US20190161841A1

US20190161841A1 - Copper alloy wire and manufacturing method thereof

Info

Publication number: US20190161841A1
Application number: US16/262,167
Authority: US
Inventors: Tung-Chen Cheng; Chen-Hsueh CHIANG; Chia-Hao Hsu
Original assignee: Samson AG; Metal Industries Research and Development Centre
Current assignee: Samson AG; Metal Industries Research and Development Centre
Priority date: 2016-11-28
Filing date: 2019-01-30
Publication date: 2019-05-30
Also published as: US20180148816A1

Abstract

A copper alloy wire and a manufacturing method thereof are provided. The copper alloy wire includes: by weight percentage of components, 0.3 to 0.45 of silver (Ag), 0.01 to 0.02 of titanium, and a remaining part that is formed by copper and unavoidable impurities. The method for manufacturing the copper alloy wire is performing two-phase vacuum melting: first performing vacuum electric arc melting into a copper-titanium mother alloy, and then performing vacuum induction melting with remaining components into a copper alloy wire material by means of continuous casting; then drawing the copper alloy wire material into a copper alloy fine wire by a non-slip wire drawing device in a material even-flow wire drawing manner, and finally performing thermal treatment on the copper alloy fine wire by using argon as a protection gas, so as to complete a process of the copper alloy wire.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Division of application Ser. No. 15/361,620, filed on Nov. 28, 2016, the prior application is herewith incorporated by reference in its entirety.

BACKGROUND

Technical Field

The present disclosure relates to a method manufacturing a copper alloy, and in particular, to a copper alloy wire and a manufacturing method thereof.

Related Art

In recent years, because the price of gold rises, gold wires that are conventionally used as semiconductor encapsulation wires have begun to be replaced with other metal wires, and developing wires for semiconductor encapsulation wires by means of material components or innovative structures has become a main development direction of the field.
Therefore, copper metal, which has advantages in both conductivity and costs, is also used as a main alternative material to develop wires. However, although the copper metal has good conductivity and ductility as well as low price, in actual application, the attribute that the copper metal is easily oxidized affects the conduction function and greatly shortens life of copper wires. Therefore, improving the problem of copper wire oxidization by means of component, process or structural improvement has also become one of subjects to be researched in the field.
For example, in the patent document (Patent No. TW I509089), a profile construction of a pure copper alloy wire is disclosed; the wire is formed by at least one base metal of 40 to 100 ppm titanium, zirconium, zinc, or tin, and the remaining part is formed by copper; the profile construction of the wire is a machined surface, which is radially shrinked due to a process of a diamond wire drawing eye mold, and an organic carbon layer with a total organic carbon content of 50 to 3000 μg/m²is formed on a surface of the wire.
The technology of the foregoing patent document (TW I509089) mainly lies in making base metal elements easily oxidized and contained in a copper base metal first perform inner oxidization with oxygen atoms so as to inhibit copper oxides on a surface of a copper wire from deteriorating into spots. Next, in a period in which most copper oxides on the surface oxide layer are nonsaturated copper oxides, an organic layer that does not make the oxide layer reduced is formed on the surface of the wire by means of a diamond drawing die, so as to obtain redox equilibrium of the copper oxide layer, thereby preventing generation of spot-shaped copper oxides on the surface; however, when the copper wire of the patent document is actually welded with an aluminum pad, weldability may be poor owing to ratios of components.
Further, in the patent document (Patent No. TW I512121), a bonding wire is disclosed, wherein the bonding wire includes: a core that has a surface and uses copper as a main component, where a total share of content of copper is at least 97%, and 0.5% to 3% of palladium and 45 to 900 ppm silver (Ag) are further included; the technology of the patent document lies in that a coating is combined outside the core, and the coating includes at least one of Pd, Au, Pt, or Ag as the main component. If an annealing temperature is selected as a variable parameter, and annealing time is set as a constant value, then it is particularly beneficial to select the annealing temperature as an annealing temperature value greater than a maximum ductility; specifically, a size of an average grain of the wire may be adjusted to a size of a large grain by means of the manufacturing principle, and other properties, for example, wire softness, and ball bonding behaviors may be affected in a positive manner.
However, in actual application, because a surface coating of the bonding wire of the foregoing patent document (TW I512121) includes at least one of Pd, Au, Pt, or Ag as a main component, the bonding wire of the foregoing patent document (TW I512121) has high manufacturing costs and a ballability that is poorer than that of a bonding wire without a surface coating.
In view of the above, the present disclosure develops a copper alloy wire having specific components to not only improve an oxidization problem thereof, but also keep and improve weldability thereof.

