Alloy typed solder ball having low melting point and Manufacturing method thereof

Abstract

The present invention relates to an indium (In)-based low-melting point alloy type solder ball and a method for manufacturing the same. A low-melting point solder ball according to one embodiment of the present invention comprises indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge), and comprises an alloy represented by the following chemical formula 1. [Chemical Formula 1] Ina[Sn, Bi]bAlcGed In Chemical Formula 1, [Sn, Bi] means optionally including tin or bismuth, and a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%.

Description

Technology Field

[0001] The present invention relates to an indium (In)-based low-melting-point alloy type solder ball and a method for manufacturing the same. Background Technology

[0003] Recently, active research is being conducted on bonding technology in semiconductors, which connects chips and package substrates to transmit electrical signals.

[0004] Initially, this bonding technology used the PGA (Pin Grid Array) method, in which pointed pins are arranged and connected on the chip. However, as the integration density of semiconductor devices increased, it evolved into the BGA (Ball Grid Array) method, in which ball-shaped solder balls are soldered to the bonding pads of the chip.

[0005] The BGA (Ball Grid Array) method has the advantage of being thin and lightweight because it does not require a socket. For this reason, research on solder balls used in the BGA (Ball Grid Array) method is actively being conducted.

[0006] Generally, solder balls are made and used from alloys containing 80 to 99 wt% tin (Sn). However, tin (Sn) has the disadvantage of poor performance as a solder ball due to its low electrical conductivity. In addition, tin (Sn) has low hardness and thermal cycling characteristics, and is susceptible to oxidation, which causes corrosion easily, resulting in cracks and reduced reliability due to weakened adhesion.

[0007] Therefore, in recent years, alloys for solder balls with various compositions have been developed to solve the problems of solder balls with tin (Sn) as the main component, but there were limitations in sufficiently resolving the issues of solder balls with tin (Sn) as the main component.

[0008] Therefore, there is an increasing need to develop alloy compositions for solder balls that are resistant to thermal shock or corrosion while maintaining excellent properties regarding electrical conductivity, wettability, hardness, and melting point. Prior art literature

[0010] Korean Registered Patent No. 10-1275302 (Publication Date: June 17, 2013) The problem to be solved

[0011] The present invention aims to provide a low-melting point alloy type solder ball having excellent physical properties such as electrical conductivity and hardness while having a low melting point, and a method for manufacturing the same, which is composed mainly of indium (In) and includes aluminum (Al) along with other specific metals in an optimal compositional ratio. means of solving the problem

[0013] A low-melting point solder ball according to one embodiment of the present invention for solving the above-mentioned problem comprises indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge), and is characterized as an alloy in which the content of indium is greater than the content of tin or bismuth.

[0014] The above alloy is characterized by being represented by the following chemical formula 1.

[0015] [Chemical Formula 1]

[0016] In a [Sn, Bi] b Al c Ge d

[0017] In Chemical Formula 1, [Sn, Bi] means optionally including tin or bismuth, and a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%.

[0018] The above alloy is characterized by further including any one selected from copper (Cu), gold (Au) and silver (Ag), and being represented by the following chemical formula 2.

[0019] [Chemical Formula 2]

[0020] In a [Sn, Bi] b Al c Ge d [Cu, Au, Ag] e

[0021] In Chemical Formula 2, [Cu, Au, Ag] means optionally including any one of copper, gold, and silver, and a, b, c, d, and e represent the content of each metal in the alloy, b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, e is 0.01 to 0.5 wt%, and a is (100-bcde) wt%.

[0022] At this time, the average particle size of the solder ball is characterized by being 50 to 200 μm.

[0023] In addition, the solder ball is characterized by having a melting point of 140.0℃ to 170.0℃, a hardness of 3.0 to 32.0 HV / 0.5gf, an electrical conductivity of 11.0 to 23.0 %IACS, and a wettability in which the force (Fmax) of the solder ball pulling the molten solder is 2.0 to 2.5 mN, and preferably, the solder ball is characterized by having a hardness of 3.23 to 31.51 HV / 0.5gf, an electrical conductivity of 11.48 to 22.14 %IACS, and a wettability in which the force (Fmax) of the solder ball pulling the molten solder is 2.16 to 2.42 mN.

