Solder composition alloy and solder ball

Abstract

The invention discloses a solder composition alloy and a solder ball, and belongs to the technical field of alloys. The composition alloy of the solder provided by the embodiment of the invention comprises silver, copper, nickel, germanium, bismuth and tin, and by adjusting the content of silver, the alloy can have good heat cycle resistance and drop impact resistance; by adjusting the content of nickel, the thickness of a boundary metal part of a welding spot formed by the alloy can be effectively reduced, the situation that the welding spot is broken from the boundary metal part during a ball pushing test is avoided, and then the heat cycle resistance and the falling impact resistance of the alloy are improved; by adjusting the content of bismuth, the tensile strength and yield strength of the alloy can be improved, then the heat-resistant cycle performance of the alloy is improved, meanwhile, the melting point of the alloy is reduced, and energy needed in the welding process is reduced. Therefore, through the synergistic effect of all the components, the alloy can have good heat cycle resistance and falling impact resistance at the same time, and the performance of the alloy in other aspects can be improved.

Description

Technical Field

[0001] This application relates to the field of alloy technology, and particularly to a solder composition alloy and solder balls. Background Art

[0002] For consumer electronic products, when they are impacted or undergo multiple cycles of high and low temperature changes without damage or failure, they often leave a good impression on users due to their durability. Whether consumer electronic products are impact-resistant and temperature-resistant depends largely on the packaging method they adopt and the quality of the solder used for packaging. Among them, wafer-level chip scale packaging is a technology that uses solder balls formed by solder, and the quality of the solder used in this packaging method has a great impact on the packaging quality. Therefore, it is necessary to provide a solder composition alloy that has both heat cycle resistance and drop impact resistance. Summary of the Invention

[0003] Embodiments of this application provide a solder composition alloy and solder balls. The solder balls formed by the solder composition alloy have both good heat cycle resistance and good drop impact resistance. The technical solution is as follows:

[0004] On the one hand, a solder composition alloy is provided. The solder composition alloy includes the following components by mass fraction:

[0005] 1.5 - 2.5 wt% of silver, 0.5 - 1.0 wt% of copper, 0.01 - 0.05 wt% of nickel, 0.005 - 0.015 wt% of germanium, 0.05 - 1.0 wt% of bismuth, and the balance is tin.

[0006] In a possible implementation, the solder composition alloy further includes 0.005 - 0.1 wt% of magnesium.

[0007] In another possible implementation, the solder composition alloy further includes 0.005 - 0.1 wt% of zinc.

[0008] In another possible implementation, the mass fraction of the silver is 1.7 - 2.3 wt%.

[0009] In another possible implementation, the mass fraction of the copper is 0.6 - 0.9 wt%.

[0010] In another possible implementation, the mass fraction of the nickel is 0.02 - 0.04 wt%.

[0011] In another possible implementation, the mass fraction of the germanium is 0.008 - 0.012 wt%.

[0012] In another possible implementation, the mass fraction of bismuth is 0.2 to 0.8 wt%.

[0013] On the other hand, a solder ball is provided, which is formed of an alloy composed of the solder described in any one of the above.

[0014] In a possible implementation, the diameter of the solder ball is 0.05 to 2.0 mm.

[0015] The embodiments of the present application provide a solder composition alloy, which includes silver, copper, nickel, germanium, bismuth and tin. By adjusting the content of silver, the alloy can have good heat cycle performance and drop impact resistance; by adjusting the content of copper, the wettability of the alloy can be improved and the soldering performance of the alloy can be improved; by adjusting the content of nickel, the thickness of the interfacial metal part of the solder joint formed by the alloy can be effectively reduced, avoiding the fracture of the solder joint at the interfacial metal part during the ball push test, and further improving the heat cycle performance and drop impact resistance of the alloy; by adjusting the content of germanium, the antioxidant ability of the alloy in air can be enhanced; by adjusting the content of bismuth, the tensile strength and yield strength of the alloy can be increased, thereby improving the heat cycle performance of the alloy, while reducing the melting point of the alloy and reducing the energy required during the welding process. It can be seen that through the synergistic effect between the components, the alloy can not only have good heat cycle performance and drop impact resistance at the same time, but also improve the performance of the alloy in other aspects.

