Palladium / gold plated copper bonding wire, and electroplating process therefor

Abstract

To provide a palladium / gold plated copper bonding wire of high plated layer coverage, not easily peeling off and reinforcing the protection for baseline copper, with the wire body and the end thereof being not easily oxidized after welding and not easily corroded by an acid or an alkali, and an electroplating process therefor.SOLUTION: The electroplating method for palladium / gold plated copper bonding wire, including the steps of electroplating a first layer of palladium on the surface of baseline copper using a first palladium plating solution, plating a second layer of gold thereon using a first gold plating solution to obtain a semi-processed plated product, subsequently plating a third layer of palladium on the semi-processed plated product using a second palladium plating solution, and finally plating a fourth layer of gold thereon using a second gold plating solution to obtain a finished plated product, is characterized in that the first palladium plating solution includes palladium tetraaminoacetate, 4-carboxybenzenesulfonamide, and 6-azauracil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This application relates to the field of electroplating technology, and more particularly to palladium gold plated copper bonding wire and electroplating process thereof. [Background technology]

[0002] Bonding wire generally uses inexpensive metal as a core wire, and the outer surface of the core wire is plated with a precious metal layer that is acid-resistant, alkali-resistant, and oxidation-resistant. It can be used to connect semiconductor packages such as LEDs and ICs, such as pins and silicon wafers, to transmit electrical signals. Bonding wire is inexpensive and can replace traditional gold wires, etc., to reduce costs. A typical bonding wire should have excellent electrical, thermal conductivity, mechanical properties, and chemical stability. However, some related bonding wires have problems such as insufficient plating layer coverage and vulnerability to chemical corrosion after welding. Summary of the Invention [Problem to be solved by the invention]

[0003] In order to improve the problems of some related bonding wires such as insufficient plating layer coverage and vulnerability to chemical corrosion after welding, the present application provides a palladium-gold plated copper bonding wire and its electroplating process, and adopts the following technical solutions: [Means for solving the problem]

[0004] In a first aspect, the present application provides an electroplating process for palladium-gold plated copper bonding wire, and adopts the following technical solutions:

[0005] 1. A process for electroplating palladium gold plated copper bonding wire, the process comprising: The method includes electroplating a first palladium layer on a baseline copper surface using a first palladium plating solution, plating a second gold layer using a first gold plating solution to obtain a plated blank, plating a third palladium layer on the plated blank using a second palladium plating solution, and finally plating a fourth gold layer using a second gold plating solution to obtain a finished plated product, wherein the first palladium plating solution comprises palladium tetraaminoacetate, 4-carboxybenzenesulfonamide and 6-azauracil.

[0006] By adopting the above technical solution, in the first palladium plating solution, both ends of palladium in tetraaminopalladium acetate are bonded to two acetate groups, which can be complexed with the sulfonamide group and carboxyl group at both ends of 4-carboxybenzenesulfonamide; 6-azauracil has a heterocycle of pyrimidopyrimidine and a carbonyl group in the heterocycle, which can form mutually attractive electron groups with the sulfonamide group and carboxyl group of 4-carboxybenzenesulfonamide to form a complex; thus, the deposition rate of palladium is buffered, the deposition rate of palladium is uniform at each point on the surface of the copper base material, the palladium deposition crystal grains are fine, and the complex structure of 4-carboxybenzenesulfonamide and 6-azauracil can also prevent other impurities from approaching the surface of the baseline copper; the thickness of the obtained first palladium layer is uniform, and a dense first palladium layer is obtained, and the plating layer coverage is high, and bubbles, protrusions, plating leakage, etc. are not easily generated; the purity of the first palladium layer is high, and the baseline copper is not easily peeled off. After electroplating a dense first palladium layer on the surface of the baseline copper, it contributes to improving the adhesion of the bonding of the second gold layer, the third palladium layer and the fourth gold layer that are electroplated later, and has the effects of each electroplating layer not peeling off easily, each plating layer has a high coverage, reinforcing the protection of the baseline copper, making the baseline copper not oxidized and not corroded by acid and alkali, and efficiently conducting electric charges. Copper, palladium and gold all have a certain plasticity, so that both ends are melted during welding to form a spherical or oval piece, and each plating layer can still be coated on the baseline copper, not easily cracked, not easily peeled off, effectively protecting the copper core so that the copper core is not oxidized or corroded by acid and alkali, and improving the reliability and service life of the bonding wire.

