CN103056191A - Novel preparation method for noble composite metallic bond composite wire materials - Google Patents

Abstract

The invention discloses a preparation method for expensive/expensive composite wire and expensive/cheap composite wire which is simple in operation, controllable in thickness of the composite layer, clean in interface, well bonded in interface, and easy for subsequent processing. The preparation process is that the outer layer metal is ingot-cast, extruded and drawn into a round tube, and the wall thickness is in accordance with the product design requirements. Then put the precious metal round tube in the water-cooled mold, put the core metal in the vacuum induction melting furnace to melt the core metal, pour the core metal liquid into the water-cooled mold, and quickly solidify, adjust the water-cooled mold, and change the core material The cooling rate of the molten metal can be controlled to obtain a composite rod of the bonding layer (transition layer) between the cladding material and the core material. After the composite bar is processed by swaging, intermediate heat treatment, and wire drawing, the product size required by the customer is obtained. The composite wire prepared by this method has uniform metal coating on the outer layer, good synergistic deformation with the core material, and tight combination of the coating material and the core material, and can be used in advanced packaging such as integrated circuits, partially or completely replacing precious metal bonding. silk.

Description

A new method for preparing precious metal composite bonding wire

technical field

The invention belongs to the technical field of composite materials, and in particular provides a method for a precious metal composite bonding wire for semiconductor packaging. It can be used in the preparation of expensive/noble composite bonding wires and noble/basic composite bonding wires, and can also be popularized and applied to the preparation of other composite metal wires. the

Background technique

With the development of integrated circuit and semiconductor device packaging technology towards multi-lead, high integration and miniaturization, packaging materials require the use of bonding wires with thinner wire diameters and better electrochemical performance for narrow-pitch and long-distance bonding. . At the same time, in order to reduce production costs, it is hoped that base metals can be used instead of precious metals. the

So far, the methods for combining two or more materials into one body and suitable for large-scale production mainly include mechanical methods, plastic deformation methods, and metallurgical methods. The mechanical method is divided into methods such as inserting, hydraulic expansion, and drawing, which are characterized by mechanical bonding at the interface of each composite layer and low interface bonding strength. Although the plastic deformation method can achieve metallurgical bonding, it is very difficult to obtain a composite interface without scale, inclusions, and complete cleanliness. Metallurgical methods include reverse solidification method, cladding layer continuous casting method, core filling continuous casting method, and multi-layer composite material one-time casting forming method. This kind of method is beneficial to solidification feeding and rolling processing. Generally, the outer metal liquid is attached to the core material to solidify or the core metal liquid is solidified in the outer metal tube, but there are certain limitations. For example, only thick The cladding composite material of the wall, the core filling continuous casting is only suitable for the composite material with the melting point of the outer metal higher than the melting point of the core material. the

Contents of the invention

The purpose of the present invention is to develop a kind of expensive/expensive composite wire material, expensive/expensive composite wire, which is simple to operate, highly versatile, controllable in thickness of cladding layer, controllable in thickness of interface metallurgical bonding layer, clean in interface, good in interface bonding, and easy for subsequent processing. Preparation method of base composite wire. the

Process of the present invention is:

(1) The high-purity outer layer metal is cast, extruded, and drawn into a round tube. The outer diameter of the round tube is the same as the inner diameter of the water-cooled mold, and the wall thickness of the round tube is in accordance with the product design requirements;

(2) Clean the inner wall of the precious metal circular tube;

(3) The precious metal circular tube is placed in the water-cooled mold;

(4) Put the water-cooled mold in the vacuum furnace, and pass the cooling water, place the core material in the vacuum induction melting furnace, and adjust the casting position;

(5) Pre-evacuation and repeated cleaning with argon filling, high vacuum up to below 1×10 ^-2 Pa, then filling with argon up to 0.05Mpa, heating and melting;

(6) Casting: Pour the molten metal of the core material into the water-cooled mold for rapid solidification to obtain a composite bar;

(7) Forging processing;

(8) Intermediate heat treatment;

(9) Drawing: the round bar is drawn into a wire through a wire drawing machine;

(10) annealing;

(11) Testing and analysis of mechanical properties. the

(12) Winding: The wire is divided into small shafts of different lengths. the

The high-purity outer metal is Au, Ag, Pt or Pd, and the core metal is Ag, Cu or Al. the

The purity of the high-purity outer metal is ≥99.999%, and the purity of the core metal is ≥99.95%. the

The length of the precious metal circular tube is equal to the depth of the water-cooled mold, and the inner wall of the circular tube is wiped with acetone or gasoline. the

The water inlet pipe and the water outlet pipe of the water-cooled mold each have a control valve for adjusting the water inlet and outlet. The water flow is 1-20L/min, the water pressure is 0.1-2MPa, and the water temperature is ≤ 20°C. the

The forging press is a rotary forging process, and the deformation amount of each pass is controlled at 10%-20%. the

