Corrosion-resistant tin-based alloy solder and preparation method thereof

Abstract

The invention discloses corrosion-resistant tin-based alloy solder and a preparation method thereof, and belongs to the technical field of alloy solder. The tin-based alloy solder comprises the following components in percentage by mass: 0.7% of Cu, 0.05%-0.21% of Ni, one of Zn or Al, 0.05%-0.15% of Zn, 0.02%-0.1% of Al and the balance of Sn. The tin-based alloy solder containing strip-shaped Cu6Sn5 intermetallic compounds, needle-shaped (Cu, Ni) 6Sn5 intermetallic compounds, needle-shaped Cu6 (Sn, Zn) 5 intermetallic compounds, needle-shaped Cu6 (Sn, Al) 5 intermetallic compounds and sheet-shaped (Cu, Ni) 6 (Sn, Al) 5 intermetallic compounds is prepared by optimizing the alloy solder formula and combining the preparation method, and the thermodynamic stability and corrosion resistance of the tin-based alloy solder are effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy solders and relates to a corrosion-resistant tin-based alloy solder and a preparation method thereof. Background Art

[0002] Solder is an important industrial raw material for connecting electronic components in welding circuits. It is a solder with a low melting point, mainly referring to solder made of tin-based alloys.

[0003] Sn-0.7Cu lead-free solder is considered to be one of the important development directions of new solders in recent years because of its economic efficiency. The comprehensive performance of solder directly affects whether electronic products can maintain normal use for a long time. Solder corrosion resistance is one of the considerations of solder comprehensive performance, and it is also a key factor in the reliability of electronic products. Therefore, it is of great significance to improve the corrosion resistance of Sn-0.7Cu lead-free solder, extend the service life of electronic products, and improve the reliability of electronic products.

[0004] Therefore, it is necessary to provide a corrosion-resistant tin-based alloy solder and a preparation method thereof, so as to effectively improve the corrosion resistance of the tin-based lead-free solder, thereby enabling electronic products to maintain high long-term reliability. Summary of the invention

[0005] In order to overcome the problems in the background technology, the present invention optimizes the alloy composition and combines the preparation method to prepare a tin-based alloy solder containing strip Cu6Sn5, needle-shaped (Cu, Ni)6Sn5, needle-shaped Cu6(Sn,Zn)5, needle-shaped Cu6(Sn,Al)5, flake (Cu, Ni)6(Sn,Al)5, and flake (Cu, Ni)6(Sn,Zn)5 intermetallic compounds, thereby effectively improving the corrosion resistance of the tin-based alloy solder.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] On one hand, the present invention provides a corrosion-resistant tin-based alloy solder, which comprises, by mass percentage, 0.7% Cu, 0.05-0.21% Ni, one of Zn or Al, 0.05-0.15% Zn, 0.02-0.1% Al, and the remainder Sn.

[0008] Preferably, the tin-based alloy solder contains intermetallic compounds, and the intermetallic compounds include one or more of strip Cu6Sn5, needle-shaped (Cu, Ni)6Sn5, needle-shaped Cu6(Sn,Zn)5, needle-shaped Cu6(Sn,Al)5, flake (Cu, Ni)6(Sn,Al)5, and flake (Cu, Ni)6(Sn,Zn)5.

[0009] Another aspect of the present invention provides a method for preparing the above-mentioned corrosion-resistant tin-based alloy solder, the preparation method comprising the following steps:

[0010] (1) weighing alloy raw materials according to mass percentage, and vacuum melting the alloy raw materials to obtain molten alloy;

[0011] (2) cooling the molten alloy obtained in step (1) to a holding temperature and keeping the temperature thereof, and turning the alloy over during the holding process;

[0012] (3) The alloy after the heat preservation in step (2) is cooled in the furnace, and then air-cooled to obtain a corrosion-resistant tin-based alloy solder.

[0013] Preferably, in step (1), the smelting temperature is 800° C. and the smelting time is 20 min.