[0007] As an improvement to the electroplating process of the palladium gold plated copper bonding wire, during the electroplating process, the concentration of the palladium tetraaminoacetate is maintained at 5 to 8 g / L, the concentration of the 4-carboxybenzenesulfonamide is maintained at 5 to 15 mg / L, and the concentration of the 6-azauracil is maintained at 1 to 5 mg / L in the first palladium plating solution.

[0008] By adopting the above technical solution, a dense first palladium layer can be produced and obtained. If the concentration of tetraaminopalladium acetate is too high, it will affect the uniformity of deposition, and if it is too low, the efficiency of the plating film will be too low and the plating film will be prone to unevenness. If the concentrations of 4-carboxybenzenesulfonamide and 6-azauracil are too high, the complexing effect will be enhanced, reducing the deposition efficiency, which will also result in unevenness of the plating film, and if they are too low, the complexing effect will be weakened, which will also affect the uniformity of deposition.

[0009] As an improvement to the electroplating process of the palladium gold plated copper bonding wire, the first palladium plating solution further comprises methionine, and the concentration of the methionine in the first palladium plating solution is 10-20 mg / L.

[0010] By adopting the above technical solution, methionine contains a chain-like terminal carboxyl group, a terminal amino group and a carbon-sulfur bond, and can combine with 4-carboxybenzenesulfonamide and 6-azauracil, which enhances the desorption efficiency after palladium deposition, quickly reactivates 4-carboxybenzenesulfonamide and 6-azauracil, and improves the operating efficiency.

[0011] In an improvement to the palladium gold plated copper bonding wire electroplating process, the second palladium plating solution includes a palladium salt, 3-chloro-4-fluoroaniline, calcium dinonanephthalene sulfonate, and β-cyanoalanine.

[0012] By adopting the above technical solution, 3-chloro-4-fluoroaniline has a strong attraction effect on palladium atoms and can complex palladium salts, dinonane naphthalene calcium sulfonate has the effect of dispersing 3-chloro-4-fluoroaniline, and β-cyanoalanine has the effect of stabilizing the dispersion effect, improving the uniformity and density of palladium deposition and obtaining a third palladium layer with a high coverage rate. The third palladium layer can be firmly coated on the second gold layer and can provide an extremely strong bonding force for the attachment of the fourth gold layer.

[0013] In an improvement to the palladium gold plated copper bonding wire electroplating process, the palladium salt is one or more of tetraaminopalladium dichloride, dinitrodiamminepalladium, diaminopalladium dichloride, and trans-diaminopalladium dibromide.

[0014] By adopting the above technical solutions, the palladium salts are all complexed with 3-chloro-4-fluoroaniline, dispersed with calcium dinonanesulfonate, and stabilized with β-cyanoalanine, which can reduce the deposition rate on the baseline copper and make the deposition film at each point uniform and dense.

[0015] As an improvement to the electroplating process for the palladium gold plated copper bonding wire, during the electroplating process, the concentration of the palladium salt is maintained at 6 to 10 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 3 to 13 mg / L, the concentration of the calcium dinonanephthalenesulfonate is maintained at 2 to 6 mg / L, and the concentration of the β-cyanoalanine is maintained at 12 to 22 mg / L in the second palladium plating solution.

[0016] By adopting the above technical solution, a second palladium layer that is dense and can be firmly connected to the gold layers on both sides can be manufactured and obtained. If the concentration of palladium salt is too high, it will affect the uniformity of deposition, and if it is too low, the efficiency of the plating film will be too low and the plating film will be prone to unevenness. If the concentration of 3-chloro-4-fluoroaniline is too high, the complexing effect will be enhanced, decreasing the deposition efficiency, similarly causing unevenness in the plating film, and if it is too low, the complexing effect will be weakened, similarly affecting the uniformity of deposition. If the concentration of calcium dinonane naphthalene sulfonate is too high or too low, the dispersing effect will be weakened. If the concentration of β-cyanoalanine is too high or too low, the stabilizing effect will be reduced.