[0025] Meanwhile, a method for manufacturing a low-melting point solder ball according to one embodiment of the present invention comprises: a first step of manufacturing an AlGe alloy and an InBi alloy or an InSn alloy, respectively; a second step comprising a first process of manufacturing an alloy by alloying the AlGe alloy and the InBi alloy or alloying the AlGe alloy and the InSn alloy, wherein the alloy comprises indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge), wherein the content of indium is greater than the content of tin or bismuth; and a third step of forming the alloy manufactured in the second step into a solder ball shape.

[0026] At this time, the alloy produced in the first process of the second step is characterized by being represented by the following chemical formula 1.

[0027] [Chemical Formula 1]

[0028] In a [Sn, Bi] b Al c Ge d

[0029] In Chemical Formula 1, [Sn, Bi] means optionally including tin or bismuth, and a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%.

[0030] And, the above second step is characterized by further including a second step of manufacturing an alloy represented by the following chemical formula 2 by adding one selected from copper (Cu), gold (Au), and silver (Ag) to the alloy represented by chemical formula 1 after carrying out the above first step, and then alloying.

[0031] [Chemical Formula 2]

[0032] In a [Sn, Bi] b Alc Ge d [Cu, Au, Ag] e

[0033] In Chemical Formula 2, [Cu, Au, Ag] means optionally including any one of copper, gold, and silver, and a, b, c, d, and e represent the content of each metal in the alloy, b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, e is 0.01 to 0.5 wt%, and a is (100-bcde) wt%.

[0034] At this time, the alloy formed into a solder ball shape in the third step is characterized by having an average particle size of 50 to 200 μm. Effects of the invention

[0036] According to an embodiment of the present invention, by manufacturing a solder ball using indium as the main component, which has a relatively lower melting point than tin—a component used as the main component in conventional lead-free solder balls—and has good electrical conductivity, there is an effect of expecting improved electrical conductivity while maintaining a low melting point.

[0037] In addition, by incorporating alloying elements with excellent corrosion resistance, such as aluminum and germanium, as alloying components, it is possible to improve hardness and wettability while maintaining a low melting point and enhanced electrical conductivity, and to manufacture a solder ball with high reliability that is highly resistant to thermal shock and corrosion. Brief explanation of the drawing

[0039] FIG. 1 is a flowchart showing a method for manufacturing a low-melting-point solder ball according to one embodiment of the present invention, and FIG. 2 is a photograph showing a quaternary alloy solder ball manufactured according to Example 6, and FIG. 3 is a photograph showing a pentatonic alloy solder ball manufactured according to Example 7, and FIG. 4 is a graph showing the results of measuring the electrical conductivity of solder balls prepared according to Comparative Example 1 and Examples 1 to 3, and FIG. 5 is a graph showing the results of measuring the electrical conductivity of solder balls prepared according to Comparative Example 1 and Examples 4 to 6, and FIG. 6 is a graph showing the results of measuring the electrical conductivity of solder balls prepared according to Comparative Example 1 and Examples 7 to 9, and FIG. 7 is a graph showing the results of measuring the hardness of solder balls prepared according to Comparative Example 1 and Examples 1 to 3, and FIG. 8 is a graph showing the results of measuring the hardness of solder balls prepared according to Comparative Example 1 and Examples 4 to 6, and FIG. 9 is a graph showing the results of measuring the hardness of solder balls manufactured according to Comparative Example 1 and Examples 7 to 9. Specific details for implementing the invention

[0040] Preferred embodiments of the present invention are described in detail below. Terms such as "first," "second," etc., are used merely to distinguish and describe various components, and the components of the present invention are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. In this application, terms such as "comprising" are intended to indicate the existence of features, steps, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, steps, or combinations thereof. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains.

[0042] A low-melting point solder ball according to one embodiment of the present invention is composed of a quaternary alloy comprising indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge). In addition, a low-melting point solder ball according to another embodiment of the present invention is composed of a pentary alloy comprising indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge), along with any one selected from copper (Cu), gold (Au), and silver (Ag).

