Bonding wire, method of making the same, and LED device

Abstract

The present application relates to the technical field of packaging materials, and in particular to a bonding wire, a preparation method thereof and an LED device. The bonding wire comprises a core material, and the core material comprises the following components in terms of mass percentage: Cu 5wt%-10wt%, graphene 2wt%-7wt%, Sm 0.25wt%-0.5wt%, Zr 1wt%-1.5wt%, and the balance is Ag. The present application adds Zr elements and graphene to the bonding wire, reasonably controls the content, and cooperates with Cu elements and Sm elements, so that the mechanical properties, corrosion resistance, high-temperature resistance stability, electron migration resistance and reliability of the silver alloy bonding wire are improved; the bonding requirements of the high-power LED device in the complex bonding environment such as low arc formation and high-temperature circulation can be met.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a bonding wire, its preparation method, and an LED device. Background Technology

[0002] Wire bonding is the most common interconnection method in IC packaging. As a key pathway connecting the lead frame of chips, it plays a role in transmitting signals and providing electrical connections. It is one of the essential raw materials in the repackaging and manufacturing processes of integrated circuits, discrete semiconductor devices, and LED light source devices. Bonding wires mainly include gold wire, silver wire, copper wire, and aluminum wire.

[0003] With the increasing prevalence of multi-lead, high integration, and miniaturization in integrated circuits and semiconductor packaging, bonding wires have a growing impact on devices, demanding finer wires with better electrochemical performance for narrow-pitch, long-distance bonding. Compared to alloy bonding wires, which are expensive, copper bonding wires are prone to oxidation and have poor performance, while aluminum wires are primarily used in low-end applications, silver bonding wires are widely used in microelectronic packaging due to their excellent electrothermal properties, ability to reduce high-frequency noise in devices, reduce heat generation in high-power LEDs, good stability, and reasonable cost. However, the application of silver bonding wires often suffers from low bonding strength, unstable performance, poor corrosion resistance and high-temperature stability, and susceptibility to heat-induced failure in high-power devices, severely hindering their development.

[0004] In view of this, this invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a bonding wire with excellent mechanical properties, high-temperature resistance, stability, and reliability.

[0006] The second objective of this invention is to provide a method for preparing bonding wires, which improves the mechanical properties, high-temperature stability, and reliability of the bonding wires.

[0007] A third objective of this invention is to provide an LED device with excellent bonding reliability.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] This invention provides a bonding wire, comprising a core material;

[0010] The core material, by mass percentage, comprises the following components:

[0011] Cu 5wt%–10wt%, graphene 2wt%–7wt%, Sm 0.25wt%–0.5wt%, Zr 1wt%–1.5wt%, balance Ag.

[0012] Furthermore, the mass ratio of Cu to Sm is (19-21):1.

[0013] Furthermore, it includes at least one of the following features (1) to (3);

[0014] (1) The graphene includes monolayer graphene;

[0015] (2) The particle size of the single-layer graphene is 0.1 to 0.5 μm;

[0016] (3) The thickness of the single-layer graphene is <1 nm.

[0017] Furthermore, the bonding wire also includes a protective layer disposed on the surface of the core material;

[0018] And / or, the protective layer includes one or more of Al2O3, ZrO2 and SiO2.

[0019] Furthermore, it includes at least one of the following features (1) to (3);

[0020] (1) The diameter of the bonding wire is 15-25 μm;

[0021] (2) The thickness of the protective layer is 0.3–2 μm;

[0022] (3) The ratio of the thickness of the protective layer to the diameter of the bonding wire is (0.02~0.08):1.

[0023] The present invention also provides a method for preparing the bonding wire as described above, comprising the following steps:

[0024] S1. The Ag / Cu / Sm master alloy is atomized in vacuum to obtain master alloy powder;

[0025] S2. The intermediate alloy powder, Zr powder and graphene powder are mixed and then subjected to molding, vacuum sintering, extrusion and drawing in sequence to obtain wire.