[0017] In the electroplating process of the palladium gold-plated copper bonding wire, the first gold plating solution and the second gold plating solution are both potassium aurous cyanide solutions, and the pH of the first gold plating solution and the second gold plating solution is both 10 to 15 during the electroplating process adjusted with ammonia water.

[0018] By adopting the above technical solution, in alkaline liquid, hydroxide serves as an electron-withdrawing group to balance the electron-attracting deposition of gold ions, improving the efficiency of gold electroplating.

[0019] An improvement to the electroplating process of the palladium gold plated copper bonding wire, wherein the baseline copper diameter is 180-220 μm, the electroplating process further comprises a step of performing a first wiredrawing on the plated blank to a post-drawing diameter of 90-105 μm, and the electroplating process further comprises a step of performing a second wiredrawing on the plated finished product to a post-drawing diameter of 15-22 μm.

[0020] By adopting the above technical solution, the thick wire is drawn twice, and the electroplating efficiency is higher than that of the thin wire, and both the copper and the electroplating layer have good ductility, and the coating of the plating layer is still saturated after drawing.

[0021] As an improvement to the electroplating process of the palladium gold plated copper bonding wire, in the process of electroplating the first palladium layer, the second gold layer, the third palladium layer and the fourth gold layer, the electroplating temperature is set to 70 to 85°C, the current is set to 10 to 80 mA, and the electroplating time for each layer is set to 10 to 30 minutes.

[0022] By adopting the above technical solution, the electroplating parameters of temperature, current and time are adopted, and the electroplating efficiency is high, the plating layer is flat and dense, and the adhesion is strong.

[0023] In a second aspect, the present application further provides a palladium-gold plated copper bonding wire, and adopts the following technical solutions:

[0024] A palladium-gold plated copper bonding wire is produced by the electroplating process, the palladium-gold plated copper bonding wire comprising, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer.

[0025] By adopting the above technical solution, a copper bonding wire plated with a first palladium layer, a second gold layer, a third palladium layer and a fourth gold layer can be manufactured, and the plating film of each layer is uniform, has a high coverage rate, has strong adhesion, is not easy to tear or peel off, and even after the end is deformed after welding, the copper core is still completely covered by each plating layer, so it is resistant to chemical corrosion, and is applicable to electronic products such as LEDs, with high electrical and thermal conductivity and high reliability. Effect of the Invention

[0026] In summary, the present palladium gold plated copper bonding wire and its electroplating process have the following beneficial effects:

[0027] In this palladium gold-plated copper bonding wire, the complexing and buffering actions of the components in the first palladium plating solution make the palladium deposition rate uniform at each location on the surface of the copper base material, refine the palladium deposition crystal grains, and obtain a dense first palladium layer. The plating layer has a high coverage rate and the baseline copper is less likely to peel off.

[0028] After electroplating a dense first palladium layer on the surface of the baseline copper, it contributes to improving the adhesion of the second gold layer, the third palladium layer and the fourth gold layer which are electroplated later. Each electroplated layer is not easily peeled off, and the coverage rate of each plating layer is high, reinforcing the protection of the baseline copper. After welding, the wire body and ends are not easily oxidized, and are not easily corroded by acids or alkalis. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is an SEM image of a spherical tip made of palladium-gold plated copper bonding wire produced in Example 1 after electrolytic etching. [Diagram 2] FIG. 13 is an SEM image of a spherical tip made from a palladium-gold plated copper bonding wire produced in Control Example 6 after galvanic etching. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Example 1 In this embodiment, a palladium-gold plated copper bonding wire is manufactured by an electroplating process, the electroplating process comprising: The method includes electroplating a first palladium layer on a baseline copper surface using a first palladium plating solution, further plating a second gold layer using a first gold plating solution to obtain a plated blank, then plating a third palladium layer on the plated blank using a second palladium plating solution, and finally plating a fourth gold layer using a second gold plating solution to obtain a plated finished product, i.e., a palladium gold plated copper bonding wire, which is, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer.

[0031] In the process of electroplating the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, the electroplating temperature is set to 70° C., the current is set to 10 mA, and the plating time of each layer is set to 10 min.