[0043] Specifically, a low-melting-point solder ball composed of a quaternary alloy can be represented by the following chemical formula 1.

[0044] [Chemical Formula 1]

[0045] In a [Sn, Bi] b Al c Ge d

[0046] In the above chemical formula 1, [Sn, Bi] means optionally including tin or bismuth. Also, in chemical formula 1, a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%.

[0047] To elaborate, the low-melting point solder ball made of a quaternary alloy consists of tin (Sn) or bismuth (Bi): 1.0 to 20.0 wt%, aluminum (Al): 0.1 to 5.0 wt%, germanium (Ge): 0.01 to 1.5 wt%, and the remainder being indium (In). In this case, the low-melting point solder ball may inevitably contain impurities due to the manufacturing process.

[0048] In the present invention, by using indium (In) as the main component, a relatively lower melting point can be maintained compared to conventional solder balls using tin (Sn) as the main component.

[0049] Tin (Sn) and bismuth (Bi) are alloying elements that are optionally included in the solder ball, and by optionally including tin (Sn) and bismuth (Bi) in the alloy, the mechanical properties of the solder ball are improved through solid solution hardening.

[0050] If the content of optionally contained tin (Sn) or bismuth (Bi) is less than 1.0 wt%, the improvement in mechanical properties due to the addition of alloy components cannot be expected, and if the content exceeds 20 wt%, the melting point increases, so the low melting point effect compared to conventional solder balls using tin (Sn) as the main component cannot be expected. Therefore, it is preferable to maintain the content of optionally contained tin (Sn) or bismuth (Bi) at 1.0 to 20.0 wt%, preferably at 3.0 to 10.0 wt%, more preferably at 4.0 to 6.0 wt%, and even more preferably at 5.0 wt%.

[0051] Aluminum (Al) is an alloying element included to improve the oxidation resistance of the solder ball. If the content of aluminum (Al) is less than 1.0 wt%, the improvement in oxidation resistance due to the addition of alloying elements cannot be expected, and if the content exceeds 5.0 wt%, a problem may arise where the hardness increases rapidly. Therefore, it is preferable to maintain the content of aluminum (Al) at 0.1 to 5.0 wt%, preferably at 0.1 to 4.0 wt%, more preferably at 0.7 to 3.6 wt%, and even more preferably at 0.7 to 2.1 wt%.

[0052] Germanium (Ge) is an alloying element included to improve the oxidation resistance of solder balls, just like aluminum (Al). If the germanium (Ge) content is less than 0.01 wt%, the improvement in oxidation resistance due to the addition of alloying elements cannot be expected, and if the content exceeds 1.5 wt%, a problem may arise where the hardness becomes too high. Therefore, it is preferable to maintain the germanium (Ge) content at 0.01 to 1.5 wt%, preferably at 0.1 to 1.5 wt%, more preferably at 0.3 to 1.4 wt%, and even more preferably at 0.3 to 0.9 wt%.

[0054] Meanwhile, a low-melting point solder ball made of a pentatonic alloy can be represented by the following chemical formula 2.

[0055] [Chemical Formula 2]

[0056] In a [Sn, Bi] b Al c Ge d [Cu, Au, Ag] e

[0057] In Chemical Formula 2, [Cu, Au, Ag] means optionally including any one of copper, gold, and silver, and a, b, c, d, and e represent the content of each metal in the alloy, b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, e is 0.01 to 0.5 wt%, and a is (100-bcde) wt%.

[0058] To elaborate, the low-melting point solder ball made of a pentatonic alloy consists of tin (Sn) or bismuth (Bi): 1.0 to 20.0 wt%, aluminum (Al): 0.1 to 5.0 wt%, germanium (Ge): 0.01 to 1.5 wt%, any one of copper (Cu), gold (Au) and silver (Ag): 0.01 to 0.5 wt%, and the remainder being indium (In). In this case, the low-melting point solder ball may also inevitably contain impurities due to the manufacturing process.

