High-reliability ball bonding gold wire and preparation method

Abstract

The high-reliability ball bonding gold wire is prepared from the following raw materials in parts by weight: 2 to 10 ppm of Be, 0 to 30 ppm of Ca, 5 to 20 ppm of Pd, 5 to 20 ppm of Pt, 5 to 20 ppm of Al, 0 to 20 ppm of Mg, 5 to 30 ppm of Ce, 0 to 20 ppm of La, 0 to 30 ppm of Y, 0 to 30 ppm of Gd, 2 to 30 ppm of Bi, less than or equal to 100 ppm of added total content and the balance of Au with the purity of 99.999 wt%. The raw materials are sequentially subjected to vacuum melting, hot extrusion, rolling, intermediate annealing, intermediate-fine-fine drawing and annealing to prepare the alloy. The gold wire prepared by optimizing the content of the alloy elements is good in grain size, uniform in salient point grain and stable in length of a heat affected zone, the coplane consistency of gold salient points during ball bonding can be improved, and the gold wire has high strength and high reliability.

Description

TECHNICAL FIELD

[0001] The application relates to a high-reliability ball-welding gold wire and a preparation method thereof, and belongs to the technical field of bonding wire processing. BACKGROUND

[0002] Electronic assembly needs to establish electrical connection between chips and substrates, chips and chips, and the parasitic capacitance and inductance of long lead wires of lead bonding as the most traditional bonding mode are large, and the limitation of large required space has been difficult to meet the development demand of miniaturization, thinness, intelligence and high reliability of electronic products. Unlike the lead bonding mode, flip-chip welding can realize electrical connection between chips and the outside without using metal core wires, shorten the interconnection distance, and realize miniaturized packaging. Flip-chip welding adopts bump connection, reduces the interconnection distance between chips and substrates, thereby reducing resistance and inductance, improving signal transmission speed and integrity, and meanwhile, the bump connection improves the I / O terminal connection density and realizes more functional integration. In addition, the chip front surface is in contact with the substrate, which provides a more direct conduction path for heat and enhances the heat dissipation function, thereby improving the electrical performance, which makes flip-chip welding become the most promising chip interconnection technology.

[0003] Traditional flip-chip packaging adopts lead-containing solder bumps to realize interconnection, and lead-tin solder bumps are most commonly used. With the implementation of the advocacy of green manufacturing, lead-free solder has replaced lead-containing solder, but the existing lead-free solder has poor conductivity and heat conductivity. The advantages of gold material in conductivity and thermal conductivity make the gold bump interconnection technology gradually become a better solution for flip-chip packaging. The gold bump interconnection not only has a short process, but also can provide a clean and pollution-free interface, avoids pollution of the device caused by flux, and improves the reliability of bonding; and the gold bump reduces the problem of mismatch of the coefficient of thermal expansion, and reduces the aging failure caused by long-term use.

[0004] The addition of 1% Pd in the existing 2N gold wire can make the shape of the bump easy to control, and the height consistency of the bump tail is good, but the required pressure is large during the production of the bump, which leads to poor consistency of the coplanarity of the bump during the ball welding process, and the chip welding area is easily damaged, especially some chips with special structure and sensitive to pressure are more likely to be damaged; the existing 4N gold wire has good weldability, can still maintain a large welding window under a lower pressure degree, and avoids damage to the chip, but the bonding strength is insufficient, and the reliability is reduced.

[0005] Therefore, the application provides a high-reliability ball-welding gold wire and a preparation method thereof, which are prepared by improving the component formula and the preparation method, and guaranteeing high purity (99.99wt%) of the bonding gold wire. SUMMARY

[0006] At least for one problem of the prior art, the application provides a high-reliability ball-welding gold wire and a preparation method thereof, the gold wire with a purity of 99.99% is prepared by optimizing the content of alloying elements and adopting a melting-hot extrusion-rolling method, the prepared gold wire has good grain size, uniform bump grain, and stable heat-affected zone length, and can improve the consistency of the gold bump coplanar during ball welding, and has high strength and high reliability.

[0007] To achieve the above object, the application adopts the following technical scheme: a high-reliability ball-welding gold wire, comprising the following raw materials and weight parts: beryllium (Be) 2-10 ppm, calcium (Ca) 0-30 ppm, palladium (Pd) 5-20 ppm, platinum (Pt) 5-20 ppm, aluminum (Al) 5-20 ppm, magnesium (Mg) 0-20 ppm, cerium (Ce) 5-30 ppm, lanthanum (La) 0-20 ppm, yttrium (Y) 0-30 ppm, gadolinium (Gd) 0-30 ppm, and bismuth (Bi) 2-30 ppm, and the total content of the added amounts is ≤100 ppm, and the rest is gold (Au) with a purity of 99.999 wt%.

[0008] Preferably, the high-reliability ball-welding gold wire is prepared by sequentially subjecting the raw material composition to vacuum melting, hot extrusion, rolling, intermediate annealing, medium-fine-micro drawing, and annealing.