[0016] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present disclosure. Detailed Embodiments

[0017] To make the technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below.

[0018] On the one hand, the embodiments of the present application provide a solder composition alloy, which includes the following components with the following mass fractions:

[0019] 1.5 to 2.5 wt% of silver, 0.5 to 1.0 wt% of copper, 0.01 to 0.05 wt% of nickel, 0.005 to 0.015 wt% of germanium, 0.05 to 1.0 wt% of bismuth, and the balance is tin.

[0020] The embodiments of the present application provide a solder composition alloy, which includes silver, copper, nickel, germanium, bismuth, and tin. By adjusting the content of silver, the alloy can have good heat cycle resistance and drop impact resistance; by adjusting the content of copper, the wettability of the alloy can be improved, and the soldering property of the alloy can be improved; by adjusting the content of nickel, the thickness of the interfacial metal part of the solder joint formed by the alloy can be effectively reduced, avoiding the fracture of the solder joint at the interfacial metal part during the ball push test, thereby improving the heat cycle resistance and drop impact resistance of the alloy; by adjusting the content of germanium, the antioxidant ability of the alloy in air can be enhanced; by adjusting the content of bismuth, the tensile strength and yield strength of the alloy can be increased, thereby improving the heat cycle resistance of the alloy, and at the same time reducing the melting point of the alloy and reducing the energy required during the welding process. Thus, through the synergistic effect of each component, the alloy can not only have good heat cycle resistance and drop impact resistance at the same time, but also improve the performance of the alloy in other aspects.

[0021] In a possible implementation, the mass fraction of silver can be 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2.0wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt%, 2.5wt%.

[0022] In this implementation, the mass fraction of silver can be 1.7 - 2.3wt%. Specifically, the mass fraction of silver can be 1.9 - 2.1wt%. Further, the mass fraction of silver can be 2.0wt%.

[0023] In the embodiments of the present application, if the content of silver is less than 1.5wt%, the heat cycle resistance of the alloy will decrease; if the content of silver exceeds 2.5wt%, the drop impact resistance of the alloy will decrease.

[0024] In a possible implementation, the mass fraction of copper can be 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, 0.85wt%, 0.9wt%, 0.95wt%, 1.0wt%.

[0025] In this implementation, the mass fraction of copper can be 0.6 - 0.9wt%. Specifically, the mass fraction of copper can be 0.7 - 0.8wt%. Further, the mass fraction of copper can be 0.75wt%.

[0026] In the embodiments of the present application, copper helps to improve the wettability of the alloy and the effect of improving the alloy brazability. If the copper content is less than 0.5 wt%, the mechanical properties of the alloy will be significantly reduced, unable to meet the requirements of practical applications; if the copper content exceeds 1 wt%, the solder balls will show poor fluidity during the melting process, forming a paste-like substance, resulting in insufficient wettability.

[0027] In a possible implementation, the mass fraction of nickel can be 0.01 wt%, 0.015 wt%, 0.02 wt%, 0.025 wt%, 0.03 wt%, 0.035 wt%, 0.04 wt%, 0.045 wt%, 0.05 wt%.

[0028] In this implementation, the mass fraction of nickel can be 0.02 - 0.04 wt%. Specifically, the mass fraction of nickel can be 0.03 - 0.04 wt%. Further, the mass fraction of nickel can be 0.04 wt%.

[0029] In the embodiments of the present application, the above content of nickel can effectively reduce the thickness of the intermetallic part of the solder joints formed by the alloy, thus avoiding the situation of the solder joints breaking from the intermetallic part during the ball push test. If the solder alloy composed of the solder has good ductility, or the solder joints formed by welding with the solder alloy break from the solder part during the ball push test instead of brittle fracture from the intermetallic (Intermetallic Compound, IMC) part, then the solder joints can not only have better performance in the temperature cycle test, but also have good performance in the drop impact test. Therefore, the above content of nickel can also improve the heat cycle resistance and drop impact resistance of the solder alloy.