[0059] Copper (Cu), gold (Au), or silver (Ag) additionally contained in low-melting-point solder balls made of pentatonic alloys are alloying elements included to improve the electrical conductivity of the solder balls. If the content of additional alloying elements is less than 0.01 wt%, the effect of improving electrical conductivity due to the addition of alloying components cannot be expected, and if the content exceeds 0.5 wt%, a problem of increased hardness may occur. Therefore, it is preferable to maintain the content of additional alloying elements such as copper (Cu), gold (Au), or silver (Ag) at 0.01 to 0.5 wt%, preferably at 0.05 to 0.3 wt%, more preferably at 0.07 to 0.2 wt%, and even more preferably at 0.1 wt%.

[0061] Meanwhile, the low-melting point solder ball composed of the above-mentioned components and content is molded to have an average particle size of 50 to 200 μm.

[0062] Accordingly, the solder ball can maintain a melting point of 140.0°C to 170.0°C, preferably 142.0°C to 165.2°C.

[0063] In addition, the solder ball has a hardness of 3.0 to 32.0 HV / 0.5gf, preferably 3.23 to 31.51 HV / 0.5gf, an electrical conductivity of 11.0 to 23.0 %IACS, preferably 11.48 to 22.14 %IACS, and a wettability in which the force (Fmax) of the solder ball pulling the molten solder is 2.0 to 2.5 mN, preferably 2.16 to 2.42 mN.

[0065] Next, a method for manufacturing a low-melting point solder ball having the above-mentioned components and content will be explained with reference to the drawings.

[0066] FIG. 1 is a flowchart showing a method for manufacturing a low-melting point solder ball according to one embodiment of the present invention.

[0067] As illustrated in FIG. 1, a low-melting point solder ball according to one embodiment of the present invention comprises a method for manufacturing a low-melting point solder ball composed of a previously described quaternary alloy, the method comprising: a first step of manufacturing an AlGe alloy and an InBi alloy or an InSn alloy, respectively; a second step including a first process of manufacturing an alloy represented by the following chemical formula 1 by alloying the AlGe alloy and the InBi alloy or alloying the AlGe alloy and the InSn alloy; and a third step of forming the alloy manufactured in the second step into a solder ball shape.

[0068] [Chemical Formula 1]

[0069] In a [Sn, Bi] b Al c Ge d

[0070] In Chemical Formula 1, [Sn, Bi] means optionally including tin or bismuth, and a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%.

[0071] In the first step of manufacturing a low-melting point solder ball made of a quaternary alloy represented by Chemical Formula 1, a pre-alloy such as an AlGe alloy, an InBi alloy, or an InSn alloy is prepared first. At this time, the pre-alloys such as the AlGe alloy, the InBi alloy, or the InSn alloy can each be prepared in a solid state, but for the simplification and convenience of the manufacturing process, they can be prepared in a liquid state, i.e., as a molten metal, and then each alloy can be mixed.

[0072] For example, an AlGe alloy is prepared by adjusting the composition ratio of aluminum (Al) and germanium (Ge) in a graphite crucible or an alumina crucible, and then heating to 940 to 1000°C, where the aluminum (Al) and germanium (Ge) melt.

[0073] Then, while the crucible in which the AlGe alloy is molten is cooling in the first process of the second stage, an InBi alloy or an InSn alloy with a controlled composition ratio is loaded into the crucible in which the AlGe alloy is molten to form a quaternary alloy represented by Chemical Formula 1. At this time, the condition for loading the InBi alloy or InSn alloy into the crucible is that the temperature of the molten AlGe alloy inside the crucible is preferably at a level of 500 to 700°C.

[0074] In addition, in the third step, the alloy produced in the second step is formed into a solder ball. At this time, the alloy produced in the second step can be formed into a solder ball by forming it in a liquid state or by cooling it into a solid state and then forming it. For example, the third step can be performed using an orifice compression method to form a solder ball with an average particle size of 50 to 200 μm.

[0076] Meanwhile, the method for manufacturing a low-melting point solder ball made of the pentatonic alloy described above further includes a second process of manufacturing an alloy represented by the following chemical formula 2 by adding any one selected from copper (Cu), gold (Au), and silver (Ag) to the alloy represented by chemical formula 1 after carrying out the first process in the aforementioned second step, and then alloying.

