance Bi.
The preparation method of this comparative example was the same as in example 1.
Comparative example 6
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 25.53% of Sn, 49.94% of Bi, 2.58% of Ag and the balance of In.
The preparation method of this comparative example was the same as in example 1.
Comparative example 7
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 13.62% of Sn, 57.55% of Bi, 2.48% of Ag and the balance of In
The preparation method of this comparative example was the same as in example 1.
Comparative example 8
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 19.99% of Sn, 55.31% of Bi, 2.60% of Ag and the balance of In.
The preparation method of this comparative example was the same as in example 1.
Comparative example 9
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 18.98% of Sn, 52.49% of Bi, 4.93% of Ag and the balance of In.
The preparation method of this comparative example was the same as in example 1.
Comparative example 10
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 13.29% of Sn, 56.16% of Bi, 4.84% of Ag and the balance of In.
The preparation method of this comparative example is the same as in example 1,
comparative example 11
The alloy brazing filler metal of the comparative example comprises the following components in percentage by mass: 42% of Sn, 50% of Bi and the balance of In.
The preparation method of this comparative example was the same as in example 1.
Test case
1. Metallographic structure diagram test was conducted on example 1 and comparative example 1, and as shown in FIGS. 1 and 2, it was found that Cu was present in the alloy filler metal prepared in example 1 6 (Sn,In) 5 And Ag 2 In。
2. The wettability test and the shear property test of the soldered joint on the copper substrate were performed on the alloy solders of examples 1 to 6 and comparative examples 1 to 11, in which the soldered joint adopts a lap joint type joint, the lap joint structure is shown in fig. 3, and fig. 3 is a schematic diagram of the lap joint structure of the soldered joint of the present invention. The experimental conditions were as follows: (1) The alloy solders of examples 1 to 6 and comparative examples 1 to 11 were made into solder balls having a diameter of 1.5mm, and the solder balls were placed on a copper substrate and a nickel substrate coated with 12mg of a commercially available brazing flux, with a 300 μm spacer placed therebetween to control the pitch. And (3) placing the lapped joint into a reflow oven for heating, and measuring the spreading area of the alloy solder on the copper substrate and the nickel substrate after reflow soldering by using graphic software. (2) After the joints are assembled, the joints are placed into a reflow oven to be heated according to a set reflow curve, the soldered joints are taken out after reflow, then the shearing strength of the soldered joints is tested by a universal tensile testing machine, a shearing strength tensile testing schematic diagram is shown in fig. 4, and fig. 4 is a shearing testing schematic diagram of the soldered joints. (3) Melting point test under the condition that the temperature rising rate is 10 ℃/min, a Differential Scanning Calorimeter (DSC) is used for testing, the mass of a sample is 30mg, the numerical processing is automatically calculated by software, the peak temperature of a DSC curve is recorded as the melting point value of the alloy solder, and the test result is shown in table 1.
TABLE 1 results of Performance test of examples 1-6 and comparative examples 1-11
According to the test results of table 1, examples 1 to 6 have more excellent wetting ability and shearing strength than comparative examples 1 to 11, and it is described that the In-Bi-Sn-Ag alloy solders of examples 1 to 6 are subjected to component adjustment based on Sn-Bi solder, are compounded by adding Ag and In, and through a large number of component optimization experiments, the component proportion of the alloy solders with excellent performance is determined, by reducing the addition amount of In, space is provided for the addition of Ag, and under the conditions that all constituent elements respectively fall into a specified range and meet the specific component proportion, the comprehensive performance, especially reliability, of the alloy is remarkably improved by the synergistic effect of In, bi, sn, ag, the liquidus temperature is controlled to be between 80 ℃ and 105 ℃, and the soldering can be performed by adopting a low-temperature soldering process temperature of 110 ℃ to 130 ℃, so that the warpage problem caused by high temperature In the traditional reflow process is solved, and the alloy solder composition has the advantages of low melting point, good Cu and Ni substrate wetting property, moderate cost, no lead, and the like, and is particularly applicable to multilayer interconnection, and also applicable to 3D IC package.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. The low-melting-point In-Bi-Sn-Ag alloy solder is characterized by comprising the following components In percentage by mass:
15-25% of Sn, 10-30% of In, 1-12% of Ag and 40-60% of Bi;
the atomic percentage of the sum of the atomic percentages of In and Ag and the atomic percentage of Bi and Sn is 35.7:39.3:25.
2. the low melting point In-Bi-Sn-Ag alloy filler metal of claim 1, wherein the mass percent of Ag is 1% to 11%.
3. The low melting point In-Bi-Sn-Ag alloy filler metal of claim 1, wherein the liquidus temperature of the In-Bi-Sn-Ag alloy filler metal is 80 ℃ to 105 ℃;
the solidus temperature of the In-Bi-Sn-Ag alloy solder is 80-85 ℃.
4. The low melting point In-Bi-Sn-Ag alloy filler metal according to claim 1, wherein the raw material form of Bi is Bi blocks having a purity of 99.99%;
the In raw material is In the form of In blocks with the purity of 99.99%;
the raw material form of the Ag is an Ag block with the purity of 99.99%;
the raw material form of Sn is Sn block with the purity of 99.99 percent.
5. A method for producing the low melting point In-Bi-Sn-Ag alloy solder according to any one of claims 1 to 4, comprising the steps of:
filling Sn, in, bi and Ag into a quartz tube for vacuum tube sealing;
after tube sealing is finished, the quartz tube is put into a resistance furnace for smelting;
and (3) after the Sn, the In, the Bi and the Ag raw materials are completely melted, carrying out heat preservation, taking out the quartz tube, and cooling to room temperature to obtain the In-Bi-Sn-Ag alloy solder.
6. The method for producing a low melting point In-Bi-Sn-Ag alloy filler metal according to claim 5, wherein the melting temperature is 700 ℃ to 1000 ℃;
when the vacuum tube is sealedVacuum degree in tube of 1X 10 -3 Pa～1×10 -4 Pa。
7. The method for producing a low melting point In-Bi-Sn-Ag alloy filler metal according to claim 6, wherein the temperature of the heat preservation is 700 ℃ to 1000 ℃;
the heat preservation time is 3-4 hours.
8. The method for producing a low melting point In-Bi-Sn-Ag alloy solder according to claim 7, further comprising: and rotating the quartz tube every 30min during heat preservation.
9. The method for producing a low melting point In-Bi-Sn-Ag alloy solder according to claim 5, wherein the purities of the Sn, in, bi, and Ag are 99.99%.
10. Use of the low-melting-point In-Bi-Sn-Ag alloy solder according to any one of claims 1 to 4 or the low-melting-point In-Bi-Sn-Ag alloy solder prepared by the preparation method according to any one of claims 5 to 9 In the field of electronic packaging.
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