[0026] Furthermore, in step S1, the pressure of the vacuum atomization is 10-12 MPa;

[0027] And / or, the particle size D50 of the intermediate alloy powder is 35-50 μm.

[0028] Furthermore, step S2 includes at least one of the following technical features (1) to (3);

[0029] (1) The molding pressure is 150-200 MPa;

[0030] (2) The vacuum sintering includes sintering at 780-800℃ for 3-5 hours;

[0031] (3) The extrusion temperature is 750-780℃ and the extrusion speed is 4-7mm / s.

[0032] Furthermore, the method for preparing the bonding wire further includes: performing vapor deposition on the surface of the wire to obtain a protective layer;

[0033] And / or, the vapor deposition process further includes a wire drawing process.

[0034] The present invention also provides an LED device, comprising the bonding wire as described above or the bonding wire prepared by the bonding wire preparation method described above.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. The bonding wire of the present invention improves the mechanical properties of the silver alloy bonding wire by optimizing the composition of the silver alloy, adding Zr and graphene to the silver alloy, and combining them with Cu and Sm elements. It has high strength and tensile strength and can be micro-processed; it improves the bonding wire's resistance to electron migration, high temperature resistance and reliability; it can meet the requirements of high-power LED packaging and can be used for bonding high-power LED devices in complex bonding environments such as low arcing and high temperature cycling.

[0037] 2. The bonding wire of the present invention further improves the corrosion resistance of the bonding wire by setting a protective layer on the surface of the silver alloy core material.

[0038] 3. The bonding wire preparation method of the present invention introduces and uniformly distributes high-melting-point graphene in the bonding wire system through atomization powder preparation, molding, vacuum sintering and extrusion processes, thereby successfully preparing bonding wires with excellent performance. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0040] In some embodiments of the present invention, a bonding wire is provided, comprising a core material;

[0041] The core material, by weight percentage, comprises the following components:

[0042] Cu 5wt%–10wt%, graphene 2wt%–7wt%, Sm 0.25wt%–0.5wt%, Zr 1wt%–1.5wt%, balance Ag.

[0043] The bonding wire of the present invention includes a core material, which is a silver alloy. The addition of Zr element in the core material helps to refine the grains and improve the high-temperature stability of the bonding wire. Graphene, as a nano-reinforcing phase, improves the strength of the bonding wire, pins stacking faults and grain boundaries, and can effectively hinder the thermal movement of stacking faults and grain boundaries, thus significantly improving the thermal stability of the bonding wire. The addition of Cu element can increase the ductility and strength of the bonding wire. The addition of Sm element, which can be deposited at grain boundaries, reduces the diffusion effect along the grain boundaries, improves the resistance to electron migration, and improves reliability.

[0044] This invention improves the strength and high-temperature stability of bonding wires by adding Zr and graphene and controlling their content appropriately. At the same time, the combination of Zr and graphene with Cu and Sm elements improves cycling temperature stability, strength, and resistance to electron migration. In summary, the synergistic effect of these elements enhances the basic performance and application reliability of the bonding wires.

[0045] The bonding wire of this invention has excellent mechanical properties, high strength and tensile strength, and can be micro-processed; it has good corrosion resistance, high temperature resistance and anti-electron migration ability; and it can meet the bonding requirements of high-power LED devices in complex bonding environments such as low arcing and high temperature cycling.

[0046] In some embodiments of the present invention, typically but not limitingly, for example, the mass percentage of Cu in the core material can be a range of 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, or any combination thereof; the mass percentage of graphene can be a range of 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, or any combination thereof; the mass percentage of Sm can be a range of 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or any combination thereof; and the mass percentage of Zr can be a range of 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, or any combination thereof.

[0047] In some embodiments of the present invention, the core material, by mass percentage, comprises the following components:

[0048] Cu 6.5wt%–7.5wt%, graphene 4.5wt%–5.5wt%, Sm 0.3wt%–0.4wt%, Zr 1.1wt%–1.3wt%, balance Ag.

