Gold-plated palladium-copper bonding wire and preparation method and application thereof

Abstract

The application relates to a gold-plated palladium-copper bonding wire and a preparation method and application thereof, and relates to the technical field of semiconductor materials. The wire structure of the gold-plated palladium-copper bonding wire comprises, from inside to outside, a copper alloy core material, a palladium plating layer and a gold plating layer; the copper alloy core material contains one or more than two trace alloy elements of Be, P, Ag, Ca and Al; the composition of the copper alloy core material comprises, in terms of weight percentage, Cu >= 99.99 wt%, Be 0.0005-0.005 wt%, P 0.001-0.01 wt%, Ag 0.0005-0.005 wt%, Ca 0.0003-0.002 wt%, Al 0.001-0.01 wt% and inevitable impurities <= 0.001 wt%. The gold-plated palladium-copper bonding wire can be used for BOSB / BBOS ball placement and wire bonding, long wire tail zero false reporting, ball cutting stabilization, mechanical reliability, excellent oxidation resistance and low-cost mass production.

Description

Technical Field

[0001] This invention relates to a gold-plated palladium-copper bonding wire, its preparation method and application, and relates to the field of semiconductor materials technology. Background Technology

[0002] As advanced packaging develops towards high density, fine pitch, and high-speed wire bonding, BOSB / BBOS / SSB ball bonding has become the mainstream process for multi-chip stacking, fan-out, and 2.5D / 3D packaging. This wire bonding method requires first casting bump positioning balls on the chip pads, then cutting the balls to form a stable wire tail platform, and finally bonding the first and second solder joints. This places extremely high demands on FAB molding consistency, HAZ (heat affected zone) toughness, ball cutting plasticity matching, and coating oxidation resistance.

[0003] The existing palladium-plated copper wires generally have the following defects: (1) The annealing process generally adopts high-temperature annealing at 50-100℃ higher than the recrystallization temperature, which leads to excessive growth of the original grains and HAZ grains, resulting in sticking and pulling when cutting the ball, and frequent false alarms of the equipment due to long wire tails; (2) The pure copper matrix has insufficient strength and large plasticity fluctuations, which easily leads to false alarms of NSOL wire breakage or insufficient push-pull force; (3) The single palladium plating layer leads to excessive adhesion between the Pd layer and the frame / bump, resulting in false alarms of post tail; (4) Most patents on the market focus on the plating structure, single element addition or general wire bonding scenarios, and do not carry out a four-in-one collaborative design of "micro-alloy composition-grain control-HAZ toughness-electroplation structure" for the ball cutting characteristics of BOSB / BBOS, which cannot solve the long wire tail problem from the material root.

[0004] Existing technologies only optimize the substrate alloy or a single layer of plating, failing to achieve a three-in-one synergistic design of micro-alloy crystal control, composite plating, and low-temperature semi-annealing. This fails to address the fundamental defects in ball-planting and cutting processes at the material level. Furthermore, existing patent literature reveals several shortcomings: CN104835797B's copper-palladium-silver alloy wire uses a high proportion of Pd and Ag alloying, resulting in extremely high costs and the absence of an ultra-thin gold surface layer, making it unsuitable for ball-planting and cutting; CN105762129B adds a nickel intermediate layer, resulting in a micron-level plating thickness, making delamination easy during fine-diameter wire drawing; CN108198762B has a relatively large plating thickness, leading to high gold consumption; and various existing gold-plated palladium-copper wires lack a grain and annealing system specifically designed for BOSB / BBOS ball-planting applications, resulting in significant shortcomings in high-speed wire planting yield.