By adjusting the inner diameter of the water-cooling mold, the water volume of the water-cooling mold, and the thickness of the precious metal tube wall, the cooling rate of the core metal liquid is changed, so that the thickness of the bonding layer (transition layer) between the cladding material and the core material can be controlled, and the thickness of the cladding layer is uniform. , The interface is well bonded, composite rods. After the composite bar is processed by swaging, intermediate heat treatment, wire drawing, and heat treatment, the product size required by the customer is obtained. the

Advantages of the present invention:

(1) By adjusting the inner diameter of the water-cooling mold, the water volume of the water-cooling mold, and the thickness of the precious metal tube wall, the cooling rate of the core metal liquid is changed, so that the thickness of the bonding layer (transition layer) between the cladding material and the core material can be controlled, which is beneficial Subsequent processing. the

(2) There is no requirement for the melting point of cladding material and core material. A high melting point material can be prepared to coat a low melting point material, and a low melting point material can be coated with a high melting point material. the

(3) There is no requirement for the thickness of the precious metal pipe wall, and composite materials with different coating thicknesses can be prepared according to the needs. the

(4) The interface is clean. Since the core material is solidified from bottom to top, the interface impurities can float up smoothly. the

(5) In the rough machining stage, rotary forging is used to ensure the uniform deformation of the cladding layer and the core material, and the thickness of the cladding layer is uniform. the

Detailed ways

The present invention will be described in detail below in conjunction with the embodiments. the

Embodiment 1:

Preparation of Ag/Cu Composite Wire

Preparation:

(1) Ag with a purity greater than 99.999% is selected to form a round tube through ingot casting, extrusion, and drawing. The outer diameter of the round tube is 20 mm, the wall thickness is 2 mm, and the length is 100 mm. the

(2) Wipe and clean the inner wall of the Ag tube with acetone. the

(3) The Ag tube is placed in a water-cooled mold with an inner diameter of 20mm. the

(4) Put the water-cooled mold in the vacuum furnace, and pass the cooling water, the water intake is 10L/min, the water pressure is 0.5MPa, and the water temperature is ≤20°C. Cu with a purity ≥ 99.95% is placed in a vacuum induction melting furnace, and the casting position is adjusted. the

(5) Pre-evacuate and fill with argon for repeated cleaning twice, evacuate to a high vacuum to 6×10 ^-3 Pa, then fill with argon to 0.05Mpa, heat up and melt.

(6) Casting: The molten metal of the core material is poured into a water-cooled mold for rapid solidification to obtain an Ag-coated Cu composite rod. the

(7) Swivel processing: From Φ20mm-Φ6mm, the deformation of each pass is controlled at 10%-15%. the

(8) Intermediate heat treatment: Vacuum annealing of Φ6mm composite rods, 600°C, 1h. the

(9) Drawing: the Ag/Cu composite rod is drawn into wires of different diameters through a wire drawing machine. the

(10) Annealing: According to different requirements of customers, set different annealing parameters, eliminate stress, and obtain mechanical properties that meet the requirements

(11) Mechanical performance testing and analysis: check whether the product meets the requirements. the

(12) Winding: Wind the Ag-clad Cu composite wire into small shafts of different lengths according to different requirements of customers. the

(13) Final inspection: surface, wire diameter, wire setting, stress, mechanical properties, length, coating and other inspections. the

(14) Packaging

Example two

Preparation of Au/Ag Composite Wires

Preparation:

(1) Au with a purity greater than 99.999% is selected to form a round tube through ingot casting, extrusion, and drawing. The outer diameter of the round tube is 18 mm, the wall thickness is 1.5 mm, and the length is 100 mm. the

(2) Wipe and clean the inner wall of the Au tube with acetone. the

(3) The Au tube is placed in a water-cooled mold with an inner diameter of 18mm. the

(4) Put the water-cooled mold in the vacuum furnace, and pass cooling water, the water intake is 15L/min, the water pressure is 0.5MPa, and the water temperature is ≤20°C. Ag with a purity of ≥99.99% is placed in a vacuum induction melting furnace, and the casting position is adjusted. the

(5) Pre-evacuate and fill with argon for repeated cleaning twice, evacuate to a high vacuum to 6×10 ^-3 Pa, then fill with argon to 0.05Mpa, heat up and melt.