[0032] The first palladium plating solution contains palladium tetraaminoacetate, 4-carboxybenzenesulfonamide and 6-azauracil. During the electroplating process, the first palladium plating solution is maintained at a concentration of 7 to 8 g / L, a concentration of 4-carboxybenzenesulfonamide at 12 to 15 mg / L, and a concentration of 6-azauracil at 1 to 2 mg / L.

[0033] The second palladium plating solution contains tetraaminopalladium dichloride, 3-chloro-4-fluoroaniline, calcium dinonanaphthalenesulfonate, and β-cyanoalanine. During the electroplating process, the second palladium plating solution is maintained at a concentration of 6 to 8 g / L for the tetraaminopalladium dichloride, 10 to 13 mg / L for the 3-chloro-4-fluoroaniline, 2 to 4 mg / L for the calcium dinonanaphthalenesulfonate, and 18 to 22 mg / L for the β-cyanoalanine.

[0034] The first gold plating solution and the second gold plating solution are both potassium aurous cyanide solutions. In the electroplating process, the concentration of potassium aurous cyanide in the first gold plating solution and the second gold plating solution is maintained at 6 to 8 g / L and adjusted with ammonia water, and the pH of the first gold plating solution and the second gold plating solution is both 10 to 12.5.

[0035] Example 2 In this embodiment, compared with Example 1, the temperature, current, and time of electroplating, as well as the mixing ratio of each plating solution, pH, and type of palladium salt were adjusted, specifically as follows.

[0036] In this embodiment, a palladium-gold plated copper bonding wire is manufactured by an electroplating process, the electroplating process comprising: The method includes electroplating a first palladium layer on a baseline copper surface using a first palladium plating solution, further plating a second gold layer using a first gold plating solution to obtain a plated blank, then plating a third palladium layer on the plated blank using a second palladium plating solution, and finally plating a fourth gold layer using a second gold plating solution to obtain a plated finished product, i.e., a palladium gold plated copper bonding wire, which is, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer.

[0037] In the process of electroplating the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, the electroplating temperature is set to 85° C., the current is set to 80 mA, and the plating time of each layer is set to 30 min.

[0038] The first palladium plating solution contains palladium tetraaminoacetate, 4-carboxybenzenesulfonamide and 6-azauracil. During the electroplating process, the first palladium plating solution is maintained at a concentration of 5 to 6 g / L, a concentration of 5 to 8 mg / L, and a concentration of 4 to 5 mg / L.

[0039] The second palladium plating solution contains dinitrodiamminepalladium, 3-chloro-4-fluoroaniline, calcium dinonanaphthalenesulfonate, and β-cyanoalanine. During the electroplating process, the concentration of the dinitrodiamminepalladium is maintained at 8 to 10 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 3 to 5 mg / L, the concentration of the calcium dinonanaphthalenesulfonate is maintained at 4 to 6 mg / L, and the concentration of the β-cyanoalanine is maintained at 12 to 15 mg / L in the second palladium plating solution.

[0040] The first gold plating solution and the second gold plating solution are both potassium aurous cyanide solutions. In the electroplating process, the concentration of potassium aurous cyanide in the first gold plating solution and the second gold plating solution is maintained at 6 to 8 g / L and adjusted with ammonia water, and the pH of the first gold plating solution and the second gold plating solution is both 13 to 15.

[0041] Example 3 In this embodiment, compared with Example 1, the temperature, current, and time of electroplating, as well as the compounding ratio of each plating solution, pH, and type of palladium salt were adjusted, and methionine was further added to the first palladium plating solution, as follows.

[0042] In this embodiment, a palladium-gold plated copper bonding wire is manufactured by an electroplating process, the electroplating process comprising: The method includes electroplating a first palladium layer on a baseline copper surface using a first palladium plating solution, further plating a second gold layer using a first gold plating solution to obtain a plated blank, then plating a third palladium layer on the plated blank using a second palladium plating solution, and finally plating a fourth gold layer using a second gold plating solution to obtain a plated finished product, i.e., a palladium gold plated copper bonding wire, which is, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer.

