A method of producing a doped graphene copper bonding wire

Abstract

The application discloses a preparation method of copper bonding wire doped with graphene, which comprises the following steps: 1) according to the proportioning of each element of the copper bonding wire, the single elements are weighed, mixed, ground, screened, and then mixed with graphene oxide; 2) the mixed powder is melted to prepare copper alloy ingots with fixed sizes, the copper alloy ingots are subjected to rough drawing, medium drawing and fine drawing to obtain semi-finished wires; 3) the semi-finished wires are repeatedly heated and washed in the water solution of a reducing agent and then subjected to fine drawing; and 4) the fine wires are annealed, washed, and dried. In the application, the components of the copper bonding wire are mixed, refined and mixed with graphene oxide, the mixed powder is then melted to prepare copper alloy ingots, the copper alloy ingots are repeatedly immersed in the water solution of a reducing agent after multi-stage fine drawing, the surface graphene oxide is reduced into graphene, the self-lubricating property of the graphene increases the lubricity during drawing, the micro-cracks generated in the fine wires during cold drawing are reduced, and thus the copper bonding wire with stronger mechanical property is prepared.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of bonding wires, in particular to a preparation method of a copper bonding wire doped with graphene. BACKGROUND

[0002] As an important packaging material, the bonding wire has high precision requirements for various indexes. The final forming of the bonding wire is mostly casting forming, and the existing bonding wire is mostly a homogeneous structure of a single alloy. When stretched, the surface of the bonding wire may be cracked due to uneven stress.

[0003] There are two solutions to solve the micro-cracks generated in the forming process of the bonding wire. One is to reduce the number of cold drawing to reduce the probability of micro-cracks; and the other is to remedy after forming, such as plating or tempering. The Chinese patent CN 114086021 A discloses a rapid directional casting method of a bonding wire. The method adopts the process of reducing the number of multi-stage cold drawing to achieve the purpose of rapid forming. However, the method cannot use the traditional bonding wire forming equipment, the premise investment cost is high, and a new process needs to be explored. The Chinese patent CN 110164776 A discloses a manufacturing method of a protective plating layer of a bonding wire. The method realizes the densification of the original wire after cold drawing by adopting laser-induced deposition coating after the original wire is drawn from 450-550 mu m to 10-50 mu m. However, the above-mentioned methods for solving the micro-cracks of the bonding wire are all surface treatment of the bonding wire, and cannot solve the problem that the friction between the internal components of the bonding wire is too large to cause micro-cracks. SUMMARY

[0004] In view of the above problems, the application provides a preparation method of a copper bonding wire doped with graphene, which comprises the following steps: 1) the elements of the copper bonding wire are weighed according to the proportioning of each element, mixed, ground, and screened to obtain a mixed metal powder, and then the mixed metal powder is fully mixed with graphene oxide to obtain a molten mixed powder; 2) the molten mixed powder obtained in step 1) is melted to prepare a copper alloy ingot with a fixed size, and the copper alloy ingot is subjected to rough drawing, medium drawing and fine drawing to prepare a semi-finished wire with a diameter of 0.1-0.2 mm; 3) the semi-finished wire obtained in step 2) is heated and washed in a water solution of a reducing agent, dried, and then fine-drawn to 0.07-0.15 mm, and then heated and washed in a water solution of a reducing agent, dried, and then fine-drawn to 0.03-0.1 mm, and finally heated and washed in a water solution of a reducing agent, and dried; 4) the fine wire obtained in step 3) is annealed at 200-350 DEG C under nitrogen protection, washed with water and dried, and the copper bonding wire doped with graphene is obtained.

[0005] Specifically, in step 1), the fineness of the screen filtration is 400-1000 meshes, and the weight percentage of the graphene oxide in the melt mixed powder is 0.5%-2%; in step 3), the reducing agent is selected from one of sodium citrate, vitamin C or hydrazine hydrate, and the mass concentration of the aqueous solution is 3%-10%.

[0006] The present application first mixes and refines each component of the copper bonding wire with graphene oxide, then melts the mixed powder to prepare a copper alloy ingot, and then repeatedly immerses the copper alloy ingot in an aqueous solution of a reducing agent after multi-stage refinement and stretching, so as to reduce the graphene oxide on the surface into graphene. The self-lubricating property of the graphene increases the lubricity during stretching and reduces micro-cracks generated in the internal of the fine wire during cold drawing, thereby preparing a copper bonding wire with stronger mechanical properties. DETAILED DESCRIPTION

[0007] The present application is described below in combination with examples, and the examples are only used to explain the present application and are not used to limit the scope of the present application.

[0008] Example 1

[0009] A preparation method of a graphene-doped copper bonding wire, comprising the following steps:

[0010] 1) Each component element of the copper bonding wire is weighed according to the proportioning of each element: Cu 90%, Ag 3%, Au 1.5%, Pt 1%, Al 1.5%, Pd 1%, Ti 1%, Si 0.5% and B 0.5%, mixed and ground, 1000 mesh screen filtration is performed to obtain a mixed metal powder, and the mixed metal powder is fully mixed with graphene oxide to obtain a melt mixed powder, and the weight percentage of the graphene oxide in the melt mixed powder is 2%;

[0011] 2) The melt mixed powder obtained in step 1) is melted to prepare a copper alloy ingot with a fixed size, the copper alloy ingot is subjected to rough drawing, intermediate drawing and fine drawing to prepare a semi-finished wire with a diameter of 0.2 mm;

[0012] 3) The semi-finished wire obtained in step 2) is immersed in an aqueous solution of hydrazine hydrate with a mass concentration of 10% and heated to 60°C for water washing, dried and then fine drawn to 0.15 mm, then immersed in the same solution for water washing, dried and then fine drawn to 0.1 mm, and finally immersed in the same solution for water washing and dried;

[0013] 4) The fine wire obtained in step 3) is annealed by heating to 350°C under nitrogen protection, water washed and dried, and the present application is obtained.

