TW201818423A - Copper alloy wire and a method for manufacturing the same capable of improving the soldering capability of copper wire and preventing copper wire from oxidation - Google Patents

Abstract

Disclosed are a copper alloy wire and a method for manufacturing the same. The copper alloy wire is composed of 0.3 to 0.45 weight percentage of silver, 0.01 to 0.02 weight percentage of titanium, and the balance of copper and unavoidable impurities. The method for manufacturing the copper alloy wire comprises two stages of vacuum smelting First, a vacuum-arc smelting is employed to manufacture copper-titanium master alloy, and then a continuous casting method is performed on the copper-titanium master alloy and the remaining components through a vacuum induction melting to manufacture a copper alloy wire material. Then, a non-sliding extension line apparatus is employed to perform a wire drawing on the copper alloy wire material in a manner of uniform material flow to manufacture a copper alloy fine wire. Finally, argon gas is used as a protective gas to perform a thermal treatment on the copper alloy fine wire so as to complete the manufacturing process of the copper alloy wire.

Description

   Copper alloy wire and manufacturing method thereof   

The invention relates to a copper wire and a manufacturing method thereof, and more particularly to a copper alloy wire and a manufacturing method thereof.

In recent years, due to the rise in gold prices, the gold wires used as semiconductor packaging wires have begun to be replaced by other metal wires. The development of semiconductor package wires with material composition or innovative structures has become the main development direction in this field.

Therefore, copper metal, which has advantages in conductive properties and cost, has also been used as a main substitute material to develop wires. However, although copper metal has good conductivity and ductility and is inexpensive, but in practical applications, The easy oxidation of copper metal affects the conduction function and greatly reduces the life of the copper wire; therefore, the improvement of the oxidation of the copper wire through the improvement of the composition, process or structure has also become one of the research topics in the field.

For example, in the patent document (certificate number TW I509089), the cross-section structure of a pure copper alloy wire is disclosed. The composition of the wire is at least one base metal of 40 to 100 ppm titanium, zirconium, zinc, and tin, and the remaining portion is made of copper. The cross-sectional structure of the wire rod is a processed surface of the wire rod that has been reduced in diameter by diamond drawing eye mold processing. The surface of the wire rod forms an organic carbon layer composed of a total organic carbon content of 50 to 3000 μg / m ² .

The technology of the above-mentioned patent document (TW I509089) is mainly to prevent the copper oxide on the surface of the copper wire from deteriorating into spots, so that the base metal containing copper which is easily oxidized is first oxidized internally with oxygen atoms. Next, during the period when most of the surface oxide layer is still unsaturated copper oxide, an organic carbon layer that does not reduce the oxide layer is formed on the surface of the wire by a diamond stretching die, thereby achieving a redox balance of the copper oxide layer, and further Prevent the formation of spot-shaped copper oxide on the surface; however, when the copper wire of this patent is actually soldered to the aluminum pad, the solderability may be poor due to the composition ratio.

In addition, in the patent document (certificate number TW I512121), a bonding wire is disclosed, which includes: a core with a surface having copper as a main component, wherein the total amount of copper is at least 97%, and the other contains 0.5% to 3% palladium 45 to 900 ppm of silver; the technology of this patent document is that it incorporates a coating outside the core, the coating including at least one of Pd, Au, Pt, Ag as a main component. If the annealing temperature is selected as the variable parameter and the annealing time is set to a fixed value, it is particularly beneficial to select the annealing temperature as the annealing temperature value higher than the maximum elongation; in particular, the average grain size of the wire can be used by this manufacturing principle Adjusting the size to a larger grain size can positively affect other properties such as wire softness, ball bonding behavior, and so on.

However, in practical applications, the above-mentioned patent document (TW I512121), because its surface coating system includes at least one of Pd, Au, Pt, and Ag as the main component, it has a higher manufacturing cost and a higher sphericity than an unplated layer. It ’s bad.

In view of this, the present invention is to develop a copper alloy wire with a specific composition, which can not only improve its oxidation problem, but also maintain and improve its solderability.