[0005] Therefore, there is a significant industrial demand for developing a specialized gold-plated palladium-copper bonding wire that features zero-long-tail alarm during ball-planting, no necking or breakage, stable push-pull force, low cost, and mass production capability. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the present invention aims to provide a gold-plated palladium-copper bonding wire, its preparation method, and its application. The gold-plated palladium-copper bonding wire is a specialized gold-plated palladium-copper bonding wire for BOSB / BBOS ball-mounting and stringing, characterized by zero false alarms at long thread ends, stable ball cutting, reliable mechanical properties, excellent oxidation resistance, and low cost, making it suitable for mass production and meeting significant industrial demand.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a gold-plated palladium-copper bonding wire, wherein the wire structure of the gold-plated palladium-copper bonding wire, from the inside out, consists of a copper alloy core, a palladium plating layer, and a gold plating layer; the copper alloy core contains one or more trace alloying elements selected from Be, P, Ag, Ca, and Al; and by weight percentage, the composition of the copper alloy core includes: Cu ≥ 99.99 wt%, Be 0.0005–0.005 wt%, P 0.001–0.01 wt%, Ag 0.0005–0.005 wt%, Ca 0.0003–0.002 wt%, Al 0.001–0.01 wt%, and unavoidable impurities ≤ 0.001 wt%.

[0008] Preferably, the copper alloy core material comprises, by weight percentage: Cu ≥ 99.99 wt%, Be 0.0012–0.005 wt%, P 0.035–0.005 wt%, Ag 0.008–0.012 wt%, Ca 0.0008–0.002 wt%, Al 0.005–0.01 wt%, and unavoidable impurities ≤ 0.001 wt%.

[0009] The present invention provides a gold-plated palladium-copper bonding wire, which uses microalloying to synergistically control crystal growth of Be, Al, and Ca to refine grains and inhibit abnormal growth of HAZ; P improves the solidification morphology of FAB and enhances the consistency of cut ball residue; Ag enhances conductivity, oxidation resistance and ductility; the gold-plated palladium composite layer blocks Cu diffusion on the one hand and improves bonding wetting and two-weld bonding performance on the other hand.

[0010] In a preferred embodiment of the gold-plated palladium-copper bonding wire of the present invention, the copper alloy core material is a copper matrix, which is prepared by melting 6N high-purity copper as the base material.

[0011] In a preferred embodiment of the gold-plated palladium-copper bonding wire of the present invention, the thickness of the palladium layer is 30–150 nm, the thickness of the gold layer is 2–10 nm, and the total thickness of the palladium layer and the gold layer is 40–160 nm.

[0012] In a preferred embodiment of the gold-plated palladium-copper bonding wire of the present invention, the thickness of the palladium layer is 80-150 nm, the thickness of the gold layer is 3-8 nm, and the total thickness of the palladium layer and the gold layer is 80-160 nm.

[0013] In a preferred embodiment of the gold-plated palladium-copper bonding wire of the present invention, the palladium layer is a weakly alkaline palladium-ammonium system electroplating layer, and the gold layer is a weakly acidic sulfite flash gold plating layer.

[0014] In a preferred embodiment of the gold-plated palladium-copper bonding wire of the present invention, the copper alloy core material has a wire grain size of 0.5-5 μm and a wire diameter of 0.6–2.0 mil.

[0015] On the other hand, the present invention provides a method for preparing the gold-plated palladium-copper bonding wire, comprising the following steps:

[0016] (1) Vacuum melting and continuous casting: 6N high-purity copper is used, microalloying is added, melting is carried out at 1100–1250℃, nitrogen or argon protection is used, and continuous casting is carried out to form Φ6–12mm copper rods.

[0017] (2) Multi-pass reduction drawing: through rough drawing, intermediate drawing, fine drawing and ultra-fine drawing, the pass rate is 6-26%, and the diameter is drawn to 0.6-2.0 mil;

[0018] (3) Activation before electroplating: After degreasing by alkaline washing, activation by acid washing, and then rinsing with water;

[0019] (4) Composite electroplating: First, plate palladium 30–150 nm, then plate gold 2–10 nm;

[0020] (5) Final annealing of finished product: anneal at a temperature 20-40°C higher than the recrystallization temperature for 1-3 seconds, and then cool naturally in an environment of 95% nitrogen and 5% hydrogen to obtain the gold-plated palladium-copper bonding wire.

[0021] (6) Detection of rewinding.

[0022] This invention provides a method for preparing the gold-plated palladium-copper bonding wire, which uses an annealing temperature slightly higher than the recrystallization temperature by 20-40°C. The wire toughness is lower than that of traditional high-temperature annealing, thus avoiding sticking during ball cutting. In addition, the temperature is higher than the recrystallization initiation temperature to eliminate work hardening and eliminate NSOL.