[0014] Preferably, in step (2), the insulation temperature is 350° C., the insulation time is 2 h, and during the insulation process, the alloy is turned over every 20 min.

[0015] Preferably, in step (3), after the insulation, the alloy is firstly furnace cooled to 250° C. and then air-cooled.

[0016] Beneficial effects of the present invention:

[0017] 1. The present invention optimizes the tin-based alloy solder formula and combines it with a preparation method to prepare a tin-based alloy solder containing strip Cu6Sn5, needle-shaped (Cu, Ni)6Sn5, needle-shaped Cu6(Sn,Zn)5, needle-shaped Cu6(Sn,Al)5, flake (Cu, Ni)6(Sn,Al)5, and flake (Cu, Ni)6(Sn,Zn)5 intermetallic compounds, which effectively enhances the chemical inertness of the alloy surface and improves the electron binding ability, thereby making it difficult for the alloy solder to undergo electrochemical interaction with the outside world, thereby improving the corrosion resistance of the alloy solder.

[0018] 2. The present invention can effectively inhibit the phase transformation of Cu6Sn5, thereby alleviating the problem of deterioration of corrosion performance caused by stress concentration at the phase interface and increased strain energy at the phase interface due to phase transformation.

[0019] 3. The cost of adding metal elements in the present invention is relatively low, which is beneficial to reducing the overall cost of tin-based alloy solder, thereby improving the corrosion resistance of tin-based alloy solder under relatively low cost conditions, which is beneficial to the industrial promotion and application of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the SEM image of the corrosion-resistant tin-based alloy solder prepared in Example 1.

[0021] Figure 2This is the SEM image of the corrosion-resistant tin-based alloy solder prepared in Example 2.

[0022] Figure 3 This is the SEM image of the corrosion-resistant tin-based alloy solder prepared in Example 3.

[0023] Figure 4 This is the SEM image of the corrosion-resistant tin-based alloy solder prepared in Example 4.

[0024] Figure 5 This is a comparison of the corrosion microstructures of the corrosion-resistant tin-based alloy solders prepared in Examples 1-4 and Comparative Example 1. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with specific embodiments.

[0026] In the examples and comparative examples of the present invention, chemical reagents not otherwise specified were all commercially available analytically pure reagents for the experiments.

[0027] In the embodiments and comparative examples of the present invention, the components of the tin-based solder are shown in Table 1.

[0028] Table 1

[0029]

[0030] Example 1

[0031] This embodiment prepares tin-based solder according to the following method:

[0032] (1) Weigh the required Sn, Cu, Ni and Zn alloy raw materials according to the composition in Table 1, put the weighed raw materials into a glass tube for vacuum packaging, and maintain the vacuum degree in the glass tube at 10 -4 Pa, put the encapsulated glass tube into a muffle furnace for melting at 800 °C and keep it warm for 20 min to ensure that the alloy is completely melted.

[0033] (2) The temperature in the furnace is then set to 350°C, the molten alloy is cooled to 350°C, and the temperature is kept for 2 hours. During the temperature holding period, the glass tube is turned over every 20 minutes.

[0034] (3) After the cooling and heat preservation is completed, the muffle furnace is turned off to heat the alloy, and the alloy is cooled to 250°C along with the furnace. The alloy is then taken out and air-cooled to room temperature to obtain a corrosion-resistant tin-based alloy solder.

[0035] The tin-based alloy solder prepared in this example was subjected to a scanning electron microscope experiment, and the results are as follows: Figure 1 As shown, through Figure 1It can be seen that the tin-based alloy solder prepared in this embodiment mainly contains flake (Cu, Ni)6(Sn, Zn)5 solid solution and Sn matrix. The IMCs (intermetallic compounds) formation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2. The microscopic morphology scanning experiment was performed on the tin-based alloy of this embodiment after corrosion, and the results were as follows: Figure 5 shown.