The main problem to be solved by the present invention lies in the limitation of the application of the characteristics of easy oxidation of copper wires on semiconductor packages; therefore, the present invention adds silver and titanium as constituents and improves its manufacturing method to overcome the easy oxidation of copper wires. Problems, while improving the solderability of copper wires.

In order to achieve the above object, the present invention discloses a copper alloy wire, which is mainly composed of copper, silver, and titanium, and is made by vacuum melting in the following percentages by weight: 0.3 to 0.45 of silver and 0.01 to 0.02 of titanium And the rest is copper.

The copper alloy wire according to the present invention is made of copper alloy wire by continuous casting after two-stage melting in a vacuum state, and then drawn into a copper alloy fine wire through a wire drawing equipment, and finally annealed at a temperature of 580 ~ Heat treatment at 700 ° C (annealing time of 0.1 seconds or more) completes the process of copper alloy wires.

In the vacuum smelting step, the "two-stage smelting" is divided into the first stage of vacuum arc smelting and the second stage of vacuum induction smelting, as explained below: 1. Vacuum arc smelting: a full share of titanium and a portion of copper are vacuumed Arc melting to produce copper-titanium master alloy with lower melting point; 2. Vacuum induction melting: copper-titanium master alloy is inductively smelted into a molten copper alloy with all the silver and the remaining copper.

Next, the molten copper alloy after uniform melting will be continuously cast into copper alloy wire with a wire diameter of 8mm to 4mm, and then passed through a non-sliding wire drawing device at room temperature at 100 ~ 1000m / The copper alloy fine wire is drawn at a speed of 10 to 20 μm.

Finally, the copper alloy fine wire will use argon as a protective gas and complete the process of copper alloy wire by heat treatment at an annealing temperature of 580 ~ 700 ° C (annealing time of more than 0.1 second), so that the oxidation problem of the copper alloy wire is significantly improved, Achieve better weldability and optimize the overall mechanical properties.

A‧‧‧ full share of titanium

B1‧‧‧Part of copper

B2‧‧‧Remaining share of copper

C‧‧‧ full share of silver

100’‧‧‧Cu-Ti master alloy

100‧‧‧ molten copper alloy

300‧‧‧No-sliding wire drawing equipment

301‧‧‧tension control device

302‧‧‧eye mold

303‧‧‧copper alloy wire

S10 ~ S12‧‧‧ Vacuum melting step

S20‧‧‧Continuous casting steps

S30 ~ S31‧‧‧Drawing steps

S40 ~ S41‧‧‧‧Heat treatment steps

Figure 1A is a representation of the main components of the present invention and the first stage of smelting; Figure 1B is a representation of the main components of the present invention and the second stage of smelting; Figure 2A is a flowchart of the steps of the manufacturing method of the present invention; and Figure 2B is a vacuum of the present invention Figure 2C is a flow chart of the drawing step of the present invention; Figure 2D is a flow chart of the heat treatment step of the present invention; and Figure 3 is a schematic view of the non-sliding wire drawing device of the present invention.

First, please refer to FIG. 1A and FIG. 1B at the same time. FIG. 1A and FIG. 1B are the composition and melting method of the copper alloy wire according to the present invention. The present invention is that copper, silver, and titanium are vacuum smelted at the following weight percentages: Composition: 0.3 to 0.45 silver, 0.01 to 0.02 titanium, and the rest are copper.

Because the melting point of titanium is 1668 ° C, copper with a melting point above 1085 ° C and silver with a melting point of 961.8 ° C differ by nearly 600 ~ 700 ° C. In order to avoid the incomplete melting of titanium metal, it cannot be uniformly distributed in the molten copper alloy for casting, so The vacuum melting phase adopts "two-stage melting". As shown in Fig. 1A, "the full share of titanium A" and "part of the share of copper B1" are vacuum arc smelted to produce a "copper titanium master alloy 100 '" with a lower melting point; Then, as shown in FIG. 1B, the "copper-titanium master alloy 100 '", "the full share of silver C", and the "remaining share of copper B2" are all subjected to induction melting to "a molten copper alloy 100". For the above-mentioned portion of copper B1 and the remaining portion of copper B2, copper having a purity of 4N or more is used.