[0009] Preferably, the high-reliability ball-welding gold wire comprises the following raw materials and weight parts: Be 6 ppm, Pd 10 ppm, Pt 15 ppm, Al 10 ppm, cerium Ce 18 ppm, Gd 5 ppm, and Bi 8 ppm, and the rest is Au with a purity of 99.999 wt%.

[0010] The application further provides a preparation method of the high-reliability ball-welding gold wire, comprising the following steps: S1, preparation of a gold ingot with uniform components: according to the target weight of the above raw materials, doping elements and gold elements are subjected to vacuum melting to form a gold ingot with uniform components; S2, hot extrusion to prepare a coarse gold rod: the gold ingot with uniform components in step S1 is subjected to hot extrusion to prepare a coarse gold rod with dense organization and small grain size; S3, rolling to prepare a fine gold rod: the coarse gold rod in step S2 is subjected to rolling to further refine the grain to form a fine gold rod; S4, intermediate annealing treatment of the fine gold rod: the fine gold rod in step S3 is subjected to intermediate annealing to form a fine gold rod with better organization consistency; S5, medium-fine-micro drawing to prepare a gold wire: the fine gold rod in step S4 is sequentially subjected to medium drawing, fine drawing, and micro drawing to form a gold wire; S6, annealing treatment of the gold wire: the gold wire in step S5 is subjected to annealing to obtain a gold wire product.

[0011] Preferably, a high-reliability ball-welding gold wire preparation method, the specific preparation process is as follows: S1, preparation of gold ingot with uniform composition S1.1, material preparation: gold particle purity 99.999wt%, palladium particle purity 99.95wt%, platinum particle purity 99.95wt%, beryllium particle purity 99.95wt%, calcium particle purity 99.95wt%, aluminum particle purity 99.99wt%, magnesium particle purity 99.95wt%, cerium particle purity 99.5wt%, yttrium particle purity 99.9wt%, lanthanum particle purity 99.9wt%, gadolinium particle purity 99.9wt% and bismuth particle purity 99.9wt%; S1.2, gold ingot refining: using a medium-frequency induction melting furnace, refining under vacuum conditions to remove non-gas elements, and casting into a hollow gold sleeve; S1.3, melting of master alloy: according to the target weight, weighing high-purity gold raw materials with a weight ratio of 99.20~99.60wt% (purity 99.999wt%) and adding elements with a weight ratio of 0.40~0.80wt%, to prepare Au-Pt-Pd, Au-Be, Au-Ca, Au-Al, Au-Mg, Au-Ce, Au-Y, Au-La, Au-Bi and Au-Gd master alloys, during melting of each master alloy, the adding elements are placed in the hollow gold sleeve and then placed in a crucible for vacuum refining, after melting, stirring 30~50 times, standing for 5~30min, casting into ingots, repeating the ingot casting 2~3 times to form different master alloy ingots for standby; S1.4, vacuum melting: weighing each master alloy according to the content of the doping elements, the total content of the doping elements ≤100ppm, the balance of gold ≥99.99wt%, placing the master alloy into the hollow gold sleeve and then into the crucible for vacuum refining, after melting of the material, stirring 20~50 times, standing for 5~30min, casting into ingots, repeating the ingot casting 2~3 times to obtain gold ingots with uniform composition; S2, hot extrusion to prepare a rough gold rod: Hot extrusion: using a hot extruder to heat and hot extrude the gold ingot with uniform composition of step S1.4, directly reducing the diameter of the gold ingot to 9~11mm to obtain a rough gold rod with dense structure, small grain size and excellent performance; S3, rolling to prepare a fine gold rod: Rolling: rolling the rough gold rod of step S2 to 1.54~1.56mm to continue to refine the grain size, obtain a fine gold rod, improve the toughness, save the large drawing and improve the work efficiency; S4, intermediate annealing treatment of the fine gold rod: Intermediate annealing: annealing the fine gold bar of step S3 above at 200-500℃ for 2-4h, cooling with furnace, after annealing, the 1.54-1.6mm gold bar has better consistency of grain structure, and the ball is more round and has better consistency when bonding; S5, medium-fine-micro drawing gold wire: S5.1, first medium drawing treatment of the fine gold bar of step S4: changing diameter from 1.54-1.56mm to 0.2mm, reduction rate 13%, drawing liquid temperature 30-35℃, drawing speed 60-100m / min; S5.2, then fine drawing treatment: changing diameter from 0.2mm to 0.07mm, reduction rate 13%, drawing liquid temperature 30-35℃, drawing speed 200-250m / min; S5.3, finally micro drawing treatment: changing diameter from 0.07mm to target diameter, reduction rate 13%, drawing liquid temperature 30-35℃, drawing speed 300-400m / min; S6, gold wire annealing treatment: Finished product annealing: annealing the gold wire of step S5 above using a tube furnace, annealing temperature 400-600℃, annealing speed 30-50m / min.

[0012] Preferably, in step S2, the heating condition of hot extrusion: mold preheating 400-600℃, gold ingot heating temperature 500-700℃, holding time 1-2h.