[0030] In a possible implementation, the mass fraction of germanium can be 0.005 wt%, 0.006 wt%, 0.007 wt%, 0.008 wt%, 0.009 wt%, 0.01 wt%, 0.011 wt%, 0.012 wt%, 0.013 wt%, 0.014 wt%, 0.015 wt%.

[0031] In this implementation, the mass fraction of germanium can be 0.008 - 0.012 wt%. Further, the mass fraction of germanium can be 0.01 wt%.

[0032] It should be noted that during the semiconductor packaging process, flux is usually used to remove the oxide film formed by the solder alloy during storage. If the oxide film is not completely removed, it will affect the wettability of the alloy, reduce the fusion performance, and cause welding defects. In addition, the appearance of the solder joints is equally important. In the tin-based solder alloy, tin is easy to react with oxygen to form yellow oxides, and this discoloration can be detected by visual inspection and is usually regarded as unqualified.

[0033] In this application, germanium is added to the alloy, and germanium in the above content can effectively improve the antioxidant ability of the tin-based solder in air and can also maintain a silvery-white surface luster for a long time at high temperatures.

[0034] In a possible implementation, the mass fraction of bismuth can be 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%.

[0035] In the embodiments of this application, bismuth and other components act synergistically, and can have a relatively high shear force value in the shear force test, while having better tensile strength and yield strength. The shear force that the solder composition alloy can withstand in the ball shear test and the average hardness of the upper edge of the interfacial metal layer can be further improved. If the properties such as the yield strength and tensile strength of the solder composition alloy are better, when the solder composition alloy is used for welding to form a solder joint, when the solder joint can obtain a large shear force in the ball shear test (Ball Shear Test), the solder joint can often have better performance in the thermal cycling test (Thermal Cycling Test, TCT) and also has better resistance to temperature aging. Therefore, bismuth in the above content can further improve the heat resistance cycling performance of the solder composition alloy.

[0036] In addition, the addition of bismuth element can reduce the melting point of the alloy, which helps to reduce the energy required in the welding process, and at the same time can also reduce the welding temperature and reduce the thermal damage to the substrate material. In the solder composition alloy with a low bismuth content, the bismuth content is less than 0.2wt%, although it can slightly improve the mechanical strength of the solder composition alloy, the improvement of the shear strength is limited. On the contrary, in the solder composition alloy with a high bismuth content, the bismuth content is higher than 1.0wt%, then the solder composition alloy will break at the interfacial metal part during the ball shear test due to excessive mechanical strength.

[0037] Based on this, in the embodiments of this application, the mass fraction of bismuth can be 0.2 - 0.8wt%. Specifically, the mass fraction of bismuth can be 0.4 - 0.6wt%. Further, the mass fraction of bismuth can be 0.5wt%.

[0038] In a possible implementation, the solder composition alloy further includes 0.005 - 0.1wt% of magnesium.

[0039] In this implementation, the mass fraction of magnesium can be 0.005 wt%, 0.006 wt%, 0.007 wt%, 0.008 wt%, 0.009 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%.

[0040] In a possible implementation, the solder composition alloy further includes 0.005 - 0.1 wt% of zinc.

[0041] In this implementation, the mass fraction of zinc can be 0.005 wt%, 0.006 wt%, 0.007 wt%, 0.008 wt%, 0.009 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%.

[0042] In the embodiments of the present application, the solder composition alloy may include at least one of magnesium and zinc in the above contents.

[0043] When the solder composition alloy includes at least one of magnesium and zinc, magnesium and / or zinc can participate in the reaction of the interfacial metal layer, refine the metal grains, make the growth of the interfacial metal more delicate and uniform, and thus further improve its drop resistance.

[0044] In summary, the present application adjusts the ratio of each component in the alloy to improve the physical properties of the alloy. When the solder joints formed by using it are reflow soldered, the solder joints can have better performance in the temperature cycle test and also have good performance in the drop impact test (Drop Test), so that the alloy has good heat cycle resistance and drop impact resistance at the same time.

[0045] On the other hand, the embodiments of the present application provide a solder ball, which is formed by the above solder composition alloy.