The copper alloy wire according to the present invention is made of a copper alloy wire by continuous casting through vacuum melting as shown in FIG. 2A, and then drawn into a copper alloy fine wire through a wire drawing device, and finally the heat treatment is performed to complete the copper alloy wire manufacturing process. The steps are as follows: Step S10: Two-stage melting under vacuum; Step S20: Copper alloy wire made by continuous casting; Step S30: Copper alloy fine wire drawn through wire drawing equipment; Step S40: 580 ~ 700 ° C The heat treatment is performed at an annealing time of 0.1 seconds or more.

It can be further understood in FIG. 2B that the “two-stage smelting” mentioned in step S10 is divided into step S11 of the first stage and step S12 of the second stage, which are described as follows:

Step S11: The titanium and master alloys with a lower melting point are produced by vacuum arc smelting of all the titanium and some copper. In detail, when titanium having a melting point of 1668 ° C is added to a copper metal liquid having a melting point of 1085 ° C, the copper metal liquid cannot completely melt the titanium metal therein. Therefore, in step S11, the titanium to be smelted and a part of the copper are first placed in The crucible is evacuated to reduce the pollution source in the air during the smelting process, and then the titanium and copper in the crucible are directly heated and melted through the electric arc to generate an arc. The copper and titanium are first refined to have a melting point closer to the melting point of copper. Copper-titanium master alloy. The purpose of this step is to prevent titanium with a higher melting point from being melted together with the remaining components into copper alloy wires under the condition of incomplete melting or uneven melting, resulting in uneven distribution of titanium metal inside the copper alloy. This results in a situation where the oxidation resistance of the copper alloy is not ideal.

Step S12: The copper-titanium master alloy is inductively smelted into a molten copper alloy with all the silver and the remaining copper.

In step S20 (as shown in FIG. 2A), the molten copper alloy melt is uniformly smelted into a copper alloy wire with a wire diameter of 8mm to 4mm through continuous casting. In the step of forming into a wire, based on the physical characteristics of the wire and the cost and convenience of casting, a continuous casting method is used to directly generate a continuous wire by pouring a copper alloy molten liquid into a continuously-vibrating and cooling runner mold.

Next, the copper alloy wire with a wire diameter of 8mm to 4mm is further drawn through the wire drawing equipment in step S30 through rough drawing, middle drawing, and fine drawing at room temperature at a speed of 100 ~ 1000m / min into 10 ~ 20μm. Fine copper alloy wire.

In one embodiment, the “copper-free wire drawing device” described in step S31 shown in FIG. 2C can be used to draw the copper alloy wire. For example, referring to FIG. 3, in the thread drawing step, the non-sliding wire drawing device 300 includes a force control device 301 and an eye mold 302, and the tension control device 301 (such as a tension rod) is used to increase behind the eye mold 302. The back pulling force of the copper alloy wire 303 can improve the uniformity of the material flow in the center of the wire to achieve better mechanical properties, and reduce the disconnection problems caused by fan-shaped defects common to grains in general drawing.

After the drawing is completed, the copper alloy fine wire will be subjected to a heat treatment at an annealing temperature of 580 to 700 ° C. and an annealing time of more than 0.1 seconds in step S40 to complete the process of the copper alloy wire; the copper alloy drawn through the non-sliding wire drawing equipment Fine wires, the grains on the surface can still maintain a relatively uniform size and distribution, so the uniformity of the internal flow of the wire after heat treatment is good, the mechanical properties of the wire can be optimized, and the wire has better ductility to facilitate After the welding operation of the package is verified by actual measurement, the breaking strength (BL) and elongation of the copper alloy wire of the present invention can be increased. In one embodiment, as shown in FIG. 2D, argon gas can be used instead of the common nitrogen gas as a protective gas during heat treatment to improve the problem of easy oxidation of the copper wire.