[0013] Preferably, in step S2, the hot extrusion condition of hot extrusion: hot extrusion speed 10-20mm / s; After extrusion, the rod is cooled in pure water, cooling water temperature <30℃, pure water conductivity ≥3.0MΩ·cm.

[0014] Preferably, in step S3, the rolling is continuous cold rolling; the rolling mode is not limited to two-roll, three-roll or multi-roll.

[0015] Preferably, in step S3, the deformation of each pass of the rolling is 5-20%.

[0016] Preferably, in step S5.3, the target diameter of the gold wire is 15-50μm.

[0017] Preferably, in step S1.2, the condition of the gold ingot refining: vacuum degree 1×10 -3 Pa, refining power 16-24kw, refining time 1-2h.

[0018] Preferably, in steps S1.3 and S1.4, the condition of the gold ingot refining: vacuum degree 1×10 -3Pa, refining power 16~24kw, melting temperature 1200~1400℃, refining time 1~2h.

[0019] Preferably, in step S1.2, the size of the hollow gold sleeve is 10-50 mm in inner diameter, 15-55 mm in outer diameter, 2-5 mm in thickness and 50-100 mm in height.

[0020] Preferably, in step S1.4, the size of the gold ingots is 50-90 mm in diameter and 20-100 mm in height.

[0021] Preferably, the process further comprises rewinding and packaging: the finished gold wire of S6 is rewound onto a finished product bobbin according to a required length, and the bobbin box is sealed and packaged.

[0022] Beneficial effects of the present invention: 1. The high-reliability ball bonding gold wire of the present invention is produced by selecting different doping elements, optimizing the content of alloy elements, and undergoing smelting, hot extrusion, rolling, intermediate annealing, medium-fine-micro drawing and other process steps. The gold wire has good grain size, uniform bump grains, and stable heat-affected zone length, thereby improving the consistency of the coplanarity of the gold bumps during ball bonding and being able to control the height difference of the gold bumps on the entire chip to ±5μm.

[0023] 2. The high-reliability ball-bonding gold wire of the present invention has high strength and high reliability, and can meet the requirements of product miniaturization and high density.

[0024] 3. The preparation method of the high-reliability ball solder gold wire of the present invention adopts a melting-hot extrusion-rolling method, which replaces the traditional continuous casting-wire drawing process, which not only simplifies the process flow and improves production efficiency, but also improves the organizational structure of the gold wire.

[0025] 4. The method for preparing the high-reliability ball-bonding gold wire of the present invention effectively improves the grain size inside the bar through hot extrusion and rolling, thereby greatly improving the strength and elongation of the wire.

[0026] 5. The method for preparing the high-reliability ball solder gold wire of the present invention also uses vacuum melting and rapid casting and cooling, which improves the uneven distribution of doped elements in the traditional continuous casting process and improves the stability of the wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the grains of Example 1 of the present invention.

[0028] Figure 2 This is a scanning electron image of the grains of Comparative Example 1 of the present invention.

[0029] Figure 3 This is the IMC growth trend diagram of the present invention. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present application. The described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used.