[0046] In a possible implementation, the diameter of the solder ball is 0.05 - 2.0 mm.

[0047] In this implementation, the diameter of the solder ball is 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm.

[0048] To make the technical solutions and advantages of this application clearer, the following will be elaborated in detail through specific embodiments.

[0049] In the following specific embodiments, operations not specified in terms of conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. Raw materials not specified in terms of manufacturer and specifications are all conventional products that can be obtained through commercial procurement.

[0050] Example 1

[0051] The solder composition alloy provided in this example includes the following components by mass fraction:

[0052] 1.5 wt% silver, 0.5 wt% copper, 0.01 wt% nickel, 0.005 wt% germanium, 0.05 wt% bismuth, with the balance being tin.

[0053] Example 2

[0054] The solder composition alloy provided in this example includes the following components by mass fraction:

[0055] 1.5 wt% silver, 0.5 wt% copper, 0.01 wt% nickel, 0.005 wt% germanium, 0.1 wt% bismuth, with the balance being tin.

[0056] Example 3

[0057] The solder composition alloy provided in this example includes the following components by mass fraction:

[0058] 1.5 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, with the balance being tin.

[0059] Example 4

[0060] The solder composition alloy provided in this example includes the following components by mass fraction:

[0061] 1.5 wt% silver, 1 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 1 wt% bismuth, with the balance being tin.

[0062] Example 5

[0063] The solder composition alloy provided in this example includes the following components by mass fraction:

[0064] 2 wt% silver, 0.5 wt% copper, 0.01 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, with the balance being tin.

[0065] Example 6

[0066] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0067] 2 wt% silver, 0.5 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0068] Example 7

[0069] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0070] 2 wt% silver, 0.75 wt% copper, 0.01 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0071] Example 8

[0072] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0073] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.005 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0074] Example 9

[0075] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0076] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.05 wt% bismuth, and the balance is tin.

[0077] Example 10

[0078] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0079] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.1 wt% bismuth, and the balance is tin.

[0080] Example 11

[0081] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0082] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0083] Example 12

[0084] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0085] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 1 wt% bismuth, and the balance is tin.

[0086] Example 13

[0087] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0088] 2 wt% silver, 1 wt% copper, 0.01 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0089] Example 14

[0090] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0091] 2 wt% silver, 1 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0092] Example 15

[0093] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0094] 2.5 wt% silver, 0.5 wt% copper, 0.01 wt% nickel, 0.005 wt% germanium, 0.05 wt% bismuth, and the balance is tin.

[0095] Example 16

[0096] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0097] 2.5 wt% silver, 0.5 wt% copper, 0.01 wt% nickel, 0.005 wt% germanium, 0.1 wt% bismuth, and the balance is tin.

[0098] Example 17

[0099] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0100] 2.5 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, and the balance is tin.

[0101] Example 18

[0102] The solder composition alloy provided by this embodiment includes the following components by mass fraction:

[0103] 2.5 wt% silver, 1 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 1 wt% bismuth, the balance being tin.

[0104] Example 19

[0105] The solder composition alloy provided in this example includes the following components by mass fraction:

[0106] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.01 wt% magnesium, the balance being tin.

[0107] Example 20

[0108] The solder composition alloy provided in this example includes the following components by mass fraction:

[0109] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.05 wt% magnesium, the balance being tin.

[0110] Example 21

[0111] The solder composition alloy provided in this example includes the following components by mass fraction:

[0112] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.1 wt% magnesium, the balance being tin.

[0113] Example 22

[0114] The solder composition alloy provided in this example includes the following components by mass fraction:

[0115] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.01 wt% zinc, the balance being tin.

[0116] Example 23

[0117] The solder composition alloy provided in this example includes the following components by mass fraction:

[0118] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.05 wt% zinc, the balance being tin.

[0119] Example 24

[0120] The solder composition alloy provided in this embodiment includes the following components by mass fraction:

[0121] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.1 wt% zinc, and the balance is tin.

[0122] Example 25

[0123] The solder composition alloy provided in this embodiment includes the following components by mass fraction:

[0124] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.05 wt% magnesium, 0.05 wt% zinc, and the balance is tin.