SUMMARY

The main problem to be resolved by the present disclosure lies in limitation of the attribute that copper alloy wires are easily oxidized in application of semiconductor encapsulation. Therefore, the present disclosure adds silver (Ag) and titanium as components, and improves a manufacturing method thereof, so as to overcome the problem that copper alloy wires are easily oxidized as well as improve weldability thereof.
To achieve the foregoing objective, the present disclosure discloses a copper alloy wire, which is mainly formed by copper, silver (Ag), and titanium, and is melted in a vacuum manner in the following weight percentage: 0.3 to 0.45 of silver (Ag), 0.01 to 0.02 of titanium, and a remaining part of copper.
However, the copper alloy wire of the present disclosure is manufactured in the following way: after two-phase melting is performed in vacuum state, manufacturing a copper alloy wire material by means of continuous casting, and then performing drawing on the copper alloy wire material by a wire drawing device into a copper alloy fine wire, and finally performing thermal treatment at an annealing temperature of 580 to 700° C. (annealing time is greater than 0.1 second) to complete the copper alloy wire.
In the vacuum melting step, two-phase melting is divided into first-phase vacuum electric arc melting and second-phase vacuum induction melting, and description is stated as follows:
1. Vacuum electric arc melting: melting a total share of titanium and a partial share of copper into a copper-titanium mother alloy having a low melting point by means of vacuum electric arc melting; and
2. Vacuum induction melting: melting the copper-titanium mother alloy with a total share of silver (Ag) and a remaining share of copper together into a molten copper alloy by means of induction melting.
Next, the evenly molten copper alloy is casted into the copper alloy wire material with a wire diameter ranging between 8 mm and 4 mm by means of continuous casting, and then is drawn into the copper alloy fine wire with a wire diameter ranging between 10 μm and 20 μm by a non-slip wire drawing device at a speed of 100 to 1000 m/min at room temperature.
Finally, thermal treatment is performed on the copper alloy fine wire by using argon as a protection gas at an annealing temperature of 580° C. to 700° C. (annealing time is greater than 0.1 second), so as to complete the copper alloy wire, so that the oxidization problem of the copper alloy wire is obviously improved, and better weldability is achieved, and a function of overall mechanical property optimization is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the disclosure, and wherein:

FIG. 1A is a schematic diagram of main components and first-phase melting of the present disclosure;

FIG. 1B is a schematic diagram of main components and second-phase melting of the present disclosure;

FIG. 2A is a flowchart of steps of a manufacturing method of the present disclosure;

FIG. 2B is a flowchart of a vacuum melting step of the present disclosure;

FIG. 2C is a flowchart of a wire drawing step of the present disclosure;

FIG. 2D is a flowchart of a thermal treatment step of the present disclosure; and

FIG. 3 is a schematic diagram of a non-slip wire drawing device of the present disclosure.