[0031] Embodiment 1 A high-reliability ball-welding gold wire comprises the following raw materials and their weight parts: Be 5ppm, Ca 10ppm, Pd 10ppm, Pt 10ppm, Al 10ppm, Mg 10ppm, Ce 10ppm, La 10ppm, Y 10ppm, Gd 10ppm and Bi 5ppm, and the rest is Au with a purity of 99.999wt%; The specific preparation method of the high-reliability ball-welding gold wire is as follows: S1, preparation of a gold ingot with uniform components S1.1, preparation of materials: gold particles with a purity of 99.999wt%, palladium particles with a purity of 99.95wt%, platinum particles with a purity of 99.95wt%, beryllium particles with a purity of 99.95wt%, calcium particles with a purity of 99.95wt%, aluminum particles with a purity of 99.99wt%, magnesium particles with a purity of 99.95wt%, cerium particles with a purity of 99.5wt%, yttrium particles with a purity of 99.9wt%, lanthanum particles with a purity of 99.9wt%, gadolinium particles with a purity of 99.9wt% and bismuth particles with a purity of 99.9wt%; S1.2, refining of the gold ingot: using a medium-frequency induction melting furnace, refining for 2h under a vacuum degree of 1×10 -3 Pa, power 20kw, removing non-gas elements, and casting into a hollow gold sleeve with an inner diameter of 10mm, an outer diameter of 20mm, a thickness of 2mm and a height of 100mm; S1.3, melting of the master alloy: according to the target weight, weighing high-purity gold raw materials (purity 99.999wt%) with a weight ratio of 99.20~99.60wt%, and adding elements with a weight ratio of 0.40~0.80wt%, to prepare Au-Pt-Pd, Au-Be, Au-Ca, Au-Al, Au-Mg, Au-Ce, Au-Y, Au-La, Au-Bi and Au-Gd master alloys, and when melting each master alloy, the adding elements are put into the hollow gold sleeve, into the crucible and under a vacuum degree of 1×10 -3Vacuum refining is carried out at 1200°C for 2 hours at a power of 20 kW and a temperature of 1200°C. The smelting method is to add elements into a hollow gold sleeve and then place it into a crucible to ensure that the composition of the melt is consistent on each horizontal surface. After melting, stir 30 times, let it stand for 5 minutes, and cast it into ingots. Repeat the casting process 2 to 3 times to form different master alloy ingots for use. S1.4, vacuum melting: weigh the master alloy ingots according to the doping element content, the total content of doping elements ≤ 100ppm, the balance gold ≥ 99.99 wt% and put the master alloy into a hollow gold sleeve, and then put it into a crucible and place it in a vacuum of 1×10 -3 Vacuum refining is carried out at a pressure of 2400 Pa, a power of 24 kW, and a temperature of 1300°C for 1 to 2 hours. The smelting method is to place the master alloy into a hollow gold sleeve and then into a crucible to ensure that the composition of the melt is consistent on each horizontal surface. After the material is melted, it is stirred 50 times and allowed to stand for 10 minutes before being cast into an ingot. The ingot casting is repeated 2 to 3 times to obtain a gold ingot with a uniform composition and a diameter of 90 mm and a height of 80 mm; S2. Preparation of rough gold rods by hot extrusion: Hot extrusion: The gold ingot with uniform composition obtained in step S1.4 is heated using a hot extruder. Heating conditions include: mold preheating at 500°C, gold ingot heating temperature at 700°C, argon protection, and holding time of 1 hour. Hot extrusion is then started. Hot extrusion conditions include: hot extrusion speed of 10 mm / s, and the gold ingot is directly reduced to 10 mm in diameter. After extrusion, the bar is cooled in pure water. The cooling water temperature is <30°C, and the pure water conductivity is ≥3.0 MΩ·cm. A coarse gold bar with dense structure, fine grains, and excellent performance is obtained. S3. Rolling to prepare thin gold bars: Rolling: The rough gold bar from step S2 is rolled through continuous cold rolling, using a multi-roll rolling mill to reduce the 10 mm rough gold bar to 1.55 mm, with a deformation of 5% per pass, to further refine the grains and obtain fine gold bars, thereby increasing toughness, eliminating the need for large-scale drawing, and improving work efficiency. S4, intermediate annealing treatment of thin gold rods: Intermediate annealing: anneal the thin gold rod in step S3 at 300℃ for 4h and cool it in the furnace. After annealing, the 1.55mm thin gold rod is Figure 1 As shown, the gold particles have better consistency, and the balls are more rounded and have good consistency when bonding; S5, medium-fine-micro-drawing gold wire preparation: S5.1. The thin gold rod prepared in step S4 is first subjected to intermediate drawing: the diameter is reduced from 1.55 mm to 0.2 mm, the surface reduction rate is 13%, the drawing liquid temperature is 30°C, and the drawing speed is 60 m / min; S5.2, then fine drawing treatment: diameter reduction from 0.2mm to 0.07mm, surface reduction rate 13%, drawing liquid temperature 30℃, drawing speed 200m / min; S5.3, final micro-drawing: from 0.07 mm to target diameter: 18 μm, 20 μm, 23 μm, 25 μm, 30 μm, 35 μm and 40 μm, reduction 13%, drawing liquid temperature 30°C, drawing speed 400 m / min; S6, gold wire annealing treatment: Finished product annealing: the gold wire of step S5 above is annealed using a tube furnace, annealing temperature 500°C, annealing speed 30 m / min; S7, rewinding and packaging: the finished product gold wire of S6 above is rewound on a finished product spool according to the required length, and the spool box is sealed and packaged.

[0032] Example 2 A high-reliability ball-welding gold wire, comprising the following raw materials and their weight parts: Be 5 ppm, Ca 15 ppm, Pd 10 ppm, Pt 10 ppm, Al 5 ppm, Mg 5 ppm, Ce 10 ppm, La 10 ppm, Y 10 ppm, Gd 10 ppm and Bi 10 ppm, the rest being Au with a purity of 99.999 wt%; The difference between the preparation steps of the high-reliability ball-welding gold wire and Example 1 is that: S5.1, first intermediate-drawing of the thin gold rod of step S4: from 1.55 mm to 0.2 mm, reduction 13%, drawing liquid temperature 30°C, drawing speed 80 m / min; S5.2, then fine-drawing: from 0.2 mm to 0.07 mm, reduction 13%, drawing liquid temperature 30°C, drawing speed 240 m / min; S5.3, final micro-drawing: from 0.07 mm to target diameter: 18 μm, 20 μm, 23 μm, 25 μm, 30 μm, 35 μm and 40 μm, reduction 13%, drawing liquid temperature 30°C, drawing speed 350 m / min.