[0043] In the process of electroplating the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, the electroplating temperature is set to 75° C., the current is set to 40 mA, and the plating time of each layer is set to 20 min.

[0044] The first palladium plating solution contains palladium tetraaminoacetate, 4-carboxybenzenesulfonamide, 6-azauracil, and methionine. During electroplating, the first palladium plating solution is maintained at a concentration of 6 to 7 g / L, a concentration of 4-carboxybenzenesulfonamide at 9 to 11 mg / L, a concentration of 6-azauracil at 3 to 4 mg / L, and a concentration of methionine at 10 to 12 mg / L.

[0045] The second palladium plating solution contains diaminopalladium dichloride, 3-chloro-4-fluoroaniline, calcium dinonanaphthalenesulfonate, and β-cyanoalanine. During the electroplating process, the concentration of the diaminopalladium dichloride is maintained at 7 to 8.5 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 8 to 10 mg / L, the concentration of the calcium dinonanaphthalenesulfonate is maintained at 3 to 4 mg / L, and the concentration of the β-cyanoalanine is maintained at 16 to 18 mg / L in the second palladium plating solution.

[0046] The first gold plating solution and the second gold plating solution are both potassium aurous cyanide solutions. In the electroplating process, the concentration of potassium aurous cyanide in the first gold plating solution and the second gold plating solution is maintained at 6 to 7 g / L and adjusted with ammonia water, and the pH of the first gold plating solution and the second gold plating solution is both 12 to 13.

[0047] Example 4 In this embodiment, compared with Example 1, the temperature, current, and time of electroplating, as well as the compounding ratio of each plating solution, pH, and type of palladium salt were adjusted, and methionine was further added to the first palladium plating solution, as follows.

[0048] In this embodiment, a palladium-gold plated copper bonding wire is manufactured by an electroplating process, the electroplating process comprising: The method includes electroplating a first palladium layer on a baseline copper surface using a first palladium plating solution, further plating a second gold layer using a first gold plating solution to obtain a plated blank, then plating a third palladium layer on the plated blank using a second palladium plating solution, and finally plating a fourth gold layer using a second gold plating solution to obtain a plated finished product, i.e., a palladium gold plated copper bonding wire, which is, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer.

[0049] In the process of electroplating the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, the electroplating temperature is set to 73° C., the current is set to 60 mA, and the plating time of each layer is set to 25 min.

[0050] The first palladium plating solution contains palladium tetraaminoacetate, 4-carboxybenzenesulfonamide, 6-azauracil, and methionine. During electroplating, the first palladium plating solution is maintained at a concentration of 6 to 7 g / L, a concentration of 4-carboxybenzenesulfonamide at 8 to 10 mg / L, a concentration of 6-azauracil at 4 to 5 mg / L, and a concentration of methionine at 18 to 20 mg / L.

[0051] The second palladium plating solution contains trans-diaminopalladium dibromide, 3-chloro-4-fluoroaniline, calcium dinonanaphthalenesulfonate, and β-cyanoalanine. During the electroplating process, the second palladium plating solution is maintained at a concentration of 8 to 9 g / L for the trans-diaminopalladium dibromide, 6 to 8 mg / L for the 3-chloro-4-fluoroaniline, 5 to 6 mg / L for the calcium dinonanaphthalenesulfonate, and 20 to 22 mg / L for the β-cyanoalanine.

[0052] The first gold plating solution and the second gold plating solution are both potassium aurous cyanide solutions. In the electroplating process, the concentration of potassium aurous cyanide in the first gold plating solution and the second gold plating solution is maintained at 7 to 8 g / L and adjusted with ammonia water, and the pH of the first gold plating solution and the second gold plating solution is both 11 to 12.

[0053] Example 5 In this embodiment, compared with Example 1, the temperature, current, and time of electroplating, as well as the compounding ratio of each plating solution, pH, and type of palladium salt were adjusted, and methionine was further added to the first palladium plating solution, as follows.