[0049] The present invention further optimizes the composition of the core material, and with each component within the above range, a bonding wire with superior performance can be obtained.

[0050] In some embodiments of the present invention, the mass ratio of Cu to Sm is (19-21):1; preferably 20:1. The synergistic effect of Cu and Sm elements is beneficial to improving the strength of the bond line and the stability of the cycling temperature.

[0051] In some embodiments of the present invention, the sum of the mass percentages of Cu and graphene in the core material is 12%. The combination of Cu and graphene is beneficial to improving the strength, high-temperature stability and reliability of the bonding wires.

[0052] In some embodiments of the present invention, graphene includes monolayer graphene.

[0053] In some embodiments of the present invention, the particle size of the monolayer graphene is 0.1 to 0.5 μm.

[0054] In some embodiments of the present invention, the thickness of the single-layer graphene is <1 nm.

[0055] If the graphene particle size is too large, it will deteriorate the mechanical properties of the alloy; if it is too small, it will cause agglomeration during melting and cannot be evenly distributed.

[0056] In some embodiments of the present invention, the bonding wire further includes a protective layer disposed on the surface of the core material.

[0057] In some embodiments of the present invention, the protective layer includes one or more of Al2O3, ZrO2 and SiO2; for example, the protective layer may be an Al2O3 layer, a ZrO2 layer or a SiO2 layer.

[0058] The protective layer of this invention has insulating properties, corrosion resistance, and wear resistance. When used in conjunction with the core material, it can further enhance the strength of the bonding wire.

[0059] In some embodiments of the invention, the diameter of the bonding wire is 15 to 25 μm; typically, but not limitingly, for example, the diameter of the bonding wire can be a range of 15 μm, 20 μm, 25 μm, or any combination thereof.

[0060] In some embodiments of the invention, the thickness of the protective layer is 0.3 to 2 μm; typically, but not limitingly, for example, the thickness of the protective layer is a range of 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, or any combination thereof.

[0061] In some embodiments of the present invention, the ratio of the protective layer thickness to the bonding wire diameter is (0.02 to 0.08):1.

[0062] In some embodiments of the present invention, the breaking force of the bonding wire is 5 to 6 g; preferably 5.5 to 6 g.

[0063] In some embodiments of the present invention, the elongation of the bonding wire is 8% to 9%; preferably 8.5% to 9%.

[0064] In some embodiments of the present invention, the minimum arc height of the bonding wire is less than 80 μm; preferably less than 70 μm.

[0065] In some embodiments of the present invention, a method for preparing the above-mentioned bonding wire is also provided, comprising the following steps:

[0066] S1. The Ag / Cu / Sm master alloy is atomized in vacuum to obtain master alloy powder;

[0067] S2. After mixing the intermediate alloy powder, Zr powder and graphene powder, the mixture is sequentially molded, vacuum sintered, extruded and drawn to obtain wire.

[0068] In the bonding wire preparation method of the present invention, high-melting-point graphene is successfully introduced into the silver alloy system by using atomization powder preparation, molding, vacuum sintering and extrusion processes, and is uniformly distributed in the silver alloy. By utilizing its high strength, high thermal conductivity and ultra-high high temperature stability, the strength, high temperature stability and anti-electron migration ability of the bonding wire are improved.

[0069] In some embodiments of the present invention, step S1, the method for preparing the Ag / Cu / Sm master alloy, includes:

[0070] Ag, Cu, and Sm raw materials were weighed according to the specified ratio and placed in a crucible inside a vacuum furnace. The furnace door was closed and a vacuum of 3 × 10⁻⁶ was drawn. -2 Pa, purging with argon gas to 0.1–0.3 Pa, heating to 600–800 °C, then evacuating to a vacuum of 2 × 10⁻⁶ Pa. - 2Pa, then argon gas is introduced to 0.1-0.3 Pa, and the temperature is raised to 1150-1200℃ for refining for 20-30 min, during which time a magnetic stirring rod is used to stir in the same direction. After furnace cooling, Ag / Cu / Sm master alloy is obtained. Preferably, the purity of Ag, Cu, and Sm raw materials is greater than 99.99%; the crucible includes a high-purity graphite crucible.