[0033] Example 3 A high-reliability ball-welding gold wire, comprising the following raw materials and their weight parts: Be 5 ppm, Ca 10 ppm, Pd 10 ppm, Pt 10 ppm, Al 5 ppm, Mg 5 ppm, Ce 10 ppm, La 10 ppm, Y 5 ppm, Gd 10 ppm and Bi 20 ppm, the rest being Au with a purity of 99.999 wt%; The difference between the preparation steps of the high-reliability ball-welding gold wire and Example 1 is that: S5.1, first intermediate-drawing of the thin gold rod of step S4: from 1.55 mm to 0.2 mm, reduction 13%, drawing liquid temperature 30°C, drawing speed 100 m / min; S5.2, then fine drawing treatment: diameter reduction from 0.2mm to 0.07mm, surface reduction rate 13%, drawing liquid temperature 30℃, drawing speed 200m / min; S5.3. Finally, the wire was micro-drawn: the diameter was changed from 0.07 mm to the target diameters of 18 μm, 20 μm, 23 μm, 25 μm, 30 μm, 35 μm and 40 μm, the surface reduction rate was 13%, the drawing liquid temperature was 30 ° C, and the drawing speed was 300 m / min.

[0034] Example 4 A high-reliability ball bonding gold wire comprises the following raw materials and their weight percentages: Be 6ppm, Pd 10ppm, Pt 15ppm, Al 10ppm, Cerium Ce 18ppm, Gd 5ppm, and Bi 8ppm, with the remainder being 99.999wt% pure Au; The specific preparation method of the high reliability ball bonding gold wire is as follows: S1. Preparation of gold ingots with uniform composition S1.1. Prepare materials: gold particles with a purity of 99.999wt%, palladium particles with a purity of 99.95wt%, platinum particles with a purity of 99.95wt%, beryllium particles with a purity of 99.95wt%, aluminum particles with a purity of 99.99wt%, cerium particles with a purity of 99.5wt%, gadolinium particles with a purity of 99.9wt%, and bismuth particles with a purity of 99.9wt%. S1.2 Gold ingot refining: Use medium frequency induction melting furnace, vacuum degree 1×10 -3 Pa, refining power 16~24kw under vacuum conditions for 1~2h to remove non-gaseous elements, and then cast into a hollow gold sleeve with an inner diameter of 10~50mm, an outer diameter of 15~55mm, a thickness of 2~5mm and a height of 50~100mm; S1.3, Melting of Master Alloys: According to the target weight, weigh 99.20~99.60wt% of high-purity gold raw materials (purity 99.999wt%) and 0.40~0.80wt% of additive elements to prepare Au-Pt-Pd, Au-Be, Au-Al, Au-Ce and Au-Gd master alloys. When melting each master alloy, add the additive elements into a hollow gold sleeve, put it into a crucible and place it under vacuum at 1×10 -3 Vacuum refining is carried out at 1200°C for 2 hours at a power of 16 kW and a temperature of 1200°C. The smelting method is to add elements into a hollow gold sleeve and then place it into a crucible to ensure that the composition of the melt is consistent on each horizontal surface. After melting, stir 40 times, let it stand for 15 minutes, and cast it into ingots. Repeat the casting process 2 to 3 times to form different master alloy ingots for use. S1.4, vacuum melting: the master alloy ingot is weighed according to the content of the doping element, the total content of the doping element is ≤100ppm, and the balance of gold is ≥99.99 wt% for feeding, the master alloy is placed in a hollow gold sleeve, then placed in a crucible, and the vacuum degree is 1x10 -3 Pa, power 20kw, temperature 1200℃, vacuum refining for 2h, the melting method is that the master alloy is placed in a hollow gold sleeve and then placed in a crucible, which can ensure that the composition on each horizontal plane of the molten liquid is consistent, after the material is melted, stirring for 20 times, and standing for 25min, casting into ingots, repeating the casting of ingots for 2-3 times, and obtaining gold ingots with uniform composition, size of 90mm in diameter and 100mm in height; S2, hot extrusion to prepare a rough gold bar: Hot extrusion: the gold ingot with uniform composition in step S1.4 is heated and hot extruded using a hot extruder, the gold ingot is directly reduced in diameter to 10mm, the heating conditions are that the mold is preheated to 400℃, the gold ingot is heated to 500℃, and the holding time is 2h, the hot extrusion conditions are that the hot extrusion speed is 20mm / s, after extrusion, the rod is cooled in pure water, the cooling water temperature is <30℃, the conductivity of the pure water is ≥3.0MΩ·cm, and a rough gold bar with dense structure, small grains and excellent performance is obtained; S3, rolling to prepare a fine gold bar: Rolling: the rough gold bar in step S2 is rolled by continuous cold rolling, a multi-roll rolling machine is used to roll the 10mm rough gold bar to 1.55mm, and the deformation amount of each pass is 8%, the crystal grains are continuously refined, a fine gold bar is obtained, the toughness is improved, the large drawing is omitted, and the working efficiency is improved; S4, intermediate annealing treatment of the fine gold bar: Intermediate annealing: the fine gold bar in step S3 is annealed at 500℃ for 2h and cooled in the furnace, after annealing of the 1.55mm gold bar, the gold grain structure is more consistent, the ball is more round during bonding, and the consistency is good; S5, drawing of the fine gold bar to prepare a gold wire: S5.1, the fine gold bar in step S4 is first subjected to intermediate drawing: the diameter is changed from 1.55mm to 0.2mm, the area reduction rate is 13%, the wire drawing liquid temperature is 35℃, and the wire drawing speed is 70m / min; S5.2, then subjected to fine drawing: the diameter is changed from 0.2mm to 0.07mm, the area reduction rate is 13%, the wire drawing liquid temperature is 35℃, and the wire drawing speed is 220m / min; S5.3, finally subjected to micro drawing: the diameter is changed from 0.07mm to 0.025mm, the area reduction rate is 13%, the wire drawing liquid temperature is 35℃, and the wire drawing speed is 380m / min; S6, annealing treatment of the gold wire: Finished product annealing: the gold wire in step S5 is annealed using a tube furnace, the annealing temperature is 400℃, and the annealing speed is 40m / min; S7, rewinding packaging: rewinding the gold wire product of S6 above on a product spool according to the required length, and sealing and packaging the spool box.