[0054] In this embodiment, a palladium-gold plated copper bonding wire is manufactured by an electroplating process, the electroplating process comprising: The present invention includes the steps of: selecting a baseline copper having a diameter of 200 μm, electroplating a first palladium layer on the surface of the baseline copper using a first palladium plating solution, further plating a second gold layer using a first gold plating solution to obtain a plated blank, performing a first wiredrawing on the plated blank so that the diameter after wiredrawing is 97 μm, then plating a third palladium layer on the plated blank using a second palladium plating solution, and finally plating a fourth gold layer using a second gold plating solution to obtain a plated finished product, performing a second wiredrawing on the plated finished product so that the diameter after wiredrawing is 18 μm, and the resulting palladium-gold plated copper bonding wire is, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, in that order.

[0055] In the process of electroplating the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, the electroplating temperature is set to 77° C., the current is set to 35 mA, and the plating time of each layer is set to 30 min.

[0056] The first palladium plating solution contains palladium tetraaminoacetate, 4-carboxybenzenesulfonamide, 6-azauracil, and methionine, and during electroplating, the first palladium plating solution is maintained at a concentration of 6 to 7 g / L, a concentration of 4-carboxybenzenesulfonamide at 11 to 13 mg / L, a concentration of 6-azauracil at 4 to 5 mg / L, and a concentration of methionine at 14 to 16 mg / L.

[0057] The second palladium plating solution contains diaminopalladium dichloride, 3-chloro-4-fluoroaniline, calcium dinonanaphthalenesulfonate, and β-cyanoalanine. During the electroplating process, the concentration of the diaminopalladium dichloride is maintained at 6 to 7 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 10 to 12 mg / L, the concentration of the calcium dinonanaphthalenesulfonate is maintained at 3 to 4.5 mg / L, and the concentration of the β-cyanoalanine is maintained at 15 to 17 mg / L in the second palladium plating solution.

[0058] The first gold plating solution and the second gold plating solution are both potassium aurous cyanide solutions. In the electroplating process, the concentration of potassium aurous cyanide in the first gold plating solution and the second gold plating solution is maintained at 7 to 8 g / L and adjusted with ammonia water, and the pH of the first gold plating solution and the second gold plating solution is both 12 to 13.

[0059] Control Example 1 This control example adopts the same technical solution as in Example 1, except that 4-carboxybenzenesulfonamide is removed from the first palladium plating solution. That is, the first palladium plating solution contains palladium tetraaminoacetate and 6-azauracil. During the electroplating process, the concentration of the palladium tetraaminoacetate is maintained at 7 to 8 g / L and the concentration of the 6-azauracil is maintained at 1 to 2 mg / L in the first palladium plating solution.

[0060] Finally, palladium-gold plated copper bonding wires are produced and obtained.

[0061] Control Example 2 This control example adopts the same technical solution as in Example 1, except that 6-azauracil is removed from the first palladium plating solution. That is, the first palladium plating solution contains palladium tetraaminoacetate and 4-carboxybenzenesulfonamide. During the electroplating process, the concentration of the palladium tetraaminoacetate is maintained at 7 to 8 g / L and the concentration of the 4-carboxybenzenesulfonamide is maintained at 12 to 15 mg / L in the first palladium plating solution.

[0062] Finally, palladium-gold plated copper bonding wires are produced and obtained.

[0063] Control Example 3 This control example adopts the same technical solution as in Example 1, except that 3-chloro-4-fluoroaniline is removed from the second palladium plating solution. That is, the second palladium plating solution contains tetraaminopalladium dichloride, calcium dinonanaphthalenesulfonate, and β-cyanoalanine. During the electroplating process, the concentration of the tetraaminopalladium dichloride is maintained at 6 to 8 g / L, the concentration of the calcium dinonanaphthalenesulfonate is maintained at 2 to 4 mg / L, and the concentration of the β-cyanoalanine is maintained at 18 to 22 mg / L in the second palladium plating solution.

[0064] Finally, palladium-gold plated copper bonding wires are produced and obtained.

[0065] Control Example 4 This control example adopts the same technical solution as in Example 1, except that calcium dinonane naphthalene sulfonate is removed from the second palladium plating solution. That is, the second palladium plating solution contains tetraaminopalladium dichloride, 3-chloro-4-fluoroaniline, and β-cyanoalanine. During the electroplating process, the concentration of the tetraaminopalladium dichloride is maintained at 6 to 8 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 10 to 13 mg / L, and the concentration of the β-cyanoalanine is maintained at 18 to 22 mg / L in the second palladium plating solution.