[0077] [Chemical Formula 2]

[0078] In a [Sn, Bi] b Al c Ge d [Cu, Au, Ag] e

[0079] In Chemical Formula 2, [Cu, Au, Ag] means optionally including any one of copper, gold, and silver, and a, b, c, d, and e represent the content of each metal in the alloy, b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, e is 0.01 to 0.5 wt%, and a is (100-bcde) wt%.

[0080] In the second process, it is preferable to add copper (Cu), gold (Au), and silver (Ag) in a pure state rather than in an alloy state to prevent any impurities from being contained in the solder ball.

[0081] However, considering the melting points of copper (Cu), gold (Au) and silver (Ag) and the smooth alloying of the pentatonic alloy, it is preferable to carry out the second process with the temperature of the crucible heated to 1100 to 1200°C.

[0083] The present invention will be explained in more detail below through comparative examples and embodiments, but the following embodiments are not intended to limit the scope of the invention and should be interpreted as being for the purpose of aiding understanding of the invention.

[0084] [Examples 1 to 6]: Manufacturing low-melting-point solder balls made of quaternary alloys

[0085] AlGe alloys and InSn alloys or InBi alloys are manufactured, respectively.

[0086] After mixing this at 500 to 700°C, In having the composition of Table 1 a [Sn, Bi] b Al c Ge d The alloy was manufactured.

[0087] In addition, a quaternary alloy was molded using an orifice extrusion method with nitrogen pressure to produce low-melting point solder balls with an average particle size of 50 to 200 μm.

[0088] At this time, a photograph of the quaternary alloy solder ball manufactured according to Example 6 was taken and is shown in Fig. 2.

[0090] [Examples 7 to 9]: Manufacturing a low-melting-point solder ball made of a pentatonic alloy

[0091] AlGe alloys and InSn alloys or InBi alloys are manufactured, respectively.

[0092] After mixing this at 500 to 700°C, In having the composition of Table 1 a [Sn, Bi] b Al c Ge d The alloy was manufactured.

[0093] Next, one of copper (Cu), gold (Au), and silver (Ag) was selected to produce a pentatonic alloy with the composition shown in Table 1.

[0094] In addition, a pentatonic alloy was molded using an orifice extrusion method with nitrogen pressure to produce low-melting point solder balls with an average particle size of 50 to 200 μm.

[0095] At this time, a photograph of the quaternary alloy solder ball manufactured according to Example 7 was taken and is shown in Fig. 3.

[0096] division chemical formula b(wt%) c(wt%) d(wt%) e(wt%) a(wt%) Example 1 InaSnbAlcGed 5 0.7 0.3 - Remaining Example 2 InaSnbAlcGed 5 2.1 0.9 - Remaining Example 3 InaSnbAlcGed 5 3.6 1.4 - Remaining Example 4 InaBibAlcGed 5 0.7 0.3 - Remaining Example 5 InaBibAlcGed 5 2.1 0.9 - Remaining Example 6 InaBibAlcGed 5 3.6 1.4 - Remaining Example 7 InaBibAlcGedCue 5 3.6 1.4 0.1 Remaining Example 8 InaBibAlcGedAue 5 3.6 1.4 0.1 Remaining Example 9 InaBibAlcGedAge 5 3.6 1.4 0.1 Remaining

[0098] [Comparative Example]

[0099] As control groups, a general solder ball, SAC305 (Sn-3Ag-0.5Cu), and a SnBi alloy solder ball (Sn-58Bi, Comparative Example 1) were prepared as comparative examples.

[0101] [Experimental Example] : Evaluation of Physical Properties of Low-Melting Point Solder Balls

[0102] The melting point, hardness, electrical conductivity, and wettability of the alloy-type solder balls prepared according to Examples 1 to 9 above were measured, and the results are shown in Table 2 below.

[0103] In particular, electrical conductivity was measured by fabricating an alloy with a diameter of 10 mm ± 1 mm, contacting it with a contact terminal, and detecting defects through the distribution of eddy currents and changes in the impedance of the test coil, and the results are shown in Figures 4 to 6.