[0125] Example 26

[0126] The solder composition alloy provided in this embodiment includes the following components by mass fraction:

[0127] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.1 wt% magnesium, 0.05 wt% zinc, and the balance is tin.

[0128] Example 27

[0129] The solder composition alloy provided in this embodiment includes the following components by mass fraction:

[0130] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.05 wt% magnesium, 0.1 wt% zinc, and the balance is tin.

[0131] Example 28

[0132] The solder composition alloy provided in this embodiment includes the following components by mass fraction:

[0133] 2 wt% silver, 0.75 wt% copper, 0.04 wt% nickel, 0.01 wt% germanium, 0.5 wt% bismuth, 0.1 wt% magnesium, 0.1 wt% zinc, and the balance is tin.

[0134] Comparative Example 1

[0135] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0136] 1 wt% silver, 0.5 wt% copper, 0.05 wt% nickel, 0.01 wt% germanium, and the balance is tin.

[0137] Comparative Example 2

[0138] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0139] 1.2 wt% silver, 0.5 wt% copper, 0.05 wt% nickel, 0.01 wt% germanium, and the balance is tin.

[0140] Comparative Example 3

[0141] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0142] 3 wt% silver, 0.5 wt% copper, 0.05 wt% nickel, 0.01 wt% germanium, and the balance is tin.

[0143] Comparative Example 4

[0144] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0145] 3 wt% silver, 0.5 wt% copper, 0.01 wt% germanium, 3 wt% bismuth, and the balance is tin.

[0146] Comparative Example 5

[0147] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0148] 3 wt% silver, 0.5 wt% copper, 0.05 wt% nickel, 0.01 wt% germanium, 3 wt% bismuth, and the balance is tin.

[0149] Comparative Example 6

[0150] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0151] 4 wt% silver, 0.5 wt% copper, 0.05 wt% nickel, 0.01 wt% germanium, and the balance is tin.

[0152] Comparative Example 7

[0153] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0154] 4 wt% silver, 0.5 wt% copper, 0.01 wt% germanium, 3 wt% bismuth, and the balance is tin.

[0155] Comparative Example 8

[0156] The solder composition alloy provided in this comparative example includes the following components by mass fraction:

[0157] 4 wt% silver, 0.5 wt% copper, 0.05 wt% nickel, 0.01 wt% germanium, 3 wt% bismuth, the balance being tin.

[0158] The compositions of the solder composition alloys corresponding to Examples 1-28 and Comparative Examples 1-8 can also be seen in Table 1 below. The tin balls formed in Examples 1-28 and Comparative Examples 1-8 of this application were subjected to a drop test. The tin balls formed in Examples 3, 6, 8-18, 20, 23, 25 and Comparative Examples 1-3, 5-6, 8 were subjected to a thermal cycle test. The melting points of the solder composition alloys corresponding to Examples 1-28 and Comparative Examples 1-8 were analyzed. The test results can also be seen in Table 1.

[0159] Table 1

[0160]

[0161]

[0162] Among them, Cu / OSP is the substrate UBM (Under Bump Metallurgy) material.

[0163] The thermal cycle test in this application is to place the tin balls (diameter 0.25 mm) formed in Examples 3, 6, 8-18, 20, 23, 25 and Comparative Examples 1-3, 5-6, 8 on the ball grid array pads, and solder them to the PCB (Printed Circuit Board) by SMT (Surface Mounted Technology), and then perform a temperature cycle test from -40°C to 125°C, and finally obtain the temperature cycle test results.

[0164] It can be seen from Example 3, Example 11 and Example 17 that: within the range of 1.5-2.5 wt%, the higher the silver content, the better the thermal cycle performance of the tin balls. It can also be seen from Comparative Examples 1-3 and 6 that: the higher the silver content, the better the thermal cycle performance of the tin balls.

[0165] Moreover, within the range of 0.05-1.0 wt% of bismuth element, it can also effectively improve the thermal cycle performance of the tin balls. Comparing Example 20 with Comparative Example 3, Example 20 added 2.0 wt% silver and 0.5 wt% bismuth; Comparative Example 3 added 3.0 wt% Ag. Comparing the two, Example 20 with a lower silver content is at the same level as Comparative Example 3 with a higher silver content in terms of the number of thermal cycles when adding 0.5 wt% bismuth.