[0035] Comparative Example 1 A high-reliability ball-welding gold wire, which is different from Example 1 in that the added amount of Bi in the raw material composition is 0 ppm; as shown in the grain scanning diagram after annealing. Figure 2

[0036] By Figure 1 and Figure 2 It is found by comparison that, by doping an appropriate amount of bismuth element, the grain size of Example 1 is refined, the size is reduced, the ball roundness is good after balling, and the gold grain organization is more consistent.

[0037] Comparative Example 2 A high-reliability ball-welding gold wire, which comprises the following raw materials and the same weight parts as Example 1; The specific preparation method of the high-reliability ball-welding gold wire is different from that of Example 1: S1, preparation of a master alloy with uniform components S1.1, preparation of materials: gold grain purity 99.999wt%, palladium grain purity 99.95wt%, platinum grain 99.95wt%, beryllium grain purity 99.95wt%, calcium grain purity 99.95wt%, aluminum grain purity 99.99wt%, magnesium grain purity 99.95wt%, cerium grain purity 99.5wt%, yttrium grain purity 99.9wt%, lanthanum grain purity 99.9wt%, gadolinium grain purity 99.9wt% and bismuth grain purity 99.9wt%; S1.2, smelting of the master alloy: high-frequency furnace smelting, vacuum protection, vacuum degree 0.1*10-3Pa, smelting temperature 1250℃, multiple stirring, to obtain a master alloy with uniform composition; S2, casting gold bar: using a vertical continuous casting furnace, adding trace amounts of alloying elements less than 100 ppm to gold with a purity of 99.999wt% to draw a 99.99wt% gold bar with a diameter of 8mm at a speed of 60mm / min and an argon gas pressure of 0.01~0.05Pa; S3, rough drawing: rough drawing of the continuously cast gold bar, rough drawing die elongation 15%, drawing speed 15m / min, to draw a 1.55mm fine gold bar; and then sequentially performing S4 of Example 1, intermediate annealing treatment of the fine gold bar, S5, preparation of gold wire by medium-fine-micro drawing, S6, gold wire annealing treatment and S7, rewinding packaging.

[0038] Comparative Example 3 A high-reliability ball-welding gold wire, which comprises the following raw materials and the same weight parts as Example 1; ​The specific preparation method of the high-reliability ball-welding gold wire is different from that of Example 1, and the difference is that the S5, the medium-thin-ultra-thin drawing of the gold wire is prepared: S5.1, the medium drawing of the thin gold rod of step S4 is performed at a die elongation of 15%, the diameter is changed from 1.55 mm to 0.2 mm, the drawing liquid temperature is 30°C, and the drawing speed is 120 m / min; S5.2, then the thin drawing is performed at a die elongation of 9%, the diameter is changed from 0.2 mm to 0.07 mm, the drawing liquid temperature is 30°C, and the drawing speed is 300 m / min; S5.3, finally, the ultra-thin drawing is performed at a die elongation of 6%, the diameter is changed from 0.07 mm to the target diameter: 18 μm, 20 μm, 23 μm, 25 μm, 30 μm, 35 μm and 40 μm, the drawing liquid temperature is 30°C, and the drawing speed is 450 m / min.

[0039] Comparative Example 4 A high-reliability ball-welding gold wire, comprising the following raw materials and the same weight parts as Example 1; The specific preparation method of the high-reliability ball-welding gold wire is different from that of Example 1, and the difference is that the hot extrusion of S2 to prepare the thick gold rod is directly drawn to prepare the gold wire The preparation of the uniformly composed gold ingot of step S1 and the hot extrusion of S2 to prepare the thick gold rod are the same as those of Example 1, and the hot extrusion of S2 to prepare the thick gold rod is drawn to prepare the gold wire, that is: S3, the large-medium-thin-ultra-thin drawing of the gold wire: S5.1, the thick gold rod of step S2 is first subjected to medium drawing treatment: the diameter is changed from 10 mm to 2 mm, the reduction rate is 13%, the drawing liquid temperature is 30°C, and the drawing speed is 20 m / min; S5.2, then subjected to medium drawing treatment: the diameter is changed from 2 mm to 0.2 mm, the reduction rate is 13%, the drawing liquid temperature is 30°C, and the drawing speed is 60 m / min; S5.3, then subjected to thin drawing treatment: the diameter is changed from 0.2 mm to 0.07 mm, the reduction rate is 13%, the drawing liquid temperature is 30-35°C, and the drawing speed is 200 m / min; S5.4, finally, subjected to micro drawing treatment: the diameter is changed from 0.07 mm to 0.025 mm, the reduction rate is 13%, the drawing liquid temperature is 30-35°C, and the drawing speed is 400 m / min; Then, the gold wire annealing treatment of S6 and the rewinding and packaging of S7 of Example 1 are sequentially performed.