[0066] Finally, palladium-gold plated copper bonding wires are produced and obtained.

[0067] Control Example 5 This control example adopts the same technical solution as in Example 1, except that β-cyanoalanine is removed from the second palladium plating solution. That is, the second palladium plating solution contains tetraaminopalladium dichloride, 3-chloro-4-fluoroaniline, and calcium dinonanaphthalenesulfonate. During the electroplating process, the concentration of the tetraaminopalladium dichloride is maintained at 6 to 8 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 10 to 13 mg / L, and the concentration of the calcium dinonanaphthalenesulfonate is maintained at 2 to 4 mg / L in the second palladium plating solution.

[0068] Finally, palladium-gold plated copper bonding wires are produced and obtained.

[0069] Control Example 6 This control example differs from Example 1 only in that the components of the first palladium plating solution and the second palladium plating solution are different, and adopts a similar technical solution to Example 1, specifically as follows:

[0070] The first palladium plating solution used in this comparative example contains tetraaminopalladium dichloride, ethylenediamine (as a ligand), and sodium sulfate (to enhance the conductivity of the solution). During the electroplating process, the concentration of tetraaminopalladium dichloride, the concentration of ethylenediamine, and the concentration of sodium sulfate in the first palladium plating solution are maintained at 7-8 g / L, 1-2 g / L, and 5-6 g / L, respectively.

[0071] The component mixing ratios of the second palladium plating solution and the first palladium plating solution employed in this comparative example are both the same.

[0072] Finally, palladium-gold plated copper bonding wires are produced and obtained.

[0073] Test Example 1 The palladium-gold plated copper bonding wires produced in Examples 1 to 5 and Comparative Examples 1 to 6 were subjected to resistivity and repeated bending-tensile tests. The results are shown in Table 1.

[0074] JPEG2025003923000002.jpg245165JPEG2025003923000003.jpg37126

[0075] As can be seen from the results in Table 1, the palladium gold-plated copper bonding wires produced in Examples 1 to 5 had a flat and shiny appearance, low electrical resistivity, and good bending resistance, which were superior to the results of Control Examples 1 to 6. This was caused by the effects of each component of the first palladium plating solution and each component of the second palladium plating solution on the uniformity of the plating film, the fineness of the precipitated crystal grains, etc.

[0076] Test Example 2 After the bonding wire is welded, the location that is likely to corrode and become ineffective is generally the weld tip, and the tip is generally spherical or oval. Therefore, the tip of the palladium gold-plated copper bonding wire produced in Example 1 and Comparative Example 6 was made spherical, and an electrolytic corrosion test (corresponding to an accelerated corrosion test) was performed on the spherical tip in accordance with the GB / T6466-2008 standard. SEM images of the bonding wire end after electrolytic corrosion are shown in Figures 1 and 2. Figure 1 is an SEM image of the spherical tip of the palladium gold-plated copper bonding wire produced in Example 1 after electrolytic corrosion. Figure 2 is an SEM image of the spherical tip of the palladium gold-plated copper bonding wire produced in Comparative Example 6 after electrolytic corrosion.

[0077] As can be seen from comparing Figures 1 and 2, the spherical tip in Figure 1 has relatively few cracks after accelerated corrosion, while the spherical tip in Figure 2 has relatively more cracks after accelerated corrosion, and the palladium gold plated copper bonding wire manufactured by the solution of Example 1 has better corrosion resistance.

[0078] Test Example 3 Instead of the baseline copper of Examples 1-5 and Control Examples 1-6, eleven of the same copper pieces were used to manufacture palladium gold-plated copper pieces using the solutions of Examples 1-5 and Control Examples 1-6, respectively. Surface coverage tests were conducted on the eleven palladium gold-plated copper pieces, and the results are shown in Table 2.

[0079] JPEG2025003923000004.jpg9955

[0080] As can be seen from the results in Table 2, the manufacturing processes of Examples 1 to 5 can achieve a coverage rate of 99.2 to 99.7% relative to the base layer, which is significantly higher than the results of Control Examples 1 to 6. Here, the coverage rate of the plating layer is the highest in Examples 3 and 4, which is due to the addition of methionine to the first palladium plating solution compared to Example 1, thereby further improving the coverage rate of the plating film.