DETAILED DESCRIPTION

First, referring to FIG. 1A and FIG. 1B at the same time, FIG. 1A and FIG. 1B are components and a melting manner of a copper alloy wire of the present disclosure, and the copper alloy wire of the present disclosure is manufactured in a vacuum melting manner using the following weight percentage of components: copper, silver (Ag), and titanium: 0.3 to 0.45 of silver (Ag), 0.01 to 0.02 of titanium, and a remaining part of copper.
Because a melting point of titanium metal is 1668° C., which is higher than a melting point of 1085° C. of copper and a melting point of 961.8° C. of silver (Ag) by almost 600 to 700° C., to prevent titanium metal from being unevenly distributed in the molten copper alloy for casting owing to incomplete melting. Two-phase melting is used in a vacuum melting phase: first, as shown in FIG. 1A, a total share of titanium A and a partial share of copper B1 are melted to a copper-titanium mother alloy 100′ having a low melting point by means of vacuum electric arc melting; and then as shown in FIG. 1B, the copper-titanium mother alloy 100′, a total share of silver (Ag) C and a remaining share of copper B2 are melted together to a molten copper alloy 100 by means of induction melting. The foregoing partial share of copper B1 and the remaining share of copper B2 both use copper with a purity greater than 4N.
However, the copper alloy wire of the present disclosure is manufactured in the following steps: manufacturing a copper alloy wire material by means of continuous casting in a vacuum melting manner shown in FIG. 2A, and then performing drawing on the copper alloy wire material by a wire drawing device into a copper alloy fine wire, and finally performing thermal treatment to complete a process of the copper alloy wire, and the steps are as follows:
step S10: perform two-phase melting in vacuum state (e.g., melting titanium, silver, and copper under a vacuum manner into a molten copper alloy);
step S20: manufacture the molten copper alloy into a copper alloy wire material by means of continuous casting;
step S30: perform drawing the copper alloy wire material to obtain a copper alloy fine wire by a wire drawing device; and
step S40: perform thermal treatment on the copper alloy fine wire under an annealing temperature (e.g., the annealing time is greater than 0.1 second, and the annealing temperature is ranged from 580 to 700° C.
According to FIG. 2B, it can be further known that “two-phase melting” mentioned in step S10 is divided into step S11 in a first phase and step S11 in a second phase, and description is stated as follows.
Step S11: melt a total share of titanium and a partial share of copper into a copper-titanium mother alloy having a low melting point by means of vacuum electric arc melting. In detail, when titanium having a melting point of 1668° C. is put into a copper metal liquid having a melting point of 1085° C., the copper metal liquid cannot make titanium metal completely melted therein, and therefore in step S11, titanium to be melted and partial copper are first placed in a crucible, which is vacuumized, so that a pollution source in air is reduced in a melting process. Then, titanium and copper in the crucible are directly heated and melted by electric arcs generated by a stun rod, so that copper and titanium are first melted into a copper-titanium mother alloy having a melting point closer to that of copper. An objective of this step lies in preventing titanium metal having a high melting point from being melted into a copper alloy wire with remaining components in state of incomplete melting or uneven melting, and consequently, distribution of titanium metal in the copper alloy is uneven, resulting in a case in which inoxidizability of the copper alloy is unsatisfactory.
Step S12: melt the copper-titanium mother alloy with a total share of silver (Ag) and a remaining share of copper together into a molten copper alloy by means of induction melting.
In step S20 (as shown in FIG. 2A), the molten copper alloy is casted from the even molten copper alloy into a copper alloy wire material with a wire diameter ranging between 8 mm and 4 mm by means of continuous casting; in this step of melting into a wire material, based on physical characteristics, casting costs and convenience of the wire material, a continuous casting process that directly pours the copper alloy molten liquid into a constantly vibrated and cooled casting die body to generate continuous wire materials is used.
Next, in step S30, coarse drawing, medium drawing, and fine drawing are performed on the copper alloy wire material with the wire diameter ranging between 8 mm and 4 mm by the wire drawing device at a speed of 100 to 1000 m/min at room temperature into a copper alloy fine wire with a wire diameter ranging between 10 μm and 20 μm.
In an embodiment, the “non-slip wire drawing device” in step S31 shown in FIG. 2C can be used to perform wire drawing on the copper alloy wire material. For example, referring to FIG. 3, in the wire drawing step, the non-slip wire drawing device 300 includes a tension control apparatus 301 and an eye mold 302, and the tension control apparatus 301 (for example, a tension rod) is configured to increase a back drawing force of the copper alloy wire 303 behind the eye mold 302, so that flowing uniformity of a wire central material is improved to a better mechanical property, and common broken wire problems derived from sector defects in general wire drawing are reduced.
In step S40: after wire drawing, thermal treatment at an annealing temperature of 580 to 700° C. for annealing time of greater than 0.1 second is performed on the copper alloy fine wire, so as to complete a process of the copper alloy wire. Grains on a surface of the copper alloy fine wire drawn by the non-slip wire drawing device can still maintain arrangement with both even sizes and even distribution, and therefore, flowing uniformity in the wire after thermal treatment is good, and mechanical properties of the wire may be optimized to make the wire have better ductility to facilitate encapsulation welding work. Upon measurement verification, a breaking level (B.L.) and an elongation level of the copper alloy wire of the present disclosure can be increased. In an embodiment, a problem that a copper alloy wire is easily oxidized can be improved by using argon in place of common nitrogen as a protection gas in thermal treatment in step S41 shown in FIG. 2D.
Referring to table I, table I lists examples 1 to 4 with different ratios of components of the present disclosure, and components by weight percentage are as follows:

TABLE I

Silver (Ag)	Titanium (Ti)	Copper (Cu)

Example 1	0.45	0.02	Remaining part
Example 2	0.45	0.01	Remaining part
Example 3	0.3	0.01	Remaining part
Example 4	0.3	0.02	Remaining part

The present disclosure adds titanium in components, so as to improve an antioxidant capacity of the copper alloy wire, thereby improving easy oxidization in use, which leads to lack of wire attributes, of the copper wire. The present disclosure adds silver (Ag) in components, so as to improve weldability of a pure copper wire. The conventional pure copper wire into which silver (Ag) is not added has cases in which ballability is poor and a copper ball easily detaches, but the claimed copper alloy wire into which silver (Ag) metal is added can form an intermetallic compound (IMC) layer having high welding strength in welding, and has performances better than the conventional pure copper wire in the breaking level (B.L.) and the elongation level (E.L.).
Referring to table II, table II is a table of differences between examples 1 to 4 of the present disclosure and a 6N pure copper wire in the breaking level (B.L.) and the elongation level (E.L.), and the differences are listed below:

TABLE II

Presentation data of a 6N pure copper wire in the
breaking level (B.L.) and the elongation level (E.L.)

	Breaking level (B.L.)	Elongation level (E.L.)

	4.34 g	9.87%
	4.23 g	8.69%
	4.14 g	9.08%
	4.24 g	9.21%

Presentation data of the present disclosure in the

breaking level (B.L.) and the elongation level (E.L.)

	Breaking level (B.L.)	Elongation level (E.L.)

Example 1	6.07 g	11.76%
Example 2	5.60 g	12.18%
Example 3	5.82 g	12.02%
Example 4	5.83 g	12.01%

Based on the above, the present disclosure can achieve the following effects:
1. Adding silver (Ag) and titanium in trace elements, so as to improve weldability and an antioxidant capacity of a copper wire;
2. Performing vacuum continuous casting on a manufacturing device, and making a wire have good quality and high cleanness in combination with a wire drawing process of a non-slip wire drawing device; and
3. Optimizing mechanical properties of the copper wire itself under thermal treatment conditions at a specific temperature for specific time.
The foregoing implementation manners or examples of the technical means used in the present disclosure are not intended to limit the implementation scope of the present patent for invention. Equal variations and modifications that accord with literary content of the patent application scope of the present disclosure or that are made according to the scope of the present disclosure patent are covered by the scope of the present disclosure patent.

Claims

What is claimed is:

1. A method for manufacturing a copper alloy wire, comprising:

performing a vacuum melting step: melting titanium, silver, and copper into a molten copper alloy;

performing a continuous casting step: manufacturing the molten copper alloy into a copper alloy wire material;

performing a wire drawing step: drawing the copper alloy wire material into a copper alloy fine wire; and

performing a thermal treatment step: performing thermal treatment on the copper alloy fine wire under a condition that an annealing temperature is ranged from 580° C. to 700° C.