[0036] Example 2

[0037] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0038] The tin-based alloy solder prepared in this example was subjected to a scanning electron microscope experiment, and the results are as follows: Figure 2 As shown, through Figure 2 It can be seen that the tin-based alloy solder prepared in this embodiment mainly contains needle-shaped (Cu, Ni)6Sn5, Cu6(Sn, Zn)5, flake-shaped (Cu, Ni)6(Sn, Zn)5 solid solution and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2. The microscopic morphology scanning experiment was performed on the tin-based alloy of this embodiment after corrosion, and the results were as follows Figure 5 shown.

[0039] Example 3

[0040] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0041] The tin-based alloy solder prepared in this example was subjected to a scanning electron microscope experiment, and the results are as follows: Figure 3 As shown, through Figure 3 It can be seen that the tin-based alloy solder prepared in this embodiment mainly contains needle-shaped (Cu, Ni)6Sn5, Cu6(Sn, Al)5, flake-shaped (Cu, Ni)6(Sn, Al)5 solid solution and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2. The microscopic morphology scanning experiment was performed on the tin-based alloy of this embodiment after corrosion, and the results were as follows Figure 5 shown.

[0042] Example 4

[0043] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0044] The tin-based alloy solder prepared in this example was subjected to a scanning electron microscope experiment, and the results are as follows: Figure 4 As shown, through Figure 4It can be seen that the tin-based alloy solder prepared in this embodiment mainly contains strip-shaped Cu6Sn5, needle-shaped (Cu, Ni)6Sn5, Cu6(Sn, Al)5, sheet-shaped (Cu, Ni)6(Sn, Al)5 solid solution and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2. The microscopic morphology scanning experiment was carried out on the tin-based alloy of this embodiment after corrosion, and the results were as follows Figure 5 shown.

[0045] Example 5

[0046] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0047] The microstructure of the tin-based alloy solder prepared in this example is similar to that of the tin-based alloy solder in Example 2, and the properties are shown in Table 2.

[0048] Example 6

[0049] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0050] The microstructure of the tin-based alloy solder prepared in this example is similar to that of the tin-based alloy solder in Example 3, and the properties are shown in Table 2.

[0051] Example 7

[0052] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0053] The microstructure of the tin-based alloy solder prepared in this example is similar to that of the tin-based alloy solder in Example 4, and the properties are shown in Table 2.

[0054] Comparative Example 1

[0055] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0056] The tin-based alloy solder prepared in this embodiment mainly includes strip-shaped Cu6Sn5 and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2. The microscopic morphology scanning experiment was performed on the tin-based alloy of this embodiment after corrosion, and the results were as follows: Figure 5 shown.

[0057] Comparative Example 2

[0058] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0059] The tin-based alloy solder prepared in this embodiment mainly includes needle-shaped (Cu, Ni)6Sn5 and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2.

[0060] Comparative Example 3

[0061] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0062] The tin-based alloy solder prepared in this embodiment mainly includes strip-shaped Cu6Sn5, needle-shaped Cu6(Sn,Al)5 and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2.

[0063] Comparative Example 4

[0064] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0065] The tin-based alloy solder prepared in this embodiment mainly includes strip-shaped Cu6Sn5, needle-shaped Cu6(Sn,Zn)5 and Sn matrix. The IMCs generation heat, corrosion potential and corrosion current density of the tin-based alloy solder were tested, and the results are shown in Table 2.

[0066] Comparative Example 5

[0067] This embodiment adopts the same method as that of embodiment 1 to prepare tin-based alloy solder, and its composition ratio is shown in Table 1.

[0068] Table 2

[0069]

[0070] It can be seen from the results in Table 2 that the IMCs generation heat of the tin-based alloy solder prepared in the embodiment of the present invention is smaller than that of the tin-based alloy solder prepared in the comparative example, indicating that the tin-based alloy solder prepared in the present invention has higher thermodynamic stability.