(6) Casting: pour the molten metal of the core material into a water-cooled mold for rapid solidification to obtain an Au-coated Ag composite rod. the

(7) Rotary forging: From Φ18mm-Φ5mm, the deformation of each pass is controlled at 15%-20%. the

(8) Intermediate heat treatment: Vacuum annealing of Φ5mm composite rods, 600°C, 1h. the

(9) Drawing: Au/Ag composite rods are drawn into wires of different diameters through a wire drawing machine. the

(10) Annealing: According to different requirements of customers, set different annealing parameters, eliminate stress, and obtain mechanical properties that meet the requirements

(11) Mechanical performance testing and analysis: check whether the product meets the requirements. the

(12) Winding: Wind the Au-clad Ag composite wire into small shafts of different lengths according to different requirements of customers. the

(13) Final inspection: surface, wire diameter, wire setting, stress, mechanical properties, length, coating and other inspections. the

(14) Packaging

Embodiment three

Preparation of Pd/Cu composite wire

Preparation:

(1) Select Pd with a purity greater than 99.999% to form a round tube through ingot casting, extrusion, and drawing. The outer diameter of the round tube is 15 mm, the wall thickness is 1.5 mm, and the length is 100 mm. the

(2) Wipe and clean the inner wall of the Pd tube with gasoline. the

(3) The Pd tube is placed in a water-cooled mold with an inner diameter of 15mm. the

(4) Put the water-cooled mold in the vacuum furnace, and pass the cooling water, the water intake is 8L/min, the water pressure is 0.4MPa, and the water temperature is ≤20°C. Cu with a purity ≥ 99.99% is placed in a vacuum induction melting furnace, and the casting position is adjusted. the

(5) Pre-evacuate and fill with argon for repeated cleaning twice, evacuate to a high vacuum to 6×10 ^-3 Pa, then fill with argon to 0.05Mpa, heat up and melt.

(6) Casting: Pour the molten metal of the core material into a water-cooled mold for rapid solidification to obtain a Pd-coated Cu composite rod. the

(7) Swivel processing: from Φ15mm-Φ7mm, the deformation of each pass is controlled at about 10%. the

(8) Intermediate heat treatment: Vacuum annealing of Φ7mm composite rods, 750°C, 1.5h. the

(9) Drawing: The Pd/Cu composite rod is drawn into wires of different diameters through a wire drawing machine. the

(10) Annealing: According to different requirements of customers, set different annealing parameters, eliminate stress, and obtain mechanical properties that meet the requirements

(11) Mechanical performance testing and analysis: check whether the product meets the requirements. the

(12) Winding: According to different requirements of customers, Pd-clad Cu composite wires are wound into small shafts of different lengths. the

(13) Final inspection: surface, wire diameter, wire setting, stress, mechanical properties, length, coating and other inspections. the

(14) Packaging.

Claims (7)

1. A preparation method for producing precious metal composite bonding wire, is characterized in that comprising the following steps: (1) The high-purity outer metal is cast, extruded, and drawn into a round tube. The outer diameter of the round tube is the same as the inner diameter of the water-cooled mold, and the wall thickness of the round tube is in accordance with the product design requirements; (2) Clean the inner wall of the precious metal circular tube; (3) The precious metal circular tube is placed in the water-cooled mold; (4) Put the water-cooled mold in the vacuum furnace, and pass the cooling water, place the core material in the vacuum induction melting furnace, and adjust the casting position; (5) Pre-evacuation and repeated cleaning with argon filling, high vacuum up to below 1×10 ^-2 Pa, then filling with argon up to 0.05Mpa, heating and melting; (6) Casting: Pour the molten metal of the core material into the water-cooled mold for rapid solidification to obtain composite rods; (7) Forging processing; (8) Intermediate heat treatment; (9) Drawing: the round bar is drawn into a wire through a wire drawing machine; (10) Annealing; (11) Testing and analysis of mechanical properties. (12) Winding: the wire is divided into small shafts of different lengths. 2. The preparation method for producing noble metal composite bonding wire as claimed in claim 1, wherein the high-purity outer layer metal is Au, Ag, Pt or Pd, and the core metal is Ag, Cu or Al. 3. The preparation method for producing noble metal composite bonding wire as claimed in claim 1, characterized in that the purity of the high-purity outer metal is ≥99.999%, and the purity of the core metal is ≥99.95%. 4. The preparation method for producing noble metal composite bonding wire as claimed in claim 1, wherein the length of the noble metal circular tube is equal to the depth of the water-cooled mold, and the inner wall of the circular tube is wiped with acetone or gasoline. 5. the preparation method of producing precious metal composite bonding wire as claimed in claim 1, is characterized in that the water inlet pipe and the water outlet pipe of the water-cooled mold each have a control valve, which is used to adjust the water inlet and water outlet, and the water flow is between 1-20L/min, water pressure 0.1-2MPa, water temperature ≤20℃. 6. the preparation method of producing precious metal composite bonding wire as claimed in claim 1, is characterized in that by adjusting the inner diameter of the water-cooling mold, the water volume of the water-cooling mold, the thickness of the precious metal tube wall, changing the cooling rate of the core material molten metal, can realize The thickness of the bonding layer between the coating material and the core material, that is, the transition layer, is controllable, which improves the subsequent processing performance of the material. 7. The preparation method for producing noble metal composite bonding wire as claimed in claim 1, characterized in that said forging is swaging, and the amount of deformation per pass is controlled at 10%-20%.