[0023] In a preferred embodiment of the preparation method described in this invention, palladium plating is carried out using a weakly basic palladium-ammonium system at pH 7.0–10, temperature 40–60℃, and current density 10–30 A / dm²; gold plating is carried out using a weakly acidic sulfite gold system at temperature 50–70℃.

[0024] Furthermore, this invention provides the application of the gold-plated palladium-copper bonding wire in the BOSB / BBOS stringing mode. The gold-plated palladium-copper bonding wire is suitable for BOSB, BBOS, and SSB ball-planting stringing modes and can solve the problems of false alarms at the long string tail, unstable ball cutting, and NSOL necking and string breakage.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) This invention provides a special BOSB / BBOS ball bonding wire for gold-plated palladium copper bonding wire, which has zero false alarms at the long end, stable ball cutting, reliable mechanics, excellent oxidation resistance, and low cost and mass production capability. The BOSB / BBOS ball cutting is extremely stable, the false alarms at the long end are reduced to 0, and the yield rate is greatly improved. The strength and toughness are balanced, there is no NSOL necking and breakage, and the push-pull force meets customer standards. The gold-plated palladium composite layer is anti-oxidation and prevents Cu diffusion, and the bonding reliability is high. The low-temperature annealing process is mature, and it can be mass-produced with controllable cost.

[0027] (2) This invention provides a gold-plated palladium-copper bonding wire, which adopts multi-element microalloy synergistic crystal control: Be / Al / Ca pins grain boundaries to inhibit grain growth in the heat-affected zone; P optimizes the spherical shape of molten FAB; Ag simultaneously improves conductivity and oxidation resistance. The multi-element complementarity makes it impossible for a single element to achieve comprehensive balance.

[0028] (3) The present invention provides a method for preparing the gold-plated palladium-copper bonding wire, which adopts a semi-annealing low-temperature process for the gold-plated palladium-copper bonding wire. Compared with the traditional high-temperature annealing of over 50°C, the wire plasticity is moderately reduced, and the molten metal of the ball is less likely to stick to the cleaver, thus eliminating long wires from the root. At the same time, the wire drawing stress is completely released, and NSOL necking is eliminated. The palladium and gold double-layer composite coating, palladium blocks the diffusion of copper oxidation, and ultra-thin gold enhances ultrasonic bonding wetting, reduces the adhesion of palladium to the pad and cleaver, and reduces the fishtail defect of the second solder. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the cross-sectional structure of the gold-plated palladium-copper bonding wire of the present invention, from the inside out: copper alloy core, palladium plating layer, and gold plating layer;

[0030] Figure 2 This is a schematic diagram of the process for ball planting and cutting of the present invention applicable to BOSB / BBOS, wherein, Figure 2 In the middle, A is a gold-plated palladium-copper bonding wire. Figure 2 B in the middle is a FAB molten ball. Figure 2 C is the cutting platform. Figure 2 D in the middle is the tail of the line. Figure 2 E is the first solder joint. Figure 2 F in the middle is the second solder joint.

[0031] Figure 3 This is a schematic diagram of the HAZ grains of the gold-plated palladium-copper bonding wire prepared by low-temperature annealing according to the present invention.

[0032] Figure 4 HAZ grains of gold-plated palladium-copper bonding wire prepared by traditional high-temperature annealing process.

[0033] Figure 5 The validation equipment and devices were performed using the KS Rapid device with a silver-plated frame. Figure 5 A in the middle represents KS equipment; Figure 5 B in the middle is a silver-plated frame; Figure 5 C represents the morphology of the plant; Figure 5 D represents the fishtail morphology of BSOB; Figure 5 The letter E indicates the model number of the splitting blade.

[0034] Figure 6 Verification conditions, ball cutting parameters, experimental parameters: ball cutting mode: FAB size is 1.55mil; Detailed Implementation

[0035] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific drawings and embodiments. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0036] Example 1 This example is a gold-plated palladium-copper bonding wire according to the present invention.