[0166] In the anti-drop test of this application, the solder balls (with a diameter of 0.25 mm) prepared in Examples 1 to 25 and Comparative Examples 1 to 8 were placed on the solder pads and soldered to the PCB board by SMT. According to the JEDEC standard, an acceleration impact of 1500G ± 20% was applied. If the resistance value was > 1000Ω for four consecutive times, it was regarded as failure, and the final anti-drop test results were obtained.

[0167] As can be seen from Table 1: The lower the silver content, the better the anti-drop performance of the solder balls. The silver content in Example 20 is relatively low, and the addition of trace elements such as Ni, Mg, and Zn can inhibit the growth of the interfacial IMC (intermetallic compound) during welding and refine the interfacial IMC grains. While in Comparative Example 3, the silver content is high and only a trace amount of Ni element is added. In terms of the number of anti-drop times, the anti-drop performance of Example 20 is much higher than that of Comparative Example 3.

[0168] Moreover, from Comparative Examples 1 - 3 and 6, it can also be seen that: The lower the silver content, the higher the number of anti-drop times of the solder balls. In addition, when the silver content exceeds 2.5 wt%, the number of anti-drop times of the solder balls will decrease significantly. This also shows that: When the silver content is in the range of 1.5 - 2.5 wt%, the anti-drop times and heat resistance cycle times of the solder balls can be balanced, enabling the solder balls to have good heat resistance cycle performance and drop impact resistance at the same time.

[0169] In this application, the solder compositions corresponding to Examples 1 to 28 and Comparative Examples 1 to 8 were analyzed for their melting points using a differential scanning calorimetry (DSC). As can be seen from Table 1: The addition of bismuth can also effectively reduce the melting point of the solder balls. On the one hand, it can reduce energy consumption and carbon emissions during the manufacturing process; on the other hand, during the reflow and SMT processes, it can reduce the possibility of chip failure caused by substrate warping due to excessive reflow temperature.

[0170] In summary, by adjusting the content of each component in this application to enable each component to play a synergistic role, the heat resistance cycle performance and drop impact resistance of the solder balls formed by the solder composition alloy can be improved. At the same time, the melting point of the alloy can be reduced, the energy required during the welding process can be reduced, and the welding temperature can also be reduced, thereby reducing the thermal damage to the substrate material.

[0171] The above is only for the convenience of those skilled in the art to understand the technical solution of this application and is not intended to limit this application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims

1. A solder composition alloy, characterized in that, The solder composition alloy comprises the following components by mass fraction: 1.5 to 2.5 wt% of silver, 0.5 to 1.0 wt% of copper, 0.01 to 0.05 wt% of nickel, 0.005 to 0.015 wt% of germanium, 0.05 to 1.0 wt% of bismuth, and the balance being tin.

2. The solder composition alloy according to claim 1, characterized in that, The solder composition alloy further comprises 0.005 to 0.1 wt% of magnesium.

3. The solder composition alloy according to claim 1, characterized in that, The solder composition alloy further comprises 0.005 to 0.1 wt% of zinc.

4. The solder composition alloy according to claim 1, characterized in that, The mass fraction of the silver is 1.7 to 2.3 wt%.

5. The solder composition alloy according to claim 1, characterized in that, The mass fraction of the copper is 0.6 to 0.9 wt%.

6. The solder composition alloy according to claim 1, characterized in that, The mass fraction of the nickel is 0.02 to 0.04 wt%.

7. The solder composition alloy according to claim 1, characterized in that, The mass fraction of the germanium is 0.008 to 0.012 wt%.

8. The solder composition alloy according to claim 1, characterized in that, The mass fraction of the bismuth is 0.2 to 0.8 wt%.

9. A solder ball, characterized in that, The solder ball is formed of the solder composition alloy according to any one of claims 1 to 8.

10. The solder ball according to claim 9, wherein The diameter of the solder ball is 0.05 to 2.0 mm.

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