[0104] At this time, FIG. 4 is a graph showing the results of measuring the electrical conductivity of solder balls manufactured according to Comparative Example 1 and Examples 1 to 3, FIG. 5 is a graph showing the results of measuring the electrical conductivity of solder balls manufactured according to Comparative Example 1 and Examples 4 to 6, and FIG. 6 is a graph showing the results of measuring the electrical conductivity of solder balls manufactured according to Comparative Example 1 and Examples 7 to 9.

[0105] Hardness was measured by polishing the manufactured solder ball to create a mirror surface, and then applying a pressure of 0.5 gf to the cross-section of the solder ball with a diamond tip of a Vickers hardness tester and measuring the hardness through the size of the imprinted shape, and the results are shown in FIGS. 7 to 9.

[0106] At this time, FIG. 7 is a graph showing the results of measuring the hardness of solder balls manufactured according to Comparative Example 1 and Examples 1 to 3, FIG. 8 is a graph showing the results of measuring the hardness of solder balls manufactured according to Comparative Example 1 and Examples 4 to 6, and FIG. 9 is a graph showing the results of measuring the hardness of solder balls manufactured according to Comparative Example 1 and Examples 7 to 9.

[0107] The melting point was analyzed by using a TG-DTA to raise the temperature to 1100°C in an N2 atmosphere and measuring the endothermic or exothermic reaction temperature.

[0108] Wetness was evaluated using an swb-2 (manufacturer: Malcolm) instrument. The wave soldering process was replicated exactly, and the wettability characteristics of the components were evaluated in accordance with international standards (JIS, JEITA standards, etc.). The measurement range was +10mN to -10mN, and measurements were taken using a copper tip on molten solder at a temperature of 250℃.

[0109] division Melting point (°C) Hardness (HV / 0.5gf) Electrical conductivity (%IACS) Wetness (mN) Comparative Example 1 217 19.41 3.06 1.99 Example 1 161 3.23 15.84 2.16 Example 2 163.9 10.75 18.25 2.31 Example 3 165.2 23.44 22.14 2.38 Example 4 143 5.15 11.48 - Example 5 146.1 6.02 14.86 - Example 6 146.3 28.93 17.42 - Example 7 146.1 29.57 21.17 - Example 8 146.3 31.51 21.58 - Example 9 146.3 30.73 20.67 2.42

[0110] When comparing the results of the physical property evaluation of the low-melting point solder ball according to the present invention with the results of the physical property evaluation of the control group SnBi solder ball, in terms of melting point, the melting points of Examples 1 to 9 according to the present invention were measured to be 140 to 170°C, which is lower than the melting point of SAC305 (Sn-3Ag-0.5Cu) at 217°C and higher than the melting point of Sn-58Bi at 138°C.

[0111] In addition, regarding hardness, it was confirmed that Comparative Example 1 showed a hardness of 19.41 HV / 0.5 gf, whereas Examples 1 to 9 showed a hardness of 3.0 to 32.0 HV / 0.5 gf, and based on these results, it was confirmed that the hardness increased rapidly as the aluminum (Al) content increased.

[0112] In addition, regarding electrical conductivity, it was confirmed that while the electrical conductivity of Comparative Example 1 was low at 3.06% IACS, the electrical conductivity of Examples 1 to 9 increased to 11.0 to 23.0% IACS.

[0113] In addition, regarding wettability, in the case of Comparative Example 1, the force (Fmax) pulling the molten solder with the copper tip was 1.99 mN and the wetting time T0 was 0.9 s, whereas in the case of Examples 1 to 3 and Example 9, the force (Fmax) pulling the molten solder with the copper tip was 2.16 to 2.42 mN and the wetting time T0 was 0.75 s, confirming that the wettability was superior.

[0114] Through the above Comparative Example 1 and Examples, the suitability of the melting point and excellent hardness, electrical conductivity, and wettability of the low-melting-point solder ball according to the present invention could be confirmed. In addition, compared to conventional solder balls using tin (Sn) as the main component, the low-melting-point solder ball according to the present invention has a relatively lower melting point and excellent wettability, which enables various soldering processes even at low temperatures, and can maintain excellent electrical conductivity and connection between the chip and the package substrate in the result after the soldering process.