[0037] The gold-plated palladium-copper bonding wire has a wire structure consisting of a copper alloy core, a palladium plating layer, and a gold plating layer from the inside out. The palladium plating layer is 80 nm thick. The outer layer is a gold plating layer of 8 nm. The copper alloy core contains one or more trace alloying elements selected from Be, P, Ag, Ca, and Al2.

[0038] The composition of the copper alloy core material, by weight percentage, includes: high-purity Cu balance, Be 0.0012%, P 0.0035%, Ag 0.0012%, Ca 0.0008%, Al 0.006%, and impurities ≤0.001%.

[0039] This invention provides a method for preparing the gold-plated palladium-copper bonding wire, comprising the following steps:

[0040] (1) Vacuum melting and continuous casting: 6N high-purity copper is used, microalloying is added, melting is carried out at 1150℃, nitrogen protection is applied, and online degassing and refining are performed; continuous casting produces Φ8mm copper rods with uniform grains, no porosity and no inclusions;

[0041] (2) The multi-pass diameter reduction drawing process involves rough drawing, intermediate drawing, fine drawing and ultra-fine drawing in sequence, with the pass processing rate controlled at 26% and the drawing speed gradually increased; the drawing is completed to the target wire diameter of 0.8mil, with a smooth surface and a diameter deviation of ≤±0.2um;

[0042] (3) Electroplating pretreatment activation: The pretreatment activation is carried out in sequence by alkaline washing to remove oil → water washing → acid washing activation → pure water washing; to ensure surface cleanliness and improve the adhesion of the coating.

[0043] (4) Composite electroplating: weak alkaline palladium-ammonium system, pH 10, temperature 60℃, current density 30A / dm², uniform plating speed, dense plating layer without pinholes; gold plating: weak acidic sulfite gold system, temperature 70℃, flash gold coverage, improve bonding wetting and second welding workability; first plating palladium 80nm, then plating gold 8nm.

[0044] (5) Final annealing of finished product: Hold at 400℃ (the recrystallization temperature of the 0.8mil product in this example is 370℃) for 1 second, and cool in a reducing atmosphere of 95% nitrogen and 5% hydrogen; control the grain size to 0.5um, HAZ toughness is moderate, the ball does not stick to the wire, the long wire tail has zero false alarm, and there is no risk of NSOL.

[0045] 6) Detect rewinding.

[0046] The performance results of the gold-plated palladium-copper bonding wire obtained in this embodiment are as follows: breaking force BL: 8.34g; elongation EL: 7.63%; false alarms at the long end: 0 times / 17664 points; the tensile strength at the two solder joints is 6.3g, which meets the customer specifications; NSOL: None.

[0047] Example 2 This example is a gold-plated palladium-copper bonding wire according to the present invention.

[0048] The gold-plated palladium-copper bonding wire has a wire structure consisting of a copper alloy core, a palladium plating layer, and a gold plating layer from the inside out. The palladium plating layer is 100 nm thick. The outer layer is a 5 nm thick gold plating layer. The copper alloy core contains one or more trace alloying elements selected from Be, P, Ag, Ca, and Al.

[0049] The composition of the copper alloy core material, by weight percentage, includes: high-purity Cu balance, Be 0.003%, P 0.005%, Ag 0.0008%, Ca 0.002%, Al 0.005%, and impurities ≤0.001.

[0050] This invention provides a method for preparing the gold-plated palladium-copper bonding wire, comprising the following steps:

[0051] (1) Vacuum melting and continuous casting: 6N high-purity copper is used, microalloying is added, melting is carried out at 1200℃, nitrogen or argon protection is used, and online degassing and refining are performed; continuous casting produces Φ8mm copper rods with uniform grains, no porosity and no inclusions;

[0052] (2) The multi-pass diameter reduction drawing process involves rough drawing, intermediate drawing, fine drawing and ultra-fine drawing in sequence, with the pass processing rate controlled at 6% and the drawing speed gradually increased; the drawing is completed to the target wire diameter of 0.8mil, with a smooth surface and a diameter deviation of ≤±0.2um;

[0053] (3) Electroplating pretreatment activation: The pretreatment activation is carried out in sequence by alkaline washing to remove oil → water washing → acid washing activation → pure water washing; to ensure surface cleanliness and improve the adhesion of the coating.