Please refer to Table 1, which are Examples 1 to 4 of different formulations of the present invention. The weight percentages of the components are as follows:     

Titanium metal is added to the composition in the present invention to improve the oxidation resistance of copper alloy wires, and the copper wires are easily oxidized during use, which leads to the loss of the characteristics of the wires. In the present invention, silver metal is added to the composition to improve the solderability of pure copper wires. Pure copper wires without silver metal have poor ball formation and copper balls are easy to fall off when soldered, and copper with silver metal is added. The alloy wire can form an intermetallic compound (IMC) layer with stronger welding strength during welding. It also has better performance in terms of breaking strength (BL) and elongation (EL) than pure copper wire.

Please refer to Table 2, which is a table of the differences in breaking strength (B.L.) and elongation (E.L.) of the pure copper wires of Examples 1 to 4 and 6N according to the present invention, as follows:     

To sum up, the present invention can achieve the following effects: 1. Add silver and titanium metal with trace components to improve the solderability and oxidation resistance of copper wires; 2. Vacuum continuous casting production equipment, combined with non-sliding wire drawing equipment The drawing process of the wire makes the wire of good quality and cleanliness; and 3. The heat treatment conditions of specific temperature and time are used to optimize the mechanical properties of the copper wire itself.

The foregoing implementation manners or embodiments of the technical means adopted by the present invention are not intended to limit the scope of patent implementation of the present invention. That is, all changes and modifications that are consistent with the meaning of the scope of the patent application of the present invention or made in accordance with the scope of the patent of the present invention are covered by the scope of the patent of the present invention.

Claims (10)

    A method for manufacturing a copper alloy wire includes: performing a vacuum melting step: smelting titanium, silver, and copper into a molten copper alloy; performing a continuous casting step: making the molten copper alloy into a copper alloy wire Performing a wire drawing step: drawing the copper alloy wire into a copper alloy fine wire; and performing a heat treatment step: completing the copper alloy wire with an annealing temperature of 580-700 ° C.         The method for manufacturing a copper alloy wire according to item 1 of the scope of the patent application, wherein the copper alloy wire includes: silver with a composition weight percentage of 0.3 to 0.45, titanium of 0.01 to 0.02, and the rest is copper and unavoidable Impurities.         The method for manufacturing a copper alloy wire according to item 1 of the scope of the patent application, wherein in the vacuum melting step, two-stage melting is performed in a vacuum manner, and firstly, a full portion of titanium and a portion of copper are smelted by arc melting. It is a copper-titanium master alloy, and the copper-titanium master alloy is made into the molten copper alloy by induction melting together with all the silver and the remaining copper.         The method for manufacturing a copper alloy wire according to item 1 of the scope of the patent application, wherein the wire diameter of the copper alloy wire is between 4 mm and 8 mm, and the wire diameter of the copper alloy fine wire is between 10 and 20 μm.         The method for manufacturing a copper alloy wire according to item 1 of the scope of the patent application, wherein the copper alloy wire is drawn into the copper alloy fine wire through a wire drawing device.         The method for manufacturing a copper alloy wire according to item 5 of the scope of patent application, wherein the wire drawing device is a non-sliding wire drawing device. In the wire drawing step, the non-sliding wire drawing device includes a force control device and One eye mold, the tension control device is used to increase the back tensile force of the copper alloy wire behind the eye mold.         The method for manufacturing a copper alloy wire according to item 6 of the scope of the patent application, wherein the non-sliding wire drawing device performs a drawing process on the copper alloy wire at a speed of 100 to 1000 m / min at room temperature.         The method for manufacturing a copper alloy wire according to item 1 of the scope of patent application, wherein argon gas is used as a protective gas during the heat treatment.         A copper alloy wire includes: silver with a composition weight percentage of 0.3 to 0.45, titanium of 0.01 to 0.02, the rest is copper with a purity of 4N or more, and unavoidable impurities.         A copper alloy wire is composed of only the following elements and their proportions: silver with a composition weight percentage of 0.3 to 0.45, titanium to 0.01 to 0.02, the remaining part is copper with a purity of 4N or more, and unavoidable impurities.