[0071] It can be seen from the results in Table 2 that the tin-based alloy solder prepared in the embodiment of the present invention has a higher corrosion potential and a lower corrosion current density, which indicates that the corrosion rate of the tin-based alloy solder of the present invention is lower and the tin-based alloy solder of the present invention has better corrosion resistance.

[0072] It can also be seen from the results in Table 2 that when only one element of Ni, Zn and Al is added to Comparative Examples 2-4, although the thermodynamic stability and corrosion resistance are improved to a certain extent compared with Comparative Example 1, the improvement effect is limited and cannot reach the performance of the tin-based alloy solder of the present invention, indicating that under the synergistic influence of the bimetallic elements, the chemical inertness of the alloy solder surface is enhanced, and the corrosion resistance is more significantly improved. The (Cu, Ni)6(Sn, Zn)5 and (Cu, Ni)6(Sn, Al)5 intermetallic compounds play a more significant role in improving the thermodynamic stability and corrosion resistance of the tin-based alloy solder.

[0073] It can be seen from the results in Table 2 that the performance of the tin-based alloy solder of Comparative Example 5 is much lower than that of the tin-based alloy solder of the embodiment of the present invention, and the performance of the tin-based alloy solder of Comparative Example 5 is relatively close to that of the tin-based alloy solder of Comparative Example 1, indicating that Zn and Al cannot be added at the same time. Since Zn and Al are both easily corrosive elements, when the two elements exist in the alloy at the same time, on the one hand, the elements are easily combined to form new compounds, the content of alloy elements that can be dissolved in IMCs is reduced, and the modification of the chemical properties of IMCs is weakened; on the other hand, the addition of multiple easily corrosive elements will inevitably lead to an increase in the chemical activity of the alloy surface, making it more susceptible to external corrosion.

[0074] pass Figure 5 It can be seen that the degree of corrosion of the tin-based alloy solder in Comparative Example 1 is significantly deeper than that of the tin-based alloy solder in the embodiment of the present invention, which proves that the tin-based alloy solder prepared by the present invention does have a higher corrosion resistance during the actual corrosion process.

[0075] In summary, the tin-based alloy solder prepared by the present invention has excellent thermodynamic stability and corrosion resistance. When used for welding electronic components, it helps to improve the long-term reliability of electronic products.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A corrosion-resistant tin-based alloy solder, characterized in that: The tin-based alloy solder comprises, by mass percentage, 0.7% Cu, 0.05-0.21% Ni, one of Zn and Al, wherein Zn is 0.05-0.15%, Al is 0.02-0.1%, and the balance is Sn.

2. The corrosion-resistant tin-based alloy solder according to claim 1, characterized in that: The tin-based alloy solder contains intermetallic compounds, and the intermetallic compounds include one or more of strip Cu6Sn5, needle-shaped (Cu, Ni)6Sn5, needle-shaped Cu6(Sn,Zn)5, needle-shaped Cu6(Sn,Al)5, flake (Cu, Ni)6(Sn,Al)5, and flake (Cu, Ni)6(Sn,Zn)5.

3. A method for preparing a corrosion-resistant tin-based alloy solder according to claim 1-2, characterized in that: The preparation method comprises the following steps: (1) weighing alloy raw materials according to mass percentage, and vacuum melting the alloy raw materials to obtain a molten alloy; (2) cooling the molten alloy obtained in step (1) to a holding temperature and keeping the temperature thereof, and turning the alloy over during the holding process; (3) The alloy after the heat preservation in step (2) is cooled in the furnace, and then air-cooled to obtain a corrosion-resistant tin-based alloy solder.

4. The preparation method according to claim 3, characterized in that: In the step (1), the smelting temperature is 800° C. and the smelting time is 20 min.

5. The preparation method according to claim 3, characterized in that: In the step (2), the insulation temperature is 350° C., the insulation time is 2 h, and during the insulation process, the alloy is turned over every 20 min.

6. The preparation method according to claim 3, characterized in that: In the step (3), the alloy after heat preservation is firstly cooled to 250° C. in the furnace and then air-cooled.

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