[0014] Example 2

[0015] A preparation method of a graphene-doped copper bonding wire, comprising the following steps:

[0016] 1) Take each component element according to the proportion of each element of copper bonding wire: Cu 90%, Au 4%, Ag 4%, Ti 1% and Pt 1%, mix and grind, sieve to 800 mesh, get mixed metal powder, take graphene oxide, and mix with the mixed metal powder to prepare a melting mixed powder, and the weight of the graphene oxide in the melting mixed powder accounts for 1.5%;

[0017] 2) The melting mixed powder obtained in step 1) is melted to prepare a copper alloy ingot with a fixed size, and the gold alloy ingot is subjected to rough drawing, medium drawing and fine drawing to prepare a semi-finished wire with a diameter of 0.15mm;

[0018] 3) The semi-finished wire obtained in step 2) is washed with a 6% sodium citrate aqueous solution, heated to 40℃, dried, and then drawn to 0.1mm, then washed with the same solution, dried, and then drawn to 0.05mm, and finally washed with the same solution and dried;

[0019] 4) The fine wire obtained in step 3) is annealed under nitrogen protection at 275℃, washed with water and dried.

[0020] Example 3

[0021] A preparation method of a graphene-doped copper bonding wire, comprising the following steps:

[0022] 1) Take each component element according to the proportion of each element of copper bonding wire: Cu 91%, Ag 3.5%, Au 1%, Pt 1%, Al 1.5%, Pd 1% and Ti 1%, mix and grind, sieve to 400 mesh, get mixed metal powder, take graphene oxide, and mix with the mixed metal powder to prepare a melting mixed powder, and the weight of the graphene oxide in the melting mixed powder accounts for 0.5%;

[0023] 2) The melting mixed powder obtained in step 1) is melted to prepare a copper alloy ingot with a fixed size, and the gold alloy ingot is subjected to rough drawing, medium drawing and fine drawing to prepare a semi-finished wire with a diameter of 0.1mm;

[0024] 3) The semi-finished wire obtained in step 2) is washed with a 3% vitamin C aqueous solution, heated to 40℃, dried, and then drawn to 0.07mm, then washed with the same solution, dried, and then drawn to 0.03mm, and finally washed with the same solution and dried;

[0025] 4) The fine wire obtained in step 3) is annealed under nitrogen protection at 200℃, washed with water and dried.

[0026] The preparation methods of the copper bonding wires of Comparative Examples 1-3 are the same as those of the copper bonding wires of Examples 1-3 except that no graphene oxide is added to the copper bonding wires of Comparative Examples 1-3, and the copper bonding wires of Comparative Examples 1-3 are not washed with water after heating. The copper bonding wires of Examples 1-3 and Comparative Examples 1-3 are further stretched to a uniform diameter, and then tensile tests are performed. The test results are shown in Table 1.

[0027] Table 1. Test results of mechanical properties of the copper bonding wires of Examples 1-3 and Comparative Examples 1-3

[0028] Breaking force B.L (gf) / 20 μm Elongation EL (%) / 20 μm Example 1 16.75 10.36 Comparative Example 1 14.33 11.41 Example 2 15.86 10.22 Comparative Example 2 12.59 10.85 Example 3 16.30 10.71 Comparative Example 3 14.14 11.38

[0029] As can be seen from the data in Table 1, the copper bonding wires of Examples 1-3 containing graphene can significantly increase the mechanical properties and elongation properties compared to the copper bonding wires of Comparative Examples 1-3, which indicates that graphene plays a role in enhancing lubrication in the copper bonding wires and reduces micro-cracks in the copper bonding wires.

[0030] The above description is merely preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of making a doped graphene copper bonding wire, characterized by, Comprise the following steps: 1) The proportion of each element of copper bonding wire is weighed: Cu 91%, Ag 3.5%, Au 1%, Pt 1%, Al 1.5%, Pd 1% and Ti 1%, mixed and ground, 400 mesh sieve, mixed metal powder, take graphene oxide, and mixed metal powder is fully mixed, and the weight of the mixed powder is 0.5%; 2) The mixed powder obtained in step 1) is melted to prepare a copper alloy ingot with a fixed size, and the copper alloy ingot is subjected to rough drawing, medium drawing and fine drawing to prepare a semi-finished wire with a diameter of 0.1mm; 3) The semi-finished wire obtained in step 2) is put into a vitamin C aqueous solution with a mass concentration of 3%, heated to 40℃, washed with water, dried, and then drawn to 0.07mm, then put into the same solution, washed with water, dried, and finally put into the same solution, washed with water, and dried; 4) The fine wire obtained in step 3) is annealed under nitrogen protection at 200℃, washed with water and dried, and the product is obtained.