[0071] In some embodiments of the present invention, in step S1, the pressure of vacuum atomization is 10-12 MPa.

[0072] In some embodiments of the present invention, in step S1, during the vacuum atomization process, the cooling rate of the molten metal is 100-105°C / s.

[0073] In some embodiments of the present invention, in step S1, the particle size D50 of the intermediate alloy powder is 35-50 μm.

[0074] In some embodiments of the present invention, step S2, mixing includes: weighing the intermediate alloy powder, Zr powder, and graphene powder according to a certain ratio, and then ball milling them; preferably, the ball milling speed is 300-500 r / min; the ball milling time is 5-7 h; and the ball-to-material ratio is 3:1. Preferably, the purity of the Zr powder is ≥99.9%, and the particle size is 35-50 μm.

[0075] In some embodiments of the present invention, in step S2, the molding pressure is 150–200 MPa; preferably, the molding includes: molding the mixture obtained after mixing into a mold with a size of… Pre-pressed in the mold.

[0076] In some embodiments of the present invention, step S2, vacuum sintering includes: sintering at 780–800°C for 3–5 hours; preferably, the vacuum degree of the vacuum sintering process is 2 × 10⁻⁶. -2 Pa.

[0077] In some embodiments of the present invention, in step S2, the extrusion temperature is 750–780°C, and the extrusion speed is 4–7 mm / s; preferably, the size obtained after extrusion is… Bars.

[0078] In some embodiments of the present invention, drawing includes at least two wire drawing processes, and heat treatment is required after each wire drawing process before the next wire drawing process is performed; preferably, drawing includes: performing a first wire drawing process, heat treatment, and a second wire drawing process in sequence.

[0079] In some embodiments of the present invention, in step S2, the extruded rod is subjected to a first drawing process to obtain a rod with a size of [missing information]. The wire diameter is greater than 6mm, and the deformation rate is 12% to 15%. When the diameter is less than 6mm, the deformation rate is controlled at 8% to 10%.

[0080] In some embodiments of the present invention, step S2 includes heat treatment comprising: heat treating the wire obtained after the first drawing process at 400–450°C for 3–5 hours; preferably, the heating rate of the heat treatment is 2–3.5°C / s, and the vacuum degree of the heat treatment process is >10. -2 Pa.

[0081] In some embodiments of the present invention, step S2 includes: performing multiple reduction drawing processes on the heat-treated wire to obtain a wire with a diameter of [missing value]. For wires with a diameter greater than 0.5 mm, the deformation rate is 8%–11%, and the drawing speed is controlled at 7–10 m / s; for wires with a diameter less than 0.5 mm, the deformation rate is 7%–10%, and the drawing speed is 3–5 m / s.

[0082] In some embodiments of the present invention, the method for preparing the bonding wire further includes: performing vapor deposition on the surface of the core material to obtain a protective layer.

[0083] In some embodiments of the present invention, the method for preparing the protective layer includes the following steps:

[0084] The wire obtained after the second drawing process is passed through a continuous vacuum coating equipment, using high-purity Al, Si, or Ti as the target material, and high-purity Ar2 and O2 as the sputtering gas and reaction gas, and magnetron sputtering vacuum coating technology to uniformly sputter a protective layer of 1 to 10 μm on the surface.

[0085] In some embodiments of the present invention, after vapor deposition, a wire drawing process is further included; preferably, the wire after vapor deposition is subjected to a wire drawing process to obtain a bonding wire with a diameter of 15 to 25 μm; the drawing speed of the wire drawing process is 2 to 4 m / s, and the deformation rate is 6% to 8%.

[0086] In some embodiments of the present invention, an LED device is also provided, comprising the bonding wire described above or the bonding wire prepared by the above method.