[0040] Performance test 1. The gold wires of target diameters prepared in Examples 1-4 and Comparative Examples 1-4 were tested for mechanical properties of BL (g) and EL (%). The reference standards for the mechanical properties of BL (g) and EL (%) are shown in Table 1, and the test results are shown in Table 2.

[0041] Table 1 Standard reference

[0042] Table 2 Performance test of gold wire

[0043] It can be seen from Table 1 and Table 2 that Examples 1 to 4 of the present invention select different doping elements, optimize the content of alloying elements, and use hot extrusion, rolling, intermediate annealing, medium-fine-micro-drawing and other processes to prepare gold wires with good grain size, uniform bump grains, and stable heat-affected zone length, thereby improving the consistency of the coplanarity of the gold bumps during ball welding; and Examples 1 to 4 effectively improve the internal grain size of the gold wire by combining the melting-hot extrusion-rolling process, thereby greatly improving the wire strength and elongation; in addition, the doping element ratio used in Example 4 enables the gold wire to have better strength and elongation through the melting-hot extrusion-rolling process.

[0044] 2. The 25 μm gold wires prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were bonded, and the IMC growth trend was tested after bonding. At the same time, pure gold wire was used as a control group. Figure 3 shown.

[0045] from Figure 3 The results show that the IMC thickness of the high-reliability gold ball solder wires prepared in Examples 1-4 of the present invention slowly increased. After 696 hours, the optimal IMC thickness was still maintained, ranging from 3 to 5.5 μm. IMC thickness is crucial to soldering reliability, and its ideal range is typically 3 to 5 μm. This is mainly due to the fact that the doping element reduces the diffusion of chip aluminum and optimizes the IMC thickness. Too thin or too thick will lead to reduced solder joint reliability, thus achieving high bonding reliability. This also demonstrates that the gold wire has the best balance of comprehensive mechanical properties, conductivity, and thermal fatigue life. The gold wire of Example 4 has superior performance; the reliability of the high-reliability gold ball solder wires prepared in Examples 1-4 of the present invention is superior to that of existing market products.

[0046] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit and essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and all changes falling within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

[0047] Furthermore, it should be understood that although the present specification describes particular embodiments, each of which contains only a single independent technical solution, the specification is written so as to cover all combinations of those previously claimed independent technical solutions. It is therefore anticipated that each of the independent technical solutions can also be implemented by means of any other of the independent technical solutions, even if that particular implementation is not explicitly described or can constitute a combination of features of different embodiments.

Claims

1. A high reliability ball bonding gold wire, characterized in that: The invention comprises the following raw materials and their weight parts: Be 2-10ppm, Ca 0-30ppm, Pd 5-20ppm, Pt 5-20ppm, Al 5-20ppm, Mg 0-20ppm, Ce 5-30ppm, La 0-20ppm, Y 0-30ppm, Gd 0-30ppm and Bi 2-30ppm, and the total added content is ≤100ppm, and the remaining content is Au with a purity of 99.999wt%; The high-reliability ball bonding gold wire is prepared by sequentially subjecting raw material components to vacuum melting, hot extrusion, rolling, intermediate annealing, medium-fine-micro drawing and annealing.

2. The high reliability ball bonding gold wire according to claim 1, characterized in that: The invention comprises the following raw materials and their weight proportions: Be 6ppm, Pd 10ppm, Pt 15ppm, Al 10ppm, Cerium Ce 18ppm, Gd 5ppm and Bi 8ppm, and the balance is Au with a purity of 99.999wt%.

3. A method for preparing a high-reliability ball bonding gold wire according to claim 1 or 2, characterized in that: The following steps are involved: S1. Preparation of gold ingot with uniform composition: According to the target weight of the raw materials, the doping element and the gold element are vacuum melted to form a gold ingot with uniform composition; S2. Hot extrusion to prepare a coarse gold rod: The gold ingot with uniform composition in step S1 is hot extruded to prepare a coarse gold rod with dense structure and fine grains; S3, rolling to prepare thin gold rods: the thick gold rods in step S2 are further refined by rolling to form thin gold rods; S4, intermediate annealing of thin gold rods: The thin gold rods from step S3 are subjected to intermediate annealing to form thin gold rods with better structural consistency: S5, medium-fine-micro-drawing to prepare gold wire: The thin gold rod in step S4 is sequentially drawn through medium drawing, fine drawing, and micro-drawing to form gold wire: S6, gold wire annealing treatment: anneal the gold wire in step S5 to obtain a finished gold wire.