[0054] (4) Composite electroplating: weak alkaline palladium-ammonium system, pH 7.0, temperature 40℃, current density 10A / dm², uniform plating speed, dense plating layer without pinholes; gold plating: weak acidic sulfite gold system, temperature 50℃, flash gold coverage, improve bonding wetting and second solder workability; first plating palladium 100nm, then plating gold 5nm;

[0055] (5) Final annealing of finished product: Hold at 420℃ (the recrystallization temperature of the 0.8mil product in this example is 380℃) for 1.5s, and cool in a reducing atmosphere of 95% nitrogen and 5% hydrogen; control the grain size to 5um, HAZ toughness to be moderate, ball cutting to be non-sticky, long wire tail to be zero false alarm, and no NSOL risk;

[0056] (6) Detection of rewinding.

[0057] The performance results of the gold-plated palladium-copper bonding wire obtained in this embodiment are as follows: breaking force BL: 8.22g; elongation EL: 7.44%; false alarms at the long end: 0 times / 17664 points; the tensile strength at the two solder joints is 6.22g: meeting customer specifications; NSOL: none.

[0058] Example 3 This example is a gold-plated palladium-copper bonding wire according to the present invention.

[0059] The gold-plated palladium-copper bonding wire has a wire structure consisting of a copper alloy core, a palladium plating layer, and a gold plating layer from the inside out. The palladium plating layer is 150 nm thick. The outer layer is a 10 nm thick gold plating layer. The copper alloy core contains one or more trace alloying elements selected from Be, P, Ag, Ca, and Al.

[0060] The composition of the copper alloy core material, by weight percentage, includes: high-purity Cu balance, Be 0.005%, P 0.01%, Ag 0.005%, Ca 0.002%, Al 0.01%, and impurities ≤0.001%.

[0061] This invention provides a method for preparing the gold-plated palladium-copper bonding wire, comprising the following steps:

[0062] (1) Vacuum melting and continuous casting: 6N high-purity copper is used, microalloying is added, melting is carried out at 1250℃, nitrogen or argon protection is used, and online degassing and refining are performed; continuous casting produces Φ12mm copper rods with uniform grains, no porosity and no inclusions;

[0063] (2) The multi-pass diameter reduction drawing process is carried out in sequence through rough drawing, intermediate drawing, fine drawing and ultra-fine drawing. The pass processing rate is controlled at 15%, and the drawing speed is gradually increased. The wire diameter is drawn to the target wire diameter of 0.8mil, with a smooth surface and a diameter deviation of ≤±0.2um.

[0064] (3) Electroplating pretreatment activation: The pretreatment activation is carried out in sequence by alkaline washing to remove oil → water washing → acid washing activation → pure water washing; to ensure surface cleanliness and improve the adhesion of the coating.

[0065] (4) Composite electroplating: weak alkaline palladium-ammonium system, pH 9, temperature 50℃, current density 20A / dm², uniform plating speed, dense plating layer without pinholes; gold plating: weak acidic sulfite gold system, temperature 60℃, flash gold coverage, improve bonding wetting and second welding workability; first plating palladium 150nm, then plating gold 6nm.

[0066] (5) Final annealing of finished product: Hold at 410℃ (the recrystallization temperature of the product in this embodiment is 390℃) for 3s, and cool in a reducing atmosphere of 95% nitrogen and 5% hydrogen; control the grain size to 0.5um, HAZ toughness is moderate, the ball does not stick to the wire, the long wire tail has zero false alarm, and there is no risk of NSOL.

[0067] (6) Detection of rewinding.

[0068] The performance results of the gold-plated palladium-copper bonding wire obtained in this embodiment are as follows: breaking force BL: 8.14g; elongation EL: 7.18%; false alarms at the long end: 0 times / 17664 points; two-bond tensile strength 6.13g: meets customer specifications; NSOL: none.

[0069] Comparative Example 1: This comparative example is a gold-plated palladium-copper bonding wire.

[0070] The composition of this comparative example is the same as that of Example 1; the preparation method is the same as that of Example 1 except that the final annealing is changed to 480°C.