[0087] The bonding wire of the present invention can meet the requirements of high-power LED packaging and can be used for bonding high-power LED devices in complex bonding environments such as low arc formation and high temperature cycling.

[0088] Example 1

[0089] This embodiment provides a method for preparing bonding wires. The core material composition and content (mass percentage) of the prepared bonding wires are shown in Table 1.

[0090] Table 1

[0091] 1# 5 1 0.25 7 margin 2# 6 1.1 0.3 6 margin 3# 7 1.2 0.35 5 margin 4# 8 1.3 0.4 4 margin 5# 9 1.4 0.45 3 margin 6# 10 1.5 0.5 2 margin

[0092] Specifically, the above-mentioned method for preparing bonding wires includes the following steps:

[0093] S1. Weigh Ag, Cu, and Sm raw materials with a purity greater than 99.99%. According to the proportions, place the weighed raw materials into a high-purity graphite crucible inside a vacuum furnace, close the furnace door, and evacuate to a vacuum level of 3 × 10⁻⁶. -2 Pa, purging with argon gas to 0.1–0.3 Pa, heating to 600–800 °C, then evacuating to a vacuum of 2 × 10⁻⁶ Pa. -2 Pa, then argon gas is introduced to 0.1-0.3 Pa, the temperature is raised to 1150-1200℃, and refined for 20-30 min. During this period, a magnetic stirring rod is used to stir in the same direction. The furnace is cooled to obtain Ag / Cu / Sm master alloy.

[0094] S2. The Ag / Cu / Sm master alloy is atomized in vacuum gas at a pressure of 10–12 MPa and a cooling rate of 100–105 °C / s to obtain master alloy powder with a particle size D50 of 35–50 μm.

[0095] S3. According to the proportions, the weighed intermediate alloy powder, Zr powder (purity 99.9%, particle size 35-50μm) and single-layer graphene powder (particle size D50 0.1-0.5μm, thickness less than 1nm) are ball-milled at a ball-to-material ratio of 3:1, a rotation speed of 300-500r / min, and a ball-milling time of 5-7h to obtain a mixture.

[0096] S4. Mix the materials in It is pressed into shape in a mold at a pressure of 150-200 MPa, and then subjected to a vacuum of 2×10⁻⁶ MPa. -2 Sinter at 780–800℃ for 3–5 hours.

[0097] S5. After sintering, extrusion is performed at a temperature of 750–780℃ and a speed of 4–7 mm / s to obtain the desired dimensions. Bars.

[0098] S6, with dimensions of The rods are drawn into a size by a wire drawing machine. For wires with a diameter greater than 6mm, the deformation rate is 12% to 15%, and for wires with a diameter less than 6mm, the deformation rate is 8% to 10%.

[0099] S7, with dimensions of The wire is placed in a vacuum annealing furnace with a vacuum degree >10. -2Pa, heat to 400-450℃ at a rate of 2-3.5℃ / s for 3-5 hours.

[0100] S8. The heat-treated wire is drawn through a multi-die wire drawing machine in multiple passes to reduce its diameter to the specified dimensions. For wires with a diameter greater than 0.5 mm, the deformation rate is 8% to 11%, and the drawing speed is 7 to 10 m / s. For wires with a diameter less than 0.5 mm, the deformation rate is 7% to 10%, and the drawing speed is 3 to 5 m / s.

[0101] S9, with dimensions of The wire is coated using a continuous vacuum coating equipment, with Si as the target material, using P-shaped single crystal Si, and high-purity Ar2 and O2 as sputtering and reaction gases. Magnetron sputtering vacuum coating technology is used to uniformly sputter a SiO2 protective layer with a thickness of 1 to 10 μm on the surface.

[0102] S10. The magnetron sputtered wire is drawn to a diameter of 15μm using a wire drawing machine at a speed of 2-4m / s and a deformation rate of 6%-8%. Then, it is ultrasonically cleaned for more than 30 minutes and dried with nitrogen. The wire is then wound into a reel and packaged to obtain the bonding wire.