2. The method for manufacturing a copper alloy wire according to claim 1, wherein the copper alloy wire comprises: by weight percentage of the copper alloy wire, 0.3 to 0.45 of silver, 0.01 to 0.02 of titanium, and a remaining part that is formed by copper and unavoidable impurities.

3. The method for manufacturing a copper alloy wire according to claim 1, wherein in the vacuum melting step, two-phase melting is performed in a vacuum manner and comprises steps of: first melting a total share of titanium and a partial share of copper into a copper-titanium mother alloy by means of electric arc melting, and then melting the copper-titanium mother alloy with a total share of silver and a remaining share of copper together into the molten copper alloy by means of induction melting.

4. The method for manufacturing a copper alloy wire according to claim 3, wherein the partial share of copper uses copper with a purity greater than 4N.

5. The method for manufacturing a copper alloy wire according to claim 3, wherein the remaining share of copper uses copper with a purity greater than 4N.

6. The method for manufacturing a copper alloy wire according to claim 1, wherein a wire diameter of the copper alloy wire material ranges between 4 mm and 8 mm.

7. The method for manufacturing a copper alloy wire according to claim 1, wherein a wire diameter of the copper alloy fine wire ranges between 10 μm and 20 μm.

8. The method for manufacturing a copper alloy wire according to claim 1, wherein the copper alloy wire material is drawn into the copper alloy fine wire by a wire drawing device.

9. The method for manufacturing a copper alloy wire according to claim 8, wherein the wire drawing device comprises a non-slip wire drawing device.

10. The method for manufacturing a copper alloy wire according to claim 9, wherein in the wire drawing step, the non-slip wire drawing device comprises a tension control apparatus and an eye mold, and the tension control apparatus is configured to increase a back drawing force of the copper alloy wire material behind the eye mold.

11. The method for manufacturing a copper alloy wire according to claim 9, wherein the non-slip wire drawing device performs a wire drawing process on the copper alloy wire material at a speed of 100 to 1000 m/min at room temperature.

12. The method for manufacturing a copper alloy wire according to claim 8, wherein coarse drawing, medium drawing and fine drawing of the wire drawing device are performed on the copper alloy wire material into the copper alloy fine wire.

13. The method for manufacturing a copper alloy wire according to claim 1, wherein the thermal treatment for annealing time of greater than 0.1 second is performed on the copper alloy fine wire.

14. The method for manufacturing a copper alloy wire according to claim 1, wherein a protection gas is used in the thermal treatment process.

15. The method for manufacturing a copper alloy wire according to claim 14, wherein argon is used as the protection gas in the thermal treatment process.

16. The method for manufacturing a copper alloy wire according to claim 1, wherein the copper alloy wire, only consisting of the following elements:

by weight percentage of components, 0.3 to 0.45 of silver, 0.01 to 0.02 of titanium, and a remaining part that is formed by copper and unavoidable impurities.

17. A method for manufacturing a copper alloy wire, comprising:

melting titanium, silver, and copper under a vacuum manner into a molten copper alloy;

manufacturing the molten copper alloy into a copper alloy wire material;

drawing the copper alloy wire material into a copper alloy fine wire; and

performing a thermal treatment on the copper alloy fine wire under an annealing temperature.

18. The method for manufacturing a copper alloy wire according to claim 17, wherein the annealing temperature is ranged from 580° C. to 700° C.

19. The method for manufacturing a copper alloy wire according to claim 17, wherein the step of melting titanium, silver, and copper comprises steps of: first melting a total share of titanium and a partial share of copper into a copper-titanium mother alloy by means of electric arc melting, and then melting the copper-titanium mother alloy with a total share of silver and a remaining share of copper together into the molten copper alloy by means of induction melting.

20. The method for manufacturing a copper alloy wire according to claim 17, wherein the copper alloy wire material is drawn into the copper alloy fine wire by a wire drawing device.