[0081] As can be seen from the above, the palladium gold-plated copper bonding wire manufactured by the solution of this embodiment has the advantages of high plating film uniformity and coverage, a flat and shiny surface, corrosion resistance, bending resistance, and a plating layer that is not easily peeled off, and has high reliability when applied to elements such as semiconductors.

[0082] The above are merely preferred embodiments of the present invention, and the scope of protection of the present application is not limited to the above examples. Those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered to fall within the scope of protection of the present application.

Claims

1. 1. A process for electroplating palladium gold plated copper bonding wire, the process comprising: electroplating a first palladium layer onto a baseline copper surface using a first palladium plating solution, plating a second gold layer onto the plated blank using a first gold plating solution, plating a third palladium layer onto the plated blank using a second palladium plating solution, and finally plating a fourth gold layer onto the plated blank using a second gold plating solution; 1. A process for electroplating palladium-gold plated copper bonding wire, comprising the steps of: said first palladium plating solution comprising palladium tetraaminoacetate, 4-carboxybenzenesulfonamide and 6-azauracil.

2. The electroplating process for palladium gold plated copper bonding wire according to claim 1, characterized in that in the electroplating process, the concentration of the palladium tetraaminoacetate is maintained at 5-8 g / L, the concentration of the 4-carboxybenzenesulfonamide is maintained at 5-15 mg / L, and the concentration of the 6-azauracil is maintained at 1-5 mg / L in the first palladium plating solution.

3. 2. The electroplating process for palladium gold plated copper bonding wire according to claim 1, characterized in that the first palladium plating solution further contains methionine, and the concentration of the methionine in the first palladium plating solution is 10-20 mg / L.

4. 2. The electroplating process of claim 1, wherein the second palladium plating solution comprises palladium salt, 3-chloro-4-fluoroaniline, calcium dinonane naphthalene sulfonate, and β-cyanoalanine.

5. 5. The electroplating process for palladium gold plated copper bonding wire of claim 4, wherein the palladium salt is one or more of tetraaminopalladium dichloride, dinitrodiamminepalladium, diaminopalladium dichloride, and trans-diaminopalladium dibromide.

6. The electroplating process for palladium gold plated copper bonding wire according to claim 4, characterized in that in the electroplating process, the concentration of the palladium salt is maintained at 6-10 g / L, the concentration of the 3-chloro-4-fluoroaniline is maintained at 3-13 mg / L, the concentration of the calcium dinonane naphthalene sulfonate is maintained at 2-6 mg / L, and the concentration of the β-cyanoalanine is maintained at 12-22 mg / L in the second palladium plating solution.

7. 2. The electroplating process for palladium gold-plated copper bonding wire according to claim 1, wherein the first gold plating solution and the second gold plating solution are both potassium auric cyanide solutions, and the pH of the first gold plating solution and the second gold plating solution is adjusted with ammonia water during electroplating, and the pH of the first gold plating solution and the pH of the second gold plating solution are both 10 to 15.

8. 2. The electroplating process of claim 1, wherein the baseline copper diameter is 180-220 μm, the electroplating process further comprises a step of performing a first wiredraw on the plated blank to a post-drawn diameter of 90-105 μm, and the electroplating process further comprises a step of performing a second wiredraw on the plated finished product to a post-drawn diameter of 15-22 μm.

9. The electroplating process of palladium gold plated copper bonding wire according to claim 1, characterized in that, in the process of electroplating the first palladium layer, the second gold layer, the third palladium layer and the fourth gold layer, the electroplating temperature is set to 70-85°C, the current is set to 10-80mA, and the electroplating time of each layer is set to 10-30min.

10. 1. A palladium gold plated copper bonding wire, the palladium gold plated copper bonding wire being manufactured by the electroplating process of claim 1, the palladium gold plated copper bonding wire being, from the inside to the outside, a copper core wire, the first palladium layer, the second gold layer, the third palladium layer, and the fourth gold layer, in that order.

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