[0103] Comparative Example 1

[0104] This comparative example provides a method for preparing bonding wires. The core material composition and content (mass percentage) of the prepared bonding wires are shown in Table 2.

[0105] Table 2

[0106] 7# 5 1 / 7 margin 8# / 1 0.25 7 margin 9# 5 / 0.25 7 margin 10# 5 1 0.25 / margin

[0107] The method for preparing the bonding wire described above is based on Example 1.

[0108] Experimental Example 1

[0109] The mechanical properties of the bonding wires with a diameter of 15 μm prepared in Example 1 and Comparative Example 1 were tested, and the results are shown in Table 3.

[0110] The testing standards for breaking force and elongation are based on IPC-9702.

[0111] The bonding materials prepared in Example 1 and Comparative Example 1 were used on the Al pads of the memory and tested. The results are shown in Table 3.

[0112] HTST (High Temperature Storage Test): The test conditions are 150℃, and the reference standard is JESD22-A103-A.

[0113] TCT (Temperature Cyclic Aging Test): Test conditions are -55 to 125℃, reference standard JESD22-A104-A.

[0114] Table 3

[0115]

[0116]

[0117] As can be seen from Table 3, compared with Comparative Example 1, the bonding wire of the present invention has higher tensile strength and elongation, and a lower minimum arc height value, resulting in better bonding reliability.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bonding wire, characterized in that, Includes core material; The core material, by mass percentage, comprises the following components: Cu 5wt%~10wt%, graphene 2wt%~7wt%, Sm 0.25wt%~0.5wt%, Zr 1wt%~1.5wt%, balance Ag.

2. The bonding wire according to claim 1, characterized in that, The mass ratio of Cu to Sm is (19~21):

1.

3. The bonding wire according to claim 1, characterized in that, The graphene includes monolayer graphene.

4. The bonding wire according to claim 3, characterized in that, The particle size of the single-layer graphene is 0.1~0.5μm.

5. The bonding wire according to claim 3, characterized in that, The thickness of the single-layer graphene is <1 nm.

6. The bonding wire according to claim 1, characterized in that, The bonding wire also includes a protective layer disposed on the surface of the core material.

7. The bonding wire according to claim 6, characterized in that, The protective layer includes one or more of Al2O3, ZrO2 and SiO2.

8. The bonding wire according to claim 6, characterized in that, Includes at least one of the following features (1) to (3); (1) The diameter of the bonding wire is 15~25μm; (2) The thickness of the protective layer is 0.3~2μm; (3) The ratio of the thickness of the protective layer to the diameter of the bonding wire is (0.02~0.08):

1.

9. The method for preparing bonding wires according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. The Ag / Cu / Sm master alloy is atomized in vacuum to obtain master alloy powder; S2. The intermediate alloy powder, Zr powder and graphene powder are mixed and then subjected to molding, vacuum sintering, extrusion and drawing in sequence to obtain wire.

10. The method for preparing bonding wire according to claim 9, characterized in that, In step S1, the pressure of the vacuum atomization is 10~12MPa; And / or, the particle size D50 of the intermediate alloy powder is 35~50μm.

11. The method for preparing bonding wire according to claim 9, characterized in that, Step S2 includes at least one of the following technical features (1) to (3); (1) The molding pressure is 150~200MPa; (2) The vacuum sintering includes: sintering at 780~800℃ for 3~5h; (3) The extrusion temperature is 750~780℃ and the extrusion speed is 4~7mm / s.

12. The method for preparing bonding wire according to claim 9, characterized in that, Also includes: A protective layer is obtained by vapor deposition on the surface of the wire.

13. The method for preparing bonding wire according to claim 12, characterized in that, The vapor deposition process also includes a wire drawing process.

14. An LED device, characterized in that, The bonding wires include those prepared by the bonding wire preparation method according to any one of claims 1 to 8 or claims 9 to 13.

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