[0071] Performance results of the gold-plated palladium-copper bonding wire described in Comparative Example 1: Long wire tail false alarm: 28 times / 17664 points; HAZ coarse, ball cutting sticky; push-pull force slightly decreased.

[0072] Comparative Example 2: This comparative example is a gold-plated palladium-copper bonding wire (Comparative Example 2: annealed at 480℃).

[0073] The composition of the comparative example is the same as that of Example 2; the preparation method is the same as that of Example 2 except that the final annealing is changed to 480°C.

[0074] Performance results of the gold-plated palladium-copper bonding wire described in Comparative Example 2: Long wire tail false alarm: 35 times / 17664 points; HAZ coarse, ball cutting sticky; push-pull force slightly decreased.

[0075] Comparative Example 3: This comparative example is a gold-plated palladium-copper bonding wire.

[0076] Compared with Example 1, the substrate of this comparative example is pure Cu, without Be / P / Ag / Ca / Al element doping; the annealing method is the same as in Example 1, and only palladium is plated.

[0077] Performance results of the gold-plated palladium-copper bonding wire described in Comparative Example 3: uneven grain size, large HAZ fluctuation; 14 false alarms at the long end of the wire at 17664 points; poor bonding stability.

[0078] Experimental Example 1: The parameters of Examples 1-3 and Comparative Examples 1-3 are compared, as shown in Table 1.

[0079] Table 1

[0080]

[0081] Comparative Effect Analysis: Examples 1-3 of this invention employ copper substrate alloying, low-temperature annealing, and composite palladium / gold plating. From the WB ball-cutting verification results, no false alarms of ball-cutting NSOL were found. Comparative Examples 1 and 2, using high-temperature annealing, exhibited false alarm frequencies of 1585 ppm and 1981 ppm, respectively. Comparative Example 3, using undoped pure copper, low-temperature annealing, and a single palladium plating method, still showed a false alarm of 792 ppm of ball-cutting NSOL and a false alarm of 226 ppm of Post-tail soldering. This demonstrates that the wire of this invention can effectively improve false alarms of ball-cutting and Post-tail alarms in BOSB / BBOS modes.

[0082] Figure 1 This is a schematic diagram of the cross-sectional structure of the gold-plated palladium-copper bonding wire of the present invention. From the inside out, it consists of a copper alloy core (copper substrate), a palladium plating layer, and a gold plating layer.

[0083] Figure 2 This is a schematic diagram of the process for ball planting and cutting of BOSB / BBOS according to the present invention: FAB melting → FAB pressing down and cutting with a splitter to form a bump ball, leaving a wire tail → the wire continues to be EFO-fired to form FAB and pressed down to form the first bond → the splitter moves up and the wire clamp opens, the wire arcs → the wire is pressed down on the bump ball platform to form a fishtail; wherein, Figure 2 In the middle, A is a gold-plated palladium-copper bonding wire. Figure 2 B in the middle is a FAB molten ball. Figure 2 C is the cutting platform. Figure 2 D in the middle is the tail of the line. Figure 2 E is the first solder joint. Figure 2F in the middle is the second solder joint.

[0084] Figure 3 This is a schematic diagram of the HAZ grains of the gold-plated palladium-copper bonding wire prepared by low-temperature annealing according to the present invention. Figure 4 HAZ grains of gold-plated palladium-copper bonding wire prepared by traditional high-temperature annealing process. Figure 3 and Figure 4 A comparison of HAZ grain sizes of wires at different annealing temperatures shows that after alloying and annealing at 20-40°C above the wire recrystallization temperature, the wire grains of the present invention are small, in a semi-annealed state, with fibrous metallographic phases retained in the middle, corresponding to small HAZ grains after EFO; however, after annealing at 50-100°C above the recrystallization temperature, the wire structure has basically undergone complete recrystallization, corresponding to a coarse HAZ structure after wire EFO.

[0085] Figure 5 The verification equipment and instruments were KS Rapid devices with silver-plated frames, and the verification blade was an SPT model blade.