[0116] The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the equivalent scope shall be interpreted as being included in the invention.

Claims

Claim 1 A low-melting point solder ball comprising indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge), wherein the content of indium is greater than the content of tin or bismuth, and the alloy is characterized by being represented by the following chemical formula 1. [Chemical Formula 1] In a [Sn, Bi] b Al c Ge d In Chemical Formula 1, [Sn, Bi] means optionally including tin or bismuth, and a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%. Claim 2 delete Claim 3 A low-melting point solder ball according to claim 1, wherein the alloy further comprises any one selected from copper (Cu), gold (Au), and silver (Ag), and is represented by the following chemical formula 2. [Chemical Formula 2] In a [Sn, Bi] b Al c Ge d [Cu, Au, Ag] e In Chemical Formula 2, [Cu, Au, Ag] means optionally including any one of copper, gold, and silver, and a, b, c, d, and e represent the content of each metal in the alloy, b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, e is 0.01 to 0.5 wt%, and a is (100-bcde) wt%. Claim 4 A low-melting point solder ball according to claim 1 or claim 3, characterized in that the average particle size of the solder ball is 50 to 200 μm. Claim 5 A low-melting point solder ball according to claim 1 or claim 3, characterized in that the melting point of the solder ball is 140.0℃ to 170.0℃. Claim 6 A low-melting point solder ball according to claim 1 or claim 3, characterized in that the hardness of the solder ball is 3.0 to 32.0 HV / 0.5gf. Claim 7 A low-melting point solder ball according to claim 1 or claim 3, characterized in that the electrical conductivity of the solder ball is 11.0 to 23.0 %IACS. Claim 8 A low-melting point solder ball according to claim 1 or claim 3, characterized in that the wettability of the solder ball is such that the force (Fmax) of the solder ball pulling the molten solder is 2.0 to 2.5 mN. Claim 9 A low-melting point solder ball according to claim 1 or claim 3, wherein the hardness of the solder ball is 3.23 to 31.51 HV / 0.5gf, the electrical conductivity is 11.48 to 22.14 %IACS, and the wettability is such that the force (Fmax) of the solder ball pulling the molten solder is 2.16 to 2.42 mN. Claim 10 A method for manufacturing a low-melting-point solder ball, comprising: a first step of manufacturing an AlGe alloy and an InBi alloy or an InSn alloy, respectively; a second step of manufacturing an alloy by alloying the AlGe alloy and the InBi alloy or alloying the AlGe alloy and the InSn alloy, wherein the alloy comprises indium (In); tin (Sn) or bismuth (Bi); aluminum (Al); and germanium (Ge), and wherein the content of indium is greater than the content of tin or bismuth; and a third step of forming the alloy manufactured in the second step into a solder ball shape. Claim 11 A method for manufacturing a low-melting point solder ball according to claim 10, characterized in that the alloy manufactured in the first process of the second step is represented by the following chemical formula 1. [Chemical Formula 1] In a [Sn, Bi] b Al c Ge d In Chemical Formula 1, [Sn, Bi] means optionally including tin or bismuth, and a, b, c, and d represent the content of each metal in the alloy, where b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, and a is (100-bcd) wt%. Claim 12 A method for manufacturing a low-melting point solder ball according to claim 11, wherein the second step further comprises, after performing the first process, a second process of adding one selected from copper (Cu), gold (Au), and silver (Ag) to the alloy represented by Chemical Formula 1 and then alloying to produce an alloy represented by Chemical Formula 2 below. [Chemical Formula 2] In a [Sn, Bi] b Al c Ge d [Cu, Au, Ag] e In Chemical Formula 2, [Cu, Au, Ag] means optionally including any one of copper, gold, and silver, and a, b, c, d, and e represent the content of each metal in the alloy, b is 1.0 to 20.0 wt%, c is 0.1 to 5.0 wt%, d is 0.01 to 1.5 wt%, e is 0.01 to 0.5 wt%, and a is (100-bcde) wt%. Claim 13 A method for manufacturing a low-melting point solder ball according to any one of claims 10 to 12, wherein the alloy formed into a solder ball shape in the third step has an average particle size of 50 to 200 μm.

Images