4. The method for preparing a high-reliability ball bonding gold wire according to claim 3, wherein: The specific preparation process is as follows: S1. Preparation of gold ingots with uniform composition S1.

1. Prepare materials: gold particles with a purity of 99.999wt%, palladium particles with a purity of 99.95wt%, platinum particles with a purity of 99.95wt%, beryllium particles with a purity of 99.95wt%, calcium particles with a purity of 99.95wt%, aluminum particles with a purity of 99.99wt%, magnesium particles with a purity of 99.95wt%, cerium particles with a purity of 99.5wt%, yttrium particles with a purity of 99.9wt%, lanthanum particles with a purity of 99.9wt%, and gadolinium particles with a purity of 99.9wt%. S1.2, Gold ingot refining: Use medium frequency induction melting furnace, refine under vacuum conditions to remove non-gaseous elements, and cast into hollow gold sleeves; S1.

3. Melting of master alloys: According to the target weight, high-purity gold raw materials (purity 99.999wt%) with a weight ratio of 99.20-99.60wt% and additive elements with a weight ratio of 0.40-0.80wt% are weighed to prepare Au-Pt-Pd, Au-Be, Au-Ca, Au-Al, Au-Mg, Au-Ce, Au-Y, Au-La and Au-Gd master alloys. When melting each master alloy, the additive elements are placed in a hollow gold sleeve, placed in a crucible for vacuum refining, and after melting, stirred for 30-50 times, allowed to stand for 5-30 minutes, and cast into ingots. The ingot casting is repeated 2-3 times to form different master alloy ingots for standby use; S1.4, Vacuum Melting: Weigh each master alloy ingot according to the doping element content, with the total doping element content ≤ 100 ppm and the balance gold ≥ 99.99 wt% for feeding. Place the master alloy in a hollow gold sleeve and then place it in a crucible for vacuum refining. After the material is melted, stir it 20-50 times, let it stand for 5-30 minutes, and then cast it into an ingot. Repeat the ingot casting 2-3 times to obtain a gold ingot with uniform composition. S2. Preparation of rough gold rods by hot extrusion: Hot extrusion: The gold ingot with uniform composition obtained in step S1.4 is heated and hot extruded using a hot extruder, and the gold ingot is directly reduced in diameter to 9-11 mm to obtain a thick gold rod; S3. Rolling to prepare thin gold bars: Rolling: rolling the thick gold rod from step S2 to 1.54-1.56 mm to obtain a thin gold rod; S4, intermediate annealing treatment of thin gold rods: Intermediate annealing: annealing the thin gold rod in step S3 at 200-500°C for 2-4 hours, followed by furnace cooling to obtain the intermediate annealed thin gold rod; S5, medium-fine-micro-drawing gold wire preparation: S5.

1. The thin gold rod prepared in step S4 is first subjected to intermediate drawing: the diameter is reduced from 1.54-1.56 mm to 0.2 mm, the surface reduction rate is 13%, the drawing liquid temperature is 30-35°C, and the drawing speed is 60-100 m / min; S5.2, then fine drawing treatment: diameter reduction from 0.2mm to 0.07mm, surface reduction rate 13%, drawing liquid temperature 30~35℃, drawing speed 200~250m / min; S5.

3. Finally, micro-drawing treatment: reduce the diameter from 0.07mm to the target diameter, reduce the surface area by 13%, use the drawing liquid temperature of 30-35℃, and draw the wire at a speed of 300-400m / min; S6, gold wire annealing treatment: Finished product annealing: the gold wire in step S5 is annealed at a temperature of 400-600° C. and an annealing speed of 30-50 m / min.

5. The method for preparing a high-reliability ball bonding gold wire according to claim 4, wherein: In step S2, the heating conditions for hot extrusion are: mold preheating 400~600℃, gold ingot heating temperature 500~700℃, holding time 1~2h; hot extrusion conditions: Hot extrusion speed 10~20mm / s.

6. The method for preparing a high-reliability ball bonding gold wire according to claim 4, wherein: In step S3, the rolling is continuous cold rolling.

7. The method for preparing a high-reliability ball bonding gold wire according to claim 4, characterized in that: In step S3, the deformation amount of each rolling pass is 5-20%.

8. The method for preparing a high-reliability ball bonding gold wire according to claim 6, wherein: In step S5.3, the target diameter of the gold wire is 15-50 μm.

9. The method for preparing a high-reliability ball bonding gold wire according to claim 6, wherein: In steps S1.3 and S1.4, the gold ingot refining conditions are: vacuum degree 1×10 -3 Pa, refining power 16~24kw, melting temperature 1200~1400℃, refining time 1~2h.

10. The method for preparing a high-reliability ball bonding gold wire according to claim 6, wherein: In step S1.2, the size of the hollow gold sleeve is 10-50 mm in inner diameter, 15-55 mm in outer diameter, 2-5 mm in thickness and 50-100 mm in height; in step S1.4, the size of the gold ingot is 50-90 mm in diameter and 20-100 mm in height.

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