[0086] Figure 6 The verification conditions were as follows: the cutting parameters and the burning parameters of the FAB ball were 50mA and 320us, and the FAB ball diameter was 1.55mil; the bumping method was stable ball formation, the separation height was 1.2mil, the ball formation height was 0.5mil, and the smoothing distance was 0.2mil.

Claims

1. A gold-plated palladium-copper bonding wire, characterized in that, The gold-plated palladium-copper bonding wire has a wire structure consisting of a copper alloy core, a palladium plating layer, and a gold plating layer from the inside out; the copper alloy core contains one or more trace alloying elements selected from Be, P, Ag, Ca, and Al. The composition of the copper alloy core material, by weight percentage, includes: Cu ≥ 99.99 wt%, Be 0.0005–0.005 wt%, P 0.001–0.01 wt%, Ag 0.0005–0.005 wt%, Ca 0.0003–0.002 wt%, Al 0.001–0.01 wt%, and unavoidable impurities ≤ 0.001 wt%.

2. The gold-plated palladium-copper bonding wire as described in claim 1, characterized in that, The composition of the copper alloy core material, by weight percentage, includes: Cu ≥ 99.99 wt%, Be 0.0012–0.005 wt%, P 0.035–0.005 wt%, Ag 0.008–0.012 wt%, Ca 0.0008–0.002 wt%, Al 0.005–0.01 wt%, and unavoidable impurities ≤ 0.001 wt%.

3. The gold-plated palladium-copper bonding wire as described in claim 1 or 2, characterized in that, The copper alloy core material is a copper matrix, which is prepared by melting 6N high-purity copper as the base material.

4. The gold-plated palladium-copper bonding wire as described in claim 1, characterized in that, The thickness of the palladium plating layer is 30–150 nm, the thickness of the gold plating layer is 2–10 nm, and the total plating thickness of the palladium plating layer and the gold plating layer is 40–160 nm.

5. The gold-plated palladium-copper bonding wire as described in claim 4, characterized in that, The thickness of the palladium plating layer is 80-150 nm, the thickness of the gold plating layer is 3-8 nm, and the total thickness of the palladium plating layer and the gold plating layer is 80-160 nm.

6. The gold-plated palladium-copper bonding wire according to claim 4 or 5, characterized in that, The palladium plating layer is a weakly alkaline palladium-ammonium system electroplating layer, and the gold plating layer is a weakly acidic sulfite flash gold plating layer.

7. The gold-plated palladium-copper bonding wire as described in claim 1, characterized in that, The copper alloy core material has a wire grain size of 0.5-5 μm and a wire diameter of 0.6–2.0 mil.

8. The method for preparing the gold-plated palladium-copper bonding wire according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Vacuum melting and continuous casting: 6N high-purity copper is used, microalloying is added, melting is carried out at 1100–1250℃, nitrogen or argon protection is used, and continuous casting is carried out to form Φ6–12mm copper rods. (2) Multi-pass reduction drawing: through rough drawing, intermediate drawing, fine drawing and ultra-fine drawing, the pass processing rate is 6-26%, and the diameter is drawn to 0.6-2.0 mil; (3) Activation before electroplating: After degreasing by alkaline washing, activation by acid washing, and then rinsing with water; (4) Composite electroplating: First, plate palladium 30–150 nm, then plate gold 2–10 nm; (5) Final annealing of finished product: anneal at a temperature 20-40°C higher than the recrystallization temperature for 1-3 seconds, and then cool naturally in an environment of 95% nitrogen and 5% hydrogen to obtain the gold-plated palladium-copper bonding wire. (6) Detection of rewinding.

9. The preparation method according to claim 8, characterized in that, Palladium plating is performed using a weakly alkaline palladium-ammonium system at pH 7.0–10, temperature 40–60℃, and current density 10–30 A / dm². Gold plating is performed using a weakly acidic sulfite gold system at temperature 50–70℃.

10. The application of the gold-plated palladium-copper bonding wire as described in any one of claims 1–7 in the BOSB / BBOS wire bonding mode, characterized in that, The gold-plated palladium-copper bonding wire is suitable for BOSB, BBOS, and SSB ball-planting stringing modes, and can solve problems such as false alarms at the long string tail, unstable ball cutting, and NSOL necking and string breakage.

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